Graphene quantum dots functionalized with 4-amino-2, 2, 6, 6-tetramethylpiperidine-N-oxide as fluorescence “turn-on” nanosensors
- Achadu, Ojodomo J, Britton, Jonathan, Nyokong, Tebello
- Authors: Achadu, Ojodomo J , Britton, Jonathan , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239854 , vital:50773 , xlink:href="https://doi.org/10.1007/s10895-016-1916-y"
- Description: In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo J , Britton, Jonathan , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239854 , vital:50773 , xlink:href="https://doi.org/10.1007/s10895-016-1916-y"
- Description: In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.
- Full Text:
- Date Issued: 2016
Interaction of graphene quantum dots with 4-acetamido-2, 2, 6, 6-tetramethylpiperidine-oxyl free radicals
- Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
The interaction between graphene quantum dots grafted with polyethyleneimine and Au@ Ag nanoparticles
- Achadu, Ojodomo John, Uddin, Imran, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188679 , vital:44775 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.03.016"
- Description: Graphene quantum dots grafted with polyethyleneimine (GQDs-PEI) and Au@Ag core-shell nanoparticles blend was demonstrated to be a novel biosensing nanoprobe for the rapid and highly sensitive detection of biothiols such as cysteine (Cys), homocysteine (Hcys) and glutathione (GSH). The fluorescence emission of GQDs-PEI was quenched efficiently upon interaction with Au@Ag core-shell nanoparticles. The quenched fluorescence emission of the GQDs-PEI was restored in the presence of the biothiols. The fluorimetric sensing is based on the strong affinity between the mercapto (SH) groups of the biothiols and the Au@Ag core-shell nanoparticles by which the interaction between GQDs-PEI and Au@Ag core-shell nanoparticles was disrupted with a consequent modulation (‘turn-on’) of the quenched GQDs-PEI emission. Thus, a new, simple, rapid and highly sensitive fluorescence nanoprobe for detecting biothiols has been developed in this work.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188679 , vital:44775 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.03.016"
- Description: Graphene quantum dots grafted with polyethyleneimine (GQDs-PEI) and Au@Ag core-shell nanoparticles blend was demonstrated to be a novel biosensing nanoprobe for the rapid and highly sensitive detection of biothiols such as cysteine (Cys), homocysteine (Hcys) and glutathione (GSH). The fluorescence emission of GQDs-PEI was quenched efficiently upon interaction with Au@Ag core-shell nanoparticles. The quenched fluorescence emission of the GQDs-PEI was restored in the presence of the biothiols. The fluorimetric sensing is based on the strong affinity between the mercapto (SH) groups of the biothiols and the Au@Ag core-shell nanoparticles by which the interaction between GQDs-PEI and Au@Ag core-shell nanoparticles was disrupted with a consequent modulation (‘turn-on’) of the quenched GQDs-PEI emission. Thus, a new, simple, rapid and highly sensitive fluorescence nanoprobe for detecting biothiols has been developed in this work.
- Full Text:
- Date Issued: 2016
Fluorescence behavior of nanoconjugates of graphene quantum dots and zinc phthalocyanines
- Achadu, Ojodomo John, Uddin, Imran, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
Distribution and use of cash income from basket and mat crafting: Implications for rural livelihoods in the Eastern Cape, South Africa
- Adam, Y O, Shackleton, Charlie M
- Authors: Adam, Y O , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180434 , vital:43388 , xlink:href="https://doi.org/10.1080/14728028.2016.1186576"
- Description: The objective of this paper was to investigate the extent to which baskets and mats local trade contributes to rural livelihoods of the crafters’ household and community downstream income. Primary data were collected through structured interviews with 83 crafters from Noqhekwana village in Port St. Johns municipality using snowball sampling in May, 2015. The survey was supplemented by secondary data and direct observations. The findings show that crafting contributed 35% of crafter’s household total income. The received income is spent on expenses in the household and downstream actors depending on the crafter’s priorities. Lack of organization between crafters, access to sufficient raw material, and low prices were identified as major challenges involved in the production and trade of the products.
- Full Text:
- Date Issued: 2016
- Authors: Adam, Y O , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180434 , vital:43388 , xlink:href="https://doi.org/10.1080/14728028.2016.1186576"
- Description: The objective of this paper was to investigate the extent to which baskets and mats local trade contributes to rural livelihoods of the crafters’ household and community downstream income. Primary data were collected through structured interviews with 83 crafters from Noqhekwana village in Port St. Johns municipality using snowball sampling in May, 2015. The survey was supplemented by secondary data and direct observations. The findings show that crafting contributed 35% of crafter’s household total income. The received income is spent on expenses in the household and downstream actors depending on the crafter’s priorities. Lack of organization between crafters, access to sufficient raw material, and low prices were identified as major challenges involved in the production and trade of the products.
- Full Text:
- Date Issued: 2016
Fluorescence properties of alloyed ZnSeS quantum dots overcoated with ZnTe and ZnTe/ZnS shells
- Adegoke, Oluwasesan, Mashazi, Philani N, Nyokong, Tebello, Forbes, Patricia B C
- Authors: Adegoke, Oluwasesan , Mashazi, Philani N , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240754 , vital:50868 , xlink:href="https://doi.org/10.1016/j.optmat.2016.02.024"
- Description: Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.
- Full Text:
- Date Issued: 2016
- Authors: Adegoke, Oluwasesan , Mashazi, Philani N , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240754 , vital:50868 , xlink:href="https://doi.org/10.1016/j.optmat.2016.02.024"
- Description: Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.
- Full Text:
- Date Issued: 2016
SEAmester – South Africa’s first class afloat
- Ansorge, Isabelle J, Brundrit, Geoff, Brundrit, Jean, Dorrington, Rosemary A, Fawcett, Sarah, Gammon, David, Henry, Tahlia, Hermes, Juliet, Hölscher, Beate, d’Hotman, Jethan, Meiklejohn, Ian, Morris, Tammy, Pinto, Izidine, Du Plessis, Marcel, Roman, Raymond, Saunders, Clinton, Shabangu, Fannie W, De Vos, Marc, Walker, David R, Louw, Gavin
- Authors: Ansorge, Isabelle J , Brundrit, Geoff , Brundrit, Jean , Dorrington, Rosemary A , Fawcett, Sarah , Gammon, David , Henry, Tahlia , Hermes, Juliet , Hölscher, Beate , d’Hotman, Jethan , Meiklejohn, Ian , Morris, Tammy , Pinto, Izidine , Du Plessis, Marcel , Roman, Raymond , Saunders, Clinton , Shabangu, Fannie W , De Vos, Marc , Walker, David R , Louw, Gavin
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/65539 , vital:28808 , https://doi.org/10.17159/sajs.2016/a0171
- Description: publisher version , From Introduction: Marine science is a highly competitive environment. The need to improve the cohort of South African postgraduates, who would be recognised both nationally and internationally for their scientific excellence, is crucial. It is possible to attract students early on in their careers to this discipline via cutting-edge science, technology and unique field experiences. Through the engagement of students with real-life experiences such as SEAmester, universities supporting marine science postgraduate degree programmes can attract a sustainable throughput of numerically proficient students. By achieving a more quantitative and experienced input into our postgraduate degree programmes, we will, as a scientific community, greatly improve our long-term capabilities to accurately measure, model and predict the impacts of current climate change scenarios. The short-term goal is to attract and establish a cohort of proficient marine and atmospheric science graduates who will contribute to filling the capacity needs of South African marine science as a whole. The SEAmester programme, by involving researchers from across all the relevant disciplines and tertiary institutions, provides an opportunity to build a network of collaborative teaching within the marine field. In doing so, these researchers will foster and strengthen new and current collaborations between historically white and black universities (Figure 1). The long-term objective of SEAmester is to build critical mass within the marine sciences to ensure sustained growth of human capacity in marine science in South Africa – aligning closely with the current DST Research and Development strategies and the Operation Phakisa Oceans Economy initiative.
- Full Text:
- Date Issued: 2016
- Authors: Ansorge, Isabelle J , Brundrit, Geoff , Brundrit, Jean , Dorrington, Rosemary A , Fawcett, Sarah , Gammon, David , Henry, Tahlia , Hermes, Juliet , Hölscher, Beate , d’Hotman, Jethan , Meiklejohn, Ian , Morris, Tammy , Pinto, Izidine , Du Plessis, Marcel , Roman, Raymond , Saunders, Clinton , Shabangu, Fannie W , De Vos, Marc , Walker, David R , Louw, Gavin
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/65539 , vital:28808 , https://doi.org/10.17159/sajs.2016/a0171
- Description: publisher version , From Introduction: Marine science is a highly competitive environment. The need to improve the cohort of South African postgraduates, who would be recognised both nationally and internationally for their scientific excellence, is crucial. It is possible to attract students early on in their careers to this discipline via cutting-edge science, technology and unique field experiences. Through the engagement of students with real-life experiences such as SEAmester, universities supporting marine science postgraduate degree programmes can attract a sustainable throughput of numerically proficient students. By achieving a more quantitative and experienced input into our postgraduate degree programmes, we will, as a scientific community, greatly improve our long-term capabilities to accurately measure, model and predict the impacts of current climate change scenarios. The short-term goal is to attract and establish a cohort of proficient marine and atmospheric science graduates who will contribute to filling the capacity needs of South African marine science as a whole. The SEAmester programme, by involving researchers from across all the relevant disciplines and tertiary institutions, provides an opportunity to build a network of collaborative teaching within the marine field. In doing so, these researchers will foster and strengthen new and current collaborations between historically white and black universities (Figure 1). The long-term objective of SEAmester is to build critical mass within the marine sciences to ensure sustained growth of human capacity in marine science in South Africa – aligning closely with the current DST Research and Development strategies and the Operation Phakisa Oceans Economy initiative.
- Full Text:
- Date Issued: 2016
Recommendations for the future of recreational fisheries to prepare the social‐ecological system to cope with change
- Arlinghaus, Robert, Cooke, Steven J, Sutton, S G, Danylchuk, A J, Potts, Warren M, Freire, K D M, Alós, J, Da Silva, E T, Cowx, Ian G, Van Anrooy, R
- Authors: Arlinghaus, Robert , Cooke, Steven J , Sutton, S G , Danylchuk, A J , Potts, Warren M , Freire, K D M , Alós, J , Da Silva, E T , Cowx, Ian G , Van Anrooy, R
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125810 , vital:35819 , https://doi.10.1111/fme.12191
- Description: This paper presents conclusions and recommendations that emerged from the 7th World Recreational Fishing Conference (WRFC) held in Campinas, Brazil in September 2014. Based on the recognition of the immense social and economic importance of recreational fisheries coupled with weaknesses in robust information about these fisheries in many areas of the world, particularly in many economies in transition, it is recommended to increase effort to build effective governance arrangements and improve monitoring and assessment frameworks in data-poor situations. Moreover, there is a need to increase interdisciplinary studies that will foster a systematic understanding of recreational fisheries as complex adaptive social-ecological systems. To promote sustainable recreational fisheries on a global scale, it is recommended the detailed suggestions for governance and management outlined in the United Nations Food and Agricultural Organization Technical Guidelines for Responsible Fisheries: Recreational Fisheries are followed.
- Full Text:
- Date Issued: 2016
- Authors: Arlinghaus, Robert , Cooke, Steven J , Sutton, S G , Danylchuk, A J , Potts, Warren M , Freire, K D M , Alós, J , Da Silva, E T , Cowx, Ian G , Van Anrooy, R
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125810 , vital:35819 , https://doi.10.1111/fme.12191
- Description: This paper presents conclusions and recommendations that emerged from the 7th World Recreational Fishing Conference (WRFC) held in Campinas, Brazil in September 2014. Based on the recognition of the immense social and economic importance of recreational fisheries coupled with weaknesses in robust information about these fisheries in many areas of the world, particularly in many economies in transition, it is recommended to increase effort to build effective governance arrangements and improve monitoring and assessment frameworks in data-poor situations. Moreover, there is a need to increase interdisciplinary studies that will foster a systematic understanding of recreational fisheries as complex adaptive social-ecological systems. To promote sustainable recreational fisheries on a global scale, it is recommended the detailed suggestions for governance and management outlined in the United Nations Food and Agricultural Organization Technical Guidelines for Responsible Fisheries: Recreational Fisheries are followed.
- Full Text:
- Date Issued: 2016
Geospatial technologies and indigenous Knowledge Systems:
- Authors: Aswani, Shankar
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/145448 , vital:38439 , ISBN 9781315181523 , https://www.taylorfrancis.com/books/e/9781315181523/chapters/10.1201/9781315181523-18
- Description: During the twentieth and twenty-first centuries, pressure on coastal ecosystems has amplified and resulted in the widespread degradation of adjacent marine and terrestrial habitats globally (Burke et al., 2001). The ecosystem services provided by coastal habitats, including coastal protection and food procurement, have been heavily compromised by anthropogenic disturbance such as overfishing, pollution, sedimentation and alteration of coastal vegetation (Costanza et al., 1997; Agardy et al., 2009). In the context of small islands, this continued degradation in tandem with the ongoing effects of climate change is putting the livelihoods of coastal peoples at risk (e.g. Bell et al., 2009). While international efforts at curtailing these negative trends are ongoing, many researchers are working directly with coastal local/ indigenous communities to seek more effective management of coastal terrestrial and marine resources. Among various approaches, researchers are increasingly incorporating local knowledge systems for designing resource management and conservation plans (e.g. Gadgil et al., 1993).
- Full Text:
- Date Issued: 2016
- Authors: Aswani, Shankar
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/145448 , vital:38439 , ISBN 9781315181523 , https://www.taylorfrancis.com/books/e/9781315181523/chapters/10.1201/9781315181523-18
- Description: During the twentieth and twenty-first centuries, pressure on coastal ecosystems has amplified and resulted in the widespread degradation of adjacent marine and terrestrial habitats globally (Burke et al., 2001). The ecosystem services provided by coastal habitats, including coastal protection and food procurement, have been heavily compromised by anthropogenic disturbance such as overfishing, pollution, sedimentation and alteration of coastal vegetation (Costanza et al., 1997; Agardy et al., 2009). In the context of small islands, this continued degradation in tandem with the ongoing effects of climate change is putting the livelihoods of coastal peoples at risk (e.g. Bell et al., 2009). While international efforts at curtailing these negative trends are ongoing, many researchers are working directly with coastal local/ indigenous communities to seek more effective management of coastal terrestrial and marine resources. Among various approaches, researchers are increasingly incorporating local knowledge systems for designing resource management and conservation plans (e.g. Gadgil et al., 1993).
- Full Text:
- Date Issued: 2016
A Review of Arterial Stiffness and HIV Infection in Adult Africans
- Awotedu, Kofoworola Olajire, Iputo, Jehu
- Authors: Awotedu, Kofoworola Olajire , Iputo, Jehu
- Date: 09-06-2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3484 , vital:43615 , https://www.hilarispublisher.com/open-access/a-review-of-arterial-stiffness-and-hiv-infection-in-adult-africans-2167-1095-1000221.pdf
- Description: Aim: To review the impact of the human immunodeficiency virus and antiretroviral therapy on the vasculature. Objectives: This review seeks to identify the burden which the human immunodeficiency virus and antiretroviral therapy have on the vasculature. Method: Medline/PubMed and Google scholar were searched. There were over 100 publications reviewed. Some people who worked in similar fields were also contacted. The present review summarized current understanding of Human immunodeficiency virus, antiretroviral therapy and effect on the vasculature such as arterial stiffness. Atherosclerosis, endothelial dysfunction, the strengths and weaknesses of current testing strategies, and their potential applications in clinical research and patient care. The association of inflammatory biomarkers, blood pressure and ageing with arterial stiffness were also reviewed. Conclusion: Available literature shows that HIV and antiretroviral agents have a great impact on the vasculature and its progression.
- Full Text:
- Date Issued: 09-06-2016
- Authors: Awotedu, Kofoworola Olajire , Iputo, Jehu
- Date: 09-06-2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3484 , vital:43615 , https://www.hilarispublisher.com/open-access/a-review-of-arterial-stiffness-and-hiv-infection-in-adult-africans-2167-1095-1000221.pdf
- Description: Aim: To review the impact of the human immunodeficiency virus and antiretroviral therapy on the vasculature. Objectives: This review seeks to identify the burden which the human immunodeficiency virus and antiretroviral therapy have on the vasculature. Method: Medline/PubMed and Google scholar were searched. There were over 100 publications reviewed. Some people who worked in similar fields were also contacted. The present review summarized current understanding of Human immunodeficiency virus, antiretroviral therapy and effect on the vasculature such as arterial stiffness. Atherosclerosis, endothelial dysfunction, the strengths and weaknesses of current testing strategies, and their potential applications in clinical research and patient care. The association of inflammatory biomarkers, blood pressure and ageing with arterial stiffness were also reviewed. Conclusion: Available literature shows that HIV and antiretroviral agents have a great impact on the vasculature and its progression.
- Full Text:
- Date Issued: 09-06-2016
Nonlinear optical response of a low symmetry phthalocyanine in the presence of gold nanoparticles when in solution or embedded in poly acrylic acid polymer thin films
- Bankole, Owolabi M, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188719 , vital:44779 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.12.014"
- Description: In this article, we explored the photophysical and nonlinear optical (NLO) characterizations of low symmetry phthalocyanine (ZnPc-NH2) covalently linked to MPA-capped AuNPs (ZnPc-NH2-AuNPs) and poly acrylic acid (ZnPc-NH2-PAA). Nonlinear optical (NLO) properties of the samples were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. We observed enhanced photophysical and nonlinear optical behaviour for the ZnPc-NH2 in presence of AuNPs. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, ZnPc-NH2-AuNPs was found to exhibit improved nonlinear optical response compared to the ZnPc-NH2 and ZnPc-NH2-PAA. Both ZnPc-NH2-AuNPs and ZnPc-NH2 doped in PAA possess strong nonlinear absorption coefficients and very low limiting thresholds than when measured in solution.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188719 , vital:44779 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.12.014"
- Description: In this article, we explored the photophysical and nonlinear optical (NLO) characterizations of low symmetry phthalocyanine (ZnPc-NH2) covalently linked to MPA-capped AuNPs (ZnPc-NH2-AuNPs) and poly acrylic acid (ZnPc-NH2-PAA). Nonlinear optical (NLO) properties of the samples were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. We observed enhanced photophysical and nonlinear optical behaviour for the ZnPc-NH2 in presence of AuNPs. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, ZnPc-NH2-AuNPs was found to exhibit improved nonlinear optical response compared to the ZnPc-NH2 and ZnPc-NH2-PAA. Both ZnPc-NH2-AuNPs and ZnPc-NH2 doped in PAA possess strong nonlinear absorption coefficients and very low limiting thresholds than when measured in solution.
- Full Text:
- Date Issued: 2016
Comparative studies on photophysical and optical limiting characterizations of low symmetry phthalocyanine linked to Fe 3 O 4–Ag core–shell or hybrid nanoparticles
- Bankole, Owolabi M, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188788 , vital:44785 , xlink:href="https://doi.org/10.1039/C6NJ01511E"
- Description: Photophysical and nonlinear optical (NLO) behaviours of low symmetry zinc phthalocyanine (1) linked to Fe3O4/Ag core–shell (represented as Fe/Ag) or Fe3O4–Ag hybrid (represented as FeAg) nanoparticles were investigated in DMSO. Triplet quantum yields and NLO parameters of phthalocyanine improved due to the combined effects of magnetic–metallic nanoparticles. A direct relationship between the increased triplet excited state absorptions by already excited molecules and reverse saturable absorption (RSA) was established as the predominant mechanism responsible for nonlinearity of the samples. Our findings show that, at the same approximate concentrations and conditions, 1-FeAg enhanced the OL potentials of 1 more than 1-Fe/Ag.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188788 , vital:44785 , xlink:href="https://doi.org/10.1039/C6NJ01511E"
- Description: Photophysical and nonlinear optical (NLO) behaviours of low symmetry zinc phthalocyanine (1) linked to Fe3O4/Ag core–shell (represented as Fe/Ag) or Fe3O4–Ag hybrid (represented as FeAg) nanoparticles were investigated in DMSO. Triplet quantum yields and NLO parameters of phthalocyanine improved due to the combined effects of magnetic–metallic nanoparticles. A direct relationship between the increased triplet excited state absorptions by already excited molecules and reverse saturable absorption (RSA) was established as the predominant mechanism responsible for nonlinearity of the samples. Our findings show that, at the same approximate concentrations and conditions, 1-FeAg enhanced the OL potentials of 1 more than 1-Fe/Ag.
- Full Text:
- Date Issued: 2016
Nonlinear optical behavior of alkyne terminated phthalocyanines in solution and when embedded in polysulfone as thin films: effects of aggregation
- Bankole, Owolabi M, Yilmaz, Yusuf, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Yilmaz, Yusuf , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189110 , vital:44817 , xlink:href="https://doi.org/10.1016/j.optmat.2015.11.041"
- Description: We report here for the first time, on the comparative studies of the photophysical and optical limiting behavior of our two novel phthalocyanines namely 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyanines 2, and 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyaninato zinc (II) (3) in solution and thin films. Nonlinear optical (NLO) properties of the samples in solution and contained in polysulfone (PSU) thin films were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. Effects of aggregation and disaggregation on the NLO performance of metal-free phthalocyanine are reported in detail. Our findings showed that the prepared Pcs show larger nonlinear absorption coefficient and lower limiting thresholds when embedded in polysulfone films compared to in solutions. The values of nonlinear susceptibility and hyperpolarizability recorded for 3-PSU in this work are respectively, ∼2.09 × 10−8 esu and ∼1.02 × 10−26 esu. These values are among the largest values reported for phthalocyanines and other macrocycles doped on polymer matrices.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Yilmaz, Yusuf , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189110 , vital:44817 , xlink:href="https://doi.org/10.1016/j.optmat.2015.11.041"
- Description: We report here for the first time, on the comparative studies of the photophysical and optical limiting behavior of our two novel phthalocyanines namely 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyanines 2, and 2(3), 9(10), 16(17), 23(24)-tetrakis-(4-(5-methylhex-1-yn-3-yloxy)) phthalocyaninato zinc (II) (3) in solution and thin films. Nonlinear optical (NLO) properties of the samples in solution and contained in polysulfone (PSU) thin films were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. Effects of aggregation and disaggregation on the NLO performance of metal-free phthalocyanine are reported in detail. Our findings showed that the prepared Pcs show larger nonlinear absorption coefficient and lower limiting thresholds when embedded in polysulfone films compared to in solutions. The values of nonlinear susceptibility and hyperpolarizability recorded for 3-PSU in this work are respectively, ∼2.09 × 10−8 esu and ∼1.02 × 10−26 esu. These values are among the largest values reported for phthalocyanines and other macrocycles doped on polymer matrices.
- Full Text:
- Date Issued: 2016
Enhanced nonlinear optical responses of zinc diaminopyrimidin-2-ylthio phthalocyanine conjugated to AgxAuy alloy nanoparticles
- Bankole, Owolabi M, Osifeko, Olawale, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240382 , vital:50829 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.06.025"
- Description: In this article, the photophysical and nonlinear optical (NLO) characterizations of diaminopyrimidin-2-ylthio phthalocyaninatozinc (II) (2) before and after conjugation to AgxAuy nano-alloys are discussed. Phthalocyanines-AgxAuy (2-AgxAuy) composites showed enhanced triplet state and nonlinear optical behaviour when compared to free phthalocyanine. Optical limiting (OL) responses of the samples were evaluated using Z-scan technique at 532 nm and 10 ns in dimethyl sulfoxide. Reverse saturable absorption (RSA), which is a direct consequence of triplet absorption of already excited molecules was observed as the dominant mechanism responsible for nonlinearity of the samples. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, 2-AgxAuy composites were found to exhibit stronger optical limiting responses than unconjugated phthalocyanine. The large third-order susceptibilities of the composites make them suitable materials for attenuating modern laser radiations, and also found useful in various optical applications.
- Full Text:
- Date Issued: 2016
- Authors: Bankole, Owolabi M , Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240382 , vital:50829 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.06.025"
- Description: In this article, the photophysical and nonlinear optical (NLO) characterizations of diaminopyrimidin-2-ylthio phthalocyaninatozinc (II) (2) before and after conjugation to AgxAuy nano-alloys are discussed. Phthalocyanines-AgxAuy (2-AgxAuy) composites showed enhanced triplet state and nonlinear optical behaviour when compared to free phthalocyanine. Optical limiting (OL) responses of the samples were evaluated using Z-scan technique at 532 nm and 10 ns in dimethyl sulfoxide. Reverse saturable absorption (RSA), which is a direct consequence of triplet absorption of already excited molecules was observed as the dominant mechanism responsible for nonlinearity of the samples. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, 2-AgxAuy composites were found to exhibit stronger optical limiting responses than unconjugated phthalocyanine. The large third-order susceptibilities of the composites make them suitable materials for attenuating modern laser radiations, and also found useful in various optical applications.
- Full Text:
- Date Issued: 2016
Parallel visions: Byron, Géricault and the Medusa
- Authors: Beard, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147792 , vital:38673 , https://doi.org/10.1080/00043389.1999.11761285
- Description: Martin Meisel has noted that Delacroix's 1841 painting A Shipwreck was recognised as uniting Gericault and Byron. for not only does the painting illustrate that moment in Don Juan when lots are drawn for the human sacrifice {2, 75) but it also invokes comparison with Gericault' s 1819 painting entitled Raft of the Medusa(Meisel1988:601).1 would like to argue in this paper that Gericault' s famous painting and Byron's shipwreck stanzas in the second canto of Don Juan have other points of comparison. Gericault used the Savigny and Correard Narrative of a Voyage to Senegal ( 1817) as the primary source of information for his treatment of the Medusa incident (Eitner 1971: 117). Byron used multiple sources when he researched material for his shipwreck stanzas but it is highly probable that the Savigny and Correard text was one of them. Thus, the cause celebre of the wreck of the Medusa is directly treated by Gericault and indirectly by Byron - two artists temperamentally and artistically attuned.
- Full Text:
- Date Issued: 2016
- Authors: Beard, Margot
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147792 , vital:38673 , https://doi.org/10.1080/00043389.1999.11761285
- Description: Martin Meisel has noted that Delacroix's 1841 painting A Shipwreck was recognised as uniting Gericault and Byron. for not only does the painting illustrate that moment in Don Juan when lots are drawn for the human sacrifice {2, 75) but it also invokes comparison with Gericault' s 1819 painting entitled Raft of the Medusa(Meisel1988:601).1 would like to argue in this paper that Gericault' s famous painting and Byron's shipwreck stanzas in the second canto of Don Juan have other points of comparison. Gericault used the Savigny and Correard Narrative of a Voyage to Senegal ( 1817) as the primary source of information for his treatment of the Medusa incident (Eitner 1971: 117). Byron used multiple sources when he researched material for his shipwreck stanzas but it is highly probable that the Savigny and Correard text was one of them. Thus, the cause celebre of the wreck of the Medusa is directly treated by Gericault and indirectly by Byron - two artists temperamentally and artistically attuned.
- Full Text:
- Date Issued: 2016
Counting on demographic equity to transform institutional cultures at historically white South African universities?:
- Booi, Masixole, Vincent, Louise, Liccardo, Sabrina
- Authors: Booi, Masixole , Vincent, Louise , Liccardo, Sabrina
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141946 , vital:38018 , DOI: 10.1080/07294360.2017.1289155
- Description: The post-apartheid higher education transformation project is faced with the challenge of recruiting and retaining black academics and other senior staff. But when we shift the focus from participation rates to equality–inequality within historically white universities (HWUs), then the discourse changes from demographic equity and redress to institutional culture and diversity. HWUs invoke the need to maintain their position as leading higher education institutions globally, and notions of ‘quality’ and ‘excellence’ have emerged as discursive practices, which serve to perpetuate exclusion. The question then arises as to which forms of capital comprise the Gold Standard at HWUs? Several South African universities have responded to the challenge of recruiting and retaining black academics by initiating programmes for the ‘accelerated development’ of these candidates.
- Full Text:
- Date Issued: 2017
- Authors: Booi, Masixole , Vincent, Louise , Liccardo, Sabrina
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141946 , vital:38018 , DOI: 10.1080/07294360.2017.1289155
- Description: The post-apartheid higher education transformation project is faced with the challenge of recruiting and retaining black academics and other senior staff. But when we shift the focus from participation rates to equality–inequality within historically white universities (HWUs), then the discourse changes from demographic equity and redress to institutional culture and diversity. HWUs invoke the need to maintain their position as leading higher education institutions globally, and notions of ‘quality’ and ‘excellence’ have emerged as discursive practices, which serve to perpetuate exclusion. The question then arises as to which forms of capital comprise the Gold Standard at HWUs? Several South African universities have responded to the challenge of recruiting and retaining black academics by initiating programmes for the ‘accelerated development’ of these candidates.
- Full Text:
- Date Issued: 2017
Lives "on hold": the Daily Sun and the South African identity document
- Authors: Boshoff, Priscilla A
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143538 , vital:38255 , https://hdl.handle.net/10520/EJC195358
- Description: The relationship between a personal identity and the state-issued Identity Document (ID) is the focus of this article, which examines stories published in the "Horror Affairs" column of the popular South African tabloid, the Daily Sun. These highly emotional stories tell of the despair and desperation felt by individuals at the lack of an ID book, which is blamed on the inefficiency of the state Department of Home Affairs. In order to explicate this relationship I make use of Agamben's notion of "bare life" and the camp in conjunction with Lacan's idea of the Symbolic Order to argue that if the Identity Document provides the means by which the individual is made to signify, the lack of an Identity Document threatens to reduce the individual to "bare life". By publishing the stories of those deprived of the visibility that the ID provides, the Daily Sun, I show, directly engages in this exchange, and, in contrast to Home Affairs, bestows its own even stronger gift of identity by the fact of appearance in its pages.
- Full Text:
- Date Issued: 2016
- Authors: Boshoff, Priscilla A
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143538 , vital:38255 , https://hdl.handle.net/10520/EJC195358
- Description: The relationship between a personal identity and the state-issued Identity Document (ID) is the focus of this article, which examines stories published in the "Horror Affairs" column of the popular South African tabloid, the Daily Sun. These highly emotional stories tell of the despair and desperation felt by individuals at the lack of an ID book, which is blamed on the inefficiency of the state Department of Home Affairs. In order to explicate this relationship I make use of Agamben's notion of "bare life" and the camp in conjunction with Lacan's idea of the Symbolic Order to argue that if the Identity Document provides the means by which the individual is made to signify, the lack of an Identity Document threatens to reduce the individual to "bare life". By publishing the stories of those deprived of the visibility that the ID provides, the Daily Sun, I show, directly engages in this exchange, and, in contrast to Home Affairs, bestows its own even stronger gift of identity by the fact of appearance in its pages.
- Full Text:
- Date Issued: 2016
Russian wheat aphids: Breakfast, lunch, and supper. Feasting on small grains in South Africa
- Botha, Christiaan E J, Sacranie, S, Gallagher, Sean, Hill, Jaclyn M
- Authors: Botha, Christiaan E J , Sacranie, S , Gallagher, Sean , Hill, Jaclyn M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69031 , vital:29374 , https://doi.org/10.1016/j.sajb.2016.12.006
- Description: The Russian Wheat Aphid (Diuraphis noxia, RWA) negatively impacts commercially grown barley and wheat in South Africa. Climate change, the attendant rise in [CO2], and the appearance of new RWA biotypes have the potential to induce severe crop yield loss in agriculturally important wheat and barley cultivars. This study presents data showing changes in relative aphid population numbers, concurrently with assessments of plant damage under controlled environmental conditions, under ambient and elevated (450 ppm) [CO2]. Extensive structural damage to the vascular tissue and disruption to the transport systems were revealed using light, fluorescence and electron microscopy. This, coupled with biotype population studies, demonstrated that RWA has the capacity to inflict severe, potentially permanent damage to vegetative small grain plants. Furthermore, some currently ‘resistant’ cultivars may well lose resistance as a direct result of increasing atmospheric [CO2]. A small (50 ppm) increase in atmospheric [CO2] may result in increased aphid population numbers, potentially serious plant damage and, by implication, a potentially negative impact on yield, as increased aphid density per plant leads to an accelerated disruption of the assimilate and transpiration transport pathways. These outcomes pose a direct threat to the commercial small grain industry of South Africa and by extension, to other small grain production areas elsewhere.
- Full Text: false
- Date Issued: 2016
- Authors: Botha, Christiaan E J , Sacranie, S , Gallagher, Sean , Hill, Jaclyn M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69031 , vital:29374 , https://doi.org/10.1016/j.sajb.2016.12.006
- Description: The Russian Wheat Aphid (Diuraphis noxia, RWA) negatively impacts commercially grown barley and wheat in South Africa. Climate change, the attendant rise in [CO2], and the appearance of new RWA biotypes have the potential to induce severe crop yield loss in agriculturally important wheat and barley cultivars. This study presents data showing changes in relative aphid population numbers, concurrently with assessments of plant damage under controlled environmental conditions, under ambient and elevated (450 ppm) [CO2]. Extensive structural damage to the vascular tissue and disruption to the transport systems were revealed using light, fluorescence and electron microscopy. This, coupled with biotype population studies, demonstrated that RWA has the capacity to inflict severe, potentially permanent damage to vegetative small grain plants. Furthermore, some currently ‘resistant’ cultivars may well lose resistance as a direct result of increasing atmospheric [CO2]. A small (50 ppm) increase in atmospheric [CO2] may result in increased aphid population numbers, potentially serious plant damage and, by implication, a potentially negative impact on yield, as increased aphid density per plant leads to an accelerated disruption of the assimilate and transpiration transport pathways. These outcomes pose a direct threat to the commercial small grain industry of South Africa and by extension, to other small grain production areas elsewhere.
- Full Text: false
- Date Issued: 2016
Art investment in South Africa: portfolio diversification and art market efficiency
- Botha, Ferdi, Snowball, Jeanette D, Scott, Brett
- Authors: Botha, Ferdi , Snowball, Jeanette D , Scott, Brett
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64794 , vital:28601 , http://www.dx.doi.org/10.17159/2222-3436/2016/v19n3a4
- Description: Art has been suggested as a good way to diversify investment portfolios during times of financial uncertainty. The argument is that art exhibits different risk and return characteristics to conventional investments in other asset classes. The new Citadel art price index offered the opportunity to test this theory in the South African context. Moreover, this paper tests whether art prices are efficient. The Citadel index uses the hedonic regression method with observations drawn from the top 100, 50 and 20 artists by sales volume, giving approximately 29 503 total auction observations. The Index consists of quarterly data from the period 2000Q1 to 2013Q3. A vector autoregression of the art price index, Johannesburg stock exchange all-share index, house price index, and South African government bond index were used. Results show that, when there are increased returns on the stock market in a preceding period and wealth increases, there is a change in the Citadel art price index in the same direction. No significant difference was found between the house price index and the art price index, or between the art and government bond price indices. The art market is also found to be inefficient, thereby exacerbating the risk of investing in art. Overall, the South African art market does not offer the opportunity to diversify portfolios dominated by either property, bonds, or shares.
- Full Text:
- Date Issued: 2016
- Authors: Botha, Ferdi , Snowball, Jeanette D , Scott, Brett
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64794 , vital:28601 , http://www.dx.doi.org/10.17159/2222-3436/2016/v19n3a4
- Description: Art has been suggested as a good way to diversify investment portfolios during times of financial uncertainty. The argument is that art exhibits different risk and return characteristics to conventional investments in other asset classes. The new Citadel art price index offered the opportunity to test this theory in the South African context. Moreover, this paper tests whether art prices are efficient. The Citadel index uses the hedonic regression method with observations drawn from the top 100, 50 and 20 artists by sales volume, giving approximately 29 503 total auction observations. The Index consists of quarterly data from the period 2000Q1 to 2013Q3. A vector autoregression of the art price index, Johannesburg stock exchange all-share index, house price index, and South African government bond index were used. Results show that, when there are increased returns on the stock market in a preceding period and wealth increases, there is a change in the Citadel art price index in the same direction. No significant difference was found between the house price index and the art price index, or between the art and government bond price indices. The art market is also found to be inefficient, thereby exacerbating the risk of investing in art. Overall, the South African art market does not offer the opportunity to diversify portfolios dominated by either property, bonds, or shares.
- Full Text:
- Date Issued: 2016
The good African society index
- Authors: Botha, Ferdi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396194 , vital:69157 , xlink:href="https://doi.org/10.1007/s11205-015-0891-z"
- Description: This paper constructs a Good Society Index for 45 African countries, termed the Good African Society Index (GASI). The GASI consists of nine main indexes: (1) economic sustainability, (2) democracy and freedom, (3) child well-being, (4) environment and infrastructure, (5) safety and security, (6) health and health systems, (7) integrity and justice, (8) education, and (9) social sustainability and social cohesion. Each component is split into four sub-components for a total of 36 indicators. Tunisia ranks highest on the GASI, followed by Cape Verde and Botswana. Chad has the lowest GASI score, followed by Central African Republic and Cote d’Ivoire. The GASI is strongly related to the 2012 Human Development Index and Fragile States Index, to a lesser extent, GNI per capita.
- Full Text:
- Date Issued: 2016
- Authors: Botha, Ferdi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396194 , vital:69157 , xlink:href="https://doi.org/10.1007/s11205-015-0891-z"
- Description: This paper constructs a Good Society Index for 45 African countries, termed the Good African Society Index (GASI). The GASI consists of nine main indexes: (1) economic sustainability, (2) democracy and freedom, (3) child well-being, (4) environment and infrastructure, (5) safety and security, (6) health and health systems, (7) integrity and justice, (8) education, and (9) social sustainability and social cohesion. Each component is split into four sub-components for a total of 36 indicators. Tunisia ranks highest on the GASI, followed by Cape Verde and Botswana. Chad has the lowest GASI score, followed by Central African Republic and Cote d’Ivoire. The GASI is strongly related to the 2012 Human Development Index and Fragile States Index, to a lesser extent, GNI per capita.
- Full Text:
- Date Issued: 2016