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Possible hydraulics futures for South Africa towards 2055

  • Authors: Naidoo, Franck
  • Date: 2020
  • Subjects: Climate changes -- South Africa , Shale gas industry -- Case Studies
  • Language: English
  • Type: Thesis , Doctoral , DBA
  • Identifier: http://hdl.handle.net/10948/50620 , vital:42279
  • Description: This research makes a contribution to the body of knowledge on unconventional oil and gas extraction (UOG) in the Karoo, South Africa. It provides a detailed analysis grounded in future studies theory and practice, which supports the argument that UOG extraction in the Karoo may potentially be conducted under the careful guidance of sustainable development and climate change principles. It is informed by the researcher’s perceptive and experience as a manufacturer of oil and gas products and his understanding of the fossil fuel sector and the role it currently plays in the South African economy. It is further informed by the researcher s understanding of the sector’s damaging climatic and environmental impacts. The practice of offering new insights through the application of futures studies is central to the process, and specific methodologies and tools have been used to develop four scenarios for the UOG extraction in South Africa. This framework allows for easy assessment for policy-making. Never has scenario art, which has been expertly created during the workshops, been used in South Africa to generate memorable and lasting scenarios memorable and lasting scenarios. This research seeks to provide insight regarding for South Africa’s quest for energy security in ways that support the climate change agenda. Given the shale controversies, most environmentalists prefer lower-carbon and reduced fossil fuel usage. However, South Africa can ill-afford this luxury at this stage and while the research considers the option of no-shale exploration and a direct path to renewable energy solutions (the ‘No-Shale, what now?’ scenario) it also. proposes other options for consideration. An integrated vision is put forth as the preferred scenario in which shale is the conduit to a sustainable energy future and which implements wide-scale climate change mitigation and adaptation strategies.
  • Full Text:
  • Date Issued: 2020

Post release evaluation of the distribution and efficacy of Eccritotarsus catarinensis and Eccritotarsus eichhorniae on Pontederia crassipes in South Africa

  • Authors: Maseko, Zolile
  • Date: 2020
  • Subjects: Water hyacinth -- Biological control -- South Africa , Weeds -- Biological control -- South Africa , Miridae -- South Africa , Insects as biological pest control agents -- South Africa
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/143046 , vital:38196
  • Description: Biological control involves the release of new species into the environment and therefore, needs to be carefully monitored through post-release assessments which have been largely neglected in the science. Post-release evaluations of biological control programmes reveal whether the control agent has established and if it impacts weed demography, while cost-benefit analyses require a different set of data that show the magnitude on return on investment. The biological control effort on Pontederia crassipes in South Africa uses, amongst others, two species of mirid, Eccritotarsus catarinensis and E. eichhorniae. Initially, they were released as a single species, but were recently divided using molecular techniques. Eccritotarsus catarinensis was released in 1999, and E. eichhorniae in 2007. After many releases over two decades, there was need to assess where each species was established in the country. Molecular techniques proved to be valuable in identifying the two species as they are morphologically indistinguishable in the field. Therefore, molecular techniques should be routinely used for screening biocontrol agents, whether new or as re-introductions. Annual surveys of the mirid release sites around South Africa were undertaken between 2016 and 2019. At each site both insect and plant parameters were measured. Only E. catarinensis is established in the field in South Africa despite the multiple releases of E. eichhorniae at over 70 sites across the country, and E. catarinensis has established at only 22 of the 45 release sites accessed during this study. This thesis tested climate, interaction with other agents already on P. crassipes, and direct competition between the two mirid species as reasons for the lack of establishment of E. eichhorniae. The results of the country-wide surveys showed that climate and water trophic status were the major determinants in the establishment of E. catarinensis. Most of the establishment was recorded in the warmer regions of the country, however, a few populations of the mirid also established in cooler areas, thus demonstrating a degree of thermal plasticity, and possible microclimates as the mirids persisted at sites shaded by riparian vegetation. Stochastic events such as active herbicide campaigns, winter frosts, droughts and floods were responsible for the absence of the mirid at some sites. At some of the eutrophic sites, despite the abundance of E. catarinensis, plants still proliferated as the water trophic status facilitated plant growth, thus, plants were able to compensate for the damage inflicted by the mirid. A more intensive, monthly, post-release evaluation was conducted on the Kubusi River, Eastern Cape Province between 2016 and 2019. This is regarded as one of the cooler water hyacinth sites. Populations of biological control agents at this site fluctuated seasonally. At this site, cold winters caused frosting of the leaves of P. crassipes with the exception of plants growing under overhanging vegetation that provided a refuge for the mirid. But, cool temperatures in the winter months (May to August) severely reduced the populations of E. catarinensis that required a long recovery phase in spring. The consequence of this was that the plants grew unchecked from the onset of the growing season forming dense mats. Of the four agents at the Kubusi River site, Eccritotarsus catarinensis recovered slowest after winter, with lag phases ranging from two months to several months of the three-year period. The release of a suite of agents has implications on the agents themselves, where interactions between the agents can be important. Interactions between pairs and even multiple agents can have implications for biocontrol, where agents are either complimentary or interfere with each other. In this case, because E. catarinensis recovered the slowest of the four agents at the site, plants were of a poor quality by mid-summer resulting in low mirid populations. Competition in weed biological control could be expected to be strongest between pairs of agents that share the same niche, and this could be the reason why E. eichhorniae failed to establish at sites where E. catarinensis had already been established for several years. When the two mirids were combined in manipulated trials in a polytunnel, populations were lower compared to when the two mirids occurred separately. Under warm conditions, it is likely that E. eichhorniae would be the superior agent compared to E. catarinensis. The evaluations discussed in this thesis highlighted gaps in agent release methodology in multispecies settings, as well as the need for strategic augmentation pre- and post-winter. It is important to release agents that will complement each other rather than compete, therefore, when releasing agents in a multispecies setting, niche differentiation needs to be considered. Here it is concluded that the best practice for dealing with the mirids is that they should be released individually, and at sites that have no other biological control agents in order to ultimately assess their efficacy. Landscape level, long-term monitoring of biological control programmes shows the impact of the control programme at a broader scale and, are far more informative than short-term studies and at fewer sites. Long-term post-release evaluations should be mandatory in biological control programmes. Furthermore, these assessments will help develop new strategies or improve on existing ones, thus achieve greater success in control.
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  • Date Issued: 2020

Post-apartheid nostalgia and the future of the black visual archive

  • Authors: Nsele, Zamansele Nsikakazi Busisiwe
  • Date: 2020
  • Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/167177 , vital:41444
  • Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
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  • Date Issued: 2020

Practices, dynamics and discourses of cross-racial adoption: the case of Buffalo city municipality in South Africa

  • Authors: Nyasha, Kausi
  • Date: 2020
  • Subjects: Interracial adoption -- South Africa -- Eastern Cape Adoption -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Doctoral , PhD(Social Work)
  • Identifier: http://hdl.handle.net/10353/18009 , vital:42003
  • Description: This study investigated the practices, dynamics, and discourses pertaining to crossracial adoption (CRA) in the Buffalo City Municipality (BCM) in South Africa. The researcher made use of qualitative methods to collect and analyse relevant data, which was made from both the in-depth interviews and focus group discussions. The research sample comprised of six adoption social workers, ten adoptive parents and ten adoptees, who were selected by means of purposive non-random sampling. The researcher also made use of observations, in order to that relevant, valuable, and rich information could be obtained. All the data was subsequently analysed by means of thematic analysis. The principal findings of the study revealed that although it has been legal since 1991, the practices of CRA in South Africa continues to be controversial and that, in the vast majority of cases, it entails black children being adopted by white parents. Relevant discourses covered cultural genocide, the best interests of adopted children, racial identity, colour-blindness, acculturation, and racial consciousness. The phenomenon of CRA needed to be evaluated from all of these standpoints, owing to the racial, cultural, and political perceptions which continue to linger after generations of enforced racial segregation in South Africa. It is evident from the findings that perceptions pertaining to race, culture, and politics exert a significant influence on social relations in the caring for and protection of vulnerable children and on family dynamics in adoptive families. It also emerged from the findings that CRA placements have begun to decline significantly, owing to factors such as long and tedious assessment processes, the xviii attitudes of social workers, a general lack of adequate pre- and post-adoption support for adoptive parents, and shortages of adoption social work staff and resources. The researcher endeavoured to assess the roles of adoption social workers within the adoption triad with respect to determining the adoptability of children and matching them with prospective adoptive parents, recruiting and selecting prospective adoptive parents, counselling prospective parents, counselling biological parents, counselling adopted children, and the providing of post-adoption services. It could be concluded from the findings that although the practice of CRA is an efficacious and desirable form of care for children who are in need of protection, despite any present shortcomings in relation to legislation pertaining to the practice, the phenomenon requires considerably more attention from relevant academics and researchers than it has received to date. The overarching conclusion which emerged from the findings was that although the practice of CRA has attracted controversy and denunciations from several racial groups, it has unlimited potential for erasing the racial stigmas which continue to haunt South African society as well as affording permanency care to those children who are in need of it. The study ends with some recommendations as well as a conceptual framework to deal with the issues of the practices, dynamics and discourses of CRA in South Africa.
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  • Date Issued: 2020

Pre-Service Teachers’ Perceptions about the Value of Teaching Practice Assessment as a Catalyst to the Improvement of Quality Model

  • Authors: Bako, Yellow
  • Date: 2020
  • Subjects: Teaching -- Evaluation Effective teaching
  • Language: English
  • Type: Thesis , Doctoral , PhD (Education)
  • Identifier: http://hdl.handle.net/10353/17921 , vital:41978
  • Description: Teaching Practice assessment is criticized for not promoting critical reflection and problem-solving thinking in pre-service teachers as expected. Pre-service teachers lack praxis: translating theoretical knowledge into authentic practice. Teaching Practice assessment is too traditional to offer authentic evaluation for life-long learning. Globally, Teaching Practice is the greatest academic process in training preservice teachers. However, there are concerns raised regarding what is regarded as inadequate teacher preparation, inconsistencies and subjectivity in Teaching Practice assessment, and misalignment between instructional theory and classroom practice have resulted in high demand for quality improvement of the Teaching Practice assessment framework. The research has adopted the post-positivism research paradigm, mixed methods research approach, and the QUAN-QUAL sequential explanatory research design. The population was all Post Graduate students at one university and all Diploma in Education students at on Teachers College in Zimbabwe. Data collection instruments used were: observations schedule, interviews, questionnaires, and documentary analysis. Results have shown that Teaching Practice assessment was of great value for academic, pedagogical, and teacher professional development. Subject content knowledge posed greater challenge to preservice teachers than pedagogical content knowledge during Teaching Practice assessment. School environment, accommodation, lack of material and financial resources, heavy workload, indiscipline, unexpected assessment visits, and contradictions by assessors were major factors that affected Teaching Practice assessment. Pre-service teachers preferred to be assessed by college-based to university-based assessors because they give them feedback for learning, they motivate, and they understand their plight, and they appear more professional in their conduct than university-based assessors. The study therefore suggests a framework for improving the quality of Teaching Practice that includes a balanced curriculum, intensified training on content knowledge and pedagogical content knowledge; a proper collaboration between college and university assessors; training in ICT, and more focused Teaching Practice workload, and the practice of reflective, authentic, and emancipatory assessment practices for sustainable development.
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  • Date Issued: 2020

Promoting leader integrity through the human resource management value chain

  • Authors: De Villiers, Bridget
  • Date: 2020
  • Subjects: Leadership -- South Africa , Leadership -- South Africa -- Moral and ethical aspects Business ethics Professional ethics Personnel management
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/50469 , vital:42197
  • Description: Ethical breaches in the public and private sector in South Africa are prevalent and the effects thereof pervasive on the economy and within broader society. These ethical breaches include corruption, bribery, and the mismanagement of resources and may be attributed to poor decision-making on the part of organisational leaders. The complexity of the circumstances in which organisations operate in the 21st century requires that leaders effectively navigate moral dilemmas while considering the broad range of interests represented by many organisational stakeholders. Leaders need to act in a manner that is ethically sound to avoid the negative consequences associated with unethical organisational conduct, including a loss of profit, credibility and reputation. Ethical leadership is central to moral organisational governance, as compliance with rules and regulations alone is ineffective in building and sustaining an ethical organisation. Literature points to the centrality of leader integrity to the notion of ethical leadership and that an ethical organisational culture is sustained by leaders who possess integrity. In promoting leader integrity studies highlight management interventions and organisational success factors that promote an ethical organisation. Within the context of this study these management interventions and success factors were identified as promoting leader integrity. Further, the literature identified the important role of leaders in supporting these interventions and creating the conditions necessary to foster the success factors. These management interventions are offered through and the success factors are linked to the human resource management value chain. The main aim of this study was to explore the promotion of leader integrity through the human resource management value chain in South African organisations. The main aim of the study led to the development of several theoretical and empirical sub-objectives that were addressed through the following actions: A literature study was conducted examining the nature of ethical leadership and leader integrity and included a consideration of the dark side of leadership. The literature was further examined in relation to the nature of an ethical organisation and organisational integrity, the role of the leader in promoting an ethical organisational culture, and regarding the management interventions and success factors that were seen to promote leader integrity. The insights gained from the literature review assisted in the compilation of a survey questionnaire, this being the Management Interventions and Success Factors Scale. This scale, together with an existing scale, The Perceived Leader Integrity Scale (version 1.2), were used in the empirical study to determine the perceptions of employees as to whether specific management interventions and success factors were seen to promote leader integrity, and the extent to which their managers were seen to act with integrity. These employees worked in the public and private sectors across South Africa, and a final sample size of 606 respondents was achieved. The empirical results of the study revealed that management interventions and success factors were seen to promote leader integrity. However, due to high levels of inconsistency in the responses received it was recommended that a clearer link needs to be created in terms of how the success factors and interventions promote leader integrity. The empirical study further revealed that South African leaders were seen to act with integrity, more especially not to engage in acts of extreme negative deviance such as theft or sabotage, but that there was room for improvement as there were employees who reported moderate and low levels of integrity among their managers. Together with the literature review the empirical study contributed towards the development of a model and a framework for the promotion of leader integrity across the HRM value chain. South African leaders have a crucial role to play in promoting not only the moral fibre of the organisations that they represent, but also in contributing positively to moral regeneration at both a national and a global level through effective and integrity-based organisational governance. This is achieved through adopting an integrated, strategic and holistic approach to the promotion of leader integrity as proposed in this study.
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  • Date Issued: 2020

Promoting leader intergrity through the human resource management chain

  • Authors: De Villiers, Marie Bridget
  • Date: 2020
  • Subjects: Leadersship --Moral and ethical Aspects -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/49791 , vital:41801
  • Description: Ethical breaches in the public and private sector in South Africa are prevalent and the effects thereof pervasive on the economy and within broader society. These ethical breaches include corruption, bribery, and the mismanagement of resources and may be attributed to poor decision-making on the part of organisational leaders. The complexity of the circumstances in which organisations operate in the 21st century requires that leaders effectively navigate moral dilemmas while considering the broad range of interests represented by many organisational stakeholders. Leaders need to act in a manner that is ethically sound to avoid the negative consequences associated with unethical organisational conduct, including a loss of profit, credibility and reputation. Ethical leadership is central to moral organisational governance, as compliance with rules and regulations alone is ineffective in building and sustaining an ethical organisation. Literature points to the centrality of leader integrity to the notion of ethical leadership and that an ethical organisational culture is sustained by leaders who possess integrity. In promoting leader integrity studies highlight management interventions and organisational success factors that promote an ethical organisation. Within the context of this study these management interventions and success factors were identified as promoting leader integrity. Further, the literature identified the important role of leaders in supporting these interventions and creating the conditions necessary to foster the success factors. These management interventions are offered through and the success factors are linked to the human resource management value chain. The main aim of this study was to explore the promotion of leader integrity through the human resource management value chain in South African organisations. The main aim of the study led to the development of several theoretical and empirical sub-objectives that were addressed.
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  • Date Issued: 2020

Psychological and emotional effects of repeated exposure to violent crimes on victims residing in a high crime community in Nelson Mandela Metropolitan in the Eastern Cape

  • Authors: De Klerk, Ulricha
  • Date: 2020
  • Subjects: Post-traumatic stress disorder
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/46413 , vital:39582
  • Description: Traumatic Stress Disorder (PTSD). While the literature provides detailed and comprehensive approaches and counselling modalities to working with clients who experience traumatic events, there is not much evidence on the experiences of individuals who reside in high crime communities. It follows, that the psychological and emotional experiences, as well as needs of such individuals may present with specific requirements from the therapeutic alliance. This study aimed to explore the psychological and emotional effects of repeated exposure to high crime and violence and the implications this posed to traumatic experiences. The study further aimed to develop a set of guidelines that can be drawn upon when working therapeutically with clients who reside in high crime communities. The study draws on a qualitative methodology and 17 participants were interviewed. The transcripts were analysed using thematic analysis and five themes were identified, relevant to the aims and objectives that were set. The findings suggest that the psychological and emotional experiences of individuals who reside in high crime communities, is experienced at a more heightened and prolonged period, thus making the psychotherapeutic intervention employed, more specific. To this effect, the guidelines developed provide specific strategies and approaches thatwere developed based on the themes identified and verified by a panel of psychological experts. The study contributes to the field of trauma, counselling and violence, in that it focuses on an area of trauma that has not been adequately focused on withinthe South African context, as well as in global contexts.
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  • Date Issued: 2020

Quantifying ecosystem restoration recovery and restoration practice following the biological control of invasive alien macrophytes in Southern Africa

  • Authors: Motitsoe, Samuel Nkopane
  • Date: 2020
  • Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/167519 , vital:41488
  • Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
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  • Date Issued: 2020

Radical transformation and sustainability for an advanced manufacturing industry: a progressive model

  • Authors: Noor, Richard , Van der Merwe, Karl
  • Date: 2020
  • Subjects: Manufacturing industries -- South Africa , Leadership Organisational learning
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/46849 , vital:39669
  • Description: The manufacturing industry in one of the most significant contributors to a countries GDP across the world. South Africa is no different and yet it remains an interesting challenge for the country. Power and greed seem to have overtaken the moral fibre of our society and has inflicted pain and suffering to millions across the country. The manufacturing has not been immune to this challenge and appears to be in free fall on so many levels. The primary objective of this research was to develop a model for the manufacturing industry which would assist the role players to navigate the challenges and obstacle in this ever changing and demanding industry. An extensive review of literature was conducted which informed and guided the process of gathering information and data using a questionnaire and a survey conducted across the manufacturing industry. Structural Equation Modelling was used to test the relationships between the various factors identified during the literature review. Leadership Impact was confirmed as a significant contributor as well as the Economic Impact having a significant impact on both Radical Transformation and Sustainability. This study scientifically added to the body of knowledge having taken several factors within the manufacturing industry and analysed its impact on radical transformation and sustainability, the integration of these factors within one study has not been previously conducted and has contributed to the manufacturing industry, business leadership and management fields of study.
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  • Date Issued: 2020

Reef fish associations with benthic habitats at a remote protected coral reef ecosystem in the Western Indian Ocean-Aldabra Atoll, Seychelles

  • Authors: Haupt, Philip
  • Date: 2020
  • Subjects: Coral reef ecology -- Aldabra Islands (Seychelles) , Reef fishes -- Aldabra Islands (Seychelles) , Benthic animals -- Aldabra Islands (Seychelles)
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/141629 , vital:37991
  • Description: The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef.
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  • Date Issued: 2020

Resource Allocation Framework in Fog Computing for the Internet of Things Environments

  • Authors: Vambe, William Tichaona
  • Date: 2020
  • Subjects: Internet of things Cloud computing
  • Language: English
  • Type: Thesis , Doctoral , PhD (Computer Science)
  • Identifier: http://hdl.handle.net/10353/18498 , vital:42575
  • Description: Fog computing plays a pivotal role in the Internet of Things (IoT) ecosystem because of its ability to support delay-sensitive tasks, bringing resources from cloud servers closer to the “ground” and support IoT devices that are resource-constrained. Although fog computing offers some benefits such as quick response to requests, geo-distributed data processing and data processing in the proximity of the IoT devices, the exponential increase of IoT devices and large volumes of data being generated has led to a new set of challenges. One such problem is the allocation of resources to IoT tasks to match their computational needs and quality of service (QoS) requirements, whilst meeting both task deadlines and user expectations. Most proposed solutions in existing works suggest task offloading mechanisms where IoT devices would offload their tasks randomly to the fog layer or cloud layer. This helps in minimizing the communication delay; however, most tasks would end up missing their deadlines as many delays are experienced during offloading. This study proposes and introduces a Resource Allocation Scheduler (RAS) at the IoT-Fog gateway, whose goal is to decide where and when a task is to be offloaded, either to the fog layer, or the cloud layer based on their priority needs, computational needs and QoS requirements. The aim directly places work within the communication networks domain, in the transport layer of the Open Systems Interconnection (OSI) model. As such, this study follows the four phases of the top-down approach because of its reusability characteristics. To validate and test the efficiency and effectiveness of the RAS, the fog framework was implemented and evaluated in a simulated smart home setup. The essential metrics that were used to check if round-trip time was minimized are the queuing time, offloading time and throughput for QoS. The results showed that the RAS helps to reduce the round-trip time, increases throughput and leads to improved QoS. Furthermore, the approach addressed the starvation problem, a phenomenon that tends to affect low priority tasks. Most importantly, the results provides evidence that if resource allocation and assignment are appropriately done, round-trip time can be reduced and QoS can be improved in fog computing. The significant contribution of this research is the novel framework which minimizes round-trip time, addresses the starvation problem and improves QoS. Moreover, a literature reviewed paper which was regarded by reviewers as the first, as far as QoS in fog computing is concerned was produced.
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  • Date Issued: 2020

Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts

  • Authors: Taylor, Richard Peter
  • Date: 2020
  • Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/153746 , vital:39507
  • Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
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  • Date Issued: 2020

Rural enterprise development as a means to poverty alleviation

  • Authors: Bodley, David Cyril
  • Date: 2020
  • Subjects: Rural development -- South Africa , Economic development projects -- South Africa Poverty alleviation -- methods -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/50361 , vital:42118
  • Description: South Africa’s disappointing economic performance over the last decade has resulted in a socio-economic crisis, with unemployment and inequality rates being of the highest rates anywhere in the world. Furthermore, unemployment is concentrated among the young, unskilled, and previously disadvantaged population posing a considerable threat to South Africa’s new democracy. Internationally, a method to absorb job seekers into the economy is to make small business the engine-room of economic growth and development. Consequently, the South African Government has identified in its National Development Plan the establishment of small businesses as a priority, including the development of small businesses in rural and marginalised communities. As rural communities in South Africa experience systemic problems such as the lack of infrastructure, financial capital, skills and potential markets, establishing enterprises in rural settings is often more complex than those more advanced parts of the economy elsewhere where fewer constraints exist. This makes the task of establishing and growing rural entities particularly challenging, suggesting bespoke policy and support is required. This study analyses the literature to gain an understanding of economic development theory and how this intersects with and informs small enterprise development policy. It then looks at South Africa’s strategy and policy framework pertaining to enterprise development. Specifically, the literature examines the role of rural enterprise development to establish whether this enables people to move out of poverty or further entraps people in poverty. The study collates data from a rural and marginalised community through observation and interview techniques. Firstly, multiple in-depth interviews were conducted with nineteen entrepreneurs in a rural community to collect data on business opportunities and explore the type of support entrepreneurs would require from government. Secondly, a focus group interview was conducted with entrepreneurs that had experienced institutional support to understand how well current policy and programmes support rural enterprise development. The primary data was analysed in conjunction with the literature on economic theory and enterprise development using the technique of triangulation to avoid logic leaps and formation of false assumptions. The insights and findings from the analysis reinforced certain facts within the body of knowledge pertaining to enterprise development, but there were also some interesting new insights that emanate from the data. South Africa has been able to introduce a wide range of policy initiatives and has multiple programmes and strategies to support small enterprise development. It has achieved firm success and impetus as well as experiencing certain failures. The study clearly highlights both and makes recommendations to improve policy promoting rural enterprise development as a means to alleviate poverty.
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  • Date Issued: 2020

Socio-ecological, contextual effects in Raven’s Colour Progressive Matrices scores: Developing an index for guiding test selection and interpretation

  • Authors: August, Justin Oswin
  • Date: 2020
  • Subjects: Ecological Systems Theory
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/46401 , vital:39563
  • Description: With the changing landscape in South Africa to a full democracy, increased research has been undertaken in the psychometric field on local and national normative studies regarding various assessment measures. Given that the Raven’s Coloured Progressive Matrices (CPM)is purported to be culture-free and not heavily dependent on verbal and language skills;it has been extensively normed throughout the world for various population groups. While norms for normal populations of children have been developed in South Africa, these studies were based on race and gender predominantly and without taking into consideration the effects of socio-ecological factors on test performance. The research study aimed to understand the influence of socio-ecological factors on the expression of cognitive scores amongst a geographically diverse sample of South African learners. Through this study, research on the interplay between context and cognition was to be located within the Ecological Systems model of Bronfenbrenner. A secondary aim of the study was to develop an index that will guide test selection and interpretation of assessment results, taking into account the influence of socio-ecological factors and providing a conceptual framework for future test development. The study employed a quantitative methodology on a South African sample consisting of primary school children aged between the ages of 6 years to 11 years. The sample was drawn from schools in the Port Elizabeth areain South Africa that wereclassified into low, medium and high opportunity, based on context. The results indicated that the type of school had a significant impact on test performance, suggesting that contextual factors were influential in this process.The item analysisconductedfurther indicated that learners from a low opportunity school performed significantly lower than the other two schoolsin the sample. The index development provides a foundation for further research that would enhance the interpretation of test results. In the South African context, this is considered important, given our political history and our diversity wherea“one size fits all” approach is not possible.
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  • Date Issued: 2020

Strategies for the facilitation of implementation of best practice guidelines in operating theatres at public hospitals

  • Authors: Owolabi, Olukemi Olufunmilayo
  • Date: 2020
  • Subjects: Operating rooms—Safety measures
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/46422 , vital:39594
  • Description: Best practice guidelines (BPGs) are the use of scientific evidence to direct patient care and guide clinical care to integrate best patient outcomes. The implementation of BPGs in operating theatre nursing improves patient safety and quality of care and enhances patient outcomes. Although BPGs are crucial, the implementation thereof is not well operationalised in clinical practice, especially in an area such as the operating theatres in public hospitals in the Nelson Mandela Bay Health District(NMHD)in the Eastern Cape Province. The study thus developed strategies that could be used to facilitate the implementation of best practice guidelines in the operating theatres at public hospitals in the NMBHD. Understanding registered nurses’ knowledge, attitudes, and practices (KAP) with regard to implementing BPGs in the operating theatre is important, as it will assist in the development of strategies to facilitate the implementation of BPGs.The study was conducted in three phases. Phase One comprised of a quantitative approach. Data collection was achieved by means of a self-administered questionnaire which was distributed to registered nurses in the operating theatres of public hospitals in the NMBHD. The purpose of the questionnaire was to establish their knowledge, attitude and practice with regard to best practice guidelines and the implementation thereof. Recommendations made by participants for strategies to facilitate the implementation of BPGs in operating theatres were also explored. Descriptive and inferential statistics were utilised to analyse and describe the data. Descriptive statistics were used to describe the profile of the sample, including the demographic data measures of central tendency, for example the mean and standard deviation (SD) and correlation techniques.Chi²analysis was performed to test for significance of the associations between the registered nurses’ demographic variables and their KAP. Data were categorised into three levels, namely lower (score < quartile 1 i.e. bottom 25%). Middle (quartile1 ≤ score ≤quartile i.e. in the middle 50%) and higher (score > quartile 3 i.e. top 25%).Findings from this research study revealed the limited knowledge, attitude and practice of OT nurses about BPGs. During Phase Two an integrative literature review approach was followed in order to identify the best available evidence with regard to the facilitation of the implementation of best practice guidelines in operating theatres. Lastly, Phase Three: strategies that could be used to facilitate the implementation of best practice guidelines in operating theatres were developed. The researcher developed the conceptual framework using the six elements of Dickoff, James and Weidenbach (1968:422). The conceptual framework informed the development of strategies. The strategies are a synthesis of the conclusions drawn from the research findings (phase one and two) and the conceptualization thereof. The strategies were reviewed by six-panel members. Each panel member was supplied with the format for evaluation of the strategies which was based on the criteria established by Chinn and Kramer (2018:156) the results of which included in chapter 7. The researcher ensured that the data obtained was valid and reliable, necessary to assist the researcher to produce quality research. Ethical considerations were maintained throughout. In general, the results of this thesis indicate that the developed strategies that could be used to facilitate the implementation of best practice guidelines, in operating theatres at public hospitals in the NMBHDare unique and could be implemented in theatres in public hospitals. The researcher succeeded in achieving the purpose for this study, because the strategies which are understandable, clear, simple, applicable and significant to operating theatre unit has been developed for use by operating theatre nurses, to facilitate the implementation of best practice guidelines in operating theatres at public hospitals in the NMBHD.
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  • Date Issued: 2020

Synthesis and characterization of binary and ternary palladium alloys for use as alternative counter electrode catalysts in dye sensitized solar cells

  • Authors: Zingwe, Nyengerai Hillary
  • Date: 2020
  • Subjects: Electrocatalysis Chemistry
  • Language: English
  • Type: Thesis , Doctoral , PhD (Chemistry)
  • Identifier: http://hdl.handle.net/10353/18513 , vital:42580
  • Description: The dye sensitized solar cell counter electrode facilitates the regeneration of the dye molecules thereby ensuring the provision of higher sunlight to electricity conversion efficiency. The standard platinum electrode suffers from low efficiency due to corrosion by the redox mediator as well as being extremely expensive due to high demand. As an alternative this research study illustrates the efforts undertaken to replace the standard platinum counter electrode with palladium alloy counter electrodes. Application of palladium alloys ensures sustenance of high catalytic activity by palladium which is as effective as platinum. Although palladium is equally as expensive as platinum, its application in the form of alloys minimizes the amount required to produce an effective counter electrode to 0.001-0.004 moles thereby ensuring the provision of high efficiency at a lower cost. Furthermore, charge transfer from the other alloyed elements to the palladium atom increases active sites leading to higher catalytic activity than platinum. Additionally, changes in crystal structure due to alloying enhances resistance to corrosion thus enabling the longevity of the alloy counter electrode in the electrolyte ___________________________________________________________________________ Electrochemical analysis was conducted to determine the catalytic functionality of the developed alloys in cobalt, ferrocene and iodine redox mediators. The binary (PdNi-reduced graphene oxide (rGO) and PdCo-rGO) and ternary (PdNiCo-rGO) palladium alloys were fabricated via a hydrothermal method. In order to determine the composition which could provide the maximum activity, optimization was conducted through variation of the molar ratios of the precursor solutions. The properties of the synthesized palladium alloys were determined using various techniques including x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The developed alloys were observed to comprise of palladium, nickel, cobalt, and carbon atoms. The particles were spherical in nature for all the unsupported alloys with the carbon supported alloys exhibiting spherical particle wholly surrounded by graphene sheets. Cyclic voltammetry and electrochemical impedance spectroscopy analysis showed that the carbon supported alloys PdNi-rGO, PdCo-rGO and PdNiCo-rGO produced the highest catalytic activities due to the synergy between their respective alloys and the incorporated reduced graphene oxide. The high catalytic effectiveness of these alloys yielded power conversion efficiency in the order PdNiCo-rGO (9.01) > PdNi-rGO (8.4.%) > PdCo-rGO (6.56%) > Pt (5.7%) which were better than the platinum efficiency in the cobalt redox mediator. The higher efficiency in the cobalt redox mediator relative to the iodine electrolyte illustrates that they are viable alternatives to the, corrosive and volatile iodine. Obtained results show that, the high recombination rates between the photogenerated electrons and the oxidized dye molecule which have been reported to reduce power conversion efficiency in one electron redox mediators did not affect the performance of the cell. However, these higher recombination rates affected the ferrocene electrolyte leading to extremely poor efficiency metrics. The obtained results indicated that reduced graphene oxide supported PdNi-rGO, PdNiCo-rGO as well as the unsupported PdNi3 alloys could successfully be implemented as substitutes to the platinum counter electrode in dye sensitized solar cells. The application of the palladium alloys is vital for improving stability and power conversion efficiency, as well as reducing cost.
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  • Date Issued: 2020

Synthesis of novel heterocyclic systems as potential inhibitors of HIV-1 enzymes

  • Authors: Sekgota, Khethobole Cassius
  • Date: 2020
  • Subjects: Protease inhibitors , Heterocyclic compounds , HIV (Viruses) , Quinoline , Amides , Nuclear magnetic resonance , Antiretroviral agents , AIDS vaccines , Nitrobenzaldehyde , Propylphosphonic acid anhydride
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/146502 , vital:38531
  • Description: This study has focussed on the application of Baylis-Hillman methodology in the development of efficient synthetic pathways to libraries of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones and indolizine-2-carboxamides and on an exploration of their medicinal potential. The approach to 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones involved a six-step pathway comprising: Baylis-Hillman reaction of 2-nitrobenzaldehyde derivatives and methyl acrylate to afford nitro-Baylis-Hillman adducts; thermal cyclisation of the adducts to give a range of 3-(acetoxymethyl)-2(1H)-quinolones in good to excellent yields; hydrolysis of the acetates; conversion of the resulting alcohols to the 3-chloromethyl analogues; amination; and, finally, acylation to afford the target amides. Variable temperature NMR methods were used to facilitate analysis of the ¹H and ¹³C NMR spectra which were complicated by internal rotation and cycloalkyl ring-flipping effects. On the other hand, the indolizine-2-carboxamides were obtained in several steps commencing with the Baylis-Hillman reaction of pyridine-2-carboxaldehyde and methyl acrylate. Thermal cyclisation of the Baylis-Hillman adduct afforded indolizine esters, hydrolysis of which gave the corresponding acids which served as precursors to the target indolizine-2-carboxamides. The final amidation step, however, proved to be particularly challenging. Various coupling strategies were explored to access indolizine-2-carboxamides. These included the use of 2,2,2-trifluoroethyl borate which showed limited promise, but propylphosphonic acid anhydride (T3P) proved to be the most effective coupling agent, permitting the formation of 24 novel indolizine-2-carboxamides from hydrazines, aliphatic amines and a range of heterocyclic amines. A high-field NMR-based kinetic study of the mechanism of the Baylis-Hillman reaction of pyridine-4-carboxaldehyde and methyl acrylate in the presence of 3-hydroxyquinuclidine in deuterated chloroform was initiated, reaction progress being followed by the automated collection of ¹H and DEPT 135 NMR spectra over ca. 24 hours using a high-field (600 MHz) NMR instrument. The results have provided critical new insights into the mechanism. NMR analysis has also been used to elucidate the multiplicity of signals associated with rotameric equilibria observed at ambient probe temperature. Variable temperature 1D- and 2D-NMR spectra were used to facilitate the unambiguous characterisation of the 2-quinolone benzamides and some of the indolizine-2-carboxamides. The 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones, together with selected precursors, and a number of the indolizine-2-carboxamides have been screened in vitro as potential HIV-1 enzyme inhibitors. A survey of the activity of the 2-quinolones against HIV-1 integrase, protease and reverse transcriptase revealed selective inhibition of HIV-1 integrase with the most active IN inhibitor, 3-[(cyclopentylamino)methyl-6-methoxy-2(1H)-quinolone 115e, producing residual enzyme activity of 40% at a concentration of 20 μM. Many of the 2-quinolones exhibited no significant cytotoxicity against HEK 293 cells at 20 μM concentrations. 3-[(N-Cyclohexylamino)methyl]-6-methoxy-2(1H)-quinolone 114e was the only compound to exhibit ant-plasmodial activity (55% pfLDH activity). The survey of indolizine-2-carboxamides also revealed encouraging inhibition against HIV-1 integrase. None of these compounds exhibited cytotoxicity at 20 μM against HEK 293 cells, while a number of them exhibited some activity against Plasmodium falciparum (3D7 strain) and Trypanosoma brucei. Selected indolizine-2-carboxamides exhibited significant anti-tubercular activity in the 7H9 CAS GLU Tx and 7H9 ADC GLU Tw media. In view of the inherent fluorescent character and biological potential of the synthesised indolizine-2-carboxamides, their photophysical properties were explored to establish their possible dual use as bio-imaging and therapeutic agents. The major absorption and corresponding emission bands, and the associated molar absorption coefficients (Ɛ) expressed in the form of log Ɛ were determined. Their high extinction coefficients, large Stokes shift and red-shifted emissions in the visible region indicate their potential for use as fluorophores.
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  • Date Issued: 2020

Synthesis, characterisation and antitumour activities of lanthanide complexes with hydrazones and carboxylic acid ligands

  • Authors: Madanhire, Tatenda
  • Date: 2020
  • Subjects: Organic acids
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/48456 , vital:40878
  • Description: The tridentate hydrazone ligands, (E)-N'-(2-hydroxybenzylidene)benzohydrazide (H2phen) and (E)-N'-(2-hydroxybenzylidene)nicotinohydrazide (H2Nic), were synthesised and complexed to Ln(III) acetates. The centrosymmetric, acetato-bridged dinuclear coordination compounds with the formulae, [La2(Hphen)2(OAc)4(H2O)2]·DMF·H2O (1), [Ln2(HNic)2(OAc)4(H2O)2]·DMF·H2O (Ln = La (2) and Nd (3)) and [Ln2(HNic)2(OAc)4(H2O)2]·DMF (Ln = Er (4) and Yb (5)) were isolated and characterised by elemental analyses, IR spectroscopy, UV-Vis spectroscopy, X-ray diffraction studies and SHAPE 2.1. The nine-coordinate complexes 1–3 crystallise in the triclinic space group P-1, with the metal centres having the distorted spherical capped square antiprism geometry (C4v), while the eight-coordinate Er(III) and Yb(III) complexes (monoclinic system, space group P21/c) display the geometry of distorted triangular dodecahedron (D2d). Geometry optimisation of the monoanionic forms of the hydrazone ligands (Hphen– and HNic– ) were performed using Density Functional Theory (DFT) with Becke’s three parameter hybrid method and correlation functional of Lee, Yang and Parr (B3LYP) with augcc-pVTZ basis set. Natural population analysis (NPA) and molecular electrostatic potential (MEP) maps indicated that the most preferred sites for electrophilic attack in the anionic ligands are the phenolate and carbonyl oxygens, and the azomethine nitrogens. The evaluation of the cytotoxic activity of the compounds on breast cancer (MCF-7), the endometrial carcinoma (HEC-1A) and the human monocytic (THP-1) cell lines using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that the hydrazone ligands and complexes 1–4 are partially cytotoxic against MCF-7 cells, while the Schiff bases and complexes 3–5 significantly inhibit cell growth in HEC-1A cells. The complexation reactions of Ce(III), Nd(III), Gd(III) and Er(III) with the chelating/ bridging monoanionic ligand N-(2,6-dimethylphenyl)oxamate (Hpma– ) in basic media were performed in view of the potential applications of oxamate derivatives as cytotoxic agents. The coordination compounds were characterised by different Abstract T. Madanhire Nelson Mandela University xxvi physico-chemical techniques: elemental analysis, conductivity measurements, IR, 1 H NMR and UV-Vis-NIR spectroscopy. The anionic Hpma– was obtained through conversion of the proligand ethyl (2,6-dimethylphenylcarbamoyl)formate (Hdmp). The reactions afforded lanthanide(III)–oxamate coordination polymers of formulae: {[Ln(Hpma)3(MeOH)(H2O)]∙2MeOH}n (Ln = Ce (1) and Nd (2)), {[Gd2(Hpma)6(MeOH)4]∙6MeOH}n (3), {[Er2(Hpma)6(MeOH)(H2O)3]∙2MeOH}n (4) and [Ln2Na2(Hpma)8(EtOH)(H2O)6]n (Ln = Nd (5) and Gd (6)). The polymeric complexes feature Ln-Hpma moieties bridged by μ2-η 1 :η 1 :η 1 Hpma– , giving onedimensional zig-zag chains of the –Ln–O–C–O–Ln– type. Atomic charge analysis and the MEP map of the Hpma– moiety done using the DFT/B3LYP method were found to be consistent with the chelating and bridging modes of the anionic ligand through all the oxygen atoms. The evaluation of the cytotoxic activities of the metal salts, the proligand and the novel lanthanide complexes on MCF-7, HEC-1A and THP-1 cell lines revealed that only the rare-earth metal salts [Ce(NO3)3∙6H2O] and [Nd(NO3)3∙6H2O] showed modest cytotoxicity against MCF-7 and HEC-1A cells, respectively.
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  • Date Issued: 2020

Synthesis, characterisation and electrocatalytic behaviour of three series of Metal Organic Frameworks

  • Authors: Murinzi, Tafadzwa Wendy
  • Date: 2020
  • Subjects: Electrochemistry , Metal-organic frameworks , Polyoxometalates , Fourier transform infrared spectroscopy , Electrocatalysis , Cysteine
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/167598 , vital:41495
  • Description: Metal organic frameworks (MOFs) have received a lot of attention over the past few years due to their vast range of interesting properties and applications, such as catalysis, environmental sensing and storage. This wide range of potential applications is afforded by careful selection and manipulation of the components chosen in assembling of MOFs. In this study, three series of MOFs were synthesized from Co(II), Cu(II) and Mo(VI) polyoxometallates with either 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid or 2,6- pyridinedicarboxylic acid as the ligands. In series 1, the common 1,3,5- benzenetricarboxylic acid MOF, HKUST-1, and POM modified HKUST-1 compounds involving encapsulation and encorporation of the POM were utilised. In series 2, flexible cobalt(II) benzenepolycarboxylate MOFs which investigated the effect of varying the degree of carboxylate substituent were utilised. In series 3, flexibly reduced heterocyclic polycarboxylate MOFs using 2,6-pyridine dicarboxylate were utilised. Solvothermal and slow evaporation synthesis conditions were employed. Where single crystals of good quality were produced, single crystal X-ray diffraction (SC-XRD) was employed for structural elucidation. In the absence of such crystals, a combination of elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES) and powder X-ray diffraction (PXRD) was used. Characterization of the MOFs was done by Fourier transform infrared spectrometry (FTIR) and thermal methods, namely thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The electrocatalytic potential of the compounds in the oxidation of L-cysteine was then investigated using a variety of techniques. Cyclic voltammetry was used for L-cysteine detection whilst chronoamperometry and differential pulse voltammetry were used to determine the nanoprobes’ sensitivity, rate constants and detection limits. Electrochemical impedence spectroscopy was used to investigate the charge transfer resistance (RCT) and electron transfer kinetics. Of the three, series 3 gave the best signals and sensitivities for electrocatalysis of L-cysteine followed by series 2 and lastly series 1. Series 2 showed the highest stability and series 1 required the least overpotential. The results highlight the effects of different metal centres and ligands on electrocatalysis. The application of MOFs in electrochemistry is a relatively new field making the findings of this study a significant addition to the body of knowledge.
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  • Date Issued: 2020
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