Elizabeth Costello and the Biography of the Moral Philosopher
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275635 , vital:55065 , xlink:href="https://doi.org/10.1111/j.1540-6245.2011.01462.x"
- Description: Imagine someone who informs you that her conversion to vegetarianism began when she read Charlotte's Web or viewed the film Babe. Both stories invite the reader to celebrate the events surrounding a pig being saved from the butcher. What kind of role would her spectatorship of this book or film have played in her conversion? It is perhaps improbable to suspect that she would have undergone this kind of extreme moral conversion solely on the basis of her engagement with one of these fictions; perhaps more likely is the scenario in which her engagement was only one part of a lengthy process of her moral change of mind. In any event, it is certainly possible that our imagined vegetarian would see her encounter with Charlotte's Web or Babe as playing a justificatory role in her conversion. In looking back at her conversion, she might say something like this: “I know that I was young and impressionable, but the way in which the book (or film) made me feel about its characters moved me to further reflect upon animals and the animal industry, and I now realize that it was right to do so.” On her own view, at least, her spectatorship motivated and warranted her taking the further steps that ultimately led to her conversion. If she is right, then fictional narratives can possess—to at least some degree—what Raimond Gaita refers to as an ethical “authority.”
- Full Text:
- Date Issued: 2011
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275635 , vital:55065 , xlink:href="https://doi.org/10.1111/j.1540-6245.2011.01462.x"
- Description: Imagine someone who informs you that her conversion to vegetarianism began when she read Charlotte's Web or viewed the film Babe. Both stories invite the reader to celebrate the events surrounding a pig being saved from the butcher. What kind of role would her spectatorship of this book or film have played in her conversion? It is perhaps improbable to suspect that she would have undergone this kind of extreme moral conversion solely on the basis of her engagement with one of these fictions; perhaps more likely is the scenario in which her engagement was only one part of a lengthy process of her moral change of mind. In any event, it is certainly possible that our imagined vegetarian would see her encounter with Charlotte's Web or Babe as playing a justificatory role in her conversion. In looking back at her conversion, she might say something like this: “I know that I was young and impressionable, but the way in which the book (or film) made me feel about its characters moved me to further reflect upon animals and the animal industry, and I now realize that it was right to do so.” On her own view, at least, her spectatorship motivated and warranted her taking the further steps that ultimately led to her conversion. If she is right, then fictional narratives can possess—to at least some degree—what Raimond Gaita refers to as an ethical “authority.”
- Full Text:
- Date Issued: 2011
Evaluation of the in vitro differential protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (NLCs) for potential targeting to the brain
- Kasongo, Kasongo W, Jansch, Mirko, Müller, Rainer H, Walker, Roderick B
- Authors: Kasongo, Kasongo W , Jansch, Mirko , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184035 , vital:44160 , xlink:href="https://doi.org/10.3109/08982104.2010.539186"
- Description: The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol® ATO 5 and Transcutol® HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol® HS 15 alone or with a ternary surfactant system consisting of Solutol® HS 15, Tween® 80, and Lutrol® F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween® 80 and Lutrol® F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween® 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol® HS 15–stabilized nanoparticles may also achieve a similar purpose.
- Full Text:
- Date Issued: 2011
- Authors: Kasongo, Kasongo W , Jansch, Mirko , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184035 , vital:44160 , xlink:href="https://doi.org/10.3109/08982104.2010.539186"
- Description: The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol® ATO 5 and Transcutol® HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol® HS 15 alone or with a ternary surfactant system consisting of Solutol® HS 15, Tween® 80, and Lutrol® F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween® 80 and Lutrol® F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween® 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol® HS 15–stabilized nanoparticles may also achieve a similar purpose.
- Full Text:
- Date Issued: 2011
Factors mediating personal and professional development within higher learning institutions: an activity theory perspective.
- Authors: Kriel, Denise
- Date: 2011
- Subjects: School improvement programs http://id.loc.gov/authorities/subjects/sh85118340 , Educational leadership http://id.loc.gov/authorities/subjects/sh92001254 , College administrators http://id.loc.gov/authorities/subjects/sh85028268
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19431 , vital:43086
- Description: In the context of a higher learning institution, this paper identifies the factors that mediate students‟ personal and professional development from an Activity Theory perspective. Data took the form of written reflections submitted by second-year psychology students‟ as part of their course requirements. The reflection exercises were designed to help students to use the knowledge acquired in the second-year programme to reflect on their own understanding of „self‟ and the practice of psychology in society. Data was analysed from an Activity Theory perspective and employed interpretative methodologies. The findings of the study shed light upon the role of contemporary contextual factors mediating students‟ personal and professional development at a higher learning institution. , Thesis (M Soc Sc) (Counselling Psychology) -- University of Fort Hare, 2011
- Full Text:
- Date Issued: 2011
- Authors: Kriel, Denise
- Date: 2011
- Subjects: School improvement programs http://id.loc.gov/authorities/subjects/sh85118340 , Educational leadership http://id.loc.gov/authorities/subjects/sh92001254 , College administrators http://id.loc.gov/authorities/subjects/sh85028268
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19431 , vital:43086
- Description: In the context of a higher learning institution, this paper identifies the factors that mediate students‟ personal and professional development from an Activity Theory perspective. Data took the form of written reflections submitted by second-year psychology students‟ as part of their course requirements. The reflection exercises were designed to help students to use the knowledge acquired in the second-year programme to reflect on their own understanding of „self‟ and the practice of psychology in society. Data was analysed from an Activity Theory perspective and employed interpretative methodologies. The findings of the study shed light upon the role of contemporary contextual factors mediating students‟ personal and professional development at a higher learning institution. , Thesis (M Soc Sc) (Counselling Psychology) -- University of Fort Hare, 2011
- Full Text:
- Date Issued: 2011
Formation, surface characterization, and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese, iron, and cobalt benzylthio phthalocyanine complexes
- Akinbulu, Isaac Adebayo, Ozoemena, Kenneth Iyke, Nyokong, Tebello
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
Formulation development and in vitro evaluation of didanosine-loaded nanostructured lipid carriers for the potential treatment of AIDS dementia complex
- Wa Kasongo, Kasongo, Shegokar, Ranjita, Müller, Rainer H, Walker, Roderick B
- Authors: Wa Kasongo, Kasongo , Shegokar, Ranjita , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184210 , vital:44190 , xlink:href="https://doi.org/10.3109/03639045.2010.516264"
- Description: The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol ® ATO 5 and Transcutol ® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from −18.4 to −11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.
- Full Text:
- Date Issued: 2011
- Authors: Wa Kasongo, Kasongo , Shegokar, Ranjita , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184210 , vital:44190 , xlink:href="https://doi.org/10.3109/03639045.2010.516264"
- Description: The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol ® ATO 5 and Transcutol ® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from −18.4 to −11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.
- Full Text:
- Date Issued: 2011
Heritage–A conceptually evolving and dissonant phenomenon: Implications for heritage management and education practices in post-colonial Southern Africa
- Authors: Zazu, Clayton
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387208 , vital:68215 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122250"
- Description: This conceptual paper is based on experiences and insights which have emerged from my quest to develop a conceptual framework for working with the term ‘heritage’ within an education for sustainable development study that I am currently conducting. Of specific interest to me, and having potential to improve the relevance and quality of heritage education in southern Africa, given the region’s inherent cultural diversity and colonial history, is the need for ‘heritage construct inclusivity’ within the processes constituting heritage education practices. Working around this broad research goal, I therefore needed to be clear about what I mean or refer to as heritage. I realised, however, how elusive and conceptually problematic the term ‘heritage’ is. I therefore, drawing from literature and experiences gained during field observations and focus group interviews, came up with the idea of working with three viewpoints of heritage. Drawing on real life cases I argue that current heritage management and education practices’ failure to recognise and respect the evolving, interconnectedness and multi layered nature of heritage, partly explain the same practices’ lack of relevance and agency to enhance the sustainable management of local heritage resources. I also suggest a few ideas which heritage educators in the context of post-colonial southern Africa may need to consider in their everyday heritage education practices. I also introduce the notion of conceptualising heritage as ‘cultural landscapes’, within which the evolving, dissonant and interconnected nature of heritage, and associated heritage constructs, may be reconciled.
- Full Text:
- Date Issued: 2011
- Authors: Zazu, Clayton
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387208 , vital:68215 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122250"
- Description: This conceptual paper is based on experiences and insights which have emerged from my quest to develop a conceptual framework for working with the term ‘heritage’ within an education for sustainable development study that I am currently conducting. Of specific interest to me, and having potential to improve the relevance and quality of heritage education in southern Africa, given the region’s inherent cultural diversity and colonial history, is the need for ‘heritage construct inclusivity’ within the processes constituting heritage education practices. Working around this broad research goal, I therefore needed to be clear about what I mean or refer to as heritage. I realised, however, how elusive and conceptually problematic the term ‘heritage’ is. I therefore, drawing from literature and experiences gained during field observations and focus group interviews, came up with the idea of working with three viewpoints of heritage. Drawing on real life cases I argue that current heritage management and education practices’ failure to recognise and respect the evolving, interconnectedness and multi layered nature of heritage, partly explain the same practices’ lack of relevance and agency to enhance the sustainable management of local heritage resources. I also suggest a few ideas which heritage educators in the context of post-colonial southern Africa may need to consider in their everyday heritage education practices. I also introduce the notion of conceptualising heritage as ‘cultural landscapes’, within which the evolving, dissonant and interconnected nature of heritage, and associated heritage constructs, may be reconciled.
- Full Text:
- Date Issued: 2011
In vitro toxicity testing of zinc tetrasulfophthalocyanines in fibroblast and keratinocyte cells for the treatment of melanoma cancer by photodynamic therapy
- Maduray, Kaminee, Karsten, Alta, Odhay, Bharti, Nyokong, Tebello
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
Investigating the impact of capital account liberalization on economic growth: A case study of South Africa
- Khumalo, Sibanisezwe A. (https://orcid.org/0000-0002-4330-9249)
- Authors: Khumalo, Sibanisezwe A. (https://orcid.org/0000-0002-4330-9249)
- Date: 2011
- Subjects: Capital Movements--South Africa , Investment, Foreign--South Africa South Africa , Free Trade--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25800 , vital:64486
- Description: The increased interest in capital flows has made it imperative to understand how they impact a particular economy. The Global drive for an interlinked world economy has increased the need for monetary authorities and Governments to able to effectively deal with any negative spins off from capital flows and also be able to take advantage of positive effects capital flows may have on an economy. The study seeks to understand how the change to lift restrictions on capital flows into the South African economy may have impacted on economic growth. The study analyses the relationship that existed between capital flows, that is to say foreign direct investment (FDI) and portfolio investment (P_I) and economic growth under the period of capital controls (1975 Q1 to 1994Q1). Then study will then analyse the same relationship but this time under the liberalised period (1994 Q2 to 2010 Q2) and compare how the long run relationship has changed after capital account liberalisation. The study uses an endogenous model to determine the relationship. The study unlike most will focus on a single economy, which is South Africa and not use panel data like most previous studies. The study found that in the short run capital account liberalising aided economic growth as both FDI and P_I became significant, with positive coefficients and also found that there is long run relationship between economic growth and capital flows. In the long run FDI is significant while P_I is not. After liberalisation FDI adjusted faster in the long run than before liberalisation on its impact on economic output. Also of note was that the study found that under capital controls the conditional variance was constant but after liberalisation the relationship between capital flows and economic growth became more sensitive to negative news and the conditional variance was not constant thus indication of increased volatility. To maximise from opening up of capital accounts the economy should maintain sound macroeconomic policies. This will help shield the economy from the external shocks and this maintain economic growth. , Thesis (MA) -- Faculty of Management and Commerce, 2011
- Full Text:
- Date Issued: 2011
- Authors: Khumalo, Sibanisezwe A. (https://orcid.org/0000-0002-4330-9249)
- Date: 2011
- Subjects: Capital Movements--South Africa , Investment, Foreign--South Africa South Africa , Free Trade--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25800 , vital:64486
- Description: The increased interest in capital flows has made it imperative to understand how they impact a particular economy. The Global drive for an interlinked world economy has increased the need for monetary authorities and Governments to able to effectively deal with any negative spins off from capital flows and also be able to take advantage of positive effects capital flows may have on an economy. The study seeks to understand how the change to lift restrictions on capital flows into the South African economy may have impacted on economic growth. The study analyses the relationship that existed between capital flows, that is to say foreign direct investment (FDI) and portfolio investment (P_I) and economic growth under the period of capital controls (1975 Q1 to 1994Q1). Then study will then analyse the same relationship but this time under the liberalised period (1994 Q2 to 2010 Q2) and compare how the long run relationship has changed after capital account liberalisation. The study uses an endogenous model to determine the relationship. The study unlike most will focus on a single economy, which is South Africa and not use panel data like most previous studies. The study found that in the short run capital account liberalising aided economic growth as both FDI and P_I became significant, with positive coefficients and also found that there is long run relationship between economic growth and capital flows. In the long run FDI is significant while P_I is not. After liberalisation FDI adjusted faster in the long run than before liberalisation on its impact on economic output. Also of note was that the study found that under capital controls the conditional variance was constant but after liberalisation the relationship between capital flows and economic growth became more sensitive to negative news and the conditional variance was not constant thus indication of increased volatility. To maximise from opening up of capital accounts the economy should maintain sound macroeconomic policies. This will help shield the economy from the external shocks and this maintain economic growth. , Thesis (MA) -- Faculty of Management and Commerce, 2011
- Full Text:
- Date Issued: 2011
Investigation of homogeneous photosensitized oxidation activities of palladium and platinum octasubstituted phthalocyanines
- Ogunbayo, Taofeek B, Antunes, Edith M, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
Microelectrochemical patterning of gold surfaces using 4-azidobenzenediazonium and scanning electrochemical microscopy
- Coates, Megan, Cabet, Eva, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
- Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
- Full Text:
- Date Issued: 2011
- Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
- Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
- Full Text:
- Date Issued: 2011
Optical limiting behavior of ring substituted zinc, indium and gallium phthalocyanines in the presence of quantum dots
- Britton, Jonathan, Litwinski, Christian, Durmus, Mahmut, Chauke, Vongani, Nyokong, Tebello
- Authors: Britton, Jonathan , Litwinski, Christian , Durmus, Mahmut , Chauke, Vongani , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247122 , vital:51548 , xlink:href="https://doi.org/10.1142/S1088424611004142"
- Description: This paper presents the study of the effects of CdTe-TGA quantum dots (QDs) on optical limiting ability of different phthalocyanine (Pc) complexes (1–10) containing Zn, Ga, In central metals and substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups. The optical limiting parameters of Pcs were higher for tert-butylphenoxy when compared to benzyloxyphenoxy and phenoxy substituents, in DMSO. Non-peripheral substitution decreased the optical limiting parameters. Third-order susceptibility (Im[χ(3)]/α) values of Pcs in the absence and presence of CdTe QDs were in the 10-12 to 10-10 esu.cm range. Hyperpolarizabilities (γ) ranged from 10-31 to 10-29 esu L for Pc alone or in mixture with QDs. There is a general improvement in optical limiting ability of Pc complexes in the presence of CdTe TGA QDs. Due to these promising results, future work can be implemented for the creation of Pc:QD thin films, which would then be examined to ensure that their optical limiting ability is still acceptable.
- Full Text:
- Date Issued: 2011
- Authors: Britton, Jonathan , Litwinski, Christian , Durmus, Mahmut , Chauke, Vongani , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247122 , vital:51548 , xlink:href="https://doi.org/10.1142/S1088424611004142"
- Description: This paper presents the study of the effects of CdTe-TGA quantum dots (QDs) on optical limiting ability of different phthalocyanine (Pc) complexes (1–10) containing Zn, Ga, In central metals and substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups. The optical limiting parameters of Pcs were higher for tert-butylphenoxy when compared to benzyloxyphenoxy and phenoxy substituents, in DMSO. Non-peripheral substitution decreased the optical limiting parameters. Third-order susceptibility (Im[χ(3)]/α) values of Pcs in the absence and presence of CdTe QDs were in the 10-12 to 10-10 esu.cm range. Hyperpolarizabilities (γ) ranged from 10-31 to 10-29 esu L for Pc alone or in mixture with QDs. There is a general improvement in optical limiting ability of Pc complexes in the presence of CdTe TGA QDs. Due to these promising results, future work can be implemented for the creation of Pc:QD thin films, which would then be examined to ensure that their optical limiting ability is still acceptable.
- Full Text:
- Date Issued: 2011
Optimal template removal from molecularly imprinted polymers by pressurized hot water extraction
- Batlokwa, Bareki Shima, Mokgadi, Janes, Nyokong, Tebello, Torto, Nelson
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
Optimizing the electrocatalytic activity of surface confined Co macrocyclics for the electrooxidation of thiocyanate at pH 4
- Tshangana, Charmaine, Pavez, Jorge, Gulppi, Miguel A, De Mattos, Ivanildo Luiz, Arratia-Perez, Ramiro, Linares-Flores, Cristian, Paez, Maritza, Nyokong, Tebello, Zagal, Jos H
- Authors: Tshangana, Charmaine , Pavez, Jorge , Gulppi, Miguel A , De Mattos, Ivanildo Luiz , Arratia-Perez, Ramiro , Linares-Flores, Cristian , Paez, Maritza , Nyokong, Tebello , Zagal, Jos H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247726 , vital:51612 , xlink:href="https://doi.org/10.1002/elan.201000599"
- Description: We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10−7 and 10−3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.
- Full Text:
- Date Issued: 2011
- Authors: Tshangana, Charmaine , Pavez, Jorge , Gulppi, Miguel A , De Mattos, Ivanildo Luiz , Arratia-Perez, Ramiro , Linares-Flores, Cristian , Paez, Maritza , Nyokong, Tebello , Zagal, Jos H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247726 , vital:51612 , xlink:href="https://doi.org/10.1002/elan.201000599"
- Description: We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10−7 and 10−3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.
- Full Text:
- Date Issued: 2011
Organizational commitment, age and gender effects on organizational citizenship behaviour of university employees
- Authors: Khayundi, Daniel Asiachi
- Date: 2011
- Subjects: Organizational behavior -- South Africa , Organizational effectiveness -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25755 , vital:64476
- Description: Organizational citizenship behaviour is one of the important factors that enhance organizational effectiveness. The main purpose of this study was to explore the impact of Organizational commitment on Organizational Citizenship Behaviour (OCB). In this study, age and gender effects on OCB of tertiary institution employees were also examined. The data was collected from 68 academic and administration staff from the University of Fort Hare, Alice campus through questionnaires. The results show that 68 respondents are of the view that organizational commitment impacts positively in enhancing the organizational citizenship behaviour of the employees. The findings also reveal that age and gender play no role in the practice of employees OCB. Management can increase the levels of OCB in their employees by recognizing employees who engage themselves in such behaviour. Implications that can help management in the University of Fort Hare, Alice campus in augmenting the OCB of employees is also discussed. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
- Full Text:
- Date Issued: 2011
- Authors: Khayundi, Daniel Asiachi
- Date: 2011
- Subjects: Organizational behavior -- South Africa , Organizational effectiveness -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25755 , vital:64476
- Description: Organizational citizenship behaviour is one of the important factors that enhance organizational effectiveness. The main purpose of this study was to explore the impact of Organizational commitment on Organizational Citizenship Behaviour (OCB). In this study, age and gender effects on OCB of tertiary institution employees were also examined. The data was collected from 68 academic and administration staff from the University of Fort Hare, Alice campus through questionnaires. The results show that 68 respondents are of the view that organizational commitment impacts positively in enhancing the organizational citizenship behaviour of the employees. The findings also reveal that age and gender play no role in the practice of employees OCB. Management can increase the levels of OCB in their employees by recognizing employees who engage themselves in such behaviour. Implications that can help management in the University of Fort Hare, Alice campus in augmenting the OCB of employees is also discussed. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
- Full Text:
- Date Issued: 2011
Photocatalytic behaviour of tantalum (V) phthalocyanines in the presence of gold nanoparticles towards the oxidation of cyclohexene
- Chauke, Vongani P, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
Photocatalytic transformation of chlorophenols under homogeneous and heterogeneous conditions using palladium octadodecylthio phthalocyanine
- Ogunbayo, Taofeek B, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246816 , vital:51516 , xlink:href="https://doi.org/10.1016/j.molcata.2011.09.003"
- Description: Homogeneous and heterogeneous photosensitized transformations of 4-chlorophenol (4-CP) and pentachlorophenol (PCP) using palladium octadodecylthiophthalocyanine (PdODPc) were investigated. Under heterogeneous conditions, the photosensitizer was supported on functionalized single walled carbon nanotubes (SWCNTs). Homogeneous photosensitization proved to be more effective than the heterogeneous reaction in terms of percentage of transformation achieved. The kinetics of heterogeneous catalysis proved that ads-PdODPc–SWCNT–COOH (where SWCNT has been functionalized with COOH groups) was reusable for 4-CP while its activity degenerated when reused for PCP. Singlet oxygen was confirmed as playing an active role in the reactions.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246816 , vital:51516 , xlink:href="https://doi.org/10.1016/j.molcata.2011.09.003"
- Description: Homogeneous and heterogeneous photosensitized transformations of 4-chlorophenol (4-CP) and pentachlorophenol (PCP) using palladium octadodecylthiophthalocyanine (PdODPc) were investigated. Under heterogeneous conditions, the photosensitizer was supported on functionalized single walled carbon nanotubes (SWCNTs). Homogeneous photosensitization proved to be more effective than the heterogeneous reaction in terms of percentage of transformation achieved. The kinetics of heterogeneous catalysis proved that ads-PdODPc–SWCNT–COOH (where SWCNT has been functionalized with COOH groups) was reusable for 4-CP while its activity degenerated when reused for PCP. Singlet oxygen was confirmed as playing an active role in the reactions.
- Full Text:
- Date Issued: 2011
Photophysical and photochemical behavior of electrospun fibers of a polyurethane polymer chemically linked to lutetium carboxyphenoxy phthalocyanine
- Zugle, Ruhpino, Litwinski, Christian, Torto, Nelson, Nyokong, Tebello
- Authors: Zugle, Ruhpino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruhpino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
Photophysical behavior of zinc monoaminophthalocyanines linked to mercaptopropionic acid-capped CdTe quantum dots
- D'Souza, Sarah, Antunes, Edith M, Litwinski, Christian, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
Photophysical behaviour of asymmetrically substituted metal free, Mg and Zn phthalocyanines in the presence of folic acid
- Nombona, Nolwazi, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247705 , vital:51608 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.033"
- Description: This work reports on the synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines containing a mono carboxylic acid group for possible linking to biological molecules via an amide bond. Successful synthesis of the phthalocyanines was achieved through the statistical condensation method. The phthalocyanines were mixed with folic acid and their photophysical properties were examined. The triplet quantum yield values for all the complexes in DMSO were between 0.49 and 0.74 and in the presence of folic acid they were between 0.37 and 0.63. The lifetimes were generally good ranging from 70 to 290 μs in the absence or presence of folic acid.
- Full Text:
- Date Issued: 2011
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247705 , vital:51608 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.033"
- Description: This work reports on the synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines containing a mono carboxylic acid group for possible linking to biological molecules via an amide bond. Successful synthesis of the phthalocyanines was achieved through the statistical condensation method. The phthalocyanines were mixed with folic acid and their photophysical properties were examined. The triplet quantum yield values for all the complexes in DMSO were between 0.49 and 0.74 and in the presence of folic acid they were between 0.37 and 0.63. The lifetimes were generally good ranging from 70 to 290 μs in the absence or presence of folic acid.
- Full Text:
- Date Issued: 2011
Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions
- Zugle, Ruphino, Litwinski, Christian, Nyokong, Tebello
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011