Editorial
- Schudel, Ingrid, Le Grange, Lesley, Reddy, Chris
- Authors: Schudel, Ingrid , Le Grange, Lesley , Reddy, Chris
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387193 , vital:68214 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/167508"
- Description: The unprecedented levels of human influence on the global enviroment have drawn the attention of scientists to the extent that in 2002, the Nobel Laureate, Paul Crutzen, helped in postulating a new geological epoch named the Anthropocene (Crutzen, 2002). This idea is not new and Crutzen describes an observation by an Italian geologist named Antonio Stoppani who, in 1873, spoke about an 'anthropozoic era'. Stoppani described this era as a 'new telluric force which in power and universality may be compared to the greater forces of earth' (Stoppani, 1873 in Crutzen, 2002).
- Full Text: false
- Date Issued: 2016
- Authors: Schudel, Ingrid , Le Grange, Lesley , Reddy, Chris
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387193 , vital:68214 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/167508"
- Description: The unprecedented levels of human influence on the global enviroment have drawn the attention of scientists to the extent that in 2002, the Nobel Laureate, Paul Crutzen, helped in postulating a new geological epoch named the Anthropocene (Crutzen, 2002). This idea is not new and Crutzen describes an observation by an Italian geologist named Antonio Stoppani who, in 1873, spoke about an 'anthropozoic era'. Stoppani described this era as a 'new telluric force which in power and universality may be compared to the greater forces of earth' (Stoppani, 1873 in Crutzen, 2002).
- Full Text: false
- Date Issued: 2016
Think Piece, Naked Science-Avoiding Methodolatry in an Environmental Education Context
- Authors: Price, Leigh
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387264 , vital:68220 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122255"
- Description: Research methodology is significantly political and in this think piece I try to better understand the effect of this politicisation in the production of science. The main focus of the think piece is to identify the dominant methodological discourses and analyse them using techniques borrowed from post-structuralism. From this analysis, I suggest that methodological discourses are reproduced and normalised in much the same way as discourses of, for example, sexuality, and I give examples of this from my experience as a PhD student of environmental education. I also suggest that some transgressive methodologies, such as those associated with postmodernism or participatory research, despite purporting to empower, at times also disempower. Furthermore, all of the methodologies that I analyse are, in one way or another, ‘loaded’; they cloak their agendas. From this analysis, I move towards suggesting an alternative critical realist methodology for environmental education which is naked; its agendas are clearly stated, not least because this epistemology does not lend itself to deception. An important part of this critical realist conception of methodology is the idea of ‘meta-reflexivity’ in which truth is not vulgarly pragmatic or fideistic.
- Full Text:
- Date Issued: 2013
- Authors: Price, Leigh
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387264 , vital:68220 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122255"
- Description: Research methodology is significantly political and in this think piece I try to better understand the effect of this politicisation in the production of science. The main focus of the think piece is to identify the dominant methodological discourses and analyse them using techniques borrowed from post-structuralism. From this analysis, I suggest that methodological discourses are reproduced and normalised in much the same way as discourses of, for example, sexuality, and I give examples of this from my experience as a PhD student of environmental education. I also suggest that some transgressive methodologies, such as those associated with postmodernism or participatory research, despite purporting to empower, at times also disempower. Furthermore, all of the methodologies that I analyse are, in one way or another, ‘loaded’; they cloak their agendas. From this analysis, I move towards suggesting an alternative critical realist methodology for environmental education which is naked; its agendas are clearly stated, not least because this epistemology does not lend itself to deception. An important part of this critical realist conception of methodology is the idea of ‘meta-reflexivity’ in which truth is not vulgarly pragmatic or fideistic.
- Full Text:
- Date Issued: 2013
Understanding the sexual risk behaviours of people living with different mental illnesses and their vulnerability to HIV infection
- Authors: Ndlovu, Deogracious
- Date: 2013
- Subjects: Health -- Social aspects , HIV infections
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25037 , vital:63899
- Description: This study was primarily carried out in order to assess the sexual risk behaviours of people living with mental illnesses as well as their vulnerability to HIV infection. It sets out the basic realities of the interaction between mental illness and HIV/AIDS and its impact on individuals and communities. This study explores the implications for health policy and practice, and suggests how to provide better support and assistance in the empowerment of people living with mental illness as far as HIV and AIDS is concerned, including community support. It was also the aim of this study to look into the factors that expose this group of people to HIV infection as well as to understand the link between HIV/AIDS and mental illness. It also tested the inclusion of people with mental disabilities in HIV and AIDS prevention and education programmes. The research was conducted on the basis of a qualitative research design. A semi-structured interview schedule was used in broad based interviews to gather information from caregivers or guardians of people with mental disabilities as well as the professionals in the mental health sector. The results of the research revealed that people who are living with mental illnesses are a vulnerable group as regards HIV infection. It also conveys that this group of people presents with sexual risk behaviours, which increase their vulnerability to HIV and AIDS. In addition, there are many barriers against the inclusion of this group of people in HIV and AIDS prevention and education programmes and, as a result, they are often excluded from participating in such programmes. Importantly, the findings of this study acknowledge that there is a two-fold relationship between mental illness and HIV/AIDS. It indicates that mental illnesses are still regarded as mysterious in the community and there is much stigma and discrimination towards the mentally ill, increasing their vulnerability to HIV infection. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ndlovu, Deogracious
- Date: 2013
- Subjects: Health -- Social aspects , HIV infections
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25037 , vital:63899
- Description: This study was primarily carried out in order to assess the sexual risk behaviours of people living with mental illnesses as well as their vulnerability to HIV infection. It sets out the basic realities of the interaction between mental illness and HIV/AIDS and its impact on individuals and communities. This study explores the implications for health policy and practice, and suggests how to provide better support and assistance in the empowerment of people living with mental illness as far as HIV and AIDS is concerned, including community support. It was also the aim of this study to look into the factors that expose this group of people to HIV infection as well as to understand the link between HIV/AIDS and mental illness. It also tested the inclusion of people with mental disabilities in HIV and AIDS prevention and education programmes. The research was conducted on the basis of a qualitative research design. A semi-structured interview schedule was used in broad based interviews to gather information from caregivers or guardians of people with mental disabilities as well as the professionals in the mental health sector. The results of the research revealed that people who are living with mental illnesses are a vulnerable group as regards HIV infection. It also conveys that this group of people presents with sexual risk behaviours, which increase their vulnerability to HIV and AIDS. In addition, there are many barriers against the inclusion of this group of people in HIV and AIDS prevention and education programmes and, as a result, they are often excluded from participating in such programmes. Importantly, the findings of this study acknowledge that there is a two-fold relationship between mental illness and HIV/AIDS. It indicates that mental illnesses are still regarded as mysterious in the community and there is much stigma and discrimination towards the mentally ill, increasing their vulnerability to HIV infection. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2013
- Full Text:
- Date Issued: 2013
Educators ‘Perceptions of The Implementation of The National Curriculum Statement in Mt Fletcher District of The Eastern Cape Province
- Authors: Sikhunyana, Philiswa
- Date: 2013
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2957 , vital:43114
- Description: The National Department of Education has undergone drastically changes from 1994. This study is about teacher‘s perceptions of the implementation of NCS. This study seeks to reveal the perception, feelings and the beliefs of teachers towards the implementation of the New Curriculum Statement in Mount Fletcher District of Eastern Cape Province. A mixed mode approach was conducted in this study in a form of quantitative and qualitative methods. Stratified random sampling (schools) and purposive sampling was used to draw the participants (teachers) from different High schools in Mt Fletcher. Data was analyzed following this pattern of organizing, transcribing, coding, establishing themes or categories, structuring, findings which paved way for the recommendations of this study and conclusion. The findings of this study reveals that teachers are just shooting in the dark in the sense that few teachers are implementing NCS successfully using their own methods and strategies of teaching and learning with a very limited clear understanding of the policy documents related to NCS principles while most schools and teachers are implementing through trial and error method, policy documents are just ―blue print to them as they received no clarity of them. And above all, teachers are lamenting on systematic, pedagogical and societal challenges that hindering the process of thorough implementation of NCS. Based on the findings the researcher recommends that the National Department of Education must pay attention for the Systemic challenges e.g. thorough training of teachers on methods of teaching and learning so that they can be able to understand the policies and methods of teaching and learning. She also recommends that whenever the NDoE is introducing new reforms on education, advocacy and awareness must reach the level of implementers not the understanding of the delegates. The NDoE again must pay attention to overcrowded classrooms and classes that are not conducive for teaching and learning (poor infrastructure), lack of basic and appropriate learning materials; Societal challenges e.g. Lack of parental support and Pedagogical challenges e.g. inappropriate teaching methods as well as learning and teacher support material, unqualified and under-qualified teachers, inappropriate assessment procedures, lack of support for teachers. Key words: National Curriculum statement; Teachers; Department of Education; Implementation and Perception. , Thesis (MMED) -- Faculty of Educational Sciences, 2013
- Full Text:
- Date Issued: 2013
- Authors: Sikhunyana, Philiswa
- Date: 2013
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2957 , vital:43114
- Description: The National Department of Education has undergone drastically changes from 1994. This study is about teacher‘s perceptions of the implementation of NCS. This study seeks to reveal the perception, feelings and the beliefs of teachers towards the implementation of the New Curriculum Statement in Mount Fletcher District of Eastern Cape Province. A mixed mode approach was conducted in this study in a form of quantitative and qualitative methods. Stratified random sampling (schools) and purposive sampling was used to draw the participants (teachers) from different High schools in Mt Fletcher. Data was analyzed following this pattern of organizing, transcribing, coding, establishing themes or categories, structuring, findings which paved way for the recommendations of this study and conclusion. The findings of this study reveals that teachers are just shooting in the dark in the sense that few teachers are implementing NCS successfully using their own methods and strategies of teaching and learning with a very limited clear understanding of the policy documents related to NCS principles while most schools and teachers are implementing through trial and error method, policy documents are just ―blue print to them as they received no clarity of them. And above all, teachers are lamenting on systematic, pedagogical and societal challenges that hindering the process of thorough implementation of NCS. Based on the findings the researcher recommends that the National Department of Education must pay attention for the Systemic challenges e.g. thorough training of teachers on methods of teaching and learning so that they can be able to understand the policies and methods of teaching and learning. She also recommends that whenever the NDoE is introducing new reforms on education, advocacy and awareness must reach the level of implementers not the understanding of the delegates. The NDoE again must pay attention to overcrowded classrooms and classes that are not conducive for teaching and learning (poor infrastructure), lack of basic and appropriate learning materials; Societal challenges e.g. Lack of parental support and Pedagogical challenges e.g. inappropriate teaching methods as well as learning and teacher support material, unqualified and under-qualified teachers, inappropriate assessment procedures, lack of support for teachers. Key words: National Curriculum statement; Teachers; Department of Education; Implementation and Perception. , Thesis (MMED) -- Faculty of Educational Sciences, 2013
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- Date Issued: 2013
Catalytic oxidation of thioanisole using oxovanadium (IV)‐functionalized electrospun polybenzimidazole nanofibers
- Walmsley, Ryan S, Hlangothi, Percy, Litwinski, Christian, Nyokong, Tebello, Torto, Nelson, Tshentu, Zenixole R
- Authors: Walmsley, Ryan S , Hlangothi, Percy , Litwinski, Christian , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242083 , vital:51000 , xlink:href="https://doi.org/10.1002/app.38067"
- Description: Polybenzimidazole fibers, with an average diameter of 262 nm, were produced by the process of electrospinning. These fibers were used as a solid support material for the immobilization of oxovanadium(IV) which was achieved via a reaction with vanadyl sulfate. The oxovanadium(IV)-functionalized nanofibers were used as heterogeneous catalysts for the oxidation of thioanisole under both batch and pseudo-continuous flow conditions with great success. Under batch conditions near quantitative oxidation of thioanisole was achieved in under 90 min, even after four successive catalytic reactions. Under continuous conditions, excellent conversion of thioanisole was maintained throughout the period studied at flow rates of up to 2 mLh−1. This study, therefore, proposes that electrospun polybenzimidazole nanofibers, with their small diameters, impressive chemical and thermal stability, as well as coordinating benzimidazole group, may be a desirable support material for immobilization of homogeneous catalysts.
- Full Text:
- Date Issued: 2013
- Authors: Walmsley, Ryan S , Hlangothi, Percy , Litwinski, Christian , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242083 , vital:51000 , xlink:href="https://doi.org/10.1002/app.38067"
- Description: Polybenzimidazole fibers, with an average diameter of 262 nm, were produced by the process of electrospinning. These fibers were used as a solid support material for the immobilization of oxovanadium(IV) which was achieved via a reaction with vanadyl sulfate. The oxovanadium(IV)-functionalized nanofibers were used as heterogeneous catalysts for the oxidation of thioanisole under both batch and pseudo-continuous flow conditions with great success. Under batch conditions near quantitative oxidation of thioanisole was achieved in under 90 min, even after four successive catalytic reactions. Under continuous conditions, excellent conversion of thioanisole was maintained throughout the period studied at flow rates of up to 2 mLh−1. This study, therefore, proposes that electrospun polybenzimidazole nanofibers, with their small diameters, impressive chemical and thermal stability, as well as coordinating benzimidazole group, may be a desirable support material for immobilization of homogeneous catalysts.
- Full Text:
- Date Issued: 2013
Characterization of glassy carbon electrodes modified with carbon nanotubes and iron phthalocyanine through grafting and click chemistry
- Coates, Megan, Nyokong, Tebello
- Authors: Coates, Megan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193746 , vital:45392 , xlink:href="https://doi.org/10.1016/j.electacta.2012.12.112"
- Description: A glassy carbon electrode was modified by adsorption of single-walled carbon nanotubes, followed by electrochemical grafting of 4-azidobenzenediazonium salt, which was in turn reacted with ethynylpyridine through the Sharpless “click chemistry” reaction. Thereafter, iron phthalocyanine was attached to the electrode through axial ligation to the pyridine group. The modified electrode was characterised using X-ray photoelectron spectroscopy and scanning electrochemical microscopy, and well as electrochemistry. The electrocatalytic ability of the modified electrode was tested using hydrazine as a sample analyte, and showed a significant 10-fold improvement in the detection of hydrazine compared to the surface without nanotubes, and comparable stability. The linear range for this surface was over 1.0 × 10−5 to 1.0 × 10−4 mol dm−3, with a limit of detection of 1.10 ± 0.06 μmol dm−3 and sensitivity of 15.61 μA mM−1.
- Full Text:
- Date Issued: 2013
- Authors: Coates, Megan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193746 , vital:45392 , xlink:href="https://doi.org/10.1016/j.electacta.2012.12.112"
- Description: A glassy carbon electrode was modified by adsorption of single-walled carbon nanotubes, followed by electrochemical grafting of 4-azidobenzenediazonium salt, which was in turn reacted with ethynylpyridine through the Sharpless “click chemistry” reaction. Thereafter, iron phthalocyanine was attached to the electrode through axial ligation to the pyridine group. The modified electrode was characterised using X-ray photoelectron spectroscopy and scanning electrochemical microscopy, and well as electrochemistry. The electrocatalytic ability of the modified electrode was tested using hydrazine as a sample analyte, and showed a significant 10-fold improvement in the detection of hydrazine compared to the surface without nanotubes, and comparable stability. The linear range for this surface was over 1.0 × 10−5 to 1.0 × 10−4 mol dm−3, with a limit of detection of 1.10 ± 0.06 μmol dm−3 and sensitivity of 15.61 μA mM−1.
- Full Text:
- Date Issued: 2013
The impact of the exchange rate volatility on unemployment in South Africa
- Nyahokwe, Olivia https://orcid.org/0000-0003-2903-1014
- Authors: Nyahokwe, Olivia https://orcid.org/0000-0003-2903-1014
- Date: 2013
- Subjects: Foreign exchange rates -- South Africa , Unemployment -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25580 , vital:64336
- Description: Real exchange rate volatility have important effects on production, employment and trade, so it is crucial to understand its impact on unemployment especially on a country like South Africa.This study analyses the impact of the real exchange rate volatility on unemployment and the dynamic adjustment of unemployment rate following shocks to its determinants using quarterly South African data covering the period 2000 to 2010. It begins with a review of literature on the impact of exchange rate volatility on unemployment and provides a brief updated background on the exchange rate and unemployment in South Africa. An empirical model linking the real exchange rate to unemployment is then specified. In contrast to previous analyses, this study augments the cointegration and vector autoregression (VAR) and the GARCH model including analysis with impulse response and variance decomposition analyses to provide robust long run effects and short run dynamic effects on the unemployment rate. The empirical analysis using a variety of specifications,estimation techniques, and robustness tests suggests that exchange rate volatility has a statistically and economically significant impact on employment. The variables that have been found to have a long run relationship with unemployment rate include the real exchange rate, exports ,real interest rate and the gross domestic product.The impulse response functions broadly corroborate the theoretical predictions, but only real interest rate and exports have a significant impact on unemployment in the short run. Results from the variance decompositions are largely similar to those from the impulse response analysis. The real exchange rate and exports are the only variables found to significantly explain the variation in the unemployment. The most interesting result that emerged from this analysis and is supported by previous research is that among other determinants, the real exchange rate explain the largest proportion of the variation in unemployment rate. On balance, the evidence therefore suggests that unemployment rate fluctuations are predominantly equilibrium responses to real exchange rate shocks in comparison with interest rates, economic growth and exports. , Thesis (MCom) -- Faculty of Management and Commerce, 2013
- Full Text:
- Date Issued: 2013
- Authors: Nyahokwe, Olivia https://orcid.org/0000-0003-2903-1014
- Date: 2013
- Subjects: Foreign exchange rates -- South Africa , Unemployment -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25580 , vital:64336
- Description: Real exchange rate volatility have important effects on production, employment and trade, so it is crucial to understand its impact on unemployment especially on a country like South Africa.This study analyses the impact of the real exchange rate volatility on unemployment and the dynamic adjustment of unemployment rate following shocks to its determinants using quarterly South African data covering the period 2000 to 2010. It begins with a review of literature on the impact of exchange rate volatility on unemployment and provides a brief updated background on the exchange rate and unemployment in South Africa. An empirical model linking the real exchange rate to unemployment is then specified. In contrast to previous analyses, this study augments the cointegration and vector autoregression (VAR) and the GARCH model including analysis with impulse response and variance decomposition analyses to provide robust long run effects and short run dynamic effects on the unemployment rate. The empirical analysis using a variety of specifications,estimation techniques, and robustness tests suggests that exchange rate volatility has a statistically and economically significant impact on employment. The variables that have been found to have a long run relationship with unemployment rate include the real exchange rate, exports ,real interest rate and the gross domestic product.The impulse response functions broadly corroborate the theoretical predictions, but only real interest rate and exports have a significant impact on unemployment in the short run. Results from the variance decompositions are largely similar to those from the impulse response analysis. The real exchange rate and exports are the only variables found to significantly explain the variation in the unemployment. The most interesting result that emerged from this analysis and is supported by previous research is that among other determinants, the real exchange rate explain the largest proportion of the variation in unemployment rate. On balance, the evidence therefore suggests that unemployment rate fluctuations are predominantly equilibrium responses to real exchange rate shocks in comparison with interest rates, economic growth and exports. , Thesis (MCom) -- Faculty of Management and Commerce, 2013
- Full Text:
- Date Issued: 2013
A capability approach: Its potential for transformative education research focusing on education for sustainable development and gender issues in science teacher education
- Authors: Chikunda, Charles
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387120 , vital:68208 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122266"
- Description: In this article, I use the capability approach to explore the role that the science, mathematics and technical subjects (SMTs) teacher education curriculum can play as a ‘gender conversion factor’. This comes amidst evidence that a major hindrance to the participation of girls in these disciplines is a lack of gender responsiveness in the pedagogy applied in schools. Seven teacher educators, who were purposively sampled at a Technical Teachers’ College in Zimbabwe, were the research participants. I adopted a case study design in which I used in-depth interviews, focus-group discussions and document analysis to generate data. Data was analysed deductively using predetermined themes based on an analytical tool anchored on Sen’s two, but quite distinct, aspects of freedom, that is, the opportunity aspect and the process aspect of freedom. The findings reveal that there is a limited awareness of gender issues among teacher educators, and that these issues are not being transformed into curriculum practice. All in all, it is evident that curriculum practices of SMTs teacher educators are riddled with gender blindness and so trainee teachers graduate from college without the necessary agency to deal with personal, social and environmental conversion factors that can play a role in girls converting the curriculum into functionings (beings and doings) and wider freedoms and valued beings and doings (capabilities).
- Full Text:
- Date Issued: 2013
- Authors: Chikunda, Charles
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387120 , vital:68208 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122266"
- Description: In this article, I use the capability approach to explore the role that the science, mathematics and technical subjects (SMTs) teacher education curriculum can play as a ‘gender conversion factor’. This comes amidst evidence that a major hindrance to the participation of girls in these disciplines is a lack of gender responsiveness in the pedagogy applied in schools. Seven teacher educators, who were purposively sampled at a Technical Teachers’ College in Zimbabwe, were the research participants. I adopted a case study design in which I used in-depth interviews, focus-group discussions and document analysis to generate data. Data was analysed deductively using predetermined themes based on an analytical tool anchored on Sen’s two, but quite distinct, aspects of freedom, that is, the opportunity aspect and the process aspect of freedom. The findings reveal that there is a limited awareness of gender issues among teacher educators, and that these issues are not being transformed into curriculum practice. All in all, it is evident that curriculum practices of SMTs teacher educators are riddled with gender blindness and so trainee teachers graduate from college without the necessary agency to deal with personal, social and environmental conversion factors that can play a role in girls converting the curriculum into functionings (beings and doings) and wider freedoms and valued beings and doings (capabilities).
- Full Text:
- Date Issued: 2013
Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres
- De Schoenmaker, Bert, Van de Schueren, Lien, Zugle, Ruphino, Goethals, Annelies, Westbroek, Philippe, Kiekens, Paul, Nyokong, Tebello, De Clerck, Karen
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
Surface patterning using scanning electrochemical microscopy to locally trigger a “click” chemistry reaction
- Quinton, Damien, Maringa, Audacity, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Maringa, Audacity , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241805 , vital:50971 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.021"
- Description: We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈ 10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈ 75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates.
- Full Text:
- Date Issued: 2013
- Authors: Quinton, Damien , Maringa, Audacity , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241805 , vital:50971 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.021"
- Description: We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈ 10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈ 75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates.
- Full Text:
- Date Issued: 2013
Investigation of institutions for the implementation of the Dutywa Agripark Project in Mbashe Local Municipality in Eastern Cape Province, South Africa
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Production and characterization of a bioflocculant from a consortium of bacteria belonging to the halomonas and micrococcus genera.
- Okaiyeto, Kunle (https://orcid.org/0000-0002-7211-714X)
- Authors: Okaiyeto, Kunle (https://orcid.org/0000-0002-7211-714X)
- Date: 2013
- Subjects: Flocculants , Bacteria
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26119 , vital:64917
- Description: The physicochemical properties of two bioflocculant producing bacteria; Halomonas sp. Okoh and Micrococcus sp. Leo were investigated. The optimum culture conditions for the individual species were determined. All the growth conditions examined for the individual bacteria were similar. Glucose and ammonium sulphate as sole carbon and nitrogen sources respectively resulted in optimum production of bioflocculant. The flocculating activity of the bioflocculants was stimulated when Al3+ was used as the coagulating aid under acidic medium. The information obtained from individual strains was used to produce a bioflocculant from the consortium of the two bacteria. After purification, the bioflocculant yields from 1L fermentation broths were 1.213 g from Halomonas sp. Okoh, 0.738 g from Micrococcus sp. Leo and 3.51 g from the consortium. The chemical analyses of the purified bioflocculants showed that they were glycoproteins. The thermostability property of the bioflocculants was investigated between 50-100oC and the results revealed that they are heat-stable. Fourier transform infrared revealed the presence of hydroxyl, carboxyl and amino groups in the bioflocculant molecules. Scaning electron microscope (SEM) images showed the structure of each bioflocculant(s) and kaolin clay before and after flocculation. From the results obtained, the idea of using the two strains in consortium for bioflocculant production resulted in an improvement in terms of flocculating activity and yield. The bioflocculants appears to have promise as an alternative to chemical flocculants used in various industrial processes such as wastewater treatment and drinking water purification. , Thesis (MA) -- Faculty Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Okaiyeto, Kunle (https://orcid.org/0000-0002-7211-714X)
- Date: 2013
- Subjects: Flocculants , Bacteria
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26119 , vital:64917
- Description: The physicochemical properties of two bioflocculant producing bacteria; Halomonas sp. Okoh and Micrococcus sp. Leo were investigated. The optimum culture conditions for the individual species were determined. All the growth conditions examined for the individual bacteria were similar. Glucose and ammonium sulphate as sole carbon and nitrogen sources respectively resulted in optimum production of bioflocculant. The flocculating activity of the bioflocculants was stimulated when Al3+ was used as the coagulating aid under acidic medium. The information obtained from individual strains was used to produce a bioflocculant from the consortium of the two bacteria. After purification, the bioflocculant yields from 1L fermentation broths were 1.213 g from Halomonas sp. Okoh, 0.738 g from Micrococcus sp. Leo and 3.51 g from the consortium. The chemical analyses of the purified bioflocculants showed that they were glycoproteins. The thermostability property of the bioflocculants was investigated between 50-100oC and the results revealed that they are heat-stable. Fourier transform infrared revealed the presence of hydroxyl, carboxyl and amino groups in the bioflocculant molecules. Scaning electron microscope (SEM) images showed the structure of each bioflocculant(s) and kaolin clay before and after flocculation. From the results obtained, the idea of using the two strains in consortium for bioflocculant production resulted in an improvement in terms of flocculating activity and yield. The bioflocculants appears to have promise as an alternative to chemical flocculants used in various industrial processes such as wastewater treatment and drinking water purification. , Thesis (MA) -- Faculty Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Factors which Influence English Language Pass Rate at Matric Level in the Engcobo District of The Eastern Cape of South Africa
- Songwaxa, Nokuthula Patience
- Authors: Songwaxa, Nokuthula Patience
- Date: 2013
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3517 , vital:43622
- Description: This study investigates the management of English teaching to improve matriculation pass-rate in selected schools in the Engcobo District of the Eastern Cape of South Africa. The study has been circuits of the Engcobo district. Questionnaires were administered over a group of matriculants, English second language teachers and 8 school principals with a variety of questions and interviews on the causes of this failure problem. Based on the study it has been reared through collect data that some teachers have not been workshopped in the current curriculum (NCS) and this somehow affects the learners. Learners from rural areas have a problem in understanding English language. Lack of educational facilities like libraries also have a negative impact in learner’s progress. Learners who came from Junior Secondary Schools to High schools are not ready and this gives High School teachers a big task to mould them to be ready for matric. It is recommended that parental involvement is vital in their children’s education so as to see their progress and to develop the teacher-parent locomotives learners need to be engaged in Educational activities like debates, public speaking, conducting so as to improve their communication skills. Educators should give more writing and reading exercises to learners so as to minimize the number of learners who are unable to write in Matric. , Thesis (MMED) -- Faculty of Educational Sciences, 2013
- Full Text:
- Date Issued: 2013
- Authors: Songwaxa, Nokuthula Patience
- Date: 2013
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3517 , vital:43622
- Description: This study investigates the management of English teaching to improve matriculation pass-rate in selected schools in the Engcobo District of the Eastern Cape of South Africa. The study has been circuits of the Engcobo district. Questionnaires were administered over a group of matriculants, English second language teachers and 8 school principals with a variety of questions and interviews on the causes of this failure problem. Based on the study it has been reared through collect data that some teachers have not been workshopped in the current curriculum (NCS) and this somehow affects the learners. Learners from rural areas have a problem in understanding English language. Lack of educational facilities like libraries also have a negative impact in learner’s progress. Learners who came from Junior Secondary Schools to High schools are not ready and this gives High School teachers a big task to mould them to be ready for matric. It is recommended that parental involvement is vital in their children’s education so as to see their progress and to develop the teacher-parent locomotives learners need to be engaged in Educational activities like debates, public speaking, conducting so as to improve their communication skills. Educators should give more writing and reading exercises to learners so as to minimize the number of learners who are unable to write in Matric. , Thesis (MMED) -- Faculty of Educational Sciences, 2013
- Full Text:
- Date Issued: 2013
Opening up global food trade to developing countries: an evaluation of the World Trade Organisation's agreement on sanitary and phytosanitary measure
- Authors: Nyatsanza, Sharon
- Date: 2013
- Subjects: World Trade Organization , Food contamination , Food handling -- Safety measures
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27413 , vital:67294
- Description: Food safety and consumer protection has been a major concern of regulators since the 12th century. Sanitary and Phytosanitary (SPS) measures were therefore introduced to protect human, animal and plant safety. With the expansion of international trade came the increase in the use of SPS measures. However these increases in the use of SPS measures were accompanied with their misuse for protectionist purposes. SPS measures which had been created for legitimate purposes quickly became significant barriers to trade. The World Trade Organisation (WTO) adopted the WTO Agreement on Sanitary and Phytosanitary Measures (SPS Agreement) as a mechanism to regulate the use of SPS measures and avoid their potential use as protectionist tools. Trade liberalization and market access has been a primary aim of the WTO, therefore in principle the SPS Agreement is supposed to open up global food trade for all countries.Apart from opening up global food trade, another purpose of the SPS Agreement was to protect the developing countries, accommodate their special needs and in turn promote their economic development. Developing countries are heavily dependent on global food trade for their economic development. However developing states can only benefit from global food trade if they comply with SPS standards set in the importing countries. Considering their reliance on the agro – food sector the economic development of developing states is heavily reliant on the successful implementation of the SPS Agreement. According the SPS Agreement must avoid the use of illegitimate SPS measures and promote market access. It is therefore crucial that the SPS Agreement be analysed to determine whether its text, application and or interpretation satisfies the objective of opening up global food trade especially for developing states. The objective is to show the significance of a regulatory framework that is as much as possible devoid of any loopholes or shortcomings, which could frustrate the developmental interests. Inappropriate accommodation of developmental interests in the SPS Agreement could have adverse impacts on the development prospectus of developing countries. , Thesis (LLM) -- Faculty of Law, 2013
- Full Text:
- Date Issued: 2013
- Authors: Nyatsanza, Sharon
- Date: 2013
- Subjects: World Trade Organization , Food contamination , Food handling -- Safety measures
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27413 , vital:67294
- Description: Food safety and consumer protection has been a major concern of regulators since the 12th century. Sanitary and Phytosanitary (SPS) measures were therefore introduced to protect human, animal and plant safety. With the expansion of international trade came the increase in the use of SPS measures. However these increases in the use of SPS measures were accompanied with their misuse for protectionist purposes. SPS measures which had been created for legitimate purposes quickly became significant barriers to trade. The World Trade Organisation (WTO) adopted the WTO Agreement on Sanitary and Phytosanitary Measures (SPS Agreement) as a mechanism to regulate the use of SPS measures and avoid their potential use as protectionist tools. Trade liberalization and market access has been a primary aim of the WTO, therefore in principle the SPS Agreement is supposed to open up global food trade for all countries.Apart from opening up global food trade, another purpose of the SPS Agreement was to protect the developing countries, accommodate their special needs and in turn promote their economic development. Developing countries are heavily dependent on global food trade for their economic development. However developing states can only benefit from global food trade if they comply with SPS standards set in the importing countries. Considering their reliance on the agro – food sector the economic development of developing states is heavily reliant on the successful implementation of the SPS Agreement. According the SPS Agreement must avoid the use of illegitimate SPS measures and promote market access. It is therefore crucial that the SPS Agreement be analysed to determine whether its text, application and or interpretation satisfies the objective of opening up global food trade especially for developing states. The objective is to show the significance of a regulatory framework that is as much as possible devoid of any loopholes or shortcomings, which could frustrate the developmental interests. Inappropriate accommodation of developmental interests in the SPS Agreement could have adverse impacts on the development prospectus of developing countries. , Thesis (LLM) -- Faculty of Law, 2013
- Full Text:
- Date Issued: 2013
Land claims and the pursuit of co-management on four protected areas in South Africa
- Cundill, Georgina, Thondhlana, Gladman, Sisitka, Lawrence, Shackleton, Sheona, Blorea, M
- Authors: Cundill, Georgina , Thondhlana, Gladman , Sisitka, Lawrence , Shackleton, Sheona , Blorea, M
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391223 , vital:68632 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.05.016"
- Description: Successful land claims on protected areas by previously disenfranchised communities often result in co-management agreements between claimant communities and state conservation agencies. South Africa, in particular, has pursued co-management as the desired outcome of land claims on its protected areas. We review four cases of co-management on protected areas in South Africa, and reflect on the appropriateness of the pursuit of co-management as the preferred outcome of land claims. Despite promises of pro-poor, democratically informed management, the practical experience of co-management has seen the continuation of the status quo in terms of conservation, with very few material benefits for claimant communities and limited sharing of responsibilities and decision-making functions. The findings underscore two deep challenges facing co-management in cases of land claims worldwide. First, during land claims negotiations in cases involving protected areas, the state cannot be expected to represent the best interests of its citizens (the land claimants), while simultaneously seeking to meet national and international obligations for protected area coverage. Second, the concept of democratic co-management may sit uncomfortably beside the realities of managing loss-making protected areas with ever-shrinking conservation budgets. Where co-management agreements have already been signed, ensuring that new landowners do indeed have a say in management should form the driving focus for co-management practice going forward.
- Full Text:
- Date Issued: 2013
- Authors: Cundill, Georgina , Thondhlana, Gladman , Sisitka, Lawrence , Shackleton, Sheona , Blorea, M
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391223 , vital:68632 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.05.016"
- Description: Successful land claims on protected areas by previously disenfranchised communities often result in co-management agreements between claimant communities and state conservation agencies. South Africa, in particular, has pursued co-management as the desired outcome of land claims on its protected areas. We review four cases of co-management on protected areas in South Africa, and reflect on the appropriateness of the pursuit of co-management as the preferred outcome of land claims. Despite promises of pro-poor, democratically informed management, the practical experience of co-management has seen the continuation of the status quo in terms of conservation, with very few material benefits for claimant communities and limited sharing of responsibilities and decision-making functions. The findings underscore two deep challenges facing co-management in cases of land claims worldwide. First, during land claims negotiations in cases involving protected areas, the state cannot be expected to represent the best interests of its citizens (the land claimants), while simultaneously seeking to meet national and international obligations for protected area coverage. Second, the concept of democratic co-management may sit uncomfortably beside the realities of managing loss-making protected areas with ever-shrinking conservation budgets. Where co-management agreements have already been signed, ensuring that new landowners do indeed have a say in management should form the driving focus for co-management practice going forward.
- Full Text:
- Date Issued: 2013
Third order nonlinear optical properties of phthalocyanines in the presence nanomaterials and in polymer thin films
- Britton, Jonathan, Durmus, Mahmut, Khene, Samson M, Chauke, Vongani, Nyokong, Tebello
- Authors: Britton, Jonathan , Durmus, Mahmut , Khene, Samson M , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241772 , vital:50968 , xlink:href="https://doi.org/10.1142/S108842461350003X"
- Description: Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In, Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS, CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.
- Full Text:
- Date Issued: 2013
- Authors: Britton, Jonathan , Durmus, Mahmut , Khene, Samson M , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241772 , vital:50968 , xlink:href="https://doi.org/10.1142/S108842461350003X"
- Description: Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In, Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS, CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.
- Full Text:
- Date Issued: 2013
Synthesis and nonlinear optical examination of 3 (4), 15 (16)-Bis-(4-tert-butyl-phenoxy)-10, 22-diaminohemiporphyrazinato chloroindium
- Britton, Jonathan, Antunes, Edith M, Nyokong, Tebello
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241739 , vital:50965 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.05.001"
- Description: 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium hemiporphyrazine was synthesized from 1,3,5-triaminobenzene and 4-tert-butyl-phenoxyisoindoline. The structure of the complex was confirmed using mass, nuclear magnetic resonance and infrared spectroscopies. The nonlinear parameters of the compound was also analyzed in dimethylformamide and found to be significantly greater than previously analyzed phthalocyanines.
- Full Text:
- Date Issued: 2013
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241739 , vital:50965 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.05.001"
- Description: 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium hemiporphyrazine was synthesized from 1,3,5-triaminobenzene and 4-tert-butyl-phenoxyisoindoline. The structure of the complex was confirmed using mass, nuclear magnetic resonance and infrared spectroscopies. The nonlinear parameters of the compound was also analyzed in dimethylformamide and found to be significantly greater than previously analyzed phthalocyanines.
- Full Text:
- Date Issued: 2013
Optical limiting analysis of phthalocyanines in polymer thin films
- Britton, Jonathan, Litwinski, Christian, Antunes, Edith M, Durmus, Mahmut, Chaukea, Vongani, Nyokong, Tebello
- Authors: Britton, Jonathan , Litwinski, Christian , Antunes, Edith M , Durmus, Mahmut , Chaukea, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232488 , vital:49996 , xlink:href="https://doi.org/10.1080/10601325.2013.736269"
- Description: This paper reports on the effect of embedding twelve phthalocyanines containing In, Ga, Zn and Al as central metals in polymer thin films on their optical limiting abilities. This paper also examines the effect of forming a covalent link between zinc tetraamino phthalocyanine (10) and poly (methyl acrylic acid) (PMAA), and Zn (11) or OHAl (12) octacarboxy phthalocyanines with polyethylenimine (PEI). The average film thickness (for phthalocyanines mixed or linked to polymers) of each Pc/Polymer films on glass was 95 μm. The hyperpolarizability of the twelve phthalocyanines was found to be in the range of 10−26 to 10−24 esu.L. This is significantly higher than the hyperpolarizabilities of these phthalocyanines in solution, which ranged from 10−30 to 10−26 esu.L. Degradation studies seem to indicate that placing a phthalocyanine within a polymer thin film may protect it slightly from photo- and thermal degradation.
- Full Text:
- Date Issued: 2013
- Authors: Britton, Jonathan , Litwinski, Christian , Antunes, Edith M , Durmus, Mahmut , Chaukea, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232488 , vital:49996 , xlink:href="https://doi.org/10.1080/10601325.2013.736269"
- Description: This paper reports on the effect of embedding twelve phthalocyanines containing In, Ga, Zn and Al as central metals in polymer thin films on their optical limiting abilities. This paper also examines the effect of forming a covalent link between zinc tetraamino phthalocyanine (10) and poly (methyl acrylic acid) (PMAA), and Zn (11) or OHAl (12) octacarboxy phthalocyanines with polyethylenimine (PEI). The average film thickness (for phthalocyanines mixed or linked to polymers) of each Pc/Polymer films on glass was 95 μm. The hyperpolarizability of the twelve phthalocyanines was found to be in the range of 10−26 to 10−24 esu.L. This is significantly higher than the hyperpolarizabilities of these phthalocyanines in solution, which ranged from 10−30 to 10−26 esu.L. Degradation studies seem to indicate that placing a phthalocyanine within a polymer thin film may protect it slightly from photo- and thermal degradation.
- Full Text:
- Date Issued: 2013
Poly methyl methacrylate films containing metallophthalocyanines in the presence of CdTe quantum dots
- Britton, Jonathan, Durmus, Mahmut, Chauke, Vongani, Nyokong, Tebello
- Authors: Britton, Jonathan , Durmus, Mahmut , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241629 , vital:50956 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.09.017"
- Description: Non-linear optical (NLO) parameters were determined for phthalocyanine complexes containing In, Ga and Zn as central metals when embedded in poly (methyl methacrylate) polymer in the absence and presence of quantum dots (QDs) in an effort to create the most optimal optical limiting material. The QDs employed were CdTe–TGA (TGA = thioglylcolic acid). Triplet lifetimes generally increased as the value of the ratio of absorption cross sections of the excited state to that of the ground state (k) decreased on addition of CdTe–TGA to the phthalocyanines. The saturation energy density (Fsat) values were generally smaller in the films when compared to the solutions. Fsat, Ilim, Im[χ(3)]/α and γ all gave values which were of optimal range (i.e. the Im[χ(3)]/α and γ values were high enough to ensure adequate optical limiting but not too high to make the compounds behave like optical filters. Also, the Fsat and Ilim values were small enough to mean that the optical limiting process started at an intensity which was not too high) for complex 10 containing Zn central metal and tetrasubstituted with amino groups.
- Full Text:
- Date Issued: 2013
- Authors: Britton, Jonathan , Durmus, Mahmut , Chauke, Vongani , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241629 , vital:50956 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.09.017"
- Description: Non-linear optical (NLO) parameters were determined for phthalocyanine complexes containing In, Ga and Zn as central metals when embedded in poly (methyl methacrylate) polymer in the absence and presence of quantum dots (QDs) in an effort to create the most optimal optical limiting material. The QDs employed were CdTe–TGA (TGA = thioglylcolic acid). Triplet lifetimes generally increased as the value of the ratio of absorption cross sections of the excited state to that of the ground state (k) decreased on addition of CdTe–TGA to the phthalocyanines. The saturation energy density (Fsat) values were generally smaller in the films when compared to the solutions. Fsat, Ilim, Im[χ(3)]/α and γ all gave values which were of optimal range (i.e. the Im[χ(3)]/α and γ values were high enough to ensure adequate optical limiting but not too high to make the compounds behave like optical filters. Also, the Fsat and Ilim values were small enough to mean that the optical limiting process started at an intensity which was not too high) for complex 10 containing Zn central metal and tetrasubstituted with amino groups.
- Full Text:
- Date Issued: 2013
Perceptions and use of public green space is influenced by its relative abundance in two small towns in South Africa
- Shackleton, Charlie M, Blair, Andrew
- Authors: Shackleton, Charlie M , Blair, Andrew
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181026 , vital:43688 , xlink:href="https://doi.org/10.1016/j.landurbplan.2013.01.011"
- Description: The challenges in planning and maintaining urban public green spaces in poor towns of the developing world differ markedly from those of the developed world. This paper reports on residents’ perceptions, use and willingness to get involved in urban public green space (PGS) issues in two poor towns in South Africa which differed markedly in the amount of PGS. The disparities in PGS between the two towns were also replicated in different suburbs within the two towns. We hypothesised that levels of dissatisfaction would be highest in those suburbs and the town with the least PGS. The results indicated that the distance from residents’ homesteads to the nearest PGS was similar across towns and suburbs. Most residents felt that having accessible PGS was important, and the majority agreed that there was insufficient PGS in their respective town and suburb, and that the local municipality did not do enough in providing PGS or maintaining what there was. The level of dissatisfaction with the amount and condition of PGS was generally highest in the suburbs and town with the least PGS. Many felt that the municipality had insufficient commitment and funds to adequately maintain PGS, and consequently the willingness of residents to get involved through either a commitment of time or funds was high. The more affluent town and suburbs were willing to pay more than the poorer ones, and the poorer ones were willing to provide more time than the more affluent ones.
- Full Text:
- Date Issued: 2013
- Authors: Shackleton, Charlie M , Blair, Andrew
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181026 , vital:43688 , xlink:href="https://doi.org/10.1016/j.landurbplan.2013.01.011"
- Description: The challenges in planning and maintaining urban public green spaces in poor towns of the developing world differ markedly from those of the developed world. This paper reports on residents’ perceptions, use and willingness to get involved in urban public green space (PGS) issues in two poor towns in South Africa which differed markedly in the amount of PGS. The disparities in PGS between the two towns were also replicated in different suburbs within the two towns. We hypothesised that levels of dissatisfaction would be highest in those suburbs and the town with the least PGS. The results indicated that the distance from residents’ homesteads to the nearest PGS was similar across towns and suburbs. Most residents felt that having accessible PGS was important, and the majority agreed that there was insufficient PGS in their respective town and suburb, and that the local municipality did not do enough in providing PGS or maintaining what there was. The level of dissatisfaction with the amount and condition of PGS was generally highest in the suburbs and town with the least PGS. Many felt that the municipality had insufficient commitment and funds to adequately maintain PGS, and consequently the willingness of residents to get involved through either a commitment of time or funds was high. The more affluent town and suburbs were willing to pay more than the poorer ones, and the poorer ones were willing to provide more time than the more affluent ones.
- Full Text:
- Date Issued: 2013