The introduction of cyberhunts as a teaching and learning strategy to guide teachers towards the integration of computer technology in schools
- Authors: Du Plessis, André
- Date: 2010
- Subjects: Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9555 , http://hdl.handle.net/10948/1210 , Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Description: This study, which is based on a computer literacy teacher development programme that included introducing the teacher participants to the Internet, investigated whether the development of teacher ICT skills through the design of cyberhunts in a learning-as-design context, has the potential to promote the critical and developmental outcomes which form the basis of the South African National Curriculum Statement (NCS) and Draft White Paper on e-Education. The research was conducted within the post-positivist paradigm underpinned by a critical realist position and made use of qualitative and quantitative data1 gathering methods (mixed research) within an interpretative case study. Several different quantitative and qualitative data collection tools were used. Quantitative data gathering tools that had been used comprised of Likert scale questionnaires, a computer skills questionnaire, as well as certain sections within semi-closed-openended questionnaires. The qualitative data gathering tools that had been used were semi-closed-openended questionnaires, journal reflection sheets, observation and interviews. Ontologically the research was informed by a critical-realist perspective, epistemologically by a socio-cultural perspective; including situated learning within communities of practice; recognising the cognitive, social and situated learning dimension of teacher learning. Methodologically an interpretive case study approach was used, as the aim was to explore and investigate what the participants experienced, perceived and to understand the participants: what they felt, how they felt and why they felt and responded in certain ways. Initially the study focused on identifying how ready the participating schools and their participating teachers were in terms of the implementation and integration of Information and Communications Technology (ICT) with reference to first- and second order barriers. The findings suggest that addressing the first- and second order barriers is a vital aspect when assisting schools to move towards ICT integration. The next phase of the research focused on whether the cyberhunt design approach is capable of developing the critical outcomes of the NCS, whether it promotes motivation and interest, and whether it promotes collaboration. Both the quantitative and qualitative data portrayed positive results regarding the perceptions of the participating teachers in the cyberhunt design approach related to the critical and 1PLEASE NOTE: All the data referred to as in the appendix and all appendices are attached to this thesis on a CD containing the portable document format (PDF) files. This can be found at the back. iv developmental outcomes with reference to search and research, reading attitude, decision making, planning skills - which include time management and goal setting, knowledge and skills related to composing questions on different cognitive levels, computer skills, reflection and design skills. Positive results were also found related to audience, confidence, mental effort, motivation, interest and collaboration. The probabilities (p values) and practical statistical significance in the form of Cohen's d, were highly significant. The teachers’ final cyberhunt products suggest that the majority of the participants had obtained basic cyberhunt design skills. However, in spite of the positive results, it was found that not all teachers are yet ready to implement this approach exactly as it is intended. When interpreted within an activity theory perspective; the positive results might be attributed to the unmediated functioning of the rules, division of labour and community aspects of the theory, while the conditions required by complexity theory for the development of a complex learning community appear to have been met by the implementation of cyberhunts as a strategy. The conditions for enabling the development of a complex learning community; namely internal diversity, redundancy, decentralised control, organised randomness and neighbour interaction; also appear to have interacted with the unmediated aspects of activity theory in developing consensual rules and through the negotiation of the division of labour located within the community. In a like manner, positive results related to search and research, decision making, questioning, computer skills, reflection, design skills and audience reported can most likely be attributed to the functioning of the mediational tools as described by activity theory such as the computer technology, the Internet, the software that had been used and language. The data thus suggest that the interaction between both the unmediated elements and higher order mediated elements of activity theory, have most likely been the defining factors which created high levels of motivation, interest, collaboration and a positive classroom culture through which the critical and developmental outcomes of the South Africa curriculum can possibly be achieved within a complex learning community. The study also investigated how the teacher development process regarding ICT implementation should be managed. This study found that the acronym CRAR3FS2 holds the key to teacher development and classroom implementation. This acronym represents the verbs or actions that the participating teachers highly valued during implementation and what they have indicated as being important, namely: Care, Relate, Assess, Reflect, Read, Re-Plan, Feedback, Share and Support.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis, André
- Date: 2010
- Subjects: Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9555 , http://hdl.handle.net/10948/1210 , Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Description: This study, which is based on a computer literacy teacher development programme that included introducing the teacher participants to the Internet, investigated whether the development of teacher ICT skills through the design of cyberhunts in a learning-as-design context, has the potential to promote the critical and developmental outcomes which form the basis of the South African National Curriculum Statement (NCS) and Draft White Paper on e-Education. The research was conducted within the post-positivist paradigm underpinned by a critical realist position and made use of qualitative and quantitative data1 gathering methods (mixed research) within an interpretative case study. Several different quantitative and qualitative data collection tools were used. Quantitative data gathering tools that had been used comprised of Likert scale questionnaires, a computer skills questionnaire, as well as certain sections within semi-closed-openended questionnaires. The qualitative data gathering tools that had been used were semi-closed-openended questionnaires, journal reflection sheets, observation and interviews. Ontologically the research was informed by a critical-realist perspective, epistemologically by a socio-cultural perspective; including situated learning within communities of practice; recognising the cognitive, social and situated learning dimension of teacher learning. Methodologically an interpretive case study approach was used, as the aim was to explore and investigate what the participants experienced, perceived and to understand the participants: what they felt, how they felt and why they felt and responded in certain ways. Initially the study focused on identifying how ready the participating schools and their participating teachers were in terms of the implementation and integration of Information and Communications Technology (ICT) with reference to first- and second order barriers. The findings suggest that addressing the first- and second order barriers is a vital aspect when assisting schools to move towards ICT integration. The next phase of the research focused on whether the cyberhunt design approach is capable of developing the critical outcomes of the NCS, whether it promotes motivation and interest, and whether it promotes collaboration. Both the quantitative and qualitative data portrayed positive results regarding the perceptions of the participating teachers in the cyberhunt design approach related to the critical and 1PLEASE NOTE: All the data referred to as in the appendix and all appendices are attached to this thesis on a CD containing the portable document format (PDF) files. This can be found at the back. iv developmental outcomes with reference to search and research, reading attitude, decision making, planning skills - which include time management and goal setting, knowledge and skills related to composing questions on different cognitive levels, computer skills, reflection and design skills. Positive results were also found related to audience, confidence, mental effort, motivation, interest and collaboration. The probabilities (p values) and practical statistical significance in the form of Cohen's d, were highly significant. The teachers’ final cyberhunt products suggest that the majority of the participants had obtained basic cyberhunt design skills. However, in spite of the positive results, it was found that not all teachers are yet ready to implement this approach exactly as it is intended. When interpreted within an activity theory perspective; the positive results might be attributed to the unmediated functioning of the rules, division of labour and community aspects of the theory, while the conditions required by complexity theory for the development of a complex learning community appear to have been met by the implementation of cyberhunts as a strategy. The conditions for enabling the development of a complex learning community; namely internal diversity, redundancy, decentralised control, organised randomness and neighbour interaction; also appear to have interacted with the unmediated aspects of activity theory in developing consensual rules and through the negotiation of the division of labour located within the community. In a like manner, positive results related to search and research, decision making, questioning, computer skills, reflection, design skills and audience reported can most likely be attributed to the functioning of the mediational tools as described by activity theory such as the computer technology, the Internet, the software that had been used and language. The data thus suggest that the interaction between both the unmediated elements and higher order mediated elements of activity theory, have most likely been the defining factors which created high levels of motivation, interest, collaboration and a positive classroom culture through which the critical and developmental outcomes of the South Africa curriculum can possibly be achieved within a complex learning community. The study also investigated how the teacher development process regarding ICT implementation should be managed. This study found that the acronym CRAR3FS2 holds the key to teacher development and classroom implementation. This acronym represents the verbs or actions that the participating teachers highly valued during implementation and what they have indicated as being important, namely: Care, Relate, Assess, Reflect, Read, Re-Plan, Feedback, Share and Support.
- Full Text:
- Date Issued: 2010
The Intsomi Ambassadors: using communicative ecologies to enhance home literacy practices amongst working class parents in Grahamstown
- Authors: Gush, Cathy
- Date: 2019
- Subjects: Communication in economic development -- South Africa -- Makhanda , Literacy -- South Africa -- Makhanda , Literacy programs -- South Africa -- Makhanda , Education -- Parent participation -- South Africa -- Makhanda , Intsomi Project
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/71459 , vital:29855
- Description: Utilising theories of Communication for Development, the research explores how literacy practices in the homes of a group of working class, English second language parents in Grahamstown are affected by the introduction of new literacy material and insights Furthermore, it discusses how, and through which forms of media, these observed dynamics and changes in practice are best communicated to similar households. The issue of children's literacy development in South Africa is of serious concern, in particular the role that parents play and the level of support they give through home literacy practices. The context is one in which South African children have performed very poorly with regard to literacy levels in international benchmark testing as well as in national assessments. The summary report on the Progress in International Reading Literacy Study (PIRLS) found that some of the factors contributing to these poor results were the lack of reading resources in homes, as well as the lack of strong home-school partnerships in which parents took up the role of co-educators, or even of primary educators at the preschool stage. A group of parents employed by Rhodes University at the Grade 1 - 5 levels signed up to be the recipients of a programme supporting the literacy development of their primary and pre-primary school children. The Intsomi Project is run by the Rhodes Community Engagement Office as part of the Vice-Chancellor’s Education Initiative and provides close to 100 families with weekly reading material and educational games for their children, as well as workshops on the use of these materials and how they might benefit the children. Following a Participatory Action Research approach, a “vanguard” group of parent participants, known as the Intsomi Ambassadors, developed their role as literacy activists, becoming co-creators of media messages that utilised and built on the first stage of their communication within the group. The research explored how the principles and techniques of development support communication, and those of communicative ecologies, could be applied to explore, enhance and disseminate those qualitative changes in behaviour within households that positively affect children’s literacy development. In the process, it aimed to explore whether media representations that reflect the stories of parents trying out new literacy practices can create authentic, endogenous messages that resonate with people in similar circumstances, and can stimulate debate around the issue.
- Full Text:
- Date Issued: 2019
- Authors: Gush, Cathy
- Date: 2019
- Subjects: Communication in economic development -- South Africa -- Makhanda , Literacy -- South Africa -- Makhanda , Literacy programs -- South Africa -- Makhanda , Education -- Parent participation -- South Africa -- Makhanda , Intsomi Project
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/71459 , vital:29855
- Description: Utilising theories of Communication for Development, the research explores how literacy practices in the homes of a group of working class, English second language parents in Grahamstown are affected by the introduction of new literacy material and insights Furthermore, it discusses how, and through which forms of media, these observed dynamics and changes in practice are best communicated to similar households. The issue of children's literacy development in South Africa is of serious concern, in particular the role that parents play and the level of support they give through home literacy practices. The context is one in which South African children have performed very poorly with regard to literacy levels in international benchmark testing as well as in national assessments. The summary report on the Progress in International Reading Literacy Study (PIRLS) found that some of the factors contributing to these poor results were the lack of reading resources in homes, as well as the lack of strong home-school partnerships in which parents took up the role of co-educators, or even of primary educators at the preschool stage. A group of parents employed by Rhodes University at the Grade 1 - 5 levels signed up to be the recipients of a programme supporting the literacy development of their primary and pre-primary school children. The Intsomi Project is run by the Rhodes Community Engagement Office as part of the Vice-Chancellor’s Education Initiative and provides close to 100 families with weekly reading material and educational games for their children, as well as workshops on the use of these materials and how they might benefit the children. Following a Participatory Action Research approach, a “vanguard” group of parent participants, known as the Intsomi Ambassadors, developed their role as literacy activists, becoming co-creators of media messages that utilised and built on the first stage of their communication within the group. The research explored how the principles and techniques of development support communication, and those of communicative ecologies, could be applied to explore, enhance and disseminate those qualitative changes in behaviour within households that positively affect children’s literacy development. In the process, it aimed to explore whether media representations that reflect the stories of parents trying out new literacy practices can create authentic, endogenous messages that resonate with people in similar circumstances, and can stimulate debate around the issue.
- Full Text:
- Date Issued: 2019
The Invaders
- Date: 19??
- Subjects: UNCATALOGUED
- Type: Image
- Identifier: http://hdl.handle.net/10962/221977 , vital:48809 , DTC-013
- Description: The Invaders pose by the beach before their overseas tour. , Use of this resource is governed by the terms and conditions of the Creative Commons "Attribution-NonCommercial-ShareAlike" License (http://creativecommons.org/licenses/by-nc-sa/2.0/) (NEVER CAHNGE THIS FIELD)
- Full Text: false
- Date Issued: 19??
- Date: 19??
- Subjects: UNCATALOGUED
- Type: Image
- Identifier: http://hdl.handle.net/10962/221977 , vital:48809 , DTC-013
- Description: The Invaders pose by the beach before their overseas tour. , Use of this resource is governed by the terms and conditions of the Creative Commons "Attribution-NonCommercial-ShareAlike" License (http://creativecommons.org/licenses/by-nc-sa/2.0/) (NEVER CAHNGE THIS FIELD)
- Full Text: false
- Date Issued: 19??
The invasion autecology of Iris pseudacorus L. (Iridaceae) in South Africa
- Authors: Sandenbergh, Emma
- Date: 2022-04-06
- Subjects: Iris pseudacorus South Africa , Invasive plants South Africa , Aquatic weeds South Africa , Plant genetics South Africa , Freshwater ecology South Africa , Iris pseudacorus Geographical distribution , Phytogeography
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232272 , vital:49977
- Description: Iris pseudacorus L. (Iridaceae) is an emergent aquatic macrophyte originating from Europe, north Africa, and western Asia, and is becoming an increasingly problematic invader in South Africa. By forming dense rhizomatic mats in the absence of natural enemies, I. pseudacorus outcompetes co-occurring indigenous biota, causing serious environmental and socioeconomic challenges. Iris pseudacorus is a declared invader in South Africa, Argentina, New Zealand, the United States of America, and Canada, but little information is known regarding the species’ invasive potential, particularly in the southern hemisphere, hindering the effectiveness of control efforts. This study addresses this knowledge gap in a South African context, providing valuable insight into the invasion autecology of I. pseudacorus in South Africa. For effective management and control of I. pseudacorus in South Africa and the global south, its distribution and invasive potential must be determined, and its population genetics understood. Hence, this study aimed to map the current confirmed distribution of I. pseudacorus populations in South Africa, investigating the relative abundance of I. pseudacorus individuals in each population, and comparing their sexual reproductive outputs. Moreover, this study assessed the competitive interactions between I. pseudacorus and co-occurring native species T. capensis, and examined the genetic diversity present between and within South African I. pseudacorus populations. Through field surveys, I. pseudacorus infestations were confirmed in eight of the country’s nine provinces, with the highest number of infestations recorded in the urban hubs, and greatest population abundances reported in the warmer, wetter regions of South Africa. These surveys indicated that South African I. pseudacorus populations have enhanced their sexual reproductive output relative to native range populations, and a germination rate of ~ 83 % was determined in the laboratory. The results of a common garden competition experiment indicated that T. capensis may be a superior competitor over I. pseudacorus, but this was not supported by field observations, and may be a result of the short duration of the experiment. Using inter-simple sequence repeats (ISSRs), high genetic diversity was observed within and between populations of I. pseudacorus, indicating the employment of sexual reproductive strategies, and providing evidence for gene-flow between and within populations. Moreover, a weak negative correlation was observed between geographic distance and genetic similarity, ii indicating a largely anthropogenic spread of I. pseudacorus, and suggesting the occurrence of fewer founding events than reported in the United States. This study provides useful insight into the invasion autecology of I. pseudacorus in South Africa, contributing to the ongoing research surrounding I. pseudacorus invasions worldwide, particularly in the southern hemisphere. These results contribute to the development of appropriate adaptive and integrated management strategies to control I. pseudacorus invasions in South Africa, and should be implemented before South African I. pseudacorus infestations reach the severity observed elsewhere. , Thesis (MSc) -- Faculty of Science, Botany, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Sandenbergh, Emma
- Date: 2022-04-06
- Subjects: Iris pseudacorus South Africa , Invasive plants South Africa , Aquatic weeds South Africa , Plant genetics South Africa , Freshwater ecology South Africa , Iris pseudacorus Geographical distribution , Phytogeography
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232272 , vital:49977
- Description: Iris pseudacorus L. (Iridaceae) is an emergent aquatic macrophyte originating from Europe, north Africa, and western Asia, and is becoming an increasingly problematic invader in South Africa. By forming dense rhizomatic mats in the absence of natural enemies, I. pseudacorus outcompetes co-occurring indigenous biota, causing serious environmental and socioeconomic challenges. Iris pseudacorus is a declared invader in South Africa, Argentina, New Zealand, the United States of America, and Canada, but little information is known regarding the species’ invasive potential, particularly in the southern hemisphere, hindering the effectiveness of control efforts. This study addresses this knowledge gap in a South African context, providing valuable insight into the invasion autecology of I. pseudacorus in South Africa. For effective management and control of I. pseudacorus in South Africa and the global south, its distribution and invasive potential must be determined, and its population genetics understood. Hence, this study aimed to map the current confirmed distribution of I. pseudacorus populations in South Africa, investigating the relative abundance of I. pseudacorus individuals in each population, and comparing their sexual reproductive outputs. Moreover, this study assessed the competitive interactions between I. pseudacorus and co-occurring native species T. capensis, and examined the genetic diversity present between and within South African I. pseudacorus populations. Through field surveys, I. pseudacorus infestations were confirmed in eight of the country’s nine provinces, with the highest number of infestations recorded in the urban hubs, and greatest population abundances reported in the warmer, wetter regions of South Africa. These surveys indicated that South African I. pseudacorus populations have enhanced their sexual reproductive output relative to native range populations, and a germination rate of ~ 83 % was determined in the laboratory. The results of a common garden competition experiment indicated that T. capensis may be a superior competitor over I. pseudacorus, but this was not supported by field observations, and may be a result of the short duration of the experiment. Using inter-simple sequence repeats (ISSRs), high genetic diversity was observed within and between populations of I. pseudacorus, indicating the employment of sexual reproductive strategies, and providing evidence for gene-flow between and within populations. Moreover, a weak negative correlation was observed between geographic distance and genetic similarity, ii indicating a largely anthropogenic spread of I. pseudacorus, and suggesting the occurrence of fewer founding events than reported in the United States. This study provides useful insight into the invasion autecology of I. pseudacorus in South Africa, contributing to the ongoing research surrounding I. pseudacorus invasions worldwide, particularly in the southern hemisphere. These results contribute to the development of appropriate adaptive and integrated management strategies to control I. pseudacorus invasions in South Africa, and should be implemented before South African I. pseudacorus infestations reach the severity observed elsewhere. , Thesis (MSc) -- Faculty of Science, Botany, 2022
- Full Text:
- Date Issued: 2022-04-06
The invasion ecology of Nymphaea mexicana Zucc. (Mexican Water lily) in South Africa
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
The invasion ecology of Pontederia cordata L. (Pontederiaceae) in South Africa
- Authors: Wansell, Sage Nora-Lee
- Date: 2021
- Subjects: Plant invsions -- South AFrica , Invasive plants -- Ecology -- South Africa , Pontederiaceae -- South AFrica
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172433 , vital:42200
- Description: Pontederia cordata L. (Pontederiaceae) is a tristylous invasive macrophyte – originating from North and South America – that has caused detrimental environmental, agricultural and socio-economic impacts in South Africa (SA). This novel study investigates the invasive ecology of P. cordata in SA by determining population genetics, pollination ecology and floral traits. Preliminary field surveys suggest that only one of three tristylous forms of P. cordata is invading SA and no seeds have been observed in any invasive populations. This study therefore determined the population genetics, mode of spread of P. cordata in SA and possible reasons for the lack of seed production, as well as providing suggestions for future control and management strategies. Inter Simple Sequence Repeats of leaf samples from invasive populations in SA and the native range of the United States of America (USA) were performed to determine the population genetics of P. cordata. The clarification of population structure of an alien invasive plant can provide insight into founder effects, introduction events and modes of spread and is important for the development of management plans such as biological control. Results from the genetic analyses indicated that P. cordata populations have low genetic diversity within and amongst invasive populations in comparison to native populations. This suggests that high gene flow and sexual reproduction is not present in invasive populations, and that only a single or very few introductory events have occurred in SA. Furthermore, invasive P. cordata populations shared the highest genetic similarity with native samples from Belle Haven, Virginia, USA, and thus further sampling and future genetic surveys should be conducted in this area to identify source populations to survey for potential biological control agents. Following these findings, I investigated whether sexual reproduction and seed production is absent from invasive P. cordata populations in SA as speculated. Floral traits from populations throughout all the invaded provinces were measured and, along with pollen grain measurements, it was determined that only short-morphed plants are present in SA. It was speculated that the absence of native pollinators in the invasive range may be responsible for the absence of sexual reproduction. However, a pollination study confirmed the presence of generalist insect pollinators. Thereafter, artificial pollination experiments on 8 865 flowers were conducted to determine whether an incompatibility system was present which prevented seed production. No seeds were produced and it was concluded that illegitimate pollination of the short-morphed plants prevented seed production and rhizomes are responsible for the invasion of P. cordata throughout SA. The implications of these findings and possible management strategies such as biological control is discussed in Chapter 4. These findings suggest that control programmes should target the plants rhizomes to prevent and reduce spread. Preventing the introduction of medium- and long-morphed plants into SA is crucial to prevent P. cordata from producing seeds and intensifying invasion further through both asexual and sexual spread.
- Full Text:
- Date Issued: 2021
- Authors: Wansell, Sage Nora-Lee
- Date: 2021
- Subjects: Plant invsions -- South AFrica , Invasive plants -- Ecology -- South Africa , Pontederiaceae -- South AFrica
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172433 , vital:42200
- Description: Pontederia cordata L. (Pontederiaceae) is a tristylous invasive macrophyte – originating from North and South America – that has caused detrimental environmental, agricultural and socio-economic impacts in South Africa (SA). This novel study investigates the invasive ecology of P. cordata in SA by determining population genetics, pollination ecology and floral traits. Preliminary field surveys suggest that only one of three tristylous forms of P. cordata is invading SA and no seeds have been observed in any invasive populations. This study therefore determined the population genetics, mode of spread of P. cordata in SA and possible reasons for the lack of seed production, as well as providing suggestions for future control and management strategies. Inter Simple Sequence Repeats of leaf samples from invasive populations in SA and the native range of the United States of America (USA) were performed to determine the population genetics of P. cordata. The clarification of population structure of an alien invasive plant can provide insight into founder effects, introduction events and modes of spread and is important for the development of management plans such as biological control. Results from the genetic analyses indicated that P. cordata populations have low genetic diversity within and amongst invasive populations in comparison to native populations. This suggests that high gene flow and sexual reproduction is not present in invasive populations, and that only a single or very few introductory events have occurred in SA. Furthermore, invasive P. cordata populations shared the highest genetic similarity with native samples from Belle Haven, Virginia, USA, and thus further sampling and future genetic surveys should be conducted in this area to identify source populations to survey for potential biological control agents. Following these findings, I investigated whether sexual reproduction and seed production is absent from invasive P. cordata populations in SA as speculated. Floral traits from populations throughout all the invaded provinces were measured and, along with pollen grain measurements, it was determined that only short-morphed plants are present in SA. It was speculated that the absence of native pollinators in the invasive range may be responsible for the absence of sexual reproduction. However, a pollination study confirmed the presence of generalist insect pollinators. Thereafter, artificial pollination experiments on 8 865 flowers were conducted to determine whether an incompatibility system was present which prevented seed production. No seeds were produced and it was concluded that illegitimate pollination of the short-morphed plants prevented seed production and rhizomes are responsible for the invasion of P. cordata throughout SA. The implications of these findings and possible management strategies such as biological control is discussed in Chapter 4. These findings suggest that control programmes should target the plants rhizomes to prevent and reduce spread. Preventing the introduction of medium- and long-morphed plants into SA is crucial to prevent P. cordata from producing seeds and intensifying invasion further through both asexual and sexual spread.
- Full Text:
- Date Issued: 2021
The invasion of pteronia incana (blue bush) along a range of gradients in the Eastern Cape Province : it's spectral chacteristics and implications for soil moisture
- Authors: Odindi, John Odhiambo
- Date: 2009
- Subjects: Invasive plants -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10650 , http://hdl.handle.net/10948/1052 , Invasive plants -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape
- Description: Extensive areas of the Eastern Cape Province have been invaded by Pteronia incana (Blue bush), a non-palatable patchy invader shrub that is associated with soil degradation. This study sought to establish the relationship between the invasion and a range of eco-physical and land use gradients. The impact of the invader on soil moisture flux was investigated by comparing soil moisture variations under grass, bare and P. incana invaded surfaces. Field based and laboratory spectroscopy was used to validate P. incana spectral characteristics identified from multi-temporal High Resolution Imagery (HRI). A belt transect was surveyed to gain an understanding of the occurrence of the invasion across land use, isohyetic, geologic, vegetation, pedologic and altitudinal gradients. Soil moisture sensors were calibrated and installed under the respective surfaces in order to determine soil moisture trends over a period of six months. To classify the surfaces using HRI, the pixel and sub-pixel based Perpendicular Vegetation Index (PVI) and Spectral Mixture Analysis (SMA) respectively were used. There was no clear trend established between the underlying geology and P. incana invasion. Land disturbance in general was strongly associated with the invasion, as the endemic zone for the invasion mainly comprised abandoned cultivated and overgrazed land. Isohyetic gradients emerged as the major limiting factor of the invasion; a distinct zone below 619mm of mean annual rainfall was identified as the apparent boundary for the invasion. Low organic matter content identified under invaded areas was attributed to the patchy nature of the invader, leading to loss of the top soil in the bare inter-patch areas. The area covered by grass had consistently higher moisture values than P. incana and bare surfaces. The difference in post-rainfall moisture retention between grass and P. incana surfaces was significant up to about six days, after which a near parallel trend was noticed towards the ensuing rainfall episode. Whereas a higher amount of moisture was recorded on grass, the surface experienced moisture loss faster than the invaded and bare surfaces after each rainfall episode. ii There was consistency in multi-temporal Digital Number (DN) values for the surfaces investigated. The typically low P. incana reflectance in the Near Infrared band, identified from the multi-temporal HRI was validated by field and laboratory spectroscopy. The PVI showed clear spectral separability between all the land surfaces in the respective multi-temporal HRI. The consistence of the PVI with the unmixed surface image fractions from the SMA illustrates that using HRI, the effectiveness of the PVI is not impeded by the mixed pixel problem. Results of the laboratory spectroscopy that validated HRI analyses showed that P. incana’s typically low reflectance is a function of its leaf canopy, as higher proportions of leaves gave a higher reflectance. Future research directions could focus on comparisons between P. incana and typical green vegetation internal leaf structures as potential causes of spectral differences. Collection of spectra for P incana and other invader vegetation types, some of which have similar characteristics, with a view to assembling a spectral library for delineating invaded environments using imagery, is another research direction.
- Full Text:
- Date Issued: 2009
- Authors: Odindi, John Odhiambo
- Date: 2009
- Subjects: Invasive plants -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10650 , http://hdl.handle.net/10948/1052 , Invasive plants -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape
- Description: Extensive areas of the Eastern Cape Province have been invaded by Pteronia incana (Blue bush), a non-palatable patchy invader shrub that is associated with soil degradation. This study sought to establish the relationship between the invasion and a range of eco-physical and land use gradients. The impact of the invader on soil moisture flux was investigated by comparing soil moisture variations under grass, bare and P. incana invaded surfaces. Field based and laboratory spectroscopy was used to validate P. incana spectral characteristics identified from multi-temporal High Resolution Imagery (HRI). A belt transect was surveyed to gain an understanding of the occurrence of the invasion across land use, isohyetic, geologic, vegetation, pedologic and altitudinal gradients. Soil moisture sensors were calibrated and installed under the respective surfaces in order to determine soil moisture trends over a period of six months. To classify the surfaces using HRI, the pixel and sub-pixel based Perpendicular Vegetation Index (PVI) and Spectral Mixture Analysis (SMA) respectively were used. There was no clear trend established between the underlying geology and P. incana invasion. Land disturbance in general was strongly associated with the invasion, as the endemic zone for the invasion mainly comprised abandoned cultivated and overgrazed land. Isohyetic gradients emerged as the major limiting factor of the invasion; a distinct zone below 619mm of mean annual rainfall was identified as the apparent boundary for the invasion. Low organic matter content identified under invaded areas was attributed to the patchy nature of the invader, leading to loss of the top soil in the bare inter-patch areas. The area covered by grass had consistently higher moisture values than P. incana and bare surfaces. The difference in post-rainfall moisture retention between grass and P. incana surfaces was significant up to about six days, after which a near parallel trend was noticed towards the ensuing rainfall episode. Whereas a higher amount of moisture was recorded on grass, the surface experienced moisture loss faster than the invaded and bare surfaces after each rainfall episode. ii There was consistency in multi-temporal Digital Number (DN) values for the surfaces investigated. The typically low P. incana reflectance in the Near Infrared band, identified from the multi-temporal HRI was validated by field and laboratory spectroscopy. The PVI showed clear spectral separability between all the land surfaces in the respective multi-temporal HRI. The consistence of the PVI with the unmixed surface image fractions from the SMA illustrates that using HRI, the effectiveness of the PVI is not impeded by the mixed pixel problem. Results of the laboratory spectroscopy that validated HRI analyses showed that P. incana’s typically low reflectance is a function of its leaf canopy, as higher proportions of leaves gave a higher reflectance. Future research directions could focus on comparisons between P. incana and typical green vegetation internal leaf structures as potential causes of spectral differences. Collection of spectra for P incana and other invader vegetation types, some of which have similar characteristics, with a view to assembling a spectral library for delineating invaded environments using imagery, is another research direction.
- Full Text:
- Date Issued: 2009
The invasive grass genus Nassella in South Africa: A synthesis
- Mapaura Anthony, Canavan, Kim N, Richardson, David M, Clark, Vincent R, Steenhuisen, Sandy-Lynn
- Authors: Mapaura Anthony , Canavan, Kim N , Richardson, David M , Clark, Vincent R , Steenhuisen, Sandy-Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424842 , vital:72188 , xlink:href="https://doi.org/10.1016/j.sajb.2020.08.031"
- Description: Three species of Nassella have naturalized in South Africa. Nassella trichotoma and N. tenuissima are declared weeds under category 1b of the National Environmental Management: Biodiversity Act (NEM:BA) and occur mainly in the montane grasslands of the Western and Eastern Cape provinces. Nassella neesiana is not listed in NEM:BA but is naturalized in the Eastern Cape, Western Cape and Free State provinces. Research conducted in the 1970s and 1980s led to vigorous government-funded awareness and control campaigns which ended in 2000. No research on Nassella distribution or control has been undertaken since then. Despite this hiatus, Nassella remains a dangerous genus in southern Africa, given the serious impacts of these species in similar social-ecological systems in Australia and New Zealand. This paper presents a synthesis of available information about Nassella invasions in South Africa and identifies research gaps. It specifically addresses these questions: What identification issues exist? What is the current spatial distribution of Nassella? What is the autecology of the genus? What are the social-ecological impacts of Nassella? What control measures are currently applied and what are their strengths and limitations? What do we know about Nassella distribution and its response to climate change? This paper highlights many knowledge gaps about Nassella, such as the species’ current distribution range, field identification and detection difficulties, and the uncoordinated control efforts that require urgent research to inform an effective management response.
- Full Text:
- Date Issued: 2020
- Authors: Mapaura Anthony , Canavan, Kim N , Richardson, David M , Clark, Vincent R , Steenhuisen, Sandy-Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424842 , vital:72188 , xlink:href="https://doi.org/10.1016/j.sajb.2020.08.031"
- Description: Three species of Nassella have naturalized in South Africa. Nassella trichotoma and N. tenuissima are declared weeds under category 1b of the National Environmental Management: Biodiversity Act (NEM:BA) and occur mainly in the montane grasslands of the Western and Eastern Cape provinces. Nassella neesiana is not listed in NEM:BA but is naturalized in the Eastern Cape, Western Cape and Free State provinces. Research conducted in the 1970s and 1980s led to vigorous government-funded awareness and control campaigns which ended in 2000. No research on Nassella distribution or control has been undertaken since then. Despite this hiatus, Nassella remains a dangerous genus in southern Africa, given the serious impacts of these species in similar social-ecological systems in Australia and New Zealand. This paper presents a synthesis of available information about Nassella invasions in South Africa and identifies research gaps. It specifically addresses these questions: What identification issues exist? What is the current spatial distribution of Nassella? What is the autecology of the genus? What are the social-ecological impacts of Nassella? What control measures are currently applied and what are their strengths and limitations? What do we know about Nassella distribution and its response to climate change? This paper highlights many knowledge gaps about Nassella, such as the species’ current distribution range, field identification and detection difficulties, and the uncoordinated control efforts that require urgent research to inform an effective management response.
- Full Text:
- Date Issued: 2020
The invasive ‘mothcatcher’ (Araujia sericifera Brot.; Asclepiadoideae) co-opts native honeybees as its primary pollinator in South Africa
- Coombs, Gareth, Peter, Craig I
- Authors: Coombs, Gareth , Peter, Craig I
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6510 , http://hdl.handle.net/10962/d1005937
- Description: Background and aims: Successful invasive plants such as Araujia sericifera usually either are capable of automatic self-pollination or maintain pollinator services by having generalized pollination systems to make use of local pollinators in the invaded range. Alternatively, plants must co-opt new pollinators with similar morphology to native pollinators or reproduce asexually. We aimed to document the pollination biology of A. sericifera in South Africa. Given the success of this species as an invader, we predicted that sexual reproduction occurs either through self-pollination or because A. sericifera has successfully co-opted native insect pollinators. Methodology: We examined the pollination biology of the South American A. sericifera in South Africa. We documented the effective pollinators including a comparison of the efficacy of nocturnal versus diurnal pollinators as well as the breeding system and long-term natural levels of the pollination success of this species. Principal results: We found that native honeybees (Apis mellifera) were the main pollinators of A. sericifera in South Africa. Visiting moths are unimportant pollinators despite being attracted by the pale colour and nocturnal scent of the flowers. Plants from the Grahamstown population were incapable of autonomous self-pollination but pollinator-mediated self-pollination does occur. However, the highest fruit initiation resulted from out-crossed pollination treatments. The high pollen transfer efficiency of this species was comparable to other hymenopteranpollinated exotic and native milkweeds, suggesting that A. sericifera maintains pollinator services at levels experienced by indigenous asclepiad species. Conclusions: Araujia sericifera reproduces successfully in South Africa due to a combined ability of this species to attract and exploit native honeybees as its pollinators and of individual plants to set fruit from pollinator-mediated self-pollination.
- Full Text:
- Date Issued: 2010
- Authors: Coombs, Gareth , Peter, Craig I
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6510 , http://hdl.handle.net/10962/d1005937
- Description: Background and aims: Successful invasive plants such as Araujia sericifera usually either are capable of automatic self-pollination or maintain pollinator services by having generalized pollination systems to make use of local pollinators in the invaded range. Alternatively, plants must co-opt new pollinators with similar morphology to native pollinators or reproduce asexually. We aimed to document the pollination biology of A. sericifera in South Africa. Given the success of this species as an invader, we predicted that sexual reproduction occurs either through self-pollination or because A. sericifera has successfully co-opted native insect pollinators. Methodology: We examined the pollination biology of the South American A. sericifera in South Africa. We documented the effective pollinators including a comparison of the efficacy of nocturnal versus diurnal pollinators as well as the breeding system and long-term natural levels of the pollination success of this species. Principal results: We found that native honeybees (Apis mellifera) were the main pollinators of A. sericifera in South Africa. Visiting moths are unimportant pollinators despite being attracted by the pale colour and nocturnal scent of the flowers. Plants from the Grahamstown population were incapable of autonomous self-pollination but pollinator-mediated self-pollination does occur. However, the highest fruit initiation resulted from out-crossed pollination treatments. The high pollen transfer efficiency of this species was comparable to other hymenopteranpollinated exotic and native milkweeds, suggesting that A. sericifera maintains pollinator services at levels experienced by indigenous asclepiad species. Conclusions: Araujia sericifera reproduces successfully in South Africa due to a combined ability of this species to attract and exploit native honeybees as its pollinators and of individual plants to set fruit from pollinator-mediated self-pollination.
- Full Text:
- Date Issued: 2010
The invertebrates of temporary rivers in the Eastern Cape, South Africa
- Authors: Uys, Amanda Cloete
- Date: 1998
- Subjects: Rivers -- South Africa -- Eastern Cape Stream ecology -- South Africa -- Eastern Cape Freshwater invertebrates -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5628 , http://hdl.handle.net/10962/d1004908
- Description: Temporary rivers in dryland regions are subject to highly variable and unpredictable rainfall and flow, and are considered unstable systems relative to perennial rivers of temperate zones. Little is known of the ecology of South Africa's temporary rivers, despite their abundance. The research presented focusses on the aquatic invertebrates inhabiting intermittently-flowing rivers in the 'arid corridor' of the Eastern Cape, South Africa. The major aims of the work were: to investigate which invertebrates inhabit these rivers, how the fauna is affected by environmental variability at various spatial and temporal scales, whether or not a characteristic fauna can be associated with these rivers or the hydrological phases which characterise them, and to establish to what extent faunal overlap occurs between different temporary rivers and between natural and modified temporary and perennial rivers. Research results indicate that the fauna of the Eastern Cape temporary rivers shows little structure at the scales of investigation, and that communities are generally non-equilibrial in character. The major forces shaping the biota are considered to be physical rather than biological, and the most important of these are: present and antecedent hydrological conditions and their duration; time of year; and biotope character, extent and heterogeneity. Three groups of fauna were identified as inhabitants of the temporary rivers: 'residents', 'facultative taxa' and 'opportunist colonists'. Taxa were tentatively allocated to these groups. Faunal resemblance was fairly high in Eastern Cape temporary rivers at the level of family, but not at more detailed taxonomic levels. A comparison between faunas of temporary and perennial rivers in different regions of South Africa illustrated the influence of geographical location on diversity. Within regions, however, there was no indication that perennial rivers were more diverse than intermittent rivers. The relatively high diversities in temporary rivers in this study are attributed at least in part to the heterogeneity in surface water conditions over time. A conceptual framework envisioning a continuum between perennial and temporary rivers is proposed as a basis for ongoing research into these rivers. A supporting terminology for the range of river flow types in South Africa is presented.
- Full Text:
- Date Issued: 1998
- Authors: Uys, Amanda Cloete
- Date: 1998
- Subjects: Rivers -- South Africa -- Eastern Cape Stream ecology -- South Africa -- Eastern Cape Freshwater invertebrates -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5628 , http://hdl.handle.net/10962/d1004908
- Description: Temporary rivers in dryland regions are subject to highly variable and unpredictable rainfall and flow, and are considered unstable systems relative to perennial rivers of temperate zones. Little is known of the ecology of South Africa's temporary rivers, despite their abundance. The research presented focusses on the aquatic invertebrates inhabiting intermittently-flowing rivers in the 'arid corridor' of the Eastern Cape, South Africa. The major aims of the work were: to investigate which invertebrates inhabit these rivers, how the fauna is affected by environmental variability at various spatial and temporal scales, whether or not a characteristic fauna can be associated with these rivers or the hydrological phases which characterise them, and to establish to what extent faunal overlap occurs between different temporary rivers and between natural and modified temporary and perennial rivers. Research results indicate that the fauna of the Eastern Cape temporary rivers shows little structure at the scales of investigation, and that communities are generally non-equilibrial in character. The major forces shaping the biota are considered to be physical rather than biological, and the most important of these are: present and antecedent hydrological conditions and their duration; time of year; and biotope character, extent and heterogeneity. Three groups of fauna were identified as inhabitants of the temporary rivers: 'residents', 'facultative taxa' and 'opportunist colonists'. Taxa were tentatively allocated to these groups. Faunal resemblance was fairly high in Eastern Cape temporary rivers at the level of family, but not at more detailed taxonomic levels. A comparison between faunas of temporary and perennial rivers in different regions of South Africa illustrated the influence of geographical location on diversity. Within regions, however, there was no indication that perennial rivers were more diverse than intermittent rivers. The relatively high diversities in temporary rivers in this study are attributed at least in part to the heterogeneity in surface water conditions over time. A conceptual framework envisioning a continuum between perennial and temporary rivers is proposed as a basis for ongoing research into these rivers. A supporting terminology for the range of river flow types in South Africa is presented.
- Full Text:
- Date Issued: 1998
The investigation of alternative processes for the oxidation of phenol
- Authors: Pongoma, Basanda
- Date: 2010
- Subjects: Phenol , Hydroquinone
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10381 , http://hdl.handle.net/10948/1479 , Phenol , Hydroquinone
- Description: The electrochemical oxidation of phenol can be considered as an important process for either producing value added products such as hydroquinone and catechol or for the removal of the phenol from waste water streams to form carbon dioxide. This process had been extensively studied with the main focus on type of anode material used. Even though the anode material could be made from a range of materials, this study focused on using PbO2 as anode material that was made by using Pb-acid battery principles in designing a microporous electrode. In this study, the focus was on using lead dioxide as an anode material that was made by using the formation principles used in the manufacturing of Pb-acid batteries. This allowed for the construction of an electrochemical flow-through micro-porous reactor that contained PbO2 as the anode and Pb as the cathode, allowing for a solution containing phenol to flow through the cell continuously. By applying a suitable potential across the cell, the almost complete oxidation of phenol would occur to form benzoquinone, which was followed by the sequential reduction to other products such as hydroquinone and catechol. The system was shown to be made up of tightly packed micro-porous material that had a very high surface area-to-volume ratio. The study showed that between 80 to 90 percent successful conversion of a 50 mM solution of phenol could be achieved by optimizing the continuous flow process of up to 500 minutes. The main reaction product from this process was hydroquinone, of up to 60 percent with a number of the minor products of which not all could be identified. In order to utilize the characteristics of this reactor system, its design and reaction conditions such as applied potential, phenol concentration, co-solvent concentration and support electrolyte concentration were investigated to optimize the convection of phenol and the yield of hydroquinone.
- Full Text:
- Date Issued: 2010
- Authors: Pongoma, Basanda
- Date: 2010
- Subjects: Phenol , Hydroquinone
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10381 , http://hdl.handle.net/10948/1479 , Phenol , Hydroquinone
- Description: The electrochemical oxidation of phenol can be considered as an important process for either producing value added products such as hydroquinone and catechol or for the removal of the phenol from waste water streams to form carbon dioxide. This process had been extensively studied with the main focus on type of anode material used. Even though the anode material could be made from a range of materials, this study focused on using PbO2 as anode material that was made by using Pb-acid battery principles in designing a microporous electrode. In this study, the focus was on using lead dioxide as an anode material that was made by using the formation principles used in the manufacturing of Pb-acid batteries. This allowed for the construction of an electrochemical flow-through micro-porous reactor that contained PbO2 as the anode and Pb as the cathode, allowing for a solution containing phenol to flow through the cell continuously. By applying a suitable potential across the cell, the almost complete oxidation of phenol would occur to form benzoquinone, which was followed by the sequential reduction to other products such as hydroquinone and catechol. The system was shown to be made up of tightly packed micro-porous material that had a very high surface area-to-volume ratio. The study showed that between 80 to 90 percent successful conversion of a 50 mM solution of phenol could be achieved by optimizing the continuous flow process of up to 500 minutes. The main reaction product from this process was hydroquinone, of up to 60 percent with a number of the minor products of which not all could be identified. In order to utilize the characteristics of this reactor system, its design and reaction conditions such as applied potential, phenol concentration, co-solvent concentration and support electrolyte concentration were investigated to optimize the convection of phenol and the yield of hydroquinone.
- Full Text:
- Date Issued: 2010
The investigation of chemical variation in the stems and rhizomes of cissampelos capensis l. f. (menispermaceae) the Eastern Cape medicinal plant
- Authors: Latolla, Nehemiah Solomon
- Date: 2017
- Subjects: Plants -- Composition Medicinal plants Endemic plants
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13970 , vital:27362
- Description: Cissampelos capensis L. f. (Menispermaceae) commonly known as “Mayisake” (Xhosa) and “Dawidjieswortel” (Afrikaans) is the most commonly used medicinal plant of the Menispermaceae family in South Africa. The rhizomes of Cissampelos capensis are the most used part of the plant to treat illnesses. This poses a threat to the ongoing conservation of this valuable endemic species. Thus, we studied the chemical variation and subsequently the bioactivity in the stems and rhizomes of Cissampelos capensis, the Eastern Cape medicinal plant, to suggest the possible use of the stems for medicinal purposes. We studied the variation in the chemical composition in the stems and the rhizomes by employing four different extraction methods; the methanolic-, non-polar-, alkaloidal- and Total Tertiary Alkaloidal (TTA) to extract compounds from Cissampelos capensis. Employing various chromatographic techniques, HPLC, NMR and LC/MS to investigate the chemical variation and the in vitro assays for the crude materials of the stems and rhizomes of Cissampelos capensis. We successfully documented a library of the phytochemicals content in Cissampelos capensis from three different regions in the Eastern Cape. We could profile different extraction methods, with the TTA extraction delivering the best comparative profile. Employing LC/MS and HPLC we identified eleven known alkaloidal compounds in the stems and rhizomes. We also isolated a known alkaloid, pronuciferine, from the TTA extract and a crystal structure of proto-quericitol from the methanolic extract, which was isolated for the first time from Cissampelos capensis. Preliminary in vitro results suggested anti-inflammatory activity in the methanolic extracts of the stems and rhizomes, while the TTA extracts showed some cytotoxicity. Finally, through analytical HPLC analysis this study found as high as 31% similarity between the chemical variation of the stems and rhizomes, but key alkaloids were not always present, indicating more work is needed before the stems can be recommended as a replacement for the rhizomes.
- Full Text:
- Date Issued: 2017
- Authors: Latolla, Nehemiah Solomon
- Date: 2017
- Subjects: Plants -- Composition Medicinal plants Endemic plants
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13970 , vital:27362
- Description: Cissampelos capensis L. f. (Menispermaceae) commonly known as “Mayisake” (Xhosa) and “Dawidjieswortel” (Afrikaans) is the most commonly used medicinal plant of the Menispermaceae family in South Africa. The rhizomes of Cissampelos capensis are the most used part of the plant to treat illnesses. This poses a threat to the ongoing conservation of this valuable endemic species. Thus, we studied the chemical variation and subsequently the bioactivity in the stems and rhizomes of Cissampelos capensis, the Eastern Cape medicinal plant, to suggest the possible use of the stems for medicinal purposes. We studied the variation in the chemical composition in the stems and the rhizomes by employing four different extraction methods; the methanolic-, non-polar-, alkaloidal- and Total Tertiary Alkaloidal (TTA) to extract compounds from Cissampelos capensis. Employing various chromatographic techniques, HPLC, NMR and LC/MS to investigate the chemical variation and the in vitro assays for the crude materials of the stems and rhizomes of Cissampelos capensis. We successfully documented a library of the phytochemicals content in Cissampelos capensis from three different regions in the Eastern Cape. We could profile different extraction methods, with the TTA extraction delivering the best comparative profile. Employing LC/MS and HPLC we identified eleven known alkaloidal compounds in the stems and rhizomes. We also isolated a known alkaloid, pronuciferine, from the TTA extract and a crystal structure of proto-quericitol from the methanolic extract, which was isolated for the first time from Cissampelos capensis. Preliminary in vitro results suggested anti-inflammatory activity in the methanolic extracts of the stems and rhizomes, while the TTA extracts showed some cytotoxicity. Finally, through analytical HPLC analysis this study found as high as 31% similarity between the chemical variation of the stems and rhizomes, but key alkaloids were not always present, indicating more work is needed before the stems can be recommended as a replacement for the rhizomes.
- Full Text:
- Date Issued: 2017
The investigation of groundwater potential zones in the Neotectonic area of Ntabankulu Local Municipality, Eastern Cape Province, South Africa
- Nonkula, Zenande https://orcid.org/0000-0002-3858-7703
- Authors: Nonkula, Zenande https://orcid.org/0000-0002-3858-7703
- Date: 2021-09
- Subjects: Groundwater , Water-supply , Neotectonics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22875 , vital:53068
- Description: Ntabankulu extends from latitude 30° 51' 09"S to 31° 09' 10" S and from longitude 29° 06' 51"E to 29° 23' 49"E in the Eastern Cape Province of South Africa. Ntabankulu Local Municipality has 141 villages with 125 976 population size. About 36% of villages do not have water sources, 38% have partial functional water sources, 6% have non-functional water sources, and 20 % have reliable water sources, primarily rivers (Mnceba, Caba and Mzimvubu). Water is scarce in this area, especially in the dry season when perennial rivers and springs become dry. This research investigates groundwater potential zones and identifies suitable aquifers that can be developed to augment the water resources. The study involved: literature review, remote sensing, borehole and springs data, geological, petrographic and geophysical (gravity, magnetic and electrical resistivity) analyses. Each method has its purpose in finding the potential groundwater zones. Ntabankulu Local Municipality is located on the Karoo Supergroup in Ecca and Beaufort Group, Adelaide Subgroup and Balfour Formation. During field analysis, it was observed that this area consists of sandstone, shale and dolerite sills, dykes and complex rings. Fining up sequences, massive bedding, concretions, and spheroidal weathering were observed in sandstone, shale, and dolerite, respectively. Groundwater seepages are found within these structures. Sandstones are yellow due to the presence of limonite because of the continuous seepage. Red coloured laminated shale reflects that the rock has an iron oxidation state with hematite (Fe2O3) on the sediments. The Geographical Information Systems (GIS) method was used to extract lineaments. Lineaments dominate Ntabankulu with an NW-SE direction. Some of the lineaments are due to Karoo igneous intrusions, and others are due to neotectonic activities. Ntabankulu is located on the eastern and northern neotectonic belts. Geological maps and lineament maps were compared; it was observed that sandstones and shales are found on high liinament density areas. High yielding boreholes and springs coincide with lineaments, and some lineaments are faults. Hence areas that have high lineaments density could be groundwater potential zones. There are geological structures (faults, joints, and fractures) that are present. Systematic and non-systematic joints are found on sandstones which are due to extensional stress. These joints have been reactivated and acted as strike-slip faults. All these geological structures increase the porosity and permeability of the rocks. It was observed that the area of Ntabankulu consists of coarse-grained and medium-grained sandstone with quartz and orthoclase minerals. Dolerite consists of labradorite, clinopyroxene, olivine, oxide minerals with twinning formed during cooling and magma crystallisation. The gravity and magnetic methods were used to study the subsurface rock density contrasts and susceptibilities, respectively. The gravity and magnetic maps were generated in Geosoft Oasis 8.3 software. High gravity zones coincide with some of the mapped Karoo intrusions. Unmapped dolerite intrusions, lineaments and faults were inferred. The magnetic method delineated the subsurface structures (lineaments and faults), which are known to control groundwater accumulation. These structures and inferred dolerite intrusions helped in identifying groundwater potential zones. Groundwater potential zones were inferred in sedimentary rocks between dolerite intrusions and areas where sills and dykes intersect. A total of six vertical electrical soundings (VES) were conducted at Mzalwaneni and Tabankulu town areas using the Schlumberger configuration array with a maximum penetration depth of about 25- 33 m. The VES data were modelled in Winresist and Surfer 9 software to obtain 1D models and geoelectric sections, respectively. These 1D models have three layers with response curves of H-type. The top layer is about 0.4 - 0.7 m thick, with resistivity values from 12.3 – 1885.9 Ωm and is topsoil (sand and clay). The second layer of thickness 5.2 – 13.3 m has low resistivity values from 23.1- 44.9 Ωm. This layer is interpreted to be fractured shales and sandstones possibly containing water. The third layer of high resistivity values of 145.9 – 727.4 Ωm is inferred to be sandstone. The simultaneous interpretation of resistivity and normalised chargeability revealed that groundwater potential zones are characterised by low resistivity values and low normalised chargeability values for layers from 0.7 - 13.3 m depth. The groundwatwer in the area of Ntabankulu can be found on unconfined aquifers. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Nonkula, Zenande https://orcid.org/0000-0002-3858-7703
- Date: 2021-09
- Subjects: Groundwater , Water-supply , Neotectonics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22875 , vital:53068
- Description: Ntabankulu extends from latitude 30° 51' 09"S to 31° 09' 10" S and from longitude 29° 06' 51"E to 29° 23' 49"E in the Eastern Cape Province of South Africa. Ntabankulu Local Municipality has 141 villages with 125 976 population size. About 36% of villages do not have water sources, 38% have partial functional water sources, 6% have non-functional water sources, and 20 % have reliable water sources, primarily rivers (Mnceba, Caba and Mzimvubu). Water is scarce in this area, especially in the dry season when perennial rivers and springs become dry. This research investigates groundwater potential zones and identifies suitable aquifers that can be developed to augment the water resources. The study involved: literature review, remote sensing, borehole and springs data, geological, petrographic and geophysical (gravity, magnetic and electrical resistivity) analyses. Each method has its purpose in finding the potential groundwater zones. Ntabankulu Local Municipality is located on the Karoo Supergroup in Ecca and Beaufort Group, Adelaide Subgroup and Balfour Formation. During field analysis, it was observed that this area consists of sandstone, shale and dolerite sills, dykes and complex rings. Fining up sequences, massive bedding, concretions, and spheroidal weathering were observed in sandstone, shale, and dolerite, respectively. Groundwater seepages are found within these structures. Sandstones are yellow due to the presence of limonite because of the continuous seepage. Red coloured laminated shale reflects that the rock has an iron oxidation state with hematite (Fe2O3) on the sediments. The Geographical Information Systems (GIS) method was used to extract lineaments. Lineaments dominate Ntabankulu with an NW-SE direction. Some of the lineaments are due to Karoo igneous intrusions, and others are due to neotectonic activities. Ntabankulu is located on the eastern and northern neotectonic belts. Geological maps and lineament maps were compared; it was observed that sandstones and shales are found on high liinament density areas. High yielding boreholes and springs coincide with lineaments, and some lineaments are faults. Hence areas that have high lineaments density could be groundwater potential zones. There are geological structures (faults, joints, and fractures) that are present. Systematic and non-systematic joints are found on sandstones which are due to extensional stress. These joints have been reactivated and acted as strike-slip faults. All these geological structures increase the porosity and permeability of the rocks. It was observed that the area of Ntabankulu consists of coarse-grained and medium-grained sandstone with quartz and orthoclase minerals. Dolerite consists of labradorite, clinopyroxene, olivine, oxide minerals with twinning formed during cooling and magma crystallisation. The gravity and magnetic methods were used to study the subsurface rock density contrasts and susceptibilities, respectively. The gravity and magnetic maps were generated in Geosoft Oasis 8.3 software. High gravity zones coincide with some of the mapped Karoo intrusions. Unmapped dolerite intrusions, lineaments and faults were inferred. The magnetic method delineated the subsurface structures (lineaments and faults), which are known to control groundwater accumulation. These structures and inferred dolerite intrusions helped in identifying groundwater potential zones. Groundwater potential zones were inferred in sedimentary rocks between dolerite intrusions and areas where sills and dykes intersect. A total of six vertical electrical soundings (VES) were conducted at Mzalwaneni and Tabankulu town areas using the Schlumberger configuration array with a maximum penetration depth of about 25- 33 m. The VES data were modelled in Winresist and Surfer 9 software to obtain 1D models and geoelectric sections, respectively. These 1D models have three layers with response curves of H-type. The top layer is about 0.4 - 0.7 m thick, with resistivity values from 12.3 – 1885.9 Ωm and is topsoil (sand and clay). The second layer of thickness 5.2 – 13.3 m has low resistivity values from 23.1- 44.9 Ωm. This layer is interpreted to be fractured shales and sandstones possibly containing water. The third layer of high resistivity values of 145.9 – 727.4 Ωm is inferred to be sandstone. The simultaneous interpretation of resistivity and normalised chargeability revealed that groundwater potential zones are characterised by low resistivity values and low normalised chargeability values for layers from 0.7 - 13.3 m depth. The groundwatwer in the area of Ntabankulu can be found on unconfined aquifers. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
The investigation of in vitro dark cytotoxicity and photodynamic therapy effect of a 2, 6-dibromo-3, 5-distyryl BODIPY dye encapsulated in Pluronic® F-127 micelles
- Molupe, Nthabeleng, Babu, Balaji, Oluwole, David O, Prinsloo, Earl, Mack, John, Nyokong, Tebello
- Authors: Molupe, Nthabeleng , Babu, Balaji , Oluwole, David O , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187862 , vital:44704 , xlink:href="https://doi.org/10.1080/00958972.2018.1522536"
- Description: A 2,6-dibrominated 3,5-distyryl boron-dipyrromethene (BODIPY) dye with a moderately high singlet oxygen quantum yield was encapsulated in Pluronic® F-127 micelles, and its dark cytotoxicity and photodynamic activity were investigated on the human breast adenocarcinoma MCF-7 cell line. The BODIPY dye exhibited very low dark toxicity and a significant PDT effect when added in drug formulations consisting of 5.0% (v/v) DMSO in supplemented Dulbecco’s modified Eagle’s medium (DMEM) and as Pluronic® F-127 micelle encapsulation complexes in supplemented DMEM alone. An IC50 value of 4 ± 2 μM was obtained when the BODIPY dye was encapsulated in Pluronic® F-127 micelles during in vitro photodynamic activity studies in MCF-7 cancer cells with a 660 nm light emitting diode.
- Full Text:
- Date Issued: 2018
- Authors: Molupe, Nthabeleng , Babu, Balaji , Oluwole, David O , Prinsloo, Earl , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187862 , vital:44704 , xlink:href="https://doi.org/10.1080/00958972.2018.1522536"
- Description: A 2,6-dibrominated 3,5-distyryl boron-dipyrromethene (BODIPY) dye with a moderately high singlet oxygen quantum yield was encapsulated in Pluronic® F-127 micelles, and its dark cytotoxicity and photodynamic activity were investigated on the human breast adenocarcinoma MCF-7 cell line. The BODIPY dye exhibited very low dark toxicity and a significant PDT effect when added in drug formulations consisting of 5.0% (v/v) DMSO in supplemented Dulbecco’s modified Eagle’s medium (DMEM) and as Pluronic® F-127 micelle encapsulation complexes in supplemented DMEM alone. An IC50 value of 4 ± 2 μM was obtained when the BODIPY dye was encapsulated in Pluronic® F-127 micelles during in vitro photodynamic activity studies in MCF-7 cancer cells with a 660 nm light emitting diode.
- Full Text:
- Date Issued: 2018
The investigation of novel marine microorganisms for the production of biologically active metabolites
- Authors: Sunkel, Vanessa Ann
- Date: 2009 , 2013-07-15
- Subjects: Antibiotics , Drugs -- Research , Metabolites , Marine biotechnology , Marine metabolites -- Therapeutic use , Microorganisms -- Effect of drugs on , Penicillium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3812 , http://hdl.handle.net/10962/d1004579 , Antibiotics , Drugs -- Research , Metabolites , Marine biotechnology , Marine metabolites -- Therapeutic use , Microorganisms -- Effect of drugs on , Penicillium
- Description: New drugs, particularly antibiotics, are urgently required to combat the increasing problem of antibiotic resistant human pathogens. Due to the scarcity of products available today, the pharmaceutical industry is now under pressure to reassess compounds derived from plants, soil and marine organisms. Pharmaceutical companies are showing renewed interest in marine biotechnology as the oceans represent a rich source of both biological and chemical diversity of novel molecular structures with anti-cancer, anti-inflammatory and antibiotic properties. Formerly unexplored locations, such as deep ocean sediments, show great potential as a source of genetically novel microorganisms producing structurally unique secondary metabolites. In this research, a metabolite producing marine Pseudoalteromonas strain, known as AP5, was initially used to develop methods for the detection, optimisation of production and extraction of bioactive metabolites from other potentially novel marine isolates. Two hundred and seventy six (276) marine isolates from water and sediment samples from the Antarctic Ocean and Marion Island were isolated. Ten visually different isolates were screened for bioactivity against Gram-positive and -negative bacteria, fungi and yeast. Three out of the 10 isolates, WL61 , WL 114 and WL 136, appeared to be novel Streptomyces spp. showing activity against different test organisms. Many of these marine microorganisms are difficult to culture in the laboratory, particularly when they are cultivated continuously in shake flasks as they can stop producing bioactive compounds. The cultivation of marine isolates in bioreactors may be a more beneficial process for the optimisation of metabolite production compared to conventional liquid fermentation techniques whereby the solid-liquid-air interface of membrane bioreactors can imitate the natural environment of microbes. The membrane bioreactor system is a stable growth environment with low shear that supports steady-state biofilm growth consisting of a high cell density due to a high mass transfer of nutrients and oxygen to the cells. This approach was employed and isolates WL61, WL114 and WL136 were immobilised onto ceramic membranes using Quorus single fibre bioreactors (SFR). The SFRs were used to establish the most suitable growth medium for continuous secondary metabolite production. The best growth conditions were applied to the Quorus multifibre bioreactor (MFR) for scale up of biologically active metabolites, highlighting the potential of bioreactor technology for use in bioprospecting for isolating and screening novel and known organisms for new and interesting natural products. Furthermore, the Quorus MFR was shown to be suitable for the production of high yields of antimicrobial metabolites and is an efficient new fermentation production system. Purification by HPLC fractionation was used to characterise four major compounds from isolate WL 114 extracts. NMR structure elucidation identified one of the two primary compounds as Bisphenol A. The complete chemical structure for the second potent bioactive compound could not be determined due to the low concentration and volume of material. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2009
- Authors: Sunkel, Vanessa Ann
- Date: 2009 , 2013-07-15
- Subjects: Antibiotics , Drugs -- Research , Metabolites , Marine biotechnology , Marine metabolites -- Therapeutic use , Microorganisms -- Effect of drugs on , Penicillium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3812 , http://hdl.handle.net/10962/d1004579 , Antibiotics , Drugs -- Research , Metabolites , Marine biotechnology , Marine metabolites -- Therapeutic use , Microorganisms -- Effect of drugs on , Penicillium
- Description: New drugs, particularly antibiotics, are urgently required to combat the increasing problem of antibiotic resistant human pathogens. Due to the scarcity of products available today, the pharmaceutical industry is now under pressure to reassess compounds derived from plants, soil and marine organisms. Pharmaceutical companies are showing renewed interest in marine biotechnology as the oceans represent a rich source of both biological and chemical diversity of novel molecular structures with anti-cancer, anti-inflammatory and antibiotic properties. Formerly unexplored locations, such as deep ocean sediments, show great potential as a source of genetically novel microorganisms producing structurally unique secondary metabolites. In this research, a metabolite producing marine Pseudoalteromonas strain, known as AP5, was initially used to develop methods for the detection, optimisation of production and extraction of bioactive metabolites from other potentially novel marine isolates. Two hundred and seventy six (276) marine isolates from water and sediment samples from the Antarctic Ocean and Marion Island were isolated. Ten visually different isolates were screened for bioactivity against Gram-positive and -negative bacteria, fungi and yeast. Three out of the 10 isolates, WL61 , WL 114 and WL 136, appeared to be novel Streptomyces spp. showing activity against different test organisms. Many of these marine microorganisms are difficult to culture in the laboratory, particularly when they are cultivated continuously in shake flasks as they can stop producing bioactive compounds. The cultivation of marine isolates in bioreactors may be a more beneficial process for the optimisation of metabolite production compared to conventional liquid fermentation techniques whereby the solid-liquid-air interface of membrane bioreactors can imitate the natural environment of microbes. The membrane bioreactor system is a stable growth environment with low shear that supports steady-state biofilm growth consisting of a high cell density due to a high mass transfer of nutrients and oxygen to the cells. This approach was employed and isolates WL61, WL114 and WL136 were immobilised onto ceramic membranes using Quorus single fibre bioreactors (SFR). The SFRs were used to establish the most suitable growth medium for continuous secondary metabolite production. The best growth conditions were applied to the Quorus multifibre bioreactor (MFR) for scale up of biologically active metabolites, highlighting the potential of bioreactor technology for use in bioprospecting for isolating and screening novel and known organisms for new and interesting natural products. Furthermore, the Quorus MFR was shown to be suitable for the production of high yields of antimicrobial metabolites and is an efficient new fermentation production system. Purification by HPLC fractionation was used to characterise four major compounds from isolate WL 114 extracts. NMR structure elucidation identified one of the two primary compounds as Bisphenol A. The complete chemical structure for the second potent bioactive compound could not be determined due to the low concentration and volume of material. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2009
The investigation of perceptions of professional nurses regarding care of mental health care users in a general hospital setting
- Manona-Nkanjeni, Nonkanyiso Yvonne
- Authors: Manona-Nkanjeni, Nonkanyiso Yvonne
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Nursing Science)
- Identifier: vital:11924 , http://hdl.handle.net/10353/d1020200
- Description: This study sought to explore the perceptions of professional nurses regarding care of stabilised mental health care users in a general hospital setting. A qualitative, explanatory, descriptive and contextual design was used for the study. A non-probability, purposive sampling method was used to select 12 participants from the Cecilia Makiwane Hospital in Mdantsane. Data were collected through semi-structured interviews. The services of an independent interviewer were used to avoid any bias as interviews took place where the researcher is employed. The services of an editor were also used for language control (see Annexure H). The researcher repeatedly listened to the tapes used for data collection until completely satisfied with the interpretation of verbatim data. The research study was conducted in an ethically reflective manner and trustworthiness was ensured at all times. Four themes emerged from the analysis of the interviews: fear, stigma, myths and training. The researcher utilised the services of an independent coder who verified the identified major themes. The findings revealed that participants were fearful due to lack of knowledge, experience and psychiatric nursing skills. Participants feared because they lack knowledge about psychiatric medication and because mental health care users may have relapse. The participants also attached a stigma to mental health care users, which resulted in poor communication between participants and the stabilised mental health care user; a negative attitude towards mental health care users; and non-acceptance. Participants believed in myths about mental illness; they regarded it as contagious; and perceived mental health care users as dangerous. The participants strongly recommended that training should be provided to improve their knowledge and skills to enable them to care for stabilised mental health care users in a general hospital setting. The following should be facilitated: in-service training; adoption of a positive attitude; dispersal of myths and fear; education about referral systems; and allocation of specialist psychiatric nurses to medical wards for referral purposes with regard to complicated cases.
- Full Text:
- Date Issued: 2015
- Authors: Manona-Nkanjeni, Nonkanyiso Yvonne
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Nursing Science)
- Identifier: vital:11924 , http://hdl.handle.net/10353/d1020200
- Description: This study sought to explore the perceptions of professional nurses regarding care of stabilised mental health care users in a general hospital setting. A qualitative, explanatory, descriptive and contextual design was used for the study. A non-probability, purposive sampling method was used to select 12 participants from the Cecilia Makiwane Hospital in Mdantsane. Data were collected through semi-structured interviews. The services of an independent interviewer were used to avoid any bias as interviews took place where the researcher is employed. The services of an editor were also used for language control (see Annexure H). The researcher repeatedly listened to the tapes used for data collection until completely satisfied with the interpretation of verbatim data. The research study was conducted in an ethically reflective manner and trustworthiness was ensured at all times. Four themes emerged from the analysis of the interviews: fear, stigma, myths and training. The researcher utilised the services of an independent coder who verified the identified major themes. The findings revealed that participants were fearful due to lack of knowledge, experience and psychiatric nursing skills. Participants feared because they lack knowledge about psychiatric medication and because mental health care users may have relapse. The participants also attached a stigma to mental health care users, which resulted in poor communication between participants and the stabilised mental health care user; a negative attitude towards mental health care users; and non-acceptance. Participants believed in myths about mental illness; they regarded it as contagious; and perceived mental health care users as dangerous. The participants strongly recommended that training should be provided to improve their knowledge and skills to enable them to care for stabilised mental health care users in a general hospital setting. The following should be facilitated: in-service training; adoption of a positive attitude; dispersal of myths and fear; education about referral systems; and allocation of specialist psychiatric nurses to medical wards for referral purposes with regard to complicated cases.
- Full Text:
- Date Issued: 2015
The investigation of the hydrolysis reaction of m-phenylene to resorcinol
- Authors: Khaile, Thebeeapelo John
- Date: 2002
- Subjects: Resorcinol
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10961 , http://hdl.handle.net/10948/107 , Resorcinol
- Description: The purpose of this study was to characterise the resinous material formed during the acid catalysed hydrolysis of m-phenylenediamine (MPDA) to resorcinol, and to establish a reaction mechanism that could explain the formation of both resorcinol and the resinous materials in the reaction. A further objective was to determine reaction conditions that would lead to reduced formation of the resins during the hydrolysis reaction. The number of compounds present in a sample taken during the course of the hydrolysis reaction was determined by HPLC fitted with a photodiode array detector. Five main components were detected. These compounds were identified as mphenylenediamine, m-aminophenol, resorcinol, 3,3’-aminodiphenylamine and 3- amino-3’-hydroxydiphenylamine by means of GC-MS. 3,3’-Diaminodiphenylamine is formed by self-condensation of MPDA and 3-amino-3’-hydroxydiphenylamine is formed by the reaction of MPDA with resorcinol. The degree of formation of these intermediates is substantially reduced when MPDA is added dose-wise to phosphoric acid at a reaction temperature of 220oC. The reaction mechanism of the hydrolysis reaction was investigated by isotopic lable incorporation, followed by analysis by NMR. This was done by hydrolysing MPDA using deuterated phosphoric acid (D3PO4). D3PO4 was generated by dissolving phosphorus pentoxide in deuterium oxide. The resorcinol product obtained from the hydrolysis using D3PO4 was found to be deuterated on the C-2, C-4 and C-6 positions. This suggests that the hydrolysis reaction involves protonation of MPDA on these positions, and this results in the formation of an iminium ion as one of the resonance forms. Hydrolysis then occurs on the positively charged carbon of this species. Fertiliser grade phosphoric acid can be used in the hydrolysis reaction, provided sulphates are removed before the acid is used in the hydrolysis reaction. The hydrolysis reaction using either ammonium sulphate or sulphuric acid produces resorcinol in yields lower than 60% if the hydrolysis is conducted in one pass. If these catalysts are used in the hydrolysis reaction, the reaction mixture needs to be re-heated after removal of resorcinol in order to increase the yield. Hydrolysis of MPDA using zirconium phosphate as catalyst gave resorcinol yields in excess of 90% over 24 hours. These reactions were carried out at very low concentrations of MPDA (0.3%). The mode of catalysis in these reactions is unclear. There is a possibility that the reaction is catalysed by phosphoric acid that leaches out of zirconium phosphate at high temperatures. The reaction might therefore not differ mechanistically from the phosphoric acid catalysed reaction. Further studies are required to clarify this point.
- Full Text:
- Date Issued: 2002
- Authors: Khaile, Thebeeapelo John
- Date: 2002
- Subjects: Resorcinol
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10961 , http://hdl.handle.net/10948/107 , Resorcinol
- Description: The purpose of this study was to characterise the resinous material formed during the acid catalysed hydrolysis of m-phenylenediamine (MPDA) to resorcinol, and to establish a reaction mechanism that could explain the formation of both resorcinol and the resinous materials in the reaction. A further objective was to determine reaction conditions that would lead to reduced formation of the resins during the hydrolysis reaction. The number of compounds present in a sample taken during the course of the hydrolysis reaction was determined by HPLC fitted with a photodiode array detector. Five main components were detected. These compounds were identified as mphenylenediamine, m-aminophenol, resorcinol, 3,3’-aminodiphenylamine and 3- amino-3’-hydroxydiphenylamine by means of GC-MS. 3,3’-Diaminodiphenylamine is formed by self-condensation of MPDA and 3-amino-3’-hydroxydiphenylamine is formed by the reaction of MPDA with resorcinol. The degree of formation of these intermediates is substantially reduced when MPDA is added dose-wise to phosphoric acid at a reaction temperature of 220oC. The reaction mechanism of the hydrolysis reaction was investigated by isotopic lable incorporation, followed by analysis by NMR. This was done by hydrolysing MPDA using deuterated phosphoric acid (D3PO4). D3PO4 was generated by dissolving phosphorus pentoxide in deuterium oxide. The resorcinol product obtained from the hydrolysis using D3PO4 was found to be deuterated on the C-2, C-4 and C-6 positions. This suggests that the hydrolysis reaction involves protonation of MPDA on these positions, and this results in the formation of an iminium ion as one of the resonance forms. Hydrolysis then occurs on the positively charged carbon of this species. Fertiliser grade phosphoric acid can be used in the hydrolysis reaction, provided sulphates are removed before the acid is used in the hydrolysis reaction. The hydrolysis reaction using either ammonium sulphate or sulphuric acid produces resorcinol in yields lower than 60% if the hydrolysis is conducted in one pass. If these catalysts are used in the hydrolysis reaction, the reaction mixture needs to be re-heated after removal of resorcinol in order to increase the yield. Hydrolysis of MPDA using zirconium phosphate as catalyst gave resorcinol yields in excess of 90% over 24 hours. These reactions were carried out at very low concentrations of MPDA (0.3%). The mode of catalysis in these reactions is unclear. There is a possibility that the reaction is catalysed by phosphoric acid that leaches out of zirconium phosphate at high temperatures. The reaction might therefore not differ mechanistically from the phosphoric acid catalysed reaction. Further studies are required to clarify this point.
- Full Text:
- Date Issued: 2002
The investigation of the impact of household contractor project in Ukhahlamba District since 2003 with regards to poverty alleviation among the participating household contractors
- Authors: Ngwendu, Mandlenkosi Victor
- Date: 2010
- Subjects: Economic assistance, Domestic -- South Africa -- Eastern Cape , Poverty -- Governmentpolicy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9060 , http://hdl.handle.net/10948/1396 , Economic assistance, Domestic -- South Africa -- Eastern Cape , Poverty -- Governmentpolicy -- South Africa -- Eastern Cape
- Description: This study investigates impact made by Household Contractor Project as a Poverty Alleviation initiative on participating Household Contractors in Ukhahlamba in the Eastern Cape Province. Household Contractor Project is an Expanded Public Works Project implemented by the Eastern Cape Provincial Government to achieve the following EPWP principles, namely: Poverty alleviation; Creation of employment opportunities and; Creation of opportunities for skills development. The project (meaning Household Contractor Project) is implemented in the Province's six districts, namely: Alfred Nzo, Amathole, Cacadu, Chris Hani, O.R. Tambo, and Ukhahlamba. The study aims at investigating whether Household Contractor Project in Ukhahlamba district has resulted in poverty alleviation among participating household contractors. The study uses measurable indicators like food security, education for children, health needs and basic household needs to achieve its aim.
- Full Text:
- Date Issued: 2010
- Authors: Ngwendu, Mandlenkosi Victor
- Date: 2010
- Subjects: Economic assistance, Domestic -- South Africa -- Eastern Cape , Poverty -- Governmentpolicy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9060 , http://hdl.handle.net/10948/1396 , Economic assistance, Domestic -- South Africa -- Eastern Cape , Poverty -- Governmentpolicy -- South Africa -- Eastern Cape
- Description: This study investigates impact made by Household Contractor Project as a Poverty Alleviation initiative on participating Household Contractors in Ukhahlamba in the Eastern Cape Province. Household Contractor Project is an Expanded Public Works Project implemented by the Eastern Cape Provincial Government to achieve the following EPWP principles, namely: Poverty alleviation; Creation of employment opportunities and; Creation of opportunities for skills development. The project (meaning Household Contractor Project) is implemented in the Province's six districts, namely: Alfred Nzo, Amathole, Cacadu, Chris Hani, O.R. Tambo, and Ukhahlamba. The study aims at investigating whether Household Contractor Project in Ukhahlamba district has resulted in poverty alleviation among participating household contractors. The study uses measurable indicators like food security, education for children, health needs and basic household needs to achieve its aim.
- Full Text:
- Date Issued: 2010
The investigation of the role and the efficacy of learning technologies towards community skill development
- Authors: Masikisiki, Baphumelele
- Date: 2017
- Subjects: Web-based instruction Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5972 , vital:29460
- Description: Research has revealed that during systems design and development of e-learning technologies there is a tendency of neglecting the needs of end users and focus on the design process and the technology factors, and this has traditionally been the reason for poor usability of otherwise well conceptualized systems, as a result a number of IT-based learning tools ended up not being usable and not being utilized effectively. This study aims to investigate the impact of e-learning technologies, how people perceive the usage of e-learning technologies towards community skill development. An evaluation of four different e-learning technologies was conducted to investigate the role and efficacy of e-learning technologies within the surrounding communities. Data was analyzed as nominal data using IBM Statistical Package for Social Sciences (SPSS) software 24. Descriptive analysis, frequency, reliability and correctional analysis and also measures of central tendency were computed. Reliability was evaluated for assessing the internal consistency of the items using Cronbach’s alpha. To analyze the relationship between variables matrices of Pearson’s correlation was used. Pearson’s correlation can only be accepted when the significant effect (P>.05), this indicates that there is a positive or a negative relationship between two variables, if these conditions are not met then the proposed correlation or hypothesis can be rejected. Results indicate a poor perception and poor acceptance of e-learning technologies due to a number of factors, these factors include lack of computer-self efficacy which leads to computer anxiety, affordability of internet connectivity which leads to inaccessible of e-learning technologies. The findings also indicated that LAMS was found to be less useable and less useful by a number of students. However, students who enjoy working in groups found LAMS to be useable because it was supporting their preferred learning style, whereas individualistic students preferred Moodle and Dokeos because it was supporting their personal preferences and assessment styles. Having understood all the characteristics of learning tools, relevant learning technologies that are suitable for students can then be recommended.
- Full Text:
- Date Issued: 2017
- Authors: Masikisiki, Baphumelele
- Date: 2017
- Subjects: Web-based instruction Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5972 , vital:29460
- Description: Research has revealed that during systems design and development of e-learning technologies there is a tendency of neglecting the needs of end users and focus on the design process and the technology factors, and this has traditionally been the reason for poor usability of otherwise well conceptualized systems, as a result a number of IT-based learning tools ended up not being usable and not being utilized effectively. This study aims to investigate the impact of e-learning technologies, how people perceive the usage of e-learning technologies towards community skill development. An evaluation of four different e-learning technologies was conducted to investigate the role and efficacy of e-learning technologies within the surrounding communities. Data was analyzed as nominal data using IBM Statistical Package for Social Sciences (SPSS) software 24. Descriptive analysis, frequency, reliability and correctional analysis and also measures of central tendency were computed. Reliability was evaluated for assessing the internal consistency of the items using Cronbach’s alpha. To analyze the relationship between variables matrices of Pearson’s correlation was used. Pearson’s correlation can only be accepted when the significant effect (P>.05), this indicates that there is a positive or a negative relationship between two variables, if these conditions are not met then the proposed correlation or hypothesis can be rejected. Results indicate a poor perception and poor acceptance of e-learning technologies due to a number of factors, these factors include lack of computer-self efficacy which leads to computer anxiety, affordability of internet connectivity which leads to inaccessible of e-learning technologies. The findings also indicated that LAMS was found to be less useable and less useful by a number of students. However, students who enjoy working in groups found LAMS to be useable because it was supporting their preferred learning style, whereas individualistic students preferred Moodle and Dokeos because it was supporting their personal preferences and assessment styles. Having understood all the characteristics of learning tools, relevant learning technologies that are suitable for students can then be recommended.
- Full Text:
- Date Issued: 2017
The investigation of type-specific features of the copper coordinating AA9 proteins and their effect on the interaction with crystalline cellulose using molecular dynamics studies
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018