The characterization of the interaction between Streptococcus pneumoniae PspC and Homo sapiens pIgR
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
An evaluation of the mediation process that led to the agreement for the resolution of conflict in South Sudan in August 2015
- Authors: Osilo, Betty
- Date: 2018
- Subjects: Mediation -- Sudan , Conflict management -- Sudan Dispute resolution (Law) -- Sudan
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/34521 , vital:33389
- Description: In December 2013, a civil war broke out in South Sudan, following the dismissal of the former Vice-President Riek Machar by President Salva Kiir, who accused him of attempting a coup. This led to the splitting of the Sudan People’s Liberation Movement (SPLM) and saw the formation of the Sudan People’s Liberation Movement in Opposition (SPLM-IO). The political power struggle brought an ethnic dimension to the conflict with confrontations between the Dinka and the Nuer, the two largest ethnic groups in South Sudan. In August 2015, the Agreement for the Resolution of Conflict in South Sudan, which was spear headed by the Intergovernmental Authority on Development (IGAD), was signed by President Salva Kiir, Riek Machar, and the G10. Riek Machar returned to the capital Juba, and the Transitional Government of National Unity was formed with his swearing in as the first Vice-President. However, the agreement did not hold as just a day before South Sudan’s fifth independence anniversary; shootings erupted outside the presidential palace in Juba causing Machar to flee. The collapse of the transitional government and an increase in the intensity of violence has threatened the security of the South Sudanese and entire region. This evaluative qualitative study applied the critical research methodology to examine the reasons for the continued civil war in South Sudan. It assessed why intervention through mediation by IGAD, which is the recognised regional authority, failed to bring about peace and stability in South Sudan. The study also applied the Contingency Framework of Mediation to South Sudan’s mediation process to explain the theoretical complexities surrounding the inability for the militant factions to find a sustainable peace agreement. It was found that the regional players and the international community were more interested in pushing for their own interests rather than achieving sustainable peace and stability. The study concludes that provided both the adversaries and the mediators lack a genuine commitment to the mediation process, little can be done to achieve peace and stability in South Sudan.
- Full Text:
- Date Issued: 2018
- Authors: Osilo, Betty
- Date: 2018
- Subjects: Mediation -- Sudan , Conflict management -- Sudan Dispute resolution (Law) -- Sudan
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/34521 , vital:33389
- Description: In December 2013, a civil war broke out in South Sudan, following the dismissal of the former Vice-President Riek Machar by President Salva Kiir, who accused him of attempting a coup. This led to the splitting of the Sudan People’s Liberation Movement (SPLM) and saw the formation of the Sudan People’s Liberation Movement in Opposition (SPLM-IO). The political power struggle brought an ethnic dimension to the conflict with confrontations between the Dinka and the Nuer, the two largest ethnic groups in South Sudan. In August 2015, the Agreement for the Resolution of Conflict in South Sudan, which was spear headed by the Intergovernmental Authority on Development (IGAD), was signed by President Salva Kiir, Riek Machar, and the G10. Riek Machar returned to the capital Juba, and the Transitional Government of National Unity was formed with his swearing in as the first Vice-President. However, the agreement did not hold as just a day before South Sudan’s fifth independence anniversary; shootings erupted outside the presidential palace in Juba causing Machar to flee. The collapse of the transitional government and an increase in the intensity of violence has threatened the security of the South Sudanese and entire region. This evaluative qualitative study applied the critical research methodology to examine the reasons for the continued civil war in South Sudan. It assessed why intervention through mediation by IGAD, which is the recognised regional authority, failed to bring about peace and stability in South Sudan. The study also applied the Contingency Framework of Mediation to South Sudan’s mediation process to explain the theoretical complexities surrounding the inability for the militant factions to find a sustainable peace agreement. It was found that the regional players and the international community were more interested in pushing for their own interests rather than achieving sustainable peace and stability. The study concludes that provided both the adversaries and the mediators lack a genuine commitment to the mediation process, little can be done to achieve peace and stability in South Sudan.
- Full Text:
- Date Issued: 2018
Perceptions and current practices of Namibian midwives regarding the use of the cardio-tocograph as an informative labour monitoring tool for labouring women
- Authors: Uusiku, Laura Ingashipwa
- Date: 2017
- Subjects: Fetal heart rate monitoring Midwives -- Namibia , Midwifery -- Namibia Hospital patients -- Namibia -- Attitudes Medical care -- Namibia
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: http://hdl.handle.net/10948/21318 , vital:29477
- Description: Labour is a vital period for the labouring mothers, as it should bring with it the fulfilment of an expectation of having the baby that has been awaited. The health of the foetus which is to be born and that of the labouring mother are inextricably linked with each other which is why the labouring mother needs to be assessed and monitored carefully. The cardio-tocograph, which is a globally accepted method of diagnosis and assessment of the foetal status during labour is preferred to be used in monitoring labouring mothers, especially high- risk patients. Despite the evidence and information regarding the effectiveness of the use of the cardio-tocograph, midwives are still found not to be using it correctly, the reasons given that the women not always co-operate; do not keep the electrode and belt in place or cite the discomfort they experience from contraction. The objectives of this study were to: explore and describe the perceptions and current practice of Namibian midwives regarding the use of the cardio-tocograph as an informative labour- monitoring tool. Explore and describe how midwives working in labour wards in Namibia perceive informing laboring women of the use of the cardio-tocograph as an informative labour- monitoring tool and based on the results, develop an instruction guide for midwives working in the labour ward in intermediate hospital in Namibia that would serve as a guide on how to teach labouring women about the use of the cardio-tocograph as a labour- monitoring tool and enhance positive labor and delivery outcomes The study was conducted between May and June 2016, using a qualitative, explorative, descriptive and contextual design, following the necessary university approval and approval from other relevant authorities. The research population was midwives who work in labour wards at a public hospital in Namibia. Semi-structured interviews were used to collect data from purposively sampled participants using set criteria. A voice recorder was used to capture the interview with the permission of the participants. Seventeen midwives were interviewed of whom two were used for the pilot study. Data saturation determined the sufficient sample size. The collected data was analyzed using Tesch’s spiral method of data analysis with the assistance of an independent coder From the research findings, it emerged that midwives had varying perceptions regarding the use of the CTG machine. Midwives still perceive CTG interpretation as a challenge as a labour -monitoring tool and expressed a need for updates. Furthermore, midwives expressed the fact that they had limited communication with labouring women regarding the use of CTG. Based on the research findings and guided by Health Belief Model principles, three main guidelines were developed for midwives working in the labour ward in a public hospital in Namibia. These guidelines will serve as a tool to assist midwives in their teaching of labouring women about the use of the cardio-tocograph as a labour- monitoring tool, and the role to be played by labouring women during that monitoring period. Furthermore, recommendations for clinical nursing practice, nursing education and nursing research were developed. The researcher used literature control to ensure validation and integrity of the study. Trustworthiness, which was used to ensure rigour of the study, was guided by the principles of truth-value, transferability, dependability and confirmability. Ethical considerations were guided by the Belmont report adopting the principles of beneficence, respect for human dignity, justice and non-maleficence.
- Full Text:
- Date Issued: 2017
- Authors: Uusiku, Laura Ingashipwa
- Date: 2017
- Subjects: Fetal heart rate monitoring Midwives -- Namibia , Midwifery -- Namibia Hospital patients -- Namibia -- Attitudes Medical care -- Namibia
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: http://hdl.handle.net/10948/21318 , vital:29477
- Description: Labour is a vital period for the labouring mothers, as it should bring with it the fulfilment of an expectation of having the baby that has been awaited. The health of the foetus which is to be born and that of the labouring mother are inextricably linked with each other which is why the labouring mother needs to be assessed and monitored carefully. The cardio-tocograph, which is a globally accepted method of diagnosis and assessment of the foetal status during labour is preferred to be used in monitoring labouring mothers, especially high- risk patients. Despite the evidence and information regarding the effectiveness of the use of the cardio-tocograph, midwives are still found not to be using it correctly, the reasons given that the women not always co-operate; do not keep the electrode and belt in place or cite the discomfort they experience from contraction. The objectives of this study were to: explore and describe the perceptions and current practice of Namibian midwives regarding the use of the cardio-tocograph as an informative labour- monitoring tool. Explore and describe how midwives working in labour wards in Namibia perceive informing laboring women of the use of the cardio-tocograph as an informative labour- monitoring tool and based on the results, develop an instruction guide for midwives working in the labour ward in intermediate hospital in Namibia that would serve as a guide on how to teach labouring women about the use of the cardio-tocograph as a labour- monitoring tool and enhance positive labor and delivery outcomes The study was conducted between May and June 2016, using a qualitative, explorative, descriptive and contextual design, following the necessary university approval and approval from other relevant authorities. The research population was midwives who work in labour wards at a public hospital in Namibia. Semi-structured interviews were used to collect data from purposively sampled participants using set criteria. A voice recorder was used to capture the interview with the permission of the participants. Seventeen midwives were interviewed of whom two were used for the pilot study. Data saturation determined the sufficient sample size. The collected data was analyzed using Tesch’s spiral method of data analysis with the assistance of an independent coder From the research findings, it emerged that midwives had varying perceptions regarding the use of the CTG machine. Midwives still perceive CTG interpretation as a challenge as a labour -monitoring tool and expressed a need for updates. Furthermore, midwives expressed the fact that they had limited communication with labouring women regarding the use of CTG. Based on the research findings and guided by Health Belief Model principles, three main guidelines were developed for midwives working in the labour ward in a public hospital in Namibia. These guidelines will serve as a tool to assist midwives in their teaching of labouring women about the use of the cardio-tocograph as a labour- monitoring tool, and the role to be played by labouring women during that monitoring period. Furthermore, recommendations for clinical nursing practice, nursing education and nursing research were developed. The researcher used literature control to ensure validation and integrity of the study. Trustworthiness, which was used to ensure rigour of the study, was guided by the principles of truth-value, transferability, dependability and confirmability. Ethical considerations were guided by the Belmont report adopting the principles of beneficence, respect for human dignity, justice and non-maleficence.
- Full Text:
- Date Issued: 2017
Evaluating the effectiveness of talent management strategies in rural municipalities in the Eastern Cape
- Authors: Krexe, Owethu Mziwabantu
- Date: 2014
- Subjects: Civil service -- Personnel managementy -- South Africa -- Eastern Cape , Civil service -- Labor productivity -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/3215 , vital:20412
- Description: South Africa has three spheres of government, of which all are battling with the delivery of services to the population due to a number of challenges (Koketso and Rust, 2012). The local sphere of government was established in 1996 by the constitution of South Africa, for promoting social and economic development at municipal-based jurisdictions (Valeta and Walton, 2008). Pillay, Subban and Qwabe (2008) state that the South African public service lacks the skills required to perform their duties effectively and this is a key restraint. To emphasise this lack of skills, in an earlier study Meyer and Babb (2005) stated that management in the public sector is faced with a challenge of attracting employees with suitable skills for the job. Therefore, talent management has been identified as one of the strategies rural municipalities can use to improve performance. For this study, talent management is defined as a strategic process of attracting, recruiting, developing and retaining individuals who have the capability to make a significant difference to the current and future performance of the institution. The primary objective of the study was to evaluate the effectiveness of current talent management strategies used by rural municipalities and to provide these municipalities with a talent management model that can be of benefit to these institutions. This study analysed whether rural municipalities have talent management strategies and how effective those strategies were, by evaluating their current ways of attracting, developing and retaining their talent. A structured questionnaire was used as the measuring instrument. The study concluded by providing a talent model that could be used by rural municipalities.
- Full Text:
- Date Issued: 2014
- Authors: Krexe, Owethu Mziwabantu
- Date: 2014
- Subjects: Civil service -- Personnel managementy -- South Africa -- Eastern Cape , Civil service -- Labor productivity -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/3215 , vital:20412
- Description: South Africa has three spheres of government, of which all are battling with the delivery of services to the population due to a number of challenges (Koketso and Rust, 2012). The local sphere of government was established in 1996 by the constitution of South Africa, for promoting social and economic development at municipal-based jurisdictions (Valeta and Walton, 2008). Pillay, Subban and Qwabe (2008) state that the South African public service lacks the skills required to perform their duties effectively and this is a key restraint. To emphasise this lack of skills, in an earlier study Meyer and Babb (2005) stated that management in the public sector is faced with a challenge of attracting employees with suitable skills for the job. Therefore, talent management has been identified as one of the strategies rural municipalities can use to improve performance. For this study, talent management is defined as a strategic process of attracting, recruiting, developing and retaining individuals who have the capability to make a significant difference to the current and future performance of the institution. The primary objective of the study was to evaluate the effectiveness of current talent management strategies used by rural municipalities and to provide these municipalities with a talent management model that can be of benefit to these institutions. This study analysed whether rural municipalities have talent management strategies and how effective those strategies were, by evaluating their current ways of attracting, developing and retaining their talent. A structured questionnaire was used as the measuring instrument. The study concluded by providing a talent model that could be used by rural municipalities.
- Full Text:
- Date Issued: 2014
How can a potential franchisor establish a successful franchise in fast moving consumer goods
- Authors: Esmeraldo, Rosa
- Date: 2004
- Subjects: Franchises (Retail trade) -- South Africa , Franchises (Retail trade) -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10872 , http://hdl.handle.net/10948/235 , Franchises (Retail trade) -- South Africa , Franchises (Retail trade) -- Management
- Description: Franchising has become the latest trend in business expansion and business acquisition and with the South African franchising market estimated at being around 12% and growing rapidly, enormous potential for future growth is indicated. Companies both local and international are seeking franchise expansion opportunities in Africa despite the higher risks. The significance of implementing franchises into Africa is the filtering down of business opportunities to the small and medium enterprise sector. It can be said that franchising promotes business growth and private ownership, while improving the quality of life of the poor through its impact on income and employment. A franchise organisation that grows too quickly might not have the necessary ‘factors’ in place to support all of the units properly. In the survey conducted, it was indicated that the franchise business practice echoed the literature reviewed. All the steps necessary to establish a franchise are important but not necessarily as equal. The more matured franchisee needed less guidance from the franchisor and relied more on the business concept and location. Potential franchisors need to take the necessary steps to establish a franchise and treat each step as an important part of the franchise process.
- Full Text:
- Date Issued: 2004
- Authors: Esmeraldo, Rosa
- Date: 2004
- Subjects: Franchises (Retail trade) -- South Africa , Franchises (Retail trade) -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10872 , http://hdl.handle.net/10948/235 , Franchises (Retail trade) -- South Africa , Franchises (Retail trade) -- Management
- Description: Franchising has become the latest trend in business expansion and business acquisition and with the South African franchising market estimated at being around 12% and growing rapidly, enormous potential for future growth is indicated. Companies both local and international are seeking franchise expansion opportunities in Africa despite the higher risks. The significance of implementing franchises into Africa is the filtering down of business opportunities to the small and medium enterprise sector. It can be said that franchising promotes business growth and private ownership, while improving the quality of life of the poor through its impact on income and employment. A franchise organisation that grows too quickly might not have the necessary ‘factors’ in place to support all of the units properly. In the survey conducted, it was indicated that the franchise business practice echoed the literature reviewed. All the steps necessary to establish a franchise are important but not necessarily as equal. The more matured franchisee needed less guidance from the franchisor and relied more on the business concept and location. Potential franchisors need to take the necessary steps to establish a franchise and treat each step as an important part of the franchise process.
- Full Text:
- Date Issued: 2004
An investigation into the relationship marketing strategies applied by Eastern Cape based travel agents
- Authors: Fisher, Gary
- Date: 2003
- Subjects: Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech (Marketing)
- Identifier: vital:10766 , http://hdl.handle.net/10948/251 , Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Description: Relationship marketing has grown in importance. This growth affects all industries, including the tourism, hospitality and travel industry. Of particular importance is the bond of relationship marketing between suppliers (principals) and retailers (travel agents) in the distribution channel. The research was undertaken to: determine whether Eastern Cape travel agents perceive relationship marketing as important; establish, what the key elements of relationship marketing strategies are,according to literature; determine what marketing strategies are currently applied by Eastern Cape travel agents; provide guidelines to Eastern Cape travel agents to implement or improve their relationship marketing strategies. Fifty self-administered questionnaires were distributed to the entire population of travel agents in the Eastern Cape. A total of 30 travel agents responded. The empirical findings showed that: Most Eastern Cape travel agents perceived relationship marketing as important; Travel agents realized the importance of the management of such relationship marketing strategies; Most travel agents were aware of or used retention strategies to enhance relationship marketing strategies; Travel agents realized that to survive relationship marketing should be part of their future planning; All respondents believed that to successfully implement relationship marketing, all staff, from front-line to top-management, need to be committed to the programme. In conclusion, relationship marketing is growing in importance and all role players need to acknowledge and manage this trend. However, this research has shown that there is a paradigm shift as more travel agents are moving away from the traditional marketing to relationship marketing.
- Full Text:
- Date Issued: 2003
- Authors: Fisher, Gary
- Date: 2003
- Subjects: Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech (Marketing)
- Identifier: vital:10766 , http://hdl.handle.net/10948/251 , Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Description: Relationship marketing has grown in importance. This growth affects all industries, including the tourism, hospitality and travel industry. Of particular importance is the bond of relationship marketing between suppliers (principals) and retailers (travel agents) in the distribution channel. The research was undertaken to: determine whether Eastern Cape travel agents perceive relationship marketing as important; establish, what the key elements of relationship marketing strategies are,according to literature; determine what marketing strategies are currently applied by Eastern Cape travel agents; provide guidelines to Eastern Cape travel agents to implement or improve their relationship marketing strategies. Fifty self-administered questionnaires were distributed to the entire population of travel agents in the Eastern Cape. A total of 30 travel agents responded. The empirical findings showed that: Most Eastern Cape travel agents perceived relationship marketing as important; Travel agents realized the importance of the management of such relationship marketing strategies; Most travel agents were aware of or used retention strategies to enhance relationship marketing strategies; Travel agents realized that to survive relationship marketing should be part of their future planning; All respondents believed that to successfully implement relationship marketing, all staff, from front-line to top-management, need to be committed to the programme. In conclusion, relationship marketing is growing in importance and all role players need to acknowledge and manage this trend. However, this research has shown that there is a paradigm shift as more travel agents are moving away from the traditional marketing to relationship marketing.
- Full Text:
- Date Issued: 2003
The evaluation of potential improvements of barton pot oxides for lead acid batteries
- Authors: Geyer, Laurence Thomas
- Date: 2003
- Subjects: Lead oxides -- South Africa , Lead acid batteries -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10982 , http://hdl.handle.net/10948/233 , Lead oxides -- South Africa , Lead acid batteries -- South Africa
- Description: Lead Oxide (PbO) is the main material used for the preparation of the active material for the positive and negative electrodes in the lead acid battery where the electrochemical reaction that provides the electrical energy of the battery takes place. The particle size distribution and surface area characteristics of the lead oxide play a major role in the electrical performance of the completed battery. The two most commonly used processes to manufacture PbO in the lead acid battery industry are the Barton pot and the Ball mill processes. These two processes produce oxides that differ in particle size distribution, particle shape and surface area. It is generally accepted that the Ball mill process produces an oxide with a smaller mean particle size with a higher surface area and better initial electrical performance than the Barton pot process to the detriment of an initial higher capital and running cost. The study showed that it is possible to improve the surface area and particle size distribution characteristics of Barton pot oxide, by subsequently hammer milling the oxide particles before the paste manufacturing process. The results showed that there was an initial reduction in the particle size with an increase in the surface area. This increased the electrochemical performance in terms of the high rate discharge. However, further hammering of the oxide reduced the average particle size only slightly with little change in the surface area and a reduction in the electrochemical performance. The study showed that an improvement in Barton pot oxide can be achieved with a hammering of the oxide in order to obtain a uniform particle size with improved surface area and an improved high rate performance of the electrochemical cells made with such an oxide. As a comparison, the particle size and surface area characteristics of Ball mill lead oxide subjected to the hammer milling process was also studied. The results showed a similar effect to the Barton pot oxide on the particle size distribution. However, there was no appreciable change in the surface area due to the hammer milling process.
- Full Text:
- Date Issued: 2003
- Authors: Geyer, Laurence Thomas
- Date: 2003
- Subjects: Lead oxides -- South Africa , Lead acid batteries -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10982 , http://hdl.handle.net/10948/233 , Lead oxides -- South Africa , Lead acid batteries -- South Africa
- Description: Lead Oxide (PbO) is the main material used for the preparation of the active material for the positive and negative electrodes in the lead acid battery where the electrochemical reaction that provides the electrical energy of the battery takes place. The particle size distribution and surface area characteristics of the lead oxide play a major role in the electrical performance of the completed battery. The two most commonly used processes to manufacture PbO in the lead acid battery industry are the Barton pot and the Ball mill processes. These two processes produce oxides that differ in particle size distribution, particle shape and surface area. It is generally accepted that the Ball mill process produces an oxide with a smaller mean particle size with a higher surface area and better initial electrical performance than the Barton pot process to the detriment of an initial higher capital and running cost. The study showed that it is possible to improve the surface area and particle size distribution characteristics of Barton pot oxide, by subsequently hammer milling the oxide particles before the paste manufacturing process. The results showed that there was an initial reduction in the particle size with an increase in the surface area. This increased the electrochemical performance in terms of the high rate discharge. However, further hammering of the oxide reduced the average particle size only slightly with little change in the surface area and a reduction in the electrochemical performance. The study showed that an improvement in Barton pot oxide can be achieved with a hammering of the oxide in order to obtain a uniform particle size with improved surface area and an improved high rate performance of the electrochemical cells made with such an oxide. As a comparison, the particle size and surface area characteristics of Ball mill lead oxide subjected to the hammer milling process was also studied. The results showed a similar effect to the Barton pot oxide on the particle size distribution. However, there was no appreciable change in the surface area due to the hammer milling process.
- Full Text:
- Date Issued: 2003
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