Spectral properties and photophysical behaviour of water soluble cationic Mg (II) and Al (III) phthalocyanines
- Idowu, Mopelola A, Arslanoğlu, Yasin, Nyokong, Tebello
- Authors: Idowu, Mopelola A , Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241549 , vital:50949 , xlink:href="https://doi.org/10.2478/s11532-013-0388-z"
- Description: Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA).
- Full Text:
- Date Issued: 2014
- Authors: Idowu, Mopelola A , Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241549 , vital:50949 , xlink:href="https://doi.org/10.2478/s11532-013-0388-z"
- Description: Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA).
- 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
An Interview with Ken Barris:
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144050 , vital:38306 , DOI: 10.4314/eia.v41i1.9
- Description: Ken Barris was born in Port Elizabeth and lives in Cape Town, where he works at the Cape Peninsula University of Technology. His writing includes two collections of poetry, a collection of short stories, and five novels, the most recent being What Kind of Child (2006) and Life Underwater (2012). His work has been translated into Turkish, Danish, German and Slovenian, and poetry and short fiction have appeared in various anthologies. More recently, he has turned to writing for academic journals. His research interests are postapartheid fiction and language education.
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144050 , vital:38306 , DOI: 10.4314/eia.v41i1.9
- Description: Ken Barris was born in Port Elizabeth and lives in Cape Town, where he works at the Cape Peninsula University of Technology. His writing includes two collections of poetry, a collection of short stories, and five novels, the most recent being What Kind of Child (2006) and Life Underwater (2012). His work has been translated into Turkish, Danish, German and Slovenian, and poetry and short fiction have appeared in various anthologies. More recently, he has turned to writing for academic journals. His research interests are postapartheid fiction and language education.
- Full Text:
- Date Issued: 2014
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189898 , vital:44945 , xlink:href="https://doi.org/10.1016/j.dyepig.2014.05.010"
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli.
- Full Text:
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189898 , vital:44945 , xlink:href="https://doi.org/10.1016/j.dyepig.2014.05.010"
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli.
- Full Text:
- Date Issued: 2014
Critical realist versus mainstream interdisciplinarity
- Authors: Price, Leigh
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391143 , vital:68624 , xlink:href="https://doi.org/10.1179/1476743013Z.00000000019"
- Description: In this paper I argue for the superiority of a critical realist understanding of interdisciplinarity over a mainstream understanding of it. I begin by exploring the reasons for the failure of mainstream researchers to achieve interdisciplinarity. My main argument is that mainstream interdisciplinary researchers tend to hypostatize facts, fetishize constant conjunctions of events and apply to open systems an epistemology designed for closed systems. I also explain how mainstream interdisciplinarity supports oppression and gross inequality. I argue that mainstream interdisciplinarity is not true interdisciplinarity and refer to it accordingly as ‘condisciplinarity’. By way of example, I examine the condisciplinarity of the World Health Organization’s ecological model applied to the issue of men’s violence against women. Specifically, I argue that critical realist interdisciplinarity is preferable because it acknowledges inter alia the empirical, actual and real layers of reality, which allows it to develop depth-explanations of phenomena. In practice, this means that critical realist interdisciplinarity can potentially provide explanations that, compared to condisciplinarity, are broader (include more of the human and non-human context) and deeper (include for example individuals’ conscious and unconscious psychological motivations). In the World Health Organization’s example of the causes of men’s violence against women, condisciplinarity resulted in the absence of historical, global and unconscious aspects of the problem. It is also restricted the analysis to reductive, constant-conjunction based theories of the causes of the problem, specifically ‘risk factors’, thereby providing a relatively shallow explanation for the problem.
- Full Text:
- Date Issued: 2014
- Authors: Price, Leigh
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391143 , vital:68624 , xlink:href="https://doi.org/10.1179/1476743013Z.00000000019"
- Description: In this paper I argue for the superiority of a critical realist understanding of interdisciplinarity over a mainstream understanding of it. I begin by exploring the reasons for the failure of mainstream researchers to achieve interdisciplinarity. My main argument is that mainstream interdisciplinary researchers tend to hypostatize facts, fetishize constant conjunctions of events and apply to open systems an epistemology designed for closed systems. I also explain how mainstream interdisciplinarity supports oppression and gross inequality. I argue that mainstream interdisciplinarity is not true interdisciplinarity and refer to it accordingly as ‘condisciplinarity’. By way of example, I examine the condisciplinarity of the World Health Organization’s ecological model applied to the issue of men’s violence against women. Specifically, I argue that critical realist interdisciplinarity is preferable because it acknowledges inter alia the empirical, actual and real layers of reality, which allows it to develop depth-explanations of phenomena. In practice, this means that critical realist interdisciplinarity can potentially provide explanations that, compared to condisciplinarity, are broader (include more of the human and non-human context) and deeper (include for example individuals’ conscious and unconscious psychological motivations). In the World Health Organization’s example of the causes of men’s violence against women, condisciplinarity resulted in the absence of historical, global and unconscious aspects of the problem. It is also restricted the analysis to reductive, constant-conjunction based theories of the causes of the problem, specifically ‘risk factors’, thereby providing a relatively shallow explanation for the problem.
- Full Text:
- Date Issued: 2014
Zimbabwe takes back its land:
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144677 , vital:38369 , DOI: 10.1080/02589001.2014.984946
- Description: Zimbabwe Takes Back its Land offers a useful introduction to fast-track land reform in contemporary Zimbabwe for a broad popular audience unfamiliar with the existing literature on fast-track land reform. But its value as a contribution to a more specialised and nuanced body of knowledge about fast-track is considerably more problematic.
- Full Text:
- Date Issued: 2014
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144677 , vital:38369 , DOI: 10.1080/02589001.2014.984946
- Description: Zimbabwe Takes Back its Land offers a useful introduction to fast-track land reform in contemporary Zimbabwe for a broad popular audience unfamiliar with the existing literature on fast-track land reform. But its value as a contribution to a more specialised and nuanced body of knowledge about fast-track is considerably more problematic.
- Full Text:
- Date Issued: 2014
Synthesis of ytterbium bisphthalocyanines
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189887 , vital:44943 , xlink:href="https://doi.org/10.1016/j.optmat.2014.05.013"
- Description: Herein we report on the syntheses, photophysico-chemical properties and nonlinear absorption parameters of bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) (3) and bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). The fluorescence and singlet oxygen quantum yields obtained for complexes 3 and 4 are low. The triplet quantum yield obtained for complex 3 is high at ΦT = 0.89 whereas for complex 4 ΦT = 0.48. The third order optical susceptibility values are of the order: 10−11 esu (for complex 3), and 10−13 esu (for complex 4) while the hyperpolarizability values are of the order: 10−28 esu (for complex 3) and 10−31 esu (for complex 4). Complexes 3 and 4 show two-photon absorption coefficients of the order of 10−46 cm4 s/photon and 10−48 cm4 s/photon, and threshold intensities as low as 0.3 J cm−2 and 0.0045 J cm−2, respectively.
- Full Text:
- Date Issued: 2014
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189887 , vital:44943 , xlink:href="https://doi.org/10.1016/j.optmat.2014.05.013"
- Description: Herein we report on the syntheses, photophysico-chemical properties and nonlinear absorption parameters of bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) (3) and bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). The fluorescence and singlet oxygen quantum yields obtained for complexes 3 and 4 are low. The triplet quantum yield obtained for complex 3 is high at ΦT = 0.89 whereas for complex 4 ΦT = 0.48. The third order optical susceptibility values are of the order: 10−11 esu (for complex 3), and 10−13 esu (for complex 4) while the hyperpolarizability values are of the order: 10−28 esu (for complex 3) and 10−31 esu (for complex 4). Complexes 3 and 4 show two-photon absorption coefficients of the order of 10−46 cm4 s/photon and 10−48 cm4 s/photon, and threshold intensities as low as 0.3 J cm−2 and 0.0045 J cm−2, respectively.
- Full Text:
- Date Issued: 2014
Apprehension of bias and the spectacle of the fair-minded observer: a survey of recent commonwealth and South African decisions on pre-judgment
- Okpaluba, Chuks, Juma, Laurence
- Authors: Okpaluba, Chuks , Juma, Laurence
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126107 , vital:35850 , http://specjuris.ufh.ac.za/apprehension-bias-and-spectacle-fair-minded-observer-survey-recent-commonwealth-and-south-african
- Description: A perusal of contemporary Commonwealth case law reveals that allegations of bias or apprehension of bias tend to revolve around the pecuniary or other interests of the Judge arising from kinship, previous relationship, or association with party or counsel.1Apparent bias could also be inferred from the judge‘s conduct or utterances, especially, his/her criticisms or cumulative criticisms of a party during proceedings or in adjudication.2In other instances, a judge‘s previous knowledge or association with the case in court, or of an important witness, may disqualify him/her from sitting or passing judgment in the case.3
- Full Text:
- Date Issued: 2014
- Authors: Okpaluba, Chuks , Juma, Laurence
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126107 , vital:35850 , http://specjuris.ufh.ac.za/apprehension-bias-and-spectacle-fair-minded-observer-survey-recent-commonwealth-and-south-african
- Description: A perusal of contemporary Commonwealth case law reveals that allegations of bias or apprehension of bias tend to revolve around the pecuniary or other interests of the Judge arising from kinship, previous relationship, or association with party or counsel.1Apparent bias could also be inferred from the judge‘s conduct or utterances, especially, his/her criticisms or cumulative criticisms of a party during proceedings or in adjudication.2In other instances, a judge‘s previous knowledge or association with the case in court, or of an important witness, may disqualify him/her from sitting or passing judgment in the case.3
- Full Text:
- Date Issued: 2014
Indium phthalocyanine–CdSe/ZnS quantum dots nanocomposites showing size dependent and near ideal optical limiting behaviour
- 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/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- 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/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- Full Text:
- Date Issued: 2014
Liberation movements in power: party and state in southern Africa
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144688 , vital:38370 , DOI: 10.1080/21528586.2014.960705
- Description: In Liberation movements in power, Roger Southall provides a rich and refined account of political transformation in three ex-settler colonies in southern Africa, namely, South Africa, Namibia and Zimbabwe. In particular, he focuses on their former hegemonic national liberation movements, namely, the African National Congress (ANC) in South Africa, the South West African People’s Organisation (SWAPO) in Namibia and the Zimbabwe African National Union (ZANU) – now ZANU-Patriotic Front (ZANU-PF) – in Zimbabwe, their metamorphism into political parties and party machines, and their ‘capture’ of state power as the dominant political party subsequent to the end of white settler colonialism and the emergence of non-racial democracy. The general conclusion is that democratic ideals and procedures have become subordinated to the dictates of authoritarian restructuring.
- Full Text:
- Date Issued: 2014
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144688 , vital:38370 , DOI: 10.1080/21528586.2014.960705
- Description: In Liberation movements in power, Roger Southall provides a rich and refined account of political transformation in three ex-settler colonies in southern Africa, namely, South Africa, Namibia and Zimbabwe. In particular, he focuses on their former hegemonic national liberation movements, namely, the African National Congress (ANC) in South Africa, the South West African People’s Organisation (SWAPO) in Namibia and the Zimbabwe African National Union (ZANU) – now ZANU-Patriotic Front (ZANU-PF) – in Zimbabwe, their metamorphism into political parties and party machines, and their ‘capture’ of state power as the dominant political party subsequent to the end of white settler colonialism and the emergence of non-racial democracy. The general conclusion is that democratic ideals and procedures have become subordinated to the dictates of authoritarian restructuring.
- Full Text:
- Date Issued: 2014
Enhanced Optical Limiting Behavior of an Indium Phthalocyanine–Single-Walled Carbon Nanotube Composite
- Sanusi, Kayode, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Sanusi, Kayode , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193871 , vital:45401 , xlink:href="https://doi.org/10.1021/jp501469e "
- Description: The nonlinear optical behavior of 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (2) and its carbon nanotube composite in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions is described. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. A large nonlinear absorption that increased on covalent linking with single-walled carbon nanotubes (SWCNTs) was observed for the compound in DMSO. The nanosecond nonlinear absorption and the optical limiting behavior of this complex are shown to be dominated by a strong excited state absorption from a two-photon pumped state. The optical limiter using the new nanocomposite material (SWCNT-2) in the appropriate solvent showed a much lower threshold for optical limiting together with a much lower transmission at high fluences than previously reported nanocomposite limiters. The optical properties of the phthalocyanine and its conjugate were found to show high sensitivity toward the change of solvent matrix.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193871 , vital:45401 , xlink:href="https://doi.org/10.1021/jp501469e "
- Description: The nonlinear optical behavior of 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (2) and its carbon nanotube composite in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions is described. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. A large nonlinear absorption that increased on covalent linking with single-walled carbon nanotubes (SWCNTs) was observed for the compound in DMSO. The nanosecond nonlinear absorption and the optical limiting behavior of this complex are shown to be dominated by a strong excited state absorption from a two-photon pumped state. The optical limiter using the new nanocomposite material (SWCNT-2) in the appropriate solvent showed a much lower threshold for optical limiting together with a much lower transmission at high fluences than previously reported nanocomposite limiters. The optical properties of the phthalocyanine and its conjugate were found to show high sensitivity toward the change of solvent matrix.
- Full Text:
- Date Issued: 2014
Ordinary people and the media: the demotic turn
- Authors: Garman, Anthea
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159880 , vital:40352 , DOI: 10.1080/02560054.2014.886661
- Description: In this latest book, Graeme Turner, who we have come to know as a thoughtful, perceptive and questioning cultural studies theorist, investigates what the crucial underlying shift is in the relation between the media and the people. This shift is evidenced by the increasing visibility of ordinary people (and their experiences and opinions) in what we consume. At the outset he sums up what he sees as a structural move from media as ‘mediator or perhaps a broadcaster of cultural identities’ to ‘translator or even an author of identities’ (p. 3).
- Full Text:
- Date Issued: 2014
- Authors: Garman, Anthea
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159880 , vital:40352 , DOI: 10.1080/02560054.2014.886661
- Description: In this latest book, Graeme Turner, who we have come to know as a thoughtful, perceptive and questioning cultural studies theorist, investigates what the crucial underlying shift is in the relation between the media and the people. This shift is evidenced by the increasing visibility of ordinary people (and their experiences and opinions) in what we consume. At the outset he sums up what he sees as a structural move from media as ‘mediator or perhaps a broadcaster of cultural identities’ to ‘translator or even an author of identities’ (p. 3).
- Full Text:
- Date Issued: 2014
Cosmological efficacy and the politics of Sacred Place: Soli Rainmaking in contemporary Zambia
- Authors: Simbao, Ruth K
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147482 , vital:38642 , https://doi.org/10.1162/AFAR_a_00163
- Description: In this article I analyze cosmological efficacy in light of the politicization and apparent secularization of contemporary annual ceremonies in Zambia, south-central Africa, which are framed by scholars as neotraditional (Lentz 2001), folklorized (van Binsbergen 1994), or retraditionalized (Gould 2005:3, 6) events. My term “festivalization” registers the formalization of Zambian performances such as rituals, harvest festivals, inaugurations, and initiations as annual festival events, but does not imply a pejorative attitude towards cultural change and so-called inauthenticity, as the words “folklorization” or “retraditionalization” seem to do.
- Full Text:
- Date Issued: 2014
- Authors: Simbao, Ruth K
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147482 , vital:38642 , https://doi.org/10.1162/AFAR_a_00163
- Description: In this article I analyze cosmological efficacy in light of the politicization and apparent secularization of contemporary annual ceremonies in Zambia, south-central Africa, which are framed by scholars as neotraditional (Lentz 2001), folklorized (van Binsbergen 1994), or retraditionalized (Gould 2005:3, 6) events. My term “festivalization” registers the formalization of Zambian performances such as rituals, harvest festivals, inaugurations, and initiations as annual festival events, but does not imply a pejorative attitude towards cultural change and so-called inauthenticity, as the words “folklorization” or “retraditionalization” seem to do.
- Full Text:
- Date Issued: 2014
Rise and fall of apartheid: photography and the bureaucracy of everyday life
- Authors: Simbao, Ruth K
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147604 , vital:38653 , DOI: 10.1080/02533952.2014.998052
- Description: The exhibition catalogue Rise and Fall of Apartheid is a valuable collection of photographic images that create, according to Enwezor, “a critical visualization and interrogation of […] [apartheid’s] normative symbols, signs and representation” (18). The catalogue focuses on African subjects as “agents of their own emancipation” (18), and contextualises South Africa’s anticipation of the end of apartheid within broader global changes in the late 1980s. Essays by Okwui Enwezor, Michael Godby, Achille Mbembe, Darren Newbury, Colin Richards, Patricia Hayes, Andries Walter Olifant, Rory Bester and Khwezi Gule are included in the catalogue, and are interspersed between photographic images that are grouped in chronological clusters: 1948–1959; 1960–1969; 1970–1979; 1980–1989; and 1990–1995.
- Full Text:
- Date Issued: 2014
- Authors: Simbao, Ruth K
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147604 , vital:38653 , DOI: 10.1080/02533952.2014.998052
- Description: The exhibition catalogue Rise and Fall of Apartheid is a valuable collection of photographic images that create, according to Enwezor, “a critical visualization and interrogation of […] [apartheid’s] normative symbols, signs and representation” (18). The catalogue focuses on African subjects as “agents of their own emancipation” (18), and contextualises South Africa’s anticipation of the end of apartheid within broader global changes in the late 1980s. Essays by Okwui Enwezor, Michael Godby, Achille Mbembe, Darren Newbury, Colin Richards, Patricia Hayes, Andries Walter Olifant, Rory Bester and Khwezi Gule are included in the catalogue, and are interspersed between photographic images that are grouped in chronological clusters: 1948–1959; 1960–1969; 1970–1979; 1980–1989; and 1990–1995.
- Full Text:
- Date Issued: 2014
Reappraising the concept of biocultural diversity: a perspective from South Africa
- Cocks, Michelle L, Wiersum, K Freerk
- Authors: Cocks, Michelle L , Wiersum, K Freerk
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141176 , vital:37950 , DOI: 10.1007/s10745-014-9681-5
- Description: Biocultural diversity has been conceptualised as the sum of the world’s differences regarding biological diversity at all levels and cultural diversity in all its manifestations, and their interactions. The concept is often framed in the context of conservation as a retention versus loss model by emphasizing the religious and spiritual values of the natural environment and the positive interactions between traditional indigenous people and conservation of natural ecosystems and indigenous species. On the basis of our research amongst the ‘non-traditional’ amaXhosa in South Africa, we argue that this interpretation is too narrow and that the concept needs to be reappraised in order to capture the dynamic, complex and relational nature of bio-cultural diversity relations. We conclude that the concept involves a complex of human values and practices related to the three main dimensions of biodiversity at landscapes, species and genetic levels.
- Full Text:
- Date Issued: 2014
- Authors: Cocks, Michelle L , Wiersum, K Freerk
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141176 , vital:37950 , DOI: 10.1007/s10745-014-9681-5
- Description: Biocultural diversity has been conceptualised as the sum of the world’s differences regarding biological diversity at all levels and cultural diversity in all its manifestations, and their interactions. The concept is often framed in the context of conservation as a retention versus loss model by emphasizing the religious and spiritual values of the natural environment and the positive interactions between traditional indigenous people and conservation of natural ecosystems and indigenous species. On the basis of our research amongst the ‘non-traditional’ amaXhosa in South Africa, we argue that this interpretation is too narrow and that the concept needs to be reappraised in order to capture the dynamic, complex and relational nature of bio-cultural diversity relations. We conclude that the concept involves a complex of human values and practices related to the three main dimensions of biodiversity at landscapes, species and genetic levels.
- Full Text:
- Date Issued: 2014
Contextualising Curriculum Design and Recontextualising Its Implementation: The Case of Climate Change Education for Southern African Transfrontier Conservation Area Practitioners
- Mukute, Mutizwa, Pesanayi, Tichaona V
- Authors: Mukute, Mutizwa , Pesanayi, Tichaona V
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387173 , vital:68212 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/121965"
- Description: This paper discusses how the climate change education needs of park managers, ecologists, and community development officers in Southern African Development Community (SADC) Transfrontier Conservation Areas (TFCAs) were established through contextual profiling. It subsequently analyses how a curriculum that was designed in response to a contextual profiling process was recontextualised during implementation by the SADC Regional Environmental Education Programme (REEP), with support from German Federal Enterprise for International Cooperation (GIZ). The paper’s purpose is to trace the trajectory of contextualised curriculum development and implementation with a view to identifying how the twin concepts of contextual profiling and recontextualisation were utilised and lessons were learnt. The paper has potential value for educators/trainers interested in increasing the relevance of protected area workplace learning and its congruence to learners’ realities.
- Full Text:
- Date Issued: 2014
- Authors: Mukute, Mutizwa , Pesanayi, Tichaona V
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387173 , vital:68212 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/121965"
- Description: This paper discusses how the climate change education needs of park managers, ecologists, and community development officers in Southern African Development Community (SADC) Transfrontier Conservation Areas (TFCAs) were established through contextual profiling. It subsequently analyses how a curriculum that was designed in response to a contextual profiling process was recontextualised during implementation by the SADC Regional Environmental Education Programme (REEP), with support from German Federal Enterprise for International Cooperation (GIZ). The paper’s purpose is to trace the trajectory of contextualised curriculum development and implementation with a view to identifying how the twin concepts of contextual profiling and recontextualisation were utilised and lessons were learnt. The paper has potential value for educators/trainers interested in increasing the relevance of protected area workplace learning and its congruence to learners’ realities.
- Full Text:
- Date Issued: 2014
Synthesis and characterization of quantum dots designed for biomedical use
- Kuzyniak, Weronika, Adegoke, Oluwasesan, Sekhosana, Kutloana E, D'Souza, Sarah, Tshangana, Sesethu Charmaine, Hoffmann, Björn, Ermilov, Eugeny A, Nyokong, Tebello, Höpfner, Michael
- Authors: Kuzyniak, Weronika , Adegoke, Oluwasesan , Sekhosana, Kutloana E , D'Souza, Sarah , Tshangana, Sesethu Charmaine , Hoffmann, Björn , Ermilov, Eugeny A , Nyokong, Tebello , Höpfner, Michael
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241516 , vital:50946 , xlink:href="https://doi.org/10.1016/j.ijpharm.2014.03.037"
- Description: Semiconductor quantum dots (QDs) have become promising nanoparticles for a wide variety of biomedical applications. However, the major drawback of QDs is their potential toxicity. Here, we determined possible cytotoxic effects of a set of QDs by systematic photophysical evaluation in vitro as well as in vivo. QDs were synthesized by the hydrothermal aqueous route with sizes in the range of 2.0–3.5 nm. Cytotoxic effects of QDs were studied in the human pancreatic carcinoid cell line BON. Cadmium telluride QDs with or without zinc sulfide shell and coated with 3-mercaptopropionic acid (MPA) were highly cytotoxic even at nanomolar concentrations. Capping with L-glutathione (GSH) or thioglycolic acid (TGA) reduced the cytotoxicity of cadmium telluride QDs and cadmium selenide QDs. Determination of the toxicity of QDs revealed IC50 values in the micromolar range. In vivo studies showed good tolerability of CdSe QDs with ZnS shell and GSH capping. We could demonstrate that QDs with ZnS shell and GSH capping exhibit low toxicity and good tolerability in cell models and living organisms. These QDs appear to be promising candidates for biomedical applications such as drug delivery for enhanced chemotherapy or targeted delivery of light sensitive substances for photodynamic therapy.
- Full Text:
- Date Issued: 2014
- Authors: Kuzyniak, Weronika , Adegoke, Oluwasesan , Sekhosana, Kutloana E , D'Souza, Sarah , Tshangana, Sesethu Charmaine , Hoffmann, Björn , Ermilov, Eugeny A , Nyokong, Tebello , Höpfner, Michael
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241516 , vital:50946 , xlink:href="https://doi.org/10.1016/j.ijpharm.2014.03.037"
- Description: Semiconductor quantum dots (QDs) have become promising nanoparticles for a wide variety of biomedical applications. However, the major drawback of QDs is their potential toxicity. Here, we determined possible cytotoxic effects of a set of QDs by systematic photophysical evaluation in vitro as well as in vivo. QDs were synthesized by the hydrothermal aqueous route with sizes in the range of 2.0–3.5 nm. Cytotoxic effects of QDs were studied in the human pancreatic carcinoid cell line BON. Cadmium telluride QDs with or without zinc sulfide shell and coated with 3-mercaptopropionic acid (MPA) were highly cytotoxic even at nanomolar concentrations. Capping with L-glutathione (GSH) or thioglycolic acid (TGA) reduced the cytotoxicity of cadmium telluride QDs and cadmium selenide QDs. Determination of the toxicity of QDs revealed IC50 values in the micromolar range. In vivo studies showed good tolerability of CdSe QDs with ZnS shell and GSH capping. We could demonstrate that QDs with ZnS shell and GSH capping exhibit low toxicity and good tolerability in cell models and living organisms. These QDs appear to be promising candidates for biomedical applications such as drug delivery for enhanced chemotherapy or targeted delivery of light sensitive substances for photodynamic therapy.
- Full Text:
- Date Issued: 2014
Behavior of palladium nanoparticles in the absence or presence of cobalt tetraaminophthalocyanine for the electrooxidation of hydrazine
- Maringa, Audacity, Nyokong, Tebello
- Authors: Maringa, Audacity , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189796 , vital:44932 , xlink:href="https://doi.org/10.1002/elan.201400028"
- Description: We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly-CoTAPc-GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs-GCE and PdNPs/poly-CoTAPc-GCE, respectively. PdNPs/poly-CoTAPc-GCE showed the best activity for the oxidation of hydrazine at the lowest potential of −0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly-CoTAPc-GCE compared to PdNPs-GCE. The catalytic rate constant for hydrazine oxidation was 6.12×108 cm3 mol−1 s−1 using PdNPs/poly-CoTAPc-GCE.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189796 , vital:44932 , xlink:href="https://doi.org/10.1002/elan.201400028"
- Description: We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly-CoTAPc-GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs-GCE and PdNPs/poly-CoTAPc-GCE, respectively. PdNPs/poly-CoTAPc-GCE showed the best activity for the oxidation of hydrazine at the lowest potential of −0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly-CoTAPc-GCE compared to PdNPs-GCE. The catalytic rate constant for hydrazine oxidation was 6.12×108 cm3 mol−1 s−1 using PdNPs/poly-CoTAPc-GCE.
- Full Text:
- Date Issued: 2014
Thinking Africa Newsletter: (June 2014)
- Authors: Matthews, Sally
- Date: 2014
- Language: English
- Type: text , article
- Identifier: vital:38065 , http://hdl.handle.net/20.500.12137/23
- Description: Thinking Africa Newsletter (June 2014).
- Full Text:
- Date Issued: 2014
- Authors: Matthews, Sally
- Date: 2014
- Language: English
- Type: text , article
- Identifier: vital:38065 , http://hdl.handle.net/20.500.12137/23
- Description: Thinking Africa Newsletter (June 2014).
- Full Text:
- Date Issued: 2014
The incurious seeker: waiting, and the search for the stranger in the fiction of Samuel Beckett and JM Coetzee
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143971 , vital:38299 , https://mediatropes.com/index.php/Mediatropes/article/view/22380/18161
- Description: In J.M. Coetzee and the Novel: Writing and Politics after Beckett, Patrick Hayes argues that Coetzee, while influenced by Beckett’s prose style, assimilates it in such a way that his writing not only departs from the latter’s solipsism but also provides “an anti-foundational imagining of moral community” (71). While there is much merit to this argument, Hayes’s distinction between Beckett’s solipsism and Coetzee’s concern with community downplays the extent to which the human subject’s conception of herself depends on the differential process through which community establishes itself. In the first section of this paper I show that, already in Murphy, we find evidence in support of Ileana Marculescu’s argument that Beckett inscribes solipsism in his writing only to subvert it. Murphy’s attempts at solipsistic knowledge fail precisely because he has been estranged from himself by language and community. What appears to be solipsism is, in fact, a search for the self from which he has been divided by community. In Beckett’s writing, the self’s concern with its ability to know itself is always a concern with community.
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143971 , vital:38299 , https://mediatropes.com/index.php/Mediatropes/article/view/22380/18161
- Description: In J.M. Coetzee and the Novel: Writing and Politics after Beckett, Patrick Hayes argues that Coetzee, while influenced by Beckett’s prose style, assimilates it in such a way that his writing not only departs from the latter’s solipsism but also provides “an anti-foundational imagining of moral community” (71). While there is much merit to this argument, Hayes’s distinction between Beckett’s solipsism and Coetzee’s concern with community downplays the extent to which the human subject’s conception of herself depends on the differential process through which community establishes itself. In the first section of this paper I show that, already in Murphy, we find evidence in support of Ileana Marculescu’s argument that Beckett inscribes solipsism in his writing only to subvert it. Murphy’s attempts at solipsistic knowledge fail precisely because he has been estranged from himself by language and community. What appears to be solipsism is, in fact, a search for the self from which he has been divided by community. In Beckett’s writing, the self’s concern with its ability to know itself is always a concern with community.
- Full Text:
- Date Issued: 2014