Nanostructures and metallophthalocyanines : applications in microbial fuel cells
- Authors: Edwards, Sean
- Date: 2011
- Subjects: Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4107 , http://hdl.handle.net/10962/d1011742 , Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Description: Microbial fuel cells (MFCs) are a promising form of alternative energy capable of harnessing the potential energy stores in organic waste. The oxygen reduction reaction (ORR) forms an integral role in the generation of electricity in MFCs however it is also a potential obstacle in enhancing the performance of MFCs. Platinum, a commonly used catalyst for the ORR, is expensive and rare. Significant research has been conducted into developing alternative catalysts. Metallophthalocyanines (MPc) have garnered attention for use as catalysts. Iron phthalocyanine (FePc) has been shown to have catalytic activity towards the reduction of oxygen. Coupling of the catalyst to nanostructured carbon materials, such as multi-walled carbon nanotubes, has been observed to have several advantages as nanostructures have a high surface-to-volume ratio. In this study, we have attempted to assess the suitability of FePc, both its bulk and nanostructured form, as an oxygen reduction catalyst and acid functionalized multi-walled carbon nanotubes for use as a catalyst support using electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. We showed, for the first time, the catalytic nature of nanostructured FePc towards the ORR. Applying the data obtained from the electrochemical analyses, electrodes were modified using FePc and MWCNTs and applied to an Enterobacter cloacae-based MFC. Several operational parameters of the MFC, such as temperature and ionic strength, were optimized during the course of the study. We showed that optimized FePc:MWCNT-modified electrodes compared favourably to platinum-based electrodes in terms of power densities obtained in a microbial fuel cell.
- Full Text:
- Date Issued: 2011
- Authors: Edwards, Sean
- Date: 2011
- Subjects: Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4107 , http://hdl.handle.net/10962/d1011742 , Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Description: Microbial fuel cells (MFCs) are a promising form of alternative energy capable of harnessing the potential energy stores in organic waste. The oxygen reduction reaction (ORR) forms an integral role in the generation of electricity in MFCs however it is also a potential obstacle in enhancing the performance of MFCs. Platinum, a commonly used catalyst for the ORR, is expensive and rare. Significant research has been conducted into developing alternative catalysts. Metallophthalocyanines (MPc) have garnered attention for use as catalysts. Iron phthalocyanine (FePc) has been shown to have catalytic activity towards the reduction of oxygen. Coupling of the catalyst to nanostructured carbon materials, such as multi-walled carbon nanotubes, has been observed to have several advantages as nanostructures have a high surface-to-volume ratio. In this study, we have attempted to assess the suitability of FePc, both its bulk and nanostructured form, as an oxygen reduction catalyst and acid functionalized multi-walled carbon nanotubes for use as a catalyst support using electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. We showed, for the first time, the catalytic nature of nanostructured FePc towards the ORR. Applying the data obtained from the electrochemical analyses, electrodes were modified using FePc and MWCNTs and applied to an Enterobacter cloacae-based MFC. Several operational parameters of the MFC, such as temperature and ionic strength, were optimized during the course of the study. We showed that optimized FePc:MWCNT-modified electrodes compared favourably to platinum-based electrodes in terms of power densities obtained in a microbial fuel cell.
- Full Text:
- Date Issued: 2011
A psychobiography of Archbishop Emeritus Desmond Mpilo Tutu
- Authors: Eliastam, Liesl Marijke
- Date: 2011
- Subjects: Developmental psychology , Life cycle, Human -- Psychological aspects , Psychology -- Biographical methods , Personality -- Research -- Methodology , Emotional intelligence
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11856 , http://hdl.handle.net/10353/537 , Developmental psychology , Life cycle, Human -- Psychological aspects , Psychology -- Biographical methods , Personality -- Research -- Methodology , Emotional intelligence
- Description: Psychobiographies offer the illuminating experience of uncovering the story of an individual’s life through the lens of a psychological theory. Psychobiographies offer the chance to gain a deeper understanding of what makes that individual unique. This study aimed to explore and describe the emotional intelligence of Archbishop Emeritus Desmond Tutu according to Goleman’s (1998) theory of Emotional Intelligence. Tutu was chosen as a subject for this study because of his extraordinary life and accomplishments, and because he is regarded as a prominent figure of moral leadership in South Africa. A qualitative psychobiographical research method was utilised. Data was collected from both primary and secondary sources to enhance internal validity, and was then analysed according to Miles and Huberman’s (1994) approach. The findings suggest that Tutu applied all of the twenty five emotional intelligence capacities during his life, and that at times, some were used more extensively than others. This study is groundbreaking in that it is the first psychobiography on Desmond Tutu, and it is the first psychobiography undertaken at the University of Fort Hare. Psychobiographies offer an opportunity to evaluate the psychological theory which is applied. It was found that Goleman’s (1998) theory of Emotional Intelligence is supported by this study.
- Full Text:
- Date Issued: 2011
- Authors: Eliastam, Liesl Marijke
- Date: 2011
- Subjects: Developmental psychology , Life cycle, Human -- Psychological aspects , Psychology -- Biographical methods , Personality -- Research -- Methodology , Emotional intelligence
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11856 , http://hdl.handle.net/10353/537 , Developmental psychology , Life cycle, Human -- Psychological aspects , Psychology -- Biographical methods , Personality -- Research -- Methodology , Emotional intelligence
- Description: Psychobiographies offer the illuminating experience of uncovering the story of an individual’s life through the lens of a psychological theory. Psychobiographies offer the chance to gain a deeper understanding of what makes that individual unique. This study aimed to explore and describe the emotional intelligence of Archbishop Emeritus Desmond Tutu according to Goleman’s (1998) theory of Emotional Intelligence. Tutu was chosen as a subject for this study because of his extraordinary life and accomplishments, and because he is regarded as a prominent figure of moral leadership in South Africa. A qualitative psychobiographical research method was utilised. Data was collected from both primary and secondary sources to enhance internal validity, and was then analysed according to Miles and Huberman’s (1994) approach. The findings suggest that Tutu applied all of the twenty five emotional intelligence capacities during his life, and that at times, some were used more extensively than others. This study is groundbreaking in that it is the first psychobiography on Desmond Tutu, and it is the first psychobiography undertaken at the University of Fort Hare. Psychobiographies offer an opportunity to evaluate the psychological theory which is applied. It was found that Goleman’s (1998) theory of Emotional Intelligence is supported by this study.
- Full Text:
- Date Issued: 2011
Knowing, acting and being: Epistemological and ontological access in a Science Extended Studies course
- Authors: Ellery, Karen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69471 , vital:29540 , https://hdl.handle.net/10520/EJC37737
- Description: Gross participation and throughput rates in higher education institutions in South Africa indicate an inequitable and poorly functioning system. This interpretive study argues for an approach that enhances epistemological and ontological access and examines how an intervention that includes an overt approach in dealing with the nature of science, coupled with student involvement in an independent research project in a Science Extended Studies course, can enhance such access to higher education study. Analysis of project outcomes and student critical reflections indicated access to scientific and academic Discourses was enhanced through: developing improved procedural and conceptual scientific knowledge; meaningful engagement with the language, norms and conventions of the Discourse; integrating everyday knowledge into more abstract scientific knowledge; awareness of the process of validation of scientific knowledge, of the limitations of science, and of the impact of science on society; and transforming personally by developing scientific discursive identity and a sense of belonging. In conclusion, it is argued that curriculum interventions that focus on epistemological and ontological aspects of learning could appropriately be used throughout the higher education science sector.
- Full Text:
- Date Issued: 2011
- Authors: Ellery, Karen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69471 , vital:29540 , https://hdl.handle.net/10520/EJC37737
- Description: Gross participation and throughput rates in higher education institutions in South Africa indicate an inequitable and poorly functioning system. This interpretive study argues for an approach that enhances epistemological and ontological access and examines how an intervention that includes an overt approach in dealing with the nature of science, coupled with student involvement in an independent research project in a Science Extended Studies course, can enhance such access to higher education study. Analysis of project outcomes and student critical reflections indicated access to scientific and academic Discourses was enhanced through: developing improved procedural and conceptual scientific knowledge; meaningful engagement with the language, norms and conventions of the Discourse; integrating everyday knowledge into more abstract scientific knowledge; awareness of the process of validation of scientific knowledge, of the limitations of science, and of the impact of science on society; and transforming personally by developing scientific discursive identity and a sense of belonging. In conclusion, it is argued that curriculum interventions that focus on epistemological and ontological aspects of learning could appropriately be used throughout the higher education science sector.
- Full Text:
- Date Issued: 2011
A case study investigation into drama in education as an effective teaching methodology to support the goals of outcome based education
- Authors: Elliott, Terri Anne
- Date: 2011
- Subjects: Drama in education -- South Africa Competency based education -- South Africa Curriculum planning -- South Africa Student centered learning -- South Africa Critical thinking -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2160 , http://hdl.handle.net/10962/d1008306
- Description: The introduction of outcomes based education (OBE) in the form of Curriculum 2005 (C2005), the National Curriculum Statement (NCS) and the Revised National Curriculum Statement (RNCS) in post-apartheid South Africa resulted in a shift from a content-centred to a learner-centred view on education. This transition took place rapidly as the new government wanted to introduce a democratic education system after the divisive Bantu education system from Apartheid. However, after the changes were implemented, education in South Africa was theoretically outcomes based but practically many educators were still teaching in a content-centred manner. The research puts forward the proposal that drama-in-education (D-i-E) is a useful means by which to align the practical and theoretical goals of OBE within the context of South Africa's current RNCS. This hypothesis drives the main research question: "Can D-i-E be an effective teaching methodology to realise the goals of the RNCS and generate OBE learning environments in a South African high school?" D-i-E is a learner-centred teaching methodology and in practise it meets many of the goals and Critical Cross-Field Outcomes (CCFOs) of OBE. Some of these include the fact that learners can: • Practice problem-solving skills; • Engage with critical and creative thinking; • Grow cultural and aesthetic sensitivity; • Work effectively in groups; and ii. • Learn in inclusive environments that cater for different learning styles and levels. The research examines the use of D-i-E as an outcomes based methodology by which the RNCS could be implemented in the classroom. This is explored through the use of qualitative research in the form of a case study investigation at a South African high school. The case study was conducted with Grade 11 and Grade 12 Dramatic Arts learners and involves an analysis of a D-i-E approach to learning. The conclusion that D-i-E is an effective outcomes based teaching methodology which could assist educators in realising the RNCS was largely reached through participant observation of D-i-E classes and by analysing the learners' journals in which they reflected on D-i-E experiences. The learners' feedback about the experience was generally positive and they reflected that they found D-i-E beneficial because of the fact that it engaged them experientially. They also reflected that D-i-E provided them with a more meaningful and exciting way of learning. These findings are however only generalisable to the type of context (Dramatic Arts learners from a well-resourced girls' high school) in which the research was conducted. The findings provide detailed insight into a specific case study and may be beneficial to educators in South Africa who aim to make use of the same or similar methodologies in their classroom practice. D-i-E also supports many of the underlying tenants of OBE such as learner-centredness, learner diversity and inclusive learning, and can effectively aid educators in implementing the RNCS in an outcomes based way.
- Full Text:
- Date Issued: 2011
- Authors: Elliott, Terri Anne
- Date: 2011
- Subjects: Drama in education -- South Africa Competency based education -- South Africa Curriculum planning -- South Africa Student centered learning -- South Africa Critical thinking -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2160 , http://hdl.handle.net/10962/d1008306
- Description: The introduction of outcomes based education (OBE) in the form of Curriculum 2005 (C2005), the National Curriculum Statement (NCS) and the Revised National Curriculum Statement (RNCS) in post-apartheid South Africa resulted in a shift from a content-centred to a learner-centred view on education. This transition took place rapidly as the new government wanted to introduce a democratic education system after the divisive Bantu education system from Apartheid. However, after the changes were implemented, education in South Africa was theoretically outcomes based but practically many educators were still teaching in a content-centred manner. The research puts forward the proposal that drama-in-education (D-i-E) is a useful means by which to align the practical and theoretical goals of OBE within the context of South Africa's current RNCS. This hypothesis drives the main research question: "Can D-i-E be an effective teaching methodology to realise the goals of the RNCS and generate OBE learning environments in a South African high school?" D-i-E is a learner-centred teaching methodology and in practise it meets many of the goals and Critical Cross-Field Outcomes (CCFOs) of OBE. Some of these include the fact that learners can: • Practice problem-solving skills; • Engage with critical and creative thinking; • Grow cultural and aesthetic sensitivity; • Work effectively in groups; and ii. • Learn in inclusive environments that cater for different learning styles and levels. The research examines the use of D-i-E as an outcomes based methodology by which the RNCS could be implemented in the classroom. This is explored through the use of qualitative research in the form of a case study investigation at a South African high school. The case study was conducted with Grade 11 and Grade 12 Dramatic Arts learners and involves an analysis of a D-i-E approach to learning. The conclusion that D-i-E is an effective outcomes based teaching methodology which could assist educators in realising the RNCS was largely reached through participant observation of D-i-E classes and by analysing the learners' journals in which they reflected on D-i-E experiences. The learners' feedback about the experience was generally positive and they reflected that they found D-i-E beneficial because of the fact that it engaged them experientially. They also reflected that D-i-E provided them with a more meaningful and exciting way of learning. These findings are however only generalisable to the type of context (Dramatic Arts learners from a well-resourced girls' high school) in which the research was conducted. The findings provide detailed insight into a specific case study and may be beneficial to educators in South Africa who aim to make use of the same or similar methodologies in their classroom practice. D-i-E also supports many of the underlying tenants of OBE such as learner-centredness, learner diversity and inclusive learning, and can effectively aid educators in implementing the RNCS in an outcomes based way.
- Full Text:
- Date Issued: 2011
Performance improvement in South African construction
- Authors: Emuze, Fidelis Abumere
- Date: 2011
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9678 , http://hdl.handle.net/10948/1642 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Description: In general, dreams are conceived, ideas are conceptualised, and initiatives are embarked upon in order to alter the state of realities. Dreams change realities; when mechanisms are put in place to realise them, dreams succeed. However, anecdotal evidence as well as empirical findings has continued to reiterate the difficulties associated with realising dreams related to construction projects. Extending the „dream‟ analogy to the South African construction industry context therefore paints an uninspiring picture. Dreams associated with construction do not have a 100% chance of becoming realities as evident in reported poor project performance in the industry. Shattered dreams in the form of poor performing projects, poorly implemented construction processes, or worst, projects delivered at the expense of unexpected cost to the client as a direct result of poor H&S or time overruns, negate the intent of dreams. This thesis is primarily concerned with project performance related bottlenecks in South African construction. After an extensive review of related literature that entails the analysis of publications related to non-value adding activities (NVAAs), supply chain management (SCM), and system dynamics (SD) in the construction project management realm, an exhaustive mixed-mode quantitative survey was conducted among key participants in the South African infrastructure sector. Public sector clients, consulting engineers and contractors that were involved in civil engineering projects were surveyed repeatedly with approximately five survey instruments at convenient intervals. Results arising from the study, inter-alia, indicate that: an appreciable amount of NVAAs occur in South African construction; these NVAAs become further compounded when propagated into other value adding activities (VAAs) in the construction process; the identified NVAAs equally perpetrate the menace associated with poor performance to the detriment of the achievement of cost, H&S, quality, and time project targets, and the root cause of these NVAAs that often contribute to poor performance is not far from the much reported „shortage of skills‟ in South Africa. Notable contributions to the body of knowledge include SD models are extendable regardless of the source of their empirical data as evident in the qualitative models proposed in this study; within the SD domain, it is advisable to consider the „competence‟ of individuals assigned to tasks especially in a developing country as this study revealed that human resources issues predominate among the sources of NVAAs that eventuate in a range of poor project performance; the NVAAs that occur, and their causes on projects are perceived to be due to lapses and / or inadequacies that involved the entire construction supply chain; there is no single construction process / task that is immune from being affected by NVAAs; and within the South African, and by implication construction context generally iii in developing countries, the adequacy of required knowledge among project stakeholders is the most crucial determinant of project performance. As opposed to what is obtainable in developed countries, the construction industry in developing countries, particularly in South Africa, should take advantage of knowledge management (KM) techniques such as brainstorming, communities of practices, and face-to-face interactions. These techniques can be driven through appropriate mentorship programmes, industry focused built environment education, and other human resources driven avenues that do not necessarily require substantial investment in technologies, so that to a large extent organisations in the industry can prioritise KM, and thereafter, continually engage in it for future performance improvement. Using inferential statistical methods for hypotheses testing, and SD concepts for creating qualitative models led to a range of recommendations which, inter-alia, propose that halting the tide of NVAAs and poor performance requires the management of both tacit and explicit knowledge gained in construction; and most importantly, it requires the assurance that „competence‟ is the overriding criteria for selecting project partners, and also, for assigning either design or construction related activities to responsible parties involved in project realisation in South Africa. In effect, in order to engender a culture of continuous improvement in South African construction, other considerations should be subservient to „competence‟ in the construction supply chain. Competence must be located among everyone involved in project realisation, that is, enhancing the competence of all involved in project realisation is as good as ensuring performance improvement, which in turn, equates to the acceleration of project delivery in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Emuze, Fidelis Abumere
- Date: 2011
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9678 , http://hdl.handle.net/10948/1642 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Description: In general, dreams are conceived, ideas are conceptualised, and initiatives are embarked upon in order to alter the state of realities. Dreams change realities; when mechanisms are put in place to realise them, dreams succeed. However, anecdotal evidence as well as empirical findings has continued to reiterate the difficulties associated with realising dreams related to construction projects. Extending the „dream‟ analogy to the South African construction industry context therefore paints an uninspiring picture. Dreams associated with construction do not have a 100% chance of becoming realities as evident in reported poor project performance in the industry. Shattered dreams in the form of poor performing projects, poorly implemented construction processes, or worst, projects delivered at the expense of unexpected cost to the client as a direct result of poor H&S or time overruns, negate the intent of dreams. This thesis is primarily concerned with project performance related bottlenecks in South African construction. After an extensive review of related literature that entails the analysis of publications related to non-value adding activities (NVAAs), supply chain management (SCM), and system dynamics (SD) in the construction project management realm, an exhaustive mixed-mode quantitative survey was conducted among key participants in the South African infrastructure sector. Public sector clients, consulting engineers and contractors that were involved in civil engineering projects were surveyed repeatedly with approximately five survey instruments at convenient intervals. Results arising from the study, inter-alia, indicate that: an appreciable amount of NVAAs occur in South African construction; these NVAAs become further compounded when propagated into other value adding activities (VAAs) in the construction process; the identified NVAAs equally perpetrate the menace associated with poor performance to the detriment of the achievement of cost, H&S, quality, and time project targets, and the root cause of these NVAAs that often contribute to poor performance is not far from the much reported „shortage of skills‟ in South Africa. Notable contributions to the body of knowledge include SD models are extendable regardless of the source of their empirical data as evident in the qualitative models proposed in this study; within the SD domain, it is advisable to consider the „competence‟ of individuals assigned to tasks especially in a developing country as this study revealed that human resources issues predominate among the sources of NVAAs that eventuate in a range of poor project performance; the NVAAs that occur, and their causes on projects are perceived to be due to lapses and / or inadequacies that involved the entire construction supply chain; there is no single construction process / task that is immune from being affected by NVAAs; and within the South African, and by implication construction context generally iii in developing countries, the adequacy of required knowledge among project stakeholders is the most crucial determinant of project performance. As opposed to what is obtainable in developed countries, the construction industry in developing countries, particularly in South Africa, should take advantage of knowledge management (KM) techniques such as brainstorming, communities of practices, and face-to-face interactions. These techniques can be driven through appropriate mentorship programmes, industry focused built environment education, and other human resources driven avenues that do not necessarily require substantial investment in technologies, so that to a large extent organisations in the industry can prioritise KM, and thereafter, continually engage in it for future performance improvement. Using inferential statistical methods for hypotheses testing, and SD concepts for creating qualitative models led to a range of recommendations which, inter-alia, propose that halting the tide of NVAAs and poor performance requires the management of both tacit and explicit knowledge gained in construction; and most importantly, it requires the assurance that „competence‟ is the overriding criteria for selecting project partners, and also, for assigning either design or construction related activities to responsible parties involved in project realisation in South Africa. In effect, in order to engender a culture of continuous improvement in South African construction, other considerations should be subservient to „competence‟ in the construction supply chain. Competence must be located among everyone involved in project realisation, that is, enhancing the competence of all involved in project realisation is as good as ensuring performance improvement, which in turn, equates to the acceleration of project delivery in South Africa.
- Full Text:
- Date Issued: 2011
Synthesis and electrochemical properties of new tetra substituted cobalt phthalocyanine complexes, and their application in electrode modification for the electrocatalysis of l-cysteine
- Erdoğmuş, Ali, Booysen, Irvin Noel, Nyokong, Tebello
- Authors: Erdoğmuş, Ali , Booysen, Irvin Noel , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247893 , vital:51627 , xlink:href="https://doi.org/10.1016/j.synthmet.2010.11.028"
- Description: This study investigates the synthesis and characterization new peripherally (β) tetra-substituted 4-(2-mercaptoquinoline phthalocyaninato) Co(II) (CoPcSHQn, 3), and 4-(2-phenoxy-4-trifluoromethylpyridine phthalocyaninato) Co(II) (CoPcOHPy, 4). These complexes were characterized by elemental analysis, IR, mass and electronic spectroscopies and electrochemical methods. Both complexes show well resolved redox peaks attributed to both ring and metal based processes. Spectroelectrochemistry was used to confirm the assignments of the redox processes. For CoPcSHQn (3): CoIPc−2/CoIPc−3 (E1/2 = −1.25 V, I), CoIIPc−2/CoIPc−2 (E1/2 = −0.57 V, II), CoIIIPc−2/CoIIPc−2 (E1/2 = +0.45 V, IV) and an irreversible process at Ep = +1.05 V vs Ag|AgCl for CoIIIPc−1/CoIIIPc−2 (V). Redox couple III at E1/2 = −0.15 V was ascribed to aggregation. In the case of CoPcOHPy (4): CoIPc−2/CoIPc−3 (E1/2 = −1.13 V, I), CoIIPc−2/CoIPc−2 (E1/2 = −0.45 V, II), CoIIIPc−2/CoIIPc−2 at E1/2 = +0.21 V (IV), and CoIIIPc−1/CoIIIPc−2 (E1/2 = +1.01 V vs Ag|AgCl, V). Again III is associated with the aggregated species. Both complexes were electrodeposited on a glassy carbon electrode (GCE). For complex 3 self-assembled monolayers was also formed. The modified (CoPc-GCE) electrodes electrocatalytically detected L-cysteine at Ep = 0.62 V (3-GCE) and 0.59 V (4-GCE) vs Ag|AgCl.
- Full Text:
- Date Issued: 2011
- Authors: Erdoğmuş, Ali , Booysen, Irvin Noel , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247893 , vital:51627 , xlink:href="https://doi.org/10.1016/j.synthmet.2010.11.028"
- Description: This study investigates the synthesis and characterization new peripherally (β) tetra-substituted 4-(2-mercaptoquinoline phthalocyaninato) Co(II) (CoPcSHQn, 3), and 4-(2-phenoxy-4-trifluoromethylpyridine phthalocyaninato) Co(II) (CoPcOHPy, 4). These complexes were characterized by elemental analysis, IR, mass and electronic spectroscopies and electrochemical methods. Both complexes show well resolved redox peaks attributed to both ring and metal based processes. Spectroelectrochemistry was used to confirm the assignments of the redox processes. For CoPcSHQn (3): CoIPc−2/CoIPc−3 (E1/2 = −1.25 V, I), CoIIPc−2/CoIPc−2 (E1/2 = −0.57 V, II), CoIIIPc−2/CoIIPc−2 (E1/2 = +0.45 V, IV) and an irreversible process at Ep = +1.05 V vs Ag|AgCl for CoIIIPc−1/CoIIIPc−2 (V). Redox couple III at E1/2 = −0.15 V was ascribed to aggregation. In the case of CoPcOHPy (4): CoIPc−2/CoIPc−3 (E1/2 = −1.13 V, I), CoIIPc−2/CoIPc−2 (E1/2 = −0.45 V, II), CoIIIPc−2/CoIIPc−2 at E1/2 = +0.21 V (IV), and CoIIIPc−1/CoIIIPc−2 (E1/2 = +1.01 V vs Ag|AgCl, V). Again III is associated with the aggregated species. Both complexes were electrodeposited on a glassy carbon electrode (GCE). For complex 3 self-assembled monolayers was also formed. The modified (CoPc-GCE) electrodes electrocatalytically detected L-cysteine at Ep = 0.62 V (3-GCE) and 0.59 V (4-GCE) vs Ag|AgCl.
- Full Text:
- Date Issued: 2011
An evaluation of the feasibility of obtaining payment for ecosystem services for the Baviaanskloof Nature Reserve
- Authors: Erlank, Wayne Michael
- Date: 2011
- Subjects: Ecosystem services -- South Africa -- Eastern Cape Ecology -- Economic aspects -- South Africa -- Eastern Cape Environmental economics -- South Africa -- Eastern Cape Water-supply -- South Africa -- Eastern Cape Water-supply -- South Africa -- Eastern Cape -- Management Water resources development -- South Africa -- Eastern Cape Nature conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:742 , http://hdl.handle.net/10962/d1003862
- Description: Cities must go further and further away to find new, more costly sources of water for human consumption while industries and agriculture continue to compete for increasingly scarce water resources. This may already be seen occurring within the Nelson Mandela Bay Metro where the severe drought being experienced during the past 18 months has severely depleted water supply dams. One of the main supply dams to the Nelson Mandela Bay Municipality is situated within the Baviaanskloof Nature Reserve and World Heritage Site. The potential of funding the Baviaanskloof Nature Reserve and World Heritage Site with payments for ecosystem services (water) obtained for water services supplied to the Nelson Mandela Bay Municipalities and agriculture in the Gamtoos River Valley will ensure financial sustainable for the Baviaanskloof Nature Reserve and World Heritage Site in the long term. This ability to become financially independent and generate its own income will place the Baviaanskloof Nature Reserve and World Heritage Site in a unique position within the conservation community in South Africa as only a very few protected areas are self sustaining through payment for an ecosystem service.
- Full Text:
- Date Issued: 2011
- Authors: Erlank, Wayne Michael
- Date: 2011
- Subjects: Ecosystem services -- South Africa -- Eastern Cape Ecology -- Economic aspects -- South Africa -- Eastern Cape Environmental economics -- South Africa -- Eastern Cape Water-supply -- South Africa -- Eastern Cape Water-supply -- South Africa -- Eastern Cape -- Management Water resources development -- South Africa -- Eastern Cape Nature conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:742 , http://hdl.handle.net/10962/d1003862
- Description: Cities must go further and further away to find new, more costly sources of water for human consumption while industries and agriculture continue to compete for increasingly scarce water resources. This may already be seen occurring within the Nelson Mandela Bay Metro where the severe drought being experienced during the past 18 months has severely depleted water supply dams. One of the main supply dams to the Nelson Mandela Bay Municipality is situated within the Baviaanskloof Nature Reserve and World Heritage Site. The potential of funding the Baviaanskloof Nature Reserve and World Heritage Site with payments for ecosystem services (water) obtained for water services supplied to the Nelson Mandela Bay Municipalities and agriculture in the Gamtoos River Valley will ensure financial sustainable for the Baviaanskloof Nature Reserve and World Heritage Site in the long term. This ability to become financially independent and generate its own income will place the Baviaanskloof Nature Reserve and World Heritage Site in a unique position within the conservation community in South Africa as only a very few protected areas are self sustaining through payment for an ecosystem service.
- Full Text:
- Date Issued: 2011
South African money market volatility, asymmetry and retail interest pass-through
- Authors: Fadiran, Gideon Oluwatobi
- Date: 2011
- Subjects: Money market -- South Africa Interest rates -- South Africa Monetary policy -- South Africa Econometric models Banks and banking -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:993 , http://hdl.handle.net/10962/d1002728
- Description: The purpose of this paper is to examine the interest rate transmission mechanism for South Africa as an emerging economy in a pre-repo and repo system. It explains how the money market rate is transmitted to the retail interest rates both in the long-run and short-run and tests the symmetric and asymmetric interest rate pass-through using the Scholnick (1996) ECM and the Wang and Lee (2009) ECM-EGARCH (1, 1)-M methodology. This permitted the examination of the impact of interest rate volatility, along with the leverage effect. An incomplete pass-through is found in the short-run. From the entire sample period, a symmetric adjustment is found in the deposit rate, which had upward rigidity adjustment, while an asymmetric adjustment is found in the lending rate, with a downward rigidity adjustment. All the adjustments supported the collusive pricing arrangements. According to the conditional variance estimation of the ECM-EGARCH (1, 1), negative volatility impact and leverage effect are present and influential only in the deposit interest rate adjustment process in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Fadiran, Gideon Oluwatobi
- Date: 2011
- Subjects: Money market -- South Africa Interest rates -- South Africa Monetary policy -- South Africa Econometric models Banks and banking -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:993 , http://hdl.handle.net/10962/d1002728
- Description: The purpose of this paper is to examine the interest rate transmission mechanism for South Africa as an emerging economy in a pre-repo and repo system. It explains how the money market rate is transmitted to the retail interest rates both in the long-run and short-run and tests the symmetric and asymmetric interest rate pass-through using the Scholnick (1996) ECM and the Wang and Lee (2009) ECM-EGARCH (1, 1)-M methodology. This permitted the examination of the impact of interest rate volatility, along with the leverage effect. An incomplete pass-through is found in the short-run. From the entire sample period, a symmetric adjustment is found in the deposit rate, which had upward rigidity adjustment, while an asymmetric adjustment is found in the lending rate, with a downward rigidity adjustment. All the adjustments supported the collusive pricing arrangements. According to the conditional variance estimation of the ECM-EGARCH (1, 1), negative volatility impact and leverage effect are present and influential only in the deposit interest rate adjustment process in South Africa.
- Full Text:
- Date Issued: 2011
In vitro drug-herb interaction potential of African medicinal plant products used by Type II diabetics
- Authors: Fang, Yuan Yuan
- Date: 2011
- Subjects: Materia medica, Vegetable -- South Africa , Drugs -- Therapeutic use , Drug-herb interactions -- South Africa , Non-insulin-dependent diabetes -- South Africa , Non-insulin-dependent diabetes -- Treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10317 , http://hdl.handle.net/10948/1341 , Materia medica, Vegetable -- South Africa , Drugs -- Therapeutic use , Drug-herb interactions -- South Africa , Non-insulin-dependent diabetes -- South Africa , Non-insulin-dependent diabetes -- Treatment -- South Africa
- Description: In Africa, use of medicinal plants for the treatment of diabetes is very common. However, efficacy on co-administering of medicinal plants with therapeutic drugs hasn't been fully determined, especially for African medicinal plants. The current study focused on assessing the in vitro modulation effects of three popular African medicinal plants, namely: Aloe ferox, Sutherlandia frutescens and Prunus africana (including five commercial preparations containing these medicinal plants) on two of the most important anti-diabetic drug metabolising enzymes, Cytochrome P450 (CYP450) 2C9 and CYP3A4 and a key drug efflux transporter, P-glycoprotein (P-gp). Vivid® microsome-based screening kits were used to assess inhibitory potency of plants preparations on CYP2C9 and CYP3A4 enzymes activities. The study showed that P. africana was a more potent inhibitor of CYP2C9 and CYP3A4 activity than the corresponding positive controls Ginkgo biloba and St. John's wort, which are known to cause clinically significant drug-herb interactions. S. frutescens leaf extract demonstrated potent to moderate inhibition on both the tested CYP activities, while its commercial products (Promune® and Probetix®) possessed moderate to mild inhibitory effects on the activities of both CYPs. Potent inhibitory effect on CYP2C9 and CYP3A4 was seen with Aloe Ferox®. Prosit® and Aloes powder® showed potent to moderate inhibition on CYP2C9 activity and moderate to mild inhibition on CYP3A4 activity. In addition to CYP450 activity, the present study also investigated the effects of the selected medicinal plant products on the activity of the main drug efflux protein, P-gp. A screening assay was specifically developed to assess the potential for herbal remedies to interact with P-gp mediated drug absorption. The assay is based on the principle of the reversal of drug resistance in modified Caco-2 cells specifically altered to express high iv efflux protein activity. These cells display a multidrug resistance phenotype and the addition of a plant extract containing a P-gp inhibitor or substrate will inhibit or compete with any cytotoxic drug and consequently reverse the drug resistance. The suitability of the assay was confirmed using a known P-gp inhibitor. The study observed that the anti-proliferation effect of vinblastine was significantly enhanced in vinblastine-resistant Caco-2 cells, which have high P-gp expression, when they were exposed to the selected African herbal preparations. This observation indicates that the studied plant preparations may alter P-gp functionality and therefore lead to interference with the absorption of co-administered drugs. The outcomes of this study provide useful information on whether there are any potential drug-herb interactions between the commonly used African medicinal plants and oral anti-diabetic drugs, at the level of CYP and P-gp drug metabolism and could contribute to better therapeutic management of Type II diabetics. However these predicted interactions will need to be verified in a clinical setting.
- Full Text:
- Date Issued: 2011
- Authors: Fang, Yuan Yuan
- Date: 2011
- Subjects: Materia medica, Vegetable -- South Africa , Drugs -- Therapeutic use , Drug-herb interactions -- South Africa , Non-insulin-dependent diabetes -- South Africa , Non-insulin-dependent diabetes -- Treatment -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10317 , http://hdl.handle.net/10948/1341 , Materia medica, Vegetable -- South Africa , Drugs -- Therapeutic use , Drug-herb interactions -- South Africa , Non-insulin-dependent diabetes -- South Africa , Non-insulin-dependent diabetes -- Treatment -- South Africa
- Description: In Africa, use of medicinal plants for the treatment of diabetes is very common. However, efficacy on co-administering of medicinal plants with therapeutic drugs hasn't been fully determined, especially for African medicinal plants. The current study focused on assessing the in vitro modulation effects of three popular African medicinal plants, namely: Aloe ferox, Sutherlandia frutescens and Prunus africana (including five commercial preparations containing these medicinal plants) on two of the most important anti-diabetic drug metabolising enzymes, Cytochrome P450 (CYP450) 2C9 and CYP3A4 and a key drug efflux transporter, P-glycoprotein (P-gp). Vivid® microsome-based screening kits were used to assess inhibitory potency of plants preparations on CYP2C9 and CYP3A4 enzymes activities. The study showed that P. africana was a more potent inhibitor of CYP2C9 and CYP3A4 activity than the corresponding positive controls Ginkgo biloba and St. John's wort, which are known to cause clinically significant drug-herb interactions. S. frutescens leaf extract demonstrated potent to moderate inhibition on both the tested CYP activities, while its commercial products (Promune® and Probetix®) possessed moderate to mild inhibitory effects on the activities of both CYPs. Potent inhibitory effect on CYP2C9 and CYP3A4 was seen with Aloe Ferox®. Prosit® and Aloes powder® showed potent to moderate inhibition on CYP2C9 activity and moderate to mild inhibition on CYP3A4 activity. In addition to CYP450 activity, the present study also investigated the effects of the selected medicinal plant products on the activity of the main drug efflux protein, P-gp. A screening assay was specifically developed to assess the potential for herbal remedies to interact with P-gp mediated drug absorption. The assay is based on the principle of the reversal of drug resistance in modified Caco-2 cells specifically altered to express high iv efflux protein activity. These cells display a multidrug resistance phenotype and the addition of a plant extract containing a P-gp inhibitor or substrate will inhibit or compete with any cytotoxic drug and consequently reverse the drug resistance. The suitability of the assay was confirmed using a known P-gp inhibitor. The study observed that the anti-proliferation effect of vinblastine was significantly enhanced in vinblastine-resistant Caco-2 cells, which have high P-gp expression, when they were exposed to the selected African herbal preparations. This observation indicates that the studied plant preparations may alter P-gp functionality and therefore lead to interference with the absorption of co-administered drugs. The outcomes of this study provide useful information on whether there are any potential drug-herb interactions between the commonly used African medicinal plants and oral anti-diabetic drugs, at the level of CYP and P-gp drug metabolism and could contribute to better therapeutic management of Type II diabetics. However these predicted interactions will need to be verified in a clinical setting.
- Full Text:
- Date Issued: 2011
Development, manufacture and assessment of Clobetasol 17-propionate cream formulations
- Fauzee, Ayeshah Fateemah Beebee
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2011
- Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
- Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
- Full Text:
- Date Issued: 2011
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2011
- Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
- Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
- Full Text:
- Date Issued: 2011
The genetic diversity and conservation biology of the rare terrestrial snail genus Prestonella
- Authors: Fearon, Janine Lee
- Date: 2011
- Subjects: Snails -- South Africa , Snails -- Conservation -- South Africa , Snails -- Variation -- South Africa , Biodiversity -- South Africa , Snails -- Genetics -- South Africa , Snails -- Habitat -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4191 , http://hdl.handle.net/10962/d1003760 , Snails -- South Africa , Snails -- Conservation -- South Africa , Snails -- Variation -- South Africa , Biodiversity -- South Africa , Snails -- Genetics -- South Africa , Snails -- Habitat -- South Africa
- Description: Prestonella bowkeri and Prestonella nuptialis are montane specialists endemic to the southern Great Escarpment of South Africa. Phylogeographic analyses of these species based on mitochondrial markers CO1 and 16S reveal extremely high levels of divergence between populations indicating a lack of gene flow between populations. This is not surprising, because P. nuptialis and P. bowkeri have limited dispersal capacity, low vagility, a highly fragmented distribution and are habitat specialists that are restricted to isolated mesic refugia associated with waterfalls and montane seepages. A relaxed Bayesian clock estimate suggests that populations diverged from one another during the mid-late Miocene (12.5-7 MYA) which coincides with the modern trends of seasonal aridity which began during the Miocene. This result should be viewed with caution because the rates used are at best imprecise estimates of mutation rates in snails. There is no clear dichotomy between the two species and P. bowkeri is paraphyletic with respect to P. nuptialis, as a consequence the taxonomy is unclear. Due to the high levels of sequence divergence between populations they may be considered as evolutionary significant units (ESU’s). An assessment of haplotype diversity (h) and nucleotide diversity (π) reveals that populations in the western part of the Great Escarpment are more genetically depauperate than populations in the east. Correlations between genetic diversity and climatic variables show that genetically depauperate populations are found in areas that have lower annual rainfall, less reliable rainfall and higher potential evaporation, all factors associated with a drier, less mesic environment that increases the chances of a population bottleneck. This indicates that a shift towards a more arid environment may be a driver of genetic erosion. Historical climate change may thus have affected the amount and distribution of genetic diversity across the Great Escarpment since the Miocene. This has serious future implications for the survival of Prestonella. With predicted increase in global temperatures, climate change in South Africa is likely to result in range contraction and an eastward range shift for many species in the drier central and western areas (Erasmus et al. 2002) and regions along the Great Escarpment are likely to become more arid. Prestonella populations found living on inselbergs along the Great Escarpment are already restricted to site specific watercourses and seepages. An increase in the periods between stream flow, and increasing rainfall variability and mean annual potential evaporation are likely to have an adverse affect on species living in these habitats, resulting in further bottlenecks and possibly local extinction. An IUCN assessment of P. nuptialis and P. bowkeri suggests that these two species are probably endangered. The issue surrounding the conservation of Prestonella species is that they are threatened by global climate change, which cannot be simply restricted or prevented, which makes dealing with the threat of climate change difficult. Assisted migration (MA) may be considered as a method to prevent possible future extinctions of Prestonella populations, but will only be considered as a last resort. The thermal tolerance (Arrhenius breaking temperature and flat-line temperature) of individual snails from three Prestonella populations (one forest population and two thicket populations) were assessed using infrared sensors that detected changes in heart rate with increasing temperature. The forest population had a significantly lower Arrhenius breaking temperature (ABT) and flat-line temperature (FLT) than the two thicket population (p<0.05). Our results do not show a correlation between upper thermal limits and maximum habitat temperatures or other climatic variables in Prestonella populations. Although no correlation is found between ABT and maximum habitat temperature, it is likely that the differences seen between these populations are due to local micro-climate adaptation. The climatic variables used in this experiment are coarse estimates from GIS data and do not reflect actual microhabitat conditions. Forest environments are less heat stressed than thicket environments due to the forest canopy which may explain the lower ABT and FLT of the forest population.
- Full Text:
- Date Issued: 2011
- Authors: Fearon, Janine Lee
- Date: 2011
- Subjects: Snails -- South Africa , Snails -- Conservation -- South Africa , Snails -- Variation -- South Africa , Biodiversity -- South Africa , Snails -- Genetics -- South Africa , Snails -- Habitat -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4191 , http://hdl.handle.net/10962/d1003760 , Snails -- South Africa , Snails -- Conservation -- South Africa , Snails -- Variation -- South Africa , Biodiversity -- South Africa , Snails -- Genetics -- South Africa , Snails -- Habitat -- South Africa
- Description: Prestonella bowkeri and Prestonella nuptialis are montane specialists endemic to the southern Great Escarpment of South Africa. Phylogeographic analyses of these species based on mitochondrial markers CO1 and 16S reveal extremely high levels of divergence between populations indicating a lack of gene flow between populations. This is not surprising, because P. nuptialis and P. bowkeri have limited dispersal capacity, low vagility, a highly fragmented distribution and are habitat specialists that are restricted to isolated mesic refugia associated with waterfalls and montane seepages. A relaxed Bayesian clock estimate suggests that populations diverged from one another during the mid-late Miocene (12.5-7 MYA) which coincides with the modern trends of seasonal aridity which began during the Miocene. This result should be viewed with caution because the rates used are at best imprecise estimates of mutation rates in snails. There is no clear dichotomy between the two species and P. bowkeri is paraphyletic with respect to P. nuptialis, as a consequence the taxonomy is unclear. Due to the high levels of sequence divergence between populations they may be considered as evolutionary significant units (ESU’s). An assessment of haplotype diversity (h) and nucleotide diversity (π) reveals that populations in the western part of the Great Escarpment are more genetically depauperate than populations in the east. Correlations between genetic diversity and climatic variables show that genetically depauperate populations are found in areas that have lower annual rainfall, less reliable rainfall and higher potential evaporation, all factors associated with a drier, less mesic environment that increases the chances of a population bottleneck. This indicates that a shift towards a more arid environment may be a driver of genetic erosion. Historical climate change may thus have affected the amount and distribution of genetic diversity across the Great Escarpment since the Miocene. This has serious future implications for the survival of Prestonella. With predicted increase in global temperatures, climate change in South Africa is likely to result in range contraction and an eastward range shift for many species in the drier central and western areas (Erasmus et al. 2002) and regions along the Great Escarpment are likely to become more arid. Prestonella populations found living on inselbergs along the Great Escarpment are already restricted to site specific watercourses and seepages. An increase in the periods between stream flow, and increasing rainfall variability and mean annual potential evaporation are likely to have an adverse affect on species living in these habitats, resulting in further bottlenecks and possibly local extinction. An IUCN assessment of P. nuptialis and P. bowkeri suggests that these two species are probably endangered. The issue surrounding the conservation of Prestonella species is that they are threatened by global climate change, which cannot be simply restricted or prevented, which makes dealing with the threat of climate change difficult. Assisted migration (MA) may be considered as a method to prevent possible future extinctions of Prestonella populations, but will only be considered as a last resort. The thermal tolerance (Arrhenius breaking temperature and flat-line temperature) of individual snails from three Prestonella populations (one forest population and two thicket populations) were assessed using infrared sensors that detected changes in heart rate with increasing temperature. The forest population had a significantly lower Arrhenius breaking temperature (ABT) and flat-line temperature (FLT) than the two thicket population (p<0.05). Our results do not show a correlation between upper thermal limits and maximum habitat temperatures or other climatic variables in Prestonella populations. Although no correlation is found between ABT and maximum habitat temperature, it is likely that the differences seen between these populations are due to local micro-climate adaptation. The climatic variables used in this experiment are coarse estimates from GIS data and do not reflect actual microhabitat conditions. Forest environments are less heat stressed than thicket environments due to the forest canopy which may explain the lower ABT and FLT of the forest population.
- Full Text:
- Date Issued: 2011
Population assessments of priority plant species used by local communities in and around three Wild Coast reserves, Eastern Cape, South Africa
- Authors: Fearon, Joclyn Joe
- Date: 2011
- Subjects: Plant diversity conservation -- South Africa -- Eastern Cape , Rare plants -- South Africa -- Eastern Cape -- Population viability analysis , Biodiversity -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa -- Eastern Cape , Human-plant relationships -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4751 , http://hdl.handle.net/10962/d1007059 , Plant diversity conservation -- South Africa -- Eastern Cape , Rare plants -- South Africa -- Eastern Cape -- Population viability analysis , Biodiversity -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa -- Eastern Cape , Human-plant relationships -- South Africa -- Eastern Cape
- Description: The project was initiated by Eastern Cape Parks (ECP) as a request for the construction of inventories of priority species and their population levels inside three nature reserves on the Eastern Cape Wild Coast, South Africa, and to develop a strategic management plan to manage these natural resources in each reserve. Thirty key species were identified by local communities in and around Dwesa-Cwebe, Silaka and Mkambati Nature Reserves through community workshops. For forested areas belt transects of 100 m x 6 m where used. The basal circumference of key tree species within the belt transect was measured as well as the height of saplings (height < 150 m). Tree species were categorized based on densities, size class distribution (SCD) curves and values, and spatial grain. For grassland areas straight transects of 200 m long were used, along which ten 3 m x 3 m quadrates were placed at 20 m intervals. Within each grassland transect the height of herbs or tuft diameter of grasses was recorded and percentage cover estimated. Grassland species were categorized based on density, SCD curves and percentage cover. All species were placed into harvesting categories based on analysed ecological data that was collected in the field. Category 1 species were very rare or not found in the reserve and it was recommended that species be conserved and monitored. Category 2 species had low densities in the reserve indicating declining populations and was suggested that these be monitored and not harvested. Category 3 species had high densities and have potential for harvesting with strict limitations. Category 4 species were most abundant with very high densities and can be harvested within management guidelines. These categories were grouped further using social and ecological data such as harvesting risk, frequency of collection, use value and number of uses. This highlighted which species have conservation priority within each category and a decision can be made as to how intense or limited extraction should be. By incorporating GIS the distribution of each species was looked at and harvesting and non-harvesting zones established to determine where species can be extracted. Monitoring plans must consider the quantity of plant material collected, fire regimes, optimal harvesting rates and harvesting zones, and be able to pick up changes in populations. Also, it is important that the community be involved in conserving and monitoring these species. Adaptive monitoring and management must be used to steer harvesting practices in the Wild Coast reserves. This allows for the development of harvesting practices through ‘learning by doing’, and the evolution of good questions to guide monitoring decisions
- Full Text:
- Date Issued: 2011
- Authors: Fearon, Joclyn Joe
- Date: 2011
- Subjects: Plant diversity conservation -- South Africa -- Eastern Cape , Rare plants -- South Africa -- Eastern Cape -- Population viability analysis , Biodiversity -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa -- Eastern Cape , Human-plant relationships -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4751 , http://hdl.handle.net/10962/d1007059 , Plant diversity conservation -- South Africa -- Eastern Cape , Rare plants -- South Africa -- Eastern Cape -- Population viability analysis , Biodiversity -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa -- Eastern Cape , Human-plant relationships -- South Africa -- Eastern Cape
- Description: The project was initiated by Eastern Cape Parks (ECP) as a request for the construction of inventories of priority species and their population levels inside three nature reserves on the Eastern Cape Wild Coast, South Africa, and to develop a strategic management plan to manage these natural resources in each reserve. Thirty key species were identified by local communities in and around Dwesa-Cwebe, Silaka and Mkambati Nature Reserves through community workshops. For forested areas belt transects of 100 m x 6 m where used. The basal circumference of key tree species within the belt transect was measured as well as the height of saplings (height < 150 m). Tree species were categorized based on densities, size class distribution (SCD) curves and values, and spatial grain. For grassland areas straight transects of 200 m long were used, along which ten 3 m x 3 m quadrates were placed at 20 m intervals. Within each grassland transect the height of herbs or tuft diameter of grasses was recorded and percentage cover estimated. Grassland species were categorized based on density, SCD curves and percentage cover. All species were placed into harvesting categories based on analysed ecological data that was collected in the field. Category 1 species were very rare or not found in the reserve and it was recommended that species be conserved and monitored. Category 2 species had low densities in the reserve indicating declining populations and was suggested that these be monitored and not harvested. Category 3 species had high densities and have potential for harvesting with strict limitations. Category 4 species were most abundant with very high densities and can be harvested within management guidelines. These categories were grouped further using social and ecological data such as harvesting risk, frequency of collection, use value and number of uses. This highlighted which species have conservation priority within each category and a decision can be made as to how intense or limited extraction should be. By incorporating GIS the distribution of each species was looked at and harvesting and non-harvesting zones established to determine where species can be extracted. Monitoring plans must consider the quantity of plant material collected, fire regimes, optimal harvesting rates and harvesting zones, and be able to pick up changes in populations. Also, it is important that the community be involved in conserving and monitoring these species. Adaptive monitoring and management must be used to steer harvesting practices in the Wild Coast reserves. This allows for the development of harvesting practices through ‘learning by doing’, and the evolution of good questions to guide monitoring decisions
- Full Text:
- Date Issued: 2011
Customer relationship management practiced by KOSAB
- Authors: Felix, Amoah
- Date: 2011
- Subjects: Customer relations , Customer services , Consumer satisfaction , Customer loyalty
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:8635 , http://hdl.handle.net/10948/d1008046 , Customer relations , Customer services , Consumer satisfaction , Customer loyalty
- Description: Customer relationship management (CRM) presents a new paradigm shift to the old traditional marketing strategies that are known and practiced by many organisations in South Africa and across the globe. Competition is not an excuse for failure anymore. Organisations that do not have any concrete strategies in dealing with the customer will not survive in the market. The ultimate goal of CRM is to enable organisations to forge closer ties with the customer so that a solid bond can be created to enhance loyalty and satisfaction. The goal for this research was to identify the CRM strategies used by a single organisation and thereafter suggest improvements to enhance customer loyalty. The results of the study could assist the management of the organisation to improve the CRM strategies which will hopefully enhance retention and prevent customer attrition. A literature review was conducted to unveil various elements of CRM, and strategies that can attract and retain customers. It helped in identifying themes for the empirical study. An in-depth interview was conducted with the general manager of the organisation to gauge his perception, and CRM practices in the organisation. An interview guide was used during the interview process. Four main topics namely: implementation of CRM, customer loyalty, customer complaints and conflict, and employees training and motivation were utilised for the interview guide and followed by further probing. Based on the responses obtained, analyses were made by comparing the responses to what literature revealed so that shortcomings could easily be identified.The study revealed that there were several inconsistencies with what was practised by the organisation and what the literature study revealed. Bearing in mind the shortcomings identified in the empirical study, the researcher made the following recommendations. The CRM implementation approach needs to be carefully planned with a clear defined vision and mission statement that focus on customer centredness. The organisation needs to invest in modern and innovative channels of communication and strategic partnership to reach the right customer. The organisation has to develop effective market segmentation and targeting to know the customer well. Consistent and highly relevant customer experiences should be drawn-on to fulfill the organisation’s promise of trust and reliability. The organisation should adopt competitive pricing strategy to limit customer sensitivity on price. The organisation should invest in employees’ development and welfare. Further research can be conducted to investigate the perception of other food retailers on the CRM strategies practiced. Further research can also be conducted in the organisation to investigate the perception of employees and customers on the CRM strategies practised.
- Full Text:
- Date Issued: 2011
- Authors: Felix, Amoah
- Date: 2011
- Subjects: Customer relations , Customer services , Consumer satisfaction , Customer loyalty
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:8635 , http://hdl.handle.net/10948/d1008046 , Customer relations , Customer services , Consumer satisfaction , Customer loyalty
- Description: Customer relationship management (CRM) presents a new paradigm shift to the old traditional marketing strategies that are known and practiced by many organisations in South Africa and across the globe. Competition is not an excuse for failure anymore. Organisations that do not have any concrete strategies in dealing with the customer will not survive in the market. The ultimate goal of CRM is to enable organisations to forge closer ties with the customer so that a solid bond can be created to enhance loyalty and satisfaction. The goal for this research was to identify the CRM strategies used by a single organisation and thereafter suggest improvements to enhance customer loyalty. The results of the study could assist the management of the organisation to improve the CRM strategies which will hopefully enhance retention and prevent customer attrition. A literature review was conducted to unveil various elements of CRM, and strategies that can attract and retain customers. It helped in identifying themes for the empirical study. An in-depth interview was conducted with the general manager of the organisation to gauge his perception, and CRM practices in the organisation. An interview guide was used during the interview process. Four main topics namely: implementation of CRM, customer loyalty, customer complaints and conflict, and employees training and motivation were utilised for the interview guide and followed by further probing. Based on the responses obtained, analyses were made by comparing the responses to what literature revealed so that shortcomings could easily be identified.The study revealed that there were several inconsistencies with what was practised by the organisation and what the literature study revealed. Bearing in mind the shortcomings identified in the empirical study, the researcher made the following recommendations. The CRM implementation approach needs to be carefully planned with a clear defined vision and mission statement that focus on customer centredness. The organisation needs to invest in modern and innovative channels of communication and strategic partnership to reach the right customer. The organisation has to develop effective market segmentation and targeting to know the customer well. Consistent and highly relevant customer experiences should be drawn-on to fulfill the organisation’s promise of trust and reliability. The organisation should adopt competitive pricing strategy to limit customer sensitivity on price. The organisation should invest in employees’ development and welfare. Further research can be conducted to investigate the perception of other food retailers on the CRM strategies practiced. Further research can also be conducted in the organisation to investigate the perception of employees and customers on the CRM strategies practised.
- Full Text:
- Date Issued: 2011
The demography and population dynamics of a re-introduced black rhinoceros population on the Great Fish River Reserve, Eastern Cape Province
- Authors: Fike, Bradley Robin
- Date: 2011
- Subjects: Black rhinoceros -- South Africa -- Great Fish River Valley , Population biology -- South Africa -- Great Fish River Valley , Black rhinoceros -- Habitat -- South Africa -- Great Fish River Valley , Black rhinoceros -- Adaptation -- South Africa -- Great Fish River Valley , Black rhinoceros -- Ecology -- South Africa -- Great Fish River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5948 , http://hdl.handle.net/10962/d1020869
- Description: The re-introduction of black rhinoceros onto the Great Fish River Reserve in the Eastern Cape, following the species absence for over a century, created an opportunity to study this species in the thicket biome, and in particular the succulent thicket of the Great Fish River valley. The thicket biome is quite different from the habitats in which other extant populations of these animals are found and where studies of their demography have been undertaken. Data collection occurred from May 1986, with the arrival of the first four animals to December 2008, when the population was estimated to be 144 individuals. A variety of monitoring techniques were used including direct ground observations, aerial helicopter census, aerial monitoring by microlight aircraft, camera traps and opportunistic observations, each with its own advantages and disadvantages. The combination of methods and effort has resulted in the population being recognized as completely known with up to 97% of the animals being located at least once per year with a mean frequency of sightings of 11.5 per animal per year. In 2008, the population was about 20% juvenile, 36% sub-adult and 44% adult with a female biased sex ratio of 1.3 females per male. Mean age at first birth was about 80 months and this increased significantly with increasing density of black rhinoceroses. Mean intercalf interval was about 28 months and 41% of adult females gave birth each year. Mortality rates were low for juveniles, higher for sub-adults and higher for males than females. There was a weak but significant positive effect of density on male mortality. Population growth rate was about 10% and was not significantly affected by density. These results suggest that this population is beginning to show the first indications of density dependant constraints and that harvesting should be implemented in order to maintain the productive tempo. A secondary goal of the Management Plan will then be realized as the population functions as a donor to establish founder populations elsewhere within the Diceros bicornis minor range.
- Full Text:
- Date Issued: 2011
- Authors: Fike, Bradley Robin
- Date: 2011
- Subjects: Black rhinoceros -- South Africa -- Great Fish River Valley , Population biology -- South Africa -- Great Fish River Valley , Black rhinoceros -- Habitat -- South Africa -- Great Fish River Valley , Black rhinoceros -- Adaptation -- South Africa -- Great Fish River Valley , Black rhinoceros -- Ecology -- South Africa -- Great Fish River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5948 , http://hdl.handle.net/10962/d1020869
- Description: The re-introduction of black rhinoceros onto the Great Fish River Reserve in the Eastern Cape, following the species absence for over a century, created an opportunity to study this species in the thicket biome, and in particular the succulent thicket of the Great Fish River valley. The thicket biome is quite different from the habitats in which other extant populations of these animals are found and where studies of their demography have been undertaken. Data collection occurred from May 1986, with the arrival of the first four animals to December 2008, when the population was estimated to be 144 individuals. A variety of monitoring techniques were used including direct ground observations, aerial helicopter census, aerial monitoring by microlight aircraft, camera traps and opportunistic observations, each with its own advantages and disadvantages. The combination of methods and effort has resulted in the population being recognized as completely known with up to 97% of the animals being located at least once per year with a mean frequency of sightings of 11.5 per animal per year. In 2008, the population was about 20% juvenile, 36% sub-adult and 44% adult with a female biased sex ratio of 1.3 females per male. Mean age at first birth was about 80 months and this increased significantly with increasing density of black rhinoceroses. Mean intercalf interval was about 28 months and 41% of adult females gave birth each year. Mortality rates were low for juveniles, higher for sub-adults and higher for males than females. There was a weak but significant positive effect of density on male mortality. Population growth rate was about 10% and was not significantly affected by density. These results suggest that this population is beginning to show the first indications of density dependant constraints and that harvesting should be implemented in order to maintain the productive tempo. A secondary goal of the Management Plan will then be realized as the population functions as a donor to establish founder populations elsewhere within the Diceros bicornis minor range.
- Full Text:
- Date Issued: 2011
Modelling trends in evapotranspiration using the MODIS LAI for selected Eastern Cape catchments
- Authors: Finca, Andiswa
- Date: 2011
- Subjects: Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10651 , http://hdl.handle.net/10948/d1009517 , Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Description: Grassland is the dominant vegetation cover of many of the 19 Water Catchment Areas within South Africa. The inappropriate management of some of these grassland catchments by the communities that depend on them for their livelihoods, often results in overgrazed lands with low biomass or invasive alien species. The short grass maintained by grazing policies of many communities results in high storm flows that have an adverse effect on the quantity and quality of runoff and recharge. Catchment-scale water balances depend on accurate estimates of run-off, recharge and evapotranspiration (ET). This study focuses on the ET component of the catchment scale water balance and explores the effect of two different grazing strategies on ET. To achieve this, two contrasting but adjacent quaternary catchments namely: P10A (a high biomass site) and Q91C (a low biomass site) were selected within the Bushman’s River Primary catchment as primary study sites. Within each catchment, a relatively homogenous pixel of 1 km was selected, representing contrasting example of high and low intensity grazing. From an eleven year MODIS leaf area index (LAI) data stack (March 2000 – 2010), 8-day LAI values was extracted for each pixel in each catchment. Using the Penman- Monteith equation, potential evapotranspiration (ET0) was calculated using data from a nearly automatic weather station. Actual evapotranspiration was estimated by adjusting ET0 using the values extracted from the MODIS LAI product. The MODIS LAI ET (ETMODIS) obtained for the eleven year period for both 1 km pixels decreased consistently, reflecting a general trend in declining LAI throughout the Eastern Cape. The highest ETMODIS obtained from P10A was 610.3 mm (2001) and the lowest was 333.1 mm (2009). Then from Q91C the highest ET obtained was 534.7 mm (2006) and the lowest was 266.2 mm (2009). The ETMODIS results were validated for each catchment using the Open Top Chamber (OTC) which sums the water lost from vegetation and soil within the chamber. This validation was conducted during the growing season of 2010–11. Wind speed; relative humidity and temperature were measured both at the inlet and the outlet of the chamber on five clear sunny days for each 1 km pixel. ETa for the same period was compared to the OTC ET (ETOTC) using the regression analysis and a good relationship was observed with the r2 of 0.7065. The relationship observed confirmed that ETOTC closely approximates ETMODIS and that the OTC can be used as a tool to validate MODIS LAI ET on clear, low winds and sunny days. In order to demonstrate proof-of-concept for the use of this modeling of ETMODIS within a Payment for Ecosystem Services framework, the approach was applied to two other quaternary catchments under communal tenure. Within each catchment, three land use scenarios were created for each catchment to reflect potential changes in the standing aboveground biomass. For Scenario 1, the status quo was maintained; for Scenario 2, MODIS pixels representing 28 km in each catchment were selected and the LAI of these pixels was doubled; and for scenario 3, LAI was halved. ETMODIS was calculated for each scenario by adjusting the ET0 data from a nearby automatic weather station with the MODIS LAI product. The results showed that the estimated annual ETMODIS obtained from the high biomass catchment was 111 mm greater than that obtained from the low biomass catchment. When comparing between the scenarios, the annual ETMODIS obtained from scenario 2 was the highest of the 3 scenarios for both sites. These results confirm that increased leaf area results in higher annual ETMODIS. This has a positive long term impact on stream flow, as high grass biomass allows the rainfall to infiltrate the soil and be gradually released to the dams with reduced magnitude of storm flows. This approach has the potential to quantify the benefits to down-stream water users of improving above-ground biomass in catchments.
- Full Text:
- Date Issued: 2011
- Authors: Finca, Andiswa
- Date: 2011
- Subjects: Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10651 , http://hdl.handle.net/10948/d1009517 , Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Description: Grassland is the dominant vegetation cover of many of the 19 Water Catchment Areas within South Africa. The inappropriate management of some of these grassland catchments by the communities that depend on them for their livelihoods, often results in overgrazed lands with low biomass or invasive alien species. The short grass maintained by grazing policies of many communities results in high storm flows that have an adverse effect on the quantity and quality of runoff and recharge. Catchment-scale water balances depend on accurate estimates of run-off, recharge and evapotranspiration (ET). This study focuses on the ET component of the catchment scale water balance and explores the effect of two different grazing strategies on ET. To achieve this, two contrasting but adjacent quaternary catchments namely: P10A (a high biomass site) and Q91C (a low biomass site) were selected within the Bushman’s River Primary catchment as primary study sites. Within each catchment, a relatively homogenous pixel of 1 km was selected, representing contrasting example of high and low intensity grazing. From an eleven year MODIS leaf area index (LAI) data stack (March 2000 – 2010), 8-day LAI values was extracted for each pixel in each catchment. Using the Penman- Monteith equation, potential evapotranspiration (ET0) was calculated using data from a nearly automatic weather station. Actual evapotranspiration was estimated by adjusting ET0 using the values extracted from the MODIS LAI product. The MODIS LAI ET (ETMODIS) obtained for the eleven year period for both 1 km pixels decreased consistently, reflecting a general trend in declining LAI throughout the Eastern Cape. The highest ETMODIS obtained from P10A was 610.3 mm (2001) and the lowest was 333.1 mm (2009). Then from Q91C the highest ET obtained was 534.7 mm (2006) and the lowest was 266.2 mm (2009). The ETMODIS results were validated for each catchment using the Open Top Chamber (OTC) which sums the water lost from vegetation and soil within the chamber. This validation was conducted during the growing season of 2010–11. Wind speed; relative humidity and temperature were measured both at the inlet and the outlet of the chamber on five clear sunny days for each 1 km pixel. ETa for the same period was compared to the OTC ET (ETOTC) using the regression analysis and a good relationship was observed with the r2 of 0.7065. The relationship observed confirmed that ETOTC closely approximates ETMODIS and that the OTC can be used as a tool to validate MODIS LAI ET on clear, low winds and sunny days. In order to demonstrate proof-of-concept for the use of this modeling of ETMODIS within a Payment for Ecosystem Services framework, the approach was applied to two other quaternary catchments under communal tenure. Within each catchment, three land use scenarios were created for each catchment to reflect potential changes in the standing aboveground biomass. For Scenario 1, the status quo was maintained; for Scenario 2, MODIS pixels representing 28 km in each catchment were selected and the LAI of these pixels was doubled; and for scenario 3, LAI was halved. ETMODIS was calculated for each scenario by adjusting the ET0 data from a nearby automatic weather station with the MODIS LAI product. The results showed that the estimated annual ETMODIS obtained from the high biomass catchment was 111 mm greater than that obtained from the low biomass catchment. When comparing between the scenarios, the annual ETMODIS obtained from scenario 2 was the highest of the 3 scenarios for both sites. These results confirm that increased leaf area results in higher annual ETMODIS. This has a positive long term impact on stream flow, as high grass biomass allows the rainfall to infiltrate the soil and be gradually released to the dams with reduced magnitude of storm flows. This approach has the potential to quantify the benefits to down-stream water users of improving above-ground biomass in catchments.
- Full Text:
- Date Issued: 2011
An investigation into the impact of online and mobile advertising on the South African advertising landscape
- Authors: Flanagan, Michael Anthony
- Date: 2011
- Subjects: Internet advertising -- South Africa , Advertising -- South Africa , Electronic commerce -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8388 , http://hdl.handle.net/10948/d1008588 , Internet advertising -- South Africa , Advertising -- South Africa , Electronic commerce -- South Africa
- Description: This study aimed to provide South African advertising professionals with insights into the current state of online and mobile advertising in South Africa, highlighting areas in which this sector of the industry can develop in order for professionals to perpetuate successful and innovative use of the mediums available to them and their clients. The study draws on literature from the fields of traditional advertising, digital advertising and new media. Research on the South African digital advertising climate is not as readily available as that of international studies based in the United States of America and the United Kingdom. The study therefore used two data collection methods namely, telephonic semi-structured interviews with advertising professionals employed within the South African advertising and marketing industries as well as an electronic survey also aimed at advertising professionals employed within the South African advertising and marketing industries. The data collected aims to provide an insight into the professional opinions and feelings of these professionals as to how the South Africa digital advertising landscape is perceived, how it compares to its international counterparts and whether online and mobile technologies have had an impact on the South African advertising industry in terms of ad-spend not only on digital but on traditional advertising. The data from both the semi-structured interviews and survey were analysed in terms of the aforementioned aspects and correlations were found between the qualitative and quantitative data. Five advertising professionals from various agencies from around South Africa were interviewed telephonically while 27 advertising professionals attempted the electronic survey with 21 completing the survey. The study found that advertisers acknowledge that online and mobile technologies have had an impact on the South African advertising industry as digital advertising is now seen as an important fixture within the advertising industry and is considered to now be as important as traditional advertising. However, although advertising professionals acknowledge this importance, the medium is still underutilised due to a number of determining factors. These factors include insufficient knowledge in the field of digital advertising by advertisers and clients as clients are still unwilling to allocate similar levels of ad-spend to digital as they would to traditional advertising, this despite a notable increase in digital ad-spend. Traditional advertising still dominates ad-spend and advertisers are of the opinion that despite the growth of digital media, this trend will remain prevalent in South Africa which continues to trail behind its international counterparts.
- Full Text:
- Date Issued: 2011
- Authors: Flanagan, Michael Anthony
- Date: 2011
- Subjects: Internet advertising -- South Africa , Advertising -- South Africa , Electronic commerce -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8388 , http://hdl.handle.net/10948/d1008588 , Internet advertising -- South Africa , Advertising -- South Africa , Electronic commerce -- South Africa
- Description: This study aimed to provide South African advertising professionals with insights into the current state of online and mobile advertising in South Africa, highlighting areas in which this sector of the industry can develop in order for professionals to perpetuate successful and innovative use of the mediums available to them and their clients. The study draws on literature from the fields of traditional advertising, digital advertising and new media. Research on the South African digital advertising climate is not as readily available as that of international studies based in the United States of America and the United Kingdom. The study therefore used two data collection methods namely, telephonic semi-structured interviews with advertising professionals employed within the South African advertising and marketing industries as well as an electronic survey also aimed at advertising professionals employed within the South African advertising and marketing industries. The data collected aims to provide an insight into the professional opinions and feelings of these professionals as to how the South Africa digital advertising landscape is perceived, how it compares to its international counterparts and whether online and mobile technologies have had an impact on the South African advertising industry in terms of ad-spend not only on digital but on traditional advertising. The data from both the semi-structured interviews and survey were analysed in terms of the aforementioned aspects and correlations were found between the qualitative and quantitative data. Five advertising professionals from various agencies from around South Africa were interviewed telephonically while 27 advertising professionals attempted the electronic survey with 21 completing the survey. The study found that advertisers acknowledge that online and mobile technologies have had an impact on the South African advertising industry as digital advertising is now seen as an important fixture within the advertising industry and is considered to now be as important as traditional advertising. However, although advertising professionals acknowledge this importance, the medium is still underutilised due to a number of determining factors. These factors include insufficient knowledge in the field of digital advertising by advertisers and clients as clients are still unwilling to allocate similar levels of ad-spend to digital as they would to traditional advertising, this despite a notable increase in digital ad-spend. Traditional advertising still dominates ad-spend and advertisers are of the opinion that despite the growth of digital media, this trend will remain prevalent in South Africa which continues to trail behind its international counterparts.
- Full Text:
- Date Issued: 2011
Application of catalysts and nanomaterials in the design of an electrochemical sensor for ochratoxin A
- Authors: Flanagan, Shane Patrick
- Date: 2011 , 2010-12-06
- Subjects: Ochratoxins , Filamentous fungi , Electrochemical sensors , Nanostructured materials , Catalysts , Food contamination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4121 , http://hdl.handle.net/10962/d1013328
- Description: Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
- Full Text:
- Date Issued: 2011
- Authors: Flanagan, Shane Patrick
- Date: 2011 , 2010-12-06
- Subjects: Ochratoxins , Filamentous fungi , Electrochemical sensors , Nanostructured materials , Catalysts , Food contamination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4121 , http://hdl.handle.net/10962/d1013328
- Description: Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
- Full Text:
- Date Issued: 2011
Fundamental investigations into the factors affecting the response of laccase-based electrochemical biosensors
- Authors: Fogel, Ronen
- Date: 2011
- Subjects: Laccase Phenols Biosensors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4073 , http://hdl.handle.net/10962/d1007166
- Description: Given their widespread effects and distribution in both natural and industrial environments, the monitoring of phenolic compounds is of considerable analytical interest. Electrochemical biosensor technologies, in particular those comprising laccase enzymes, afford many potential benefits to address this analytical need. However, several key factors affecting sensor response currently limit their applicability. This Thesis reports on the fabrication and optimisation of an electrochemical laccase-based biosensor towards the application of the monitoring of phenolic compounds. Selected factors considered to affect sensor response were investigated using the optimised biosensor. These included: electrochemical, biochemical and substrate-dependent factors, which were found to intersect in modulating biosensor response signals. Through the application of transducer-dependent and substrate-dependent parameters, the selective and simultaneous detection of a mixture of different phenolic analytes is successfully demonstrated. This Thesis also investigates the use of Quartz-Crystal Microbalance with Dissipation (QCM-D) technology, an analytical technique that measures physical parameters of thin-film structures, towards the successful monitoring of enzyme immobilisation strategies. These strategies are fundamental to the successful fabrication of biosensors, and the real-time monitoring of immobilised film formations is of considerable research interest. In the studies reported on in this Thesis, QCM-D technology was demonstrated to be an effective complementary technology in the prediction of film immobilisation techniques on the resultant biochemical kinetics of immobilised enzymes.
- Full Text:
- Date Issued: 2011
- Authors: Fogel, Ronen
- Date: 2011
- Subjects: Laccase Phenols Biosensors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4073 , http://hdl.handle.net/10962/d1007166
- Description: Given their widespread effects and distribution in both natural and industrial environments, the monitoring of phenolic compounds is of considerable analytical interest. Electrochemical biosensor technologies, in particular those comprising laccase enzymes, afford many potential benefits to address this analytical need. However, several key factors affecting sensor response currently limit their applicability. This Thesis reports on the fabrication and optimisation of an electrochemical laccase-based biosensor towards the application of the monitoring of phenolic compounds. Selected factors considered to affect sensor response were investigated using the optimised biosensor. These included: electrochemical, biochemical and substrate-dependent factors, which were found to intersect in modulating biosensor response signals. Through the application of transducer-dependent and substrate-dependent parameters, the selective and simultaneous detection of a mixture of different phenolic analytes is successfully demonstrated. This Thesis also investigates the use of Quartz-Crystal Microbalance with Dissipation (QCM-D) technology, an analytical technique that measures physical parameters of thin-film structures, towards the successful monitoring of enzyme immobilisation strategies. These strategies are fundamental to the successful fabrication of biosensors, and the real-time monitoring of immobilised film formations is of considerable research interest. In the studies reported on in this Thesis, QCM-D technology was demonstrated to be an effective complementary technology in the prediction of film immobilisation techniques on the resultant biochemical kinetics of immobilised enzymes.
- Full Text:
- Date Issued: 2011
Heroes at the gates appeal and value in the Homeric epics from the archaic through the classical period
- Authors: Fox, Peta Ann
- Date: 2011
- Subjects: Homer. Iliad Homer. Odyssey Homer Criticism and interpretation Homer Influence Epic poetry, Greek -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3593 , http://hdl.handle.net/10962/d1002168
- Description: This thesis raises and explores questions concerning the popularity of the Homeric poems in ancient Greece. It asks why the Iliad and Odyssey held such continuing appeal among the Greeks of the Archaic and Classical age. Cultural products such as poetry cannot be separated from the sociopolitical conditions in which and for which they were originally composed and received. Working on the basis that the extent of Homer’s appeal was inspired and sustained by the peculiar and determining historical circumstances, I set out to explore the relation of the social, political and ethical conditions and values of Archaic and Classical Greece to those portrayed in the Homeric poems. The Greeks, at the time during which Homer was composing his poems, had begun to establish a new form of social organisation: the polis. By examining historical, literary and philosophical texts from the Archaic and Classical age, I explore the manner in which Greek society attempted to reorganise and reconstitute itself in a different way, developing original modes of social and political activity which the new needs and goals of their new social reality demanded. I then turn to examine Homer’s treatment of and response to this social context, and explore the various ways in which Homer was able to reinterpret and reinvent the inherited stories of adventure and warfare in order to compose poetry that not only looks back to the highly centralised and bureaucratic society of the Mycenaean world, but also looks forward, insistently so, to the urban reality of the present. I argue that Homer’s conflation of a remembered mythical age with the contemporary conditions and values of Archaic and Classical Greece aroused in his audiences a new perception and understanding of human existence in the altered sociopolitical conditions of the polis and, in so doing, ultimately contributed to the development of new ideas on the manner in which the Greeks could best live together in their new social world.
- Full Text:
- Date Issued: 2011
- Authors: Fox, Peta Ann
- Date: 2011
- Subjects: Homer. Iliad Homer. Odyssey Homer Criticism and interpretation Homer Influence Epic poetry, Greek -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3593 , http://hdl.handle.net/10962/d1002168
- Description: This thesis raises and explores questions concerning the popularity of the Homeric poems in ancient Greece. It asks why the Iliad and Odyssey held such continuing appeal among the Greeks of the Archaic and Classical age. Cultural products such as poetry cannot be separated from the sociopolitical conditions in which and for which they were originally composed and received. Working on the basis that the extent of Homer’s appeal was inspired and sustained by the peculiar and determining historical circumstances, I set out to explore the relation of the social, political and ethical conditions and values of Archaic and Classical Greece to those portrayed in the Homeric poems. The Greeks, at the time during which Homer was composing his poems, had begun to establish a new form of social organisation: the polis. By examining historical, literary and philosophical texts from the Archaic and Classical age, I explore the manner in which Greek society attempted to reorganise and reconstitute itself in a different way, developing original modes of social and political activity which the new needs and goals of their new social reality demanded. I then turn to examine Homer’s treatment of and response to this social context, and explore the various ways in which Homer was able to reinterpret and reinvent the inherited stories of adventure and warfare in order to compose poetry that not only looks back to the highly centralised and bureaucratic society of the Mycenaean world, but also looks forward, insistently so, to the urban reality of the present. I argue that Homer’s conflation of a remembered mythical age with the contemporary conditions and values of Archaic and Classical Greece aroused in his audiences a new perception and understanding of human existence in the altered sociopolitical conditions of the polis and, in so doing, ultimately contributed to the development of new ideas on the manner in which the Greeks could best live together in their new social world.
- Full Text:
- Date Issued: 2011
The photodecomposition of different polymorphic forms of 1,4-dihydropyridine channel blockers
- Authors: Francis, Farzaana
- Date: 2011
- Subjects: Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10378 , http://hdl.handle.net/10948/1496 , Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Description: 1,4-Dihydropyridines (DHPs) are a classification of compounds used as calcium channel blockers in the treatment of various conditions. These compounds readily undergo photodegradation. The degradants produced have no pharmaceutical activity and render the drugs ineffective. DHPs also exhibit polymorphism. Nifedipine and Nimodipine are two such drugs. This study aimed to monitor the photodegradation of these two drugs and to establish the effect of particle size, polymorphism and β-Cyclodextrin (β-CD) on the rate of photodegradation. Different polymorphs (namely the amorphous and stable crystalline polymorphs) of the two drugs were prepared for use in the study. Mixtures of each drug with β-CD were also prepared for photostability studies. The mixtures were prepared in a 1:1 molar ratio. The rate of photodegradation was studied with a 500 W metal halide lamp in accordance to ICH guidelines. The study employed samples on a small scale where degradation was analysed with High Performance Liquid Chromatography, and also samples on a larger scale where degradation was monitored with Powder X-ray Diffraction. The two sets of results of observing the degradation process by two analytical techniques where compared in terms of their quantification methods. The extent of photodegradation was suitably modelled and fitted using the Avrami-Erofeyev kinetic equation. Smaller particle size showed increased photodegradation for Nimodipine; the effect was insignificant for Nifedipine however. For both drugs it was found that the amorphous polymorph underwent faster photodegradation. The study showed that β-CD caused an increase in photodegradation for both drugs under these experimental conditions.
- Full Text:
- Date Issued: 2011
- Authors: Francis, Farzaana
- Date: 2011
- Subjects: Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10378 , http://hdl.handle.net/10948/1496 , Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Description: 1,4-Dihydropyridines (DHPs) are a classification of compounds used as calcium channel blockers in the treatment of various conditions. These compounds readily undergo photodegradation. The degradants produced have no pharmaceutical activity and render the drugs ineffective. DHPs also exhibit polymorphism. Nifedipine and Nimodipine are two such drugs. This study aimed to monitor the photodegradation of these two drugs and to establish the effect of particle size, polymorphism and β-Cyclodextrin (β-CD) on the rate of photodegradation. Different polymorphs (namely the amorphous and stable crystalline polymorphs) of the two drugs were prepared for use in the study. Mixtures of each drug with β-CD were also prepared for photostability studies. The mixtures were prepared in a 1:1 molar ratio. The rate of photodegradation was studied with a 500 W metal halide lamp in accordance to ICH guidelines. The study employed samples on a small scale where degradation was analysed with High Performance Liquid Chromatography, and also samples on a larger scale where degradation was monitored with Powder X-ray Diffraction. The two sets of results of observing the degradation process by two analytical techniques where compared in terms of their quantification methods. The extent of photodegradation was suitably modelled and fitted using the Avrami-Erofeyev kinetic equation. Smaller particle size showed increased photodegradation for Nimodipine; the effect was insignificant for Nifedipine however. For both drugs it was found that the amorphous polymorph underwent faster photodegradation. The study showed that β-CD caused an increase in photodegradation for both drugs under these experimental conditions.
- Full Text:
- Date Issued: 2011