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
Distributional range of the South African maritime spider-egg parasitoid wasp, Echthrodesis lamorali (Hymenoptera: Platygastridae Scelioninae) insecta hymenoptera
- Owen, Candice A, Coetzee, Julie A, van Noort, Simon
- Authors: Owen, Candice A , Coetzee, Julie A , van Noort, Simon
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444407 , vital:74238 , https://hdl.handle.net/10520/EJC161753
- Description: The southern African coastline plays host to nine spider species. Two of these, namely Desis formidabilis (O. P.-Cambridge, 1890) (Araneae: Desidae) and Amaurobioides africanus Hewitt, 1917 (Araneae: Anyphaenidae), are recorded as hosts for an intertidal spider egg parasitoid, Echthrodesis lamorali Masner, 1968 (Hymenoptera: Platygastridae: Scelioninae). These two spider species occur from Lüderitz (Namibia) along the coast to East London (Eastern Cape Province, South Africa), while their parasitoid has been known from only a single locality on the Cape Peninsula. The South African coastline was surveyed from Jacobsbaai (Western Cape Province) to East London in an attempt to determine the full distribution of E. lamorali. The wasp was only reared from host eggs collected on the Cape Peninsula, confirming a high degree of endemism for this species.
- Full Text:
- Date Issued: 2014
- Authors: Owen, Candice A , Coetzee, Julie A , van Noort, Simon
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444407 , vital:74238 , https://hdl.handle.net/10520/EJC161753
- Description: The southern African coastline plays host to nine spider species. Two of these, namely Desis formidabilis (O. P.-Cambridge, 1890) (Araneae: Desidae) and Amaurobioides africanus Hewitt, 1917 (Araneae: Anyphaenidae), are recorded as hosts for an intertidal spider egg parasitoid, Echthrodesis lamorali Masner, 1968 (Hymenoptera: Platygastridae: Scelioninae). These two spider species occur from Lüderitz (Namibia) along the coast to East London (Eastern Cape Province, South Africa), while their parasitoid has been known from only a single locality on the Cape Peninsula. The South African coastline was surveyed from Jacobsbaai (Western Cape Province) to East London in an attempt to determine the full distribution of E. lamorali. The wasp was only reared from host eggs collected on the Cape Peninsula, confirming a high degree of endemism for this species.
- 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
Electrochemical behaviour of gold nanoparticles and Co tetraaminophthalocyanine on glassy carbon electrode
- Maringa, Audacity, Antunes, Edith M, Nyokong, Tebello
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014
Electrochemical inclusion of catechol into singlewalled carbon nanotubes: application for sensors
- Authors: Oni, Joshua , Limson, Janice
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431090 , vital:72743 , xlink:href="10.1109/BioCAS.2014.6981727"
- Description: We report on the use of catechol for the electrochemical activation of acid-functionalised single-walled carbon nanotubes immobilised on glassy carbon electrodes. Following well-published methods for catechol activation of bare glassy carbon electrodes, these studies show the efficacy of extending the method to activation of carbon nanotubes. Voltammetric scans in catechol show an increase in current response of 37 μA for the catechol redox pair over a maximum of three cycles during the catechol activation step. An increase in the ease of electron flow is indicated by a larger value for K app , which corresponds to a decrease in R ct obtained during impedance measurements. Catechol activation enhanced electron transfer, potentially afforded by an ease of electron passage due to a decrease in the resistance of the layer.
- Full Text:
- Date Issued: 2014
- Authors: Oni, Joshua , Limson, Janice
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431090 , vital:72743 , xlink:href="10.1109/BioCAS.2014.6981727"
- Description: We report on the use of catechol for the electrochemical activation of acid-functionalised single-walled carbon nanotubes immobilised on glassy carbon electrodes. Following well-published methods for catechol activation of bare glassy carbon electrodes, these studies show the efficacy of extending the method to activation of carbon nanotubes. Voltammetric scans in catechol show an increase in current response of 37 μA for the catechol redox pair over a maximum of three cycles during the catechol activation step. An increase in the ease of electron flow is indicated by a larger value for K app , which corresponds to a decrease in R ct obtained during impedance measurements. Catechol activation enhanced electron transfer, potentially afforded by an ease of electron passage due to a decrease in the resistance of the layer.
- Full Text:
- Date Issued: 2014
Electropolymerized Fluorinated Aniline-Based Fiber for Headspace Solid-Phase Microextraction and Gas Chromatographic Determination of Benzaldehyde in Injectable Pharmaceutical Formulations
- Mohammadi, Ali, Mohammadi, Somayeh, Moghaddam, Bayandori A, Masoumi, Vahideh, Walker, Roderick B
- Authors: Mohammadi, Ali , Mohammadi, Somayeh , Moghaddam, Bayandori A , Masoumi, Vahideh , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184120 , vital:44175 , xlink:href="https://doi.org/10.1093/chromsci/bmt152"
- Description: In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography–flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50–800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n 5 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms.
- Full Text:
- Date Issued: 2014
- Authors: Mohammadi, Ali , Mohammadi, Somayeh , Moghaddam, Bayandori A , Masoumi, Vahideh , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184120 , vital:44175 , xlink:href="https://doi.org/10.1093/chromsci/bmt152"
- Description: In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography–flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50–800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n 5 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms.
- Full Text:
- Date Issued: 2014
Electro‐oxidation of acetaminophen on nickel/poly (o‐aminophenol)/multi‐walled carbon nanotube nanocomposite modified graphite electrode.
- Naeemy, Ali, Mohammadi, Ali, Bakhtiari, Hediech, Ashouri, Nasim, Walker, Roderick B
- Authors: Naeemy, Ali , Mohammadi, Ali , Bakhtiari, Hediech , Ashouri, Nasim , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184107 , vital:44173 , xlink:href="https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/mnl.2014.0197"
- Description: Poly(o-aminophenol) (POAP)/multi-walled carbon nanotube (MWCNT) nanocomposite and POAP in the absence of the MWCNT were fabricated by consecutive cyclic voltammetry (CV) on a graphite (G) electrode. The dispersion of nickel (II) ions was accomplished and incorporated into the polymeric electrodes (G/POAP and G/POAP-MWCNT) by immersing them into a 0.1 M nickel (II) solution. Following preparation of G/POAP/Ni and G/POAP-MWCNT/Ni, the electrochemical behaviour was examined using CV. Scanning electron microscopy was used for characterisation of the nanocomposite. The prepared electrodes showed enhanced electrocatalytic activity for the oxidation of acetaminophen and facilitated the detection of acetaminophen in a 0.1 M NaOH solution. Compared with the G/POAP/Ni electrode, the G/POAP-MWCNT/Ni electrode had a significant current response of acetaminophen oxidation because of the synergistic effects of POAP and the MWCNT. By CV, the calibration plot was linear in the range of 1–13 mM with standard deviation between 0.3 and 6.54% for acetaminophen. The G/POAP-MWCNT/Ni was successfully applied for acetaminophen determination in tablets and the results showed sufficient precision and achieved a mean recovery of 96.8% (R.S.D. = 4.9%).
- Full Text:
- Date Issued: 2014
- Authors: Naeemy, Ali , Mohammadi, Ali , Bakhtiari, Hediech , Ashouri, Nasim , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184107 , vital:44173 , xlink:href="https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/mnl.2014.0197"
- Description: Poly(o-aminophenol) (POAP)/multi-walled carbon nanotube (MWCNT) nanocomposite and POAP in the absence of the MWCNT were fabricated by consecutive cyclic voltammetry (CV) on a graphite (G) electrode. The dispersion of nickel (II) ions was accomplished and incorporated into the polymeric electrodes (G/POAP and G/POAP-MWCNT) by immersing them into a 0.1 M nickel (II) solution. Following preparation of G/POAP/Ni and G/POAP-MWCNT/Ni, the electrochemical behaviour was examined using CV. Scanning electron microscopy was used for characterisation of the nanocomposite. The prepared electrodes showed enhanced electrocatalytic activity for the oxidation of acetaminophen and facilitated the detection of acetaminophen in a 0.1 M NaOH solution. Compared with the G/POAP/Ni electrode, the G/POAP-MWCNT/Ni electrode had a significant current response of acetaminophen oxidation because of the synergistic effects of POAP and the MWCNT. By CV, the calibration plot was linear in the range of 1–13 mM with standard deviation between 0.3 and 6.54% for acetaminophen. The G/POAP-MWCNT/Ni was successfully applied for acetaminophen determination in tablets and the results showed sufficient precision and achieved a mean recovery of 96.8% (R.S.D. = 4.9%).
- Full Text:
- Date Issued: 2014
Elephants in Africa: Big, grey biodiversity thieves?
- Kuiper, Timothy R, Parker, Daniel M
- Authors: Kuiper, Timothy R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124385 , vital:35601 , https://doi.org/10.2989/16085914.2011.589120
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are ‘good’ or ‘bad’ for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief – a species that upsets the natural diversity of life in the habitat in which it lives.
- Full Text:
- Date Issued: 2014
- Authors: Kuiper, Timothy R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124385 , vital:35601 , https://doi.org/10.2989/16085914.2011.589120
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are ‘good’ or ‘bad’ for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief – a species that upsets the natural diversity of life in the habitat in which it lives.
- Full Text:
- Date Issued: 2014