The biotechnology of hard coal utilization as a bioprocess substrate
- Mutambanengwe, Cecil Clifford Zvandada
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2010
- Subjects: Coal -- Biotechnology Acid mine drainage Coal mines and mining -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3934 , http://hdl.handle.net/10962/d1003993
- Description: The development of coal biotechnology, using hard coal as a substrate, has been impeded by its low reactivity in biological processes. As a result, the more successful application studies have focused on lignitic soft coals. However, new studies have reported using biologically or geologically oxidized hard coal as a functional substrate option for bioprocess applications on a large scale. This study undertook a preliminary investigation into the feasibility of environmental applications of coal biotechnology using oxidized hard coal substrates in both anaerobic and aerobic processes with carbon dioxide, sulfate and oxygen as terminal electron acceptors. A preliminary characterization of the oxidized hard coal substrates was undertaken to determine and predict their viability and behavior as electron donors and carbon sources for environmental bioprocess applications of direct interest to the coal mining industry. Both biologically and geologically oxidized coal substrates showed loss of up to 17% and 52% carbon respectively and incorporation of oxygen ranging from 0.9 – 24%. The latter substrate showed greater loss of carbon and increased oxygenation. The biologically and geologically oxidized hard coal substrates were shown to partition readily into 23% and 32% organic humic acid, a 0.1% fulvic acid fraction and 65% and 59% inorganic and humin fractions respectively. These organic components were shown to be potentially available for biological consumption. In the unmodified hard coal substrate, partitioning was not observed and it did not perform as a functional substrate for any of the bioprocesses investigated. Where carbon dioxide was used as a terminal electron acceptor, methane production ranging from 9 – 26 mg CH4.g substrate-1 was demonstrated from both oxidized coal substrates. Geologically oxidized coal produced 30% more methane than biologically oxidized coal. Methane yields from the geologically oxidized coal in the presence and absence of a co-substrate were 5 – 13-fold higher than previous studies that used hard coal for methanogenesis. Based on these results, and that the development and optimization of the biological oxidation process is currently ongoing, further applications investigated in this study were undertaken using geologically oxidized coal. It was shown using pyrolysis gas chromatography mass spectrometry that the methanogenic system was dependent on the presence of an effective co-substrate supporting the breakdown of the complex organic structures within the oxidized hard coal substrate. Also that the accumulation of aromatic intermediate breakdown compounds predominantly including toluene, furfural, styrene and 2-methoxy vinyl phenol appeared to become inhibitory to both methanogenic and sulfidogenic reactions. This was shown to be a more likely cause of reactor failure rather than substrate exhaustion over time. Evidence of a reductive degradation pathway of the complex organic structures within the oxidized hard coal substrates was shown through the production, accumulation and utilization of volatile fatty acids including acetic, formic, propionic, butyric and valeric acids. Comparative analysis of the volatile fatty acids produced in this system showed that geologically oxidized coal produced 20% more of the volatile fatty acids profiled and double the total concentration compared to the biologically oxidized coal. The use of geologically oxidized hard coal as a functional substrate for biological sulfate reduction was demonstrated in the neutralization of a simulated acid mine drainage wastewater in both batch and continuous process operations. Results showed an increase in pH from pH 4.0 to ~ pH 8.0 with sulfide production rates of ~ 86 mgL-1.day-1 in the batch reactions, while the pH increased to pH 9.0 and sulfide production rates of up to 450 mgL-1.day-1 were measured in the continuous process studies using sand and coal up-flow packed bed reactors. Again, the requirement for an effective co-substrate was demonstrated with lactate shown to function as a true co-substrate in this system. However, a low cost alternative to lactate would need to emerge if the process was to function in large-scale commercial environmental treatment applications. In this regard, the aerobic growth and production of Neosartorya fischeri biomass (0.64 g.biomass.g SOC-1) was demonstrated using oxidized hard coal and glutamate as a co-substrate. Both can be produced from wastes generated on coal mines, with the fungal biomass generated in potentially large volumes. Preliminary demonstration of the use of the fungal biomass as a carbon and electron donor source for biological sulfate reduction was shown and thus that this could serve as an effective substrate for anaerobic environmental treatment processes. Based on these findings, an Integrated Coal Bioprocess model was proposed using oxidized hard coal as a substrate for environmental remediation applications on coal mines. In this approach, potential applications included methane recovery from waste coal, use of waste coal in the treatment of acid mine drainage waste waters and the recovery and use of humic acids in the rehabilitation of open cast mining soils. This study provided a first report demonstrating the use of biologically and geologically oxidized hard coals as bioprocess substrates in environmental bioremediation applications. It also provided an indication that follow-up bioengineering studies to investigate scaled-up applications of these findings would be warranted.
- Full Text:
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2010
- Subjects: Coal -- Biotechnology Acid mine drainage Coal mines and mining -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3934 , http://hdl.handle.net/10962/d1003993
- Description: The development of coal biotechnology, using hard coal as a substrate, has been impeded by its low reactivity in biological processes. As a result, the more successful application studies have focused on lignitic soft coals. However, new studies have reported using biologically or geologically oxidized hard coal as a functional substrate option for bioprocess applications on a large scale. This study undertook a preliminary investigation into the feasibility of environmental applications of coal biotechnology using oxidized hard coal substrates in both anaerobic and aerobic processes with carbon dioxide, sulfate and oxygen as terminal electron acceptors. A preliminary characterization of the oxidized hard coal substrates was undertaken to determine and predict their viability and behavior as electron donors and carbon sources for environmental bioprocess applications of direct interest to the coal mining industry. Both biologically and geologically oxidized coal substrates showed loss of up to 17% and 52% carbon respectively and incorporation of oxygen ranging from 0.9 – 24%. The latter substrate showed greater loss of carbon and increased oxygenation. The biologically and geologically oxidized hard coal substrates were shown to partition readily into 23% and 32% organic humic acid, a 0.1% fulvic acid fraction and 65% and 59% inorganic and humin fractions respectively. These organic components were shown to be potentially available for biological consumption. In the unmodified hard coal substrate, partitioning was not observed and it did not perform as a functional substrate for any of the bioprocesses investigated. Where carbon dioxide was used as a terminal electron acceptor, methane production ranging from 9 – 26 mg CH4.g substrate-1 was demonstrated from both oxidized coal substrates. Geologically oxidized coal produced 30% more methane than biologically oxidized coal. Methane yields from the geologically oxidized coal in the presence and absence of a co-substrate were 5 – 13-fold higher than previous studies that used hard coal for methanogenesis. Based on these results, and that the development and optimization of the biological oxidation process is currently ongoing, further applications investigated in this study were undertaken using geologically oxidized coal. It was shown using pyrolysis gas chromatography mass spectrometry that the methanogenic system was dependent on the presence of an effective co-substrate supporting the breakdown of the complex organic structures within the oxidized hard coal substrate. Also that the accumulation of aromatic intermediate breakdown compounds predominantly including toluene, furfural, styrene and 2-methoxy vinyl phenol appeared to become inhibitory to both methanogenic and sulfidogenic reactions. This was shown to be a more likely cause of reactor failure rather than substrate exhaustion over time. Evidence of a reductive degradation pathway of the complex organic structures within the oxidized hard coal substrates was shown through the production, accumulation and utilization of volatile fatty acids including acetic, formic, propionic, butyric and valeric acids. Comparative analysis of the volatile fatty acids produced in this system showed that geologically oxidized coal produced 20% more of the volatile fatty acids profiled and double the total concentration compared to the biologically oxidized coal. The use of geologically oxidized hard coal as a functional substrate for biological sulfate reduction was demonstrated in the neutralization of a simulated acid mine drainage wastewater in both batch and continuous process operations. Results showed an increase in pH from pH 4.0 to ~ pH 8.0 with sulfide production rates of ~ 86 mgL-1.day-1 in the batch reactions, while the pH increased to pH 9.0 and sulfide production rates of up to 450 mgL-1.day-1 were measured in the continuous process studies using sand and coal up-flow packed bed reactors. Again, the requirement for an effective co-substrate was demonstrated with lactate shown to function as a true co-substrate in this system. However, a low cost alternative to lactate would need to emerge if the process was to function in large-scale commercial environmental treatment applications. In this regard, the aerobic growth and production of Neosartorya fischeri biomass (0.64 g.biomass.g SOC-1) was demonstrated using oxidized hard coal and glutamate as a co-substrate. Both can be produced from wastes generated on coal mines, with the fungal biomass generated in potentially large volumes. Preliminary demonstration of the use of the fungal biomass as a carbon and electron donor source for biological sulfate reduction was shown and thus that this could serve as an effective substrate for anaerobic environmental treatment processes. Based on these findings, an Integrated Coal Bioprocess model was proposed using oxidized hard coal as a substrate for environmental remediation applications on coal mines. In this approach, potential applications included methane recovery from waste coal, use of waste coal in the treatment of acid mine drainage waste waters and the recovery and use of humic acids in the rehabilitation of open cast mining soils. This study provided a first report demonstrating the use of biologically and geologically oxidized hard coals as bioprocess substrates in environmental bioremediation applications. It also provided an indication that follow-up bioengineering studies to investigate scaled-up applications of these findings would be warranted.
- Full Text:
Isomorphism, institutional entrepreneurship and total quality management (TQM) : a case study in the implementation of quality management standards and excellence models in South African developmental local government
- Authors: Naidoo, Pravine
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape Political entrepreneurship -- South Africa -- Eastern Cape Total quality management Municipal services -- South Africa -- Eastern Cape -- Management Municipal services -- Customer services -- South Africa -- Eastern Cape Political leadership -- South Africa -- Eastern Cape Organizational effectiveness
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1193 , http://hdl.handle.net/10962/d1007141
- Description: Within the new constitutional order, South African local government has been afforded specific status and is protected as a distinctive sphere of government in terms of the Constitution Act 108 of 1996. Municipalities are no longer a mere function of national or provincial governments. In addition to this entrenched status, the Constitution and other developmental local government legislation vests local government with specific functions and responsibilities as part of the process of building a new democracy and promoting socio-economic development and upliftment. Consequently, local government managers are under constant pressure to improve the performance and quality of service delivery. They are expected to satisfy a number of stakeholders, achieve increases in efficiency, as well as attain developmental service delivery goals as contained in their Integrated Development Plan (IDP). Quality management standards and excellence models in support of the total quality management (TQM) philosophy are relatively new public management approaches that changes traditional organisational decision-making practices to deliver services to its customers in more effective and efficient ways. In essence, quality management standards and excellence models are performance management methodological practices, techniques and tools designed to meet and exceed public requirements. It accomplishes this through determining what constitutes excellence in customer service, and then empowering employees to a never-ending search for quality improvement in the delivery of services, in terms of the continuous improvement and continuous process improvement philosophies, of which total quality management (TQM) is premised on. Consequently, quality management standards and excellence models (such as the ISO 9001: 2008 QMS, ISO 14001: 2004 EMS, EFQM and SAEF Excellence Models) as methodological practices, techniques or tools in support of the critical factors (CFs) of the total quality management (TQM) philosophy, namely: (1) customer-based approach, (2) senior management commitment and leadership, (3) quality planning, (4) management based on facts, (5) continuous improvement, (6) involvement of all members of the organisation, (7) education and training, (8) teamwork, (9) communication systems, (10) learning, (11) process management, (12) co-operation with suppliers, and (13) organisational awareness and concern for the social and environmental context, can provide a framework by which to achieve the goals of effective and efficient service delivery in developmental local government, as they foster a culture of performance and accountability. Local government managers could use these quality and excellence methodological practices, techniques and tools, as a starting point to improve efficiencies in their municipalities, as the programmes afford them an opportunity to systematically evaluate the municipality and determine what leads to organisational success and deliverables. Institutional theory suggests that organisations are both influenced by and can influence the society in which they operate. Institutional theorists believe that the motivation for a change in internal practices might not only be performance related, but may primarily be to enhance or maintain the legitimacy of the respective institution. Institutional theory also focuses on the social contract that exists between the institution and society. This social contract is believed to represent the expectations of society. From an institutional point of view, it has been suggested that institutions may change and adopt the norms of society to appear legitimate to that society. This infers that when societal norms and values change, institutions will be expected to change. These societal pressures combined with legislative changes, require institutional entrepreneurs to respond to these isomorphic pressures, and will work to preserve the institution's legitimacy by incorporating, or at least appearing to incorporate, new practices, norms and values. The aim of this research study was to analyse within an institutional theory framework, the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy and developmental local government within two South African municipalities. The research investigation has been undertaken within the social constructionist paradigm and using the case study method. Interviews and documents were the data sources and thematic analysis was used as a tool to analyse the data by applying a theory-driven coding procedure. The findings from the two research sites, namely Makana Municipality in Grahamstown and Drakenstein Municipality in Paarl reveal that the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy in both municipalities was not a smooth process and there were many challenges such as political instability, lack of commitment on the part of the senior leadership and management, staff and skills shortages, resistance by staff to implementation and resource constraints. Institutional theory has proved to be useful in understanding why the Makana and Drakenstein Municipalities implemented quality management standards and excellence models. Because of coercive, mimetic and normative isomorphic pressures affecting the Makana and Drakenstein municipalities, change was imperative if these institutions were to remain relevant and legitimate in order to address its service delivery mandate of effectiveness and efficiency. Institutional theory provided a theoretical lens to understand and appreciate the pressures that affected the municipalities because of its new developmental mandate as encapsulated in new municipal legislation. It also assisted in understanding how institutional entrepreneurs responded to these pressures to conform. The implementation of quality management standards and excellence models in the Makana and Drakenstein municipalities was adversely affected by volatility amongst the political leadership of both municipalities. The successful implementation of these standards and models would require collective action from the political, bureaucratic and procedural entrepreneurs in order to enhance effective, efficient and accountable service delivery. However, in both the Makana and Drakenstein municipalities, institutional entrepreneurs, namely councillors and officials were not working together as a collective to implement quality management standards and excellence models. Evidence has shown that the absence of stable political leadership and noncooperation and collaboration amongst institutional entrepreneurs contributed significantly to the non-institutionalisation of quality management standards and excellence models in these Municipalities. This implies that legitimacy has not been achieved, due to institutional entrepreneurs not collaborating and collectively working with each other to implement the quality management standards and excellence models. Thus, this research study suggests that the strategic and collective role of the political and administrative leadership as institutional entrepreneurs is critical if the municipality is to achieve its aims and objectives, namely effective, efficient, and accountable service delivery in developmental local government. Recommendations in respect of future research and to practitioners have also been offered.
- Full Text:
- Authors: Naidoo, Pravine
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape Political entrepreneurship -- South Africa -- Eastern Cape Total quality management Municipal services -- South Africa -- Eastern Cape -- Management Municipal services -- Customer services -- South Africa -- Eastern Cape Political leadership -- South Africa -- Eastern Cape Organizational effectiveness
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1193 , http://hdl.handle.net/10962/d1007141
- Description: Within the new constitutional order, South African local government has been afforded specific status and is protected as a distinctive sphere of government in terms of the Constitution Act 108 of 1996. Municipalities are no longer a mere function of national or provincial governments. In addition to this entrenched status, the Constitution and other developmental local government legislation vests local government with specific functions and responsibilities as part of the process of building a new democracy and promoting socio-economic development and upliftment. Consequently, local government managers are under constant pressure to improve the performance and quality of service delivery. They are expected to satisfy a number of stakeholders, achieve increases in efficiency, as well as attain developmental service delivery goals as contained in their Integrated Development Plan (IDP). Quality management standards and excellence models in support of the total quality management (TQM) philosophy are relatively new public management approaches that changes traditional organisational decision-making practices to deliver services to its customers in more effective and efficient ways. In essence, quality management standards and excellence models are performance management methodological practices, techniques and tools designed to meet and exceed public requirements. It accomplishes this through determining what constitutes excellence in customer service, and then empowering employees to a never-ending search for quality improvement in the delivery of services, in terms of the continuous improvement and continuous process improvement philosophies, of which total quality management (TQM) is premised on. Consequently, quality management standards and excellence models (such as the ISO 9001: 2008 QMS, ISO 14001: 2004 EMS, EFQM and SAEF Excellence Models) as methodological practices, techniques or tools in support of the critical factors (CFs) of the total quality management (TQM) philosophy, namely: (1) customer-based approach, (2) senior management commitment and leadership, (3) quality planning, (4) management based on facts, (5) continuous improvement, (6) involvement of all members of the organisation, (7) education and training, (8) teamwork, (9) communication systems, (10) learning, (11) process management, (12) co-operation with suppliers, and (13) organisational awareness and concern for the social and environmental context, can provide a framework by which to achieve the goals of effective and efficient service delivery in developmental local government, as they foster a culture of performance and accountability. Local government managers could use these quality and excellence methodological practices, techniques and tools, as a starting point to improve efficiencies in their municipalities, as the programmes afford them an opportunity to systematically evaluate the municipality and determine what leads to organisational success and deliverables. Institutional theory suggests that organisations are both influenced by and can influence the society in which they operate. Institutional theorists believe that the motivation for a change in internal practices might not only be performance related, but may primarily be to enhance or maintain the legitimacy of the respective institution. Institutional theory also focuses on the social contract that exists between the institution and society. This social contract is believed to represent the expectations of society. From an institutional point of view, it has been suggested that institutions may change and adopt the norms of society to appear legitimate to that society. This infers that when societal norms and values change, institutions will be expected to change. These societal pressures combined with legislative changes, require institutional entrepreneurs to respond to these isomorphic pressures, and will work to preserve the institution's legitimacy by incorporating, or at least appearing to incorporate, new practices, norms and values. The aim of this research study was to analyse within an institutional theory framework, the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy and developmental local government within two South African municipalities. The research investigation has been undertaken within the social constructionist paradigm and using the case study method. Interviews and documents were the data sources and thematic analysis was used as a tool to analyse the data by applying a theory-driven coding procedure. The findings from the two research sites, namely Makana Municipality in Grahamstown and Drakenstein Municipality in Paarl reveal that the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy in both municipalities was not a smooth process and there were many challenges such as political instability, lack of commitment on the part of the senior leadership and management, staff and skills shortages, resistance by staff to implementation and resource constraints. Institutional theory has proved to be useful in understanding why the Makana and Drakenstein Municipalities implemented quality management standards and excellence models. Because of coercive, mimetic and normative isomorphic pressures affecting the Makana and Drakenstein municipalities, change was imperative if these institutions were to remain relevant and legitimate in order to address its service delivery mandate of effectiveness and efficiency. Institutional theory provided a theoretical lens to understand and appreciate the pressures that affected the municipalities because of its new developmental mandate as encapsulated in new municipal legislation. It also assisted in understanding how institutional entrepreneurs responded to these pressures to conform. The implementation of quality management standards and excellence models in the Makana and Drakenstein municipalities was adversely affected by volatility amongst the political leadership of both municipalities. The successful implementation of these standards and models would require collective action from the political, bureaucratic and procedural entrepreneurs in order to enhance effective, efficient and accountable service delivery. However, in both the Makana and Drakenstein municipalities, institutional entrepreneurs, namely councillors and officials were not working together as a collective to implement quality management standards and excellence models. Evidence has shown that the absence of stable political leadership and noncooperation and collaboration amongst institutional entrepreneurs contributed significantly to the non-institutionalisation of quality management standards and excellence models in these Municipalities. This implies that legitimacy has not been achieved, due to institutional entrepreneurs not collaborating and collectively working with each other to implement the quality management standards and excellence models. Thus, this research study suggests that the strategic and collective role of the political and administrative leadership as institutional entrepreneurs is critical if the municipality is to achieve its aims and objectives, namely effective, efficient, and accountable service delivery in developmental local government. Recommendations in respect of future research and to practitioners have also been offered.
- Full Text:
The integration of natural resource management into the curriculum of rural under-resourced schools : a Bernsteinian analysis
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2010
- Subjects: Conservation of natural resources -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa -- Eastern Cape Bernstein, Basil B Nature conservation -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4762 , http://hdl.handle.net/10962/d1007157
- Description: This study was motivated by the need to improve curriculum relevance in poor rural schools through contextualised teaching and learning based on the management of local natural resources. It involved four schools which are located in the Ngqunshwa Local Municipality of the Eastern Cape Province of South Africa. The study's aim was to provide insight into and better understanding of the curriculum implementation process regarding natural resource management (NRM) education in a poor rural education context. This was done by analysing the extent of NRM integration in pedagogic texts, activities and practices in the different fields which constitute the structure of the pedagogic system in this education sector. The study adopted an interpretivist approach to the analysis, which was based on indicators of the extent of NRM integration, and was informed by Bernstein's concepts of classification and curriculum recontextualisation, and his model of the structure of the pedagogic system. The items which were analysed included national and provincial Grade 10 Life Sciences curriculum documents, Grade 10 Life Sciences textbooks, in-service training workshops for Life Sciences teachers, and various school documents, activities and practices. The analysis also involved interviews with educators, and classroom observations of Grade 10 Life Sciences lessons. The results revealed a very high overall level of NRM integration in the Grade 10 Life Sciences curriculum documents produced at national and provincial levels. The overall level of NRM integration was also found to be very high in the Grade 10 Life Science textbooks that were analysed, but very low in the in-service teacher training workshops, and in the schools' documents, activities and practices, especially in the Grade 10 Life Sciences lessons, and in schools' end-of-year Grade 10 Life Sciences examination papers. The study makes a number of recommendations towards effective integration of NRM into the curriculum of Eastern Cape's rural poor schools which include more specific and explicit reference to NRM in the official Grade 10 Life Sciences curriculum documents, the provision of environmental education courses to district education staff and Grade 10 Life Sciences teachers, the training of teachers in the classroom use of textbooks and other educational materials, and regular monitoring of teachers' work. The study also exposes important knowledge gaps which need urgent research attention in order to enhance NRM education in the poor rural schools of the Eastern Cape. These include analysing power and control relationships between the various agencies and agents that are involved with curriculum implementation in this education sector, and conducting investigation into the creation of specialist NRM knowledge and into the quality of NRM knowledge that is transmitted as pedagogic discourse in schools. This study contributes to the fields of rural education and environmental education in South Africa, and to the growing interest in the study of curriculum from a sociology of education perspective in the context of the country’s post-apartheid curriculum reforms.
- Full Text:
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2010
- Subjects: Conservation of natural resources -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa -- Eastern Cape Bernstein, Basil B Nature conservation -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4762 , http://hdl.handle.net/10962/d1007157
- Description: This study was motivated by the need to improve curriculum relevance in poor rural schools through contextualised teaching and learning based on the management of local natural resources. It involved four schools which are located in the Ngqunshwa Local Municipality of the Eastern Cape Province of South Africa. The study's aim was to provide insight into and better understanding of the curriculum implementation process regarding natural resource management (NRM) education in a poor rural education context. This was done by analysing the extent of NRM integration in pedagogic texts, activities and practices in the different fields which constitute the structure of the pedagogic system in this education sector. The study adopted an interpretivist approach to the analysis, which was based on indicators of the extent of NRM integration, and was informed by Bernstein's concepts of classification and curriculum recontextualisation, and his model of the structure of the pedagogic system. The items which were analysed included national and provincial Grade 10 Life Sciences curriculum documents, Grade 10 Life Sciences textbooks, in-service training workshops for Life Sciences teachers, and various school documents, activities and practices. The analysis also involved interviews with educators, and classroom observations of Grade 10 Life Sciences lessons. The results revealed a very high overall level of NRM integration in the Grade 10 Life Sciences curriculum documents produced at national and provincial levels. The overall level of NRM integration was also found to be very high in the Grade 10 Life Science textbooks that were analysed, but very low in the in-service teacher training workshops, and in the schools' documents, activities and practices, especially in the Grade 10 Life Sciences lessons, and in schools' end-of-year Grade 10 Life Sciences examination papers. The study makes a number of recommendations towards effective integration of NRM into the curriculum of Eastern Cape's rural poor schools which include more specific and explicit reference to NRM in the official Grade 10 Life Sciences curriculum documents, the provision of environmental education courses to district education staff and Grade 10 Life Sciences teachers, the training of teachers in the classroom use of textbooks and other educational materials, and regular monitoring of teachers' work. The study also exposes important knowledge gaps which need urgent research attention in order to enhance NRM education in the poor rural schools of the Eastern Cape. These include analysing power and control relationships between the various agencies and agents that are involved with curriculum implementation in this education sector, and conducting investigation into the creation of specialist NRM knowledge and into the quality of NRM knowledge that is transmitted as pedagogic discourse in schools. This study contributes to the fields of rural education and environmental education in South Africa, and to the growing interest in the study of curriculum from a sociology of education perspective in the context of the country’s post-apartheid curriculum reforms.
- Full Text:
The development and implementation of an evaluation for rural ICT projects in developing countries: an exploration of the Siyakhulu Living Lab, South Africa
- Authors: Pade Khene, Caroline Ileje
- Date: 2010
- Subjects: Siyakhula Living Lab Information technology -- South Africa -- Eastern Cape Rural development projects -- South Africa -- Eastern Cape Communication in economic development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1138 , http://hdl.handle.net/10962/d1002767
- Description: Rural development is a priority for poverty alleviation and development in developing countries, as the majority of the poor live in rural areas. Information and knowledge are key strategic resources for social and economic development as they empower rural communities with the ability to expand their choices through knowing what works best in their communities. Information and communication technologies (ICT) play a significant role in supporting rural development activities through providing supportive development information and creating essential interconnectivities between rural areas and more developed regions. However, rural ICT for development (ICT4D) is still at best a ‘working hypothesis’, faced with barriers and challenges associated with implementation and use in the rural environment; which threaten the success, sustainability or relevance of an ICT intervention. Many key questions remain largely unanswered, with no concrete or credible data to support a wide range of claims concerning the use of ICT for development. The evaluation of rural ICT projects is indispensable as it determines the need, effectiveness, impact, sustainability and extent of the awareness of the contribution such projects or programmes can make in poverty alleviation and development. Even so, existing ICT4D evaluations are confrontedwith shortcomings and challenges which influence the accuracy and reliability of evaluation conclusions. These shortcomings highlight the need to embark on a more comprehensive evaluation approach, sensitive to the rural environment. This research study was aimed at developing a comprehensive rural ICT evaluation framework to assess ICT projects and interventions that work toward supporting poverty eradication in rural communities. A multi-method approach was used to determine the multiple variables and components associated with rural ICT evaluation, and then to determine how these variables interrelate. The approach is founded on programme evaluation, ICT for development evaluation, and information systems evaluation. Firstly, key domains of programme evaluations combined with an exploration of the need and shortcomings of ICT4D evaluation, contributed to the development of a template to analyse existing ICT4D evaluation frameworks and information systems frameworks, based on a selection of criteria. The combined analysis of the two groups of frameworks compares and contrasts key characteristics that form the structure of a comprehensive evaluation. This analysis and a review of programme evaluation enabled the development of a Rural ICT Comprehensive Evaluation Framework (RICT-CEF) that encompasses the key components essential for a comprehensive evaluation of rural ICT projects. The theoretical framework aims to inform ICT intervention to improve and support rural development, through the application of fundamental and interconnected evaluation domains sensitive to the rural environment, throughout the project’s lifecycle. In order to obtain a better understanding and application of the RICT-CEF, a real-life case study investigation of the Siyakhula Living Lab reveals the lessons learned (shortcomings and suitability) from applying a prototype of the framework in a rural environment. The study is characteristically a rich case study, as the investigation occurs at two levels: 1) The actual evaluation of the project to obtain results to improve or guide the project, through applying domains of the RICT-CEF, and 2) Observing and investigating the application of the RICT-CEF framework to learn lessons from its evaluation process in a real-life context. The research study reveals the compatibility of the RICT-CEF framework in a real-life rural ICT intervention case, and builds lessons learned for enhancing the framework and guiding future evaluations in ICT4D. The RICT-CEF can possibly be viewed as a platform for the key domains and processes essential for the evaluation of ICT4D interventions; which can be customised for a variety of ICT projects, such that a comparative assessment of projects can provide measurement and further awareness of the impact of rural ICT in developing countries.
- Full Text:
- Authors: Pade Khene, Caroline Ileje
- Date: 2010
- Subjects: Siyakhula Living Lab Information technology -- South Africa -- Eastern Cape Rural development projects -- South Africa -- Eastern Cape Communication in economic development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1138 , http://hdl.handle.net/10962/d1002767
- Description: Rural development is a priority for poverty alleviation and development in developing countries, as the majority of the poor live in rural areas. Information and knowledge are key strategic resources for social and economic development as they empower rural communities with the ability to expand their choices through knowing what works best in their communities. Information and communication technologies (ICT) play a significant role in supporting rural development activities through providing supportive development information and creating essential interconnectivities between rural areas and more developed regions. However, rural ICT for development (ICT4D) is still at best a ‘working hypothesis’, faced with barriers and challenges associated with implementation and use in the rural environment; which threaten the success, sustainability or relevance of an ICT intervention. Many key questions remain largely unanswered, with no concrete or credible data to support a wide range of claims concerning the use of ICT for development. The evaluation of rural ICT projects is indispensable as it determines the need, effectiveness, impact, sustainability and extent of the awareness of the contribution such projects or programmes can make in poverty alleviation and development. Even so, existing ICT4D evaluations are confrontedwith shortcomings and challenges which influence the accuracy and reliability of evaluation conclusions. These shortcomings highlight the need to embark on a more comprehensive evaluation approach, sensitive to the rural environment. This research study was aimed at developing a comprehensive rural ICT evaluation framework to assess ICT projects and interventions that work toward supporting poverty eradication in rural communities. A multi-method approach was used to determine the multiple variables and components associated with rural ICT evaluation, and then to determine how these variables interrelate. The approach is founded on programme evaluation, ICT for development evaluation, and information systems evaluation. Firstly, key domains of programme evaluations combined with an exploration of the need and shortcomings of ICT4D evaluation, contributed to the development of a template to analyse existing ICT4D evaluation frameworks and information systems frameworks, based on a selection of criteria. The combined analysis of the two groups of frameworks compares and contrasts key characteristics that form the structure of a comprehensive evaluation. This analysis and a review of programme evaluation enabled the development of a Rural ICT Comprehensive Evaluation Framework (RICT-CEF) that encompasses the key components essential for a comprehensive evaluation of rural ICT projects. The theoretical framework aims to inform ICT intervention to improve and support rural development, through the application of fundamental and interconnected evaluation domains sensitive to the rural environment, throughout the project’s lifecycle. In order to obtain a better understanding and application of the RICT-CEF, a real-life case study investigation of the Siyakhula Living Lab reveals the lessons learned (shortcomings and suitability) from applying a prototype of the framework in a rural environment. The study is characteristically a rich case study, as the investigation occurs at two levels: 1) The actual evaluation of the project to obtain results to improve or guide the project, through applying domains of the RICT-CEF, and 2) Observing and investigating the application of the RICT-CEF framework to learn lessons from its evaluation process in a real-life context. The research study reveals the compatibility of the RICT-CEF framework in a real-life rural ICT intervention case, and builds lessons learned for enhancing the framework and guiding future evaluations in ICT4D. The RICT-CEF can possibly be viewed as a platform for the key domains and processes essential for the evaluation of ICT4D interventions; which can be customised for a variety of ICT projects, such that a comparative assessment of projects can provide measurement and further awareness of the impact of rural ICT in developing countries.
- Full Text:
Historical biogeography of the tribe Platypleurini Schmidt, 1918 (Hemiptera: Cicadidae) with a focus on Southern Africa
- Authors: Price, Benjamin Wills
- Date: 2010
- Subjects: Biogeography -- History -- Africa, Southern Cicadas -- Africa, Southern Cicada (Genus) -- Africa, Southern Biodiversity -- Africa, Southern Cicadas -- Variation -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5708 , http://hdl.handle.net/10962/d1005394
- Description: With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.
- Full Text:
- Authors: Price, Benjamin Wills
- Date: 2010
- Subjects: Biogeography -- History -- Africa, Southern Cicadas -- Africa, Southern Cicada (Genus) -- Africa, Southern Biodiversity -- Africa, Southern Cicadas -- Variation -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5708 , http://hdl.handle.net/10962/d1005394
- Description: With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.
- Full Text:
Rethinking South Africa's small-scale fisheries management paradigm and governance approach : evidence from the Eastern Cape
- Authors: Raemaekers, Serge
- Date: 2010
- Subjects: Fishery management -- South Africa -- Eastern Cape -- Case studies Fishery policy -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Economic aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Social aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5202 , http://hdl.handle.net/10962/d1003921
- Description: This thesis presents a first analysis of how the South African fisheries authority (MCM) has utilised its fisheries management toolbox and governance framework in response to the emerging biological, economic and social challenges of post-apartheid fisheries in the Eastern Cape Province. Despite recognition of the socio-economic circumstances of traditional subsistence fishers in the region, the national fisheries management authority implemented a 'target resource orientated' management approach similar to that used for South Africa's rights-based commercial fisheries. Anecdotal evidence of entrenched illegal fishing for abalone, spiny lobster, and species targeted by subsistence fishers however suggested that MCM's management approach was encountering serious problems, as the needs and circumstances of inshore fishers and fishing communities were not adequately being understood and addressed. A review of fisheries management literature therefore shaped the hypothesis that an underlying governance problem was responsible for the symptoms of management failure being observed. In this regard, management is seen as more concerned with the technical and regulatory measures of the day-to-day operations of regulated fisheries, while fisheries governance needs to take account of "the sum of legal, social, economic and political arrangements used to manage fisheries ... ". Thus, governance includes policy making and management decision-making, with simultaneous recognition of issues outside of the fisheries sector. It thus appeared that the underlying problem was rather one of broader fisheries governance and inappropriate governance objectives with consequent inappropriate resource management arrangements. This thesis set out to gather evidence to test this hypothesis.
- Full Text:
- Authors: Raemaekers, Serge
- Date: 2010
- Subjects: Fishery management -- South Africa -- Eastern Cape -- Case studies Fishery policy -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Economic aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Social aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5202 , http://hdl.handle.net/10962/d1003921
- Description: This thesis presents a first analysis of how the South African fisheries authority (MCM) has utilised its fisheries management toolbox and governance framework in response to the emerging biological, economic and social challenges of post-apartheid fisheries in the Eastern Cape Province. Despite recognition of the socio-economic circumstances of traditional subsistence fishers in the region, the national fisheries management authority implemented a 'target resource orientated' management approach similar to that used for South Africa's rights-based commercial fisheries. Anecdotal evidence of entrenched illegal fishing for abalone, spiny lobster, and species targeted by subsistence fishers however suggested that MCM's management approach was encountering serious problems, as the needs and circumstances of inshore fishers and fishing communities were not adequately being understood and addressed. A review of fisheries management literature therefore shaped the hypothesis that an underlying governance problem was responsible for the symptoms of management failure being observed. In this regard, management is seen as more concerned with the technical and regulatory measures of the day-to-day operations of regulated fisheries, while fisheries governance needs to take account of "the sum of legal, social, economic and political arrangements used to manage fisheries ... ". Thus, governance includes policy making and management decision-making, with simultaneous recognition of issues outside of the fisheries sector. It thus appeared that the underlying problem was rather one of broader fisheries governance and inappropriate governance objectives with consequent inappropriate resource management arrangements. This thesis set out to gather evidence to test this hypothesis.
- Full Text:
Lag length selection for vector error correction models
- Authors: Sharp, Gary David
- Date: 2010
- Subjects: Akaike Information Criterion Mathematical models -- Evaluation Autoregression (Statistics) Error analysis (Mathematics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5568 , http://hdl.handle.net/10962/d1002808
- Description: This thesis investigates the problem of model identification in a Vector Autoregressive framework. The study reviews the existing research, conducts an extensive simulation based analysis of thirteen information theoretic criterion (IC), one of which is a novel derivation. The simulation exercise considers the evaluation of seven alternative error restricted vector autoregressive models with four different lag lengths. Alternative sample sizes and parameterisations are also evaluated and compared to results in the existing literature. The results of the comparative analysis provide strong support for the efficiency based criterion of Akaike and in particular the selection capability of the novel criterion, referred to as a modified corrected Akaike information criterion, demonstrates useful finite sample properties.
- Full Text:
- Authors: Sharp, Gary David
- Date: 2010
- Subjects: Akaike Information Criterion Mathematical models -- Evaluation Autoregression (Statistics) Error analysis (Mathematics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5568 , http://hdl.handle.net/10962/d1002808
- Description: This thesis investigates the problem of model identification in a Vector Autoregressive framework. The study reviews the existing research, conducts an extensive simulation based analysis of thirteen information theoretic criterion (IC), one of which is a novel derivation. The simulation exercise considers the evaluation of seven alternative error restricted vector autoregressive models with four different lag lengths. Alternative sample sizes and parameterisations are also evaluated and compared to results in the existing literature. The results of the comparative analysis provide strong support for the efficiency based criterion of Akaike and in particular the selection capability of the novel criterion, referred to as a modified corrected Akaike information criterion, demonstrates useful finite sample properties.
- Full Text:
Challenges in topside ionospheric modelling over South Africa
- Authors: Sibanda, Patrick
- Date: 2010
- Subjects: Ionospheric electron density -- South Africa Neural networks (Computer science) Atmosphere, Upper Ionosphere
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5453 , http://hdl.handle.net/10962/d1005238
- Description: This thesis creates a basic framework and provides the information necessary to create a more accurate description of the topside ionosphere in terms of the altitude variation of the electron density (Ne) over the South African region. The detailed overview of various topside ionospheric modelling techniques, with specific emphasis on their implications for the efforts to model the South African topside, provides a starting point towards achieving the goals. The novelty of the thesis lies in the investigation of the applicabilityof three different techniques to model the South African topside ionosphere: (1) The possibility of using Artificial Neural Network (ANN) techniques for empirical modelling of the topside ionosphere based on the available, however irregularly sampled, topside sounder measurements. The goal of this model was to test the ability of ANN techniques to capture the complex relationships between the various ionospheric variables using irregularly distributed measurements. While this technique is promising, the method did not show significant improvement over the International Reference Ionosphere (IRI) model results when compared with the actual measurements. (2) Application of the diffusive equilibrium theory. Although based on sound physics foundations, the method only operates on a generalised level leading to results that are not necessarily unique. Furthermore, the approach relies on many ionospheric variables as inputs which are derived from other models whose accuracy is not verified. (3) Attempts to complement the standard functional techniques, (Chapman, Epstein, Exponential and Parabolic), with Global Positioning System (GPS) and ionosonde measurements in an effort to provide deeper insights into the actual conditions within the ionosphere. The vertical Ne distribution is reconstructed by linking together the different aspects of the constituent ions and their transition height by considering how they influence the shape of the profile. While this approach has not been tested against actual measurements, results show that the method could be potentially useful for topside ionospheric studies. Due to the limitations of each technique reviewed, this thesis observes that the employment of an approach that incorporates both theoretical onsiderations and empirical aspects has the potential to lead to a more accurate characterisation of the topside ionospheric behaviour, and resulting in improved models in terms of reliability and forecasting ability. The point is made that a topside sounder mission for South Africa would provide the required measured topside ionospheric data and answer the many science questions that this region poses as well as solving a number of the limitations set out in this thesis.
- Full Text:
- Authors: Sibanda, Patrick
- Date: 2010
- Subjects: Ionospheric electron density -- South Africa Neural networks (Computer science) Atmosphere, Upper Ionosphere
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5453 , http://hdl.handle.net/10962/d1005238
- Description: This thesis creates a basic framework and provides the information necessary to create a more accurate description of the topside ionosphere in terms of the altitude variation of the electron density (Ne) over the South African region. The detailed overview of various topside ionospheric modelling techniques, with specific emphasis on their implications for the efforts to model the South African topside, provides a starting point towards achieving the goals. The novelty of the thesis lies in the investigation of the applicabilityof three different techniques to model the South African topside ionosphere: (1) The possibility of using Artificial Neural Network (ANN) techniques for empirical modelling of the topside ionosphere based on the available, however irregularly sampled, topside sounder measurements. The goal of this model was to test the ability of ANN techniques to capture the complex relationships between the various ionospheric variables using irregularly distributed measurements. While this technique is promising, the method did not show significant improvement over the International Reference Ionosphere (IRI) model results when compared with the actual measurements. (2) Application of the diffusive equilibrium theory. Although based on sound physics foundations, the method only operates on a generalised level leading to results that are not necessarily unique. Furthermore, the approach relies on many ionospheric variables as inputs which are derived from other models whose accuracy is not verified. (3) Attempts to complement the standard functional techniques, (Chapman, Epstein, Exponential and Parabolic), with Global Positioning System (GPS) and ionosonde measurements in an effort to provide deeper insights into the actual conditions within the ionosphere. The vertical Ne distribution is reconstructed by linking together the different aspects of the constituent ions and their transition height by considering how they influence the shape of the profile. While this approach has not been tested against actual measurements, results show that the method could be potentially useful for topside ionospheric studies. Due to the limitations of each technique reviewed, this thesis observes that the employment of an approach that incorporates both theoretical onsiderations and empirical aspects has the potential to lead to a more accurate characterisation of the topside ionospheric behaviour, and resulting in improved models in terms of reliability and forecasting ability. The point is made that a topside sounder mission for South Africa would provide the required measured topside ionospheric data and answer the many science questions that this region poses as well as solving a number of the limitations set out in this thesis.
- Full Text:
Indigenous technology and culture in the technology curriculum : starting the conversation : a case study
- Authors: Vandeleur, Sonja
- Date: 2010
- Subjects: Curriculum evaluation -- South Africa Curriculum planning -- South Africa Education -- Curricula -- South Africa Technology -- Study and teaching -- South Africa Indigenous peoples -- Education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1573 , http://hdl.handle.net/10962/d1003455
- Description: Since the collapse of apartheid and the first democratic elections of 1994, education in South Africa has undergone fundamental transformation and part of this transformation was the reconstruction of the school curriculum. The new curriculum, known as Curriculum 2005 and developed in 1997, introduced Technology as a new learning area. This study is based on the inclusion of ‘indigenous technology and culture’, a new aspect introduced in a revision of Curriculum 2005. The broad goal of the study was to examine and explore pedagogic practice in relation to the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology. The study was informed by an examination of literature pertaining to philosophy of technology, indigenous knowledge systems and technology education. The review of the literature highlighted the contested nature of ‘indigenous knowledge systems’. Philosophies on the nature of technological knowledge were reviewed in order to explore the meaning of ‘technology’, and a comparative review of curriculum reform in regard to technology education in various parts of the world was conducted. This study presented an attempt to determine the rationale for the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology in South Africa and to explore and examine what teachers’ existing practices were in this regard. It also examined a process of participatory co-engagement with a focus group of teachers. This process was an attempt to implement ‘indigenous technology and culture’ of the curriculum in a more meaningful way. A case study approach using an in-depth, interpretive design was used. A questionnaire, document analysis, interviews and focus group discussions were used to conduct the investigation. What emerged from the data analysis was that there was unanimous support for the inclusion of ‘indigenous technology and culture’ in the technology curriculum, but implementation had been problematic. This was partly due to difficulties with the interpretation of this aspect in the curriculum as well as a lack of meaningful teaching and learning for various reasons. The study revealed that teachers face multiple dilemmas in implementing ‘indigenous technology and culture’ as an assessment standard. These dilemmas are pedagogical, political, conceptual, professional and cultural in nature. The intentions of the study were to build a comprehensive understanding of ‘indigenous technology and culture’ and to determine how a focus group of teachers were dealing with this new inclusion. The interpretive study concluded with implications and recommendations for further studies.
- Full Text:
- Authors: Vandeleur, Sonja
- Date: 2010
- Subjects: Curriculum evaluation -- South Africa Curriculum planning -- South Africa Education -- Curricula -- South Africa Technology -- Study and teaching -- South Africa Indigenous peoples -- Education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1573 , http://hdl.handle.net/10962/d1003455
- Description: Since the collapse of apartheid and the first democratic elections of 1994, education in South Africa has undergone fundamental transformation and part of this transformation was the reconstruction of the school curriculum. The new curriculum, known as Curriculum 2005 and developed in 1997, introduced Technology as a new learning area. This study is based on the inclusion of ‘indigenous technology and culture’, a new aspect introduced in a revision of Curriculum 2005. The broad goal of the study was to examine and explore pedagogic practice in relation to the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology. The study was informed by an examination of literature pertaining to philosophy of technology, indigenous knowledge systems and technology education. The review of the literature highlighted the contested nature of ‘indigenous knowledge systems’. Philosophies on the nature of technological knowledge were reviewed in order to explore the meaning of ‘technology’, and a comparative review of curriculum reform in regard to technology education in various parts of the world was conducted. This study presented an attempt to determine the rationale for the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology in South Africa and to explore and examine what teachers’ existing practices were in this regard. It also examined a process of participatory co-engagement with a focus group of teachers. This process was an attempt to implement ‘indigenous technology and culture’ of the curriculum in a more meaningful way. A case study approach using an in-depth, interpretive design was used. A questionnaire, document analysis, interviews and focus group discussions were used to conduct the investigation. What emerged from the data analysis was that there was unanimous support for the inclusion of ‘indigenous technology and culture’ in the technology curriculum, but implementation had been problematic. This was partly due to difficulties with the interpretation of this aspect in the curriculum as well as a lack of meaningful teaching and learning for various reasons. The study revealed that teachers face multiple dilemmas in implementing ‘indigenous technology and culture’ as an assessment standard. These dilemmas are pedagogical, political, conceptual, professional and cultural in nature. The intentions of the study were to build a comprehensive understanding of ‘indigenous technology and culture’ and to determine how a focus group of teachers were dealing with this new inclusion. The interpretive study concluded with implications and recommendations for further studies.
- Full Text:
Isolation and evolution of novel nucleoside phosphorylases
- Authors: Visser, Daniel Finsch
- Date: 2010
- Subjects: AIDS (Disease) -- Treatment -- Africa HIV Infections -- Treatment -- Africa AIDS (Disease) -- Patients -- Africa HIV-Positive persons -- Africa Antiretroviral agents Pyrimidine nucleotides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3972 , http://hdl.handle.net/10962/d1004031
- Description: Approximately 33.4 million people are living with HIV/AIDS. Of those, 97% live in low and middle income countries, with 22.4 million in sub-Saharan Africa. Only 42% of the people who require anti-retrovirals (ARVs) in low to middle income countries are receiving anti-retroviral therapy (ART). There is a need to develop novel and cost effective methods for producing antiretroviral drugs. Stavudine and azidothymidine (AZT) were identified as potential targets because they could both be produced through a common intermediate – 5 methyluridine (5-MU). It has been established that the biocatalytic production of 5-methyluridine is possible through a reaction known as transglycosylation, in a process which has not previously been demonstrated as commercially viable. A selection of biocatalysts were expressed either in recombinant E. coli strains or in the wild type organisms, purified and then screened for their ability to produce 5-MU. A combination of Bacillus halodurans purine nucleoside phosphorylase 1 (BHPNP1) and E. coli uridine phosphorylase (EcUP) gave the highest 5-MU yield (80%). This result represents the first combination of free enzymes from different organisms, giving high yields of 5-MU under high substrate conditions. Both enzymes were purified and successfully characterised. The established pH optimum was pH 7.0 for both enzymes. Temperature optima and stability data for BHPNP1 (70 C and t1/2 at 60 C of 20.8 h) indicated that the biocatalytic step was operating within the capabilities of this enzyme and would operate well at elevated temperatures (up to 60 C). Conversely, the temperature optimum and stability data for EcUP (optimum of 40 C and t1/2 at 60 C of 9.9 h) indicated that the enzyme remained active at 40 C for the duration of a 25 h biotransformation, but at 60 C would only be operating at 20% of its optimum activity and would lose activity rapidly. BHPNP1 and EcUP were used in a bench scale (650 ml) transglycosylation for the production of 5-MU. A 5-MU yield of 79.1% was obtained at this scale with a reactor productivity of 1.37 g.l-1.h-1. Iterative saturation mutagenesis was used to rapidly evolve EcUP for improved thermostability. A moderately high throughput colorimetric method was developed for screening the mutants based on the release of p-nitrophenol upon phosphorolysis of a pyrimidine nucleoside analogue. By screening under 20 000 clones the mutant UPL8 was isolated. The mutant enzyme showed an optimum temperature of 60 C and improved stability at 60 C (t1/2 = 17.3 h). The increase in stability of UPL8 is due to only 2 mutations (Lys235Arg, Gln236Ala). These mutations may have caused an increase in stability due to interactions with other structural units in the protein, stabilization of the entrance to the binding pocket, or by decreasing the flexibility of the α-helix at the N-terminus. Transglycosylation experiments showed that the mutant enzyme UPL8 is a superior catalyst for the production of 5-MU. A 300% increase in reactor productivity was noted when free enzyme preparations of UPL8 was combined with BHPNP1 at 1.5% m.m-1 substrate loading. The high yield of 5-MU (75-80% mol.mol-1) was maintained at 9% m.m-1 substrate loading. A commercially viable productivity of 31 g.l-1.h-1 was thus realised. Further optimisation of the process could produce still higher productivities. Future work in directed evolution of nucleoside phosphorylases is envisaged for improved stability and enhanced substrate range for application to other commercially relevant transglycosylation reactions.
- Full Text:
- Authors: Visser, Daniel Finsch
- Date: 2010
- Subjects: AIDS (Disease) -- Treatment -- Africa HIV Infections -- Treatment -- Africa AIDS (Disease) -- Patients -- Africa HIV-Positive persons -- Africa Antiretroviral agents Pyrimidine nucleotides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3972 , http://hdl.handle.net/10962/d1004031
- Description: Approximately 33.4 million people are living with HIV/AIDS. Of those, 97% live in low and middle income countries, with 22.4 million in sub-Saharan Africa. Only 42% of the people who require anti-retrovirals (ARVs) in low to middle income countries are receiving anti-retroviral therapy (ART). There is a need to develop novel and cost effective methods for producing antiretroviral drugs. Stavudine and azidothymidine (AZT) were identified as potential targets because they could both be produced through a common intermediate – 5 methyluridine (5-MU). It has been established that the biocatalytic production of 5-methyluridine is possible through a reaction known as transglycosylation, in a process which has not previously been demonstrated as commercially viable. A selection of biocatalysts were expressed either in recombinant E. coli strains or in the wild type organisms, purified and then screened for their ability to produce 5-MU. A combination of Bacillus halodurans purine nucleoside phosphorylase 1 (BHPNP1) and E. coli uridine phosphorylase (EcUP) gave the highest 5-MU yield (80%). This result represents the first combination of free enzymes from different organisms, giving high yields of 5-MU under high substrate conditions. Both enzymes were purified and successfully characterised. The established pH optimum was pH 7.0 for both enzymes. Temperature optima and stability data for BHPNP1 (70 C and t1/2 at 60 C of 20.8 h) indicated that the biocatalytic step was operating within the capabilities of this enzyme and would operate well at elevated temperatures (up to 60 C). Conversely, the temperature optimum and stability data for EcUP (optimum of 40 C and t1/2 at 60 C of 9.9 h) indicated that the enzyme remained active at 40 C for the duration of a 25 h biotransformation, but at 60 C would only be operating at 20% of its optimum activity and would lose activity rapidly. BHPNP1 and EcUP were used in a bench scale (650 ml) transglycosylation for the production of 5-MU. A 5-MU yield of 79.1% was obtained at this scale with a reactor productivity of 1.37 g.l-1.h-1. Iterative saturation mutagenesis was used to rapidly evolve EcUP for improved thermostability. A moderately high throughput colorimetric method was developed for screening the mutants based on the release of p-nitrophenol upon phosphorolysis of a pyrimidine nucleoside analogue. By screening under 20 000 clones the mutant UPL8 was isolated. The mutant enzyme showed an optimum temperature of 60 C and improved stability at 60 C (t1/2 = 17.3 h). The increase in stability of UPL8 is due to only 2 mutations (Lys235Arg, Gln236Ala). These mutations may have caused an increase in stability due to interactions with other structural units in the protein, stabilization of the entrance to the binding pocket, or by decreasing the flexibility of the α-helix at the N-terminus. Transglycosylation experiments showed that the mutant enzyme UPL8 is a superior catalyst for the production of 5-MU. A 300% increase in reactor productivity was noted when free enzyme preparations of UPL8 was combined with BHPNP1 at 1.5% m.m-1 substrate loading. The high yield of 5-MU (75-80% mol.mol-1) was maintained at 9% m.m-1 substrate loading. A commercially viable productivity of 31 g.l-1.h-1 was thus realised. Further optimisation of the process could produce still higher productivities. Future work in directed evolution of nucleoside phosphorylases is envisaged for improved stability and enhanced substrate range for application to other commercially relevant transglycosylation reactions.
- Full Text:
Intertidal patterns and processes : tracking the effects of coastline topography and settlement choice across life stages of the mussels perna perna and mytilus galloprovincialis
- Von Der Meden, Charles Eric Otto
- Authors: Von Der Meden, Charles Eric Otto
- Date: 2010
- Subjects: Mexilhao mussel -- Behavior -- South Africa Mytilus galloprovincialis -- Behavior -- South Africa Perna -- Behavior -- South Africa Mussels -- Ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5721 , http://hdl.handle.net/10962/d1005407
- Description: Within landscapes, spatial heterogeneity is common and specific landscape features can influence propagule dispersal by wind or water, affecting population connectivity and dynamics. Coastline topographic features, such as bays and headlands, have a variety of biophysical effects on nearshore oceanography, larval transport, retention and supply, and the processes of larval settlement and recruitment. Although this has been demonstrated in several parts of the world, engendering a perception of a general ‘bay effect’, few studies have investigated this generality in a single experiment or region, by replicating at the level of ‘bay’. The Agulhas biogeographic region of the south coast of South Africa is a useful system within which to test for such generality. Using the intertidal mussels Mytilus galloprovincialis and Perna perna as model organisms, patterns of adult distribution were surveyed across four large ‘halfheart’ bays and intervening stretches of open coast, providing replication at the level of ‘bay’ and duplication of ecologically similar species. In support of a general, pervasive influence of bays on intertidal populations, mussel cover was found to be greater in bays than on the open coast for both species, although the effect was strongest for M. galloprovincialis. To explain this adult distribution, settlement, post-settlement mortality and recruitment were examined over 12mo at the same sites, with the prediction that rates of each would favour larger bay populations. Contrary to this, an interaction between month and bay-status was found, with greater settlement and recruitment on the open coast than in bays reflecting extreme settlement and recruitment events at 3 westerly open coast sites during summer. Re-analysis excluding these outliers, revealed the expected effect, of greater settlement and recruitment in bays. While this indicates the broad generality of the bay effect, it highlights exceptions and the need for replication in time and space when examining landscape effects. Measuring post-settlement mortality required testing small-scale settlement behaviour on established and newly deployed settler collectors. It was found that all settlers preferred collectors with biofilm, but that primary settlers avoided conspecific settlers, while secondary settlers were attracted to them. With discrepancies in settler attraction to new and established collectors accounted for, initial (over 2d) and longer-term (over 7d) post-settlement mortality rates were found to be substantial (ca 60 %) for both species. No topographic effect on p-s mortality was evident. Finally, recruit-settler, adult-recruit and interspecies correlations were examined at regional and local scales. Synergistic (or neutral) effects maintained the initial settlement pattern in recruit and adult populations regionally, but not at local scales; striking interspecies correlations suggested the influence of common regional transport processes. Ultimately, the results emphasize the importance of the direction of effects in different life stages and at different spatial scales, and the possibility that antagonistic effects may mask even strong patterns.
- Full Text:
- Authors: Von Der Meden, Charles Eric Otto
- Date: 2010
- Subjects: Mexilhao mussel -- Behavior -- South Africa Mytilus galloprovincialis -- Behavior -- South Africa Perna -- Behavior -- South Africa Mussels -- Ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5721 , http://hdl.handle.net/10962/d1005407
- Description: Within landscapes, spatial heterogeneity is common and specific landscape features can influence propagule dispersal by wind or water, affecting population connectivity and dynamics. Coastline topographic features, such as bays and headlands, have a variety of biophysical effects on nearshore oceanography, larval transport, retention and supply, and the processes of larval settlement and recruitment. Although this has been demonstrated in several parts of the world, engendering a perception of a general ‘bay effect’, few studies have investigated this generality in a single experiment or region, by replicating at the level of ‘bay’. The Agulhas biogeographic region of the south coast of South Africa is a useful system within which to test for such generality. Using the intertidal mussels Mytilus galloprovincialis and Perna perna as model organisms, patterns of adult distribution were surveyed across four large ‘halfheart’ bays and intervening stretches of open coast, providing replication at the level of ‘bay’ and duplication of ecologically similar species. In support of a general, pervasive influence of bays on intertidal populations, mussel cover was found to be greater in bays than on the open coast for both species, although the effect was strongest for M. galloprovincialis. To explain this adult distribution, settlement, post-settlement mortality and recruitment were examined over 12mo at the same sites, with the prediction that rates of each would favour larger bay populations. Contrary to this, an interaction between month and bay-status was found, with greater settlement and recruitment on the open coast than in bays reflecting extreme settlement and recruitment events at 3 westerly open coast sites during summer. Re-analysis excluding these outliers, revealed the expected effect, of greater settlement and recruitment in bays. While this indicates the broad generality of the bay effect, it highlights exceptions and the need for replication in time and space when examining landscape effects. Measuring post-settlement mortality required testing small-scale settlement behaviour on established and newly deployed settler collectors. It was found that all settlers preferred collectors with biofilm, but that primary settlers avoided conspecific settlers, while secondary settlers were attracted to them. With discrepancies in settler attraction to new and established collectors accounted for, initial (over 2d) and longer-term (over 7d) post-settlement mortality rates were found to be substantial (ca 60 %) for both species. No topographic effect on p-s mortality was evident. Finally, recruit-settler, adult-recruit and interspecies correlations were examined at regional and local scales. Synergistic (or neutral) effects maintained the initial settlement pattern in recruit and adult populations regionally, but not at local scales; striking interspecies correlations suggested the influence of common regional transport processes. Ultimately, the results emphasize the importance of the direction of effects in different life stages and at different spatial scales, and the possibility that antagonistic effects may mask even strong patterns.
- Full Text:
A social realist analysis of collaborative curriculum development processes in an academic department at a South African university
- Authors: Vorster, Jo-Anne
- Date: 2010
- Subjects: Rhodes University -- Curricula Journalism -- Study and teaching -- South Africa -- Grahamstown Curriculum planning -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3339 , http://hdl.handle.net/10962/d1004314
- Description: This study reports on a social-realist analysis of collaborative curriculum development in a journalism and media studies (JMS) department at a South African university. Archer's social-realist meta-theoretical framework is used to theorise about mechanisms that influence collaborative curriculum development within the context of the JMS Department. The thesis examines the cultural, structural and agential conditions that influenced the process of developing a JMS curriculum that aimed to integrate theory and practice. Bernstein's theories of knowledge recontextualisation and disciplinary knowledge structures are used in the analysis. Bernstein argues that knowledge recontextualisation constitutes a site of struggle. This thesis is an examination of the "struggles" for the epistemic-pedagogic device (Maton's elaboration of Bernstein's epistemic device) during the recontextualisation process that aimed to integrate media studies (MS) and media production (MP) in the JMS curriculum. Traditionally academic work has been an individual endeavour. However, given the growing need to work in disciplinary and inter-disciplinary teams, it is imperative to develop knowledge of the mechanisms that influence such practices. This thesis is a contribution to knowledge of collaborative processes at the level of an academic department in a university. It contributes to knowledge of cultural, structural and agential mechanisms that enable or constrain collaborative curriculum development within a particular kind of context. In addition it contributes to knowledge of the nature of leadership that may be necessary to facilitate productive collaborative relationships and practices in such a context. The curriculum development project reported on in this thesis was initiated in 2003; however, data collection for the study was conducted in 2006 when the curriculum for the fourth year (JMS 4) of the Bachelor of Journalism degree was developed. Since the JMS course prepares students to work as journalists or media workers it is necessary for the curriculum and pedagogy to be oriented both towards the academy and towards the media industries. The aim of the JMS degree is to develop students who will be critically reflexive journalists or media workers. As such the course is both theoretical (MS) and practical (MP). One of the findings of this research project is that the integration of MS and MP is a complex project given that the knowledge of the two disciplines is structured differently. MS is concept-dependent and some aspects of it can be applied to journalism and media practice, while MP is practical and thus context-dependent, though underpinned by theory. A further finding is that both the collaborative work and the integration project required different identity shifts from the lecturers in the JMS Department. Some were more able to make the shifts than others. The thesis shows that the knowledge recontextualisation struggles in the curriculum development processes of the Department of JMS centred around, inter alia, the setting of boundaries between the department and the media and journalism industries, between MS and MP and between MS theory and journalism theory. In addition, existing boundaries between MS and MP lecturers had to be traversed. These boundaries were circumscribed by, amongst other things, unequal power relations emanating from the higher status traditionally accorded to theoretical knowledge by universities, the tensions around the nature of journalism education and training and the differential properties and powers of the various lecturers within the department. The existence of a strong regulative discourse was found to be an important unifying mechanism in a tension-ridden context.
- Full Text:
- Authors: Vorster, Jo-Anne
- Date: 2010
- Subjects: Rhodes University -- Curricula Journalism -- Study and teaching -- South Africa -- Grahamstown Curriculum planning -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3339 , http://hdl.handle.net/10962/d1004314
- Description: This study reports on a social-realist analysis of collaborative curriculum development in a journalism and media studies (JMS) department at a South African university. Archer's social-realist meta-theoretical framework is used to theorise about mechanisms that influence collaborative curriculum development within the context of the JMS Department. The thesis examines the cultural, structural and agential conditions that influenced the process of developing a JMS curriculum that aimed to integrate theory and practice. Bernstein's theories of knowledge recontextualisation and disciplinary knowledge structures are used in the analysis. Bernstein argues that knowledge recontextualisation constitutes a site of struggle. This thesis is an examination of the "struggles" for the epistemic-pedagogic device (Maton's elaboration of Bernstein's epistemic device) during the recontextualisation process that aimed to integrate media studies (MS) and media production (MP) in the JMS curriculum. Traditionally academic work has been an individual endeavour. However, given the growing need to work in disciplinary and inter-disciplinary teams, it is imperative to develop knowledge of the mechanisms that influence such practices. This thesis is a contribution to knowledge of collaborative processes at the level of an academic department in a university. It contributes to knowledge of cultural, structural and agential mechanisms that enable or constrain collaborative curriculum development within a particular kind of context. In addition it contributes to knowledge of the nature of leadership that may be necessary to facilitate productive collaborative relationships and practices in such a context. The curriculum development project reported on in this thesis was initiated in 2003; however, data collection for the study was conducted in 2006 when the curriculum for the fourth year (JMS 4) of the Bachelor of Journalism degree was developed. Since the JMS course prepares students to work as journalists or media workers it is necessary for the curriculum and pedagogy to be oriented both towards the academy and towards the media industries. The aim of the JMS degree is to develop students who will be critically reflexive journalists or media workers. As such the course is both theoretical (MS) and practical (MP). One of the findings of this research project is that the integration of MS and MP is a complex project given that the knowledge of the two disciplines is structured differently. MS is concept-dependent and some aspects of it can be applied to journalism and media practice, while MP is practical and thus context-dependent, though underpinned by theory. A further finding is that both the collaborative work and the integration project required different identity shifts from the lecturers in the JMS Department. Some were more able to make the shifts than others. The thesis shows that the knowledge recontextualisation struggles in the curriculum development processes of the Department of JMS centred around, inter alia, the setting of boundaries between the department and the media and journalism industries, between MS and MP and between MS theory and journalism theory. In addition, existing boundaries between MS and MP lecturers had to be traversed. These boundaries were circumscribed by, amongst other things, unequal power relations emanating from the higher status traditionally accorded to theoretical knowledge by universities, the tensions around the nature of journalism education and training and the differential properties and powers of the various lecturers within the department. The existence of a strong regulative discourse was found to be an important unifying mechanism in a tension-ridden context.
- Full Text:
An investigation into the feasibility of incorporating didanosine into innovative solid lipid nanocarriers
- Authors: Wa Kasongo, Kasongo
- Date: 2010
- Subjects: Antiretroviral agents HIV infections -- Drug testing Didanosine Nanoparticles Drug delivery systems Nanostructured materials Lipids -- Therapeutic use
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3800 , http://hdl.handle.net/10962/d1003278
- Description: The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).
- Full Text:
- Authors: Wa Kasongo, Kasongo
- Date: 2010
- Subjects: Antiretroviral agents HIV infections -- Drug testing Didanosine Nanoparticles Drug delivery systems Nanostructured materials Lipids -- Therapeutic use
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3800 , http://hdl.handle.net/10962/d1003278
- Description: The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).
- Full Text:
Studies on mixed-species colonies of honeybees, Apis cerana and Apis mellifera
- Authors: Yang, Ming-Xian
- Date: 2010
- Subjects: Bees Apis cerana Honeybee Honeybee -- Behavior Bee culture Honeybee -- Physiology Insect societies Animal communication Bees -- Nests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5779 , http://hdl.handle.net/10962/d1005467
- Description: The honeybees Apis cerana and Apis mellifera are derived from the same ancestral base about two million years ago. With speciation and evolution, they have acquired many advanced living skills in common, but have also evolved very different living strategies due to different distributions. This thesis is an intensive study of the biology of the mixed-species colonies of these species, the aims of which were to investigate their behavioural relationships and uncover the evolutionary conserved features of their behaviours subsequent to speciation. The results show that the two species can form a stable society to perform normal tasks. First, workers of both species in the mixed-colonies could form the typical retinue behaviour to hetero-species queens, thus indicating that queen pheromones could be spread to and by both species. Secondly, both species did not show significantly different ovarian activation under hetero-species queens, suggesting that the queen pheromones more likely play a role of "honest signal" rather than a "repression" substance in the honeybee colonies. Thirdly, both species could mutually decode each other‘s waggle dances, with unexpectedly low misunderstanding; revealing that the dance language in a dark environment is quite adaptive for cavity-nesting honeybees. Fourthly, workers of both species could cooperate with each other in comb construction, although the combs they built contain many irregular cells. Interestingly, A. cerana workers could be stimulated by A. mellifera workers to perform this task, thus confirming self-organization theory in the colony. Fifthly, A. mellifera workers behaved more "defectively" in thermoregulation, but perhaps because A. cerana workers are more sensitive to changes in hive temperature. Given these differences in strategy, A. mellifera workers‘ performance might in fact reduce conflicts. Lastly, when faced with threats of predatory wasps, both species engaged in aggressive defence. Although they did not learn from each other‘s responses, species-specific strategies were adopted by each of them so that the defence of the mixed-colonies is very effective. I conclude that the two species can adapt to each other‘s efforts and task allocation is reasonably organized allowing mixed-species colonies to reach stability. These results suggest that all of the social behaviours discussed here were highly conserved following speciation. This thesis could provide some clues for the study of honeybee evolution from open-nesting to the transition of cavity-nesting.
- Full Text:
- Authors: Yang, Ming-Xian
- Date: 2010
- Subjects: Bees Apis cerana Honeybee Honeybee -- Behavior Bee culture Honeybee -- Physiology Insect societies Animal communication Bees -- Nests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5779 , http://hdl.handle.net/10962/d1005467
- Description: The honeybees Apis cerana and Apis mellifera are derived from the same ancestral base about two million years ago. With speciation and evolution, they have acquired many advanced living skills in common, but have also evolved very different living strategies due to different distributions. This thesis is an intensive study of the biology of the mixed-species colonies of these species, the aims of which were to investigate their behavioural relationships and uncover the evolutionary conserved features of their behaviours subsequent to speciation. The results show that the two species can form a stable society to perform normal tasks. First, workers of both species in the mixed-colonies could form the typical retinue behaviour to hetero-species queens, thus indicating that queen pheromones could be spread to and by both species. Secondly, both species did not show significantly different ovarian activation under hetero-species queens, suggesting that the queen pheromones more likely play a role of "honest signal" rather than a "repression" substance in the honeybee colonies. Thirdly, both species could mutually decode each other‘s waggle dances, with unexpectedly low misunderstanding; revealing that the dance language in a dark environment is quite adaptive for cavity-nesting honeybees. Fourthly, workers of both species could cooperate with each other in comb construction, although the combs they built contain many irregular cells. Interestingly, A. cerana workers could be stimulated by A. mellifera workers to perform this task, thus confirming self-organization theory in the colony. Fifthly, A. mellifera workers behaved more "defectively" in thermoregulation, but perhaps because A. cerana workers are more sensitive to changes in hive temperature. Given these differences in strategy, A. mellifera workers‘ performance might in fact reduce conflicts. Lastly, when faced with threats of predatory wasps, both species engaged in aggressive defence. Although they did not learn from each other‘s responses, species-specific strategies were adopted by each of them so that the defence of the mixed-colonies is very effective. I conclude that the two species can adapt to each other‘s efforts and task allocation is reasonably organized allowing mixed-species colonies to reach stability. These results suggest that all of the social behaviours discussed here were highly conserved following speciation. This thesis could provide some clues for the study of honeybee evolution from open-nesting to the transition of cavity-nesting.
- Full Text: