Comparative efficiency of immobilized non-transition metal phthalocyanine photosensitizers for the visible light transformation of chlorophenols
- Agboola, Bolade, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
Synthesis and photophysical properties of octa-substituted phthalocyaninato oxotitanium (IV) derivatives
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283881 , vital:55999 , xlink:href="https://doi.org/10.1142/S1088424606000399"
- Description: The synthesis, spectral and photophysical properties including fluorescence quenching of the following octa-substituted oxotitanium phthalocyanines are reported: 2,3,9,10,16,17,23,24-octaphenoxyphthalocyaninato titanium(IV) oxide, 2,3,9,10,16,17,23,24-[octakis(4-t-butylphenoxyphthalocyaninato)]titanium(IV) oxide, 2,3,9,10,16,17,23,24-{octakis[(4-benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide and 2,3,9,10,16,17,23,24-octaphenylthiophthalocyaninato titanium(IV) oxide. The complexes are characterized by 1H NMR, IR and UV-vis spectroscopies. Their photophysical properties are presented where moderate fluorescence quantum yields (0.14-0.19) and lifetimes were determined. Varied triplet quantum yields were obtained and the triplet lifetimes (40-100 μs) were short.
- Full Text:
- Date Issued: 2006
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283881 , vital:55999 , xlink:href="https://doi.org/10.1142/S1088424606000399"
- Description: The synthesis, spectral and photophysical properties including fluorescence quenching of the following octa-substituted oxotitanium phthalocyanines are reported: 2,3,9,10,16,17,23,24-octaphenoxyphthalocyaninato titanium(IV) oxide, 2,3,9,10,16,17,23,24-[octakis(4-t-butylphenoxyphthalocyaninato)]titanium(IV) oxide, 2,3,9,10,16,17,23,24-{octakis[(4-benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide and 2,3,9,10,16,17,23,24-octaphenylthiophthalocyaninato titanium(IV) oxide. The complexes are characterized by 1H NMR, IR and UV-vis spectroscopies. Their photophysical properties are presented where moderate fluorescence quantum yields (0.14-0.19) and lifetimes were determined. Varied triplet quantum yields were obtained and the triplet lifetimes (40-100 μs) were short.
- Full Text:
- Date Issued: 2006
Joking around in Zimbabwe, undoing and redoing participation
- Authors: Price, Leigh
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373715 , vital:66716 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122750"
- Description: In Zimbabwe, I teach a participatory course on environmental education to trainers. The course is an adaptation of a course designed by Rhodes University, South Africa. It gives participants a background in educational theories and has a strong theoretical component built around a focus on practice. During the time that the course was being delivered to non-industry participants, the theoretical component of the course was whole-heartedly embraced. We assumed that calling the course ‘participatory’ presupposed the need for this theory because within the theory were the tools for emancipation. And participation, we believed, had an emancipatory mandate. However, when we decided to redevelop the course for industry, we were uncomfortably surprised by the request from a majority of industry participants to reduce the theory and concentrate solely on skills-based training. This paper documents how this discomfort resulted in my adjusting my view of participation.
- Full Text:
- Date Issued: 2006
- Authors: Price, Leigh
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373715 , vital:66716 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122750"
- Description: In Zimbabwe, I teach a participatory course on environmental education to trainers. The course is an adaptation of a course designed by Rhodes University, South Africa. It gives participants a background in educational theories and has a strong theoretical component built around a focus on practice. During the time that the course was being delivered to non-industry participants, the theoretical component of the course was whole-heartedly embraced. We assumed that calling the course ‘participatory’ presupposed the need for this theory because within the theory were the tools for emancipation. And participation, we believed, had an emancipatory mandate. However, when we decided to redevelop the course for industry, we were uncomfortably surprised by the request from a majority of industry participants to reduce the theory and concentrate solely on skills-based training. This paper documents how this discomfort resulted in my adjusting my view of participation.
- Full Text:
- Date Issued: 2006
Unique electrochemical behavior of tantalum (V) phthalocyanine
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286139 , vital:56243 , xlink:href="https://doi.org/10.1142/S1088424606000090"
- Description: The electrochemical and spectroscopic behavior of tantalum(V) phthalocyanine are presented. The NMR spectra is consistent with the lack of symmetry of the complex. Cyclic (CV) and square wave (SWV) voltammetries, and spectroelectrochemistry, were employed in the study of the complex. Two one-electron reductions and a simultaneous 4-electron reduction were observed. Reduction occurs first at the metal to form a Ta(IV) species, followed by ring based processes.
- Full Text:
- Date Issued: 2006
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286139 , vital:56243 , xlink:href="https://doi.org/10.1142/S1088424606000090"
- Description: The electrochemical and spectroscopic behavior of tantalum(V) phthalocyanine are presented. The NMR spectra is consistent with the lack of symmetry of the complex. Cyclic (CV) and square wave (SWV) voltammetries, and spectroelectrochemistry, were employed in the study of the complex. Two one-electron reductions and a simultaneous 4-electron reduction were observed. Reduction occurs first at the metal to form a Ta(IV) species, followed by ring based processes.
- Full Text:
- Date Issued: 2006
Electropolymerizable iron (III) and cobalt (II) dicyanophenoxy tetraphenylporphyrin complexes
- Ozoemena, Kenneth I, Zhao, Zhixin, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
The Condictio Indebiti and Unjust Factors (1)
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186869 , vital:44541 , xlink:href="file:///C:/Users/User/Downloads/69THRHR419%20(2).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186869 , vital:44541 , xlink:href="file:///C:/Users/User/Downloads/69THRHR419%20(2).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
Comparative electrochemistry and electrocatalytic activities of cobalt, iron and manganese phthalocyanine complexes axially co-ordinated to mercaptopyridine self-assembled monolayer at gold electrodes
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286054 , vital:56234 , xlink:href="https://doi.org/10.1016/j.electacta.2005.08.007"
- Description: Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards L-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286054 , vital:56234 , xlink:href="https://doi.org/10.1016/j.electacta.2005.08.007"
- Description: Comparative surface electrochemistry and electrocatalytic properties of solid ultrathin monolayer films of metallophthalocyanine (MPc) complexes of cobalt (CoPc), iron (FePc) and manganese (MnPc) self-immobilised, via axial ligation reaction, onto preformed 4-mercaptopyridine self-assembled monolayers (SAMs) on gold electrodes have been described. Surface electrochemical parameters of the modified electrodes showed that these MPc-SAMs are densely packed with flat orientations. The electrochemical, electrocatalytic and stability properties of these MPc complexes follow this order: FePc > MnPc > CoPc. This finding is remarkable as it suggests that the success of using this method of self-assembling of MPc onto gold electrode is largely dependent on the bond distance between the pyridine linker and the central metal of the MPc; the shorter the distance, the faster the co-ordination and the better the electrocatalytic properties towards L-cysteine and thiocyanate. Thus, the superiority of FePc-based SAM over those of the MnPc and CoPc, has been proposed to be the result of the more favorable axial co-ordination properties of FePc with pyridine (i.e. shorter Fe–N(pyridine) bond length.
- Full Text:
- Date Issued: 2006
The effect of Ge, Si and Sn phthalocyanine photosensitizers on cell proliferation and viability of human oesophageal carcinoma cells
- Seotsanyana-Mokhosi, Itumeleng, Kresfelder, Tina, Abrahamse, Heidi, Nyokong, Tebello
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kresfelder, Tina , Abrahamse, Heidi , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286115 , vital:56241 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2005.12.004"
- Description: The photodynamic activity of water soluble mixed sulfonated metallophthalocyanines complexes: GePcSmix, SnPcSmix and SiPcSmix on human oesophageal carcinoma (SNO) cells are reported, and compared with the activity of the unmetallated H2PcSmix and of the newly synthesized water soluble adjacently substituted binaphthalo phthalocyanine (complex 3). The alkaline phosphate (ALP) showed damage to the cell membrane in the presence of complex 3 without irradiation. The GePcSmix complex caused a relatively large increase in inflammation and a high intracellular ATP.
- Full Text:
- Date Issued: 2006
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kresfelder, Tina , Abrahamse, Heidi , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286115 , vital:56241 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2005.12.004"
- Description: The photodynamic activity of water soluble mixed sulfonated metallophthalocyanines complexes: GePcSmix, SnPcSmix and SiPcSmix on human oesophageal carcinoma (SNO) cells are reported, and compared with the activity of the unmetallated H2PcSmix and of the newly synthesized water soluble adjacently substituted binaphthalo phthalocyanine (complex 3). The alkaline phosphate (ALP) showed damage to the cell membrane in the presence of complex 3 without irradiation. The GePcSmix complex caused a relatively large increase in inflammation and a high intracellular ATP.
- Full Text:
- Date Issued: 2006
Self-assembled monolayers (SAMs) of cobalt tetracarboxylic acidchloride phthalocyanine covalently attached onto a preformed mercaptoethanol SAM
- Mashazi, Philani N, Ozoemena, Kenneth I, Maree, David M, Nyokong, Tebello
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Maree, David M , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283792 , vital:55989 , xlink:href="https://doi.org/10.1016/j.electacta.2005.10.004"
- Description: A feasible method of fabricating phthalocyanine sensor was developed by covalent attachment of cobalt tetracarboxylic acidchloride phthalocyanine (CoTCACIPc) onto a preformed 2-mercaptoethanol (2-ME) self-assembled monolayer (SAM) modified gold electrode (designated as CoTCACIPc-2-ME-SAM). The surface concentration of the CoTCACIPc was found to be 4.58 × 10−10 mol/cm2. The sensor gave a linear response to L-cysteine over the concentration range 0.28–20 μM with a detection limit of 5 × 10−7 M and best response time of 2 s.
- Full Text:
- Date Issued: 2006
- Authors: Mashazi, Philani N , Ozoemena, Kenneth I , Maree, David M , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283792 , vital:55989 , xlink:href="https://doi.org/10.1016/j.electacta.2005.10.004"
- Description: A feasible method of fabricating phthalocyanine sensor was developed by covalent attachment of cobalt tetracarboxylic acidchloride phthalocyanine (CoTCACIPc) onto a preformed 2-mercaptoethanol (2-ME) self-assembled monolayer (SAM) modified gold electrode (designated as CoTCACIPc-2-ME-SAM). The surface concentration of the CoTCACIPc was found to be 4.58 × 10−10 mol/cm2. The sensor gave a linear response to L-cysteine over the concentration range 0.28–20 μM with a detection limit of 5 × 10−7 M and best response time of 2 s.
- Full Text:
- Date Issued: 2006
Synthesis and electrochemical characterisation of α-and β-tetra-substituted oxo (phthalocyaninato) titanium (IV) complexes
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
- Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
- Full Text:
- Date Issued: 2006
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
- Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
- Full Text:
- Date Issued: 2006
UV-Visible and Electrochemical Monitoring of Carbon Monoxide Release by Donor Complexes to Myoglobin Solutions and to Electrodes Modified with Films Containing Hemin
- Obirai, Joseph C, Hamadi, Sara, Ithurbide, Aurélie, Wartelle, Corinne, Nyokong, Tebello, Zagal, José, Top, Siden, Bedioui, Fethi
- Authors: Obirai, Joseph C , Hamadi, Sara , Ithurbide, Aurélie , Wartelle, Corinne , Nyokong, Tebello , Zagal, José , Top, Siden , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283906 , vital:56001 , xlink:href="https://doi.org/10.1002/elan.200603571"
- Description: This study reports on the evaluation of the CO donating behavior of tricarbonyl dichloro ruthenium(II) dimer ([Ru(CO)3Cl2]2) and 1,3-dimethoxyphenyl tricarbonyl chromium (C6H3(MeO)2Cr(CO)3) complex by UV-visible technique and electrochemical technique. The CO release was monitored by following the modifications of the UV-visible features of MbFe(II) in phosphate buffer solution and the redox features of reduced Hemin, HmFe(II), confined at the surface of a vitreous carbon electrode. In the latter case, the interaction between the hemin-modified electrode and the released CO was seen through the observation of an increase of the reduction current related to the FeIII/FeII redox process of the immobilized porphyrin. While the ruthenium-based complex, ([Ru(CO)3Cl2]2), depended on the presence of Fe(II) species to release CO, it was found that the chromium-based complex released spontaneously CO. This was facilitated by illuminating and/or simple stirring of the solution containing the complex.
- Full Text:
- Date Issued: 2006
- Authors: Obirai, Joseph C , Hamadi, Sara , Ithurbide, Aurélie , Wartelle, Corinne , Nyokong, Tebello , Zagal, José , Top, Siden , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283906 , vital:56001 , xlink:href="https://doi.org/10.1002/elan.200603571"
- Description: This study reports on the evaluation of the CO donating behavior of tricarbonyl dichloro ruthenium(II) dimer ([Ru(CO)3Cl2]2) and 1,3-dimethoxyphenyl tricarbonyl chromium (C6H3(MeO)2Cr(CO)3) complex by UV-visible technique and electrochemical technique. The CO release was monitored by following the modifications of the UV-visible features of MbFe(II) in phosphate buffer solution and the redox features of reduced Hemin, HmFe(II), confined at the surface of a vitreous carbon electrode. In the latter case, the interaction between the hemin-modified electrode and the released CO was seen through the observation of an increase of the reduction current related to the FeIII/FeII redox process of the immobilized porphyrin. While the ruthenium-based complex, ([Ru(CO)3Cl2]2), depended on the presence of Fe(II) species to release CO, it was found that the chromium-based complex released spontaneously CO. This was facilitated by illuminating and/or simple stirring of the solution containing the complex.
- Full Text:
- Date Issued: 2006
Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis
- Nyokong, Tebello, Bedioui, Fethi
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283826 , vital:55994 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283826 , vital:55994 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
The Condictio Indebiti and Unjust Factors (2)
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186880 , vital:44544 , xlink:href="///C:/Users/User/Downloads/69THRHR561%20(1).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186880 , vital:44544 , xlink:href="///C:/Users/User/Downloads/69THRHR561%20(1).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
Actor/actant-network theory as emerging methodology for environmental education research in southern Africa
- Authors: Nhamo, Godwell
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373553 , vital:66701 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122722"
- Description: This paper deliberates on actor/actant-network theory (AANT) as methodology for policy research in environmental education (EE). Insights are drawn from work that applied AANT to research environmental policy processes surrounding the formulation and implementation of South Africa’s Plastic Bags Regulations of 2003. The paper reveals that the application of AANT methodology made it possible to trace relationships, actors, actants and actor/actant-networks surrounding the Plastic Bags Regulations as quasi-object (token). The methodology also enabled a focus on understanding and investigating tensions, debates and responses emerging from the policy process. The findings were that after the promulgation of the first draft of the Plastic Bags Regulations in May 2000, tensions emerged around the nature of regulation (whether to use the command and control approach – preferred by Organised Government – or self regulation – preferred by Organised Business and Organised Labour). From these findings, a series of conceptual frameworks were drawn up as identified around key actors and actor/actant-networks. The conceptual frameworks included among them, Organised Government, Organised Business and Organised Labour.
- Full Text: false
- Date Issued: 2006
- Authors: Nhamo, Godwell
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373553 , vital:66701 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122722"
- Description: This paper deliberates on actor/actant-network theory (AANT) as methodology for policy research in environmental education (EE). Insights are drawn from work that applied AANT to research environmental policy processes surrounding the formulation and implementation of South Africa’s Plastic Bags Regulations of 2003. The paper reveals that the application of AANT methodology made it possible to trace relationships, actors, actants and actor/actant-networks surrounding the Plastic Bags Regulations as quasi-object (token). The methodology also enabled a focus on understanding and investigating tensions, debates and responses emerging from the policy process. The findings were that after the promulgation of the first draft of the Plastic Bags Regulations in May 2000, tensions emerged around the nature of regulation (whether to use the command and control approach – preferred by Organised Government – or self regulation – preferred by Organised Business and Organised Labour). From these findings, a series of conceptual frameworks were drawn up as identified around key actors and actor/actant-networks. The conceptual frameworks included among them, Organised Government, Organised Business and Organised Labour.
- Full Text: false
- Date Issued: 2006
Electrocatalytic oxidation of thiocyanate, L-cysteine and 2-mercaptoethanol by self-assembled monolayer of cobalt tetraethoxy thiophene phthalocyanine
- Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283814 , vital:55993 , xlink:href="https://doi.org/10.1016/j.electacta.2005.12.024"
- Description: Catalytic activity of a self-assembled monolayer (SAM) of cobalt tetra ethoxythiophene phthalocyanine (CoTEThPc-SAM) complex towards oxidation of thiocyanate (SCN−), L-cysteine (CYS) and 2-mercaptoethanol (2-ME) is reported. The oxidation of thiocyanate occurs via a two electron transfer, whereas L-cysteine and 2-ME require 1 electron. The oxidation of thiocyanate is catalysed by ring based processes, while L-cysteine is catalysed by both CoIII/CoII process and by ring based processes. 2-ME is catalysed by CoIII/CoII process. The oxidation of thiocyanate on CoTEThPc was performed in acid media instead of basic media commonly employed. The reaction order was found to be unity for all the analytes, showing that only one molecule of analyte interacts with one molecule of the catalyst during the rate determining step.
- Full Text:
- Date Issued: 2006
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283814 , vital:55993 , xlink:href="https://doi.org/10.1016/j.electacta.2005.12.024"
- Description: Catalytic activity of a self-assembled monolayer (SAM) of cobalt tetra ethoxythiophene phthalocyanine (CoTEThPc-SAM) complex towards oxidation of thiocyanate (SCN−), L-cysteine (CYS) and 2-mercaptoethanol (2-ME) is reported. The oxidation of thiocyanate occurs via a two electron transfer, whereas L-cysteine and 2-ME require 1 electron. The oxidation of thiocyanate is catalysed by ring based processes, while L-cysteine is catalysed by both CoIII/CoII process and by ring based processes. 2-ME is catalysed by CoIII/CoII process. The oxidation of thiocyanate on CoTEThPc was performed in acid media instead of basic media commonly employed. The reaction order was found to be unity for all the analytes, showing that only one molecule of analyte interacts with one molecule of the catalyst during the rate determining step.
- Full Text:
- Date Issued: 2006
Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis
- Nyokong, Tebello, Bedioui, Fethi
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283851 , vital:55996 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283851 , vital:55996 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
Actor/actant-network theory as emerging methodology for environmental education research in southern Africa
- Authors: Nhamo, Godwell
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373537 , vital:66702 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122722"
- Description: This paper deliberates on actor/actant-network theory (AANT) as methodology for policy research in environmental education (EE). Insights are drawn from work that applied AANT to research environmental policy processes surrounding the formulation and implementation of South Africa’s Plastic Bags Regulations of 2003. The paper reveals that the application of AANT methodology made it possible to trace relationships, actors, actants and actor/actant-networks surrounding the Plastic Bags Regulations as quasi-object (token). The methodology also enabled a focus on understanding and investigating tensions, debates and responses emerging from the policy process. The findings were that after the promulgation of the first draft of the Plastic Bags Regulations in May 2000, tensions emerged around the nature of regulation (whether to use the command and control approach – preferred by Organised Government – or self regulation – preferred by Organised Business and Organised Labour). From these findings, a series of conceptual frameworks were drawn up as identified around key actors and actor/actant-networks. The conceptual frameworks included among them, Organised Government, Organised Business and Organised Labour.
- Full Text:
- Date Issued: 2006
- Authors: Nhamo, Godwell
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373537 , vital:66702 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122722"
- Description: This paper deliberates on actor/actant-network theory (AANT) as methodology for policy research in environmental education (EE). Insights are drawn from work that applied AANT to research environmental policy processes surrounding the formulation and implementation of South Africa’s Plastic Bags Regulations of 2003. The paper reveals that the application of AANT methodology made it possible to trace relationships, actors, actants and actor/actant-networks surrounding the Plastic Bags Regulations as quasi-object (token). The methodology also enabled a focus on understanding and investigating tensions, debates and responses emerging from the policy process. The findings were that after the promulgation of the first draft of the Plastic Bags Regulations in May 2000, tensions emerged around the nature of regulation (whether to use the command and control approach – preferred by Organised Government – or self regulation – preferred by Organised Business and Organised Labour). From these findings, a series of conceptual frameworks were drawn up as identified around key actors and actor/actant-networks. The conceptual frameworks included among them, Organised Government, Organised Business and Organised Labour.
- Full Text:
- Date Issued: 2006
An Exploration of How Natural Resource Management (NRM) Discourse is Integrated into Key Pedagogic Texts
- Authors: Nsubuga, Yvonne
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373552 , vital:66703 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122753"
- Description: Natural resource management (NRM) education has the potential to improve the quality and relevance of rural education in South Africa. For this potential to be realised, the various educational resources that are commonly used by teachers and learners in rural schools need to incorporate natural resource management knowledge. Using Bernstein’s concepts of classification and his theories on recontextualisation, a content analysis study was carried out to compare the level of NRM integration within the Grade 10 Life Sciences syllabus, and a Grade 10 Life Sciences textbook. Results from the analysis of the syllabus showed that overall only 9% of all the knowledge statements analysed had a strong link to NRM and related issues. The highest percentage of such sentences was found in the Core Knowledge section of the syllabus (21%). For the textbook, only 8% of the analysed items had a strong link to NRM and related issues, with the highest percentage of such items occurring in the Suggested Activities section (16%). However, the level of NRM integration in both documents increased considerably when sentences that had only an implicit link to NRM and related issues were included. It was concluded that both documents provide ample opportunities for NRM learning, although the extent to which this occurs varies among their different sections. The recontextualising role of the Grade 10 Life Sciences textbook was reflected in its relatively higher level of NRM integration in the Suggested Activities category, and in the Glossary category. This study highlights the need for further strengthening of the position of NRM within the Grade 10 Life Sciences syllabus, and for more Bernstein-based research to inform South Africa’s curriculum reform initiatives in environmental education.
- Full Text:
- Date Issued: 2006
- Authors: Nsubuga, Yvonne
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373552 , vital:66703 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122753"
- Description: Natural resource management (NRM) education has the potential to improve the quality and relevance of rural education in South Africa. For this potential to be realised, the various educational resources that are commonly used by teachers and learners in rural schools need to incorporate natural resource management knowledge. Using Bernstein’s concepts of classification and his theories on recontextualisation, a content analysis study was carried out to compare the level of NRM integration within the Grade 10 Life Sciences syllabus, and a Grade 10 Life Sciences textbook. Results from the analysis of the syllabus showed that overall only 9% of all the knowledge statements analysed had a strong link to NRM and related issues. The highest percentage of such sentences was found in the Core Knowledge section of the syllabus (21%). For the textbook, only 8% of the analysed items had a strong link to NRM and related issues, with the highest percentage of such items occurring in the Suggested Activities section (16%). However, the level of NRM integration in both documents increased considerably when sentences that had only an implicit link to NRM and related issues were included. It was concluded that both documents provide ample opportunities for NRM learning, although the extent to which this occurs varies among their different sections. The recontextualising role of the Grade 10 Life Sciences textbook was reflected in its relatively higher level of NRM integration in the Suggested Activities category, and in the Glossary category. This study highlights the need for further strengthening of the position of NRM within the Grade 10 Life Sciences syllabus, and for more Bernstein-based research to inform South Africa’s curriculum reform initiatives in environmental education.
- Full Text:
- Date Issued: 2006
Teacher-community cooperation to promote sustainability of wetlands in Kenya
- Authors: Ndaruga, Ayub M , Irwin, Pat
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373860 , vital:66728 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122727"
- Description: This study was undertaken with 83 teachers from 54 primary schools in Kenya. Its purpose was to establish how teachers relate with the local community and how they harness this interaction to promote sustainability of wetlands within their locality. Data were collected using questionnaires, interviews and observation. Results of the study indicated that teachers acknowledge the value of, and threats to, their local wetlands. Some teachers reported interacting and engaging in diverse activities with members of the community to conserve the local wetlands. Forums for interaction and action mentioned by the teachers included public baraza, women’s groups, church, youth groups, local community, parents’ meetings and environmental days. Use of these forums differed. The approaches used to involve the community in awareness and action ranged from theoretical arguments to visits to wetlands, use of wetland resources, ecomanagement and political action. The responses by teachers revealed lack of engagement with the real local wetland problems. This study demonstrated existence of a potential but under-utilised opportunity that can be harnessed by environmental education programmes to champion the sustainability of wetlands.
- Full Text:
- Date Issued: 2006
- Authors: Ndaruga, Ayub M , Irwin, Pat
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/373860 , vital:66728 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122727"
- Description: This study was undertaken with 83 teachers from 54 primary schools in Kenya. Its purpose was to establish how teachers relate with the local community and how they harness this interaction to promote sustainability of wetlands within their locality. Data were collected using questionnaires, interviews and observation. Results of the study indicated that teachers acknowledge the value of, and threats to, their local wetlands. Some teachers reported interacting and engaging in diverse activities with members of the community to conserve the local wetlands. Forums for interaction and action mentioned by the teachers included public baraza, women’s groups, church, youth groups, local community, parents’ meetings and environmental days. Use of these forums differed. The approaches used to involve the community in awareness and action ranged from theoretical arguments to visits to wetlands, use of wetland resources, ecomanagement and political action. The responses by teachers revealed lack of engagement with the real local wetland problems. This study demonstrated existence of a potential but under-utilised opportunity that can be harnessed by environmental education programmes to champion the sustainability of wetlands.
- Full Text:
- Date Issued: 2006
Identifying needs and opportunities for local government environmental education and training in South Africa
- Olvitt, Lausanne L, Hamaamba, Tyson
- Authors: Olvitt, Lausanne L , Hamaamba, Tyson
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370991 , vital:66400 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122739"
- Description: Effective environmental management and public engagement with environmental concerns are needed for the attainment of sustainable development goals and socio-ecological balance in local government contexts. This vision is clearly articulated in international environmental policy frameworks and in South Africa’s national and regional legislation. However, policy and legislation fall short of identifying the range of a priori competences required by local government officials and environmental managers before well intended policy can be translated into effective practice. This paper reports on recent research into identifying the underlying competences required for better environmental management and the establishment of education and training processes for local government managers. The research draws on the notion of ‘applied competence’ put forward by South Africa’s National Qualifications Framework, and argues that greater attention needs to be paid to competence-based capacity building processes within local government departments if environmental sustainability and development goals are to be met. The paper draws on the researchers’ experiences of formulating a national level generic competence framework for environmental management, and conducting an education and training needs analysis for the Makana Municipality in the Eastern Cape province of South Africa. Early findings suggest that a broad range of competences all have a role in ensuring the capacity and effectiveness of local governments to better manage their local environment. The paper argues that these are significant for the development of environmental education and training programmes in local government contexts.
- Full Text:
- Date Issued: 2006
- Authors: Olvitt, Lausanne L , Hamaamba, Tyson
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370991 , vital:66400 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122739"
- Description: Effective environmental management and public engagement with environmental concerns are needed for the attainment of sustainable development goals and socio-ecological balance in local government contexts. This vision is clearly articulated in international environmental policy frameworks and in South Africa’s national and regional legislation. However, policy and legislation fall short of identifying the range of a priori competences required by local government officials and environmental managers before well intended policy can be translated into effective practice. This paper reports on recent research into identifying the underlying competences required for better environmental management and the establishment of education and training processes for local government managers. The research draws on the notion of ‘applied competence’ put forward by South Africa’s National Qualifications Framework, and argues that greater attention needs to be paid to competence-based capacity building processes within local government departments if environmental sustainability and development goals are to be met. The paper draws on the researchers’ experiences of formulating a national level generic competence framework for environmental management, and conducting an education and training needs analysis for the Makana Municipality in the Eastern Cape province of South Africa. Early findings suggest that a broad range of competences all have a role in ensuring the capacity and effectiveness of local governments to better manage their local environment. The paper argues that these are significant for the development of environmental education and training programmes in local government contexts.
- Full Text:
- Date Issued: 2006