Cytotoxicity, phytochemical analysis and antioxidant activity of crude extracts from Rhizomes of Elephantorrhiza Elephantina and Pentanisia Prunelloides
- Mpofu, Smart J, Msagati, Titus A M, Krause, Rui W M
- Authors: Mpofu, Smart J , Msagati, Titus A M , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125097 , vital:35728 , https://doi.org/10.4314/ajtcam.v11i1.6
- Description: Background: Elephantorrhiza elephantina (Ee) and Pentanisia prunelloides (Pp) are two medicinal plants which are widely used to remedy various ailments including diarrhoea, dysentery, inflammation, fever, rheumatism, heartburn, tuberculosis, haemorrhoids, skin diseases, perforated peptic ulcers and sore joints in southern Africa (South Africa, Swaziland, Botswana and Zimbabwe). The following study was conducted to explore the in vitro cytotoxicity, antioxidant properties and phytochemical profile of the two medicinal plants. Materials and Methods: The cytotoxicity of the aqueous and methanol extracts and fractions of both species was studied using the brine shrimp lethality tests (BST) for the first time. Results: The results demonstrated that the lethality (LC50) for crude extracts for both plants ranged between 1.8 and 5.8 ppm and was relatively greater than that for the methanol, ethyl acetate and chloroform fractions of the extracts which ranged between 2.1 ppm and 27 ppm. This suggested that crude extracts were more potent than their respective fractions, further explaining that the different fractions of phytochemicals in these plant species work jointly (in synergy) to exert their therapeutic efficacy. Both aqueous and methanol extracts of the two medicinal plants demonstrated a high degree of antioxidant capacity against the DPPH radical with the Duh and Yen inhibition percentage ranging between 4.5% and 72%. Phytochemical studies of the rhizome extracts showed that the major compounds present include flavonoids, tannins, anthocyanidins, anthraquinones, triterpenoids (oleanolic acid), the steroidal saponin Diosgenin, the sugars, rhamnose, glucuronic acid, Arabinose and hexoses. Conclusion: This is the first report of the detection and isolation of diosgenin and oleanolic acid from the rhizome extracts of Ee and Pp. All structures were determined using spectroscopic/spectrometric techniques (1H NMR and 13C and LC-ESI-MS) and by comparison with literature data.
- Full Text:
- Date Issued: 2014
- Authors: Mpofu, Smart J , Msagati, Titus A M , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125097 , vital:35728 , https://doi.org/10.4314/ajtcam.v11i1.6
- Description: Background: Elephantorrhiza elephantina (Ee) and Pentanisia prunelloides (Pp) are two medicinal plants which are widely used to remedy various ailments including diarrhoea, dysentery, inflammation, fever, rheumatism, heartburn, tuberculosis, haemorrhoids, skin diseases, perforated peptic ulcers and sore joints in southern Africa (South Africa, Swaziland, Botswana and Zimbabwe). The following study was conducted to explore the in vitro cytotoxicity, antioxidant properties and phytochemical profile of the two medicinal plants. Materials and Methods: The cytotoxicity of the aqueous and methanol extracts and fractions of both species was studied using the brine shrimp lethality tests (BST) for the first time. Results: The results demonstrated that the lethality (LC50) for crude extracts for both plants ranged between 1.8 and 5.8 ppm and was relatively greater than that for the methanol, ethyl acetate and chloroform fractions of the extracts which ranged between 2.1 ppm and 27 ppm. This suggested that crude extracts were more potent than their respective fractions, further explaining that the different fractions of phytochemicals in these plant species work jointly (in synergy) to exert their therapeutic efficacy. Both aqueous and methanol extracts of the two medicinal plants demonstrated a high degree of antioxidant capacity against the DPPH radical with the Duh and Yen inhibition percentage ranging between 4.5% and 72%. Phytochemical studies of the rhizome extracts showed that the major compounds present include flavonoids, tannins, anthocyanidins, anthraquinones, triterpenoids (oleanolic acid), the steroidal saponin Diosgenin, the sugars, rhamnose, glucuronic acid, Arabinose and hexoses. Conclusion: This is the first report of the detection and isolation of diosgenin and oleanolic acid from the rhizome extracts of Ee and Pp. All structures were determined using spectroscopic/spectrometric techniques (1H NMR and 13C and LC-ESI-MS) and by comparison with literature data.
- Full Text:
- Date Issued: 2014
Dependence on environmental resources and implications for household welfare: evidence from the Kalahari drylands, South Africa
- Thondhlana, Gladman, Muchapondwa, Edwin
- Authors: Thondhlana, Gladman , Muchapondwa, Edwin
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67810 , vital:29149 , https://doi.org/10.1016/j.ecolecon.2014.10.003
- Description: Publisher version , This paper examines dependence on environmental resources and impacts on household welfare among the indigenous San and Mier rural communities neighbouring Kgalagadi Transfrontier Park in South Africa. Data on the various household income types, including environmental income, were collected through a structured survey of 200 households. Environmental income constituted 20% of the total income. The poorest income quintile showed the highest relative dependence on environmental income (31%), though absolute environmental income increased with total income. Poverty analyses showed that poverty incidence and poverty gap would increase by 13 and 7 percentage points respectively without environmental income. Gini-coefficient analyses revealed that income inequality would increase by 6 percentage points for all households if environmental income was excluded. The results generally suggest that environmental income is important for both the poor and the well-off, and wealth accumulation might be tied to resource use. There is a case for promoting sound environmental management, and sustainable and fair resource use in the Kalahari drylands in order to help pull more households out of poverty. Our findings also point to issues of heterogeneity in resource access even among indigenous communities previously thought to be homogenous. These should be key considerations for conservation interventions.
- Full Text: false
- Date Issued: 2014
- Authors: Thondhlana, Gladman , Muchapondwa, Edwin
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67810 , vital:29149 , https://doi.org/10.1016/j.ecolecon.2014.10.003
- Description: Publisher version , This paper examines dependence on environmental resources and impacts on household welfare among the indigenous San and Mier rural communities neighbouring Kgalagadi Transfrontier Park in South Africa. Data on the various household income types, including environmental income, were collected through a structured survey of 200 households. Environmental income constituted 20% of the total income. The poorest income quintile showed the highest relative dependence on environmental income (31%), though absolute environmental income increased with total income. Poverty analyses showed that poverty incidence and poverty gap would increase by 13 and 7 percentage points respectively without environmental income. Gini-coefficient analyses revealed that income inequality would increase by 6 percentage points for all households if environmental income was excluded. The results generally suggest that environmental income is important for both the poor and the well-off, and wealth accumulation might be tied to resource use. There is a case for promoting sound environmental management, and sustainable and fair resource use in the Kalahari drylands in order to help pull more households out of poverty. Our findings also point to issues of heterogeneity in resource access even among indigenous communities previously thought to be homogenous. These should be key considerations for conservation interventions.
- Full Text: false
- Date Issued: 2014
Design of a Network Packet Processing platform
- Pennefather, Sean, Irwin, Barry V W
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427901 , vital:72472 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622772_Design_of_a_Network_Packet_Processing_platform/links/5b9a187f92851c4ba8181bd6/Design-of-a-Network-Packet-Processing-platform.pdf
- Description: This paper describes the design considerations investigated in the implementation of a prototype embedded network packet processing platform. The purpose of this system is to provide a means for researchers to process, and manipulate network traffic using an embedded standalone hardware platform, with the provision this be soft-configurable and flexible in its functionality. The performance of the Ethernet layer subsystem implemented using XMOS MCU’s is investigated. Future applications of this prototype are discussed.
- Full Text:
- Date Issued: 2014
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427901 , vital:72472 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622772_Design_of_a_Network_Packet_Processing_platform/links/5b9a187f92851c4ba8181bd6/Design-of-a-Network-Packet-Processing-platform.pdf
- Description: This paper describes the design considerations investigated in the implementation of a prototype embedded network packet processing platform. The purpose of this system is to provide a means for researchers to process, and manipulate network traffic using an embedded standalone hardware platform, with the provision this be soft-configurable and flexible in its functionality. The performance of the Ethernet layer subsystem implemented using XMOS MCU’s is investigated. Future applications of this prototype are discussed.
- Full Text:
- Date Issued: 2014
Development and evaluation of pictograms on medication labels for patients with limited literacy skills in a culturally diverse multiethnic population:
- Kheir, Nadir, Awaisu, Ahmed, Radoui, Amina, El Badawi, Aya, Jean, Linda, Dowse, Roslind
- Authors: Kheir, Nadir , Awaisu, Ahmed , Radoui, Amina , El Badawi, Aya , Jean, Linda , Dowse, Roslind
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156720 , vital:40041 , https://doi.org/10.1016/j.sapharm.2013.11.003
- Description: Much of the migrant workforce in Qatar is of low literacy level and does not understand Arabic or English, presenting a significant challenge to health care professionals. Medicine labels are typically in Arabic and English and are therefore poorly understood by these migrant workers. To develop pictograms illustrating selected medicine label instructions and to evaluate comprehension of the pictograms or conventional text supported with verbal instructions in foreign workers with low literacy skills.
- Full Text:
- Date Issued: 2014
- Authors: Kheir, Nadir , Awaisu, Ahmed , Radoui, Amina , El Badawi, Aya , Jean, Linda , Dowse, Roslind
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156720 , vital:40041 , https://doi.org/10.1016/j.sapharm.2013.11.003
- Description: Much of the migrant workforce in Qatar is of low literacy level and does not understand Arabic or English, presenting a significant challenge to health care professionals. Medicine labels are typically in Arabic and English and are therefore poorly understood by these migrant workers. To develop pictograms illustrating selected medicine label instructions and to evaluate comprehension of the pictograms or conventional text supported with verbal instructions in foreign workers with low literacy skills.
- Full Text:
- Date Issued: 2014
Development of Graphene/CdSe Quantum Dots‐Co Phthalocyanine Nanocomposite for Oxygen Reduction Reaction
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189944 , vital:44950 , xlink:href="https://doi.org/10.1002/elan.201400372"
- Description: Nanocomposites containing CdSe quantum dots, tetra(4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II)) (CoPyPc) and reduced graphene nanosheets (rGNS) were devoloped and used for the modification of a glassy carbon electrode. Characterization of the nanocomposites was done by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. Cyclic voltammetry (CV) was used for electrochemical characterization of the prepared nanocomposite for oxygen reduction reaction. The oxygen reduction activity for rGNS/CdSe-CoPyPc nanocomposite was found to be superior over the individual nanomaterials in this study. The activity of the nanocomposite towards oxygen reduction was also tested for tolerance to methanol crossover effect using chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) studies.
- Full Text:
- Date Issued: 2014
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189944 , vital:44950 , xlink:href="https://doi.org/10.1002/elan.201400372"
- Description: Nanocomposites containing CdSe quantum dots, tetra(4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II)) (CoPyPc) and reduced graphene nanosheets (rGNS) were devoloped and used for the modification of a glassy carbon electrode. Characterization of the nanocomposites was done by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. Cyclic voltammetry (CV) was used for electrochemical characterization of the prepared nanocomposite for oxygen reduction reaction. The oxygen reduction activity for rGNS/CdSe-CoPyPc nanocomposite was found to be superior over the individual nanomaterials in this study. The activity of the nanocomposite towards oxygen reduction was also tested for tolerance to methanol crossover effect using chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) studies.
- Full Text:
- Date Issued: 2014
Diagnosing the sexual pattern of Diplodus cervinus hottentotus (Pisces: Sparidae) from southern Angola
- Winkler, Alexander C, Santos, Carmen V D, Potts, Warren M
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124286 , vital:35589 , https://doi.10.1007/s11160-006-9034-6
- Description: The sexual pattern of Diplodus cervinus hottentotus was investigated in southern Angola. Females were significantly smaller and found in greater numbers, with an adult sex ratio of 1.0:0.7, F:M. Histological observations of preserved gonads indicated that the species is a rudimentary hermaphrodite, possessing a non-functional bisexual ovotestis before maturation. Histological examination of five macroscopically staged ‘bisexual’ individuals revealed that they were functional males with residual ovarian tissue in the gonad, which had persisted from a juvenile bisexual stage. Although empirical population structure and macroscopic observations suggested protogyny, histological evidence suggested otherwise, confirming the need for the use of histology when diagnosing the sexual pattern of sparid fishes.
- Full Text:
- Date Issued: 2014
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124286 , vital:35589 , https://doi.10.1007/s11160-006-9034-6
- Description: The sexual pattern of Diplodus cervinus hottentotus was investigated in southern Angola. Females were significantly smaller and found in greater numbers, with an adult sex ratio of 1.0:0.7, F:M. Histological observations of preserved gonads indicated that the species is a rudimentary hermaphrodite, possessing a non-functional bisexual ovotestis before maturation. Histological examination of five macroscopically staged ‘bisexual’ individuals revealed that they were functional males with residual ovarian tissue in the gonad, which had persisted from a juvenile bisexual stage. Although empirical population structure and macroscopic observations suggested protogyny, histological evidence suggested otherwise, confirming the need for the use of histology when diagnosing the sexual pattern of sparid fishes.
- Full Text:
- Date Issued: 2014
Differential motif enrichment analysis of paired ChIP-seq experiments
- Lesluyes, Tom, Johnson, James, Machanick, Philip, Bailey, Timothy L
- Authors: Lesluyes, Tom , Johnson, James , Machanick, Philip , Bailey, Timothy L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439250 , vital:73559 , https://doi.org/10.1186/1471-2164-15-752
- Description: Motif enrichment analysis of transcription factor ChIP-seq data can help identify transcription factors that cooperate or compete. Previously, little attention has been given to comparative motif enrichment analysis of pairs of ChIP-seq experiments, where the binding of the same transcription factor is assayed under different conditions. Such comparative analysis could potentially identify the distinct regulatory partners/competitors of the assayed transcription factor under different conditions or at different stages of development.
- Full Text:
- Date Issued: 2014
- Authors: Lesluyes, Tom , Johnson, James , Machanick, Philip , Bailey, Timothy L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439250 , vital:73559 , https://doi.org/10.1186/1471-2164-15-752
- Description: Motif enrichment analysis of transcription factor ChIP-seq data can help identify transcription factors that cooperate or compete. Previously, little attention has been given to comparative motif enrichment analysis of pairs of ChIP-seq experiments, where the binding of the same transcription factor is assayed under different conditions. Such comparative analysis could potentially identify the distinct regulatory partners/competitors of the assayed transcription factor under different conditions or at different stages of development.
- Full Text:
- Date Issued: 2014
Digital disruption: some instagrams
- Authors: Garman, Anthea
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144558 , vital:38357 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC159516
- Description: I'm going to shamelessly pinch someone else's language to think about the changes and challenges of this media moment we are living through and take the theme for the Mennel Media Exchange (MMX14), organised by Laurie Bley of Duke University and Patrick Conroy of eNCA and held in Johannesburg in July. “ Digital disruption" doesn't fallen into the neat pessimism or optimism so emblematic of our times but does say forcefully that we are all on uncertain ground and need to reconfigure our ways of doing and being in media making, media managing and in education.
- Full Text:
- Date Issued: 2014
- Authors: Garman, Anthea
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144558 , vital:38357 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC159516
- Description: I'm going to shamelessly pinch someone else's language to think about the changes and challenges of this media moment we are living through and take the theme for the Mennel Media Exchange (MMX14), organised by Laurie Bley of Duke University and Patrick Conroy of eNCA and held in Johannesburg in July. “ Digital disruption" doesn't fallen into the neat pessimism or optimism so emblematic of our times but does say forcefully that we are all on uncertain ground and need to reconfigure our ways of doing and being in media making, media managing and in education.
- Full Text:
- Date Issued: 2014
Digital multimedia network with parameter join mechanism
- Gurdan, Robby, Foss, Richard
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427059 , vital:72411 , https://patentimages.storage.googleapis.com/ae/e3/6a/0afc332b8afaea/US8855008.pdf
- Description: A digital multimedia network with a parameter join mechanism comprising at least one apparatus. A requesting device parameter of a source apparatus updates a local parameter group list by adding an entry for each device parameter of a target apparatus which joins the parameter group.
- Full Text:
- Date Issued: 2014
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427059 , vital:72411 , https://patentimages.storage.googleapis.com/ae/e3/6a/0afc332b8afaea/US8855008.pdf
- Description: A digital multimedia network with a parameter join mechanism comprising at least one apparatus. A requesting device parameter of a source apparatus updates a local parameter group list by adding an entry for each device parameter of a target apparatus which joins the parameter group.
- Full Text:
- Date Issued: 2014
E-Literacy training in deep rural areas: The Siyakhula Living Lab experience
- Gumbo, Sibukelo, Ntšekhe, Mathe, Terzoli, Alfredo
- Authors: Gumbo, Sibukelo , Ntšekhe, Mathe , Terzoli, Alfredo
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431411 , vital:72772 , http://proceedings.e-skillsconference.org/2014/e-skills141-154Gumbo824.pdf
- Description: Within the discourse of broadband deployment in poor areas (particular-ly rural), very little attention is generally put on the critical enabler repre-sented by e-literacy training that empowers people to use ICT systems, especially in the form of full-fledged machines such as fixed, tower and laptop computers (These machines are still more preferable for growing a generation of ‘producers’ as opposed to ‘consumers’ in the ICT space.) This paper reports on the experience in running e-literacy in a deep rural area, as part of the Siyakhula Living Lab (SLL), whose end goal is to diffuse production oriented ICTs in poor areas of South Africa and Africa. In particular it will expand on the feedback given by the par-ticipants to the last edition of the e-literacy course, run in the first se-mester of 2014. The lessons learned from this experience include: the need for linguistic localization of the learning material or at least part of its presentation; the importance of teaching and learning that facilitates (easy) transfer of knowledge gained to other ICT settings (such as mo-biles; or uses to support business); and the importance of face-to-face courses to allow real interaction with the people living in the targeted areas, partly as a strategic means to forging relations towards the reali-zation of the Living Lab vision (co-creation of solutions with empowered users). Altogether, e-literacy courses have proved to be critical to the broad aim of SLL of ‘activating’the segment of society living in poor ar-eas towards self-determination. A small but telling indicator is the trans-formation in the view people have of themselves once certified as e-literate.
- Full Text:
- Date Issued: 2014
- Authors: Gumbo, Sibukelo , Ntšekhe, Mathe , Terzoli, Alfredo
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431411 , vital:72772 , http://proceedings.e-skillsconference.org/2014/e-skills141-154Gumbo824.pdf
- Description: Within the discourse of broadband deployment in poor areas (particular-ly rural), very little attention is generally put on the critical enabler repre-sented by e-literacy training that empowers people to use ICT systems, especially in the form of full-fledged machines such as fixed, tower and laptop computers (These machines are still more preferable for growing a generation of ‘producers’ as opposed to ‘consumers’ in the ICT space.) This paper reports on the experience in running e-literacy in a deep rural area, as part of the Siyakhula Living Lab (SLL), whose end goal is to diffuse production oriented ICTs in poor areas of South Africa and Africa. In particular it will expand on the feedback given by the par-ticipants to the last edition of the e-literacy course, run in the first se-mester of 2014. The lessons learned from this experience include: the need for linguistic localization of the learning material or at least part of its presentation; the importance of teaching and learning that facilitates (easy) transfer of knowledge gained to other ICT settings (such as mo-biles; or uses to support business); and the importance of face-to-face courses to allow real interaction with the people living in the targeted areas, partly as a strategic means to forging relations towards the reali-zation of the Living Lab vision (co-creation of solutions with empowered users). Altogether, e-literacy courses have proved to be critical to the broad aim of SLL of ‘activating’the segment of society living in poor ar-eas towards self-determination. A small but telling indicator is the trans-formation in the view people have of themselves once certified as e-literate.
- Full Text:
- Date Issued: 2014
Echoes of colonial discourse in journalism:
- Authors: Wasserman, Herman
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159891 , vital:40353 , https://doi.org/10.1080/02560054.2014.886657
- Description: Last year marked the 200th anniversary of the birth of David Livingstone, the explorer and missionary who is best remembered as an anti-slavery campaigner who presented Africa in humanitarian terms to the British Empire. Today the legacy of colonialism continues to haunt the continent, and the discourses of colonialism can still be heard in media representations of Africa.
- Full Text:
- Date Issued: 2014
- Authors: Wasserman, Herman
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159891 , vital:40353 , https://doi.org/10.1080/02560054.2014.886657
- Description: Last year marked the 200th anniversary of the birth of David Livingstone, the explorer and missionary who is best remembered as an anti-slavery campaigner who presented Africa in humanitarian terms to the British Empire. Today the legacy of colonialism continues to haunt the continent, and the discourses of colonialism can still be heard in media representations of Africa.
- Full Text:
- Date Issued: 2014
Editorial
- Authors: Olvitt, Lausanne L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391156 , vital:68625 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/121960"
- Description: This year marks the end of the United Nations Decade of Education for Sustainable Development which was first proposed at the World Summit on Sustainable Development in 2002 in Johannesburg. At the end of 2014 UNESCO hosted the World Conference on Education for Sustainable Development in Nagoya, Japan. To mark this occasion Professor Rob O’Donoghue produced a reflective Think Piece that traces the emergence of education for sustainable development (ESD) from its educational roots in the Modernist project, to the diversity of practices that currently frame ESD as a transgressive process of cultural change. O’Donoghue interrogates tensions around knowledge and participation in the ESD terrain and proposes that knowledge-led and ethics-led learning in relation to valued purposes might create educational possibilities for expansive, transgressive and reflexive learning processes towards a more sustainable future. This Think Piece opens the Journal; many of the strengths, tensions and generative opportunities in environment and sustainability education referred to by O’Donoghue are reflected in this edition of the journal.
- Full Text:
- Date Issued: 2014
- Authors: Olvitt, Lausanne L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391156 , vital:68625 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/121960"
- Description: This year marks the end of the United Nations Decade of Education for Sustainable Development which was first proposed at the World Summit on Sustainable Development in 2002 in Johannesburg. At the end of 2014 UNESCO hosted the World Conference on Education for Sustainable Development in Nagoya, Japan. To mark this occasion Professor Rob O’Donoghue produced a reflective Think Piece that traces the emergence of education for sustainable development (ESD) from its educational roots in the Modernist project, to the diversity of practices that currently frame ESD as a transgressive process of cultural change. O’Donoghue interrogates tensions around knowledge and participation in the ESD terrain and proposes that knowledge-led and ethics-led learning in relation to valued purposes might create educational possibilities for expansive, transgressive and reflexive learning processes towards a more sustainable future. This Think Piece opens the Journal; many of the strengths, tensions and generative opportunities in environment and sustainability education referred to by O’Donoghue are reflected in this edition of the journal.
- Full Text:
- Date Issued: 2014
Editors reflect on the state of journalism: the cha(lle)nging media space
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158650 , vital:40218 , https://hdl.handle.net/10520/EJC159502
- Description: Trying to understand how journalists and editors in the South African media landscape think about the work they do and the environment in which they work is not easy. However, while many of us speculate about why things are reported on in one way or another, this article gets to the heart of the issue - or the mouth - by speaking to journalists and editors about the work they do and how things have changed in the last few years within this complex institution we call the media.
- Full Text:
- Date Issued: 2014
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158650 , vital:40218 , https://hdl.handle.net/10520/EJC159502
- Description: Trying to understand how journalists and editors in the South African media landscape think about the work they do and the environment in which they work is not easy. However, while many of us speculate about why things are reported on in one way or another, this article gets to the heart of the issue - or the mouth - by speaking to journalists and editors about the work they do and how things have changed in the last few years within this complex institution we call the media.
- Full Text:
- Date Issued: 2014
Effect of bovine serum albumin and single walled carbon nanotube on the photophysical properties of zinc octacarboxy phthalocyanine
- Ogbodu, Racheal O, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189806 , vital:44933 , xlink:href="https://doi.org/10.1016/j.saa.2013.10.064"
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased.
- Full Text:
- Date Issued: 2014
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189806 , vital:44933 , xlink:href="https://doi.org/10.1016/j.saa.2013.10.064"
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased.
- Full Text:
- Date Issued: 2014
Effect of water trophic level on the impact of the water hyacinth moth Niphograpta albiguttalis on Eichhornia crassipes
- Canavan, Kim N, Coetzee, Julie A, Hill, Martin P, Paterson, Iain D
- Authors: Canavan, Kim N , Coetzee, Julie A , Hill, Martin P , Paterson, Iain D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423740 , vital:72090 , xlink:href="https://doi.org/10.2989/16085914.2014.893225"
- Description: Eutrophication contributes to the proliferation of alien invasive weed species such as water hyacinth Eichhornia crassipes. Although the South American moth Niphograpta albiguttalis was released in South Africa in 1990 as a biological control agent against water hyacinth, no post-release evaluations have yet been conducted here. The impact of N. albiguttalis on water hyacinth growth was quantified under low-, medium- and high-nutrient concentrations in a greenhouse experiment. Niphograpta albiguttalis was damaging to water hyacinth in all three nutrient treatments, but significant damage in most plant parameters was found only under high-nutrient treatments. However, E. crassipes plants grown in high-nutrient water were healthier, and presumably had higher fitness, than plants not exposed to herbivory at lower-nutrient levels. Niphograpta albiguttalis is likely to be most damaging to water hyacinth in eutrophic water systems, but the damage will not result in acceptable levels of control because of the plant's high productivity under these conditions. Niphograpta albiguttalis is a suitable agent for controlling water hyacinth infestations in eutrophic water systems, but should be used in combination with other biological control agents and included in an integrated management plan also involving herbicidal control and water quality management.
- Full Text:
- Date Issued: 2014
- Authors: Canavan, Kim N , Coetzee, Julie A , Hill, Martin P , Paterson, Iain D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423740 , vital:72090 , xlink:href="https://doi.org/10.2989/16085914.2014.893225"
- Description: Eutrophication contributes to the proliferation of alien invasive weed species such as water hyacinth Eichhornia crassipes. Although the South American moth Niphograpta albiguttalis was released in South Africa in 1990 as a biological control agent against water hyacinth, no post-release evaluations have yet been conducted here. The impact of N. albiguttalis on water hyacinth growth was quantified under low-, medium- and high-nutrient concentrations in a greenhouse experiment. Niphograpta albiguttalis was damaging to water hyacinth in all three nutrient treatments, but significant damage in most plant parameters was found only under high-nutrient treatments. However, E. crassipes plants grown in high-nutrient water were healthier, and presumably had higher fitness, than plants not exposed to herbivory at lower-nutrient levels. Niphograpta albiguttalis is likely to be most damaging to water hyacinth in eutrophic water systems, but the damage will not result in acceptable levels of control because of the plant's high productivity under these conditions. Niphograpta albiguttalis is a suitable agent for controlling water hyacinth infestations in eutrophic water systems, but should be used in combination with other biological control agents and included in an integrated management plan also involving herbicidal control and water quality management.
- Full Text:
- Date Issued: 2014
Effects of analytes on the fluorescence properties of CdTe@ ZnS quantum dots decorated with cobalt tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
- Date Issued: 2014
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
- Date Issued: 2014
Effects of number of ring substituents on the physicochemical properties of zinc aminophenoxy phthalocyanine-single walled carbon nanotube conjugate
- Ogbodu, Rachael O, Nyokong, Tebello
- Authors: Ogbodu, Rachael O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190356 , vital:44987 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.09.015"
- Description: This work reports on the linking of zinc monoaminophenoxy (ZnMAPPc) or zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) complexes to single walled carbon nanotubes (SWCNTs) through either covalent or non-covalent (adsorption) bonding. The functionalized complexes showed better thermal stability when compared to the SWCNT-COOH, ZnMAPPc and ZnTAPPc alone as confirmed by thermogravimetric analyses. The covalently linked ZnMAPc-SWCNT showed higher electron transfer rate constant and photoinduced electron efficiency when compared to adsorbed complexes. ZnMAPPc-SWCNT complexes (linked and adsorbed) showed better photophysical and photochemical properties when compared to ZnTAPPc-SWCNT complexes. The triplet, singlet oxygen and florescence quantum yields of ZnMAPPc (or ZnTAPPc) decrease upon linking or adsorption onto SWCNTs.
- Full Text:
- Date Issued: 2014
- Authors: Ogbodu, Rachael O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190356 , vital:44987 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.09.015"
- Description: This work reports on the linking of zinc monoaminophenoxy (ZnMAPPc) or zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) complexes to single walled carbon nanotubes (SWCNTs) through either covalent or non-covalent (adsorption) bonding. The functionalized complexes showed better thermal stability when compared to the SWCNT-COOH, ZnMAPPc and ZnTAPPc alone as confirmed by thermogravimetric analyses. The covalently linked ZnMAPc-SWCNT showed higher electron transfer rate constant and photoinduced electron efficiency when compared to adsorbed complexes. ZnMAPPc-SWCNT complexes (linked and adsorbed) showed better photophysical and photochemical properties when compared to ZnTAPPc-SWCNT complexes. The triplet, singlet oxygen and florescence quantum yields of ZnMAPPc (or ZnTAPPc) decrease upon linking or adsorption onto SWCNTs.
- Full Text:
- Date Issued: 2014
Effects of pyrene on the photophysical and two-photon absorption-based nonlinear optical properties of indium (III) phthalocyanines
- Sanusi, Kayode, Nyokong, Tebello
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189957 , vital:44951 , xlink:href="https://doi.org/10.1080/00958972.2014.959509"
- Description: Photophysical and two-photon-dependent nonlinear absorption properties of two chloroindium(III) phthalocyanines bearing pyrene units have been investigated. The tetra- (3) and the tri- (4) pyrene-substituted phthalocyanines exhibit strong triplet absorption with high triplet yields ( ) of 0.79 and 0.83, respectively. The measured nonlinear optical data, such as the two photon absorption cross-sections, the third- and second-order nonlinearities were found to be comparable with those of literature, thus, making the compounds promising candidates for a broad range of nonlinear optical applications.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189957 , vital:44951 , xlink:href="https://doi.org/10.1080/00958972.2014.959509"
- Description: Photophysical and two-photon-dependent nonlinear absorption properties of two chloroindium(III) phthalocyanines bearing pyrene units have been investigated. The tetra- (3) and the tri- (4) pyrene-substituted phthalocyanines exhibit strong triplet absorption with high triplet yields ( ) of 0.79 and 0.83, respectively. The measured nonlinear optical data, such as the two photon absorption cross-sections, the third- and second-order nonlinearities were found to be comparable with those of literature, thus, making the compounds promising candidates for a broad range of nonlinear optical applications.
- Full Text:
- Date Issued: 2014
Effects of redox mediators on the catalytic activity of iron porphyrins towards oxygen reduction in acidic media
- He, Qinggang, Wu, Gang, Liu, Ke, Khene, Samson M, Li, Qing, Mugadza, Tawanda, Deunf, Elise, Nyokong, Tebello, Chen, Shaowei W
- Authors: He, Qinggang , Wu, Gang , Liu, Ke , Khene, Samson M , Li, Qing , Mugadza, Tawanda , Deunf, Elise , Nyokong, Tebello , Chen, Shaowei W
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241472 , vital:50942 , xlink:href="https://doi.org/10.1002/celc.201402054"
- Description: The effects of different redox mediators on the oxygen reduction reaction (ORR) catalyzed by an iron porphyrin complex, iron(III) meso-tetra(N-methyl-4-pyridyl)porphine chloride [FeIIITMPyP], in 0.1 M triflic acid were investigated by cyclic voltammetry (CV) and spectroelectrochemistry in conjunction with density functional theory (DFT) calculations. The formal potentials of the FeIIITMPyP catalyst and the redox mediators, as well as the half-wave potentials for the ORR, were determined by CV in the absence and presence of oxygen in acidic solutions. UV/Vis spectroscopic and spectroelectrochemical studies confirmed that only the 2,2′-azino-bis(3-ethylbenzothiazioline-6-sulfonic acid)diammonium salt (C18H24N6O6S4) showed effective interactions with FeIIITMPyP during the ORR. DFT calculations suggested strong interaction between FeIIITMPyP and the C18H24N6O6S4 redox mediator. The redox mediator caused lengthening of the dioxygen iron bond, which thus suggested easier dioxygen reduction. Consistent results were observed in electrochemical impedance spectroscopic measurements for which the electron-transfer kinetics were also evaluated.
- Full Text:
- Date Issued: 2014
- Authors: He, Qinggang , Wu, Gang , Liu, Ke , Khene, Samson M , Li, Qing , Mugadza, Tawanda , Deunf, Elise , Nyokong, Tebello , Chen, Shaowei W
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241472 , vital:50942 , xlink:href="https://doi.org/10.1002/celc.201402054"
- Description: The effects of different redox mediators on the oxygen reduction reaction (ORR) catalyzed by an iron porphyrin complex, iron(III) meso-tetra(N-methyl-4-pyridyl)porphine chloride [FeIIITMPyP], in 0.1 M triflic acid were investigated by cyclic voltammetry (CV) and spectroelectrochemistry in conjunction with density functional theory (DFT) calculations. The formal potentials of the FeIIITMPyP catalyst and the redox mediators, as well as the half-wave potentials for the ORR, were determined by CV in the absence and presence of oxygen in acidic solutions. UV/Vis spectroscopic and spectroelectrochemical studies confirmed that only the 2,2′-azino-bis(3-ethylbenzothiazioline-6-sulfonic acid)diammonium salt (C18H24N6O6S4) showed effective interactions with FeIIITMPyP during the ORR. DFT calculations suggested strong interaction between FeIIITMPyP and the C18H24N6O6S4 redox mediator. The redox mediator caused lengthening of the dioxygen iron bond, which thus suggested easier dioxygen reduction. Consistent results were observed in electrochemical impedance spectroscopic measurements for which the electron-transfer kinetics were also evaluated.
- Full Text:
- Date Issued: 2014
Electrocatalytic behahiour of cobalt tetraamino-phthalocyanine in the presence of a composite of reduced graphene nanosheets and of multi-walled carbon nanotubes
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189784 , vital:44931 , xlink:href="https://doi.org/10.1016/j.electacta.2014.05.093"
- Description: A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2) was developed in order to minimize the restacking of the latter. The composite was used to modify a glassy carbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). The modified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy were used to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10−8 M towards the detection of paraguat as a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is also proposed in this work.
- Full Text:
- Date Issued: 2014
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189784 , vital:44931 , xlink:href="https://doi.org/10.1016/j.electacta.2014.05.093"
- Description: A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2) was developed in order to minimize the restacking of the latter. The composite was used to modify a glassy carbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). The modified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy were used to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10−8 M towards the detection of paraguat as a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is also proposed in this work.
- Full Text:
- Date Issued: 2014