in a park in Europe
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229851 , vital:49717 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229851 , vital:49717 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
consumed society
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229840 , vital:49716 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
- Authors: Krueger, Anton
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229840 , vital:49716 , xlink:href="https://hdl.handle.net/10520/EJC47802"
- Full Text:
- Date Issued: 2008
Reading Conference recommendations in a wider context of social change
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373792 , vital:66723 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122783"
- Description: This short Viewpoint paper considers the role and value of conference recommendations in shaping the field of environmental education. It explores the social politics, and often contested nature, of conference recommendations and their institutional histories, arguing that the act of producing conference recommendations forms part of the practices of new social movements. The paper recommends historicising conference recommendations and OEcross readings‚ to consider changing discourses and new developments in the field. Accompanying the short Viewpoint paper, are two sets of recently produced conference recommendations, one from the 4th International Environmental Education Conference held in Ahmedabad, India, and the other from the 1st International Conference on Mainstreaming Environment and Sustainability in African Universities held in Nairobi, Kenya.
- Full Text:
- Date Issued: 2008
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373792 , vital:66723 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122783"
- Description: This short Viewpoint paper considers the role and value of conference recommendations in shaping the field of environmental education. It explores the social politics, and often contested nature, of conference recommendations and their institutional histories, arguing that the act of producing conference recommendations forms part of the practices of new social movements. The paper recommends historicising conference recommendations and OEcross readings‚ to consider changing discourses and new developments in the field. Accompanying the short Viewpoint paper, are two sets of recently produced conference recommendations, one from the 4th International Environmental Education Conference held in Ahmedabad, India, and the other from the 1st International Conference on Mainstreaming Environment and Sustainability in African Universities held in Nairobi, Kenya.
- Full Text:
- Date Issued: 2008
Environmental Education and Educational Quality and Relevance-Opening the debate
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182668 , vital:43852 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122756"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) tackles a critical issue being debated across the world today, namely the question of educational quality and relevance. In 2005 the UNESCO Education for All Global Monitoring Report entitled Education for All: The Quality Imperative (UNESCO, 2004) was published. This global monitoring report drew attention to issues of educational quality, and raised the problem that physical access to education does not necessarily lead to epistemological access to knowledge or to relevant education being offered to learners. In the foreword to the 430-page assessment of educational quality issues, Koïchiro Matsuura, Director General of UNESCO, stated that ‘although much debate surrounds attempts to define educational quality, solid common ground exists … Quality must be seen in light of how societies define the purpose of education’ (UNESCO, 2004: Foreword). He went on to explain that there seem to be two mutually agreed upon purposes for education in the world today: cognitive development of learners, and creative and emotional growth of learners to help them acquire values and attitudes for responsible citizenship. He also pointed out that ‘quality must pass the test of equity’ (UNESCO, 2004: Foreword), emphasising the importance of equity of opportunity to access and participate in education and learning. Relevant to the field of environmental education, is the inclusion of educational quality as a major thrust of the United Nations Decade of Education for Sustainable Development (UNDESD) (UNESCO, 2004).
- Full Text:
- Date Issued: 2008
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182668 , vital:43852 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122756"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) tackles a critical issue being debated across the world today, namely the question of educational quality and relevance. In 2005 the UNESCO Education for All Global Monitoring Report entitled Education for All: The Quality Imperative (UNESCO, 2004) was published. This global monitoring report drew attention to issues of educational quality, and raised the problem that physical access to education does not necessarily lead to epistemological access to knowledge or to relevant education being offered to learners. In the foreword to the 430-page assessment of educational quality issues, Koïchiro Matsuura, Director General of UNESCO, stated that ‘although much debate surrounds attempts to define educational quality, solid common ground exists … Quality must be seen in light of how societies define the purpose of education’ (UNESCO, 2004: Foreword). He went on to explain that there seem to be two mutually agreed upon purposes for education in the world today: cognitive development of learners, and creative and emotional growth of learners to help them acquire values and attitudes for responsible citizenship. He also pointed out that ‘quality must pass the test of equity’ (UNESCO, 2004: Foreword), emphasising the importance of equity of opportunity to access and participate in education and learning. Relevant to the field of environmental education, is the inclusion of educational quality as a major thrust of the United Nations Decade of Education for Sustainable Development (UNDESD) (UNESCO, 2004).
- Full Text:
- Date Issued: 2008
Underlying mechanisms affecting institutionalisation of environmental education courses in Southern Africa
- Authors: Lupele, Justin
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386926 , vital:68188 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122773"
- Description: This paper discusses the underlying causal mechanisms that enabled or constrained institutionalisation of environmental education in 12 institutions in eight countries in southern Africa. The study was carried out in the context of the Southern Africa Development Community Regional Environmental Education Support Programme’s Course Development Network (CDN). This paper reports on part of the author's doctoral study and draws on critical realism as the ontological lens. Data analysis was done by means of a retroductive mode of inference, as articulated by Danermark, Ekström, Jakosben and Karlsson (2002). The paper demonstrates that there are a number of underlying causal mechanisms, which may enable or constrain institutionalisation of environmental education. They include factors at play at both national and institutional level; namely, responsiveness to national and institutional needs, recognition and ownership, accreditation and certification, institutional culture and politics, short course support structure and support from colleagues. As part of the discussions of the results of the study, I have advanced some retroductive theories that suggest causal mechanisms beyond the empirical data based on the participants’ experiences and events in the CDN.
- Full Text:
- Date Issued: 2008
- Authors: Lupele, Justin
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386926 , vital:68188 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122773"
- Description: This paper discusses the underlying causal mechanisms that enabled or constrained institutionalisation of environmental education in 12 institutions in eight countries in southern Africa. The study was carried out in the context of the Southern Africa Development Community Regional Environmental Education Support Programme’s Course Development Network (CDN). This paper reports on part of the author's doctoral study and draws on critical realism as the ontological lens. Data analysis was done by means of a retroductive mode of inference, as articulated by Danermark, Ekström, Jakosben and Karlsson (2002). The paper demonstrates that there are a number of underlying causal mechanisms, which may enable or constrain institutionalisation of environmental education. They include factors at play at both national and institutional level; namely, responsiveness to national and institutional needs, recognition and ownership, accreditation and certification, institutional culture and politics, short course support structure and support from colleagues. As part of the discussions of the results of the study, I have advanced some retroductive theories that suggest causal mechanisms beyond the empirical data based on the participants’ experiences and events in the CDN.
- Full Text:
- Date Issued: 2008
Photocatalytic transformation of 4-nitrophenol in aqueous media using suspended, water-insoluble metallophthalocyanine complexes
- Marais, Eloise, Antunes, Edith M, Nyokong, Tebello
- Authors: Marais, Eloise , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265986 , vital:53907 , xlink:href="https://doi.org/10.1080/00958970802146056"
- Description: Unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring substituted zinc tetranitro (ZnPc(NO2)4), zinc tetraamino (ZnPc(NH2)4), zinc hexadecafluoro (ZnPcF16) and zinc hexadecachloro (ZnPcCl16), phthalocyanine complexes are employed as photocatalysts for the heterogeneous transformation of 4-nitrophenol (4-Np) to fumaric acid and 4-nitrocatechol. ClAlPc is the best catalyst, with 89 ± 8% degradation of 4-Np after 100 min. The least effective catalysts were ZnPcCl16 and MgPc.
- Full Text:
- Date Issued: 2008
- Authors: Marais, Eloise , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265986 , vital:53907 , xlink:href="https://doi.org/10.1080/00958970802146056"
- Description: Unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring substituted zinc tetranitro (ZnPc(NO2)4), zinc tetraamino (ZnPc(NH2)4), zinc hexadecafluoro (ZnPcF16) and zinc hexadecachloro (ZnPcCl16), phthalocyanine complexes are employed as photocatalysts for the heterogeneous transformation of 4-nitrophenol (4-Np) to fumaric acid and 4-nitrocatechol. ClAlPc is the best catalyst, with 89 ± 8% degradation of 4-Np after 100 min. The least effective catalysts were ZnPcCl16 and MgPc.
- Full Text:
- Date Issued: 2008
Adsorption of 4-nitrophenol onto Amberlite® IRA-900 modified with metallophthalocyanines
- Marais, Eloïse, Nyokong, Tebello
- Authors: Marais, Eloïse , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268576 , vital:54211 , xlink:href="https://doi.org/10.1016/j.jhazmat.2007.06.096"
- Description: The adsorption of 4-nitrophenol using commercially available Amberlite® IRA-900 modified with metal phthalocyanines (MPc) was investigated. The metallophthalocyanines immobilised onto the surface of Amberlite® IRA-900 include Fe (FePcS4), Co (CoPcS4) and Ni (NiPcS4) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcSmix), Co (CoPcSmix) and Ni (NiPcSmix). Adsorption rates were fastest for the modified adsorbents at a loading of 1 × 10−3 g MPc/g Amberlite, at pH 9. The highest amount of 4-NP removal was obtained on FePcSmix modified Amberlite® IRA-900 with Qt = 42.9 mmol g−1 and adsorption efficiency of 86%. The recovery efficiency of 4-NP within 150 min was 76%. Using the Langmuir–Hinshelwood kinetic model, the complexes showed an order of 4-nitrophenol adsorption to be as follows: CoPcSmix > NiPcS4 > NiPcSmix > FePcS4 > FePcSmix > CoPcS4. The MPc modified Amberlite® IRA-900 was used repeatedly, following removal of 4-NP by nitric acid, without any significant loss of activity.
- Full Text:
- Date Issued: 2008
- Authors: Marais, Eloïse , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268576 , vital:54211 , xlink:href="https://doi.org/10.1016/j.jhazmat.2007.06.096"
- Description: The adsorption of 4-nitrophenol using commercially available Amberlite® IRA-900 modified with metal phthalocyanines (MPc) was investigated. The metallophthalocyanines immobilised onto the surface of Amberlite® IRA-900 include Fe (FePcS4), Co (CoPcS4) and Ni (NiPcS4) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcSmix), Co (CoPcSmix) and Ni (NiPcSmix). Adsorption rates were fastest for the modified adsorbents at a loading of 1 × 10−3 g MPc/g Amberlite, at pH 9. The highest amount of 4-NP removal was obtained on FePcSmix modified Amberlite® IRA-900 with Qt = 42.9 mmol g−1 and adsorption efficiency of 86%. The recovery efficiency of 4-NP within 150 min was 76%. Using the Langmuir–Hinshelwood kinetic model, the complexes showed an order of 4-nitrophenol adsorption to be as follows: CoPcSmix > NiPcS4 > NiPcSmix > FePcS4 > FePcSmix > CoPcS4. The MPc modified Amberlite® IRA-900 was used repeatedly, following removal of 4-NP by nitric acid, without any significant loss of activity.
- Full Text:
- Date Issued: 2008
Electrochemical Characterization of Self-Assembled Monolayer of a Novel Manganese Tetrabenzylthio-Substituted Phthalocyanine and Its Use in Nitrite Oxidation
- Matemadombo, Fungisai, Griveau, Sophie, Bedioui, Fethi, Nyokong, Tebello
- Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
- Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
- Full Text:
- Date Issued: 2008
- Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
- Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
- Full Text:
- Date Issued: 2008
Synthesis and electrochemical characterisation of a near infrared absorbing oxo vanadium (IV) octapentylthio-phthalocyanine
- Mbambisa, Gcineka, Nyokong, Tebello
- Authors: Mbambisa, Gcineka , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266008 , vital:53909 , xlink:href="https://doi.org/10.1016/j.poly.2008.06.004"
- Description: The synthesis of an α-substituted phthalocyanine oxo vanadium(IV) 1,4,8,11,15,18,22,25-octapentathiophthalocyanine (4) which absorbs at 850 nm in dichloromethane is reported. The complex is purple in colour and becomes green on reduction. The cyclic and square wave voltammetries of the complex show five redox couples. The spectroelectrochemical data showed only ring based processes. The ring reduced species is observed at wavelengths greater than 680 nm rather than the usual 500–600 nm range typical of ring reduced phthalocyanine complexes.
- Full Text:
- Date Issued: 2008
- Authors: Mbambisa, Gcineka , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266008 , vital:53909 , xlink:href="https://doi.org/10.1016/j.poly.2008.06.004"
- Description: The synthesis of an α-substituted phthalocyanine oxo vanadium(IV) 1,4,8,11,15,18,22,25-octapentathiophthalocyanine (4) which absorbs at 850 nm in dichloromethane is reported. The complex is purple in colour and becomes green on reduction. The cyclic and square wave voltammetries of the complex show five redox couples. The spectroelectrochemical data showed only ring based processes. The ring reduced species is observed at wavelengths greater than 680 nm rather than the usual 500–600 nm range typical of ring reduced phthalocyanine complexes.
- Full Text:
- Date Issued: 2008
Synthesis and photophysical properties of lead phthalocyanines
- Modibane, D.K., Nyokong, Tebello
- Authors: Modibane, D.K. , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268636 , vital:54216 , xlink:href="https://doi.org/10.1016/j.poly.2007.12.004"
- Description: This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and more than 10 μs in the rest of the solvents) were observed due to the presence of heavy atom.
- Full Text:
- Date Issued: 2008
- Authors: Modibane, D.K. , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268636 , vital:54216 , xlink:href="https://doi.org/10.1016/j.poly.2007.12.004"
- Description: This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and more than 10 μs in the rest of the solvents) were observed due to the presence of heavy atom.
- Full Text:
- Date Issued: 2008
The photophysical studies of a mixture of CdTe quantum dots and negatively charged zinc phthalocyanines
- Moeno, Sharon, Nyokong, Tebello
- Authors: Moeno, Sharon , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268663 , vital:54220 , xlink:href="https://doi.org/10.1016/j.poly.2008.03.007"
- Description: Fluorescence resonance energy transfer (FRET) studies were carried out with quantum dots capped with thioglycolic acid (TGA) and 2-mercaptoethanol (2-ME) and negatively charged phthalocyanines {Zn tetracarboxy (ZnTCPc), Zn octacarboxy (ZnOCPc) and Zn tetrasulfo (ZnTSPc) phthalocyinines} in a 0.1 NaOH:EtOH (50:50) solvent mixture. The best overlap between emission spectra of the donor (QDs) and the absorption spectra of the acceptor (ZnPc derivatives) was observed for TGA capped QDs, very little overlap was obtained for 2-ME QDs. ZnTSPc gave the highest FRET efficiency (0.3), with ZnOCPc and ZnTCPc giving a FRET efficiency of 0.2. The ΦT values of the MPcs generally decreased in the presence of the QD whereas the triplet lifetimes (τT) of the ZnPc derivatives were higher in the presence of QDs.
- Full Text:
- Date Issued: 2008
- Authors: Moeno, Sharon , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268663 , vital:54220 , xlink:href="https://doi.org/10.1016/j.poly.2008.03.007"
- Description: Fluorescence resonance energy transfer (FRET) studies were carried out with quantum dots capped with thioglycolic acid (TGA) and 2-mercaptoethanol (2-ME) and negatively charged phthalocyanines {Zn tetracarboxy (ZnTCPc), Zn octacarboxy (ZnOCPc) and Zn tetrasulfo (ZnTSPc) phthalocyinines} in a 0.1 NaOH:EtOH (50:50) solvent mixture. The best overlap between emission spectra of the donor (QDs) and the absorption spectra of the acceptor (ZnPc derivatives) was observed for TGA capped QDs, very little overlap was obtained for 2-ME QDs. ZnTSPc gave the highest FRET efficiency (0.3), with ZnOCPc and ZnTCPc giving a FRET efficiency of 0.2. The ΦT values of the MPcs generally decreased in the presence of the QD whereas the triplet lifetimes (τT) of the ZnPc derivatives were higher in the presence of QDs.
- Full Text:
- Date Issued: 2008
Spontaneous charge transfer between zinc tetramethyl-tetra-2, 3-pyridinoporphyrazine and CdTe and ZnS quantum dots
- Moeno, Sharon, Idowu, Mopelola, Nyokong, Tebello
- Authors: Moeno, Sharon , Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265997 , vital:53908 , xlink:href="https://doi.org/10.1016/j.ica.2008.02.048"
- Description: Zinc tetramethyl-tetra-2,3-pyridinoporphyrazine (ZnTmtppa(-2)) gets reduced to the ZnTmtppa(-3) species on interaction with CdTe QDs capped with 2-mercaptoethanol (2-ME) or thioglycolic acid (TGA) and ZnS QDs capped with 2-ME. The interaction occurs without photolysis. The fluorescence of the QDs is quenched by ZnTmtppa resulting in large quenching constants. Binding of ZnTmtppa to QDs occurs with two molecules of the former binding to the latter.
- Full Text:
- Date Issued: 2008
- Authors: Moeno, Sharon , Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265997 , vital:53908 , xlink:href="https://doi.org/10.1016/j.ica.2008.02.048"
- Description: Zinc tetramethyl-tetra-2,3-pyridinoporphyrazine (ZnTmtppa(-2)) gets reduced to the ZnTmtppa(-3) species on interaction with CdTe QDs capped with 2-mercaptoethanol (2-ME) or thioglycolic acid (TGA) and ZnS QDs capped with 2-ME. The interaction occurs without photolysis. The fluorescence of the QDs is quenched by ZnTmtppa resulting in large quenching constants. Binding of ZnTmtppa to QDs occurs with two molecules of the former binding to the latter.
- Full Text:
- Date Issued: 2008
Electrochemical and electrocatalytic properties of α-substituted manganese and titanium phthalocyanines
- Nombona, Nolwazi, Tau, Prudence, Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Tau, Prudence , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268587 , vital:54212 , xlink:href="https://doi.org/10.1016/j.electacta.2007.11.046"
- Description: This work reports on the synthesis of manganese and titanium phthalocyanine complexes that are tetra-substituted at four non-peripheral positions with amino ligands. The complexes are investigated for the first time for their electrochemical properties using cyclic voltammetry, rotating disc electrode voltammetry and spectroelectrochemistry. Electropolymerisation on a glassy carbon electrode was performed with ease and the modified electrodes were investigated for electrocatalysis of nitrite oxidation. Nitrite oxidation to nitrate is confirmed from the transfer of a total of two electrons.
- Full Text:
- Date Issued: 2008
- Authors: Nombona, Nolwazi , Tau, Prudence , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268587 , vital:54212 , xlink:href="https://doi.org/10.1016/j.electacta.2007.11.046"
- Description: This work reports on the synthesis of manganese and titanium phthalocyanine complexes that are tetra-substituted at four non-peripheral positions with amino ligands. The complexes are investigated for the first time for their electrochemical properties using cyclic voltammetry, rotating disc electrode voltammetry and spectroelectrochemistry. Electropolymerisation on a glassy carbon electrode was performed with ease and the modified electrodes were investigated for electrocatalysis of nitrite oxidation. Nitrite oxidation to nitrate is confirmed from the transfer of a total of two electrons.
- Full Text:
- Date Issued: 2008
A Bernsteinian analysis of the integration of natural resource management in the curriculum of a rural disadvantaged school
- Authors: Nsubuga, Yvonne
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386415 , vital:68139 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122771"
- Description: Knowledge integration is one of the key principles that underpin curriculum reform in post-apartheid South Africa. One form of teacher support that has been adopted in South Africa is to provide schools throughout the country with samples of pedagogic texts such as curriculum documents and examination exemplars to act as guidelines to teachers as they implement this new curriculum requirement. In the isolated and under-resourced rural schools of South Africa, these texts are the main form of curriculum guidance to teachers. Hence the knowledge integration principles and messages conveyed within these texts are of crucial importance. One contributory factor to the lack of information on knowledge integration at rural underresourced schools is the lack of simple and effective research tools by which to analyse and compare the extent of knowledge integration within pedagogic texts and classroom practices. This article reports on a Bernstein informed analysis that was carried out on three different Grade 10 Life Sciences pedagogic texts in order to assess the extent to which they integrate natural resource management (NRM). The study involved the construction of two indicator frameworks as the research tools with which the analysis was conducted. Results from the analysis showed that although the official Grade 10 Life Sciences pedagogic texts contained very high levels of NRM integration, this was not the case for the Grade 10 Life Sciences text that was produced at the school level. The study provides useful insight into curriculum recontextualisation at a rural under-resourced school through the lens of NRM integration within the Grade 10 Life Sciences pedagogic texts. Such insight has the potential to contribute to better curriculum design and implementation strategies to service schools. This will hopefully help to narrow the gap that currently exists between the official and enacted curricula.
- Full Text:
- Date Issued: 2008
- Authors: Nsubuga, Yvonne
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386415 , vital:68139 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122771"
- Description: Knowledge integration is one of the key principles that underpin curriculum reform in post-apartheid South Africa. One form of teacher support that has been adopted in South Africa is to provide schools throughout the country with samples of pedagogic texts such as curriculum documents and examination exemplars to act as guidelines to teachers as they implement this new curriculum requirement. In the isolated and under-resourced rural schools of South Africa, these texts are the main form of curriculum guidance to teachers. Hence the knowledge integration principles and messages conveyed within these texts are of crucial importance. One contributory factor to the lack of information on knowledge integration at rural underresourced schools is the lack of simple and effective research tools by which to analyse and compare the extent of knowledge integration within pedagogic texts and classroom practices. This article reports on a Bernstein informed analysis that was carried out on three different Grade 10 Life Sciences pedagogic texts in order to assess the extent to which they integrate natural resource management (NRM). The study involved the construction of two indicator frameworks as the research tools with which the analysis was conducted. Results from the analysis showed that although the official Grade 10 Life Sciences pedagogic texts contained very high levels of NRM integration, this was not the case for the Grade 10 Life Sciences text that was produced at the school level. The study provides useful insight into curriculum recontextualisation at a rural under-resourced school through the lens of NRM integration within the Grade 10 Life Sciences pedagogic texts. Such insight has the potential to contribute to better curriculum design and implementation strategies to service schools. This will hopefully help to narrow the gap that currently exists between the official and enacted curricula.
- Full Text:
- Date Issued: 2008
Electrocatalytic and photosensitizing behavior of metallophthalocyanine complexes
- Authors: Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265908 , vital:53899 , xlink:href="https://doi.org/10.1142/S1088424608000388"
- Description: Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co, Mn and Fe, whereas photosensitizing behavior is observed for diamagnetic metals such as Al, Zn and Si. In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
- Full Text:
- Date Issued: 2008
- Authors: Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265908 , vital:53899 , xlink:href="https://doi.org/10.1142/S1088424608000388"
- Description: Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co, Mn and Fe, whereas photosensitizing behavior is observed for diamagnetic metals such as Al, Zn and Si. In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
- Full Text:
- Date Issued: 2008
Synthesis, photophysical and photochemical studies on long chain zinc phthalocyanine derivatives
- Ogunsipe, Abimbola, Durmus, Mahmut, Atilla, Devrim, Gürek, Ayşe Gül, Ahsen, Vefa, Nyokong, Tebello
- Authors: Ogunsipe, Abimbola , Durmus, Mahmut , Atilla, Devrim , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266019 , vital:53910 , xlink:href="https://doi.org/10.1016/j.synthmet.2008.06.007"
- Description: The synthesis and characterization of 2,9,16,23-chloro-3,10,17,24-triethyleneoxysulphanylphthalocyaninato zinc(II) (CTESZnPc) is described. The photophysics and photochemistry of CTESZnPc and those of tetrakis(triethyleneoxysulphanyl)zinc phthalocyanine (TTESZnPc) and octakis(triethyleneoxysulphanyl)zinc phthalocyanine (OTESZnPc), are presented and compared with those of unsubstituted zinc phthalocyanine (ZnPc). The presence of triethyleneoxysulphanyl substituents on the ZnPc ring gave rise to higher values of singlet oxygen (ΦΔ) and photodegradation (ΦPd) quantum yields in DMF. However, TTESZnPc, OTESZnPc and CTESZnPc are less fluorescent than ZnPc, judging from their fluorescence quantum yield (ΦF) values. Fluorescence was lower in toluene than in DMF due to aggregation in the former solvent. Triplet quantum yield (ΦT) values were found to increase with the presence of substituents on the ZnPc ring, while triplet lifetimes (τT) were found to vary linearly with the logarithms of solvent viscosities. The fluorescences of the substituted ZnPc complexes were effectively quenched by benzoquinone (BQ), and the quenching data analyzed by the Stern–Volmer equation. The Stern–Volmer constants and the diffusion-controlled bimolecular rate constants were calculated.
- Full Text:
- Date Issued: 2008
- Authors: Ogunsipe, Abimbola , Durmus, Mahmut , Atilla, Devrim , Gürek, Ayşe Gül , Ahsen, Vefa , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/266019 , vital:53910 , xlink:href="https://doi.org/10.1016/j.synthmet.2008.06.007"
- Description: The synthesis and characterization of 2,9,16,23-chloro-3,10,17,24-triethyleneoxysulphanylphthalocyaninato zinc(II) (CTESZnPc) is described. The photophysics and photochemistry of CTESZnPc and those of tetrakis(triethyleneoxysulphanyl)zinc phthalocyanine (TTESZnPc) and octakis(triethyleneoxysulphanyl)zinc phthalocyanine (OTESZnPc), are presented and compared with those of unsubstituted zinc phthalocyanine (ZnPc). The presence of triethyleneoxysulphanyl substituents on the ZnPc ring gave rise to higher values of singlet oxygen (ΦΔ) and photodegradation (ΦPd) quantum yields in DMF. However, TTESZnPc, OTESZnPc and CTESZnPc are less fluorescent than ZnPc, judging from their fluorescence quantum yield (ΦF) values. Fluorescence was lower in toluene than in DMF due to aggregation in the former solvent. Triplet quantum yield (ΦT) values were found to increase with the presence of substituents on the ZnPc ring, while triplet lifetimes (τT) were found to vary linearly with the logarithms of solvent viscosities. The fluorescences of the substituted ZnPc complexes were effectively quenched by benzoquinone (BQ), and the quenching data analyzed by the Stern–Volmer equation. The Stern–Volmer constants and the diffusion-controlled bimolecular rate constants were calculated.
- Full Text:
- Date Issued: 2008
Eco-Schools and the quality of education in South Africa: Realising the potential
- Authors: Rosenberg, Eureta
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386487 , vital:68146 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122759"
- Description: Eco-Schools South Africa is increasingly being used by external partners as a framework for supporting environmental education in schools. This paper shares the findings of a recent evaluation of the programme in relation to the quality of education in South African schools. Do Eco-Schools activities help to improve the conditions of teaching and learning? Or do they take teachers and students away from their core focus? Evaluation of learner and teacher work in Eco-Schools found signs of the quality problems that currently plague the schools system, and there is evidence that the programme can add to the complexity to which many teachers struggle to respond. The evaluation also found, however, that the programme has significant potential to improve conditions for teaching and learning. The paper is an opportunity to reflect on how environmental education support for schools, in general, and Eco-Schools South Africa, in particular, can detract from and strengthen teaching and learning.
- Full Text:
- Date Issued: 2008
- Authors: Rosenberg, Eureta
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386487 , vital:68146 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122759"
- Description: Eco-Schools South Africa is increasingly being used by external partners as a framework for supporting environmental education in schools. This paper shares the findings of a recent evaluation of the programme in relation to the quality of education in South African schools. Do Eco-Schools activities help to improve the conditions of teaching and learning? Or do they take teachers and students away from their core focus? Evaluation of learner and teacher work in Eco-Schools found signs of the quality problems that currently plague the schools system, and there is evidence that the programme can add to the complexity to which many teachers struggle to respond. The evaluation also found, however, that the programme has significant potential to improve conditions for teaching and learning. The paper is an opportunity to reflect on how environmental education support for schools, in general, and Eco-Schools South Africa, in particular, can detract from and strengthen teaching and learning.
- Full Text:
- Date Issued: 2008
Eco-Schools and the quality of education in South Africa: Realising the potential
- Authors: Rosenberg, Eureta
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370511 , vital:66349 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122759"
- Description: Eco-Schools South Africa is increasingly being used by external partners as a framework for supporting environmental education in schools. This paper shares the findings of a recent evaluation of the programme in relation to the quality of education in South African schools. Do Eco-Schools activities help to improve the conditions of teaching and learning? Or do they take teachers and students away from their core focus? Evaluation of learner and teacher work in Eco-Schools found signs of the quality problems that currently plague the schools system, and there is evidence that the programme can add to the complexity to which many teachers struggle to respond. The evaluation also found, however, that the programme has significant potential to improve conditions for teaching and learning. The paper is an opportunity to reflect on how environmental education support for schools, in general, and Eco-Schools South Africa, in particular, can detract from and strengthen teaching and learning.
- Full Text:
- Date Issued: 2008
- Authors: Rosenberg, Eureta
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370511 , vital:66349 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122759"
- Description: Eco-Schools South Africa is increasingly being used by external partners as a framework for supporting environmental education in schools. This paper shares the findings of a recent evaluation of the programme in relation to the quality of education in South African schools. Do Eco-Schools activities help to improve the conditions of teaching and learning? Or do they take teachers and students away from their core focus? Evaluation of learner and teacher work in Eco-Schools found signs of the quality problems that currently plague the schools system, and there is evidence that the programme can add to the complexity to which many teachers struggle to respond. The evaluation also found, however, that the programme has significant potential to improve conditions for teaching and learning. The paper is an opportunity to reflect on how environmental education support for schools, in general, and Eco-Schools South Africa, in particular, can detract from and strengthen teaching and learning.
- Full Text:
- Date Issued: 2008
Electro-catalyzed oxidation of reduced glutathione and 2-mercaptoethanol by cobalt phthalocyanine-containing screen printed graphite electrodes
- Sehlotho, Nthapo, Griveau, Sophie, Ruillé, Nadine, Boujtita, Mohammed, Nyokong, Tebello, Bedioui, Fethi
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Ruillé, Nadine , Boujtita, Mohammed , Nyokong, Tebello , Bedioui, Fethi
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265935 , vital:53902 , xlink:href="https://doi.org/10.1016/j.msec.2007.10.054"
- Description: Electro-catalytic behavior of screen printed graphite electrodes modified with cobalt phthalocyanine (CoPc) towards the oxidation of reduced glutathione (GSH) and 2-mercaptoethanol (2-ME) is reported. We find, by using cyclic voltammetry, that the oxidation of 2-ME occurs at 0.2 V vs Ag/AgCl and − 0.3 vs Ag/AgCl V at pH = 7 and pH = 13, respectively and that of GSH occurs at 0.4 V vs Ag/AgCl and 0.0 V vs Ag/AgCl at pH = 7 and 13, respectively. The electro-catalytic activity depends on the method of electrode modification and the amount of catalyst incorporated in the ink used to fabricate the SPCEs. The highest activity was obtained with electrodes prepared with 2.5% (w:w) of CoPc.
- Full Text:
- Date Issued: 2008
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Ruillé, Nadine , Boujtita, Mohammed , Nyokong, Tebello , Bedioui, Fethi
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265935 , vital:53902 , xlink:href="https://doi.org/10.1016/j.msec.2007.10.054"
- Description: Electro-catalytic behavior of screen printed graphite electrodes modified with cobalt phthalocyanine (CoPc) towards the oxidation of reduced glutathione (GSH) and 2-mercaptoethanol (2-ME) is reported. We find, by using cyclic voltammetry, that the oxidation of 2-ME occurs at 0.2 V vs Ag/AgCl and − 0.3 vs Ag/AgCl V at pH = 7 and pH = 13, respectively and that of GSH occurs at 0.4 V vs Ag/AgCl and 0.0 V vs Ag/AgCl at pH = 7 and 13, respectively. The electro-catalytic activity depends on the method of electrode modification and the amount of catalyst incorporated in the ink used to fabricate the SPCEs. The highest activity was obtained with electrodes prepared with 2.5% (w:w) of CoPc.
- Full Text:
- Date Issued: 2008
Social and ecological trade offs in combating land degradation: The case of invasion by a woody shrub (Euryops floribundus) at Macubeni, South Africa
- Shackleton, Charlie M, Gambiza, James
- Authors: Shackleton, Charlie M , Gambiza, James
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181235 , vital:43711 , xlink:href="https://doi.org/10.1002/ldr.849"
- Description: Woody plant invasions, either of alien or indigenous species, are deemed to result in loss of ecosystem goods and services in many areas throughout the world, resulting in significant degradation and economic costs. Invasion of Euryops floribundus, a species indigenous to South Africa, is perceived to have reduced the grazing available for domestic livestock. Consequently, a programme of manual eradication has been implemented to improve the grazing resource and provide jobs for poverty alleviation. However, there is potential for a conflict of interest as our study shows that almost all households rely on Euryops for fuel and at times fencing material, whereas only a minority of households own livestock. Moreover, comparison of invaded and non-invaded sites indicated that the invaded sites harbour greater plant species richness and higher grass culm density per unit area of grass cover, as well as higher forb and litter cover. While invaded sites had lower grass cover, overall plant cover was no different between invaded and non-invaded sites. Multivariate analysis indicated no obvious differentiation in community composition between invaded and non-invaded areas, suggesting stronger drivers of community composition other than Euryops invasion presumed to be facilitated by the effects of high livestock densities. Overall, our study suggests that the clearing operation may well benefit from a better understanding of the social needs, perceptions of degradation by the various stakeholders and ecological dynamics of the area, especially local reliance on the resources, and the dynamics of the invasion, particularly its extent, rate of spread and susceptibility for re-invasion in the cleared areas.
- Full Text:
- Date Issued: 2008
- Authors: Shackleton, Charlie M , Gambiza, James
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181235 , vital:43711 , xlink:href="https://doi.org/10.1002/ldr.849"
- Description: Woody plant invasions, either of alien or indigenous species, are deemed to result in loss of ecosystem goods and services in many areas throughout the world, resulting in significant degradation and economic costs. Invasion of Euryops floribundus, a species indigenous to South Africa, is perceived to have reduced the grazing available for domestic livestock. Consequently, a programme of manual eradication has been implemented to improve the grazing resource and provide jobs for poverty alleviation. However, there is potential for a conflict of interest as our study shows that almost all households rely on Euryops for fuel and at times fencing material, whereas only a minority of households own livestock. Moreover, comparison of invaded and non-invaded sites indicated that the invaded sites harbour greater plant species richness and higher grass culm density per unit area of grass cover, as well as higher forb and litter cover. While invaded sites had lower grass cover, overall plant cover was no different between invaded and non-invaded sites. Multivariate analysis indicated no obvious differentiation in community composition between invaded and non-invaded areas, suggesting stronger drivers of community composition other than Euryops invasion presumed to be facilitated by the effects of high livestock densities. Overall, our study suggests that the clearing operation may well benefit from a better understanding of the social needs, perceptions of degradation by the various stakeholders and ecological dynamics of the area, especially local reliance on the resources, and the dynamics of the invasion, particularly its extent, rate of spread and susceptibility for re-invasion in the cleared areas.
- Full Text:
- Date Issued: 2008