Synthesis and solvent effects on the photophysicochemical properties of novel cadmium phenoxy phthalocyanines
- Chidawanyika, Wadzanai J U, Antunes, Edith M, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai J U , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268649 , vital:54217 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.09.020"
- Description: The syntheses of novel cadmium phenoxy complexes; tetrakis{1,(4)-tert-butylphenoxyphthalocyaninato}cadmium(II) (5a), tetrakis{1,(4)-phenoxyphthalocyaninato}cadmium(II) (5b), tetrakis{2,(3)-tert-butylphenoxyphthalocyaninato}cadmium(II) (6a) and tetrakis{2,(3)-phenoxyphthalocyaninato}cadmium(II) (6b) are presented herein. The spectroscopic and photophysicochemical properties have also been carried out and discussed together with the influence of various organic solvents on these properties. Spectroscopic properties, i.e. ground state electronic absorption and fluorescence spectra have been found to vary as a function of substituent position on the phthalocyanine macrocycle, i.e. α-substitution versus β-substitution. The photophysical parameters are reported as well as the photodegradation and singlet oxygen quantum yields, where the complexes were found to exhibit good photostability with the production of appreciable amounts of singlet oxygen.
- Full Text:
- Authors: Chidawanyika, Wadzanai J U , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268649 , vital:54217 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.09.020"
- Description: The syntheses of novel cadmium phenoxy complexes; tetrakis{1,(4)-tert-butylphenoxyphthalocyaninato}cadmium(II) (5a), tetrakis{1,(4)-phenoxyphthalocyaninato}cadmium(II) (5b), tetrakis{2,(3)-tert-butylphenoxyphthalocyaninato}cadmium(II) (6a) and tetrakis{2,(3)-phenoxyphthalocyaninato}cadmium(II) (6b) are presented herein. The spectroscopic and photophysicochemical properties have also been carried out and discussed together with the influence of various organic solvents on these properties. Spectroscopic properties, i.e. ground state electronic absorption and fluorescence spectra have been found to vary as a function of substituent position on the phthalocyanine macrocycle, i.e. α-substitution versus β-substitution. The photophysical parameters are reported as well as the photodegradation and singlet oxygen quantum yields, where the complexes were found to exhibit good photostability with the production of appreciable amounts of singlet oxygen.
- Full Text:
Synthesis, electrochemical characterization of tetra-and octa-substituted dodecyl-mercapto tin phthalocyanines in solution and as self-assembled monolayers
- Khene, Samson M, Geraldo, Daniela A, Togo, Chamunorwa A, Limson, Janice L, Nyokong, Tebello
- Authors: Khene, Samson M , Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264541 , vital:53743 , xlink:href="https://doi.org/10.1016/j.electacta.2008.08.018"
- Description: Non-peripherally (α) tetra- (9) and octa-(7) substituted dodecyl-mercapto tin(IV) phthalocyanines were synthesized and their electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for 7 and 9, the former shows two ring oxidations, while the latter shows only one ring-based oxidation. The adsorption kinetics of (7) and (9) on gold electrode were investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy (ΔGads) of the SAMs were evaluated based on the Frumkin isotherm.
- Full Text:
- Authors: Khene, Samson M , Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264541 , vital:53743 , xlink:href="https://doi.org/10.1016/j.electacta.2008.08.018"
- Description: Non-peripherally (α) tetra- (9) and octa-(7) substituted dodecyl-mercapto tin(IV) phthalocyanines were synthesized and their electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for 7 and 9, the former shows two ring oxidations, while the latter shows only one ring-based oxidation. The adsorption kinetics of (7) and (9) on gold electrode were investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy (ΔGads) of the SAMs were evaluated based on the Frumkin isotherm.
- Full Text:
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:
- 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.
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The Cultural Use of the Wild Olive Tree by the amaXhosa People in the Eastern Cape Province of South Africa:
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141314 , vital:37961 , DOI: 10.1558/jsrnc.v2i3.292
- Description: The cultural meanings of harvested plants have for the most part been ignored in academic research on non-timber forest products (NTFPs) in southern Africa. Historically scientists have tended to ignore the complex relationships between nature and culture. Given the country's unique political and economic past and the current search for sustainable use of natural resources, a focus on the convergence of natural science and cultural diversity is important at this time. Empirical data on cultural practices is being collected in order to develop fresh and relevant insights into the complex relationships between culture and bítKÜversity. The purpose of this paper is to demonstrate that the concept of culture needs to be brought into our understanding of the role of NTFPs. We dtxrument the use and value of a specific tree, Olea europaea L. subsp. africana (Mill.) P,S. Green, called Umiicjuma in the Xhosa language, for cultural purposes, by both rural and urban households.
- Full Text:
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141314 , vital:37961 , DOI: 10.1558/jsrnc.v2i3.292
- Description: The cultural meanings of harvested plants have for the most part been ignored in academic research on non-timber forest products (NTFPs) in southern Africa. Historically scientists have tended to ignore the complex relationships between nature and culture. Given the country's unique political and economic past and the current search for sustainable use of natural resources, a focus on the convergence of natural science and cultural diversity is important at this time. Empirical data on cultural practices is being collected in order to develop fresh and relevant insights into the complex relationships between culture and bítKÜversity. The purpose of this paper is to demonstrate that the concept of culture needs to be brought into our understanding of the role of NTFPs. We dtxrument the use and value of a specific tree, Olea europaea L. subsp. africana (Mill.) P,S. Green, called Umiicjuma in the Xhosa language, for cultural purposes, by both rural and urban households.
- Full Text:
The development of ICT networks for South African schools: Two pilot studies in disadvantaged areas
- Siebörger, Ingrid, Terzoli, Alfredo, Hodgkinson-Williams, Cheryl
- Authors: Siebörger, Ingrid , Terzoli, Alfredo , Hodgkinson-Williams, Cheryl
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431018 , vital:72737 , https://doi.org/10.1007/978-0-387-09729-9_25
- Description: Information and Communication Technologies (ICTs) are increasingly considered valuable tools in educa-tion, promoting the development of higher cognitive processes and allowing teachers and learners access to a plethora of information. This paper reports on two pilot studies conducted in South Africa in proto-typical previously disadvantaged schools and their surrounding communities. Each pilot study deployed a local loop network within impoverished communi-ties, connecting schools to one another and central services such as email and voice communications. The benefits of these networks were that teachers, learners and the local community had access to in-formation, and communication and collaboration channels, providing potential test beds for investigat-ing the use of computers as mind tools.
- Full Text:
- Authors: Siebörger, Ingrid , Terzoli, Alfredo , Hodgkinson-Williams, Cheryl
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431018 , vital:72737 , https://doi.org/10.1007/978-0-387-09729-9_25
- Description: Information and Communication Technologies (ICTs) are increasingly considered valuable tools in educa-tion, promoting the development of higher cognitive processes and allowing teachers and learners access to a plethora of information. This paper reports on two pilot studies conducted in South Africa in proto-typical previously disadvantaged schools and their surrounding communities. Each pilot study deployed a local loop network within impoverished communi-ties, connecting schools to one another and central services such as email and voice communications. The benefits of these networks were that teachers, learners and the local community had access to in-formation, and communication and collaboration channels, providing potential test beds for investigat-ing the use of computers as mind tools.
- Full Text:
The Internet in rural communities: unrestricted and contextualized
- Thinyane, Mamello, Dalvit, Lorenzo, Terzoli, Alfredo, Clayton, Peter G
- Authors: Thinyane, Mamello , Dalvit, Lorenzo , Terzoli, Alfredo , Clayton, Peter G
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431344 , vital:72766 , https://www.researchgate.net/profile/Alfredo-Ter-zoli/publication/262259378_The_Internet_in_rural_communities_unrestricted_and_contextualized/links/6597ec140bb2c7472b35fcac/The-Internet-in-rural-communities-unrestricted-and-contextualized.pdf
- Description: The benefits of the Internet are still not available to many marginalized communities because of lack of connectivity, costs of infrastructure and scarcity of skills. Many ICTforDevelopment (ICT4D) projects offer piecemeal interventions relying either on restricted (and often decontex-tualised) access to the Internet or on isolated Local Area Networks (LANs). In this paper we argue that marginalized rural communities should have unrestricted access to the Internet in order to exploit its full potential. We also believe that the Internet could be contextualized through an optional adaptation layer which would facilitate access. We discuss an ICT4D project which was shaped from the very beginning according to these principles. It involves the deployment of an eCom-merce platform (soon to be integrated with eHealth, eLearning and eGovernment capabilities) in a rural community in South Africa. We re-port on how the various components of this intervention fit into the model, and the benefits for the community.
- Full Text:
- Authors: Thinyane, Mamello , Dalvit, Lorenzo , Terzoli, Alfredo , Clayton, Peter G
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431344 , vital:72766 , https://www.researchgate.net/profile/Alfredo-Ter-zoli/publication/262259378_The_Internet_in_rural_communities_unrestricted_and_contextualized/links/6597ec140bb2c7472b35fcac/The-Internet-in-rural-communities-unrestricted-and-contextualized.pdf
- Description: The benefits of the Internet are still not available to many marginalized communities because of lack of connectivity, costs of infrastructure and scarcity of skills. Many ICTforDevelopment (ICT4D) projects offer piecemeal interventions relying either on restricted (and often decontex-tualised) access to the Internet or on isolated Local Area Networks (LANs). In this paper we argue that marginalized rural communities should have unrestricted access to the Internet in order to exploit its full potential. We also believe that the Internet could be contextualized through an optional adaptation layer which would facilitate access. We discuss an ICT4D project which was shaped from the very beginning according to these principles. It involves the deployment of an eCom-merce platform (soon to be integrated with eHealth, eLearning and eGovernment capabilities) in a rural community in South Africa. We re-port on how the various components of this intervention fit into the model, and the benefits for the community.
- Full Text:
The localisation into isiXhosa of the iLanga telephone system
- Dalvit, Lorenzo, Tsietsi, Mosiuoa, Terzoli, Alfredo, Maseko, Pamela, Sam, Msindisi, Mapi, Thandeka
- Authors: Dalvit, Lorenzo , Tsietsi, Mosiuoa , Terzoli, Alfredo , Maseko, Pamela , Sam, Msindisi , Mapi, Thandeka
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431358 , vital:72767 , https://nru.uncst.go.ug/bitstream/handle/123456789/6552/Information%20Communica-tion%20Technologies%20%20page%20410.pdf?sequence=1isAllowed=y#page=256
- Description: In this paper we describe the localisation of iLanga, a VoIP PBX sys-tem, into isiXhosa. In South Africa, for social and political reasons, mak-ing systems available in the African languages is becoming more and more important. On the one hand, it gives access to the use of technol-ogy to people who are not fluent in English. On the other hand, it has a strong symbolic value. Although a variety of software is already availa-ble in a number of African languages, localisation in such language is still in its early stage. The process presented interesting challenges both from the technical and the linguistic point of view.
- Full Text:
- Authors: Dalvit, Lorenzo , Tsietsi, Mosiuoa , Terzoli, Alfredo , Maseko, Pamela , Sam, Msindisi , Mapi, Thandeka
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431358 , vital:72767 , https://nru.uncst.go.ug/bitstream/handle/123456789/6552/Information%20Communica-tion%20Technologies%20%20page%20410.pdf?sequence=1isAllowed=y#page=256
- Description: In this paper we describe the localisation of iLanga, a VoIP PBX sys-tem, into isiXhosa. In South Africa, for social and political reasons, mak-ing systems available in the African languages is becoming more and more important. On the one hand, it gives access to the use of technol-ogy to people who are not fluent in English. On the other hand, it has a strong symbolic value. Although a variety of software is already availa-ble in a number of African languages, localisation in such language is still in its early stage. The process presented interesting challenges both from the technical and the linguistic point of view.
- Full Text:
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:
- 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:
The Postcolonial heart of African philosophy
- Authors: Tabensky, Pedro
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305762 , vital:58610 , xlink:href="https://hdl.handle.net/10520/EJC96056"
- Description: This piece is one of among a handful that seek in the first instance to reveal the origin of African philosophy as an academic discipline, the source of its unity and distinctiveness. The discipline of African philosophy originates in tragedy, out of pain, confusion and rage stemming from colonial destruction; destruction that is responsible for what Fanon calls the ‘negro neurosis’ caused by what Biko would describe as the unbearable fusion of colonised and coloniser. I argue that the birth of African philosophy as an academic discipline is largely responsible for its character and, crucially, for its distinctive creative possibilities.
- Full Text:
- Authors: Tabensky, Pedro
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305762 , vital:58610 , xlink:href="https://hdl.handle.net/10520/EJC96056"
- Description: This piece is one of among a handful that seek in the first instance to reveal the origin of African philosophy as an academic discipline, the source of its unity and distinctiveness. The discipline of African philosophy originates in tragedy, out of pain, confusion and rage stemming from colonial destruction; destruction that is responsible for what Fanon calls the ‘negro neurosis’ caused by what Biko would describe as the unbearable fusion of colonised and coloniser. I argue that the birth of African philosophy as an academic discipline is largely responsible for its character and, crucially, for its distinctive creative possibilities.
- Full Text:
The relationship between emergence of the shortest path and information value using ant-like agents
- Chibaya, Colin, Bangay, Shaun D
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433318 , vital:72961 , https://doi.org/10.1145/1456659.1456663
- Description: Ant-like agents forage between two points. These agents' probabilistic movements are based on the use of two pheromones; one marking trails towards the goal and another marking trails back to the starting point. Path selection decisions are influenced by the relative levels of attractive and repulsive pheromone in each agent's local environment. Our work in [5] evaluates three pheromone perception strategies, investigating path formation speed, quality, directionality, robustness and adaptability under different parameter settings(degree of randomness, pheromone evaporation rate and pheromone diffusion rate).
- Full Text:
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433318 , vital:72961 , https://doi.org/10.1145/1456659.1456663
- Description: Ant-like agents forage between two points. These agents' probabilistic movements are based on the use of two pheromones; one marking trails towards the goal and another marking trails back to the starting point. Path selection decisions are influenced by the relative levels of attractive and repulsive pheromone in each agent's local environment. Our work in [5] evaluates three pheromone perception strategies, investigating path formation speed, quality, directionality, robustness and adaptability under different parameter settings(degree of randomness, pheromone evaporation rate and pheromone diffusion rate).
- Full Text:
The role of indigenous knowledge in computer education in Africa
- Dalvit, Lorenzo, Murray, Sarah, Terzoli, Alfredo
- Authors: Dalvit, Lorenzo , Murray, Sarah , Terzoli, Alfredo
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431033 , vital:72739 , https://doi.org/10.1007/978-0-387-09729-9_43
- Description: The integration of indigenous knowledge/languages in formal education is a contentious issue in post-colonial Africa. For historical and econom-ic reasons, these are devalued in the formal education system. We ar-gue that appropriate use of indigenous knowledge/languages can em-power African students academically even in typically “Western” disci-plines, such as Computer Science. We discuss the potential role of in-digenous languages/knowledge in ICT education and then describe an intervention, supporting students from marginalised communities, at a South African University.
- Full Text:
- Authors: Dalvit, Lorenzo , Murray, Sarah , Terzoli, Alfredo
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431033 , vital:72739 , https://doi.org/10.1007/978-0-387-09729-9_43
- Description: The integration of indigenous knowledge/languages in formal education is a contentious issue in post-colonial Africa. For historical and econom-ic reasons, these are devalued in the formal education system. We ar-gue that appropriate use of indigenous knowledge/languages can em-power African students academically even in typically “Western” disci-plines, such as Computer Science. We discuss the potential role of in-digenous languages/knowledge in ICT education and then describe an intervention, supporting students from marginalised communities, at a South African University.
- Full Text:
The role of the privileged in responding to poverty: perspectives emerging from the post-development debate
- Authors: Matthews, Sally
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142476 , vital:38083 , DOI: 10.1080/01436590802201022
- Description: The debate between post-development theorists and their critics has raised several important questions, one of them being the question of how relatively privileged people may respond meaningfully to poverty while not perpetuating the flaws of past development practice. In this article I build upon the ideas of several contributors to the post-development debate in order to suggest three ways in which we who are relatively privileged may play a role in struggles against poverty. I argue that we can work to rethink the concepts informing development practice; that we may find ways to give our support to popular initiatives, and that there are aspects of our own societies which we may change in solidarity with the struggles of distant others.
- Full Text:
- Authors: Matthews, Sally
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142476 , vital:38083 , DOI: 10.1080/01436590802201022
- Description: The debate between post-development theorists and their critics has raised several important questions, one of them being the question of how relatively privileged people may respond meaningfully to poverty while not perpetuating the flaws of past development practice. In this article I build upon the ideas of several contributors to the post-development debate in order to suggest three ways in which we who are relatively privileged may play a role in struggles against poverty. I argue that we can work to rethink the concepts informing development practice; that we may find ways to give our support to popular initiatives, and that there are aspects of our own societies which we may change in solidarity with the struggles of distant others.
- Full Text:
The Sacred Door and other Stories: Cameroon Folktales of the Beba (Makuchi)
- Authors: Kaschula, Russell H
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175177 , vital:42550 , https://doi.org/10.17159/2309-9070/tvl.v.45i2.4743
- Description: In The Sacred Door and Other Stories: Cameroon Folktales of the Beba, Makuchi has collected thirty-three folktales of the Beba people. These stories are presented in English only. The book contains a foreword by well-known oral literature scholar, Isidore Okpewho and a preface by the author. In the foreword, Okpewho states that:“Tales like these need to be retold again and again, because the lessons they yield belong not merely to a long-forgotten historical or so-called primitive past but very much to the present times in which we live”(xi). The book therefore represents a sense of continuity between past and present. Although the tales may no longer be told in the same way that they were many years ago, the messages contained in the tales remain as relevant today as they did in the past.
- Full Text:
- Authors: Kaschula, Russell H
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175177 , vital:42550 , https://doi.org/10.17159/2309-9070/tvl.v.45i2.4743
- Description: In The Sacred Door and Other Stories: Cameroon Folktales of the Beba, Makuchi has collected thirty-three folktales of the Beba people. These stories are presented in English only. The book contains a foreword by well-known oral literature scholar, Isidore Okpewho and a preface by the author. In the foreword, Okpewho states that:“Tales like these need to be retold again and again, because the lessons they yield belong not merely to a long-forgotten historical or so-called primitive past but very much to the present times in which we live”(xi). The book therefore represents a sense of continuity between past and present. Although the tales may no longer be told in the same way that they were many years ago, the messages contained in the tales remain as relevant today as they did in the past.
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Towards a taxonomy of network scanning techniques
- Barnett, Richard J, Irwin, Barry V W
- Authors: Barnett, Richard J , Irwin, Barry V W
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430310 , vital:72682 , https://doi.org/10.1145/1456659.1456660
- Description: Network scanning is a common reconnaissance activity in network in-trusion. Despite this, it's classification remains vague and detection sys-tems in current Network Intrusion Detection Systems are incapable of detecting many forms of scanning traffic. This paper presents a classi-fication of network scanning and illustrates how complex and varied this activity is. The presented classification extends previous, well known, definitions of scanning traffic in a manner which reflects this complexity.
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- Authors: Barnett, Richard J , Irwin, Barry V W
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430310 , vital:72682 , https://doi.org/10.1145/1456659.1456660
- Description: Network scanning is a common reconnaissance activity in network in-trusion. Despite this, it's classification remains vague and detection sys-tems in current Network Intrusion Detection Systems are incapable of detecting many forms of scanning traffic. This paper presents a classi-fication of network scanning and illustrates how complex and varied this activity is. The presented classification extends previous, well known, definitions of scanning traffic in a manner which reflects this complexity.
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Tracing and erasure in Kathryn Smith's Psychogeographies: the washing away of wrongs
- Authors: de Jager, Maureen
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147413 , vital:38634 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC31057
- Description: Kathryn Smith's Psychogeographies: The Washing Away of Wrongs is a series of twelve prints comprising photographs and handwritten text, wherein she records her 'pilgrimage' to the former homes of British serial killer Dennis Nilsen. As such, it utilises photographic and autographic traces to 'track' the elusive traces left by Nilsen. Given the lapse of two decades between Nilsen's arrest and Smith's visit, the traces of Nilsen's 'wrongs' seem all but erased by the banal façade of suburban living which has continued on, regardless. In taking this as a starting point, the following article considers the motif of absence that characterises Smith's work as intrinsic to traces per se.
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- Authors: de Jager, Maureen
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147413 , vital:38634 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC31057
- Description: Kathryn Smith's Psychogeographies: The Washing Away of Wrongs is a series of twelve prints comprising photographs and handwritten text, wherein she records her 'pilgrimage' to the former homes of British serial killer Dennis Nilsen. As such, it utilises photographic and autographic traces to 'track' the elusive traces left by Nilsen. Given the lapse of two decades between Nilsen's arrest and Smith's visit, the traces of Nilsen's 'wrongs' seem all but erased by the banal façade of suburban living which has continued on, regardless. In taking this as a starting point, the following article considers the motif of absence that characterises Smith's work as intrinsic to traces per se.
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Transitions towards a knowledge society: Aspectual pre-evaluation of a culture-sensitive implementation framework
- Thinyane, Mamello, Terzoli, Alfredo, Clayton, Peter G
- Authors: Thinyane, Mamello , Terzoli, Alfredo , Clayton, Peter G
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431054 , vital:72741 , https://doi.org/10.1007/978-0-387-09729-9_41
- Description: Information and Communication Technology (ICT) is aiding the transi-tion of society into information society and ultimately knowledge society. Embedded within ICT are the cultural and philosophical undercurrents of the society in which the ICT solutions are developed, currently pre-dominantly the Western culture. The proliferation of ICT is therefore in-advertedly leading to more Westernization of the world. It is important, therefore, that ICT solutions are culture sensitive and flexible enough to be situated within different cultures. To that end, we utilize Herman Dooyeweerd’s Theory of Modal Aspects to analyze a framework we has developed for implementation of locally situated knowledge based systems, to determine its efficacy in addressing the different modal as-pects, which make up the total experience and cultural expressiveness of societies.
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- Authors: Thinyane, Mamello , Terzoli, Alfredo , Clayton, Peter G
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431054 , vital:72741 , https://doi.org/10.1007/978-0-387-09729-9_41
- Description: Information and Communication Technology (ICT) is aiding the transi-tion of society into information society and ultimately knowledge society. Embedded within ICT are the cultural and philosophical undercurrents of the society in which the ICT solutions are developed, currently pre-dominantly the Western culture. The proliferation of ICT is therefore in-advertedly leading to more Westernization of the world. It is important, therefore, that ICT solutions are culture sensitive and flexible enough to be situated within different cultures. To that end, we utilize Herman Dooyeweerd’s Theory of Modal Aspects to analyze a framework we has developed for implementation of locally situated knowledge based systems, to determine its efficacy in addressing the different modal as-pects, which make up the total experience and cultural expressiveness of societies.
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Tuning the redox properties of Co-N4 macrocyclic complexes for the catalytic electrooxidation of glucose
- Villagra, Evelyn, Bedioui, Fethi, Nyokong, Tebello, Canales, J Carlos, Sancy, Mamie, Páez, Maritza A, Costamagna, Juan, Zagal, Jose H
- Authors: Villagra, Evelyn , Bedioui, Fethi , Nyokong, Tebello , Canales, J Carlos , Sancy, Mamie , Páez, Maritza A , Costamagna, Juan , Zagal, Jose H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268675 , vital:54221 , xlink:href="https://doi.org/10.1016/j.electacta.2008.02.006"
- Description: Graphite electrodes modified with four different cobalt N4 macrocyclics, namely Co tetrapentapyridinophthalocyanine, (CoTPenPyrPc), Co tetrapyridinoporphyrazine (CoTPyPz), Co octa(hydroxyethylthio)phthalocyanine (CoOEHTPc) and Co tetranitrophthalocyanine (CoTNPc) exhibit catalytic activity for the oxidation of glucose in alkaline media. The purpose of this work is to establish correlations between the catalytic activity of these complexes and their redox potential. The activity of the different modified electrodes was tested by linear voltammetry under hydrodynamic conditions using the rotating disk technique. Tafel plots constructed from mass-transport corrected currents give slopes ranging from 0.080 to 0.160 V/decade for the different catalysts which suggests that a first one-electron step is rate controlling with the symmetry of the energy barrier depending on the nature of the ligand of the Co complex. A plot of log I versus the Co(II)/(I) formal potential gives a volcano curve that also includes catalysts studied previously. This illustrates the concept that the formal potential of the catalyst needs to be tuned to a certain value for achieving maximum activity. A theoretical interpretation of these results is given in terms of Langmuir isotherms for the adsorption of glucose on the Co sites of the surface-confined metal complexes.
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- Authors: Villagra, Evelyn , Bedioui, Fethi , Nyokong, Tebello , Canales, J Carlos , Sancy, Mamie , Páez, Maritza A , Costamagna, Juan , Zagal, Jose H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268675 , vital:54221 , xlink:href="https://doi.org/10.1016/j.electacta.2008.02.006"
- Description: Graphite electrodes modified with four different cobalt N4 macrocyclics, namely Co tetrapentapyridinophthalocyanine, (CoTPenPyrPc), Co tetrapyridinoporphyrazine (CoTPyPz), Co octa(hydroxyethylthio)phthalocyanine (CoOEHTPc) and Co tetranitrophthalocyanine (CoTNPc) exhibit catalytic activity for the oxidation of glucose in alkaline media. The purpose of this work is to establish correlations between the catalytic activity of these complexes and their redox potential. The activity of the different modified electrodes was tested by linear voltammetry under hydrodynamic conditions using the rotating disk technique. Tafel plots constructed from mass-transport corrected currents give slopes ranging from 0.080 to 0.160 V/decade for the different catalysts which suggests that a first one-electron step is rate controlling with the symmetry of the energy barrier depending on the nature of the ligand of the Co complex. A plot of log I versus the Co(II)/(I) formal potential gives a volcano curve that also includes catalysts studied previously. This illustrates the concept that the formal potential of the catalyst needs to be tuned to a certain value for achieving maximum activity. A theoretical interpretation of these results is given in terms of Langmuir isotherms for the adsorption of glucose on the Co sites of the surface-confined metal complexes.
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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.
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- 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.
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Using inetvis to evaluate snort and bro scan detection on a network telescope
- Irwin, Barry V W, van Riel, J P
- Authors: Irwin, Barry V W , van Riel, J P
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429981 , vital:72656 , https://doi.org/10.1007/978-3-540-78243-8_17
- Description: This paper presents an investigative analysis of net-work scans and scan detection algorithms. Visualisa-tion is employed to review network telescope traffic and identify incidents of scan activity. Some of the identified phenomena appear to be novel forms of host discovery. Scan detection algorithms used by the Snort and Bro intrusion detection systems are cri-tiqued by comparing the visualised scans with alert output. Where human assessment disagrees with the alert output, explanations are sought by analysing the detection algorithms. The Snort and Bro algorithms are based on counting unique connection attempts to destination addresses and ports. For Snort, notable false positive and false negative cases result due to a grossly oversimplified method of counting unique destination addresses and ports.
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- Authors: Irwin, Barry V W , van Riel, J P
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429981 , vital:72656 , https://doi.org/10.1007/978-3-540-78243-8_17
- Description: This paper presents an investigative analysis of net-work scans and scan detection algorithms. Visualisa-tion is employed to review network telescope traffic and identify incidents of scan activity. Some of the identified phenomena appear to be novel forms of host discovery. Scan detection algorithms used by the Snort and Bro intrusion detection systems are cri-tiqued by comparing the visualised scans with alert output. Where human assessment disagrees with the alert output, explanations are sought by analysing the detection algorithms. The Snort and Bro algorithms are based on counting unique connection attempts to destination addresses and ports. For Snort, notable false positive and false negative cases result due to a grossly oversimplified method of counting unique destination addresses and ports.
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Viewpoint: reading conference recommendations in a wider context of social change
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67411 , vital:29085 , https://www.ajol.info/index.php/sajee/article/view/122783
- Description: publisher version , 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.
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- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67411 , vital:29085 , https://www.ajol.info/index.php/sajee/article/view/122783
- Description: publisher version , 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.
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