Physicochemical behavior of nanohybrids of mono and tetra substituted carboxyphenoxy phthalocyanine covalently linked to GSH–CdTe/CdS/ZnS quantum dots
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7266 , http://hdl.handle.net/10962/d1020275 , http://dx.doi.org/10.1016/j.poly.2014.10.024
- Description: Zinc monocarboxyphenoxy and tetracarboxyphenoxy phthalocyanines were covalently linked with three different sizes of glutathione capped core/shell/shell {CdTe/CdS/ZnS(4.2), CdTe/CdS/ZnS(5.1) and CdTe/CdS/ZnS(6.7)}; a core shell {CdTe/CdS(3.1)} and core {CdTe(2.4)} quantum dots. The physicochemical behavior and Förster resonance energy transfer (FRET) processes of the nanohybrids were investigated. The highest FRET efficiency was observed with CdTe/CdS/ZnS(6.7) nanohybrids with 98% and the least efficiency was observed with CdTe(2.4) nanohybrids with 85%. The CdTe/CdS/ZnS(6.7) also showed the best physicochemical behavior. These good physicochemical properties make the synthesized nanohybrids viable photosensitizers. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.10.024
- Full Text: false
- Date Issued: 2015
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7266 , http://hdl.handle.net/10962/d1020275 , http://dx.doi.org/10.1016/j.poly.2014.10.024
- Description: Zinc monocarboxyphenoxy and tetracarboxyphenoxy phthalocyanines were covalently linked with three different sizes of glutathione capped core/shell/shell {CdTe/CdS/ZnS(4.2), CdTe/CdS/ZnS(5.1) and CdTe/CdS/ZnS(6.7)}; a core shell {CdTe/CdS(3.1)} and core {CdTe(2.4)} quantum dots. The physicochemical behavior and Förster resonance energy transfer (FRET) processes of the nanohybrids were investigated. The highest FRET efficiency was observed with CdTe/CdS/ZnS(6.7) nanohybrids with 98% and the least efficiency was observed with CdTe(2.4) nanohybrids with 85%. The CdTe/CdS/ZnS(6.7) also showed the best physicochemical behavior. These good physicochemical properties make the synthesized nanohybrids viable photosensitizers. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.10.024
- Full Text: false
- Date Issued: 2015
Public foetal images and the regulation of middle-class pregnancy in the online media : a view from South Africa
- Macleod, Catriona I, Howell, Simon
- Authors: Macleod, Catriona I , Howell, Simon
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6307 , http://hdl.handle.net/10962/d1018803 , http://www.tandfonline.com/doi/full/10.1080/13691058.2015.1046138
- Description: Ultrasonography images and their derivatives have been taken up in a range of ‘public’ spaces, including medical textbooks, the media, anti-abortion material, advertising, the Internet and public health facilities. Feminists have critiqued the personification of the foetus, the bifurcation of the woman’s body and the reduction of the pregnant woman to a disembodied womb. What has received less attention is how these images frequently intersect with race, class, gender and heteronormativity in the creation of idealised and normative understandings of pregnancy. This paper focuses on the discursive positioning of pregnant women as ‘mothers’ and foetuses as ‘babies’ in online media targeted at a South African audience, where race and class continue to intersect in complex ways. We show how the ontologically specific understandings of ‘mummies’ and ‘babies’ emerge through the use of foetal images to construct specific understandings of the ‘ideal’ pregnancy. In the process, pregnant women are made responsible for ensuring that their pregnancy conforms to these ideals, which includes the purchasing of the various goods advertised by the websites. Not only does this point to a commodification of pregnancy, but also serves to reinforce a cultural understanding of White, middle-class pregnancy as constituting the normative ‘correct’ form of pregnancy. , Full text access on publisher website: http://www.tandfonline.com/doi/full/10.1080/13691058.2015.1046138
- Full Text: false
- Date Issued: 2015
- Authors: Macleod, Catriona I , Howell, Simon
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6307 , http://hdl.handle.net/10962/d1018803 , http://www.tandfonline.com/doi/full/10.1080/13691058.2015.1046138
- Description: Ultrasonography images and their derivatives have been taken up in a range of ‘public’ spaces, including medical textbooks, the media, anti-abortion material, advertising, the Internet and public health facilities. Feminists have critiqued the personification of the foetus, the bifurcation of the woman’s body and the reduction of the pregnant woman to a disembodied womb. What has received less attention is how these images frequently intersect with race, class, gender and heteronormativity in the creation of idealised and normative understandings of pregnancy. This paper focuses on the discursive positioning of pregnant women as ‘mothers’ and foetuses as ‘babies’ in online media targeted at a South African audience, where race and class continue to intersect in complex ways. We show how the ontologically specific understandings of ‘mummies’ and ‘babies’ emerge through the use of foetal images to construct specific understandings of the ‘ideal’ pregnancy. In the process, pregnant women are made responsible for ensuring that their pregnancy conforms to these ideals, which includes the purchasing of the various goods advertised by the websites. Not only does this point to a commodification of pregnancy, but also serves to reinforce a cultural understanding of White, middle-class pregnancy as constituting the normative ‘correct’ form of pregnancy. , Full text access on publisher website: http://www.tandfonline.com/doi/full/10.1080/13691058.2015.1046138
- Full Text: false
- Date Issued: 2015
Public reproductive health and ‘unintended’ pregnancies: introducing the construct ‘supportability’
- Authors: Macleod, Catriona I
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6313 , http://hdl.handle.net/10962/d1019881 , https://academic.oup.com/jpubhealth/article-lookup/doi/10.1093/pubmed/fdv123
- Description: In this Perspectives paper, I outline the limitations of the concept of ‘intentionality’ in public reproductive health understandings of pregnancy. ‘Intentionality’, ‘plannedness’, ‘wantedness’ and ‘timing’ place individual cognitions, psychology and/or behaviors at the center of public health conceptualizations of pregnancies, thereby leaving the underlying social and structural dynamics under-examined. I propose a model that places ‘supportability’ at the center of thinking about pregnancies and that allows for an analysis of the intersection of individual cognitions, emotions and behavior with micro-level interactive spaces and macro-level issues. , Full text access on Publisher website: https://academic.oup.com/jpubhealth/article-lookup/doi/10.1093/pubmed/fdv123
- Full Text: false
- Date Issued: 2015
- Authors: Macleod, Catriona I
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6313 , http://hdl.handle.net/10962/d1019881 , https://academic.oup.com/jpubhealth/article-lookup/doi/10.1093/pubmed/fdv123
- Description: In this Perspectives paper, I outline the limitations of the concept of ‘intentionality’ in public reproductive health understandings of pregnancy. ‘Intentionality’, ‘plannedness’, ‘wantedness’ and ‘timing’ place individual cognitions, psychology and/or behaviors at the center of public health conceptualizations of pregnancies, thereby leaving the underlying social and structural dynamics under-examined. I propose a model that places ‘supportability’ at the center of thinking about pregnancies and that allows for an analysis of the intersection of individual cognitions, emotions and behavior with micro-level interactive spaces and macro-level issues. , Full text access on Publisher website: https://academic.oup.com/jpubhealth/article-lookup/doi/10.1093/pubmed/fdv123
- Full Text: false
- Date Issued: 2015
Sculpting with fire: celebrating ephemerality at AfrikaBurn 2015 in the Tankwa Karoo, South Africa
- Authors: Steele, John
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/957 , vital:30075
- Description: Land art, and some installation art, is usually aimed at relatively temporarily manipulating the surface of the earth. AfrikaBurn takes place annually in the near-desert of the Tankwa Karoo, South Africa. It is a communal event unique to Africa, and manifests as a fleeting week-long series of interventions in the natural environment, partially aimed at creating and then actively destroying free-standing public sculptures, some of which are huge and intricate. AfrikaBurn gives any one of the thousands of participants an opportunity to be inspired on any scale to generate artworks that take into account a principle that no debris whatsoever is left behind on the surface of the earth after a week-long celebration of creative energies. Unlike, for instance, an artwork built on the edge of the Indian Ocean in the Eastern Cape, where rough tidal seas would ensure gradual destruction, at AfrikaBurn, the sacrificial method of choice is controlled rapid burning, under the direction of a specified firemaster. This paper seeks to unbundle some aspects of land and installation art in Southern Africa with specific reference to AfrikaBurn 2015 events and anti-fracking initiatives. This is within a context that takes into account recognition that even seemingly durable public sculptures are subject to change and may even physically disappear with the passing of time.
- Full Text:
- Date Issued: 2015
- Authors: Steele, John
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/957 , vital:30075
- Description: Land art, and some installation art, is usually aimed at relatively temporarily manipulating the surface of the earth. AfrikaBurn takes place annually in the near-desert of the Tankwa Karoo, South Africa. It is a communal event unique to Africa, and manifests as a fleeting week-long series of interventions in the natural environment, partially aimed at creating and then actively destroying free-standing public sculptures, some of which are huge and intricate. AfrikaBurn gives any one of the thousands of participants an opportunity to be inspired on any scale to generate artworks that take into account a principle that no debris whatsoever is left behind on the surface of the earth after a week-long celebration of creative energies. Unlike, for instance, an artwork built on the edge of the Indian Ocean in the Eastern Cape, where rough tidal seas would ensure gradual destruction, at AfrikaBurn, the sacrificial method of choice is controlled rapid burning, under the direction of a specified firemaster. This paper seeks to unbundle some aspects of land and installation art in Southern Africa with specific reference to AfrikaBurn 2015 events and anti-fracking initiatives. This is within a context that takes into account recognition that even seemingly durable public sculptures are subject to change and may even physically disappear with the passing of time.
- Full Text:
- Date Issued: 2015
Sexual socialisation in Life Orientation manuals versus popular music: responsibilisation versus pleasure, tension and complexity
- Macleod, Catriona I, Moodley, Dale, Saville Young, Lisa
- Authors: Macleod, Catriona I , Moodley, Dale , Saville Young, Lisa
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6309 , http://hdl.handle.net/10962/d1018866
- Description: This paper compares two forms of sexual socialisation to which learners are exposed: the sexuality education components of the Life Orientation (LO) manuals and the lyrical content and videos of popular songs. We performed a textual analysis of the sexual subject positions made available in, first, the LO manuals used in Grade 10 classes and, second, the two songs voted most popular by the Grade 10 learners of two diverse schools in the Eastern Cape. Of interest in this paper is whether and how these two forms of sexual socialisation – one representing state-sanctioned sexual socialisation and the other learners’ chosen cultural expression that represents informal sexual socialisation – dovetail or diverge. Against a backdrop of heterosexuality and an assumption of the ‘adolescent-in-transition’ discourse, the main sexual subject positions featured in the LO manuals are the responsible sexual subject and the sexual victim. A number of sexualised subject positions are portrayed in the songs, with these subject positions depicting sex as a site of pleasure, tension and complexity. Although these two modes of sexual socialisation use different genres of communication, we argue that learners’ choice of songs that depict fluid sexual subject positions can help to inform LO sexuality education in ways that takes learners’ preferred cultural expression seriously and that moves away from the imperative of responsibilisation.
- Full Text:
- Date Issued: 2015
- Authors: Macleod, Catriona I , Moodley, Dale , Saville Young, Lisa
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6309 , http://hdl.handle.net/10962/d1018866
- Description: This paper compares two forms of sexual socialisation to which learners are exposed: the sexuality education components of the Life Orientation (LO) manuals and the lyrical content and videos of popular songs. We performed a textual analysis of the sexual subject positions made available in, first, the LO manuals used in Grade 10 classes and, second, the two songs voted most popular by the Grade 10 learners of two diverse schools in the Eastern Cape. Of interest in this paper is whether and how these two forms of sexual socialisation – one representing state-sanctioned sexual socialisation and the other learners’ chosen cultural expression that represents informal sexual socialisation – dovetail or diverge. Against a backdrop of heterosexuality and an assumption of the ‘adolescent-in-transition’ discourse, the main sexual subject positions featured in the LO manuals are the responsible sexual subject and the sexual victim. A number of sexualised subject positions are portrayed in the songs, with these subject positions depicting sex as a site of pleasure, tension and complexity. Although these two modes of sexual socialisation use different genres of communication, we argue that learners’ choice of songs that depict fluid sexual subject positions can help to inform LO sexuality education in ways that takes learners’ preferred cultural expression seriously and that moves away from the imperative of responsibilisation.
- Full Text:
- Date Issued: 2015
South African crime fiction: sleuthing the State post-1994, African Identities
- Authors: Naidu, Samantha
- Date: 2015
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10962/53912 , vital:26357 , http://dx.doi.org/10.1080/14725843.2015.1009621 , https://orcid.org/0000-0001-9456-8657
- Description: In this essay we demonstrate how the burgeoning field of South African crime fiction has responded to the birth and development of a democratic, post-apartheid South African state. First, an overview of South African crime fiction in the last 20 years is presented. Then the essay presents an argument for South African crime fiction to be regarded as the ‘new political novel’, based on its capacity for socio-political analysis. We use Deon Meyer, arguably South Africa’s most popular and successful crime fiction author, as an exemplar for our argument. In the following section, the genresnob debate and the resurgence of such terms as ‘lowbrow’ and ‘highbrow’ are considered in relation to crime fiction and the role it plays in the socio-cultural arena of post-apartheid South Africa. We conclude with a comment on the significance of popular literary genres for democracy and critical discourses which underpin that democracy. The essay shows that crime fiction is a strong tool for socio-political analysis in a democratic South Africa, because it promotes critical discourse in society, despite being deemed lowbrow or ideologically ambiguous.
- Full Text: false
- Date Issued: 2015
- Authors: Naidu, Samantha
- Date: 2015
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10962/53912 , vital:26357 , http://dx.doi.org/10.1080/14725843.2015.1009621 , https://orcid.org/0000-0001-9456-8657
- Description: In this essay we demonstrate how the burgeoning field of South African crime fiction has responded to the birth and development of a democratic, post-apartheid South African state. First, an overview of South African crime fiction in the last 20 years is presented. Then the essay presents an argument for South African crime fiction to be regarded as the ‘new political novel’, based on its capacity for socio-political analysis. We use Deon Meyer, arguably South Africa’s most popular and successful crime fiction author, as an exemplar for our argument. In the following section, the genresnob debate and the resurgence of such terms as ‘lowbrow’ and ‘highbrow’ are considered in relation to crime fiction and the role it plays in the socio-cultural arena of post-apartheid South Africa. We conclude with a comment on the significance of popular literary genres for democracy and critical discourses which underpin that democracy. The essay shows that crime fiction is a strong tool for socio-political analysis in a democratic South Africa, because it promotes critical discourse in society, despite being deemed lowbrow or ideologically ambiguous.
- Full Text: false
- Date Issued: 2015
Stigma resistance in online child free communities : the limitations of choice rhetoric
- Morison, Tracy, Macleod, Catriona I, Lynch, Ingrid, Mijas, Magda, Shivakumar, Seemanthini T
- Authors: Morison, Tracy , Macleod, Catriona I , Lynch, Ingrid , Mijas, Magda , Shivakumar, Seemanthini T
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6311 , http://hdl.handle.net/10962/d1019799 , http://journals.sagepub.com/doi/10.1177/0361684315603657
- Description: People who are voluntarily childless, or ‘‘childfree,’’ face considerable stigma. Researchers have begun to explore how these individuals respond to stigma, usually focusing on interpersonal stigma management strategies. We explored participants’ responses to stigma in a way that is cognisant of broader social norms and gender power relations. Using a feminist discursive psychology framework, we analysed women’s and men’s computer-assisted communication about their childfree status. Our analysis draws attention to ‘‘identity work’’ in the context of stigma. We show how the strategic use of ‘‘choice’’ rhetoric allowed participants to avoid stigmatised identities and was used in two contradictory ways. On the one hand, participants drew on a ‘‘childfree-by-choice script,’’ which enabled them to hold a positive identity of themselves as autonomous, rational, and responsible decision makers. On the other hand, they mobilised a ‘‘disavowal of choice script’’ that allowed a person who is unable to choose childlessness (for various reasons) to hold a blameless identity regarding deviation from the norm of parenthood. We demonstrate how choice rhetoric allowed participants to resist stigma and challenge pronatalism to some extent; we discuss the political potential of these scripts for reproductive freedom.
- Full Text:
- Date Issued: 2015
- Authors: Morison, Tracy , Macleod, Catriona I , Lynch, Ingrid , Mijas, Magda , Shivakumar, Seemanthini T
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6311 , http://hdl.handle.net/10962/d1019799 , http://journals.sagepub.com/doi/10.1177/0361684315603657
- Description: People who are voluntarily childless, or ‘‘childfree,’’ face considerable stigma. Researchers have begun to explore how these individuals respond to stigma, usually focusing on interpersonal stigma management strategies. We explored participants’ responses to stigma in a way that is cognisant of broader social norms and gender power relations. Using a feminist discursive psychology framework, we analysed women’s and men’s computer-assisted communication about their childfree status. Our analysis draws attention to ‘‘identity work’’ in the context of stigma. We show how the strategic use of ‘‘choice’’ rhetoric allowed participants to avoid stigmatised identities and was used in two contradictory ways. On the one hand, participants drew on a ‘‘childfree-by-choice script,’’ which enabled them to hold a positive identity of themselves as autonomous, rational, and responsible decision makers. On the other hand, they mobilised a ‘‘disavowal of choice script’’ that allowed a person who is unable to choose childlessness (for various reasons) to hold a blameless identity regarding deviation from the norm of parenthood. We demonstrate how choice rhetoric allowed participants to resist stigma and challenge pronatalism to some extent; we discuss the political potential of these scripts for reproductive freedom.
- Full Text:
- Date Issued: 2015
Structural and optical properties of alloyed quaternary CdSeTeS core and CdSeTeS/ZnS core–shell quantum dots
- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B C
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7244 , http://hdl.handle.net/10962/d1020248
- Description: Synthesis of fluorescent alloyed quantum dots (QDs) with unique optical properties suitable for a wide array of chemical, physical and biological applications is of research interest. In this work, highly luminescent and photostable alloyed quaternary CdSeTeS core QDs of two different sizes were fabricated via the organometallic hot-injection synthetic route. Characterization of the nanocrystals were performed using TEM, XRD, UV/vis and fluorescence spectrophotometric techniques. We have demonstrated in this work that the well fabricated alloyed quaternary CdSeTeS core QDs possess unique optical properties that are advantageous over conventional core/shell systems. Formation of the CdSeTeS/ZnS core/shell with the desired optical properties comes with a number of challenges, hence the advantages of the quaternary alloyed core over the core/shell QDs are (i) avoidance of the challenging process of determining the proper shell thickness which can provide the desired optical properties in the core/shell system and (ii) avoidance of the lattice-induced mismatch between the core and the shell material which can either lead to incomplete exciton confinement or dislocation at the core/shell interface. , Original publication is available at http://dx.doi.org/10.1016/j.jallcom.2015.05.083
- Full Text: false
- Date Issued: 2015
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7244 , http://hdl.handle.net/10962/d1020248
- Description: Synthesis of fluorescent alloyed quantum dots (QDs) with unique optical properties suitable for a wide array of chemical, physical and biological applications is of research interest. In this work, highly luminescent and photostable alloyed quaternary CdSeTeS core QDs of two different sizes were fabricated via the organometallic hot-injection synthetic route. Characterization of the nanocrystals were performed using TEM, XRD, UV/vis and fluorescence spectrophotometric techniques. We have demonstrated in this work that the well fabricated alloyed quaternary CdSeTeS core QDs possess unique optical properties that are advantageous over conventional core/shell systems. Formation of the CdSeTeS/ZnS core/shell with the desired optical properties comes with a number of challenges, hence the advantages of the quaternary alloyed core over the core/shell QDs are (i) avoidance of the challenging process of determining the proper shell thickness which can provide the desired optical properties in the core/shell system and (ii) avoidance of the lattice-induced mismatch between the core and the shell material which can either lead to incomplete exciton confinement or dislocation at the core/shell interface. , Original publication is available at http://dx.doi.org/10.1016/j.jallcom.2015.05.083
- Full Text: false
- Date Issued: 2015
The development of Palladium(II)-specific amine-functionalized silica-based microparticles : adsorption and column separation studies
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Antunes, Edith M, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7270 , http://hdl.handle.net/10962/d1020285
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7270 , http://hdl.handle.net/10962/d1020285
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
The Development of Palladium(II)-Specific Amine-Functionalized Silica-Based Microparticles: Adsorption and Column Separation Studies
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Antunes, Edith M, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7269 , http://hdl.handle.net/10962/d1020278
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7269 , http://hdl.handle.net/10962/d1020278
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
The first world’s third world expert: self-exoticization in Khaled Hosseini's The Kite Runner
- Authors: Naidu, Samantha
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:26358 , http://hdl.handle.net/10962/53922 , http://jcpcsonline.com/contents/ns-v03n1.html , https://orcid.org/0000-0001-9456-8657
- Description: A literary criticism of the book "The Kite Runner" by Khaled Hosseini is presented. It outlines the characters and explores the symbolic significance of these characters. It explores the aspects of contemporary literature among neo-Orientalist representations of the Middle East and the Muslim world. It notes on the contribution of the Euro-American intervention in military and cultural identities of Middle East Orientalists. An overview of the story is also given.
- Full Text: false
- Date Issued: 2015
- Authors: Naidu, Samantha
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:26358 , http://hdl.handle.net/10962/53922 , http://jcpcsonline.com/contents/ns-v03n1.html , https://orcid.org/0000-0001-9456-8657
- Description: A literary criticism of the book "The Kite Runner" by Khaled Hosseini is presented. It outlines the characters and explores the symbolic significance of these characters. It explores the aspects of contemporary literature among neo-Orientalist representations of the Middle East and the Muslim world. It notes on the contribution of the Euro-American intervention in military and cultural identities of Middle East Orientalists. An overview of the story is also given.
- Full Text: false
- Date Issued: 2015
The law of divorce and dissolution of life partnerships in South Africa: book review
- Authors: Kruuse, Helen
- Date: 2015
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54129 , vital:26394 , http://scholar.ufs.ac.za:8080/xmlui/handle/11660/2454
- Description: Jackie Heaton’s latest contribution to the family law domain is formidable – 777 pages of carefully crafted opinions and discussions of the law affecting divorce and dissolution of life partnerships. Given the range, diversity and depth of issues in this area, it is no wonder that she calls on those being among the best in their field to assist her in writing up the book.
- Full Text:
- Date Issued: 2015
- Authors: Kruuse, Helen
- Date: 2015
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54129 , vital:26394 , http://scholar.ufs.ac.za:8080/xmlui/handle/11660/2454
- Description: Jackie Heaton’s latest contribution to the family law domain is formidable – 777 pages of carefully crafted opinions and discussions of the law affecting divorce and dissolution of life partnerships. Given the range, diversity and depth of issues in this area, it is no wonder that she calls on those being among the best in their field to assist her in writing up the book.
- Full Text:
- Date Issued: 2015
The relationship between concurrently measured SASS (South African Scoring System) and turbidity data archived in the South African River Health Programme’s Rivers Database
- Gordon, Andrew K, Griffin, Neil J, Palmer, Carolyn G
- Authors: Gordon, Andrew K , Griffin, Neil J , Palmer, Carolyn G
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7098 , http://hdl.handle.net/10962/d1015956
- Description: The need for monitoring the biological impacts of instream sediments has long been recognised, yet robust and scientifically defensible tools for doing so are still in the early stages of development because of the difficulties experienced by researchers in characterising the complicated mechanisms of biological effect elicited by sediment particles. Biological monitoring is one such tool, and this paper reports on the initial stages of a study to determine the most applicable approach for measuring the effects of instream sediments on aquatic macroinvertebrates in the South African context. In this first instance, the suitability of the rapid macroinvertebrate biomonitoring tool (the South African Scoring System) was investigated by determining the extent of the correlation between concurrently measured SASS metrics and turbidity data collected for the South African River Health Programme. All three SASS metrics – SASS score, number of taxa (NOT), and average score per taxon (ASPT) – were found to be significantly negatively correlated with turbidity, although variation in the data was high. Turbidity was found to be the major driver of change in ASPT. In contrast, electrical conductivity was the major driver of SASS scores and NOT, with turbidity a close second. When combined, electrical conductivity and turbidity accounted for 80 percent (SASS score) and 75 percent (NOT) of the variation in the regression model. Consequently, SASS metrics are a crude, but reliable, indicator of the negative biological implications of excessive instream sedimentation as measured by turbidity. A number of other potential biomonitoring approaches for detecting the impacts of fine sediment exposure are identified for further investigation: spatial analyses of macroinvertebrate assemblages; and the use of structural and functional metrics.
- Full Text:
- Date Issued: 2015
- Authors: Gordon, Andrew K , Griffin, Neil J , Palmer, Carolyn G
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7098 , http://hdl.handle.net/10962/d1015956
- Description: The need for monitoring the biological impacts of instream sediments has long been recognised, yet robust and scientifically defensible tools for doing so are still in the early stages of development because of the difficulties experienced by researchers in characterising the complicated mechanisms of biological effect elicited by sediment particles. Biological monitoring is one such tool, and this paper reports on the initial stages of a study to determine the most applicable approach for measuring the effects of instream sediments on aquatic macroinvertebrates in the South African context. In this first instance, the suitability of the rapid macroinvertebrate biomonitoring tool (the South African Scoring System) was investigated by determining the extent of the correlation between concurrently measured SASS metrics and turbidity data collected for the South African River Health Programme. All three SASS metrics – SASS score, number of taxa (NOT), and average score per taxon (ASPT) – were found to be significantly negatively correlated with turbidity, although variation in the data was high. Turbidity was found to be the major driver of change in ASPT. In contrast, electrical conductivity was the major driver of SASS scores and NOT, with turbidity a close second. When combined, electrical conductivity and turbidity accounted for 80 percent (SASS score) and 75 percent (NOT) of the variation in the regression model. Consequently, SASS metrics are a crude, but reliable, indicator of the negative biological implications of excessive instream sedimentation as measured by turbidity. A number of other potential biomonitoring approaches for detecting the impacts of fine sediment exposure are identified for further investigation: spatial analyses of macroinvertebrate assemblages; and the use of structural and functional metrics.
- Full Text:
- Date Issued: 2015
Visible light transformation of Rhodamine 6G using tetracarbazole zinc phthalocyanine when embedded in electrospun fibers and in the presence of ZnO and Ag particles
- Khoza, Phindile, Nyokong, Tebello
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7246 , http://hdl.handle.net/10962/d1020251
- Description: Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G. , Original publication is available at http://dx.doi.org/10.1080/00958972.2015.1013944
- Full Text: false
- Date Issued: 2015
- Authors: Khoza, Phindile , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7246 , http://hdl.handle.net/10962/d1020251
- Description: Herein, we report the photocatalytic transformation of Rhodamine 6G (Rh 6G) using tetracarbazole zinc phthalocyanine (TCbZnPc) when alone or when conjugated with ZnO macroparticles (ZnOMPs) and silver nanoparticles (AgNPs), represented as TCbZnPc–ZnOMPs and TCbZnPc–AgNPs, respectively. The photocatalysts were supported onto electrospun polystyrene fibers. The efficiency of TCbZnPc was improved by the presence of both ZnOMPs and AgNPs. HPLC equipped with UV–vis was used to study phototransformation products. The mechanism of transformation was via the N-de-ethylation of Rh 6G. , Original publication is available at http://dx.doi.org/10.1080/00958972.2015.1013944
- Full Text: false
- Date Issued: 2015
When is it legitimate to use images in moral arguments? The use of foetal imagery in anti-abortion campaigns as an exemplar of an illegitimate instance of a legitimate practice
- Kelland, Lindsay, Macleod, Catriona I
- Authors: Kelland, Lindsay , Macleod, Catriona I
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6305 , http://hdl.handle.net/10962/d1016146
- Description: We aim to interrogate when the use of images in moral persuasion is legitimate. First, we put forward a number of accounts which purport to show that we can use tools other than logical argumentation to convince others, that such tools evoke affective responses and that these responses have authority in the moral domain. Second, we turn to Sarah McGrath’s account, which focuses on the use of imagery as a means to morally persuade. McGrath discusses 4 objections to the use of imagery, and outlines responses that may be used to legitimate the use of imagery in moral arguments. Assuming that we accept her account and that the invocation of affect has authority in the moral domain, we, using McGrath’s responses, examine whether the use of foetal imagery in anti-abortion campaigns is a legitimate instance of this practice.
- Full Text:
- Date Issued: 2015
- Authors: Kelland, Lindsay , Macleod, Catriona I
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6305 , http://hdl.handle.net/10962/d1016146
- Description: We aim to interrogate when the use of images in moral persuasion is legitimate. First, we put forward a number of accounts which purport to show that we can use tools other than logical argumentation to convince others, that such tools evoke affective responses and that these responses have authority in the moral domain. Second, we turn to Sarah McGrath’s account, which focuses on the use of imagery as a means to morally persuade. McGrath discusses 4 objections to the use of imagery, and outlines responses that may be used to legitimate the use of imagery in moral arguments. Assuming that we accept her account and that the invocation of affect has authority in the moral domain, we, using McGrath’s responses, examine whether the use of foetal imagery in anti-abortion campaigns is a legitimate instance of this practice.
- Full Text:
- Date Issued: 2015
‘… a huge monster that should be feared and not done’: lessons learned in sexuality education classes in South Africa
- Shefer, Tamara, Kruger, Lou-Marie, Macleod, Catriona I, Baxen, Jean, Vincent, Louise
- Authors: Shefer, Tamara , Kruger, Lou-Marie , Macleod, Catriona I , Baxen, Jean , Vincent, Louise
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6314 , http://hdl.handle.net/10962/d1020933 , http://www.mrc.ac.za/crime/aspj/2015/AhugeMonster.pdf
- Description: Research has foregrounded the way in which heterosexual practices for many young people are not infrequently bound up with violence and unequal transactional power relations. The Life Orientation sexuality education curriculum in South African schools has been viewed as a potentially valuable space to work with young people on issues of reproductive health, gender and sexual norms and relations. Yet, research has illustrated that such work may not only be failing to impact on more equitable sexual practices between young men and women, but may also serve to reproduce the very discourses and practices that the work aims to challenge. Cultures of violence in youth sexuality are closely connected to prevailing gender norms and practices which, for example, render women as passive victims who are incapable of exercising sexual agency and men as inherently sexually predatory. This paper analyses the talk of Grade 10 learners in nine diverse schools in two South African provinces, the Eastern Cape and the Western Cape, to highlight what ‘lessons’ these young people seem to be learning about sexuality in Life Orientation classes. We find that these lessons foreground cautionary, negative and punitive messages, which reinforce, rather than challenge, normative gender roles. ‘Scare’ messages of danger, damage and disease give rise to presumptions of gendered responsibility for risk and the requirement of female restraint in the face of the assertion of masculine desire and predation. We conclude that the role which sexuality education could play in enabling young women in particular to more successfully negotiate their sexual relationships to serve their own needs, reproductive health and safety, is undermined by regulatory messages directed at controlling young people, and young women in particular – and that instead, young people’s sexual agency has to be acknowledged in any processes of change aimed at gender equality, anti-violence, health and well-being.
- Full Text:
- Date Issued: 2015
- Authors: Shefer, Tamara , Kruger, Lou-Marie , Macleod, Catriona I , Baxen, Jean , Vincent, Louise
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6314 , http://hdl.handle.net/10962/d1020933 , http://www.mrc.ac.za/crime/aspj/2015/AhugeMonster.pdf
- Description: Research has foregrounded the way in which heterosexual practices for many young people are not infrequently bound up with violence and unequal transactional power relations. The Life Orientation sexuality education curriculum in South African schools has been viewed as a potentially valuable space to work with young people on issues of reproductive health, gender and sexual norms and relations. Yet, research has illustrated that such work may not only be failing to impact on more equitable sexual practices between young men and women, but may also serve to reproduce the very discourses and practices that the work aims to challenge. Cultures of violence in youth sexuality are closely connected to prevailing gender norms and practices which, for example, render women as passive victims who are incapable of exercising sexual agency and men as inherently sexually predatory. This paper analyses the talk of Grade 10 learners in nine diverse schools in two South African provinces, the Eastern Cape and the Western Cape, to highlight what ‘lessons’ these young people seem to be learning about sexuality in Life Orientation classes. We find that these lessons foreground cautionary, negative and punitive messages, which reinforce, rather than challenge, normative gender roles. ‘Scare’ messages of danger, damage and disease give rise to presumptions of gendered responsibility for risk and the requirement of female restraint in the face of the assertion of masculine desire and predation. We conclude that the role which sexuality education could play in enabling young women in particular to more successfully negotiate their sexual relationships to serve their own needs, reproductive health and safety, is undermined by regulatory messages directed at controlling young people, and young women in particular – and that instead, young people’s sexual agency has to be acknowledged in any processes of change aimed at gender equality, anti-violence, health and well-being.
- Full Text:
- Date Issued: 2015
“Peer pressure” and “Peer normalization” : discursive resources that justify gendered youth sexualities
- Macleod, Catriona I, Jearey-Graham, Nicola
- Authors: Macleod, Catriona I , Jearey-Graham, Nicola
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6312 , http://hdl.handle.net/10962/d1019877 , https://link.springer.com/article/10.1007/s13178-015-0207-8
- Description: “Peer pressure” is associated in the scientific literature with a range of risky sexual behaviors and with undermining public sexual health messages. Interventions are instituted encouraging young people to resist peer pressure or to model positive peer norms. Taking a discursive psychology perspective, we show how young people themselves use the discourses of “peer pressure to have sex” and “peer normalization of sex” to explain and justify youth sexual activity. Using data from focus group discussions about youth sexualities with students at a South African further education and training college, we show how participants outlined a need for young people to be socially recognizable through engaging in, and talking about, sex and how they implicated peer norms in governing individual sexual behavior. Both discourses pointed to a gendering of peer-endorsed sexual norms: masculine virility, the avoidance of shameful virgin or gay positions, and multiple sexual partners were emphasized for men, while the necessity of keeping a boyfriend and avoiding a “slut” position were foregrounded for women. These discourses potentially undermine the aims of public sexual health programs targeting youth. Nuanced engagement with peer group narratives, especially how sexual activity is explained and justified in a gendered fashion, is indicated. , Full text access on Publisher website: https://link.springer.com/article/10.1007/s13178-015-0207-8
- Full Text: false
- Date Issued: 2015
- Authors: Macleod, Catriona I , Jearey-Graham, Nicola
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:6312 , http://hdl.handle.net/10962/d1019877 , https://link.springer.com/article/10.1007/s13178-015-0207-8
- Description: “Peer pressure” is associated in the scientific literature with a range of risky sexual behaviors and with undermining public sexual health messages. Interventions are instituted encouraging young people to resist peer pressure or to model positive peer norms. Taking a discursive psychology perspective, we show how young people themselves use the discourses of “peer pressure to have sex” and “peer normalization of sex” to explain and justify youth sexual activity. Using data from focus group discussions about youth sexualities with students at a South African further education and training college, we show how participants outlined a need for young people to be socially recognizable through engaging in, and talking about, sex and how they implicated peer norms in governing individual sexual behavior. Both discourses pointed to a gendering of peer-endorsed sexual norms: masculine virility, the avoidance of shameful virgin or gay positions, and multiple sexual partners were emphasized for men, while the necessity of keeping a boyfriend and avoiding a “slut” position were foregrounded for women. These discourses potentially undermine the aims of public sexual health programs targeting youth. Nuanced engagement with peer group narratives, especially how sexual activity is explained and justified in a gendered fashion, is indicated. , Full text access on Publisher website: https://link.springer.com/article/10.1007/s13178-015-0207-8
- Full Text: false
- Date Issued: 2015
(Ferrocenylpyrazolyl)zinc(II) benzoates as catalysts for the ring opening polymerization of ε-caprolactone
- Obuah, Collins, Lochee, Yemanlall, Jordaan, Johan H L, Otto, Daniel P, Nyokong, Tebello, Darkwa, James
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Language: English
- Type: Article
- Identifier: vital:7264 , http://hdl.handle.net/10962/d1020273
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of ɛ-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol−1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 × 10−7 h−1 mol−1 at 110 °C. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.02.007
- Full Text: false
- Authors: Obuah, Collins , Lochee, Yemanlall , Jordaan, Johan H L , Otto, Daniel P , Nyokong, Tebello , Darkwa, James
- Language: English
- Type: Article
- Identifier: vital:7264 , http://hdl.handle.net/10962/d1020273
- Description: The reaction of Zn(OAc)2 and C6H5COOH or 3,5-NO2-C6H3COOH with 3-ferrocenylpyrazolyl-methylenepyridine (L1), 3-ferrocenyl-5-methylpyrazolyl-methylenepyridine (L2), 3-ferrocenylpyrazolyl-ethylamine (L3) and 3-ferrocenyl-5-pyrazolyl-ethylamine (L4) afford the corresponding complexes [Zn(C6H5COO)2(L1)] (1), [Zn(C6H5COO)2(L2)] (2), [Zn(3,5-NO2-C6H3COO)2(L1)] (3), [Zn(3,5-NO2-C6H3COO)2(L2)] (4), [Zn(C6H5COO)2(L3)] (5), [Zn(C6H5COO)2(L4)] (6), [Zn(3,5-NO2-C6H3COO)2(L3)] (7) and [Zn(3,5-NO2-C6H3COO)2(L4)] (8). These complexes behave as catalysts for the ring opening polymerization of ɛ-caprolactone to produce polymers with molecular weight that range from 1480 to 7080 g mol−1 and exhibited moderate to broad PDIs. Evidence of these complexes acting as catalysts was obtained from both the polymerization data and kinetic studies. The polymerization data show that variation of the [CL]/[C] from 100 to 800 produced PCL with relatively the same molecular weight indicative of a catalyst behavior. The appearance of induction period in kinetic plots strengthens the fact that these complexes are catalysts rather than initiators. MALDI-TOF MS and 1H NMR data show di-hydroxy end groups, which support the coordination mechanism rather than insertion mechanism. To understand the broad PDIs obtained for some of the polymer, the electronic properties of the zinc complexes were investigated using cyclic voltammetry. The results show that the zinc complexes containing amine based ligands are highly electrophilic therefore making them unstable, hence the broad PDIs observed for zinc complexes containing amine based ligands. Among the eight complexes investigated, complex 7 is the most active catalyst with kp value of 1.18 × 10−7 h−1 mol−1 at 110 °C. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.02.007
- Full Text: false
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7285 , http://hdl.handle.net/10962/d1020332
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards l-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.05.038
- Full Text: false
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7285 , http://hdl.handle.net/10962/d1020332
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards l-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.05.038
- Full Text: false
Effects of Redox Mediators on the Catalytic Activity of Iron Porphyrins towards Oxygen Reduction in Acidic Media
- He, Qinggang, Wu, Gang, Liu, Ke, Khene, M Samson, Li, Qing, Mugadza, Tawanda, Deunf, Elise, Nyokong, Tebello, Chen, Shaowei W
- Authors: He, Qinggang , Wu, Gang , Liu, Ke , Khene, M Samson , Li, Qing , Mugadza, Tawanda , Deunf, Elise , Nyokong, Tebello , Chen, Shaowei W
- Language: English
- Type: Article
- Identifier: vital:7291 , http://hdl.handle.net/10962/d1020354
- 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. , Original publication is available at http://dx.doi.org/10.1002/celc.201402054
- Full Text: false
- Authors: He, Qinggang , Wu, Gang , Liu, Ke , Khene, M Samson , Li, Qing , Mugadza, Tawanda , Deunf, Elise , Nyokong, Tebello , Chen, Shaowei W
- Language: English
- Type: Article
- Identifier: vital:7291 , http://hdl.handle.net/10962/d1020354
- 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. , Original publication is available at http://dx.doi.org/10.1002/celc.201402054
- Full Text: false