A case study on the incidence and extent of medullated and coloured fibres in the commercially produced South African wool clip 2010 – 2017
- Authors: Zietsman, Jolandrie
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55445 , vital:52002
- Description: No formal study on the incidence and extent of medullated and coloured fibres has been performed in South Africa. The purpose of this research project was to investigate the validity of the claims that there has been an increase in the production of wool contaminated with medullated and coloured fibres. Therefore, the main aim of this study was to determine whether the incidence and extent of medullated and coloured fibres in the South African wool clip have changed over time. Secondly, the study aimed to determine whether the incidence and extent of medullated and coloured fibres have a distinct geographic distribution. This study explored eight years of wool production records (2010 to 2017) obtained from BKB, the largest wool broker in South Africa. For the purpose of this research, the wool-producing areas of South Africa were divided into 6 regions, according to average annual rainfall, vegetation type and major farming practices applied in the area. Statistical analysis of the data included descriptive statistics, analysis of variance and post-hoc tests, as well as regression analyses. This study succeeded in quantifying the extent and prevalence of contamination with medullated and coloured fibres in the South African wool clip. The overarching conclusions were: • Floating kemp is the most important contaminant of wool in South Africa, with the incidence of harsh kemp and coloured fibres being very low. • Generally, the most important areas that need attention in combatting contamination in the South African wool clip, are the Mixed Farming Summer Rainfall Region, the Semi-Arid Grassveld and the High Rainfall Grassland. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
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- Date Issued: 2022-04
A Combined Experimental and Computational Study of Hydridospirophosphorane Ligand Systems Featuring Halogenated Mandelic Acids
- Authors: Maritz, Marius Johann
- Date: 2023-12
- Subjects: Organic compounds -- Synthesis , Heterocyclic compounds , catalysis -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62096 , vital:71911
- Description: The search for new stereoselective catalysts remains important for the isolation of enantiomeric products from racemic mixtures. The need exists for these catalysts to be more efficient, to be more cost effective as well as be stable over time without undergoing changes in molecular structure and selectivity. The purpose of this research project was to experimentally synthesise and characterise asymmetric catalysts for the use in enantioselective synthesis. The catalysts consisted of the main group element phosphorous as central atom, with the phenyl rings of mandelic acid ligands monosubstituted with halogen atoms fluorine, chlorine and bromine in different configurations. Ligand binding resulted in the formation of hydridospirophosphorane structures, from which the molecular properties and binding geometry of these molecules could be explained by the theory of apicophilicity. Characterization was performed by NMR and IR spectroscopy as well as diffraction studies that provided the experimental crystal structures. The structural, energetic and spectroscopy results were compared to the theoretically obtained molecular properties using DFT analysis. Various interand intramolecular interactions that existed between molecules found in crystal packing environments were discussed. Additional properties that were investigated included modelling solvation effects, molecular orbital analysis, Hirshfeld surfaces, orbital and atomic energy and population analysis as well as ESP energy calculations with the optimized crystal structures as input. Molecular overlay comparisons were also performed between the experimental and optimized structures where the effectiveness of various DFT functionals and basis sets could be determined. The method with the best overall cost-to-accuracy ratio was found to be the triple-zeta def2-tzvp basis set with B3LYP functional theory and the addition of Grimme’s dispersion correction. Results indicated differences in crystal packing depending largely on the given halogen atoms present in the substituted phenyl rings, with differences observed in electronegativity and steric effects. One of the crystal systems showed additional interactions with solvent molecules, giving the impression that obtaining crystal void formation was possible. Alterations in the transition state activation energies between the isomers of each molecule were found to be present and supported the theory behind the mechanism of stereochemical induction. The studied compounds were therefore effective in isolating different enantiomeric ligands by means of energy differences between conformers and displayed unique catalytic properties resulting from the phosphorous main group element. The hydridospirophosphoranes conformers responsible for the lowest theoretically calculated activation energy induced crystallization as was seen by diffraction results for all compounds. Even as an intriguing observation, crystallization will largely depend on solubility rather than a specific conformer’s amount in solution. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
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- Date Issued: 2023-12
A comparison of implementation platforms for the visualisation of animal family trees
- Authors: Kanotangudza, Priviledge
- Date: 2024-04
- Subjects: Business intelligence -- Computer programs , Human-computer interaction , Computer science
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64105 , vital:73653
- Description: Genealogy is the study of family history. Family trees are used to show ancestry and visualise family history. Animal family trees are different from human family trees as animals have more offspring to represent in a family tree visualisation. Auctioneering organisations, such as Boere Korporasie Beperk (BKB), provide livestock auction catalogues containing pictures of the animal on sale, the animal’s family tree and its breeding and selection data. Modern-day farming has become data-driven and livestock farmers use various online devices and platforms to obtain information, such as real-time milk production, animal health monitoring and to manage farming operations. This study investigated and compared two Business Intelligence (BI) platforms namely Microsoft Power BI and Tableau (Salesforce) and the Python programming language used in the implementation of cattle family tree charts. Animal family tree visualisation requirements were identified from analysing data collected from 23 agriculture users and auction attendees who responded to an online questionnaire. The results of an online survey showed that agriculture users preferred an animal family tree that resembled a human one, which is not currently used in livestock auction catalogues. A conference paper was published based on the survey results. The Design Science Research Methodology (DSRM) was used to aid in creating animal family tree charts using Power BI, Tableau and Python. The author compared the visualisation tools against selected criteria, such as learnability, portability interoperability and security. Usability evaluations using eye tracking were conducted with agriculture users in a usability lab to compare the artefacts developed using Power BI and Python. Tableau was discarded during the implementation process as it did not produce the required family tree visualisation The Technology Acceptance Model (TAM) theory, which seeks to predict the acceptance and use of technology based on users' perception of its usefulness and ease of use, was used to guide the research study in evaluating the artefacts. According to TAM, the adoption of the proposed technology to solve the problem of a static animal family tree in livestock auction catalogues was dependent on the agriculture user’s beliefs. This was based upon that the technology would help them make better buying decisions at livestock auctions effortlessly. The other theory used in this study was the Task Technology Fit (TTF). This theory was used mainly to create the task list to be used in the usability test. The results showed that the author of this work and the agriculture users preferred the artefact produced by Power BI. The learnability and development time was shorter and the User Interface (UI) created was more intuitive. The findings of this study indicated that the present auction catalogue could be supplemented using interactive online animal family tree visualisations created using Power BI. This study recommended that livestock auctioneering organisations should, in addition to providing paper catalogues, provide farmers with an online platform to view the family trees of cattle on auction to enhance purchasing decisions. , Thesis (MCom) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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- Date Issued: 2024-04
A data-driven decision-making model for the third-party logistics industry in Africa
- Authors: Moyo, Faith
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53875 , vital:46022
- Description: Third-party logistics (3PL) providers have continued to be key players in the supply chain network and have witnessed a growth in the usage of information technology. This growth has enhanced the volume of structured and unstructured data that is collected at a high velocity, and is of rich variety, sometimes described as “Big Data”. Leaders in the 3PL industry are constantly seeking to effectively and efficiently mature their abilities to exploit this data to gain business value through data-driven decision-making (DDDM). DDDM helps the leaders to reduce the reliance they place on observations and intuition to make crucial business decisions in a volatile business environment. The aim of this research was to develop a prescriptive model for DDDM in 3PLs. The model consists of iterative elements that prescribe guidelines to decision-makers in the 3PL industry on how to adopt DDDM. A literature review of existing theoretical frameworks and models for DDDM was conducted to determine the extent to which they contribute towards DDDM for 3PLs. The Design-Science Research Methodology (DSRM) was followed to address the aim of the research and applied to pragmatically and iteratively develop and evaluate the artefact (the model for DDDM) in the real-world context of a 3PL. The literature findings revealed that the challenges with DDDM in organisations include three main categories of challenges related to data quality, data management, vision and capabilities. Once the challenges with DDDM were established, a prescriptive model was designed and developed for DDDM in 3PLs. Qualitative data was collected from semi-structured interviews to gain an understanding of the problems and possible solutions in the real-world context of 3PLs. An As-Is Analysis in the real-world case 3PL company confirmed the challenges identified in literature, and that data is still used in the 3PL company for descriptive and diagnostic analytics to aid with the decision-making processes. This highlights that there is still room for maturity into using data for predictive and prescriptive analytics that will, in turn, improve the decision-making process. An improved second version of the model was demonstrated to the participants (the targeted users), who had the opportunity to evaluate the model. The findings revealed that the model provided clear guidelines on how to make data-driven decisions and that the feedback loop and the data culture aspects highlighted in the design were some of the important features of the model. Some improvements were suggested by participants. A field study of three data analytics tools was conducted to identify the advantages and disadvantages of each as well as to highlight the status of DDDM at the real-world case 3PL. The limitations of the second version of the model, together with the recommendations from the participants were used to inform the improved and revised third version of the model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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- Date Issued: 2021-12
A methodology for modernising legacy web applications: subtitle if needed. If no subtitle follow instructions in manual
- Authors: Malgraff, Maxine
- Date: 2024-04
- Subjects: Management information systems , Information technology , Application software -- Development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64148 , vital:73657
- Description: One problem faced in the Information Systems domain is that of poorly maintained, poorly documented, and/or unmanageable systems, known as Legacy Information Systems (LISs). As a result of the everchanging web development landscape, web applications have also become susceptible to the challenges faced in keeping up with technological advances, and older applications are starting to display the characteristics of becoming Legacy Web Applications (LWAs). As retaining business process support and meeting business requirements is often necessary, one method of recovering vital LWAs is to modernise them. System modernisation aims to recover business knowledge and provide an enhanced system that overcomes the problems plagued by LISs. When planning to modernise an LWA, guidance and support are essential to ensure that the modernisation exercise is performed efficiently and effectively. Modernisation methodologies can provide this required guidance and support as they provide models, tools and techniques that serve as guiding principles for the modernisation process. Although many modernisation methodologies exist, very few offer a comprehensive approach to modernisation that provides guidelines for each modernisation phase, tools to assist in the modernisation and techniques that can be used throughout. Existing methodologies also do not cater for cases that include both the LWA and migration to modernised web-specific environments. This research study aimed to investigate modernisation methodologies and identify which methodologies, or parts thereof, could be adapted for modernising LWAs. Existing methodologies were analysed and compared using the definition of a methodology, as well as other factors that improve the modernisation process. Modernisation case studies were reviewed to identify lessons learned from these studies so that these could be considered when planning an LWA modernisation. The ARTIST methodology was the most comprehensive modernisation methodology identified from those researched and was selected as the most appropriate methodology for modernising an LWA. ARTIST was modified to the mARTIST methodology to cater for web-based environments.mARTIST was used to modernise an existing LWA, called OldMax, at an automotive manufacturer, anonymously referred to as AutoCo, to determine its ability to support the modernisation of LWAs. Additional tools and evaluation methods were also investigated and used in place of those recommended by ARTIST, where deemed appropriate for the modernisation of OldMax. Limitations set by AutoCo on the hosting and technical environments for the modernised application also required ARTIST to be adapted to better suit the use case. The steps taken during this modernisation were documented and reported on to highlight the effectiveness of mARTIST and the tools used. The result of this modernisation was that the modernised web application, ModMax, was evaluated to determine the success of the modernisation. The modernisation of OldMax to ModMax, using the mARTIST methodology, was found to be successful based on the criteria set by the ARTIST methodology. Based on this, mARTIST can successfully be used for the modernisation of LWAs. To support future modernisations, an evaluation method for determining technical feasibility was developed for LWA, and alternate tools that could be used throughout modernisation exercises were recommended. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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- Date Issued: 2024-04
A model for measuring and predicting stress for software developers using vital signs and activities
- Authors: Hibbers, Ilze
- Date: 2024-04
- Subjects: Machine learning , Neural networks (Computer science) , Computer software developers
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63799 , vital:73614
- Description: Occupational stress is a well-recognised issue that affects individuals in various professions and industries. Reducing occupational stress has multiple benefits, such as improving employee's health and performance. This study proposes a model to measure and predict occupational stress using data collected in a real IT office environment. Different data sources, such as questionnaires, application software (RescueTime) and Fitbit smartwatches were used for collecting heart rate (HR), facial emotions, computer interactions, and application usage. The results of the Demand Control Support and Effort and Reward questionnaires indicated that the participants experienced high social support and an average level of workload. Participants also reported their daily perceived stress and workload level using a 5- point score. The perceived stress of the participants was overall neutral. There was no correlation found between HR, interactions, fear, and meetings. K-means and Bernoulli algorithms were applied to the dataset and two well-separated clusters were formed. The centroids indicated that higher heart rates were grouped either with meetings or had a higher difference in the center point values for interactions. Silhouette scores and 5-fold-validation were used to measure the accuracy of the clusters. However, these clusters were unable to predict the daily reported stress levels. Calculations were done on the computer usage data to measure interaction speeds and time spent working, in meetings, or away from the computer. These calculations were used as input into a decision tree with the reported daily stress levels. The results of the tree helped to identify which patterns lead to stressful days. The results indicated that days with high time pressure led to more reported stress. A new, more general tree was developed, which was able to predict 82 per cent of the daily stress reported. The main discovery of the research was that stress does not have a straightforward connection with computer interactions, facial emotions, or meetings. High interactions sometimes lead to stress and other times do not. So, predicting stress involves finding patterns and how data from different data sources interact with each other. Future work will revolve around validating the model in more office environments around South Africa. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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- Date Issued: 2024-04
A model to predict the development of preeclampsia in South African women
- Authors: Smith, Nathan
- Date: 2022-12
- Subjects: Medical instruments and apparatus -- Design and construction , Hypertension in pregnancy -- measurements-- South Africa , Fetus -- Physiology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59980 , vital:62724
- Description: Preeclampsia is the new onset of hypertension and is one of the leading causes of maternal mortality in South Africa and the world. Preeclampsia is usually diagnosed after 20 weeks’ gestation. Due to South Africa’s poor level of antenatal care, the prediction of pregnant women at risk of developing preeclampsia can be an essential component of improving the level of antenatal. This study used an antenatal care dataset from a South African obstetrician. A review of the literature and existing systems was conducted to identify the eight risk factors. These risk factors are systolic blood pressure, diastolic blood pressure, maternal age, body mass index, diabetes status, hypertension history, nulliparity, and maternal disease. This study used antenatal care datasets from a South African obstetrician. Two models were developed that could accurately predict the development of preeclampsia, one before 16 weeks’ gestation and the other within three check-ups. The model was evaluated using five evaluation metrics: classification accuracy, area under the curve, precision, recall and F-Score. The results of this study show a promising future for the use of machine learning models in health care. To the researcher’s knowledge, this model is the first machine learning model for predicting preeclampsia using a South African dataset. Future work will revolve around validating the model on data collected from field studies in hospitals and clinics around South Africa , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
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- Date Issued: 2022-12
A process for integrated fitness and menstrual cycle data visualisations
- Authors: Taljaard, Isabelle
- Date: 2024-04
- Subjects: Human-computer interaction , Personal information management , Medical informatics -- Standards
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64379 , vital:73689
- Description: The increase in female participation in sport has led to an increase in research reporting on the relationship between fitness and menstrual cycle (F&M) data. Fitness variables such as VO2 max and heart rate are influenced by menstrual hormones and change with the different phases of a cycle. People frequently track both their F&M data, to understand their long-term activity and their body’s changes during the different cycle phases. Both these data sets are tracked and visualised separately to help people understand their data, however little work has been done to visualise the relationship between the two data sets. A process that guides the creation of an integrated F&M visualisation does not exist. This research aimed to develop and adopt a process that could be used to successfully guide the creation of an integrated F&M visualisation. The study followed the Design Science Research Methodology (DSRM) to create a primary and secondary artefact – the process and instantiation thereof. The DSRM was applied in iterative cycles where the process was developed, instantiations created and evaluated by participants. To develop the process, existing data processing and visualisation processes were reviewed from literature, to assess their successes and shortcomings. The review of existing processes revealed what steps, and factors related to those steps, would need to be considered. The process review highlighted the importance of five process steps: planning, collection, access, integration, and visualisation. Once the conceptual process was designed, it was adapted for the goal of creating an integrated F&M data visualisation. Prior to implementation, the process was first tested in a pilot study to ensure its validity before involving participants in data collection. After the process pilot study, the final implementation of the process took place and participants were recruited. In the first step of the process, the different fitness data types that are influenced by the menstrual cycle, and vice versa, were identified through a literature review. In the second step, devices to be used for data collection were evaluated and tested through exploratory testing and review of user manuals available online. The third and fourth steps, access, and integration were informed by further exploratory testing and review of relevant literature. The fifth step, data visualisation, was guided by relevant studies, Hick’s law, and the Schema Theory. Two Iterations of DSR were conducted in two phases. Phase 1 (P1) was the instantiation of the planning, collection, access, and processing steps. Participants wore smartwatches while going about their daily lives and working out and tracked their menstrual cycle to collect data. P1data was used to create several instantiations of the process. The second phase (P2) was the instantiation the visualisation step. The final visualisations, resulting from the instantiations, were evaluated by participants in P2. The review notes were used to improve both the process and the final visualisations. Both P1 and P2 were repeated (iterated) twice. The recommended process can be used by anyone who wants to create an integrated F&M visualisation and was designed to be modular so that users could choose to follow the whole process or only specific steps. The findings of this research can provide guidance to users, developers and smartwatch manufacturers of what people’s preferences are for these integrated visualisations. It also provides guidance for those who wish to create their own visualisations without needing prior programming experience or knowledge, since easy to use, online visualisation tools are recommended. The process instantiations will assist people, especially women, to better understand their menstrual cycle and how it affects their physical well-being. , Thesis (MCom) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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- Date Issued: 2024-04
A spatial assessment of riparian vegetation density and implications for streambank erosion in relation to land tenure in the Mgwalana Catchment, Eastern Cape Province, South Africa
- Authors: Maxama, Asakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53864 , vital:46026
- Description: Riparian vegetation provides an array of various ecosystem functions and has significantly shaped the conditions of catchments. It has strong controls on fluvial geomorphology and erosion processes. The Mgwalana catchment has been intensively studied over the years and the current environmental condition of the study has been linked to land use history. The catchment has been subjected to land use/cover changes (LUCC) over the years. However, spatial variations in riparian vegetation, their implications for stream bank stability and the contribution of land tenure systems to stream channel degradation are poorly understood. The study sought to assess the implications of the spatial variations in riparian vegetation density for stream bank erosion in relation to land tenure on a catchment scale. Land tenure units comprising the catchment of study are traditional and betterment villages (communal lands), and former white commercial farms. A three-pronged approach using GIS and remote sensing, field investigations and laboratory procedures for soil analysis was employed in this study. Variations of riparian vegetation density in the catchment were mapped using ArcGIS for the two land tenure units to assess the spatial variations of riparian density along stream reaches and to determine the spatial relationship between land tenure units and riparian vegetation diminution. Other mapped shape files include sediment accumulation zones to analyse the spatial relationship between riparian vegetation density and sediment sinks. LUCC classification and analysis of the Normalized Difference Vegetation Index (NDVI) were carried out in IDRISI Selva, using Landsat 8 TM imagery of 2018 to represent the current spatial riparian vegetation variations in the catchment. Field investigations were conducted to determine the coupling among hillslope gully erosion, riparian vegetation density and sink areas; and to assess physical characteristics of soil. This would permit an assessment of the implications of riparian vegetation for stream bank erosion and sediment accumulation within the tenure units. Soil samples were taken from scantily and densely vegetated stream reaches, as well as measurements of channel widths and depths. Analyses of soil physical properties viz; grain size distribution, bulk density, soil texture and aggregate stability were done. Results demonstrated that a sparse riparian vegetation distribution was consistent with the communal villages, confined to the upper catchment area. Dense riparian vegetation distribution was consistent with former commercial farms in the lower catchment area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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- Date Issued: 2021-12
A study of the airflow on the windward slope of a transverse dune in the Alexandria coastal dunefield
- Authors: Burkinshaw, Jennifer Ruth
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52734 , vital:43883
- Description: Our understanding of the evolution of dune morphology has been hampered by a lack of empirical observations of airflow behaviour over dune forms. Sand dunes intrude into the atmospheric boundary layer and convergence of streamlines results in an acceleration of airflow up the windward slopes of dunes. This study examines the airflow structure and corresponding bedform development on the windward slope of a 7 m high transverse dune on the edge of the Alexandria coastal dunefield, Algoa Bay, South Africa. The Alexandria dunefield is subjected to a trimodal wind regime, consisting of the dominant south-westerly which blows all year round, summer easterlies and winter northwesterlies. The morphology of the study dune, Dune13, is controlled by the easterlies and north-westerlies, and reverses seasonally with respect to these two winds. Seven section lines 30 m apart and normal to the dune crest were surveyed regularly over the period of a year to monitor the reversal process. Three detailed topographic surveys were also done during this period. Airflow behaviour was monitored during the year. Wind speed profiles on the windward slope of the dune were measured using 4 to 5 vertical arrays of anemometers positioned from the base of the dune to the crest on a 1 selected section line. Usually 4 to 5 anemometers were deployed in each vertical array, from a height of 6 to 10 cm above the surface, up to a height of 150 cm above the surface. Initially 8 microanemometers were available; ultimately 28 anemometers were run simultaneously. An independent weather station at an elevation of 6 m recorded the unaccelerated flow. Local gradient measurements and erosion and deposition rates were recorded along selected section lines. Strong summer easterly winds (14 m/sec at 1.4 m above the dune crest) were measured on a dune slope in the process of being transformed from a slipface to a stoss slope. The following winter, light north-westerly winds (typically B m/sec at 1.6 m above the dune crest) were measured on the new windward slope already reversed by the prevailing winter wind. Airflow data confirm the compression of airflow against the windward slope resulting in a non-logarithmic wind speed profile. Compression results in an increased shear velocity within 30 cm of the dune surface, and the dune slope is eroded. Higher up in the wind speed profile, shear velocity decreases to 0.1 m/sec. It is not known at what height the wind speed profile recovers from the intrusion of the dune into the boundary layer. High values of shear velocity (1.6 m/sec) above the rounded crestal area of the dune record the recovery of the wind speed profile from flow divergence, which is a response to the rapid reduction of dune gradient and is accompanied by deposition of sand in this region. 2 The erosion pin data act as a simple and sensitive test for changes in gradient, reflecting the dune's response to changes in the airflow regime. The shape of the dune plays a major role in determining the extent of the compression and the distribution of shear velocity up the slope. Increased shear velocity is experienced on that part of the slope which is nonaerodynamic with respect to the prevailing wind. Under unidirectional conditions, feedback between flow and form results ultimately in a slope with a curvature such that shear velocity increases systematically upslope. The survey data and erosion pin data record the reversal process as the dune achieves a new steady state during each wind season. The existence of a non-logarithmic wind speed profile makes it difficult to know what relevant measure of shear velocity is to be used in sand transport equations. Future work should include wind speed measurements within 10 cm of the surface. An ideal study modelling aeolian bedform development would utilise wind tunnel measurements, combined with field measurements such as obtained in this study, for comparison with numerical modelling. The study needs to be extended to 3-dimensional airflow measurements. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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- Date Issued: 2021-04
A value alignment smart city stakeholder model
- Authors: Van der Hoogen, Anthea Vivian
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54129 , vital:46309
- Description: The concept of a Smart City has evolved over the last three decades and has attracted the increasing interest of the scientific research community. Unfortunately, many Smart City projects and initiatives do not provide the value expected by all the stakeholders. Many of the reasons for this relate to a lack of data management, data integration, data access and stakeholder participation. People are an integral part of any city’s ecosystem, and the Smart City concept was introduced to address the challenges of an ever-growing global population leading to the risk of depletion of economic, environmental and social resources. The problem addressed in this study is based on the challenges preventing the creation of the value of smart cities or stakeholders. Limited research has been published on the status of Smart City initiatives or on the impact of various success factors on the potential value creation for stakeholders including citizens. Studies on initiatives in developing countries, such as South Africa are even less. Whilst some challenges and constraints related to smart cities in Africa have been reported, there are no studies reporting on initiatives across the data value chain that consider all types of stakeholders, nor the impact of these initiatives. This study addressed this gap in research and designed a theoretical Value Alignment Smart City Stakeholder (VASCS) Model based on a Systematic Literature Review and a review of related theories. The model has important components that should form part of any Smart City project or Smart City initiative. These five main components are: 1) nine Smart City dimensions with related success factors; 2) four stakeholder roles (enablers, providers, utilisers and users); 3) the data value chain; and 4) the five phases of stakeholder benefits/value realisation that can be linked to; 5) stakeholder value alignment. This study applied the VASCS Model to Smart City initiatives in two case studies in the Eastern Cape Province of South Africa, which were the Nelson Mandela Bay and Buffalo City to investigate and understand the status of such initiatives and the alignment of value thereof. The stakeholder interviews were conducted in two rounds with various stakeholders of Smart City initiatives, referred to as cases in the two case studies. An expert review of the VASCS Model was conducted with eight experts in the field of Information Systems and Smart Cities. The findings of this review served to confirm the components of the model, with only minor improvements recommended. It was confirmed that all of the components need to be considered in planning Smart City projects. The first round consisted of six interviews with enablers and providers and the second round consisted of 22 interviews with users, utilisers and citizens. The interviews investigated the value and impact experienced by stakeholders of these initiatives, with a particular focus on the users, utilisers and citizens of the cases. The interview data was transcribed and qualitatively analysed by using Atlas.tiand Excel. The data was analysed according to the Technological, Organisational and Environmental theory constructs and other identified themes. The interview analysis findings revealed several drivers for these initiatives, which were primarily cost reduction, integration and quality assurance. The results also highlighted access to resources, such as technical skills as a challenge. Another challenge identified was connectivity related to access to data and the digital and physical divide that can impact decision making. The main benefits of Smart City initiatives highlighted were the provision of infrastructure, education and training and digitalisation. The theoretical contribution of this study is the VASCS Model, which can assist other researchers and practitioners with knowledge of the factors, drivers, challenges and value obtained in Smart City initiatives. The model has two supplementary components: A Stakeholder Classification Model and a Smart City Success Factor Evaluation Template. The practical contribution of this study is the potential use of the VASCS Model by practitioners, city management, researchers and other stakeholders, who can use the model, with the related model and template for planning and evaluating Smart City initiatives. The model can be used to classify the digital activities according to a Smart City’s success factors while evaluating the value created by these activities. The impact of these initiatives can then be assessed through value realisation and alignment for stakeholders. The scientific contribution is the adoption of the model to the cases in the Eastern Cape. To reveal in depth, rich, interview findings that provide important lessons learnt relating to the value created for the stakeholders and the addition of these findings to the body of knowledge. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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- Date Issued: 2021-12
An architecture for feedback-driven learning analytics
- Authors: Winfield, Philip John
- Date: 2023-12
- Subjects: Educational statistics -- Data processing , Education -- Research -- Statistical methods , Teacher-student relationships
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62744 , vital:72935
- Description: Feedback from students provides an opportunity to gain insights into students’ learning behaviour and participation in higher education learning and teaching. Academic staff are expected to constantly review and improve the learning and teaching environment where feedback contributes vital information toward pedagogical decision-making. Reviewing student feedback is essential but time-consuming, making it crucial to explore more effective and efficient ways to analyse and present feedback that encourages intervention and support. The general design science research evaluation pattern guided the construction and evaluation of a Feedback-Driven Architecture (FDA) for Learning Analytics (LA) to address this problem. An FDA implementation using a suitable case demonstrated each component validating the feasibility and effectiveness of the proposed design. The components identified for inclusion in the FDA were integrated within layers of a three-tiered architecture pattern. The data layer incorporates the collection, preparation and storage of learning management system data which includes free-form narrative student feedback. The application layer contains logic to support the analysis of free-form narrative student feedback and extraction of learning analytics. Arrangement and visualisation of information in the presentation layer aim to promote appropriate intervention and support. Evaluation using a case study showed that the FDA provided necessary guidelines for developing an implementation that produced feedbackdriven learning analytics. Data preparation transformed unstructured data into a suitable representation for effective analysis. Cohorts within narrative feedback responses were identified using the k-means clustering algorithm and latent Dirichlet allocation. Logistic regression and support vector machines were applied as predictive models and trained using extracted quantitative markers to predict academic success. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2023
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- Date Issued: 2023-12
An assessment of different methods for measuring mammal diversity in two Southern African arid ecosystems.
- Authors: Burt, Chloe
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52338 , vital:43591
- Description: A current critical environmental problem is the loss of biodiversity. To allow for adaptive management and effective conservation interventions, reliable data needs to be readily available and effectively collected. To gather reliable data, the most appropriate method must be used. The aim of this thesis was to compare the effectiveness and efficiency of different mammal diversity sampling techniques, including discussing specificities and complementarity of each. I also assessed the limitation of methods in terms of the influence of species traits on detectability. I used standard mammal field methods such as block transects, camera traps, track plates, spotlight surveys, mist nets, acoustic surveys, and live traps for a wide range of mammal taxa, and also included the use of local knowledge in the comparison. I assessed the cost-efficiency of each method by determining the cost per species. The efficiency of each method was assessed by observing when the species accumulation curve reached an asymptote. The effectiveness was determined by the species richness and the taxonomic groups the method detected. My results indicated that block transects were the most efficient and effective method to assess species richness. However, a combination of methods allowed for a more comprehensive survey and my results indicate that block transects and live traps were the best combination. It is important to note, not only the effectiveness and efficiency of methods be assessed, but also their limitations. I therefore also assessed the influence of species traits on the detectability of five methods. The species traits that I tested were body size, diet, activity, and if they lived in groups. On both study areas, body size was the main trait that influenced detectability with most field methods. Diet and activity had varying influence on detectability depending on the method. Group living did not significantly influence detectability. Based on my results, I provide guidelines for choosing the most appropriate survey method for targeted studies on mammals in arid ecosystems as well as guidelines for choosing the most appropriate methods for a terrestrial mammal inventory. Survey methods selection and guidelines provided here can allow for effective monitoring and therefore effective and adaptive management and having reliable and repeatable outcomes from surveys. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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- Date Issued: 2021-04
An evaluation of hibiscus sabdariffa gold nanoparticles for the treatment of triple negative breast cancer
- Authors: Reddy, Nireshini
- Date: 2022-12
- Subjects: Breast--Cancer--Treatment--Technological innovations , Nanomedicine – South Africa , Roselle
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59945 , vital:62697
- Description: Cancer is responsible for the millions of deaths worldwide every year, being ranked as the second leading cause of mortality in the world. Triple negative breast cancer (TNBC) is the most severe type of breast cancer, as it is the most aggressive and difficult to treat. Current treatment methods involve surgery, hormonal-, radiation- and chemotherapy. These are costly and often have severe adverse effects. There has been increasing research in the development of alternative treatment methods to reduce the side effects of cancer therapeutics, as well as the cost. The rapidly growing field of nanotechnology has allowed for the incorporation of several diagnostic, targeting, and therapeutic agents into nanomaterials for cancer treatment. The application of gold nanoparticles (AuNPs) in the diagnosis and treatment of various types of cancers has been widely investigated. AuNPs vary in size, shape, and structure, allowing for the development of diverse formulations for various treatments. The use of green materials, particularly plant material, to synthesise nanomaterials has allowed for the safe, cost-friendly and eco-friendly production of AuNPs that can be used to treat TNBC. The aim of this study was to evaluate the efficiency of green AuNPs synthesised with Hibiscus sabdariffa to treat TNBC in a pilot murine model. Spherical AuNPs were synthesised using an aqueous extract of the calyces of this plant. The AuNPs were characterised using UV-Vis spectrometry, dynamic light scattering, high resolution – transmission electron microscopy, and in vitro stability testing. A cell viability assay showed that these AuNPs exhibited cytotoxicity towards E0771 cells in a dose-dependent manner, where cells treated with the highest concentration of AuNPs (250 µg/mL) exhibited the lowest cell viability (7%). During the in vivo pilot study, C57BL/6 mice were inoculated with TNBC using the E0771 cells. It was found that TNBC had rapidly spread, resulting in metastasis in the liver, as well as omentum and mesentery. This resulted in a number of mice dying; therefore, shortening treatment time of the AuNPs. It is suggested that AuNP treatment may have exacerbated mouse death by promoting ROS production in metastasised tissue, suggesting that AuNP treatment may not be suitable for stage 4 TNBC. Tumor analysis of caspase-3 content showed that the AuNPs exhibited potential pro-apoptotic activity in the tumours, prompting further research into the tumour uptake and apoptotic mechanism of these AuNPs. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
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- Date Issued: 2022-12
An evaluation of the effectiveness of area-based conservation intervention in avoiding biodiversity loss in South Africa
- Authors: Van Straten, Maurice Oswald
- Date: 2023-04
- Subjects: Soil conservation -- South Africa , Livestock farms – South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61132 , vital:69765
- Description: Habitat degradation, livestock farming, crop cultivation, rangeland overutilization and veld mismanagement are among the factors causing biodiversity loss worldwide. Rangelands in arid and semi-arid environments are no exception, as they are under stress from conversion into cropland and pressure from livestock farming. In these arid areas, rainfall is unpredictable and plant recruitment levels low, resulting in veld rehabilitation being a potentially expensive and time-consuming undertaking for landowners. Landowners implement different rehabilitation methods to increase overall vegetation cover and prevent further soil and vegetation degradation. These rehabilitation methods may include the creation of micro-catchments, mulching, brushpacking, ripping, geotextiles, stone cobbling and erosion control fences, individually or in combination with the addition of reseeding, replanting, and use of manure or fertilizer to supplement land rehabilitation. This study investigated the significance of three rehabilitation methods (hollows, brush packing and a combination of these two methods) on water infiltration rates, soil moisture content, and vegetation canopy cover with associated growth form canopy cover over a period of 17 months (March 2021 to August 2022). This study showed that rehabilitation methods implemented had no significant impact on water infiltration rates and vegetation canopy cover. However, rehabilitation methods had a significant impact on soil moisture content. The use of a hollows is recommended when attempting to increase the soil moisture content percentage when performing rehabilitation. Overall vegetation canopy cover is influenced more by seasonal changes than by the rehabilitation methods implemented. This study indicated that the creation of micro-catchments is an effective rehabilitation method to use in an arid area, as it promotes vegetation establishment and growth. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science and Management , 2023
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- Date Issued: 2023-04
An evolutionary algorithm approach to ecological optimal control problems
- Authors: Westcott, Amy-Rose
- Date: 2022-04
- Subjects: Mathematical optimization -- South africa , Evolutionary programming (Computer science)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55544 , vital:52812
- Description: There are several challenges associated with applying conventional (hereafter classic) optimal control (OC) methods to ecological optimal control problems (OCPs). Conditions required by these methods, including differentiability and convexity, for example, are not always met, and ecological problems do not always adhere to solvable OCP formulations. Moreover, mathematically optimal solutions do not always translate to optimal ecological strategies in practice. Despite this, alternative OC approaches are relatively under-explored. Evolutionary algorithms (EAs) circumvent many of the complex aspects of classic OC methods and have been successfully applied to diverse OCPs. Nevertheless, EAs have sel dom been applied to ecological OCPs. The viability of an EA approach to ecological OCPs was therefore investigated in the current study, facilitated by four case studies of increasing complexity and a genetic algorithm (GA) as a representative EA approach. To ascertain the accuracy of a GA approach, comparisons between a GA and classic OC methods were conducted in the first three case studies. The GA generated near-optima in these comparisons, comparable to the corresponding classical solutions, whilst avoiding non-trivial mathematical theory. Supported by these results, an unconventional OCP, that arguably cannot be solved using classic OC methods, was formulated in the fourth case study, and solved using a GA approach. The resulting solution was feasible and further conformed with strategies found to be successful in practice. Additionally, the GA approach was rela tively simple to apply in all case studies. These collective outcomes of demonstrated the viability of a GA as an OC method in eco logical OCPs, thereby supporting the use of an EA approach as an alternative to classic OC methods in ecological OCPs. The feasibility of an EA approach to atypical OCPs was further demonstrated, which may act to increase realism in OC applications. Further investigation in this regard is thus warranted by this study. , Thesis (MS) -- Faculty of Science, Mathematics and Applied Mathematics, 2022
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- Date Issued: 2022-04
An in vitro evaluation of the anti-breast cancer activity of Nigella sativa extracts and its bioactive compound in combination with curcumin
- Authors: Botha, Susanna Gertruida
- Date: 2024-04
- Subjects: Herbs -- Therapeutic use , Radiation-protective agents , Breast -- Cancer -- Treatment
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63639 , vital:73571
- Description: Breast cancer constitutes 23% of all cancers in South African females. Curcumin and Nigella sativa have anti-cancer, anti-metastatic and antioxidant-properties and may be effective against breast cancer. This study focused on the effect of N. sativa extracts or thymoquinone and curcumin, individually and in combination, on breast cancer cells. An MTT assay showed that curcumin reduced cell viability by 50% (IC50) at 18 ± 2.63 μg/mL and thymoquinone (TQ) at 5 ± 0.95 μg/mL against the MDA-MB-231 cells. The IC50 values for curcumin and TQ were 35 ± 6.98 μg/mL and 4 ± 0.96 μg/mL against the MCF-7 cells, respectively. The IC50 value for the NSBE was determined to be 350 ± 55 μg/mL. The IC50 value of NSAE did not fall within the selected concentration range. Synergism was noted for combinations of NSBE with curcumin, and combinations of TQ with curcumin, against both MCF-7 and MDA-MB-231 cells. Two synergistic combinations per treatment per cell line, as determined by the combination index analysis, were chosen for further investigation. The combinations and individual treatments tested against the MCF-10A cells, were not significant, except for NSBE80:CURC20 combination. Curcumin had the most significant anti-oxidant activity; however, no link was noted between the anti-oxidant activity and the cytotoxicity of the combinations. The combination treatments induced apoptosis more effectively than the individual treatments. Caspase-3 dependent apoptosis was noted for NSBE10:CURC90 and TQ80:CURC20 combinations against the MDA-MB-231 cells, and the TQ60:CURC40 combination against the MCF-7 cells. The individual and combined treatments effectively reduced MDA-MB-231 cell adhesion to fibronectin, but not all reduced the cell adhesion to laminin. Based on these results, the combinations of curcumin with TQ or NSBE, have promising anticancer benefits against breast cancer. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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- Date Issued: 2024-04
An investigation into the effects of nano-carbons on the negative electrode morphology of lead acid batteries under high rate partial state of capacity cycling
- Authors: Bolo, Lukanyo
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53324 , vital:45132
- Description: New technological developments in the field of Hybrid Electric Vehicles (HEV’s), vehicle stop-start applications and electrical power utility devices have brought about new demands on the use of energy storage devices such as the Pb-acid battery. These applications require a new understanding and research into the material chemistry of the battery where it has to functionin a Partial State of Capacity Cycling (PSoCC) or High Rate Partial State of Capacity Cycling (HRPSoCC)duty. The Pb-acid battery is well known for its use in the automotive industry where it had worked for decades as a typical Starter, Lighting and Ignition (SLI) power source. However, the conventional Pb-acid battery is not suitable for the new types of vehicle demands and applications. When the Pb-lead acid battery is subjected to PSoCC conditions, very quickly excessive amount of non-conducting PbSO4crystals are formed on the negative plates of the battery that then drastically reduce its useful life in application. Over the years, researchers have shown that the small addition of certain carbon types to the negative plate active material (NAM) during battery manufacturing can reduce the sulfation effect thereby increasing its use the modern vehicle applications. This study investigated industrial manufactured cells that contained up to 0.5 % by weight two types of carbons in the NAM. These were compared to standard built cells in terms of their standard achievable capacities at various rates, their Cold Cranking Ability (CCA), their Dynamic Charge Acceptance (DCA) and a simplified PSoCC test. The carbons were classified as an activated carbon and a carbon nano-fiber and were included as a dry weight additive during the standard paste manufacturing process of the negative plate. Cells were built with a 9-plate configuration using standard expanded grid positive plates with a nominal rated capacity of 36 Ah. The cells were formed and subjected to a number of electrochemical tests, of which selected negative plates were then studied using Scanning Electron Microscopy (SEM) and Electrochemical in-situ Atomic Force Microscopy (EC-AFM). The microscopic study was then used to try and relate the observed material characteristics of the NAM with the carbons to the electrochemical results observed when testing a built cell. , Thesis (MA) --Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
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- Date Issued: 2021-04
An investigation of alternative separation strategies for common chemical mixtures by means of host-guest chemistry protocols with host compounds N,N′- bis(5-phenyl-5-dibenzo[a,d]cycloheptenyl)ethylenediamine and N,N’-bis(5-phenyl-10,11- dihydro-5-dibenzo[a,d]cycloheptenyl)ethylenediamine
- Authors: Barton, Danica Brione
- Date: 2023-04
- Subjects: Ethylenediaminetetraacetic acid -- South Africa , Enzymes –Analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61176 , vital:69791
- Description: In this work, the selectivity behaviour of two host compounds, namely N,N’-bis(5-phenyl-5- ibenzo[a,d]cycloheptenyl)ethylenediamine (H1) and N,N’-bis(5-phenyl-10,11-dihydro-5- ibenzo[a,d]cycloheptenyl)ethylenediamine (H2), was assessed in mixtures of difficult-toseparate compounds, including the xylenes and ethylbenzene, pyridine and methylpyridines, and anisole and methylanisoles. These host compounds were synthesized using Grignard addition reactions with phenylmagnesium bromide on dibenzo[a,d]cyclohepten-5-one and 10,11- dihydrodibenzo[a,d]cyclohepten-5-one, respectively. The resultant alcohols were treated with perchloric acid to form the corresponding perchlorate salts, which were then reacted with ethylenediamine to afford the required H1 and H2 host compounds. Yields were 95 ad 52% for this final step in each case. An investigation of the conformations, both from experiment (using single crystal X-ray diffractometry (SCXRD) on the apohost compound) and computational calculations was undertaken. Unfortunately, H1 always crystallized out as a powder unless this host compound formed a complex with a guest species, and so could not be subjected to SCXRD analysis as apohost alone. However, a single crystal structure for apohost H2 was successfully obtained and compared with computational data from a previous investigation. It was observed that the conformation of apohost H2 compared favourably with that of the lowest energy conformer from that work. In single solvent recrystallization experiments with o-, m-, p-xylene (o-Xy, m-Xy, p-Xy) and ethylbenzene (EB), both H1 and H2 formed complexes with only one of the four guest species, namely p-Xy and o-Xy, respectively. The host:guest (H:G) ratios were 1:1 for both of these complexes. In the equimolar guest/guest competition experiments, inclusion complexes only formed when p-Xy or o-Xy, respectively, were present in the mixtures; if p-Xy (for experiments with H1) or o-Xy (H2) was absent from these mixtures, only apohost was recovered from the glass vessels. Three selectivity profiles were constructed for each of these host compounds, in which each one was recrystallized from binary mixed guests in various proportions. These demonstrated an overwhelming preference of H1 for p-Xy and H2 for o-Xy, which concurred with the results from the equimolar experiments. Thermal analysis using H1∙p-Xy revealed that this complex was unstable at ambient conditions, while SCXRD explained this observation: this complex may be defined as a true clathrate since no host‧‧‧guest interactions were identified at all, and the guest was retained in the complex by means of steric factors alone. Furthermore, the guest molecules resided in wide open channels that may have facilitated the guest release process. H2∙o-Xy, on the other hand, was stable at room temperature, and the guest release event only commenced at 69.7 °C (Ton). This too was explained by SCXRD analyses in that interactions between host and guest species were observed in this case. Additionally, the guest molecules were housed in discrete cages, which made their escape more challenging compared with p-Xy in H1∙p-Xy. It was concluded that, in this guest series, both of the host compounds would be effective as separatory tools employing host-guest chemistry protocols due to their remarkable selectivities for p-Xy (H1) and o-Xy (H2). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
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- Date Issued: 2023-04
Antifungal activity of silver nanoparticles on Cryptococcus species
- Authors: Roman, Nasstasja
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Cryptococcus
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52089 , vital:43445
- Description: Cryptococcus neoformans is responsible for cryptococcal infections, which have become a great concern particularly in immunocompromised patients. This pulmonary disease causes damage to lung tissue and is presumed to be responsible for approximately 650,000 deaths annually. There is a major need for novel antimicrobial agents to avoid the emergence of resistant strains due to extended use of known antifungal drugs. Silver has become an important antimicrobial agent used in medical devices, cosmetics and even house-hold or clothing products. It is highly toxic and has a reduced risk of resistance. Silver nanoparticles have been broadly explored as an antimicrobial agent due to its high reactivity, large surface area and small size. They have been reported to display antimicrobial activity towards bacteria, viruses and fungi. C. neoformans is a pathogenic microorganism that possesses a number of virulence factors which increases the infectivity of the microorganism in immunocompromised individuals. Some of these include the presence of a polysaccharide capsule, melanin, urease and phospholipase production. Owing to limited availability of antifungal drugs and the possibility of drug resistance, this study focused on an alternative antimicrobial agent, namely silver nanoparticles, and the effects that silver nanoparticles had on fungal β-glucan, chitin and urease, phospholipase and melanin virulence factors. Results from our study show that silver nanoparticles inhibited the growth of C. neoformans at concentrations between 3.125 ƒM and 25 ƒM. Both 26.4 nm and 28.4 nm nanoparticles displayed growth inhibition, but were unable to kill the organism at concentrations of 200 ƒM and above. The silver nanoparticles caused a reduction in βglucan content. There was also an accumulation of intracellular ROS, and phospholipase activity, was reduced. In contrast, the organism displayed an increase in chitin content, melanin and urease activity upon exposure to the nanoparticles. This study shows that chemically synthesized silver nanoparticles are an effective antifungal alternative that greatly reduces or inhibits C. neoformans growth at very low concentrations (ƒM). For future studies it may be feasible to investigate the use of these nanoparticles in combination with known antifungal agents, to prevent the emergence of resistance and inhibit possible defense mechanisms displayed by the organism. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
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- Date Issued: 2021-04