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Evaluating the potential of monometallic and bimetallic nanomaterials as horseradish peroxidase mimetics

- Mvango, Sindisiwe

Authors: Mvango, Sindisiwe
Date: 2017
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/65134 , vital:28694
Description: This study presents the synthesis of citrate-capped gold nanoparticles (cit-AuNPs), copper oxide nanoparticles (CuONPs), glutathione-capped gold nanoparticles (GSH-AuNPs), 4- aminothiophenol-capped gold nanoparticles (4-ATP-AuNPs), 4-mercapto benzoic acid- capped gold nanoparticles (4-MBA-AuNPs) and copper oxide gold nanoalloys (CuO-Au nanoalloys). Microscopy and spectroscopy techniques were used to confirm the successful synthesis of these nanoparticles. The synthesized nanoparticles were studied their potential applications as horseradish peroxidase (HPR) enzyme mimetics and for the detection of glucose. The cit-AuNPs and GSH-AuNPs exhibited peroxidase-like activity towards hydrogen peroxide (H2O2) with high Michaelis-Menten (Km) values of 61.5 mM and 30.8 mM, respectively. The other nanoparticles, that is, 4-ATP-AuNPs, CuONPs and CuO-Au nanoalloys gave lower Km values of 4.74 mM, 1.92 mM and 4.05 mM, respectively. The obtained Km values were comparable to those of HRP enzymes which ranged from 0.214 - 3.70 mM with 4-ATP-AuNPs and CuO-Au nanoalloys slightly higher. These values were within the reasonable experimental values of the HRP enzyme. The studies showed that the gold nanoparticles had low adsorptive efficiency towards H2O2 compared to the copper-based nanoparticles (CuONPs and CuO-Au nanoalloys). The CuO-Au nanoalloys also showed the synergistic effect between the gold and copper nanoparticles with extended linear concentration range for the quantification of H2O2. The mechanism of catalysis was confirmed using UV-vis spectroscopy and electron paramagnetic resonance (EPR) in that the generation of reactive oxygen species was observed. The use of 1,3-diphenylisobenzofuran (DPBF) as radical quencher and 5,5- dimethyl-1-pyrroline N-oxide (DMPO) as a radical scavenger confirmed the production of reductive reactive oxygen species using UV-vis and EPR studies. The rate of production of reactive oxygen species in the gold-based nanoparticles was small compared to the copper-based nanoparticles, that is CuONPs and CuO-Au (bimetallic) nanoalloys. The synthesized nanoparticles were further studied their potential use in the colorimetric detection of glucose. The copper-based nanomaterials, CuONPs and CuO-Au nanoalloys, were excellent towards detection of glucose, with a limit of detection (LoD) of 9.34 pM for CuONPs and 6.75 pM for CuO-Au nanoalloys. The linear concentration (LCR) range of CuONPs was 0 to 70 pM and for CuO-Au nanoalloys the LCR was 0.0 - 30 pM. , Thesis (MSc) -- Faculty of Science, Chemistry, 2017
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Date Issued: 2017

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Outcome and impact assessment in the comprehensive evaluation of rural ICT projects in developing countries

- Mtkoko, Hafeni Tulimewawa Wilhelmina Lyatenda

Authors: Mtkoko, Hafeni Tulimewawa Wilhelmina Lyatenda
Date: 2017
Subjects: Uncatalogued
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/64483 , vital:28548 , DOI 10.21504/10962/64483
Description: Despite existing literature that indicates that Information and communication technologies (ICTs) act as tools for social change and development, there is still limited empirical evidence that demonstrates this. An outcome and impact assessment based on a comprehensive (holistic) evaluation is deemed appropriate at a time when many ICT4D programmes fail to effectively demonstrate their impact towards rural development. A comprehensive evaluation is one that incorporates the evaluation of the need, design, implementation, outcome and impact, efficiency, and scalability of a programme. These stages make up the different domains of an evaluation lifecycle. The following study aims to develop an outcome and impact assessment framework for ICT4D programmes. It forms part of continuous research associated with the development of a rural ICT Comprehensive Evaluation framework. A theoretical approach, using Design Science and Weick’s theorizing process, was applied to investigate the development of a framework (design artefact) for outcome and impact assessment of ICT4D programmes. The theorizing process analysed existing outcome and impact assessment frameworks from social programmes, information systems/technology programmes, and ICT4D programmes. The output of the theorizing process proposes five critical themes of outcome and impact assessment of rural ICT4D programmes that should be assessed. These themes include: Strategic Value, Most Significant Change, Empowerment, Livelihoods, and Sustainability. To assess its utility, the framework was implemented in the Siyakhula Living Lab and Information and Communication Technology for Rural Education (ICT4RED) projects in South Africa. Through the application of the framework in real life ICT4D contexts, the lessons learned contributed to its revision and enhancement. The proposed framework aims to guide evaluators through the assessment of outcomes and impacts in ICT4D programmes. It provides a foundation and justification for the selected outcome and impact assessment themes that contribute to a comprehensive evaluation. An outcome and impact assessment that is informed by: baseline; needs assessment; programme theory assessment; and process assessment data, provides ICT4D evaluators and project stakeholders with meaningful outcome and impact feedback. Having such an approach to outcome and impact assessment ensures that the evaluation process is seen more holistically as part of the ICT4D project as a whole. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2017
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Date Issued: 2017

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An unsung dialogue: music, society and the history of The Flames

- Park, Duncan Keith

Authors: Park, Duncan Keith
Date: 2016
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193645 , vital:45376
Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
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Date Issued: 2016

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Behaviour and trophic ecology of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) associated with floating objects in the open ocean

- Forget, Fabien Rocky Gilbert

Authors: Forget, Fabien Rocky Gilbert
Date: 2016
Subjects: Uncatalogued
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/193531 , vital:45340
Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
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Date Issued: 2016

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Islamic compliant short term insurance: an exploratory study to develop an Islamic compliant insurance model within a South African context

- Jeeva, Shakir

Authors: Jeeva, Shakir
Date: 2016
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193633 , vital:45375
Description: In a world where there is ever increasing risks to be mitigated, either by choice or due to the law of the country, an insurance instrument is the most popular risk mitigation tool. However, from an Islamic perspective, Muslims have certain parameters to adhere to due to the laws and boundaries as set out in the Quraan, as well as the teachings of the final prophet, Prophet Muhammed (Peace Be Upon Him). This has relevance in this context as, according to Islam, the conventional insurance models are in contravention of certain Islamic laws as they contain elements which are not acceptable in the Muslim faith. Therefore, the Islamic insurance models, or Takaful models, have removed the impermissible elements of usury, speculation, and uncertainty, which are all contained in the current conventional insurance models. By removing these impermissible elements from the insurance model, the Takaful model is acceptable for Muslims to use as a risk mitigation tool. The primary aim of the study sought to propose a short term Islamic compliant insurance model within a South African framework. The secondary aims were to ascertain the Islamic requirements for an Islamic insurance model, how these requirements fit into an insurance model, to then compare and contrast the differences between conventional insurance and Islamic insurance and, lastly, to explore awareness and attitudes towards Islamic insurance. Therefore, from the above, a proposed short term Islamic insurance model was developed within a South African context which conforms to the laws and boundaries of Islam, making this insurance model permissible to use as a Takaful tool. Additionally, semi structured interviews were conducted with certain research participants, using purposive sampling, to examine the attitudes and knowledge of the Muslim community towards the Takaful model within a South African context. It was concluded that while the majority of the research participants understand the Takaful model and the significance of this, they have chosen to use the conventional insurance offerings due to the fact that they were unaware of other Takaful alternatives, or due to the fact that the Takaful alternative was out-priced when compared to the conventional insurance offerings. It was therefore concluded that while there is a need for Takaful offerings within South Africa, this must be done in conjunction with additional marketing, education and competitive pricing for potential clients to consider this as an insurance option. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2016
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Date Issued: 2016

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