Carbon credit restoration projects in the Eastern Cape province of South Africa: considerations for sustainable local economic development
- Authors: Polak, James Samuel
- Date: 2017
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/8069 , vital:21349
- Description: Although global climate change has been identified as a serious global economic, social, and environmental threat to society, national governments have been slow to respond on a global scale. Environmental economic theory offers market-based solutions to address climate change efficiently through carbon control regimes, such as carbon taxation and cap-and-trade policy. A major political milestone was reached when an international agreement entered into force in 2008, known the Kyoto Protocol, which incorporated a market-based solution to address climate change on a global scale. This allowed a global market for emissions to form through the Clean Development Mechanism. Although the Kyoto Protocol aimed to address a global issue on a global scale through a single global market for emissions, fragmented sovereign cap-and-trade schemes have since emerged in the form of national and regional emission markets, commonly referred to as carbon markets. The Clean Development Mechanism offered the opportunity to generate carbon credits through carbon offset projects, such as carbon restoration projects. Although the Kyoto Protocol did not achieve the objective of forming an internationally accepted global carbon control regime, it seems to have set a trend of including offset programs in newly emerging carbon control regimes, such as South Africa’s proposed carbon tax. This study set out to assess the extent to which carbon control regimes are enabling sustainable local economic development, based on carbon restoration projects in the Eastern Cape province of South Africa using Portulacaria afra, commonly known as spekboom. As a starting point, this study assessed the current state of the international carbon markets using significant international cap-and-trade based markets as examples. Based on Newell et al.’s (2013) selection of significant carbon markets and data availability, the United States’ Regional Greenhouse Gas Initiative and the European Union’s Emission Trading Scheme were selected. Historical, current and forecasted supply and demand data were gathered from Thomson Reuters’ Point Carbon research division. Further, historical futures and spot market price and volume data were gathered from the markets to compare how prices have fared over time. The Clean Development Mechanism’s market for Certified Emission Reduction credits was used for comparative purposes. The markets were found to be systemically oversupplied, leading to systemically low prices. The systemic oversupply in credits provides a limited incentive to initiate carbon offset projects, however, South Africa’s proposed carbon tax may be able to stimulate demand for domestic offset projects. Key success factors established through a comparative literature review on local economic development theory were incorporated into key informant interviews. The results were then analysed through the lens of Connelly’s (2007) model for sustainable development to provide recommendations for sustainable local economic development, regarding carbon restoration projects in the Eastern Cape using P. afra. The following opportunities were identified: the planting of P. afra on degraded land has the potential to mitigate climate change, offer water benefits to the surrounding communities, and promote biodiversity regeneration. There is potential for economic growth through job creation and the economic multiplier effect. Government funding is available and voluntary offset agreements do exist, eliminating a large portion of the cumbersome accreditation requirements. These projects also offer potential for social justice through the government funding requirements which stipulate that youth and women should be given preference for employment, potentially helping to alleviate inequality. The funding further stipulates that employees should be trained in transferable skills, offering potential for capacity building and social capital accumulation through education. These transferable skills include skills geared towards encouraging entrepreneurialism. Corresponding challenges were also found: excessive overgrazing through pastoralism has rendered some land degraded beyond restoration. Opportunists may resort to planting P. afra outside of the subtropical Albany Thicket biome to which it is endemic, leading to potential biodiversity loss rather than gains. Sufficient buy-in is required from private landowners for these projects to be sustainable, however, the projects entail a large opportunity cost to farmers as returns take at least 5 to 6 years. This may render these projects undesirable to most landowners and provides scope for free-riding, should pastoralists not have to bear the full costs of the project and property rights not be enforced through land user agreements. The projects require an exorbitant amount of upfront funding. Cash flow received from the projects does not extend in perpetuity. Requirements for social justice pertain only to government funded projects. A working model, generating and selling carbon credits through land restoration using P. afra, has not yet been established. As it stands, these carbon restoration projects are still highly speculative and carry a significant amount of investment risk, given the high mortality and low growth rates associated with the current planting method. The current systemic oversupply of carbon. credits in the international markets signal that returns from carbon credits are set to be low, at least until the oversupply issues are resolved. Should these challenges be overcome, carbon restoration projects using P. afra may have the potential to bolster sustainable local economic development in the impoverished regions of province as well as provide a locally-driven adaptation and mitigation strategy to address global climate change.
- Full Text:
- Authors: Polak, James Samuel
- Date: 2017
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/8069 , vital:21349
- Description: Although global climate change has been identified as a serious global economic, social, and environmental threat to society, national governments have been slow to respond on a global scale. Environmental economic theory offers market-based solutions to address climate change efficiently through carbon control regimes, such as carbon taxation and cap-and-trade policy. A major political milestone was reached when an international agreement entered into force in 2008, known the Kyoto Protocol, which incorporated a market-based solution to address climate change on a global scale. This allowed a global market for emissions to form through the Clean Development Mechanism. Although the Kyoto Protocol aimed to address a global issue on a global scale through a single global market for emissions, fragmented sovereign cap-and-trade schemes have since emerged in the form of national and regional emission markets, commonly referred to as carbon markets. The Clean Development Mechanism offered the opportunity to generate carbon credits through carbon offset projects, such as carbon restoration projects. Although the Kyoto Protocol did not achieve the objective of forming an internationally accepted global carbon control regime, it seems to have set a trend of including offset programs in newly emerging carbon control regimes, such as South Africa’s proposed carbon tax. This study set out to assess the extent to which carbon control regimes are enabling sustainable local economic development, based on carbon restoration projects in the Eastern Cape province of South Africa using Portulacaria afra, commonly known as spekboom. As a starting point, this study assessed the current state of the international carbon markets using significant international cap-and-trade based markets as examples. Based on Newell et al.’s (2013) selection of significant carbon markets and data availability, the United States’ Regional Greenhouse Gas Initiative and the European Union’s Emission Trading Scheme were selected. Historical, current and forecasted supply and demand data were gathered from Thomson Reuters’ Point Carbon research division. Further, historical futures and spot market price and volume data were gathered from the markets to compare how prices have fared over time. The Clean Development Mechanism’s market for Certified Emission Reduction credits was used for comparative purposes. The markets were found to be systemically oversupplied, leading to systemically low prices. The systemic oversupply in credits provides a limited incentive to initiate carbon offset projects, however, South Africa’s proposed carbon tax may be able to stimulate demand for domestic offset projects. Key success factors established through a comparative literature review on local economic development theory were incorporated into key informant interviews. The results were then analysed through the lens of Connelly’s (2007) model for sustainable development to provide recommendations for sustainable local economic development, regarding carbon restoration projects in the Eastern Cape using P. afra. The following opportunities were identified: the planting of P. afra on degraded land has the potential to mitigate climate change, offer water benefits to the surrounding communities, and promote biodiversity regeneration. There is potential for economic growth through job creation and the economic multiplier effect. Government funding is available and voluntary offset agreements do exist, eliminating a large portion of the cumbersome accreditation requirements. These projects also offer potential for social justice through the government funding requirements which stipulate that youth and women should be given preference for employment, potentially helping to alleviate inequality. The funding further stipulates that employees should be trained in transferable skills, offering potential for capacity building and social capital accumulation through education. These transferable skills include skills geared towards encouraging entrepreneurialism. Corresponding challenges were also found: excessive overgrazing through pastoralism has rendered some land degraded beyond restoration. Opportunists may resort to planting P. afra outside of the subtropical Albany Thicket biome to which it is endemic, leading to potential biodiversity loss rather than gains. Sufficient buy-in is required from private landowners for these projects to be sustainable, however, the projects entail a large opportunity cost to farmers as returns take at least 5 to 6 years. This may render these projects undesirable to most landowners and provides scope for free-riding, should pastoralists not have to bear the full costs of the project and property rights not be enforced through land user agreements. The projects require an exorbitant amount of upfront funding. Cash flow received from the projects does not extend in perpetuity. Requirements for social justice pertain only to government funded projects. A working model, generating and selling carbon credits through land restoration using P. afra, has not yet been established. As it stands, these carbon restoration projects are still highly speculative and carry a significant amount of investment risk, given the high mortality and low growth rates associated with the current planting method. The current systemic oversupply of carbon. credits in the international markets signal that returns from carbon credits are set to be low, at least until the oversupply issues are resolved. Should these challenges be overcome, carbon restoration projects using P. afra may have the potential to bolster sustainable local economic development in the impoverished regions of province as well as provide a locally-driven adaptation and mitigation strategy to address global climate change.
- Full Text:
Cardiovascular disease risk in Black and Caucasian females: an Eastern Cape sample
- Authors: Remsing, Sandra Claudia
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/40737 , vital:25021
- Description: The purpose of this study was to investigate cardiovascular disease risk in Black and Caucasian urban working females of the Makana region of the Eastern Cape. One- hundred and sixty six age-matched urban-working individuals (Black n = 88; Caucasian n = 78) voluntarily participated in this cross-sectional study. Cardiovascular disease risk was assessed in four categories: 1) obesity, classified as ‘morphological risk’, 2) blood pressure, classified as ‘cardiovascular risk’, 3) diet, physical activity, smoking, and alcohol consumption, classified as ‘lifestyle risk’, and 4) education and income, classified as ‘socioeconomic factors’. Results showed that Black females were significantly (p<0.01) heavier than Caucasian females and categorized as ‘obese’ according to BMI classifications (31.19 ± 8.09 kg.m2 and 25.90 ±4.67 kg.m2, respectively). Black females also presented with significantly (p<0.01) higher waist circumferences and waist-to-stature ratios, further confirming the obesity prevalence in this group. When accounting for those who were on anti-hypertensive mediation, Black females additionally presented with significantly (p<0.05) higher blood pressure, categorizing them as ‘pre-hypertensive’ (MAP = 98 ± 16 mmHg and 85 ± 11 mmHg, respectively). These results therefore placed Black females at increased cardiovascular disease risk compared to Caucasian females. With respect to lifestyle factors, Black females consumed significantly (p<0.05) more kilojoules carbohydrates, and total sugar than Caucasian females, and expended more physical activity MET- minutes per week (2688.86 ± 1486.56 MET-minutes and 1828.27 ± 2238.10 MET- minutes, respectively). However, reduced validity of physical activity data as well as poor dietary recall limited the interpretations of these findings. In addition, despite significant differences between smoking and alcohol consumption between groups, the majority of both Black and Caucasian females reported being non-smokers and consumed alcohol minimally. Thus, these were concluded to be unlikely contributors to cardiovascular disease risk in these samples. Socioeconomic results nevertheless expectedly showed that Black females were significantly (p<0.05) less educated, and subsequently earned lower incomes. It was thus concluded that this may be a likely contributor to higher cardiovascular risk in Black females. Future recommendations include the incorporation of exercise intensity measures as well as objective measures of habitual diet. This is in order to get a clearer understanding of the impact of these lifestyle factors on cardiovascular disease risk.
- Full Text:
- Authors: Remsing, Sandra Claudia
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/40737 , vital:25021
- Description: The purpose of this study was to investigate cardiovascular disease risk in Black and Caucasian urban working females of the Makana region of the Eastern Cape. One- hundred and sixty six age-matched urban-working individuals (Black n = 88; Caucasian n = 78) voluntarily participated in this cross-sectional study. Cardiovascular disease risk was assessed in four categories: 1) obesity, classified as ‘morphological risk’, 2) blood pressure, classified as ‘cardiovascular risk’, 3) diet, physical activity, smoking, and alcohol consumption, classified as ‘lifestyle risk’, and 4) education and income, classified as ‘socioeconomic factors’. Results showed that Black females were significantly (p<0.01) heavier than Caucasian females and categorized as ‘obese’ according to BMI classifications (31.19 ± 8.09 kg.m2 and 25.90 ±4.67 kg.m2, respectively). Black females also presented with significantly (p<0.01) higher waist circumferences and waist-to-stature ratios, further confirming the obesity prevalence in this group. When accounting for those who were on anti-hypertensive mediation, Black females additionally presented with significantly (p<0.05) higher blood pressure, categorizing them as ‘pre-hypertensive’ (MAP = 98 ± 16 mmHg and 85 ± 11 mmHg, respectively). These results therefore placed Black females at increased cardiovascular disease risk compared to Caucasian females. With respect to lifestyle factors, Black females consumed significantly (p<0.05) more kilojoules carbohydrates, and total sugar than Caucasian females, and expended more physical activity MET- minutes per week (2688.86 ± 1486.56 MET-minutes and 1828.27 ± 2238.10 MET- minutes, respectively). However, reduced validity of physical activity data as well as poor dietary recall limited the interpretations of these findings. In addition, despite significant differences between smoking and alcohol consumption between groups, the majority of both Black and Caucasian females reported being non-smokers and consumed alcohol minimally. Thus, these were concluded to be unlikely contributors to cardiovascular disease risk in these samples. Socioeconomic results nevertheless expectedly showed that Black females were significantly (p<0.05) less educated, and subsequently earned lower incomes. It was thus concluded that this may be a likely contributor to higher cardiovascular risk in Black females. Future recommendations include the incorporation of exercise intensity measures as well as objective measures of habitual diet. This is in order to get a clearer understanding of the impact of these lifestyle factors on cardiovascular disease risk.
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Cationic cyclodextrin/alginate chitosan nanoflowers as 5-fluorouracil drug delivery system
- Lakkakula, Jaya R, Matshaya, Thabo, Krause, Rui W M
- Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125587 , vital:35798 , https://doi.org/10.1016/j.msec.2016.08.073
- Description: Cyclodextrins (CDs) have widely been used as component of drug delivery systems. However unmodified cyclodextrins are associated with cytotoxicity and poor water solubility thus limiting their use in pharmaceutical industry. The cationic-β-cyclodextrin (Cat-β-CD) polymer cores were synthesized using β-CD, epichlorohydrin and choline chloride via a one-step polycondensation process. The main aim of this study was to synthesize hierarchical nanoflowers composed of cationic-β-CD as polymeric core along with alginate and chitosan “petals” (Cat-β-CD/Alg-Chi nanoflowers) as carriers for oral delivery of 5-Fluorouracil (5-FU) via an ionic-gelation technique. The drug loading capacity, particle size, zeta potential and surface morphology of the synthesized nanoflowers were determined. The prepared nanoflowers were formed with an average size of 300 nm and a zeta potential of + 9.90 mV with good encapsulation efficiency of up to 77.3%. In vitro release of 5-FU from the loaded nanoflowers showed controlled and sustained release compared to the inclusion complex alone. Cat-β-CD/Alg-Chi nanoflowers were assessed against L929 cells and found to be effectively inhibiting the growth of L929 cells in a concentration dependent manner.
- Full Text:
- Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125587 , vital:35798 , https://doi.org/10.1016/j.msec.2016.08.073
- Description: Cyclodextrins (CDs) have widely been used as component of drug delivery systems. However unmodified cyclodextrins are associated with cytotoxicity and poor water solubility thus limiting their use in pharmaceutical industry. The cationic-β-cyclodextrin (Cat-β-CD) polymer cores were synthesized using β-CD, epichlorohydrin and choline chloride via a one-step polycondensation process. The main aim of this study was to synthesize hierarchical nanoflowers composed of cationic-β-CD as polymeric core along with alginate and chitosan “petals” (Cat-β-CD/Alg-Chi nanoflowers) as carriers for oral delivery of 5-Fluorouracil (5-FU) via an ionic-gelation technique. The drug loading capacity, particle size, zeta potential and surface morphology of the synthesized nanoflowers were determined. The prepared nanoflowers were formed with an average size of 300 nm and a zeta potential of + 9.90 mV with good encapsulation efficiency of up to 77.3%. In vitro release of 5-FU from the loaded nanoflowers showed controlled and sustained release compared to the inclusion complex alone. Cat-β-CD/Alg-Chi nanoflowers were assessed against L929 cells and found to be effectively inhibiting the growth of L929 cells in a concentration dependent manner.
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Challenges with modelling transcription factor binding
- Machanick, Philip, Kibet, Caleb K
- Authors: Machanick, Philip , Kibet, Caleb K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439158 , vital:73551 , 10.1109/NEXTCOMP.2017.8016178
- Description: Modelling transcription factor binding presents a number of challenges. In its simplest form, binding can be modelled by a consensus sequence but a number of factors including degeneracy of binding sites, alternative modes of binding and differences between artificially-constructed and in vivo DNA make modelling binding complex. In this paper we outline difficulties and report on progress with improving modelling of binding. We focus on improving measurement of binding models, a necessary prerequisite for finding better models.
- Full Text:
- Authors: Machanick, Philip , Kibet, Caleb K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439158 , vital:73551 , 10.1109/NEXTCOMP.2017.8016178
- Description: Modelling transcription factor binding presents a number of challenges. In its simplest form, binding can be modelled by a consensus sequence but a number of factors including degeneracy of binding sites, alternative modes of binding and differences between artificially-constructed and in vivo DNA make modelling binding complex. In this paper we outline difficulties and report on progress with improving modelling of binding. We focus on improving measurement of binding models, a necessary prerequisite for finding better models.
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Change Drivers at the front lines of the future: rising cultures for sustainability education in contemporary South Africa
- Authors: Kulundu, Injairu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437107 , vital:73331 , ISBN 978-0-620-79605-7 , https://doi.org/10.3920/978-90-8686-846-9_33
- Description: This chapter asks us to regenerate and re-imagine what a dis-tinctively young and contemporary feeling of Environmental and Sustainability Education could look like in the African con-text. It asks us to acknowledge the ingenious ways that Change Drivers in South Africa and Africa are moving towards their visions of the common good. The chapter invites us to trace and learn from the transgressive learning and nomadic journeys of young Change Drivers who are part of a network called Activate! Change Drivers. Activate! Change Drivers is one of the largest youth led movements in South Africa. It is a network of young leaders equipped to drive change for the common good in South Africa. In a world that is uncertain and unknown the embodied knowledge of Change Drivers in South Africa can help us as practitioners think carefully and critically about how to learn for an unknown and predominantly young future.
- Full Text:
- Authors: Kulundu, Injairu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437107 , vital:73331 , ISBN 978-0-620-79605-7 , https://doi.org/10.3920/978-90-8686-846-9_33
- Description: This chapter asks us to regenerate and re-imagine what a dis-tinctively young and contemporary feeling of Environmental and Sustainability Education could look like in the African con-text. It asks us to acknowledge the ingenious ways that Change Drivers in South Africa and Africa are moving towards their visions of the common good. The chapter invites us to trace and learn from the transgressive learning and nomadic journeys of young Change Drivers who are part of a network called Activate! Change Drivers. Activate! Change Drivers is one of the largest youth led movements in South Africa. It is a network of young leaders equipped to drive change for the common good in South Africa. In a world that is uncertain and unknown the embodied knowledge of Change Drivers in South Africa can help us as practitioners think carefully and critically about how to learn for an unknown and predominantly young future.
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Changes in chemical composition of essential oils from leaves of different Lantana camara L. (Verbenaceae) varieties after feeding by the introduced biological control agent, Falconia intermedia Distant (Hemiptera: Miridae)
- Ngxande-Koza, Samella W, Heshula, Lelethu U P, Hill, Martin P
- Authors: Ngxande-Koza, Samella W , Heshula, Lelethu U P , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59834 , vital:27664 , https://doi.org/10.4001/003.025.0462
- Description: Lantana camara L. (Verbenaceae) is one of the most problematic plant invaders in South Africa and has been targeted for biological control for over 50 years. Essential oil constituents which often change in response to insect herbivory are reported to play a crucial role in plant-insect interactions. However, nothing is known about the chemical profiles of essential oils of L. camara varieties in South Africa and how this changes under herbivory. Therefore, essential oils were collected using hydrodistillation from undamaged and insect-damaged leaves of four L. camara varieties and analysed using gas chromatography-mass spectrometry to elucidate their chemical profiles. A total of 163 compounds were identified from the undamaged leaves of the various L. camara varieties. Feeding by the biocontrol agent Falconia intermedia Distant (Hemiptera: Miridae) resulted in changes in the quality and quantity of chemical constituents of the essential oils. Only 75 compounds were identified from the insect-damaged leaves of L. camara varieties. Terpenes were the major components across the varieties, while caryophyllene, hexane, naphthalene, copaene and a-caryophyllene were common in all the varieties tested from both undamaged and insect-damaged leaves. Results from this study indicated the chemical distinctiveness of the Whitney Farm variety from other varieties. The changes in chemical concentrations indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. These inductions following the feeding by F. intermedia could be having a negative impact on the success of biological control against L. camara varieties. However, the focus of this paper is to report on the chemical baseline of L. camara varieties. Hence, comparisons of chemical compound concentrations of L. camara essential oils tested and the feeding-induced changes with respect to their quality and quantity are discussed.
- Full Text:
- Authors: Ngxande-Koza, Samella W , Heshula, Lelethu U P , Hill, Martin P
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59834 , vital:27664 , https://doi.org/10.4001/003.025.0462
- Description: Lantana camara L. (Verbenaceae) is one of the most problematic plant invaders in South Africa and has been targeted for biological control for over 50 years. Essential oil constituents which often change in response to insect herbivory are reported to play a crucial role in plant-insect interactions. However, nothing is known about the chemical profiles of essential oils of L. camara varieties in South Africa and how this changes under herbivory. Therefore, essential oils were collected using hydrodistillation from undamaged and insect-damaged leaves of four L. camara varieties and analysed using gas chromatography-mass spectrometry to elucidate their chemical profiles. A total of 163 compounds were identified from the undamaged leaves of the various L. camara varieties. Feeding by the biocontrol agent Falconia intermedia Distant (Hemiptera: Miridae) resulted in changes in the quality and quantity of chemical constituents of the essential oils. Only 75 compounds were identified from the insect-damaged leaves of L. camara varieties. Terpenes were the major components across the varieties, while caryophyllene, hexane, naphthalene, copaene and a-caryophyllene were common in all the varieties tested from both undamaged and insect-damaged leaves. Results from this study indicated the chemical distinctiveness of the Whitney Farm variety from other varieties. The changes in chemical concentrations indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. These inductions following the feeding by F. intermedia could be having a negative impact on the success of biological control against L. camara varieties. However, the focus of this paper is to report on the chemical baseline of L. camara varieties. Hence, comparisons of chemical compound concentrations of L. camara essential oils tested and the feeding-induced changes with respect to their quality and quantity are discussed.
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Changes in forest cover and carbon stocks of the coastal scarp forests of the Wild Coast, South Africa
- Mangwale, Kagiso, Shackleton, Charlie M, Sigwela, Ayanda
- Authors: Mangwale, Kagiso , Shackleton, Charlie M , Sigwela, Ayanda
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60903 , vital:27887 , https://doi.org/10.2989/20702620.2016.1255480
- Description: Land-use intensification and declines in vegetative cover are considered pervasive threats to forests and biodiversity globally. The small extent and high biodiversity of indigenous forests in South Africa make them particularly important. Yet, relatively little is known about their rates of use and change. From analysis of past aerial photos we quantified rates of forest cover change in the Matiwane forests of the Wild Coast, South Africa, between 1942 and 2007, as well as quantified above- and belowground (to 0.5 m depth) carbon stocks based on a composite allometric equation derived for the area. Rates of forest conversion were spatially variable, with some areas showing no change and others more noticeable changes. Overall, the net reduction was 5.2% (0.08% p.a.) over the 65-year period. However, the rate of reduction has accelerated with time. Some of the reduction was balanced by natural reforestation into formerly cleared areas, but basal area, biomass and carbon stocks are still low in the reforested areas. The total carbon stock was highest in intact forests (311.7 ± 23.7 Mg C ha−1), followed by degraded forests (73.5 ± 12.3 Mg C ha−1) and least in regrowth forests (51.2 ± 6.2 Mg C ha−1). The greatest contribution to total carbon stocks was soil carbon, contributing 54% in intact forests, and 78% and 68% in degraded and regrowth forests, respectively. The Matiwane forests store 4.78 Tg C, with 4.7 Tg C in intact forests, 0.06 Tg C in degraded forests and 0.02 Tg C in regrowth forests. The decrease in carbon stocks within the forests as a result of the conversion of the forest area to agricultural fields was 0.19 Tg C and approximately 0.0003 Tg C was released through harvesting of firewood and building timber.
- Full Text:
- Authors: Mangwale, Kagiso , Shackleton, Charlie M , Sigwela, Ayanda
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60903 , vital:27887 , https://doi.org/10.2989/20702620.2016.1255480
- Description: Land-use intensification and declines in vegetative cover are considered pervasive threats to forests and biodiversity globally. The small extent and high biodiversity of indigenous forests in South Africa make them particularly important. Yet, relatively little is known about their rates of use and change. From analysis of past aerial photos we quantified rates of forest cover change in the Matiwane forests of the Wild Coast, South Africa, between 1942 and 2007, as well as quantified above- and belowground (to 0.5 m depth) carbon stocks based on a composite allometric equation derived for the area. Rates of forest conversion were spatially variable, with some areas showing no change and others more noticeable changes. Overall, the net reduction was 5.2% (0.08% p.a.) over the 65-year period. However, the rate of reduction has accelerated with time. Some of the reduction was balanced by natural reforestation into formerly cleared areas, but basal area, biomass and carbon stocks are still low in the reforested areas. The total carbon stock was highest in intact forests (311.7 ± 23.7 Mg C ha−1), followed by degraded forests (73.5 ± 12.3 Mg C ha−1) and least in regrowth forests (51.2 ± 6.2 Mg C ha−1). The greatest contribution to total carbon stocks was soil carbon, contributing 54% in intact forests, and 78% and 68% in degraded and regrowth forests, respectively. The Matiwane forests store 4.78 Tg C, with 4.7 Tg C in intact forests, 0.06 Tg C in degraded forests and 0.02 Tg C in regrowth forests. The decrease in carbon stocks within the forests as a result of the conversion of the forest area to agricultural fields was 0.19 Tg C and approximately 0.0003 Tg C was released through harvesting of firewood and building timber.
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Changes in household food security, nutrition and food waste along an agro-ecological gradient and the rural-urban continuum in mid-sized South African towns
- Authors: Chakona, Gamuchirai
- Date: 2017
- Subjects: Food security -- South Africa , Women -- South Africa -- Nutritiona , Urban women -- South Africa -- Nutrition , Rural women -- South Africa -- Nutrition , Wild foods -- South Africa , Food supply -- South Africa , Malnutrition in children -- South Africa , Grants-in-aid -- South Africa , Household ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6484 , vital:21127
- Description: The lack of dietary diversity is a severe problem experienced by most poor households globally. Most poor communities are at high risk of inadequate intake of micronutrients resulting from diets dominated by starchy staples. The present study considered the diets, dietary diversities and food security of women of reproductive age between 15-49 years, households and communities along the rural-urban continuum in three mid-sized towns situated along an agro-ecological gradient in South Africa. A 48-hour dietary recall was performed across two seasons (twice in summer and once in winter) and focus group discussions were held to gather all information including food abundance, seasons of food scarcity as well as coping strategies which households employ during periods of food shocks. Households were further asked to quantify any type of food waste that they could have generated in the previous 48 hours. Nutritional status of children under the age of five in all three towns was also measured using height-for-age (HAZ) and mid-upper arm circumference (MUAC) as indicators of stunting and wasting respectively. The household surveys were conducted with 554 women randomly selected in rural, peri-urban and urban locations of Richards Bay, Dundee and Harrismith. For nutritional status, the sample consisted of 216 children who were randomly selected from the sampled households in rural, peri-urban and urban locations of the study sites. Household Dietary Diversity Scores (HDDS) and Women’s Dietary Diversity Scores (WDDS) were calculated from the food items consumed by each household and each woman over a two-day period, respectively. Household food access was also measured for each household using Household Food Insecurity Access Scale (HFIAS). The mean WDDS and HDDS for the wettest site of Richards Bay (3.8±0.29 and 8.44±1.72, respectively) was significantly higher than at Dundee (3.4±0.30 and 7.76±1.63, respectively) and Harrismith (3.5±0.27 and 7.83±1.59, respectively) which were not different from one another. The mean HFIAS for Dundee (9.39±7.13) was significantly higher than that in Richards Bay (5.57±6.98) and Harrismith (6.43±6.59) which were not significantly different from one another. Dietary diversity scores were also significantly higher in urban locations than in peri-urban and rural ones whilst HFIAS was significantly lower in the urban locations than peri-urban and rural locations. There was lower dependence on food purchasing in Richards Bay compared to Dundee and Harrismith where the majority of the population was purchasing most of their food. The majority of Richards Bay households were involved in subsistence agriculture and also produced a surplus for sale, as well as collecting wild foods, which improved food security, unlike Dundee and Harrismith. Food insecurity was higher in rural and peri-urban areas compared to urban areas. In all towns, food was always available throughout the year but was beyond the reach of many households. In urban areas food was readily available and only limited by access, whereas rural populations have limited access to affordable food and face higher prices. The peri-urban populations were more food insecure because of high levels of poverty, unemployment and lack of access/entitlements to land. Periurban dwellers are therefore more sensitive to changes in incomes and food prices because they lack safety nets to absorb income or price shocks as they purchase more, rather than growing their own food. Household dietary diversity was significantly negatively correlated with household food access, that is households with low HDDS had higher HFIAS scores. Due to high levels of food insecurity, a greater percentage of children under the age of five years were stunted (35 %) and wasted (18 %). There were no significant differences in stunting along the agro-ecological gradient, along the rural-urban continuum and sex of child. However, significant differences were observed in child wasting along the agro-ecological gradient with Harrismith having more wasted children than the other two towns, which were not significantly different from each other. Significant differences were also observed between MUAC and sex of child where male children had higher MUAC than females. Wasting was significantly negatively associated with HDDS, with children from households with low HDDS tending to have large MUAC thus showing an inverse association among HDDS and obesity. However, further studies are needed to confirm this finding. In general food insecurity was closely associated with low wealth, food expenditure, large household size and limited access to land. The study did not find any significant role in the use of wild foods and social grants in improving food security for those households who were consuming wild foods and those receiving social grants. Although a greater percentage of households were food insecure, significant amounts of unprepared food (495±179 g per household) were wasted in Richards Bay alone in 48 hours mainly because the food had passed the best before date or had visibly gone bad. The amount of food waste was closely significantly negatively associated with household size. In general, the prevalence of food insecurity and wasting followed the agro-ecological gradient, with households in Richards Bay where the area.
- Full Text:
- Authors: Chakona, Gamuchirai
- Date: 2017
- Subjects: Food security -- South Africa , Women -- South Africa -- Nutritiona , Urban women -- South Africa -- Nutrition , Rural women -- South Africa -- Nutrition , Wild foods -- South Africa , Food supply -- South Africa , Malnutrition in children -- South Africa , Grants-in-aid -- South Africa , Household ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6484 , vital:21127
- Description: The lack of dietary diversity is a severe problem experienced by most poor households globally. Most poor communities are at high risk of inadequate intake of micronutrients resulting from diets dominated by starchy staples. The present study considered the diets, dietary diversities and food security of women of reproductive age between 15-49 years, households and communities along the rural-urban continuum in three mid-sized towns situated along an agro-ecological gradient in South Africa. A 48-hour dietary recall was performed across two seasons (twice in summer and once in winter) and focus group discussions were held to gather all information including food abundance, seasons of food scarcity as well as coping strategies which households employ during periods of food shocks. Households were further asked to quantify any type of food waste that they could have generated in the previous 48 hours. Nutritional status of children under the age of five in all three towns was also measured using height-for-age (HAZ) and mid-upper arm circumference (MUAC) as indicators of stunting and wasting respectively. The household surveys were conducted with 554 women randomly selected in rural, peri-urban and urban locations of Richards Bay, Dundee and Harrismith. For nutritional status, the sample consisted of 216 children who were randomly selected from the sampled households in rural, peri-urban and urban locations of the study sites. Household Dietary Diversity Scores (HDDS) and Women’s Dietary Diversity Scores (WDDS) were calculated from the food items consumed by each household and each woman over a two-day period, respectively. Household food access was also measured for each household using Household Food Insecurity Access Scale (HFIAS). The mean WDDS and HDDS for the wettest site of Richards Bay (3.8±0.29 and 8.44±1.72, respectively) was significantly higher than at Dundee (3.4±0.30 and 7.76±1.63, respectively) and Harrismith (3.5±0.27 and 7.83±1.59, respectively) which were not different from one another. The mean HFIAS for Dundee (9.39±7.13) was significantly higher than that in Richards Bay (5.57±6.98) and Harrismith (6.43±6.59) which were not significantly different from one another. Dietary diversity scores were also significantly higher in urban locations than in peri-urban and rural ones whilst HFIAS was significantly lower in the urban locations than peri-urban and rural locations. There was lower dependence on food purchasing in Richards Bay compared to Dundee and Harrismith where the majority of the population was purchasing most of their food. The majority of Richards Bay households were involved in subsistence agriculture and also produced a surplus for sale, as well as collecting wild foods, which improved food security, unlike Dundee and Harrismith. Food insecurity was higher in rural and peri-urban areas compared to urban areas. In all towns, food was always available throughout the year but was beyond the reach of many households. In urban areas food was readily available and only limited by access, whereas rural populations have limited access to affordable food and face higher prices. The peri-urban populations were more food insecure because of high levels of poverty, unemployment and lack of access/entitlements to land. Periurban dwellers are therefore more sensitive to changes in incomes and food prices because they lack safety nets to absorb income or price shocks as they purchase more, rather than growing their own food. Household dietary diversity was significantly negatively correlated with household food access, that is households with low HDDS had higher HFIAS scores. Due to high levels of food insecurity, a greater percentage of children under the age of five years were stunted (35 %) and wasted (18 %). There were no significant differences in stunting along the agro-ecological gradient, along the rural-urban continuum and sex of child. However, significant differences were observed in child wasting along the agro-ecological gradient with Harrismith having more wasted children than the other two towns, which were not significantly different from each other. Significant differences were also observed between MUAC and sex of child where male children had higher MUAC than females. Wasting was significantly negatively associated with HDDS, with children from households with low HDDS tending to have large MUAC thus showing an inverse association among HDDS and obesity. However, further studies are needed to confirm this finding. In general food insecurity was closely associated with low wealth, food expenditure, large household size and limited access to land. The study did not find any significant role in the use of wild foods and social grants in improving food security for those households who were consuming wild foods and those receiving social grants. Although a greater percentage of households were food insecure, significant amounts of unprepared food (495±179 g per household) were wasted in Richards Bay alone in 48 hours mainly because the food had passed the best before date or had visibly gone bad. The amount of food waste was closely significantly negatively associated with household size. In general, the prevalence of food insecurity and wasting followed the agro-ecological gradient, with households in Richards Bay where the area.
- Full Text:
Chapter one: Founding and establishing an imperial university: the first twenty-five years
- Authors: Maylam, Paul
- Date: 2017
- Subjects: Rhodes University -- History , Rhodes Unviersity , Universities and colleges -- South Africa -- Grahamstown
- Language: English
- Type: book , text
- Identifier: http://hdl.handle.net/10962/59896 , vital:27689
- Description: Critics of South Africa's Truth and Reconciliation Commission (TRC) that sat in the late 1990s have sometimes pointed to its failure to examine the role of larger collectivities in colluding with or acquiescing in the apartheid system. Universities, for instance, have been singled out for their failure both to make submissions to the TRC and to acknowledge openly their past shortcomings during the apartheid era. The historically white, English-medium universities – among them Rhodes University – liked to project themselves as liberal institutions. This book puts this self-representation to the test by looking critically at the operation and functioning of Rhodes University during the segregation and apartheid eras. This study is one of very few that recounts and analyses the whole history of a South African university in a single volume. It covers the founding of Rhodes University College (as it was then called) in 1904, traces its development over the decades, through the attainment of independent status in 1951, ending with a full consideration of the transformation challenges that the university has faced in the post-apartheid era. This is a critical study that points to some of the university’s past failures. But there is also a celebratory dimension, as the book highlights some of the achievements and successes of those who have worked and studied at Rhodes University over the past 112 or so years. , Please note that only the first chapter of the book is available online. For further information, or should you wish to purchase a copy of this item, please contact Bulelani Mothlabane (b.mothlabaneATru.ac.za).
- Full Text:
- Authors: Maylam, Paul
- Date: 2017
- Subjects: Rhodes University -- History , Rhodes Unviersity , Universities and colleges -- South Africa -- Grahamstown
- Language: English
- Type: book , text
- Identifier: http://hdl.handle.net/10962/59896 , vital:27689
- Description: Critics of South Africa's Truth and Reconciliation Commission (TRC) that sat in the late 1990s have sometimes pointed to its failure to examine the role of larger collectivities in colluding with or acquiescing in the apartheid system. Universities, for instance, have been singled out for their failure both to make submissions to the TRC and to acknowledge openly their past shortcomings during the apartheid era. The historically white, English-medium universities – among them Rhodes University – liked to project themselves as liberal institutions. This book puts this self-representation to the test by looking critically at the operation and functioning of Rhodes University during the segregation and apartheid eras. This study is one of very few that recounts and analyses the whole history of a South African university in a single volume. It covers the founding of Rhodes University College (as it was then called) in 1904, traces its development over the decades, through the attainment of independent status in 1951, ending with a full consideration of the transformation challenges that the university has faced in the post-apartheid era. This is a critical study that points to some of the university’s past failures. But there is also a celebratory dimension, as the book highlights some of the achievements and successes of those who have worked and studied at Rhodes University over the past 112 or so years. , Please note that only the first chapter of the book is available online. For further information, or should you wish to purchase a copy of this item, please contact Bulelani Mothlabane (b.mothlabaneATru.ac.za).
- Full Text:
Characterisation, antimalarial and biological activities of secondary metabolites from leaves of anonidium mannii
- Authors: Makoni, Pfungwa Gervase
- Date: 2017
- Subjects: Anonidium mannii -- Therapeutic use , Botanical chemistry , Annonaceae -- Therapeutic use , Apocynaceae -- Therapeutic use , Malaria -- Chemotherapy , Tuberculosis -- Chemotherapy , Bacterial diseases -- Chemotherapy , Cancer -- Chemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4797 , vital:20725
- Description: Anonidium mannii is a plant of the Annonaceae genus which is used traditionally in Africa for the treatment of gonorrhoea, malaria, cancer, skin inflammation and dysentery. In this study we will evaluate antimalarial, antifungal, anti - tuberculosis, antibacterial activities and cytotoxicity of different fractions in order to provide a scientific rationale for the traditional use of Anonidium mannii as well as provide possible novel drugs in the treatment of multi drug resistant strains of parasites and bacteria. Extracts from dried leaves were obtained by using solvent extraction and different fractions obtained using column chromatography eluted with solvents of varying polarities to obtain a wide range of metabolites. The antimalarial activity of the various fractions and some pure compounds was evaluated using plasmodium lactate dehydrogenase (pLDH) assay. Cytotoxicity was evaluated using HeLa cells while anti – tuberculosis assay was evaluated using the green fluorescent protein. Antibacterial activity of the extracts was evaluated using micro-dilution assay against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria and Gram-negative (Escherichia coli and Salmonella typhi) bacteria. Antifungal activity was evaluated against Candida albicans. The antimalarial assays yielded some fractions with promising IC50 values. The selected fractions yielded activities ranging between 0.73 μg/mL and 20.23 μg/mL. The fraction with the best activity was obtained from a hexane/ethyl acetate fraction. AM1C, a cholestane, showed the best activity from the pure metabolites that were screened. AM3C, stigmasterol, a pure compound gave the best antifungal activity with an MIC of 0.063 μg/mL. AM9C another pure compound (sterol) showed the best activity against S. typhi with a value of 0.031 μg/mL. AM2C a pure compound showed an activity of 0.063 μg/mL against E. faecalis. The best cytotoxicity was demonstrated by the fraction C2AM3P with a cell viability of 7.1 ± 0.2 % while AM1C had a viability of 20.2 ± 1.2 %. Several pure metabolites were isolated and four of these were positively identified as steroids. Of these steroids the structure of three novel metabolites from A. mannii was deduced. The study showed promising antibacterial, antifungal, anti – tuberculosis, antimalarial and anticancer activity of A. mannii. These results validate the use of A. manni against cancer, skin inflammation which is caused by fungus, malaria and bacterial diseases.
- Full Text:
- Authors: Makoni, Pfungwa Gervase
- Date: 2017
- Subjects: Anonidium mannii -- Therapeutic use , Botanical chemistry , Annonaceae -- Therapeutic use , Apocynaceae -- Therapeutic use , Malaria -- Chemotherapy , Tuberculosis -- Chemotherapy , Bacterial diseases -- Chemotherapy , Cancer -- Chemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4797 , vital:20725
- Description: Anonidium mannii is a plant of the Annonaceae genus which is used traditionally in Africa for the treatment of gonorrhoea, malaria, cancer, skin inflammation and dysentery. In this study we will evaluate antimalarial, antifungal, anti - tuberculosis, antibacterial activities and cytotoxicity of different fractions in order to provide a scientific rationale for the traditional use of Anonidium mannii as well as provide possible novel drugs in the treatment of multi drug resistant strains of parasites and bacteria. Extracts from dried leaves were obtained by using solvent extraction and different fractions obtained using column chromatography eluted with solvents of varying polarities to obtain a wide range of metabolites. The antimalarial activity of the various fractions and some pure compounds was evaluated using plasmodium lactate dehydrogenase (pLDH) assay. Cytotoxicity was evaluated using HeLa cells while anti – tuberculosis assay was evaluated using the green fluorescent protein. Antibacterial activity of the extracts was evaluated using micro-dilution assay against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria and Gram-negative (Escherichia coli and Salmonella typhi) bacteria. Antifungal activity was evaluated against Candida albicans. The antimalarial assays yielded some fractions with promising IC50 values. The selected fractions yielded activities ranging between 0.73 μg/mL and 20.23 μg/mL. The fraction with the best activity was obtained from a hexane/ethyl acetate fraction. AM1C, a cholestane, showed the best activity from the pure metabolites that were screened. AM3C, stigmasterol, a pure compound gave the best antifungal activity with an MIC of 0.063 μg/mL. AM9C another pure compound (sterol) showed the best activity against S. typhi with a value of 0.031 μg/mL. AM2C a pure compound showed an activity of 0.063 μg/mL against E. faecalis. The best cytotoxicity was demonstrated by the fraction C2AM3P with a cell viability of 7.1 ± 0.2 % while AM1C had a viability of 20.2 ± 1.2 %. Several pure metabolites were isolated and four of these were positively identified as steroids. Of these steroids the structure of three novel metabolites from A. mannii was deduced. The study showed promising antibacterial, antifungal, anti – tuberculosis, antimalarial and anticancer activity of A. mannii. These results validate the use of A. manni against cancer, skin inflammation which is caused by fungus, malaria and bacterial diseases.
- Full Text:
Characterization and physicochemical studies of the conjugates of graphene quantum dots with differently charged zinc phthalocyanines
- Matshitse, Refilwe, Sekhosana, Kutloano E, Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Sekhosana, Kutloano E , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189227 , vital:44829 , xlink:href="https://doi.org/10.1080/00958972.2017.1387652"
- Description: Unsubstituted zinc phthalocyanine (ZnPc), 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ) and Zn tetrasulfo phthalocyanine (ZnTSPc) were non-covalently (electrostatic and/or π–π interaction) attached to graphene quantum dots (GQDs) to form GQDs-Pc nanoconjugates. Relative to Pcs alone, the presence of GQDs improved the triplet quantum yields with the following values: GQDs-ZnPc (0.73), GQDs-ZnTPPcQ (0.76) and GQDs-ZnTSPc (0.67). Respective Förster resonance energy transfer (FRET) efficiencies were calculated to be 0.81, 0.80 and 0.28. However, singlet oxygen generating abilities of the as-synthesized nanoconjugates were relatively low due to the screening effect of GQDs and quenching in water. This study shows that, the type of Pc, loading and solvent used are among the vital properties to consider when constructing GQD-nanoconjugate systems with optimal triplet quantum yield properties and investigation of their physicochemical properties.
- Full Text:
- Authors: Matshitse, Refilwe , Sekhosana, Kutloano E , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189227 , vital:44829 , xlink:href="https://doi.org/10.1080/00958972.2017.1387652"
- Description: Unsubstituted zinc phthalocyanine (ZnPc), 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ) and Zn tetrasulfo phthalocyanine (ZnTSPc) were non-covalently (electrostatic and/or π–π interaction) attached to graphene quantum dots (GQDs) to form GQDs-Pc nanoconjugates. Relative to Pcs alone, the presence of GQDs improved the triplet quantum yields with the following values: GQDs-ZnPc (0.73), GQDs-ZnTPPcQ (0.76) and GQDs-ZnTSPc (0.67). Respective Förster resonance energy transfer (FRET) efficiencies were calculated to be 0.81, 0.80 and 0.28. However, singlet oxygen generating abilities of the as-synthesized nanoconjugates were relatively low due to the screening effect of GQDs and quenching in water. This study shows that, the type of Pc, loading and solvent used are among the vital properties to consider when constructing GQD-nanoconjugate systems with optimal triplet quantum yield properties and investigation of their physicochemical properties.
- Full Text:
Characterization of conjugates of NaYF4
- Watkins, Zane, Uddin, Imran, Britton, Jonathan, Nyokong, Tebello
- Authors: Watkins, Zane , Uddin, Imran , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238132 , vital:50589 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.10.011"
- Description: NaYF4:Er/Yb/Gd upconversion nanoparticles (UCNP) capped with amino groups were covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). There was a decrease in the intensity of fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to Förster resonance energy transfer (FRET). FRET efficiencies of 18% and 21% for ClAlTSPc and ClAlTCPc, respectively, were obtained. Oxygen generation by ClAlTSPc following FRET was proved.
- Full Text:
- Authors: Watkins, Zane , Uddin, Imran , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238132 , vital:50589 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.10.011"
- Description: NaYF4:Er/Yb/Gd upconversion nanoparticles (UCNP) capped with amino groups were covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). There was a decrease in the intensity of fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to Förster resonance energy transfer (FRET). FRET efficiencies of 18% and 21% for ClAlTSPc and ClAlTCPc, respectively, were obtained. Oxygen generation by ClAlTSPc following FRET was proved.
- Full Text:
Characterization of phthalocyanine functionalized quantum dots by dynamic light scattering, laser Doppler, and capillary electrophoresis
- Ramírez-García, Gonzalo, Oluwole, David O, Nxele, Siphesihle Robin, d’Orlyé, Fanny, Nyokong, Tebello, Bedioui, Fethi, Varenne, Anne
- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
- Full Text:
- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
- Full Text:
Characterization of the distribution of platinum group elements in sulphide ores within the Merensky Reef at Modikwa and Two Rivers Platinum Mines, Eastern Bushveld Complex, South Africa
- Authors: Zilibokwe, Nosibulelo Julie
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7938 , vital:21326
- Description: The distribution of the platinum group element (PGE), in the Merensky Reef was characterized by, first determining the occurrence of the platinum group minerals (PGM), then by establishing the PGE concentration in the base metal sulphides (BMS) associated with the PGE mineralization in the Merensky Reef from selected borehole intersections, at the Two Rivers (TRP) and Modikwa Platinum Mines in the Eastern Bushveld Complex. A mineral liberation analyser (MLA) was then used to identify the PGM phases; their silicate and base metal associations; and their grain size distribution. Electron microprobe quantitative analysis and mapping were then used to determine the compositional variation of the PGM and the PGE elemental distribution in the BMS, respectively. The study showed that the BMS including pyrrhotite, pentlandite, and chalcopyrite were the principal sulphides, where pyrrhotite was most prominent with minor quantities of pyrite. Orthopyroxene, clinopyroxene and plagioclase were the most abundant primary silicate minerals identified, while secondary silicates identified included talc, serpentine and amphibole. Platinum group minerals showed three distinct groups with respect to the mineralogical association with the PGE; (i) BMS association; (ii) chromite association; and (iii) silicate association. Of the BMS, chalcopyrite showed the most dominant association with the PGMs. All samples from both mines exhibited a wide range of PGMs, including maslovite, braggite, cooperate, laurite and PGE alloys such as ferroplatinum as well as other unidentified platinum and palladium sulphides, arsenides and bismuthides, while gold was present as electrum. The PGMs ranged in size from less than a micron to about 125 microns with an average of 20 microns. The close association of PGM with BMS along the margins of sulphides indicates that the PGMs were derived from the sulphide melt. PGE distribution in the sulphides at Modikwa showed pentlandite contained the highest concentrations of palladium (up to 379 ppm) and chalcopyrite hosting the highest rhodium concentrations (up to 793 ppm). Samples from Two Rivers revealed pentlandite as the principal host to both palladium and rhodium, with concentrations reaching up to 695 and 930 ppm, respectively. Magnetite at both Modikwa and Two Rivers showed significant rhodium content, reaching up to 982 and 930 ppm, respectively. The pyrrhotite compared to other sulphides contained all the elements found in the platinum group (PPGE), namely, platinum, palladium and rhodium, with all the platinum identified found in the pyrrhotite. The concentrations for the iridium group (IPGE) namely, iridium, osmium, and ruthenium were below the detection limit. The PGE mineralization in the stratigraphy varied within each mine. The mineralization revealed top loading in the central sector (Modikwa) and bottom loading in the southern sector (Two Rivers). The sequence of the Merensky Reef at the two sectors of the Eastern Bushveld Complex showed a remarkable similarity in their mineralogy suggesting that these two sectors were formed from the same liquid or formed simultaneously within a single magma chamber; however the PGE distribution within the stratigraphy may have been controlled by the presence of cumulate sulphides.
- Full Text:
- Authors: Zilibokwe, Nosibulelo Julie
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7938 , vital:21326
- Description: The distribution of the platinum group element (PGE), in the Merensky Reef was characterized by, first determining the occurrence of the platinum group minerals (PGM), then by establishing the PGE concentration in the base metal sulphides (BMS) associated with the PGE mineralization in the Merensky Reef from selected borehole intersections, at the Two Rivers (TRP) and Modikwa Platinum Mines in the Eastern Bushveld Complex. A mineral liberation analyser (MLA) was then used to identify the PGM phases; their silicate and base metal associations; and their grain size distribution. Electron microprobe quantitative analysis and mapping were then used to determine the compositional variation of the PGM and the PGE elemental distribution in the BMS, respectively. The study showed that the BMS including pyrrhotite, pentlandite, and chalcopyrite were the principal sulphides, where pyrrhotite was most prominent with minor quantities of pyrite. Orthopyroxene, clinopyroxene and plagioclase were the most abundant primary silicate minerals identified, while secondary silicates identified included talc, serpentine and amphibole. Platinum group minerals showed three distinct groups with respect to the mineralogical association with the PGE; (i) BMS association; (ii) chromite association; and (iii) silicate association. Of the BMS, chalcopyrite showed the most dominant association with the PGMs. All samples from both mines exhibited a wide range of PGMs, including maslovite, braggite, cooperate, laurite and PGE alloys such as ferroplatinum as well as other unidentified platinum and palladium sulphides, arsenides and bismuthides, while gold was present as electrum. The PGMs ranged in size from less than a micron to about 125 microns with an average of 20 microns. The close association of PGM with BMS along the margins of sulphides indicates that the PGMs were derived from the sulphide melt. PGE distribution in the sulphides at Modikwa showed pentlandite contained the highest concentrations of palladium (up to 379 ppm) and chalcopyrite hosting the highest rhodium concentrations (up to 793 ppm). Samples from Two Rivers revealed pentlandite as the principal host to both palladium and rhodium, with concentrations reaching up to 695 and 930 ppm, respectively. Magnetite at both Modikwa and Two Rivers showed significant rhodium content, reaching up to 982 and 930 ppm, respectively. The pyrrhotite compared to other sulphides contained all the elements found in the platinum group (PPGE), namely, platinum, palladium and rhodium, with all the platinum identified found in the pyrrhotite. The concentrations for the iridium group (IPGE) namely, iridium, osmium, and ruthenium were below the detection limit. The PGE mineralization in the stratigraphy varied within each mine. The mineralization revealed top loading in the central sector (Modikwa) and bottom loading in the southern sector (Two Rivers). The sequence of the Merensky Reef at the two sectors of the Eastern Bushveld Complex showed a remarkable similarity in their mineralogy suggesting that these two sectors were formed from the same liquid or formed simultaneously within a single magma chamber; however the PGE distribution within the stratigraphy may have been controlled by the presence of cumulate sulphides.
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Characterization of the Mitochondrial Plasmodium falciparum heat shock protein 70
- Authors: Nyakundi, David Onchong’a
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44449 , vital:25408 , https://doi.org/10.21504/10962/44448
- Description: Malaria remains a global health problem and accounts for many deaths and illnesses in subSaharan Africa. Plasmodium falciparum, the causative agent of the most fatal form of malaria, expresses a repertoire of heat shock proteins for cytoprotection, survival and pathogenesis. The parasite genome encodes six Hsp70 proteins found in various cell compartments. However, the putative parasite mitochondrial Hsp70 (PfHsp70-3) has not been investigated. The J-proteins, Pfj1 and PFF1415c, were proposed to function as co-chaperones of PfHsp70-3. The biochemical characterization of PfHsp70-3 was initially complicated by the fact that the protein was insoluble when expressed in E. coli cells. Various approaches to solubilize it resulted in inactive protein. A general characteristic of eukaryotic mitochondrial Hsp70s is their insolubility and their reliance on an Hsp70 escort protein (Hep) for solubility and ultimate functions. In this study, a putative Hep protein was identified in the genome of P. falciparum that is referred to as PfHep1. Coexpression of PfHep1 with PfHsp70-3 resulted in soluble and biochemically active PfHsp70-3. Size exclusion chromatography was employed to separate PfHsp70-3 from PfHep1 after coexpression. PfHep1 suppressed thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were also found to be essential for maintaining the functions of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Furthermore, PfHep1 did not stimulate the basal ATPase or increase refoldase activities of PfHsp70-3 hence displaying no co-chaperone roles. The full-length putative mitochondrial type I J protein, Pfj1, could not be produced in E.coli but a truncated protein containing the J-domain was produced which stimulated both the ATPase and refoldase activities of PfHsp70-3. Further, this study demonstrated that both PfHep1 and PfHsp70-3 localized to the mitochondrion in the erythrocytic stage of P. falciparum development thus confirming in silico predictions of their localization. Besides, PfHsp70-3 was expressed during all stages of the intraerythrocytic cycle of parasite development and was heat inducible. Generally, the data obtained in this study will enhance the existing knowledge on the biology of the parasite mitochondrial chaperone functions and open the possible avenue of drug targeting considering the specificity of PfHsp70- 3 and PfHep1 partnerships.
- Full Text:
- Authors: Nyakundi, David Onchong’a
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44449 , vital:25408 , https://doi.org/10.21504/10962/44448
- Description: Malaria remains a global health problem and accounts for many deaths and illnesses in subSaharan Africa. Plasmodium falciparum, the causative agent of the most fatal form of malaria, expresses a repertoire of heat shock proteins for cytoprotection, survival and pathogenesis. The parasite genome encodes six Hsp70 proteins found in various cell compartments. However, the putative parasite mitochondrial Hsp70 (PfHsp70-3) has not been investigated. The J-proteins, Pfj1 and PFF1415c, were proposed to function as co-chaperones of PfHsp70-3. The biochemical characterization of PfHsp70-3 was initially complicated by the fact that the protein was insoluble when expressed in E. coli cells. Various approaches to solubilize it resulted in inactive protein. A general characteristic of eukaryotic mitochondrial Hsp70s is their insolubility and their reliance on an Hsp70 escort protein (Hep) for solubility and ultimate functions. In this study, a putative Hep protein was identified in the genome of P. falciparum that is referred to as PfHep1. Coexpression of PfHep1 with PfHsp70-3 resulted in soluble and biochemically active PfHsp70-3. Size exclusion chromatography was employed to separate PfHsp70-3 from PfHep1 after coexpression. PfHep1 suppressed thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were also found to be essential for maintaining the functions of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Furthermore, PfHep1 did not stimulate the basal ATPase or increase refoldase activities of PfHsp70-3 hence displaying no co-chaperone roles. The full-length putative mitochondrial type I J protein, Pfj1, could not be produced in E.coli but a truncated protein containing the J-domain was produced which stimulated both the ATPase and refoldase activities of PfHsp70-3. Further, this study demonstrated that both PfHep1 and PfHsp70-3 localized to the mitochondrion in the erythrocytic stage of P. falciparum development thus confirming in silico predictions of their localization. Besides, PfHsp70-3 was expressed during all stages of the intraerythrocytic cycle of parasite development and was heat inducible. Generally, the data obtained in this study will enhance the existing knowledge on the biology of the parasite mitochondrial chaperone functions and open the possible avenue of drug targeting considering the specificity of PfHsp70- 3 and PfHep1 partnerships.
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Chemical composition of leaf essential oils of Lantana camara varieties in South Africa and their effect on the behavioural preference of Falconia intermedia
- Authors: Ngxande-Koza, Samella W
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4877 , vital:20739
- Description: Lantana camara L. (Verbenaceae) is one the most problematic invaders in South Africa invading forest edges, sand dunes, and shorelines by forming impenetrable thickets. Lantana camara invasions degrade natural biodiversity, reduce the value of land and consequently it has been a target for biological control, over the last 50 years in South Africa. Studies that have reported on chemical profile of Lantana camara have been conducted around the world but not in South Africa. Hence, the first aim of the current study was to identify the chemical baseline of L. camara varieties in the Eastern Cape, South Africa. Recent studies have shown that feeding by one of the agents released against L. camara, Falconia intermedia (Distant) (Hemiptera: Miridae), induces anti-herbivory response through increased leaf toughness and trichome density. A preliminary study conducted also reported the production of volatile chemicals by one variety, Whitney Farm, due to feeding by the mirids. Therefore, the second aim was to determine the induced changes in chemical compounds of L. camara varieties after feeding by F. intermedia. A third aim was to determine the effect these chemical compounds have on the behaviour of F. intermedia. To identify the chemical baseline of L. camara varieties, the essential oils of four L. camara varieties (East London, Port Alfred, Whitney Farm and Heather Glen) were analysed using gas chromatography mass spectrometry (GC-MS) and that resulted to the identification of 163 constitutive and 75 induced chemicals across the varieties tested. Lantana camara varieties showed different chemical classes but were highly dominated by terpenes. A great variation in the number of constitutive chemical compounds was found in all the varieties. There were 56 constitutive chemical compounds in the Whitney Farm variety, 41 in the East London variety, 36 in the Heather Glen variety and 30 in the Port Alfred variety. The Whitney Farm variety had the highest number (22) of unique constitutive chemicals identified when compared with other varieties. This indicates the chemical distinctiveness of the Whitney Farm variety from the other varieties. In the varieties tested, there were common chemical compounds identified in constitutive and induced (discussed below) states of the plants such as caryophyllene, hexane, naphthalene, copaene and a-caryophyllene. Besides naphthalene, the majority of chemical compounds in South African L. camara varieties were similar to compounds that have been identified across the world, suggesting that they are closely related. The expression of naphthalene in these varieties may be due to changes in the chemicals expressed over evolutionary time as predicted by the Novel Weapons Hypothesis. Amongst the varieties, a great variation in chemical compounds and their concentrations was shown in the induced states of the plants. The concentration of constitutive caryophyllene ranged from (3.13 - 15.7) %, to (4.02 - 11.10) % after feeding. The concentration of constitutive hexane ranged from (6.13 - 71.19) %, to (33.3 - 75.8) % after feeding. The concentration of constitutive naphthalene ranged from (0.21 - 4.79) %, to (0.92 - 2.11) % after feeding. The concentration of constitutive copaene ranged from (0.57 - 1.57) %, to (1.20 - 2.72) %. Lastly, the concentration of constitutive a-caryophyllene ranged from (1.18 - 9.03) %, to (0.78 - 5.48) % after feeding. The changes in chemical concentrations in lantana varieties indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. To determine the effect of the identified compounds on the behaviour of F. intermedia adults, olfactometer bioassays were conducted using a Y-tube technique. A significantly higher proportion of F. intermedia were attracted to undamaged leaves over damaged leaves and purified air. Undamaged leaves attracted 52 % of F. intermedia from the East London variety, 62.5 % from the Port Alfred variety, 56 % from the Whitney Farm variety, 58 % from the Lyndhurst variety and 54.5 % from the Heather Glen variety in dual choice trials versus damaged leaves. Furthermore, a significantly higher proportion of F. intermedia were attracted to damaged leaves over purified air. Damaged leaves attracted 67 % of F. intermedia from the East London variety, 67 % from the Port Alfred variety, 65.9 % from the Whitney Farm variety, 65.3 % from the Heather Glen variety and 64.5 % from the Lyndhurst variety. Olfactometer bioassays were also conducted using purified standard compounds of four chemical compounds identified from essential oils, hexane was used as a positive control as it is reported to be an insect attractant in literature. Hexane was highly attractive to the mirids compared to three standard compounds caryophyllene, caryophyllene oxide and naphthalene at the rate of 80 %, 73 % and 80 %, respectively. The standard compounds tested against F. intermedia are major compounds contained by L. camara varieties and they have proven to have a repellent effect. This may indicate that after feeding by F. intermedia, the major compounds expressed by the plant varieties repel F. intermedia contributing to the invasiveness of this weed. The increased expression of hexane and caryophyllene after feeding may also indicate increased attraction to some insects, opening up the potential for third trophic level interactions in varieties where this is the case. This is the first study on the chemical composition of essential oils of L. camara in South Africa. Therefore, we recommend that where appropriate chemical profile studies of the invasive alien plants should be considered during host specificity testing, and the vital role of chemical compounds on agent-weed interactions must be taken into consideration with other factors before and after the biological control agents are released.
- Full Text:
- Authors: Ngxande-Koza, Samella W
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4877 , vital:20739
- Description: Lantana camara L. (Verbenaceae) is one the most problematic invaders in South Africa invading forest edges, sand dunes, and shorelines by forming impenetrable thickets. Lantana camara invasions degrade natural biodiversity, reduce the value of land and consequently it has been a target for biological control, over the last 50 years in South Africa. Studies that have reported on chemical profile of Lantana camara have been conducted around the world but not in South Africa. Hence, the first aim of the current study was to identify the chemical baseline of L. camara varieties in the Eastern Cape, South Africa. Recent studies have shown that feeding by one of the agents released against L. camara, Falconia intermedia (Distant) (Hemiptera: Miridae), induces anti-herbivory response through increased leaf toughness and trichome density. A preliminary study conducted also reported the production of volatile chemicals by one variety, Whitney Farm, due to feeding by the mirids. Therefore, the second aim was to determine the induced changes in chemical compounds of L. camara varieties after feeding by F. intermedia. A third aim was to determine the effect these chemical compounds have on the behaviour of F. intermedia. To identify the chemical baseline of L. camara varieties, the essential oils of four L. camara varieties (East London, Port Alfred, Whitney Farm and Heather Glen) were analysed using gas chromatography mass spectrometry (GC-MS) and that resulted to the identification of 163 constitutive and 75 induced chemicals across the varieties tested. Lantana camara varieties showed different chemical classes but were highly dominated by terpenes. A great variation in the number of constitutive chemical compounds was found in all the varieties. There were 56 constitutive chemical compounds in the Whitney Farm variety, 41 in the East London variety, 36 in the Heather Glen variety and 30 in the Port Alfred variety. The Whitney Farm variety had the highest number (22) of unique constitutive chemicals identified when compared with other varieties. This indicates the chemical distinctiveness of the Whitney Farm variety from the other varieties. In the varieties tested, there were common chemical compounds identified in constitutive and induced (discussed below) states of the plants such as caryophyllene, hexane, naphthalene, copaene and a-caryophyllene. Besides naphthalene, the majority of chemical compounds in South African L. camara varieties were similar to compounds that have been identified across the world, suggesting that they are closely related. The expression of naphthalene in these varieties may be due to changes in the chemicals expressed over evolutionary time as predicted by the Novel Weapons Hypothesis. Amongst the varieties, a great variation in chemical compounds and their concentrations was shown in the induced states of the plants. The concentration of constitutive caryophyllene ranged from (3.13 - 15.7) %, to (4.02 - 11.10) % after feeding. The concentration of constitutive hexane ranged from (6.13 - 71.19) %, to (33.3 - 75.8) % after feeding. The concentration of constitutive naphthalene ranged from (0.21 - 4.79) %, to (0.92 - 2.11) % after feeding. The concentration of constitutive copaene ranged from (0.57 - 1.57) %, to (1.20 - 2.72) %. Lastly, the concentration of constitutive a-caryophyllene ranged from (1.18 - 9.03) %, to (0.78 - 5.48) % after feeding. The changes in chemical concentrations in lantana varieties indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. To determine the effect of the identified compounds on the behaviour of F. intermedia adults, olfactometer bioassays were conducted using a Y-tube technique. A significantly higher proportion of F. intermedia were attracted to undamaged leaves over damaged leaves and purified air. Undamaged leaves attracted 52 % of F. intermedia from the East London variety, 62.5 % from the Port Alfred variety, 56 % from the Whitney Farm variety, 58 % from the Lyndhurst variety and 54.5 % from the Heather Glen variety in dual choice trials versus damaged leaves. Furthermore, a significantly higher proportion of F. intermedia were attracted to damaged leaves over purified air. Damaged leaves attracted 67 % of F. intermedia from the East London variety, 67 % from the Port Alfred variety, 65.9 % from the Whitney Farm variety, 65.3 % from the Heather Glen variety and 64.5 % from the Lyndhurst variety. Olfactometer bioassays were also conducted using purified standard compounds of four chemical compounds identified from essential oils, hexane was used as a positive control as it is reported to be an insect attractant in literature. Hexane was highly attractive to the mirids compared to three standard compounds caryophyllene, caryophyllene oxide and naphthalene at the rate of 80 %, 73 % and 80 %, respectively. The standard compounds tested against F. intermedia are major compounds contained by L. camara varieties and they have proven to have a repellent effect. This may indicate that after feeding by F. intermedia, the major compounds expressed by the plant varieties repel F. intermedia contributing to the invasiveness of this weed. The increased expression of hexane and caryophyllene after feeding may also indicate increased attraction to some insects, opening up the potential for third trophic level interactions in varieties where this is the case. This is the first study on the chemical composition of essential oils of L. camara in South Africa. Therefore, we recommend that where appropriate chemical profile studies of the invasive alien plants should be considered during host specificity testing, and the vital role of chemical compounds on agent-weed interactions must be taken into consideration with other factors before and after the biological control agents are released.
- Full Text:
Children and wild foods in the context of deforestation in rural Malawi
- Maseko, Heather N, Shackleton, Charlie M, Nagoli, J, Pullanikkatil, Deepa
- Authors: Maseko, Heather N , Shackleton, Charlie M , Nagoli, J , Pullanikkatil, Deepa
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182101 , vital:43800 , xlink:href="https://doi.org/10.1007/s10745-017-9956-8"
- Description: There is growing recognition of the contribution of wild foods to local diets, nutrition, and culture. Yet disaggregation of understanding of wild food use by gender and age is limited. We used a mixed methods approach to determine the types, frequencies, and perceptions of wild foods used and sold by children in four villages in southern Malawi that have different levels of deforestation. Household and individual dietary diversity scores are low at all sites. All households consume one or more wild foods. Across the four sites, children listed 119 wild foods, with a wider variety at the least deforested sites than the most deforested ones. Older children can name more wild foods than younger ones. More children from poor households sell wild foods than from well-off households. Several reasons were provided for the consumption or avoidance of wild foods (most commonly taste, contribution to health, limited alternatives, hunger, availability, local taboos).
- Full Text:
- Authors: Maseko, Heather N , Shackleton, Charlie M , Nagoli, J , Pullanikkatil, Deepa
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182101 , vital:43800 , xlink:href="https://doi.org/10.1007/s10745-017-9956-8"
- Description: There is growing recognition of the contribution of wild foods to local diets, nutrition, and culture. Yet disaggregation of understanding of wild food use by gender and age is limited. We used a mixed methods approach to determine the types, frequencies, and perceptions of wild foods used and sold by children in four villages in southern Malawi that have different levels of deforestation. Household and individual dietary diversity scores are low at all sites. All households consume one or more wild foods. Across the four sites, children listed 119 wild foods, with a wider variety at the least deforested sites than the most deforested ones. Older children can name more wild foods than younger ones. More children from poor households sell wild foods than from well-off households. Several reasons were provided for the consumption or avoidance of wild foods (most commonly taste, contribution to health, limited alternatives, hunger, availability, local taboos).
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Chinese aid and African agency since 2000: examining the cases of Zimbabwe, Angola and Ghana
- Authors: Chipaike, Ronald
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59151 , vital:27442
- Description: Restricted access-thesis embargoed for 2 years
- Full Text:
- Authors: Chipaike, Ronald
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59151 , vital:27442
- Description: Restricted access-thesis embargoed for 2 years
- Full Text:
Chinese Cabbage:
- Authors: Mwaba, Stary
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146699 , vital:38549 , https://www.ru.ac.za/artsofafrica/latestnews/rhodesparticipatesintheafrica-chinasymposiumatthegoetheinstitute.html
- Description: Stary Mwaba, an MFA candidate in the Arts of Africa and the Global South research team in the Fine Art Department, presented a paper on his installation, Chinese Cabbage, which was first displayed in his solo exhibition, Life on Mars, at the Künstlerhaus Bethanien in Germany in 2015. At the Africa–China symposium, Mwaba talked about his personal inroad into the Zambia–China debate, which draws from a family history of living along the Tazara Railway that was built by the Chinese in the 1960s, as well as the experience of his daughter attending a Chinese-run international school in Lusaka. Mwaba is currently expanding this research as part of his MFA studies at Rhodes by collecting oral narratives along the line of rail in Zambia and by addressing, through his painting practice, issues pertinent to the controversial copper slug known as Black Mountain in Kitwe.
- Full Text:
- Authors: Mwaba, Stary
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146699 , vital:38549 , https://www.ru.ac.za/artsofafrica/latestnews/rhodesparticipatesintheafrica-chinasymposiumatthegoetheinstitute.html
- Description: Stary Mwaba, an MFA candidate in the Arts of Africa and the Global South research team in the Fine Art Department, presented a paper on his installation, Chinese Cabbage, which was first displayed in his solo exhibition, Life on Mars, at the Künstlerhaus Bethanien in Germany in 2015. At the Africa–China symposium, Mwaba talked about his personal inroad into the Zambia–China debate, which draws from a family history of living along the Tazara Railway that was built by the Chinese in the 1960s, as well as the experience of his daughter attending a Chinese-run international school in Lusaka. Mwaba is currently expanding this research as part of his MFA studies at Rhodes by collecting oral narratives along the line of rail in Zambia and by addressing, through his painting practice, issues pertinent to the controversial copper slug known as Black Mountain in Kitwe.
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Closed doors: gendered power relations and the use of mature themes in Eurocentric fairytales
- Authors: Sawyer, Kathleen Patricia
- Date: 2017
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/5971 , vital:21003
- Description: Established critics, such as Jack Zipes, assert that the subject matter of fairytales shows evidence that the Westernised 'classics' (by authors such as Charles Perrault or the Grimm brothers) were influenced by the cultural norms of their contemporary society and served as a pedagogical tool for mass socialisation. Often authors writing for younger audiences deliberately inserted a moralising function into these tales, in order to normalise and further disseminate certain gender ideals. Their presentation of adult or mature themes (such as sexuality) is often problematic, with some references presented quite naturally and others excluded entirely. This paper investigates modern retellings of Eurocentric fairytales, and speculates on the significance of the perpetuation or complete elision of such themes, and what their selective invocation might intimate about the culture in which the story is produced. It argues that the way in which the fairytale narrative engages with mature themes is demonstrative of its contemporary ethos and its associated cultural bias, which is conveyed unconsciously through the vehicle of the text. Through a critical analysis of relevant literature, the paper explores the maintenance of socio-cultural norms in fairytales as being emblematic in their establishment as cultural relics.
- Full Text:
- Authors: Sawyer, Kathleen Patricia
- Date: 2017
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/5971 , vital:21003
- Description: Established critics, such as Jack Zipes, assert that the subject matter of fairytales shows evidence that the Westernised 'classics' (by authors such as Charles Perrault or the Grimm brothers) were influenced by the cultural norms of their contemporary society and served as a pedagogical tool for mass socialisation. Often authors writing for younger audiences deliberately inserted a moralising function into these tales, in order to normalise and further disseminate certain gender ideals. Their presentation of adult or mature themes (such as sexuality) is often problematic, with some references presented quite naturally and others excluded entirely. This paper investigates modern retellings of Eurocentric fairytales, and speculates on the significance of the perpetuation or complete elision of such themes, and what their selective invocation might intimate about the culture in which the story is produced. It argues that the way in which the fairytale narrative engages with mature themes is demonstrative of its contemporary ethos and its associated cultural bias, which is conveyed unconsciously through the vehicle of the text. Through a critical analysis of relevant literature, the paper explores the maintenance of socio-cultural norms in fairytales as being emblematic in their establishment as cultural relics.
- Full Text: