An investigation of the morphological and electrochemical properties of anode titanate materials used in li-ion batteries
- Authors: Gelant, Charmaine
- Date: 2020
- Subjects: Electrodes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48346 , vital:40851
- Description: The chemistry involved in the synthesis of lithium titanium oxide (Li4Ti5O12) for lithium ion battery applications is critical for understanding and optimizing the most cost-efficient manufacturing route. This study investigates the sol-gel synthesis technique of Li4Ti5O12 using triethanolamine (TEOA) as complexing agent by means of in-situ Powder X-ray Diffraction (PXRD). The influence of doping with various metals such as Al3+, Mg2+ , Co3+ and Ni2+ that were made as precursors was considered for comparison purposes due to literature showing improved electrochemical performance using the molecular formula of Li4Ti4.95M0.05O12. The in-situ PXRD technique was used to identify the phase changes that occurred in the thermal synthesis process from the sol-gel precursors to the final crystalline oxides. The materials’ decomposition mechanisms were characterized by thermal gravimetric analysis (TGA) as the precursors were gradually heated to obtain the final oxides. BET surface area analysis and scanning electron microscopy (SEM) were used in order to obtain a morphological understanding of the materials during the synthetic route at specific temperature regions. The in-situ studies have shown that the precursor materials are amorphous at room temperature to about 550 °C, after which the spinel and anatase formed, with relatively small crystallites and a large surface area. The study also showed that a crystalline intermediate phase formed at around 150-200 °C, which then disappeared above 250 °C and was speculated to be a titanium acid (H2Ti2O5.H2O). Upon further heating above 250 °C, the anatase phase converted to the high temperature stable TiO2 phase, rutile, also with an increased formation of the expected LTO spinel phase around 850 °C. Keeping the material at 850 °C, isothermally, did show further conversion of the rutile into the desired spinel phase Li4Ti5O12 (LTO) with an increase in the crystallite size and a decrease in surface area. SEM analysis of the material at 850 °C did show some extensive sintering of the particles with some samples indicating the presence of an additional β-Li2TiO3 phase that formed at the high temperatures. Upon cooling, the βLi2TiO3 phase showed a distinctive powder diffraction pattern besides the typical spinel II LTO phase. The study showed that in comparison to the oxide formed at 850 °C, a mixed phase material of the spinel LTO, anatase and rutile could be achieved at temperatures close to 650 °C with very small crystallites and a relatively large surface area that showed desirable electrochemical properties. Suitable Li-ion coin cells were built with the undoped spinel and doped materials that were isothermally made at 650 °C and 850 °C, whereby their electrochemical properties were tested in the form of cell capacity, electrochemical impedance spectroscopy (EIS) and differential capacity (dQ/dV) studies. The cells made with the materials at 850 °C provided reasonable capacity where the dQ/dV plots did show a single step redox reaction at around 1.5V vs Li/Li+ . These were compared to cells made with commercially available LTO and highlighted the importance of high surface area and small particle size of the active material in order to achieve acceptable electrochemical performances. The cells with the materials made at 650 °C showed to have good capacity upon the first discharge with a number of irreversible phase transitions that were subsequently not observed upon recharging. The dQ/dV graphs showed that the phase transitions were unique to the mixed phase composition of the material made at low temperatures and the cells made with the doped spinel materials were on average better performing than the undoped LTO material. Subsequent grinding steps of the active material made at 850 °C improved the capacity performance of the cells but were still lower when compared to the commercially available material. Hence, significantly longer grinding and processing time would be required to achieve battery active materials that are acceptable for commercial use. This study highlights the importance of understanding the phase transitions that occur during the synthesis route of making battery active material, where doping with different elements and using lower temperatures during synthesis could lead to electroactive materials that do not require additional excessive processing steps such as grinding.
- Full Text:
- Date Issued: 2020
- Authors: Gelant, Charmaine
- Date: 2020
- Subjects: Electrodes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48346 , vital:40851
- Description: The chemistry involved in the synthesis of lithium titanium oxide (Li4Ti5O12) for lithium ion battery applications is critical for understanding and optimizing the most cost-efficient manufacturing route. This study investigates the sol-gel synthesis technique of Li4Ti5O12 using triethanolamine (TEOA) as complexing agent by means of in-situ Powder X-ray Diffraction (PXRD). The influence of doping with various metals such as Al3+, Mg2+ , Co3+ and Ni2+ that were made as precursors was considered for comparison purposes due to literature showing improved electrochemical performance using the molecular formula of Li4Ti4.95M0.05O12. The in-situ PXRD technique was used to identify the phase changes that occurred in the thermal synthesis process from the sol-gel precursors to the final crystalline oxides. The materials’ decomposition mechanisms were characterized by thermal gravimetric analysis (TGA) as the precursors were gradually heated to obtain the final oxides. BET surface area analysis and scanning electron microscopy (SEM) were used in order to obtain a morphological understanding of the materials during the synthetic route at specific temperature regions. The in-situ studies have shown that the precursor materials are amorphous at room temperature to about 550 °C, after which the spinel and anatase formed, with relatively small crystallites and a large surface area. The study also showed that a crystalline intermediate phase formed at around 150-200 °C, which then disappeared above 250 °C and was speculated to be a titanium acid (H2Ti2O5.H2O). Upon further heating above 250 °C, the anatase phase converted to the high temperature stable TiO2 phase, rutile, also with an increased formation of the expected LTO spinel phase around 850 °C. Keeping the material at 850 °C, isothermally, did show further conversion of the rutile into the desired spinel phase Li4Ti5O12 (LTO) with an increase in the crystallite size and a decrease in surface area. SEM analysis of the material at 850 °C did show some extensive sintering of the particles with some samples indicating the presence of an additional β-Li2TiO3 phase that formed at the high temperatures. Upon cooling, the βLi2TiO3 phase showed a distinctive powder diffraction pattern besides the typical spinel II LTO phase. The study showed that in comparison to the oxide formed at 850 °C, a mixed phase material of the spinel LTO, anatase and rutile could be achieved at temperatures close to 650 °C with very small crystallites and a relatively large surface area that showed desirable electrochemical properties. Suitable Li-ion coin cells were built with the undoped spinel and doped materials that were isothermally made at 650 °C and 850 °C, whereby their electrochemical properties were tested in the form of cell capacity, electrochemical impedance spectroscopy (EIS) and differential capacity (dQ/dV) studies. The cells made with the materials at 850 °C provided reasonable capacity where the dQ/dV plots did show a single step redox reaction at around 1.5V vs Li/Li+ . These were compared to cells made with commercially available LTO and highlighted the importance of high surface area and small particle size of the active material in order to achieve acceptable electrochemical performances. The cells with the materials made at 650 °C showed to have good capacity upon the first discharge with a number of irreversible phase transitions that were subsequently not observed upon recharging. The dQ/dV graphs showed that the phase transitions were unique to the mixed phase composition of the material made at low temperatures and the cells made with the doped spinel materials were on average better performing than the undoped LTO material. Subsequent grinding steps of the active material made at 850 °C improved the capacity performance of the cells but were still lower when compared to the commercially available material. Hence, significantly longer grinding and processing time would be required to achieve battery active materials that are acceptable for commercial use. This study highlights the importance of understanding the phase transitions that occur during the synthesis route of making battery active material, where doping with different elements and using lower temperatures during synthesis could lead to electroactive materials that do not require additional excessive processing steps such as grinding.
- Full Text:
- Date Issued: 2020
An IT Risk Management Framework for provincial business entities : a case study for Limpopo Economic Development Agency, Limpopo Province, South Africa
- Authors: Mabitsela, Ngoakoana Unity
- Date: 2020
- Subjects: Risk management -- South Africa -- Limpopo Business enterprises -- Computer networks -- Security measures -- South Africa -- Limpopo , Information technology -- Security measures -- South Africa -- Limpopo
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/49463 , vital:41723
- Description: This study focused on a lack of an Information Technology Risk Management (ITRM) framework tailored for provincial business entities to assist with the management of IT risks. The research was aimed at developing a tailored IT risk management framework that would assist provincial business entities with an effective ITRM process. This was achieved through identifying factors that constitute an ITRM framework, determining the current IT risk management methods used in provincial business entities and assessing the IT risk culture. This research study was conducted at the Limpopo Economic Development Agency (LEDA), which is a provincial business entity in the Limpopo province. The objectives of the study were accomplished using a design science research approach which involved the creation of an artefact and design theory as a means to improve the current state of practice as well as existing research knowledge about provincial business entities and their management of IT risks. The Nelson Mandela University Design Science Methodology Framework (NMU-DSFM) was identified as the methodology to be followed to devise the contribution in the form of an artefact. It was found that the organisation does not have a positive IT risk culture. From the study of the data analysis performed, it was evident that provincial business entities have challenges associated with adequately identifying IT risks. The findings highlighted that for the proper management of risks, risk governance should be effective by ensuring that the board of directors takes the responsibility of IT risk management, and the essentials of risk governance were discussed at length. The research output for this study was a framework. The adoption of this framework may positively contribute to strengthening governance of IT risk management in the provincial business entities. Best practices were highlighted for ease of reference to determine what is required and how to implement this regarding IT risk management.
- Full Text:
- Date Issued: 2020
- Authors: Mabitsela, Ngoakoana Unity
- Date: 2020
- Subjects: Risk management -- South Africa -- Limpopo Business enterprises -- Computer networks -- Security measures -- South Africa -- Limpopo , Information technology -- Security measures -- South Africa -- Limpopo
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/49463 , vital:41723
- Description: This study focused on a lack of an Information Technology Risk Management (ITRM) framework tailored for provincial business entities to assist with the management of IT risks. The research was aimed at developing a tailored IT risk management framework that would assist provincial business entities with an effective ITRM process. This was achieved through identifying factors that constitute an ITRM framework, determining the current IT risk management methods used in provincial business entities and assessing the IT risk culture. This research study was conducted at the Limpopo Economic Development Agency (LEDA), which is a provincial business entity in the Limpopo province. The objectives of the study were accomplished using a design science research approach which involved the creation of an artefact and design theory as a means to improve the current state of practice as well as existing research knowledge about provincial business entities and their management of IT risks. The Nelson Mandela University Design Science Methodology Framework (NMU-DSFM) was identified as the methodology to be followed to devise the contribution in the form of an artefact. It was found that the organisation does not have a positive IT risk culture. From the study of the data analysis performed, it was evident that provincial business entities have challenges associated with adequately identifying IT risks. The findings highlighted that for the proper management of risks, risk governance should be effective by ensuring that the board of directors takes the responsibility of IT risk management, and the essentials of risk governance were discussed at length. The research output for this study was a framework. The adoption of this framework may positively contribute to strengthening governance of IT risk management in the provincial business entities. Best practices were highlighted for ease of reference to determine what is required and how to implement this regarding IT risk management.
- Full Text:
- Date Issued: 2020
An unsung dialogue: music, society and the history of The Flames
- Authors: Park, Duncan Keith
- Date: 2020
- Subjects: The Flames (Musical group) , Fataar, Steve , Durban (South Africa) -- History , Durban (South Africa) -- Race relations , Musical groups -- South Africa , Music -- Social aspects -- South Africa , Music -- Social aspects -- South Africa -- Durban , South Africa -- Politics and government -- 1961-1978
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/169632 , vital:41780
- 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. South Africa during apartheid, with its racialised legislation provides an ideal context to scrutinize the effects (both potential and real) of music on social conditions. The Flames provide a particularly relevant case point; being a collective of “mixed-race” individuals classified as Coloured performing for a multi-racial fan- base. This means that at their concerts, audience members would have frequently been from a variety of different racial backgrounds. This would have been in direct contravention to the National Party‟s (NP) Separate Amenities Act as well as the policy of “separate development”, the cornerstone of apartheid. The thesis will firstly contextualise the research within the broader, global historical context, as well as in the existing theoretical literature which focuses on the relationship between music, politics and society. Firstly, this will entail a brief historical account of popular music around the world during the twentieth century. Through this we will observe both the ways in which the development and popularisation of various forms of popular music came to be shaped in a particular way, as well as the ways in which the public received this music. This will include an examination of positive responses to certain kinds of popular music which resonated and became popular with various sectors of society. Conversely, it will also closely examine the backlashes against these musical forms, and attempt to identify why certain sectors of the public were deeply opposed to particular kinds of popular music which may have been perceived to embody certain values and meanings. This will be conducted by studying various forms of popular music from the turn of the twentieth century into the early 1970s with a cross-cultural, global perspective, examining particular historical instances and existing theories relating to these instances. Chapter one will then shift from a global perspective and will situate the research within the South African musical context specifically. This will include an account of the development of South African popular music through the twentieth century in relation to the country's politics. Through examining this relationship, the dialogue between historical case studies and theoretical literature will continue, in which existing theories relating to the relationship between music, politics and society will be discussed. This theoretical literature will be made use of in the final section of the paper in order to make sense of The Flames and their role in South African history. The second section of this thesis will focus on the socio-historical context of the city of Durban under apartheid. The author will contextualise the research through a narrative historical retelling of Durban‟s social history, focusing on both political and social public mobilisation and the role of cultural spaces and practices within these his torical moments and their relevant structures. Attention will be paid to the development of segregation and apartheid within Durban specifically, while racial relations will also be fo cused upon. This will provide the reader with the necessary background required in order to meaningfully understand how the band The Flames came into existence, became popular, and whether or not they had any meaningful effect on their historical context. The section on Durban's history will be followed by a brief account of Durban's Coloured community's history, as well as a discussion around Coloured identity more broadly within the South African context. This will be vital to the research due to the fact that the musicians of The Flames were classified as Coloured under apartheid, and such an historical background will be critical to understanding the social, political and economic context of the band. Finally, the thesis will end with the written history of The Flame . This final section will provide an account of The Flames' history in which the band will be made sense of within the context of Durban during apartheid, as well as within the context of South African music, and the globalised context of popular music. By situating the band within these three contexts, we can truly assess both how they were shaped by their contexts, and whether they had any effect on these contexts of which they were a part. In this section those existing theories around the relationship between music, politics and society will be discussed and assessed in order to determine how useful a framework they may be for understanding popular music in certain historical contexts. In this way, the research aims to make a meaningful contribution to the study of music and its socio-political role throughout history, as well as to the broader understanding of Durban's history. Specifically, the role of music in Durban's history is being examined, and the researcher hopes that this work can begin to open up new discussions around the importance of studying music in Durban, and South Africa's history. Additionally, this thesis will open up a new area of research into a band which, until this point, has not been engaged with in the field of music history whatsoever. .
- Full Text:
- Date Issued: 2020
- Authors: Park, Duncan Keith
- Date: 2020
- Subjects: The Flames (Musical group) , Fataar, Steve , Durban (South Africa) -- History , Durban (South Africa) -- Race relations , Musical groups -- South Africa , Music -- Social aspects -- South Africa , Music -- Social aspects -- South Africa -- Durban , South Africa -- Politics and government -- 1961-1978
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/169632 , vital:41780
- 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. South Africa during apartheid, with its racialised legislation provides an ideal context to scrutinize the effects (both potential and real) of music on social conditions. The Flames provide a particularly relevant case point; being a collective of “mixed-race” individuals classified as Coloured performing for a multi-racial fan- base. This means that at their concerts, audience members would have frequently been from a variety of different racial backgrounds. This would have been in direct contravention to the National Party‟s (NP) Separate Amenities Act as well as the policy of “separate development”, the cornerstone of apartheid. The thesis will firstly contextualise the research within the broader, global historical context, as well as in the existing theoretical literature which focuses on the relationship between music, politics and society. Firstly, this will entail a brief historical account of popular music around the world during the twentieth century. Through this we will observe both the ways in which the development and popularisation of various forms of popular music came to be shaped in a particular way, as well as the ways in which the public received this music. This will include an examination of positive responses to certain kinds of popular music which resonated and became popular with various sectors of society. Conversely, it will also closely examine the backlashes against these musical forms, and attempt to identify why certain sectors of the public were deeply opposed to particular kinds of popular music which may have been perceived to embody certain values and meanings. This will be conducted by studying various forms of popular music from the turn of the twentieth century into the early 1970s with a cross-cultural, global perspective, examining particular historical instances and existing theories relating to these instances. Chapter one will then shift from a global perspective and will situate the research within the South African musical context specifically. This will include an account of the development of South African popular music through the twentieth century in relation to the country's politics. Through examining this relationship, the dialogue between historical case studies and theoretical literature will continue, in which existing theories relating to the relationship between music, politics and society will be discussed. This theoretical literature will be made use of in the final section of the paper in order to make sense of The Flames and their role in South African history. The second section of this thesis will focus on the socio-historical context of the city of Durban under apartheid. The author will contextualise the research through a narrative historical retelling of Durban‟s social history, focusing on both political and social public mobilisation and the role of cultural spaces and practices within these his torical moments and their relevant structures. Attention will be paid to the development of segregation and apartheid within Durban specifically, while racial relations will also be fo cused upon. This will provide the reader with the necessary background required in order to meaningfully understand how the band The Flames came into existence, became popular, and whether or not they had any meaningful effect on their historical context. The section on Durban's history will be followed by a brief account of Durban's Coloured community's history, as well as a discussion around Coloured identity more broadly within the South African context. This will be vital to the research due to the fact that the musicians of The Flames were classified as Coloured under apartheid, and such an historical background will be critical to understanding the social, political and economic context of the band. Finally, the thesis will end with the written history of The Flame . This final section will provide an account of The Flames' history in which the band will be made sense of within the context of Durban during apartheid, as well as within the context of South African music, and the globalised context of popular music. By situating the band within these three contexts, we can truly assess both how they were shaped by their contexts, and whether they had any effect on these contexts of which they were a part. In this section those existing theories around the relationship between music, politics and society will be discussed and assessed in order to determine how useful a framework they may be for understanding popular music in certain historical contexts. In this way, the research aims to make a meaningful contribution to the study of music and its socio-political role throughout history, as well as to the broader understanding of Durban's history. Specifically, the role of music in Durban's history is being examined, and the researcher hopes that this work can begin to open up new discussions around the importance of studying music in Durban, and South Africa's history. Additionally, this thesis will open up a new area of research into a band which, until this point, has not been engaged with in the field of music history whatsoever. .
- Full Text:
- Date Issued: 2020
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
Analysis of maximum power point tracking data for obtaining photovoltaic parameters
- Authors: Chitura, Anesu Godfrey
- Date: 2020
- Subjects: Photovoltaic power system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18576 , vital:42610
- Description: As a standard, photovoltaic (PV) modules are rated by the use of standard test conditions (STC). Such details entail current and voltage (I-V) measurements for modules under an irradiance of 1000 W/m2 an air mass ration of 1.5 global spectrum and 25˚C cell temperature. Outdoor weather conditions continuously vary with time and from one location to the other. This further offset the expected operational power outputs as outdoor conditions are generally characterized by high cell temperatures. The technology one uses will also complicate the power output prediction since different module technologies respond to these outdoor conditions differently. I-V tracers are able to measure the full I-V curve of the module thus can give the operational PV parameters at any given time. However, these tracers are sold at exorbitant prices and they require skilled personnel in order to operate them. Most if not all tracers require isolation of the module under test thereby disrupting the power production function of the module._________________________________________________________________________________________________________________________________________ In this study a method to obtain photovoltaic (PV) parameters using the maximum power point tracking (MPPT) data is presented and tested under natural outdoor conditions. The method features a customized data acquisition system (DAS) designed for the measurement and storage of meteorological and MPPT data. The DAS is capable of extracting parameters from any combination of modules with an open circuit voltage 〖(V〗_oc) less than or equal to 120 Volts and a short circuit current 〖(I〗_sc) of 100 Amps. The system used is capable of extracting MPPT data using a reliable, improved storage and a programmable data logger. In order to match the sampling operational speeds of internal charge controller switches a computer interfaced Peripheral Component Interconnect (PCI) card was also used. Data collection and characterization of the MPPT data was done in such a way that the power generation process remained uninterrupted throughout the whole process. The regression nonlinear least squares method was used to fit MPPT crests and obtain the knee part of the I-V curve. This was then extrapolated to obtain the full I-V curve, which then produces the operational PV parameters. The resultant parameters from the characterization process were logged and accessible at any time. The end result was a method that can be incorporated within a charge controller for quick, hands-free PV parameter extraction, using only the MPPT scanned data.
- Full Text:
- Date Issued: 2020
- Authors: Chitura, Anesu Godfrey
- Date: 2020
- Subjects: Photovoltaic power system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18576 , vital:42610
- Description: As a standard, photovoltaic (PV) modules are rated by the use of standard test conditions (STC). Such details entail current and voltage (I-V) measurements for modules under an irradiance of 1000 W/m2 an air mass ration of 1.5 global spectrum and 25˚C cell temperature. Outdoor weather conditions continuously vary with time and from one location to the other. This further offset the expected operational power outputs as outdoor conditions are generally characterized by high cell temperatures. The technology one uses will also complicate the power output prediction since different module technologies respond to these outdoor conditions differently. I-V tracers are able to measure the full I-V curve of the module thus can give the operational PV parameters at any given time. However, these tracers are sold at exorbitant prices and they require skilled personnel in order to operate them. Most if not all tracers require isolation of the module under test thereby disrupting the power production function of the module._________________________________________________________________________________________________________________________________________ In this study a method to obtain photovoltaic (PV) parameters using the maximum power point tracking (MPPT) data is presented and tested under natural outdoor conditions. The method features a customized data acquisition system (DAS) designed for the measurement and storage of meteorological and MPPT data. The DAS is capable of extracting parameters from any combination of modules with an open circuit voltage 〖(V〗_oc) less than or equal to 120 Volts and a short circuit current 〖(I〗_sc) of 100 Amps. The system used is capable of extracting MPPT data using a reliable, improved storage and a programmable data logger. In order to match the sampling operational speeds of internal charge controller switches a computer interfaced Peripheral Component Interconnect (PCI) card was also used. Data collection and characterization of the MPPT data was done in such a way that the power generation process remained uninterrupted throughout the whole process. The regression nonlinear least squares method was used to fit MPPT crests and obtain the knee part of the I-V curve. This was then extrapolated to obtain the full I-V curve, which then produces the operational PV parameters. The resultant parameters from the characterization process were logged and accessible at any time. The end result was a method that can be incorporated within a charge controller for quick, hands-free PV parameter extraction, using only the MPPT scanned data.
- Full Text:
- Date Issued: 2020
Analysis of the contribution of socio-economic factors on poor academic performance of grade 12 learners: the case of Butterworth education district, Eastern Cape Province South Africa
- Authors: Lubisi, Anathi
- Date: 2020
- Subjects: Performance standards -- South Africa Teacher effectiveness -- South Africa
- Language: English
- Type: Thesis , Masters , MSoc (Sociology)
- Identifier: http://hdl.handle.net/10353/18141 , vital:42236
- Description: The drive of this research project was to discover factors contributing to the poor academic performance of Grade 12 learners at two selected schools in the Butterworth Education District, Eastern Cape province South Africa. The participants were Grade 12 learners, Grade 12 teachers and parents of Grade 12 learners in both schools. Both schools are located in rural areas of Mnquma municipality under the Butterworth education district. The study used both qualitative and quantitative research methods. The motivation behind using triangulation was to decrease or offset the deficiency of a specific methodology and for deeper understanding of the discoveries of the study. Use of triangulation in this study was aimed at expanding the legitimacy, dependability and generalizability of the results of the study. The findings of the study revealed that the most determining factor that contributes to the poor academic performance of Grade 12 learners in the Butterworth Education District is the unavailability and inadequacy of instructional resources. This is the most critical school resource which the parents cannot afford to buy for their children. Both teachers and Grade 12 learners indicated that they do not have a school library or a community library. The majority of learners also indicated that they do not have enough textbooks in all subjects and their parents concurred that their children end up sharing textbooks with their peers. Furthermore, the three groups of participants agreed that learners do not have access to computers, and the school does not have a science lab for Grade 12 learners doing science. The core argument of this study is that a poor socio-economic background is a primary contributor to low academic performance of Grade 12 learners at the Butterworth Education District. The findings of this study support this thesis as they indicate that instructional resources are inadequate, a school or community library is vii non-existent, and there is not enough textbooks at the selected schools. With parents from low socio-economic background, the Butterworth community is also not in a position to supplement these insufficient instructional resources. This study utilized the cultural reproduction theory of Bourdieu (1977) to explore a system of education in industrialized communities and the way it works to illuminate class differences in academic performance and achievement of Grade 12 learners. The study made recommendations that should be put in place to improve the academic performance of Grade 12 learners in the Butterworth Education District. The most important of these recommendations is that government officials should provide educational resources (teaching and learning resources). Furthermore, the researcher suggest that for further research, it would be interesting to find out about learners that perform well, regardless of identified factors that cause other learners to perform poorly to help them improve their academic performance.
- Full Text:
- Date Issued: 2020
- Authors: Lubisi, Anathi
- Date: 2020
- Subjects: Performance standards -- South Africa Teacher effectiveness -- South Africa
- Language: English
- Type: Thesis , Masters , MSoc (Sociology)
- Identifier: http://hdl.handle.net/10353/18141 , vital:42236
- Description: The drive of this research project was to discover factors contributing to the poor academic performance of Grade 12 learners at two selected schools in the Butterworth Education District, Eastern Cape province South Africa. The participants were Grade 12 learners, Grade 12 teachers and parents of Grade 12 learners in both schools. Both schools are located in rural areas of Mnquma municipality under the Butterworth education district. The study used both qualitative and quantitative research methods. The motivation behind using triangulation was to decrease or offset the deficiency of a specific methodology and for deeper understanding of the discoveries of the study. Use of triangulation in this study was aimed at expanding the legitimacy, dependability and generalizability of the results of the study. The findings of the study revealed that the most determining factor that contributes to the poor academic performance of Grade 12 learners in the Butterworth Education District is the unavailability and inadequacy of instructional resources. This is the most critical school resource which the parents cannot afford to buy for their children. Both teachers and Grade 12 learners indicated that they do not have a school library or a community library. The majority of learners also indicated that they do not have enough textbooks in all subjects and their parents concurred that their children end up sharing textbooks with their peers. Furthermore, the three groups of participants agreed that learners do not have access to computers, and the school does not have a science lab for Grade 12 learners doing science. The core argument of this study is that a poor socio-economic background is a primary contributor to low academic performance of Grade 12 learners at the Butterworth Education District. The findings of this study support this thesis as they indicate that instructional resources are inadequate, a school or community library is vii non-existent, and there is not enough textbooks at the selected schools. With parents from low socio-economic background, the Butterworth community is also not in a position to supplement these insufficient instructional resources. This study utilized the cultural reproduction theory of Bourdieu (1977) to explore a system of education in industrialized communities and the way it works to illuminate class differences in academic performance and achievement of Grade 12 learners. The study made recommendations that should be put in place to improve the academic performance of Grade 12 learners in the Butterworth Education District. The most important of these recommendations is that government officials should provide educational resources (teaching and learning resources). Furthermore, the researcher suggest that for further research, it would be interesting to find out about learners that perform well, regardless of identified factors that cause other learners to perform poorly to help them improve their academic performance.
- Full Text:
- Date Issued: 2020
Analysis of the effectiveness of Tulbaghia Violacea extracts as devulcanizing agents for synthetic CIS-1,4-polyisoprene vulcanizates
- Authors: Gxakuma, Lutho
- Date: 2020
- Subjects: Plant extracts , Plant products -- South Africa Medicinal plants -- South Africa Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49093 , vital:41600
- Description: Tulbaghia violacea is an indigenous plant commonly known as wild garlic, wilde knoffel in Afrikaans, isihaqa in Zulu or itswele lomlambo in Xhosa. Its leaves and bulbs are widely used as herbal remedies for various ailments and its medicinal uses include fever and colds, asthma, tuberculosis and stomach problems. Like all other members of the Alliacea family, Tulbaghia violacea produces a distinctive garlic-like odour when its leaves or rhizomes are damaged, resulting in the release of cysteine-derived sulphur compounds which include the oil-soluble organo-sulphur compounds and water-soluble cysteine derivatives. Chemically synthesized sulphur containing compounds have been reported to be effective devulcanizing agents and many industries prefer to perform devulcanization using them. Most commonly applied devulcanizing agents include disulphides, thiophenols and their zinc salts, and mercaptans which are mixed with the rubber scrap powder under specific reaction conditions. In this study, instead of performing devulcanization by using industrial synthesized sulphur containing compounds, the effectiveness of the extracts of organo-sulphur containing compounds from Tulbaghia violacea are evaluated as potential devulcanizing agents for synthetic cis-1,4-polyisoprene vulcanizates. This is a new, cheap and greener practice of rubber devulcanization. Diallyl disulphide, which is one of the organo-sulphur containing compounds present in Tulbaghia violacea, is the devulcanizing agent of interest to this study. The organo-sulphur containing compounds were extracted from the bulbs, roots and leaves of the plant using the soxhlet and ultrasonic bath extraction method. The solvent system used in the soxhlet extraction method was 2% of 2-propanol in n-hexane whereas in ultrasonic bath extraction method the solvent system used was 100% ethanol. An essential oil extract was obtained from the plant organs. The yield of the essential oil extracts obtained using the soxhlet extraction method was higher compared to the yield of the essential oil extracts obtained using the ultrasonic bath extraction method. According to the Fourier-Transform Infrared spectroscopy, the organo-sulphur containing compounds were present in the essential oil extracts of the plant. The essential oil extracts that were extracted using the soxhlet extraction method were chosen for further analysis. It was found out that the allyl sulphide and diallyl disulphide have the same retention time from the High Performance Liquid Chromatography (using a normal phase column). The Differential Scanning Calorimeter indicated that the allyl sulphide was not present in the essential oil extracts whereas the diallyl disulphide was present in the essential oil extract of the roots and leaves. The High Performance Liquid Chromatography was used to quantify the presence of the diallyl disulphide in the essential oil extract of roots and leaves. The quantity of diallyl disulphide was 23% in the dry mass of the essential oil extract of roots. In the essential oil extract of leaves the diallyl disulphide was very low concentrated and the High Performance Liquid Chromatography was less sensitive to detect it. According to the Thermogravimetric Analyser, it was found that the essential oil extracts begin to degrade at 120 °C and experience a multistage degradation. The softening temperature of the essential oil extracts was 60 °C from the Simultaneous Differential Scanning Calorimeter-Thermogravimetric Analyser. Conventional vulcanization of synthetic cis-1,4-polyisoprene was prepared with the vulcanization ingredients of zinc oxide, sulphur, stearic acid and N-tert-butyl-2-benzothiazole sulphenamide. The vulcanized synthetic cis-1,4-polyisoprene produced, under the heating temperature of 160 °C, was mixed with the essential oil extracts using the internal mixer at 60 °C and the two-roll mill. The overall torque, tan delta and the total crosslink density were the properties of interest of synthetic cis-1,4-polyisoprene vulcanizate in this study. The devulcanization temperature for the treated synthetic cis-1,4-polyisoprene vulcanizate with the essential oil extracts was optimized using the Dynamic Moving Die Rheometer and Dynamic Rubber Process Analyser. The amount of essential oil extracts at which they are effective devulcanizing agents for synthetic cis-1,4-polyisoprene vulcanizate was also optimized. During optimization a change on the latter mentioned properties of synthetic cis-1,4-polyisoprene vulcanizate was observed, indicating that the essential oil extracts have an effect as potential devulcanizing agents. The essential oil extracts increased the tan delta and reduced the overall torque, and total crosslink density of synthetic cis-1,4-polyisoprene vulcanizate as expected from devulcanizing agents. 200 °C was a preferable devulcanization temperature whereas essential oil extracts were effective as devulcanizing agent at 1.4%. However, the essential oil extracts influenced the overall torque and tan delta of synthetic cis-1,4-polyisoprene vulcanizate during the mixing process in the internal mixer at 60 °C, which was before heating at 200 °C. The essential oil extracts had a higher influence on the overall torque of synthetic cis-1,4-polyisoprene vulcanizate under heating at 200 °C whereas at 60 °C, during the mixing process, they had a higher influence on the tan delta of synthetic cis-1,4-polyisoprene vulcanizate. The essential oil extract of leaves had a higher influence on the overall torque whereas the essential oil extract of bulbs had a higher influence on the tan delta of synthetic cis-1,4-polyisoprene vulcanizate at 200 °C. The essential oil extract of roots shown a greater influence on the overall torque and tan delta of synthetic cis-1,4-polyisoprene vulcanizate at 60 °C during the mixing process. The effect of the essential oil extracts on the reversing heat capacity of synthetic cis-1,4-polyisoprene vulcanizate was also investigated using the Modulated Differential Scanning Calorimetry method. The essential oil extract of bulbs and roots influenced the reversing heat capacity of synthetic cis-1,4-polyisoprene vulcanizate by reducing it whereas the essential oil extract of leaves caused a temperature shift of the reversing heat capacity curve from the Modulated Differential Scanning Calorimeter thermogram of synthetic cis-1,4-polyisoprene vulcanizate. Therefore, the results indicated that the essential oil extracts of Tulbaghia violacea have an effect as an alternative potential devulcanizing agents for conventional vulcanized synthetic cis-1,4-polyisoprene whether the diallyl disulphide compound is present or not in them.
- Full Text:
- Date Issued: 2020
- Authors: Gxakuma, Lutho
- Date: 2020
- Subjects: Plant extracts , Plant products -- South Africa Medicinal plants -- South Africa Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49093 , vital:41600
- Description: Tulbaghia violacea is an indigenous plant commonly known as wild garlic, wilde knoffel in Afrikaans, isihaqa in Zulu or itswele lomlambo in Xhosa. Its leaves and bulbs are widely used as herbal remedies for various ailments and its medicinal uses include fever and colds, asthma, tuberculosis and stomach problems. Like all other members of the Alliacea family, Tulbaghia violacea produces a distinctive garlic-like odour when its leaves or rhizomes are damaged, resulting in the release of cysteine-derived sulphur compounds which include the oil-soluble organo-sulphur compounds and water-soluble cysteine derivatives. Chemically synthesized sulphur containing compounds have been reported to be effective devulcanizing agents and many industries prefer to perform devulcanization using them. Most commonly applied devulcanizing agents include disulphides, thiophenols and their zinc salts, and mercaptans which are mixed with the rubber scrap powder under specific reaction conditions. In this study, instead of performing devulcanization by using industrial synthesized sulphur containing compounds, the effectiveness of the extracts of organo-sulphur containing compounds from Tulbaghia violacea are evaluated as potential devulcanizing agents for synthetic cis-1,4-polyisoprene vulcanizates. This is a new, cheap and greener practice of rubber devulcanization. Diallyl disulphide, which is one of the organo-sulphur containing compounds present in Tulbaghia violacea, is the devulcanizing agent of interest to this study. The organo-sulphur containing compounds were extracted from the bulbs, roots and leaves of the plant using the soxhlet and ultrasonic bath extraction method. The solvent system used in the soxhlet extraction method was 2% of 2-propanol in n-hexane whereas in ultrasonic bath extraction method the solvent system used was 100% ethanol. An essential oil extract was obtained from the plant organs. The yield of the essential oil extracts obtained using the soxhlet extraction method was higher compared to the yield of the essential oil extracts obtained using the ultrasonic bath extraction method. According to the Fourier-Transform Infrared spectroscopy, the organo-sulphur containing compounds were present in the essential oil extracts of the plant. The essential oil extracts that were extracted using the soxhlet extraction method were chosen for further analysis. It was found out that the allyl sulphide and diallyl disulphide have the same retention time from the High Performance Liquid Chromatography (using a normal phase column). The Differential Scanning Calorimeter indicated that the allyl sulphide was not present in the essential oil extracts whereas the diallyl disulphide was present in the essential oil extract of the roots and leaves. The High Performance Liquid Chromatography was used to quantify the presence of the diallyl disulphide in the essential oil extract of roots and leaves. The quantity of diallyl disulphide was 23% in the dry mass of the essential oil extract of roots. In the essential oil extract of leaves the diallyl disulphide was very low concentrated and the High Performance Liquid Chromatography was less sensitive to detect it. According to the Thermogravimetric Analyser, it was found that the essential oil extracts begin to degrade at 120 °C and experience a multistage degradation. The softening temperature of the essential oil extracts was 60 °C from the Simultaneous Differential Scanning Calorimeter-Thermogravimetric Analyser. Conventional vulcanization of synthetic cis-1,4-polyisoprene was prepared with the vulcanization ingredients of zinc oxide, sulphur, stearic acid and N-tert-butyl-2-benzothiazole sulphenamide. The vulcanized synthetic cis-1,4-polyisoprene produced, under the heating temperature of 160 °C, was mixed with the essential oil extracts using the internal mixer at 60 °C and the two-roll mill. The overall torque, tan delta and the total crosslink density were the properties of interest of synthetic cis-1,4-polyisoprene vulcanizate in this study. The devulcanization temperature for the treated synthetic cis-1,4-polyisoprene vulcanizate with the essential oil extracts was optimized using the Dynamic Moving Die Rheometer and Dynamic Rubber Process Analyser. The amount of essential oil extracts at which they are effective devulcanizing agents for synthetic cis-1,4-polyisoprene vulcanizate was also optimized. During optimization a change on the latter mentioned properties of synthetic cis-1,4-polyisoprene vulcanizate was observed, indicating that the essential oil extracts have an effect as potential devulcanizing agents. The essential oil extracts increased the tan delta and reduced the overall torque, and total crosslink density of synthetic cis-1,4-polyisoprene vulcanizate as expected from devulcanizing agents. 200 °C was a preferable devulcanization temperature whereas essential oil extracts were effective as devulcanizing agent at 1.4%. However, the essential oil extracts influenced the overall torque and tan delta of synthetic cis-1,4-polyisoprene vulcanizate during the mixing process in the internal mixer at 60 °C, which was before heating at 200 °C. The essential oil extracts had a higher influence on the overall torque of synthetic cis-1,4-polyisoprene vulcanizate under heating at 200 °C whereas at 60 °C, during the mixing process, they had a higher influence on the tan delta of synthetic cis-1,4-polyisoprene vulcanizate. The essential oil extract of leaves had a higher influence on the overall torque whereas the essential oil extract of bulbs had a higher influence on the tan delta of synthetic cis-1,4-polyisoprene vulcanizate at 200 °C. The essential oil extract of roots shown a greater influence on the overall torque and tan delta of synthetic cis-1,4-polyisoprene vulcanizate at 60 °C during the mixing process. The effect of the essential oil extracts on the reversing heat capacity of synthetic cis-1,4-polyisoprene vulcanizate was also investigated using the Modulated Differential Scanning Calorimetry method. The essential oil extract of bulbs and roots influenced the reversing heat capacity of synthetic cis-1,4-polyisoprene vulcanizate by reducing it whereas the essential oil extract of leaves caused a temperature shift of the reversing heat capacity curve from the Modulated Differential Scanning Calorimeter thermogram of synthetic cis-1,4-polyisoprene vulcanizate. Therefore, the results indicated that the essential oil extracts of Tulbaghia violacea have an effect as an alternative potential devulcanizing agents for conventional vulcanized synthetic cis-1,4-polyisoprene whether the diallyl disulphide compound is present or not in them.
- Full Text:
- Date Issued: 2020
Analysis of the existence of the Phillips curve, Okun’s law and Taylor rule in the Zambian economy
- Authors: Chella, Siame Nampasa
- Date: 2020
- Subjects: Unemployment -- Effect of inflation -- Mathematical models --Zambia
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/49783 , vital:41800
- Description: The objective for this study was to explore the relationship between inflation and growth with an understanding of the effects of unemployment on growth. The primary objective of this paper was to investigate the existence of Phillips Curve, Okun’s Law, and Taylor Rule in Zambia on the basis that Zambia is a youthful economy, with a growing population, which is expected to temper with unemployment rates, as an increase in the supply of labour might be too high for the demand for jobs available. To be specific, the study aims at determining the relationship between inflation and growth and seeks to understand what policy measures have been undertaken to curb inflation and reduce unemployment in Zambia. To achieve this, a quantitative research was undertaken using the ARDL cointegration model in conjunction with sensitivity tests to cater for structural changes in the economy with 2007 standing as the break point, as well as paying attention to the fact that different policy regimes employed during the course of the data covered, that being, 1996 to 2017, would affect that rates of unemployment, inflation and growth of the country, across period under review. The study revealed that Zambia faces a Hybrid New Keynesian Phillips Curve during the period under study which is dominated by a mixture of both back-ward and forward-looking aspects of inflation. This specifically, paints the effects of inflation persistence as well future expectations of inflation on growth. Further, a cointegration relationship was established between unemployment and output, while Taylor principles were found not to apply to the Zambian economy, which have proved in other economies to be foundation blocks for good economic growth and as such significant to both fiscal and monetary policy authorities of the economy. The researcher therefore recommends that Zambian policy makers, that is, both the fiscal and the monetary authorities, work together in order to attain minimal and optimal levels of inflation to help achieve a conducive economic environment for the country.
- Full Text:
- Date Issued: 2020
- Authors: Chella, Siame Nampasa
- Date: 2020
- Subjects: Unemployment -- Effect of inflation -- Mathematical models --Zambia
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/49783 , vital:41800
- Description: The objective for this study was to explore the relationship between inflation and growth with an understanding of the effects of unemployment on growth. The primary objective of this paper was to investigate the existence of Phillips Curve, Okun’s Law, and Taylor Rule in Zambia on the basis that Zambia is a youthful economy, with a growing population, which is expected to temper with unemployment rates, as an increase in the supply of labour might be too high for the demand for jobs available. To be specific, the study aims at determining the relationship between inflation and growth and seeks to understand what policy measures have been undertaken to curb inflation and reduce unemployment in Zambia. To achieve this, a quantitative research was undertaken using the ARDL cointegration model in conjunction with sensitivity tests to cater for structural changes in the economy with 2007 standing as the break point, as well as paying attention to the fact that different policy regimes employed during the course of the data covered, that being, 1996 to 2017, would affect that rates of unemployment, inflation and growth of the country, across period under review. The study revealed that Zambia faces a Hybrid New Keynesian Phillips Curve during the period under study which is dominated by a mixture of both back-ward and forward-looking aspects of inflation. This specifically, paints the effects of inflation persistence as well future expectations of inflation on growth. Further, a cointegration relationship was established between unemployment and output, while Taylor principles were found not to apply to the Zambian economy, which have proved in other economies to be foundation blocks for good economic growth and as such significant to both fiscal and monetary policy authorities of the economy. The researcher therefore recommends that Zambian policy makers, that is, both the fiscal and the monetary authorities, work together in order to attain minimal and optimal levels of inflation to help achieve a conducive economic environment for the country.
- Full Text:
- Date Issued: 2020
Analysis of the regulation of HSP90α expression upon differentiation of C2C12 cells
- Authors: Holm, Nathan Christopher
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163318 , vital:41028
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Holm, Nathan Christopher
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163318 , vital:41028
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
Analysis of the relationship between changes in macroeconomic variables and various sector price indices of JSE
- Mapanda, Tungamirai Chisvuvo
- Authors: Mapanda, Tungamirai Chisvuvo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stock price indexes -- South Africa , Interest rates -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/147445 , vital:38637
- Description: Purpose- The purpose of this paper is to analyse the relationship between changes in domestic macroeconomic variables and various indices of the JSE during the full time period, June 1995 to December 2018 and the sub-periods, June 1995 to June 2007 and July 2007 to December 2018. Design/ methodology/ approach- The paper employs the Autoregressive Distributed Lag (ARDL) model approach to cointegration using monthly data from June 1995 to December 2018. Findings- In terms of the long run, the results show that the coincident indicator measure of domestic economic activity is positively and significantly related to the various JSE indices for all study periods. In terms of inflation, the results show no relationship between inflation rate and the various indices for both whole period and June 1995 to June 2007 sub period. However for the July 2007 to December 2018 sub period, JSE All Share Index and JSE Top 40 Index are negatively related. For the real effective exchange rate, only the Consumer Services Index is positively related to the exchange rate in terms of June 1995 to June 2007 sub period. However, JSE All Share Index and JSE Top 40 Index are negatively related to the exchange rate in all study periods. In terms of the short term interest rate, for the whole period, JSE All Share Index, JSE Top 40 Index, Health Care Index and Telecommunications Index are negatively related to interest rate. In terms of the June 1995 to June 2007 sub period, JSE All Share Index and Industrials Index are negatively related to the short term interest rate. For the July 2007 to December 2018 sub period, Telecommunications Index and Technology Index are negatively related. In terms of the short run, the coincident indicator is positively and significantly related to the various JSE indices for all study periods. Inflation is not significantly related to any index in the whole period. In terms of the June 1995 to June 2007 sub period, Industrials Index and Financials Index are positively related to inflation and in the July 2007 to December 2018 sub period, Consumer Goods Index, Health Index and Consumer Services Index are negatively related to the inflation rate. The real effective exchange rate is positively and significantly related to the various JSE indices in the different study periods. In terms of the short term interest rate, for the whole period and the June 1995 to June 2007 sub period only the Technology Index is not significantly and negatively related to the short term interest rate, but for the July 2007 to December 2018 sub period, Top 40 Index, Telecommunications Index and Technology Index are positively related to the interest rate. Only the Financial Index is negatively related to short term interest rates during this sub period. Research Limitations- Not a lot literature was found on the relationship between macroeconomic variables and the various sector indices of the JSE. Most previous work, in the South African context focused just on the JSE All Share Index. Practical Implications- The findings can help investors diversify their portfolios into indices that benefit from expected changes in macroeconomic variables, such as recessions, rising interest rates, rising inflation or a weakening exchange rate. Alternatively, they can hedge themselves against the negative implications of such macroeconomic changes on portfolio performance. In addition, the findings are important for the monetary authorities to better understand the implications of their policy changes on financial markets.
- Full Text:
- Date Issued: 2020
- Authors: Mapanda, Tungamirai Chisvuvo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stock price indexes -- South Africa , Interest rates -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/147445 , vital:38637
- Description: Purpose- The purpose of this paper is to analyse the relationship between changes in domestic macroeconomic variables and various indices of the JSE during the full time period, June 1995 to December 2018 and the sub-periods, June 1995 to June 2007 and July 2007 to December 2018. Design/ methodology/ approach- The paper employs the Autoregressive Distributed Lag (ARDL) model approach to cointegration using monthly data from June 1995 to December 2018. Findings- In terms of the long run, the results show that the coincident indicator measure of domestic economic activity is positively and significantly related to the various JSE indices for all study periods. In terms of inflation, the results show no relationship between inflation rate and the various indices for both whole period and June 1995 to June 2007 sub period. However for the July 2007 to December 2018 sub period, JSE All Share Index and JSE Top 40 Index are negatively related. For the real effective exchange rate, only the Consumer Services Index is positively related to the exchange rate in terms of June 1995 to June 2007 sub period. However, JSE All Share Index and JSE Top 40 Index are negatively related to the exchange rate in all study periods. In terms of the short term interest rate, for the whole period, JSE All Share Index, JSE Top 40 Index, Health Care Index and Telecommunications Index are negatively related to interest rate. In terms of the June 1995 to June 2007 sub period, JSE All Share Index and Industrials Index are negatively related to the short term interest rate. For the July 2007 to December 2018 sub period, Telecommunications Index and Technology Index are negatively related. In terms of the short run, the coincident indicator is positively and significantly related to the various JSE indices for all study periods. Inflation is not significantly related to any index in the whole period. In terms of the June 1995 to June 2007 sub period, Industrials Index and Financials Index are positively related to inflation and in the July 2007 to December 2018 sub period, Consumer Goods Index, Health Index and Consumer Services Index are negatively related to the inflation rate. The real effective exchange rate is positively and significantly related to the various JSE indices in the different study periods. In terms of the short term interest rate, for the whole period and the June 1995 to June 2007 sub period only the Technology Index is not significantly and negatively related to the short term interest rate, but for the July 2007 to December 2018 sub period, Top 40 Index, Telecommunications Index and Technology Index are positively related to the interest rate. Only the Financial Index is negatively related to short term interest rates during this sub period. Research Limitations- Not a lot literature was found on the relationship between macroeconomic variables and the various sector indices of the JSE. Most previous work, in the South African context focused just on the JSE All Share Index. Practical Implications- The findings can help investors diversify their portfolios into indices that benefit from expected changes in macroeconomic variables, such as recessions, rising interest rates, rising inflation or a weakening exchange rate. Alternatively, they can hedge themselves against the negative implications of such macroeconomic changes on portfolio performance. In addition, the findings are important for the monetary authorities to better understand the implications of their policy changes on financial markets.
- Full Text:
- Date Issued: 2020
Analytical evaluation of the effect of aggregate variation on Asphalt Mixture Properties
- Authors: Van Eck, Elandre
- Date: 2020
- Subjects: Aggregates (Building materials)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49639 , vital:41743
- Description: This research study aimed to conduct an analytical evaluation of the effect of aggregate grading on the properties of asphalt mixtures. This was achieved by obtaining asphalt mix designs from approved civil engineering organisations and determining the relationship between the aggregate grading and the corresponding properties of the asphalt mix designs.
- Full Text: false
- Date Issued: 2020
- Authors: Van Eck, Elandre
- Date: 2020
- Subjects: Aggregates (Building materials)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49639 , vital:41743
- Description: This research study aimed to conduct an analytical evaluation of the effect of aggregate grading on the properties of asphalt mixtures. This was achieved by obtaining asphalt mix designs from approved civil engineering organisations and determining the relationship between the aggregate grading and the corresponding properties of the asphalt mix designs.
- Full Text: false
- Date Issued: 2020
Application of section 197 of the Labour Relations Act in an insourcing context
- Authors: Mahlati, Nomphelo Miliswa
- Date: 2020
- Subjects: Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/47392 , vital:39974
- Description: The last two decades have been characterised by a phenomenal rise in the outsourcing of services to external service providers. The driver of this trend has been largely economic, since outsourcing offers more competitive price points for the same service at a comparable service level. Beyond the cost saving objective, the rationale for outsourcing has been to drive core strategy. However, with the economic slowdown, declining consumption and production are forcing entrepreneurs to change their way of thinking about the management of companies. Notably, in recent years there has been a small but a growing reversal of this trend where companies that have previously outsourced functions are being brought back in-house. One of the major concerns surrounding these changes of business strategies is the extent to which the employee rights are safeguarded.
- Full Text:
- Date Issued: 2020
- Authors: Mahlati, Nomphelo Miliswa
- Date: 2020
- Subjects: Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/47392 , vital:39974
- Description: The last two decades have been characterised by a phenomenal rise in the outsourcing of services to external service providers. The driver of this trend has been largely economic, since outsourcing offers more competitive price points for the same service at a comparable service level. Beyond the cost saving objective, the rationale for outsourcing has been to drive core strategy. However, with the economic slowdown, declining consumption and production are forcing entrepreneurs to change their way of thinking about the management of companies. Notably, in recent years there has been a small but a growing reversal of this trend where companies that have previously outsourced functions are being brought back in-house. One of the major concerns surrounding these changes of business strategies is the extent to which the employee rights are safeguarded.
- Full Text:
- Date Issued: 2020
Applying blockchain technology to aspects of electronic health records in South Africa: lessons learnt
- Authors: Adlam, Ryno
- Date: 2020
- Subjects: Blockchains (Databases) , Database security Data protection Medical records -- Data processing
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/45996 , vital:39405
- Description: The purpose of this study was to explore the applicability of blockchain technology as a viable alternative for the secure storage and distribution of electronic health records in a South African context. The adoption of electronic health records (EHRs) has grown over recent years. Electronic health records (EHRs) can be seen as electronic versions of patients’ medical history. EHRs promise benefits such as improving the quality of care, reducing medical errors, reducing costs, saving time, and enhancing the availability and sharing of medical records. Blockchain, in simple terms, could be seen as a distributed database controlled by a group of individuals. Blockchain technology differs from other distributed ledger technology by bundling unrelated data into blocks that are chained together in a linked-list manner, hence the name blockchain. Blockchain technology strives to provide desirable features, such as decentralization, immutability, audibility, and transparency. EHRs are traditionally constructed with a cloud-based infrastructure to promote the storing and distribution of medical records. These medical records are commonly stored in a centralized architecture, such as a relational database. The centralized architecture employed by EHRs may present a single point of failure. These kinds of failures may lead to data-breaches. The cloud-based infrastructure is effective and efficient from an availability standpoint. The increased availability of electronic health records has brought forth challenges related to the security and privacy of the patient’s medical records. The sensitive nature of EHRs attracts the attention of cyber-criminals. There has been a rise in the number of data breaches related to electronic health records. The traditional infrastructure used by electronic health records can no longer ensure the privacy and security of patient’s medical records. To determine whether blockchain is a viable alternative to these approaches, the main objective of this study was to compile a technical report on the applicability of aspects of blockchain technology to the secure storage and distribution of electronic health records. The study first conducted a literature review to gather background on the current state of electronic health records and blockchain technology. The results of the literature review were used to compile an initial report. Experiments were conducted with various aspects of blockchain technology to build a technical baseline and to ultimately validate the initial report. The insights gained from the experiments served to refine the initial report into a final technical report. The final deliverable of this study was to devise a technical report. The technical report serves as a generalized overview of the applicability of blockchain technology as a secure storage and distribution mechanism for electronic health records. The main topics covered by the technical report to outline the applicability of blockchain technology to EHRs are as follows: authentication, authorization, audit log, storage and transactions. The insights gained from the study illustrate that permissioned blockchain technology can enhance the traditional AAA security scheme employed by traditional EHRs. The AAA security scheme entails the use of certificate-based authentication and attributebased access control for authorization. Audit logs can be stored in a semi-decentralized architecture that can enhance the security and privacy of audit logs. Using blockchain technology for storing electronic health records might not be a viable alternative to traditional EHRs architecture. Blockchain technology violates certain privacy regulations as information is stored in a permanent manner. Furthermore, blockchain technology is not optimized for dealing with large volumes of data. However, blockchain technology could be used to store a cryptographic hash of electronic health records to ensure the integrity of records. Permissioned blockchain technology can enhance the EHRs transaction process by transacting health records in a peer-to-peer infrastructure. In doing so, the above-mentioned AAA security scheme can enhance the security, confidentiality, and integrity of electronic health records shared across organizational bounds.
- Full Text:
- Date Issued: 2020
- Authors: Adlam, Ryno
- Date: 2020
- Subjects: Blockchains (Databases) , Database security Data protection Medical records -- Data processing
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/45996 , vital:39405
- Description: The purpose of this study was to explore the applicability of blockchain technology as a viable alternative for the secure storage and distribution of electronic health records in a South African context. The adoption of electronic health records (EHRs) has grown over recent years. Electronic health records (EHRs) can be seen as electronic versions of patients’ medical history. EHRs promise benefits such as improving the quality of care, reducing medical errors, reducing costs, saving time, and enhancing the availability and sharing of medical records. Blockchain, in simple terms, could be seen as a distributed database controlled by a group of individuals. Blockchain technology differs from other distributed ledger technology by bundling unrelated data into blocks that are chained together in a linked-list manner, hence the name blockchain. Blockchain technology strives to provide desirable features, such as decentralization, immutability, audibility, and transparency. EHRs are traditionally constructed with a cloud-based infrastructure to promote the storing and distribution of medical records. These medical records are commonly stored in a centralized architecture, such as a relational database. The centralized architecture employed by EHRs may present a single point of failure. These kinds of failures may lead to data-breaches. The cloud-based infrastructure is effective and efficient from an availability standpoint. The increased availability of electronic health records has brought forth challenges related to the security and privacy of the patient’s medical records. The sensitive nature of EHRs attracts the attention of cyber-criminals. There has been a rise in the number of data breaches related to electronic health records. The traditional infrastructure used by electronic health records can no longer ensure the privacy and security of patient’s medical records. To determine whether blockchain is a viable alternative to these approaches, the main objective of this study was to compile a technical report on the applicability of aspects of blockchain technology to the secure storage and distribution of electronic health records. The study first conducted a literature review to gather background on the current state of electronic health records and blockchain technology. The results of the literature review were used to compile an initial report. Experiments were conducted with various aspects of blockchain technology to build a technical baseline and to ultimately validate the initial report. The insights gained from the experiments served to refine the initial report into a final technical report. The final deliverable of this study was to devise a technical report. The technical report serves as a generalized overview of the applicability of blockchain technology as a secure storage and distribution mechanism for electronic health records. The main topics covered by the technical report to outline the applicability of blockchain technology to EHRs are as follows: authentication, authorization, audit log, storage and transactions. The insights gained from the study illustrate that permissioned blockchain technology can enhance the traditional AAA security scheme employed by traditional EHRs. The AAA security scheme entails the use of certificate-based authentication and attributebased access control for authorization. Audit logs can be stored in a semi-decentralized architecture that can enhance the security and privacy of audit logs. Using blockchain technology for storing electronic health records might not be a viable alternative to traditional EHRs architecture. Blockchain technology violates certain privacy regulations as information is stored in a permanent manner. Furthermore, blockchain technology is not optimized for dealing with large volumes of data. However, blockchain technology could be used to store a cryptographic hash of electronic health records to ensure the integrity of records. Permissioned blockchain technology can enhance the EHRs transaction process by transacting health records in a peer-to-peer infrastructure. In doing so, the above-mentioned AAA security scheme can enhance the security, confidentiality, and integrity of electronic health records shared across organizational bounds.
- Full Text:
- Date Issued: 2020
Applying high-resolution remote sensing to quantify baboon damage at a sub-compartment level in pine stands in the Mpumalanga escarpment region of South Africa
- Authors: Ferreira, Regardt
- Date: 2020
- Subjects: Environmental sciences -- Remote sensing , Geographic information systems Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49082 , vital:41599
- Description: Managing risk in intensively managed monoculture plantation forests is an essential task to ensure sustainable yield and a continuous flow of forest products. However, since risks can be either biotic or abiotic, not all of them have a predictable pattern of spread, which can cause severe losses if management does not have the chance to implement mitigation action. Monitoring the change in forest health is vital as this provides the opportunity for preventative management and quantifies the amount of damage that management has to deal with. To provide this window of opportunity for appropriate action, constant monitoring is required. Until recently, forest health was measured through field surveys which provided adequate data. This procedure, however, is time consuming. Remote sensing has become very popular as a monitoring tool, due to its ability to provide assessment data in a fraction of the time. In this study, baboon damage in plantations along the Mpumalanga escarpment area of South Africa was monitored using remote sensing methods. While there are many methods of forest health monitoring using remote sensing, some approaches are less suitable as they either monitor damage caused at a plantation level, use lower spatial resolution (>10m) datasets or map damage using one available time period. The purpose of this study was first to establish the impact of baboon damage through time, using Sentinel-2 satellite imagery with all vegetation indices available, and the Extreme Gradient Boosting (XGboost) algorithm. The second part focused on analysing the damage at a tree level using PlanetScope imagery using a deep Learning approach. Overall, the study found that the use of Sentinel-2 data and PlanetScope data could accurately distinguish between the varying severity of baboon damage, achieving an accuracy of 95% and 82%. The processing time of the deep learning Artificial Neural Network (ANN) was greatly affected by the number of hidden layers and neurons used. Implementation of techniques used in this study has the potential to improve the accuracy of forest health monitoring in compartment forestry in South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Ferreira, Regardt
- Date: 2020
- Subjects: Environmental sciences -- Remote sensing , Geographic information systems Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49082 , vital:41599
- Description: Managing risk in intensively managed monoculture plantation forests is an essential task to ensure sustainable yield and a continuous flow of forest products. However, since risks can be either biotic or abiotic, not all of them have a predictable pattern of spread, which can cause severe losses if management does not have the chance to implement mitigation action. Monitoring the change in forest health is vital as this provides the opportunity for preventative management and quantifies the amount of damage that management has to deal with. To provide this window of opportunity for appropriate action, constant monitoring is required. Until recently, forest health was measured through field surveys which provided adequate data. This procedure, however, is time consuming. Remote sensing has become very popular as a monitoring tool, due to its ability to provide assessment data in a fraction of the time. In this study, baboon damage in plantations along the Mpumalanga escarpment area of South Africa was monitored using remote sensing methods. While there are many methods of forest health monitoring using remote sensing, some approaches are less suitable as they either monitor damage caused at a plantation level, use lower spatial resolution (>10m) datasets or map damage using one available time period. The purpose of this study was first to establish the impact of baboon damage through time, using Sentinel-2 satellite imagery with all vegetation indices available, and the Extreme Gradient Boosting (XGboost) algorithm. The second part focused on analysing the damage at a tree level using PlanetScope imagery using a deep Learning approach. Overall, the study found that the use of Sentinel-2 data and PlanetScope data could accurately distinguish between the varying severity of baboon damage, achieving an accuracy of 95% and 82%. The processing time of the deep learning Artificial Neural Network (ANN) was greatly affected by the number of hidden layers and neurons used. Implementation of techniques used in this study has the potential to improve the accuracy of forest health monitoring in compartment forestry in South Africa.
- Full Text:
- Date Issued: 2020
Applying the substitution augmentation modification redefinition model towards adoption of e-learning usage at Walter Sisulu University
- Authors: Mabona, Teoflax Anele
- Date: 2020
- Subjects: Educational technology -- South Africa Universities and colleges -- Computer-assisted instruction -- South Africa
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/49474 , vital:41724
- Description: The adoption of e-learning by universities around the world has grown drastically during this time of the Fourth Industrial Revolution. Most universities implement the full utilisation of e-learning, conducting classes only by using online course delivery. Some universities still prefer a blended learning approach where classes are presented to students using both the traditional way of teaching and online e-learning platforms. Walter Sisulu University (WSU) is one of those universities that uses blended learning. The university started using this approach in 2009, through a partnership between WSU and the Netherlands for learning and teaching enhancement using e-learning. The adoption and usage of e-learning in universities is a challenge, which some researchers have investigated. This study aimed to apply the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to enhance the adoption of e-learning and its usage at WSU. To obtain results, a quantitative method using approaches, such as WiseUp logs, WiseUp e-learning usage publications, WSU e-learning documents and literature, was applied. The study, according to the WiseUp logs, found that the e-learning levels at the university were low. Using the WiseUp e-learning usage publications, revealed that the university was still having some challenges regarding the low usage of WiseUp. Some of the students were not aware of the WiseUp platform as they said the system was only shown to them once and never again for continuous training. Most lecturers’ challenge was that the system was time-consuming to upload online content. This study used the WSU e-learning documents to show that the institution employed some initiatives for the adoption and usage of WiseUp, such as the LTD (Learning Teaching Development) department orientating students about WiseUp, just after their registration. The study ‘s objective was achieved, which was to apply the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to enhance the adoption and usage of e-learning at WSU. The study applied the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to provide a clear understanding of WSU’s position in terms of e-learning adoption and usage. The overall result from the study showed that WSU was based mostly on the first three levels of teaching and learning integration into technology, and in the enhancement level of the Substitution; Augmentation; Modification; Redefinition (SAMR) Model. The researcher noted that much still needed to be done because the usage of the system was still very low but its integration into teaching and learning was positive.
- Full Text:
- Date Issued: 2020
- Authors: Mabona, Teoflax Anele
- Date: 2020
- Subjects: Educational technology -- South Africa Universities and colleges -- Computer-assisted instruction -- South Africa
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/49474 , vital:41724
- Description: The adoption of e-learning by universities around the world has grown drastically during this time of the Fourth Industrial Revolution. Most universities implement the full utilisation of e-learning, conducting classes only by using online course delivery. Some universities still prefer a blended learning approach where classes are presented to students using both the traditional way of teaching and online e-learning platforms. Walter Sisulu University (WSU) is one of those universities that uses blended learning. The university started using this approach in 2009, through a partnership between WSU and the Netherlands for learning and teaching enhancement using e-learning. The adoption and usage of e-learning in universities is a challenge, which some researchers have investigated. This study aimed to apply the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to enhance the adoption of e-learning and its usage at WSU. To obtain results, a quantitative method using approaches, such as WiseUp logs, WiseUp e-learning usage publications, WSU e-learning documents and literature, was applied. The study, according to the WiseUp logs, found that the e-learning levels at the university were low. Using the WiseUp e-learning usage publications, revealed that the university was still having some challenges regarding the low usage of WiseUp. Some of the students were not aware of the WiseUp platform as they said the system was only shown to them once and never again for continuous training. Most lecturers’ challenge was that the system was time-consuming to upload online content. This study used the WSU e-learning documents to show that the institution employed some initiatives for the adoption and usage of WiseUp, such as the LTD (Learning Teaching Development) department orientating students about WiseUp, just after their registration. The study ‘s objective was achieved, which was to apply the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to enhance the adoption and usage of e-learning at WSU. The study applied the Substitution; Augmentation; Modification; Redefinition (SAMR) Model to provide a clear understanding of WSU’s position in terms of e-learning adoption and usage. The overall result from the study showed that WSU was based mostly on the first three levels of teaching and learning integration into technology, and in the enhancement level of the Substitution; Augmentation; Modification; Redefinition (SAMR) Model. The researcher noted that much still needed to be done because the usage of the system was still very low but its integration into teaching and learning was positive.
- Full Text:
- Date Issued: 2020
Approaches used by NGOs in managing HIV/AIDS programmes in the Eastern Cape
- Authors: Budaza, Silakhe
- Date: 2020
- Subjects: HIV(Disease)-- Psychological aspects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/49775 , vital:41799
- Description: The purpose of this research study was to explore the interventions NGOs used in addressing the prevalence of HIV/AIDS along with an exploration of the management and causal factors behind project failures and success. Five districts in the province of the Eastern Cape, South Africa were used in the study. The study had three objectives- the first being to identify the various approaches used to manage HIV/AIDS by NGOs; the second was to consider the influence HIV/AIDS policies on the health sector NGOs and finally the third objective of the study was to explore the monitoring and evaluation mechanism set in place to track progress, or lack of, in HIV/AIDS programs. The research design followed a qualitative methodology and data was gathered from ten participants through semi-structured interviews and supported by a document analysis of existing HIV and AIDS policies from both a national and provincial level which were qualitative. The findings showed that a lack of adequate or delayed funding affected the overall performance of NGOs as well as approaches such as home-based care and educational support programs. Resource mobilization and fundraising ought to be diversified so that there is a committed and varied pool of funds to enable the execution of HIV/AIDS services and programs. The government and other stakeholders should build on local capacity to implement these various programs and build financial, social and organizational sustainability.
- Full Text:
- Date Issued: 2020
- Authors: Budaza, Silakhe
- Date: 2020
- Subjects: HIV(Disease)-- Psychological aspects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/49775 , vital:41799
- Description: The purpose of this research study was to explore the interventions NGOs used in addressing the prevalence of HIV/AIDS along with an exploration of the management and causal factors behind project failures and success. Five districts in the province of the Eastern Cape, South Africa were used in the study. The study had three objectives- the first being to identify the various approaches used to manage HIV/AIDS by NGOs; the second was to consider the influence HIV/AIDS policies on the health sector NGOs and finally the third objective of the study was to explore the monitoring and evaluation mechanism set in place to track progress, or lack of, in HIV/AIDS programs. The research design followed a qualitative methodology and data was gathered from ten participants through semi-structured interviews and supported by a document analysis of existing HIV and AIDS policies from both a national and provincial level which were qualitative. The findings showed that a lack of adequate or delayed funding affected the overall performance of NGOs as well as approaches such as home-based care and educational support programs. Resource mobilization and fundraising ought to be diversified so that there is a committed and varied pool of funds to enable the execution of HIV/AIDS services and programs. The government and other stakeholders should build on local capacity to implement these various programs and build financial, social and organizational sustainability.
- Full Text:
- Date Issued: 2020
Approaches used by NGOs in managing HIV/AIDS programmes in the Eastern Cape
- Authors: Budaza, Silakhe
- Date: 2020
- Subjects: Non-governmental organizations -- South Africa , Disease management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/50457 , vital:42169
- Description: The purpose of this research study was to explore the interventions NGOs used in addressing the prevalence of HIV/AIDS along with an exploration of the management and causal factors behind project failures and success. Five districts in the province of the Eastern Cape, South Africa were used in the study. The study had three objectives- the first being to identify the various approaches used to manage HIV/AIDS by NGOs; the second was to consider the influence HIV/AIDS policies on the health sector NGOs and finally the third objective of the study was to explore the monitoring and evaluation mechanism set in place to track progress, or lack of, in HIV/AIDS programs. The research design followed a qualitative methodology and data was gathered from ten participants through semi-structured interviews and supported by a document analysis of existing HIV and AIDS policies from both a national and provincial level which were qualitative. The findings showed that a lack of adequate or delayed funding affected the overall performance of NGOs as well as approaches such as home-based care and educational support programs. In addition, the negative stigma associated with HIV/AIDS has been a looming issue since 2004 which continues to undermine efforts of NGOs in their means to manage HIV/AIDS. The consequences of stigma from the findings are treatment adherence issues and little to no attendance of HIV/AIDS programs provided by the respective NGOs. Effective planning and management along with capacitated staff and volunteers increased the positive outcome of HIV/AIDS programs and services offered by the NGOs. From the study findings, it is recommended that the planning of HIV/AIDS approaches should consider resource planning to avoid abandoning projects midway due to a lack of resources. The management and monitoring of NGOs within the health sector, dealing with epidemics such as HIV/AIDS need to build on flexibility in implementation and have effective risk assessments in place as a contingency, so that corrective action is taken. Resource mobilization and fundraising ought to be diversified so that there is a committed and varied pool of funds to enable the execution of HIV/AIDS services and programs. The government and other stakeholders should build on local capacity to implement these various programs and also build financial, social and organizational sustainability.
- Full Text:
- Date Issued: 2020
- Authors: Budaza, Silakhe
- Date: 2020
- Subjects: Non-governmental organizations -- South Africa , Disease management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/50457 , vital:42169
- Description: The purpose of this research study was to explore the interventions NGOs used in addressing the prevalence of HIV/AIDS along with an exploration of the management and causal factors behind project failures and success. Five districts in the province of the Eastern Cape, South Africa were used in the study. The study had three objectives- the first being to identify the various approaches used to manage HIV/AIDS by NGOs; the second was to consider the influence HIV/AIDS policies on the health sector NGOs and finally the third objective of the study was to explore the monitoring and evaluation mechanism set in place to track progress, or lack of, in HIV/AIDS programs. The research design followed a qualitative methodology and data was gathered from ten participants through semi-structured interviews and supported by a document analysis of existing HIV and AIDS policies from both a national and provincial level which were qualitative. The findings showed that a lack of adequate or delayed funding affected the overall performance of NGOs as well as approaches such as home-based care and educational support programs. In addition, the negative stigma associated with HIV/AIDS has been a looming issue since 2004 which continues to undermine efforts of NGOs in their means to manage HIV/AIDS. The consequences of stigma from the findings are treatment adherence issues and little to no attendance of HIV/AIDS programs provided by the respective NGOs. Effective planning and management along with capacitated staff and volunteers increased the positive outcome of HIV/AIDS programs and services offered by the NGOs. From the study findings, it is recommended that the planning of HIV/AIDS approaches should consider resource planning to avoid abandoning projects midway due to a lack of resources. The management and monitoring of NGOs within the health sector, dealing with epidemics such as HIV/AIDS need to build on flexibility in implementation and have effective risk assessments in place as a contingency, so that corrective action is taken. Resource mobilization and fundraising ought to be diversified so that there is a committed and varied pool of funds to enable the execution of HIV/AIDS services and programs. The government and other stakeholders should build on local capacity to implement these various programs and also build financial, social and organizational sustainability.
- Full Text:
- Date Issued: 2020
Assessing community structure and trophic interrelationships in three differently impacted headwater streams in the AmatholeWinterberg freshwater ecoregion, South Africa
- Authors: Matomela, Nonjabulo Happy
- Date: 2020
- Subjects: Stream ecology -- South Africa -- Eastern Cape , Freshwater animals -- Ecology -- South Africa -- Eastern Cape , Kat River (South Africa) -- , Lushington River (South Africa) , Elands River (South Africa) , Eyre River (South Africa) , Food chains (Ecology) -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/147653 , vital:38658
- Description: Afromontane regions represent some of the highly threatened ecosystems on the planet as they harbour endemic and often relic freshwater fauna. These ecologically sensitive ecosystems have been altered by multiple impacts, including invasion by non-native fishes, replacement of diverse indigenous vegetation with monoculture plantations, agricultural and mining activities, hydrological modifications, and degradation of instream habitats, with potential detrimental effects on aquatic community structures and food web dynamics. The aim of the present study was to compare spatio-temporal patterns of macroinvertebrate and fish communities as well as food web dynamics in three differently impacted headwater tributaries of the Kat River in the Amathole-Winterberg freshwater ecoregion in the Eastern Cape Province of South Africa. The upper Kat River catchment was the ideal model for purposes of the present study as it contains streams with varying degrees of human impact. The streams considered in the present study were (i) the Eyre River which was considered to closely represent near-natural conditions as it is the least impacted stream in this catchment, with the riparian zone dominated by relatively intact and diverse native woody vegetation, (ii) the Elands River whose catchment has been altered by agricultural activities, and (iii) the Lushington River, whose riparian zone has been heavily invaded by black wattle. The three headwater streams were generally distinguished based on the physical-chemical variables. The Elands River was characterised by high conductivity and total dissolved solids (TDS). In addition, the Elands River was more alkaline and relatively warmer than the other two rivers. This suggested the negative influence of agriculture activities on the water quality in the Elands River. In general, the Lushington and Eyre rivers had comparable physical and chemical variables. However, the Lushington River was generally characterised by low streamflow, likely as a consequent of black wattle which is known for altering hydrological regimes of streams .The Eyre River and Lushington River were comparable in terms of macroinvertebrate richness and diversity, whereas the Elands River was characterised by low macroinvertebrate diversity and richness. Redundancy analysis indicated that the macroinvertebrate communities were mostly influenced by seasonality, with land-use accounting for a small but significant difference in community composition. In comparison, the generalised linear mixed-effects models (GLMMs) showed that chubbyhead barb abundance was significantly influenced by land-use patterns. Evaluation of food web dynamics using stable isotope analysis revealed that the food web structure in the three rivers differed substantially as a result of land-use. Specifically, the Eyre River was characterised by less variation in stable isotope values of basal food sources and consequently, the consumer groups had a narrow isotopic breadth. In contrast, the Elands River was characterised by a wide variation in basal food sources and therefore, a wider isotopic breadth for consumers. The Lushington River was spatially variable in terms of basal sources and isotopic breadth for consumers. The study concluded that food webs and trophic interrelationships were a more informative indicator of land-use than community structure was in evaluating the impact of land-use patterns on aquatic communities. In addition, future studies should seek to investigate food webs interrelationships in addition to community structure to infer a more conclusive river assessment.
- Full Text:
- Date Issued: 2020
- Authors: Matomela, Nonjabulo Happy
- Date: 2020
- Subjects: Stream ecology -- South Africa -- Eastern Cape , Freshwater animals -- Ecology -- South Africa -- Eastern Cape , Kat River (South Africa) -- , Lushington River (South Africa) , Elands River (South Africa) , Eyre River (South Africa) , Food chains (Ecology) -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/147653 , vital:38658
- Description: Afromontane regions represent some of the highly threatened ecosystems on the planet as they harbour endemic and often relic freshwater fauna. These ecologically sensitive ecosystems have been altered by multiple impacts, including invasion by non-native fishes, replacement of diverse indigenous vegetation with monoculture plantations, agricultural and mining activities, hydrological modifications, and degradation of instream habitats, with potential detrimental effects on aquatic community structures and food web dynamics. The aim of the present study was to compare spatio-temporal patterns of macroinvertebrate and fish communities as well as food web dynamics in three differently impacted headwater tributaries of the Kat River in the Amathole-Winterberg freshwater ecoregion in the Eastern Cape Province of South Africa. The upper Kat River catchment was the ideal model for purposes of the present study as it contains streams with varying degrees of human impact. The streams considered in the present study were (i) the Eyre River which was considered to closely represent near-natural conditions as it is the least impacted stream in this catchment, with the riparian zone dominated by relatively intact and diverse native woody vegetation, (ii) the Elands River whose catchment has been altered by agricultural activities, and (iii) the Lushington River, whose riparian zone has been heavily invaded by black wattle. The three headwater streams were generally distinguished based on the physical-chemical variables. The Elands River was characterised by high conductivity and total dissolved solids (TDS). In addition, the Elands River was more alkaline and relatively warmer than the other two rivers. This suggested the negative influence of agriculture activities on the water quality in the Elands River. In general, the Lushington and Eyre rivers had comparable physical and chemical variables. However, the Lushington River was generally characterised by low streamflow, likely as a consequent of black wattle which is known for altering hydrological regimes of streams .The Eyre River and Lushington River were comparable in terms of macroinvertebrate richness and diversity, whereas the Elands River was characterised by low macroinvertebrate diversity and richness. Redundancy analysis indicated that the macroinvertebrate communities were mostly influenced by seasonality, with land-use accounting for a small but significant difference in community composition. In comparison, the generalised linear mixed-effects models (GLMMs) showed that chubbyhead barb abundance was significantly influenced by land-use patterns. Evaluation of food web dynamics using stable isotope analysis revealed that the food web structure in the three rivers differed substantially as a result of land-use. Specifically, the Eyre River was characterised by less variation in stable isotope values of basal food sources and consequently, the consumer groups had a narrow isotopic breadth. In contrast, the Elands River was characterised by a wide variation in basal food sources and therefore, a wider isotopic breadth for consumers. The Lushington River was spatially variable in terms of basal sources and isotopic breadth for consumers. The study concluded that food webs and trophic interrelationships were a more informative indicator of land-use than community structure was in evaluating the impact of land-use patterns on aquatic communities. In addition, future studies should seek to investigate food webs interrelationships in addition to community structure to infer a more conclusive river assessment.
- Full Text:
- Date Issued: 2020
Assessing factors that mitigate business risks in the operations of emerging black-owned businesses in Mthatha, Eastern Cape
- Authors: Bovungana, Afrika Khanyiso
- Date: 2020
- Subjects: Business enterprises, Black
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/47502 , vital:40121
- Description: The study sought to assessfactors that mitigate business risks in the operations of emerging black-owned businesses in Mthatha, Eastern Cape. Small businesses in the country are significant contributorsto the South African economy,as they provide employment and development opportunities to disadvantaged communities. Many of these businesses are operationalbut have no formal systems in place to operate effectively. The lack of proper operating procedures can result ininefficiencies that often lead to the collapse and eventual failure of these businesses. Van Vuuren,a professor at the University of Pretoria,mentionedin a round table dialogue that in South Africa the early stage entrepreneurial activity rate has been recorded as9.2% whereas in similar developing economies such as Brazil early stage entrepreneurialactivity isapproximately 40%. The study utilised a quantitative research design and employed a Likert scale questionnaire on a sample of 64 black-owned small, medium and micro enterprises (SMMEs) chosen by means of a random probability samplingmethod. QuestionPro was used to analyse the data and discuss the findings of the study.The various factors identified and highlighted indicate the integral challenges faced by the black-owned SMMEs remain prevalent. The success or failure is dependent on dynamic interventions that are taken into consideration and implemented for the improvement of the environment and business life cycle of black-owned businesses.
- Full Text:
- Date Issued: 2020
- Authors: Bovungana, Afrika Khanyiso
- Date: 2020
- Subjects: Business enterprises, Black
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/47502 , vital:40121
- Description: The study sought to assessfactors that mitigate business risks in the operations of emerging black-owned businesses in Mthatha, Eastern Cape. Small businesses in the country are significant contributorsto the South African economy,as they provide employment and development opportunities to disadvantaged communities. Many of these businesses are operationalbut have no formal systems in place to operate effectively. The lack of proper operating procedures can result ininefficiencies that often lead to the collapse and eventual failure of these businesses. Van Vuuren,a professor at the University of Pretoria,mentionedin a round table dialogue that in South Africa the early stage entrepreneurial activity rate has been recorded as9.2% whereas in similar developing economies such as Brazil early stage entrepreneurialactivity isapproximately 40%. The study utilised a quantitative research design and employed a Likert scale questionnaire on a sample of 64 black-owned small, medium and micro enterprises (SMMEs) chosen by means of a random probability samplingmethod. QuestionPro was used to analyse the data and discuss the findings of the study.The various factors identified and highlighted indicate the integral challenges faced by the black-owned SMMEs remain prevalent. The success or failure is dependent on dynamic interventions that are taken into consideration and implemented for the improvement of the environment and business life cycle of black-owned businesses.
- Full Text:
- Date Issued: 2020