Photocatalytic behaviour of tantalum (V) phthalocyanines in the presence of gold nanoparticles towards the oxidation of cyclohexene
- Chauke, Vongani P, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
Photocatalytic transformation of chlorophenols under homogeneous and heterogeneous conditions using palladium octadodecylthio phthalocyanine
- Ogunbayo, Taofeek B, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246816 , vital:51516 , xlink:href="https://doi.org/10.1016/j.molcata.2011.09.003"
- Description: Homogeneous and heterogeneous photosensitized transformations of 4-chlorophenol (4-CP) and pentachlorophenol (PCP) using palladium octadodecylthiophthalocyanine (PdODPc) were investigated. Under heterogeneous conditions, the photosensitizer was supported on functionalized single walled carbon nanotubes (SWCNTs). Homogeneous photosensitization proved to be more effective than the heterogeneous reaction in terms of percentage of transformation achieved. The kinetics of heterogeneous catalysis proved that ads-PdODPc–SWCNT–COOH (where SWCNT has been functionalized with COOH groups) was reusable for 4-CP while its activity degenerated when reused for PCP. Singlet oxygen was confirmed as playing an active role in the reactions.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246816 , vital:51516 , xlink:href="https://doi.org/10.1016/j.molcata.2011.09.003"
- Description: Homogeneous and heterogeneous photosensitized transformations of 4-chlorophenol (4-CP) and pentachlorophenol (PCP) using palladium octadodecylthiophthalocyanine (PdODPc) were investigated. Under heterogeneous conditions, the photosensitizer was supported on functionalized single walled carbon nanotubes (SWCNTs). Homogeneous photosensitization proved to be more effective than the heterogeneous reaction in terms of percentage of transformation achieved. The kinetics of heterogeneous catalysis proved that ads-PdODPc–SWCNT–COOH (where SWCNT has been functionalized with COOH groups) was reusable for 4-CP while its activity degenerated when reused for PCP. Singlet oxygen was confirmed as playing an active role in the reactions.
- Full Text:
- Date Issued: 2011
Photophysical and photochemical behavior of electrospun fibers of a polyurethane polymer chemically linked to lutetium carboxyphenoxy phthalocyanine
- Zugle, Ruhpino, Litwinski, Christian, Torto, Nelson, Nyokong, Tebello
- Authors: Zugle, Ruhpino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruhpino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
Photophysical behavior of zinc monoaminophthalocyanines linked to mercaptopropionic acid-capped CdTe quantum dots
- D'Souza, Sarah, Antunes, Edith M, Litwinski, Christian, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
Photophysical behaviour of asymmetrically substituted metal free, Mg and Zn phthalocyanines in the presence of folic acid
- Nombona, Nolwazi, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247705 , vital:51608 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.033"
- Description: This work reports on the synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines containing a mono carboxylic acid group for possible linking to biological molecules via an amide bond. Successful synthesis of the phthalocyanines was achieved through the statistical condensation method. The phthalocyanines were mixed with folic acid and their photophysical properties were examined. The triplet quantum yield values for all the complexes in DMSO were between 0.49 and 0.74 and in the presence of folic acid they were between 0.37 and 0.63. The lifetimes were generally good ranging from 70 to 290 μs in the absence or presence of folic acid.
- Full Text:
- Date Issued: 2011
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247705 , vital:51608 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.033"
- Description: This work reports on the synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines containing a mono carboxylic acid group for possible linking to biological molecules via an amide bond. Successful synthesis of the phthalocyanines was achieved through the statistical condensation method. The phthalocyanines were mixed with folic acid and their photophysical properties were examined. The triplet quantum yield values for all the complexes in DMSO were between 0.49 and 0.74 and in the presence of folic acid they were between 0.37 and 0.63. The lifetimes were generally good ranging from 70 to 290 μs in the absence or presence of folic acid.
- Full Text:
- Date Issued: 2011
Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions
- Zugle, Ruphino, Litwinski, Christian, Nyokong, Tebello
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
Phototransformation of 4-nitrophenol using Pd phthalocyanines supported on single walled carbon nanotubes
- Ogunbayo, Taofeek B, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247800 , vital:51619 , xlink:href="https://doi.org/10.1016/j.molcata.2011.01.016"
- Description: Adsorption of palladium phthalocyanines complexes on single walled carbon nanotubes was carried out. The resulting composites were employed as catalysts for heterogeneous photocatalytic oxidation of 4-nitrophenol (4-NP) in aqueous media. Singlet oxygen was found to be involved in the phototransformation of 4-NP. Gas chromatographic separation gave hydroquinone and benzoquinone as the phototransformation products. Langmuir–Hinshelwood (L–H) model was employed to evaluate the adsorption and desorption equilibria of the reactants and the products. 2,3,9,10,16,17,23,24-octakis(dodecylthiophthalocyaninato) palladium(II) and 1,4,8,11,15,18,22,25-octakis(dodecylthio phthalocyaninato) palladium, containing the longest alkyl chain gave the best performances.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247800 , vital:51619 , xlink:href="https://doi.org/10.1016/j.molcata.2011.01.016"
- Description: Adsorption of palladium phthalocyanines complexes on single walled carbon nanotubes was carried out. The resulting composites were employed as catalysts for heterogeneous photocatalytic oxidation of 4-nitrophenol (4-NP) in aqueous media. Singlet oxygen was found to be involved in the phototransformation of 4-NP. Gas chromatographic separation gave hydroquinone and benzoquinone as the phototransformation products. Langmuir–Hinshelwood (L–H) model was employed to evaluate the adsorption and desorption equilibria of the reactants and the products. 2,3,9,10,16,17,23,24-octakis(dodecylthiophthalocyaninato) palladium(II) and 1,4,8,11,15,18,22,25-octakis(dodecylthio phthalocyaninato) palladium, containing the longest alkyl chain gave the best performances.
- Full Text:
- Date Issued: 2011
Physical, political and local practice factors as barriers to agricultural development: a case of the Kat River valley, South Africa
- Mbatha, Cyril N, Antrobus, Geoffrey G
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142947 , vital:38178 , DOI: 10.2174/1874923201104010091
- Description: The Kat River Valley, in the Eastern Cape of South Africa, provided a case study against which propositions of determinants of economic development were tested. Physical location was found to matter in determining the level of development and economic leverage which Middle Kat farmers had compared to those downstream in accordance with Bromley's (1982) proposition. Physical location, however, was not a determining factor for farmers in the Upper Kat River who were the least developed. As predicted by Ostrom (1990), high transaction costs stemming from information asymmetries, selfish interests coupled with poor leadership, an unequal distribution of power and the flouting of formal agreements ensured the demise of a once successful Hacop project in the Upper Kat. Finally, Hirschman's (1960) much earlier line of argument was supported in that the nature of proposed development programmes and the compatibility with community values or ‘self images’ contributed to the lack of success of an externally initiated development effort. The findings and conclusion serve an important lesson to economic researchers and decision makers not to duplicate policies for implementation in all geographical and social contexts on the basis of their success elsewhere.
- Full Text:
- Date Issued: 2011
- Authors: Mbatha, Cyril N , Antrobus, Geoffrey G
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142947 , vital:38178 , DOI: 10.2174/1874923201104010091
- Description: The Kat River Valley, in the Eastern Cape of South Africa, provided a case study against which propositions of determinants of economic development were tested. Physical location was found to matter in determining the level of development and economic leverage which Middle Kat farmers had compared to those downstream in accordance with Bromley's (1982) proposition. Physical location, however, was not a determining factor for farmers in the Upper Kat River who were the least developed. As predicted by Ostrom (1990), high transaction costs stemming from information asymmetries, selfish interests coupled with poor leadership, an unequal distribution of power and the flouting of formal agreements ensured the demise of a once successful Hacop project in the Upper Kat. Finally, Hirschman's (1960) much earlier line of argument was supported in that the nature of proposed development programmes and the compatibility with community values or ‘self images’ contributed to the lack of success of an externally initiated development effort. The findings and conclusion serve an important lesson to economic researchers and decision makers not to duplicate policies for implementation in all geographical and social contexts on the basis of their success elsewhere.
- Full Text:
- Date Issued: 2011
Polygamy in the recognition of Customary Marriages Act:
- Authors: Vincent, Louise
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141809 , vital:38006 , DOI: 10.1080/10130950.2009.9676275
- Description: The Recognition of Customary Marriages Act (RCMA) 1998, recognises customary marriages which are “negotiated, celebrated or concluded according to any of the systems of indigenous African customary law which exist in South Africa” including polygamous marriages. The Act arises in the context of South Africa's Constitution which bans discrimination on grounds of culture and sexual orientation and allows for heterogeneity in its definitions of marriage and the family. A pluralist approach to family jurisprudence, however, is sometimes conceived of as setting up an irresolvable tension between the constitutional commitment to gender equality and protection for patriarchal prerogatives sanctioned by customary law. The fact that rights sometimes collide with one another is one of the reasons why it is impossible always to treat rights as absolute. When rights clash the question that arises is which of the rights that find themselves in tension with one another should give way and why?
- Full Text:
- Date Issued: 2011
- Authors: Vincent, Louise
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141809 , vital:38006 , DOI: 10.1080/10130950.2009.9676275
- Description: The Recognition of Customary Marriages Act (RCMA) 1998, recognises customary marriages which are “negotiated, celebrated or concluded according to any of the systems of indigenous African customary law which exist in South Africa” including polygamous marriages. The Act arises in the context of South Africa's Constitution which bans discrimination on grounds of culture and sexual orientation and allows for heterogeneity in its definitions of marriage and the family. A pluralist approach to family jurisprudence, however, is sometimes conceived of as setting up an irresolvable tension between the constitutional commitment to gender equality and protection for patriarchal prerogatives sanctioned by customary law. The fact that rights sometimes collide with one another is one of the reasons why it is impossible always to treat rights as absolute. When rights clash the question that arises is which of the rights that find themselves in tension with one another should give way and why?
- Full Text:
- Date Issued: 2011
Porphyrin nanorods modified glassy carbon electrode for the electrocatalysis of dioxygen, methanol and hydrazine
- George, Reama C, Mugadza, Tawanda, Khene, Samson, Egharevba, Gabriel O, Nyokong, Tebello
- Authors: George, Reama C , Mugadza, Tawanda , Khene, Samson , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247388 , vital:51576 , xlink:href="https://doi.org/10.1002/elan.201100081"
- Description: Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin molecules consisting of free base meso-tetraphenylsulfonate porphyrin (H4TPPS42−) and meso-tetra(N-methyl-4-pyridyl) porphyrin (MTMePyP4+M=Sn, Mn, In, Co). These consist of H4TPPS42−SnTMePyP4+, H4TPPS42−CoTMePyP4+, H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods. The absorption spectra and transmission electron microscopic (TEM) images of these structures were obtained. These porphyrin nanostructures were used to modify a glassy carbon electrode for the electrocatalytic reduction of oxygen, and the oxidation of hydrazine and methanol at low pH. The cyclic voltammogram of PNR-modified GCE in pH 2 buffer solution has five irreversible processes, two distinct reduction processes and three oxidation processes. The porphyrin nanorods modified GCE produce good responses especially towards oxygen reduction at −0.50 V vs. Ag|AgCl (3 M KCl). The process of electrocatalytic oxidation of methanol using PNR-modified GCE begins at 0.71 V vs. Ag|AgCl (3 M KCl). The electrochemical oxidation of hydrazine began at around 0.36 V on H4TPPS42−SnTMePyP4+ modified GCE. The GCE modified with H4TPPS42−CoTMePyP4+ H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods began oxidizing hydrazine at 0.54 V, 0.59 V and 0.56 V, respectively.
- Full Text:
- Date Issued: 2011
- Authors: George, Reama C , Mugadza, Tawanda , Khene, Samson , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247388 , vital:51576 , xlink:href="https://doi.org/10.1002/elan.201100081"
- Description: Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin molecules consisting of free base meso-tetraphenylsulfonate porphyrin (H4TPPS42−) and meso-tetra(N-methyl-4-pyridyl) porphyrin (MTMePyP4+M=Sn, Mn, In, Co). These consist of H4TPPS42−SnTMePyP4+, H4TPPS42−CoTMePyP4+, H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods. The absorption spectra and transmission electron microscopic (TEM) images of these structures were obtained. These porphyrin nanostructures were used to modify a glassy carbon electrode for the electrocatalytic reduction of oxygen, and the oxidation of hydrazine and methanol at low pH. The cyclic voltammogram of PNR-modified GCE in pH 2 buffer solution has five irreversible processes, two distinct reduction processes and three oxidation processes. The porphyrin nanorods modified GCE produce good responses especially towards oxygen reduction at −0.50 V vs. Ag|AgCl (3 M KCl). The process of electrocatalytic oxidation of methanol using PNR-modified GCE begins at 0.71 V vs. Ag|AgCl (3 M KCl). The electrochemical oxidation of hydrazine began at around 0.36 V on H4TPPS42−SnTMePyP4+ modified GCE. The GCE modified with H4TPPS42−CoTMePyP4+ H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods began oxidizing hydrazine at 0.54 V, 0.59 V and 0.56 V, respectively.
- Full Text:
- Date Issued: 2011
Privatisation, human rights and security: reflections on the draft international convention on regulation, oversight and monitoring of private military and security companies
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128800 , vital:36160 , http://dx.doi.org/10.4314/ldd.v15i1.3
- Description: Efforts to establish regulatory frameworks for private military/security companies (PMSCs), driven by public security concerns as well as private interests of the companies themselves, have yielded a number of soft law instruments. Unfortunately, most of these instruments are conditioned by the underlying interests of their promulgators and have therefore failed to establish universally acceptable regulatory standards.
- Full Text:
- Date Issued: 2011
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128800 , vital:36160 , http://dx.doi.org/10.4314/ldd.v15i1.3
- Description: Efforts to establish regulatory frameworks for private military/security companies (PMSCs), driven by public security concerns as well as private interests of the companies themselves, have yielded a number of soft law instruments. Unfortunately, most of these instruments are conditioned by the underlying interests of their promulgators and have therefore failed to establish universally acceptable regulatory standards.
- Full Text:
- Date Issued: 2011
Prof Nyokong receives another Science award
- Authors: Matiwana, Zamuxolo
- Date: 2011
- Subjects: Nyokong, Tebello , International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM)
- Language: English
- Type: Article , text
- Identifier: vital:7182 , http://hdl.handle.net/10962/d1006267 , Nyokong, Tebello
- Description: The Rhodes University professor of Medicinal Chemistry and Nanotechnology, Tebello Nyokong, says the Award for her Scientific Achievements by the International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM) is an honour, especially since it is awarded in memory of the centenary of the first Nobel Prize in Chemistry awarded to a woman: Marie Curie.
- Full Text:
- Date Issued: 2011
- Authors: Matiwana, Zamuxolo
- Date: 2011
- Subjects: Nyokong, Tebello , International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM)
- Language: English
- Type: Article , text
- Identifier: vital:7182 , http://hdl.handle.net/10962/d1006267 , Nyokong, Tebello
- Description: The Rhodes University professor of Medicinal Chemistry and Nanotechnology, Tebello Nyokong, says the Award for her Scientific Achievements by the International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM) is an honour, especially since it is awarded in memory of the centenary of the first Nobel Prize in Chemistry awarded to a woman: Marie Curie.
- Full Text:
- Date Issued: 2011
Putting old wine in new skins: the customary code of Lerotholi and justice administration in Lesotho
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/128780 , vital:36156 , https://doi.org/10.1017/CBO9780511844294.007
- Description: Although the interaction between the western colonizers and the African indigenous populations in the early eighteenth and nineteenth centuries produced responses that were mostly inimical to the development of African customary law, the thrust of the onslaught against its principles was somewhat diminished by political considerations. Undoubtedly, the significance that African customary law acquired during this period was a measure of the purpose that the colonial project found in it.
- Full Text: false
- Date Issued: 2011
Putting old wine in new skins: the customary code of Lerotholi and justice administration in Lesotho
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/128780 , vital:36156 , https://doi.org/10.1017/CBO9780511844294.007
- Description: Although the interaction between the western colonizers and the African indigenous populations in the early eighteenth and nineteenth centuries produced responses that were mostly inimical to the development of African customary law, the thrust of the onslaught against its principles was somewhat diminished by political considerations. Undoubtedly, the significance that African customary law acquired during this period was a measure of the purpose that the colonial project found in it.
- Full Text: false
- Date Issued: 2011
Records : history and genealogy of AmaCirha clan according to the Great House of the clan, beginning from the amaXhosa nation
- Date: 2011
- Subjects: Qangqolo, African chief Cirha (African people) -- South Africa -- History Ngcwanguba -- Eastern Cape -- South Africa -- History
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/41218 , vital:25066 , This manuscript is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PR 10 381
- Description: History and genealogy of AmaCirha clan according to the Great House of the clan, beginning from the amaXhosa nation. Sent to Prof Jeff Peires, Acting Head of Cory Library by M. L. Dyibhishe in 2011. , Dyibhishe, M L (donor)
- Full Text:
- Date Issued: 2011
- Date: 2011
- Subjects: Qangqolo, African chief Cirha (African people) -- South Africa -- History Ngcwanguba -- Eastern Cape -- South Africa -- History
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/41218 , vital:25066 , This manuscript is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PR 10 381
- Description: History and genealogy of AmaCirha clan according to the Great House of the clan, beginning from the amaXhosa nation. Sent to Prof Jeff Peires, Acting Head of Cory Library by M. L. Dyibhishe in 2011. , Dyibhishe, M L (donor)
- Full Text:
- Date Issued: 2011
Redox activity of CdTe quantum dots linked to nickel tetraaminophthalocyanine
- Khene, Samson, Nyokong, Tebello
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246457 , vital:51478 , xlink:href="https://doi.org/10.1016/j.microc.2011.06.024"
- Description: Cadmium tellurite quantum dots (CdTe-QDs) are linked to nickel tetraamino phthalocyanine (CdTe-QDs-NiTAPc) through an amide bond. Differential pulse voltammetry shows that that NiTAPc stabilizes the QDs against oxidative disintegration into metallic products on oxidation. Electrocatalytic oxidation of 2, 4-dichlorophenol (DCP) and pentachlorophenol (PCP) on CdTe-QDs and CdTe-QDs-NiTAPc adsorbed or electrodeposited onto a gold electrode were studied. Adsorbed CdTe-QDs-NiTAPc shows the lowest potential for DCP and PCP oxidation and it is also more stable to fouling by PCP and its oxidation products compared to adsorbed CdTe-QDs without NiTAPc. Electrodeposited CdTe-QDs or CdTe-QDs-NiTAPc show the best activity in terms of enhanced currents towards the oxidation of the chlorophenols.
- Full Text:
- Date Issued: 2011
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246457 , vital:51478 , xlink:href="https://doi.org/10.1016/j.microc.2011.06.024"
- Description: Cadmium tellurite quantum dots (CdTe-QDs) are linked to nickel tetraamino phthalocyanine (CdTe-QDs-NiTAPc) through an amide bond. Differential pulse voltammetry shows that that NiTAPc stabilizes the QDs against oxidative disintegration into metallic products on oxidation. Electrocatalytic oxidation of 2, 4-dichlorophenol (DCP) and pentachlorophenol (PCP) on CdTe-QDs and CdTe-QDs-NiTAPc adsorbed or electrodeposited onto a gold electrode were studied. Adsorbed CdTe-QDs-NiTAPc shows the lowest potential for DCP and PCP oxidation and it is also more stable to fouling by PCP and its oxidation products compared to adsorbed CdTe-QDs without NiTAPc. Electrodeposited CdTe-QDs or CdTe-QDs-NiTAPc show the best activity in terms of enhanced currents towards the oxidation of the chlorophenols.
- Full Text:
- Date Issued: 2011
Remains to be said: The "um" in art and other disfluencies
- Authors: de Jager, Maureen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147369 , vital:38630 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC45815
- Description: Taking as my starting point an artwork of "fillers" - a 2010 sound piece by Fine Art student Romie Sciscio foregrounding the disfluent speech of various visiting academics to the Department of Fine Art, Rhodes University - I propose that speech disfluencies such as "um", "kind of" and "I suppose" should not simply be derided as white noise or verbal graffiti. Rather, filled pauses - understood both literally and metaphorically - may be seen to function critically, precisely because they are located neither inside nor outside the "message" of speech. They hover between presence and absence, seemingly content-less and yet dimly portentous: they do and do not matter to meaning. As such, they require (or provoke and demand) a different kind of listening - the acoustic equivalent of reading between the lines.
- Full Text:
- Date Issued: 2011
- Authors: de Jager, Maureen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147369 , vital:38630 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC45815
- Description: Taking as my starting point an artwork of "fillers" - a 2010 sound piece by Fine Art student Romie Sciscio foregrounding the disfluent speech of various visiting academics to the Department of Fine Art, Rhodes University - I propose that speech disfluencies such as "um", "kind of" and "I suppose" should not simply be derided as white noise or verbal graffiti. Rather, filled pauses - understood both literally and metaphorically - may be seen to function critically, precisely because they are located neither inside nor outside the "message" of speech. They hover between presence and absence, seemingly content-less and yet dimly portentous: they do and do not matter to meaning. As such, they require (or provoke and demand) a different kind of listening - the acoustic equivalent of reading between the lines.
- Full Text:
- Date Issued: 2011
Report on the Mesozoic volcanic and intrusive rocks on the Namibe Basin, Southwest Angola:
- Authors: Marsh, Julian S
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144846 , vital:38384
- Description: The Bero Volcanic Complex comprises a diverse group of quartz latite and tholeiitic basalt lavas, pyroclastic and volcaniclastic deposits, aeolian sandstones as well as intrusive tholeiitic mafic dykes and gabbros. Only the silicic members of this suite have received prior attention being referred to as “granitic porphyries” by Carvalho (1961) who regarded them as being Precambrian in age. Alberti et al.(1992) informally referred to these silicic rocks as the ‘Giraul Volcanics’ and correlated them with the early Cretaceous Paraná-Etendeka Igneous Province of Brazil and Namibia.
- Full Text:
- Date Issued: 2011
- Authors: Marsh, Julian S
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144846 , vital:38384
- Description: The Bero Volcanic Complex comprises a diverse group of quartz latite and tholeiitic basalt lavas, pyroclastic and volcaniclastic deposits, aeolian sandstones as well as intrusive tholeiitic mafic dykes and gabbros. Only the silicic members of this suite have received prior attention being referred to as “granitic porphyries” by Carvalho (1961) who regarded them as being Precambrian in age. Alberti et al.(1992) informally referred to these silicic rocks as the ‘Giraul Volcanics’ and correlated them with the early Cretaceous Paraná-Etendeka Igneous Province of Brazil and Namibia.
- Full Text:
- Date Issued: 2011
Rethinking ‘actually-existing’ public spheres:
- Authors: Garman, Anthea
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159869 , vital:40351 , DOI: 10.1080/02560054.2011.621292
- Description: The idea of the usefulness and efficacy of the public sphere, and the notion of publicness it employs, is one which continues to resonate in modern-day liberal democracies as a mechanism to engage citizens in national matters. It also serves as a check on unfettered power and particularly as a rationale for the news media and their operations.
- Full Text:
- Date Issued: 2011
- Authors: Garman, Anthea
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159869 , vital:40351 , DOI: 10.1080/02560054.2011.621292
- Description: The idea of the usefulness and efficacy of the public sphere, and the notion of publicness it employs, is one which continues to resonate in modern-day liberal democracies as a mechanism to engage citizens in national matters. It also serves as a check on unfettered power and particularly as a rationale for the news media and their operations.
- Full Text:
- Date Issued: 2011
Rhodes University 2011 Graduation Ceremonies Address
- Authors: Badat, Saleem
- Date: 2011
- Language: English
- Type: text
- Identifier: vital:7587 , http://hdl.handle.net/10962/d1006578
- Description: From introduction: To be awarded a degree, diploma or certificate from Rhodes University entails dedicated endeavour. When you joined us you were told that at Rhodes learning and education is a partnership of mutual commitment to the pursuit of knowledge and understanding, to the development of expertise and skills, and to the embrace of appropriate values and attitudes. Your graduation this evening/afternoon/morning is testimony that you have fulfilled your side of the partnership. You have displayed the necessary commitment to learn, to acquire knowledge and to develop expertise.
- Full Text:
- Date Issued: 2011
- Authors: Badat, Saleem
- Date: 2011
- Language: English
- Type: text
- Identifier: vital:7587 , http://hdl.handle.net/10962/d1006578
- Description: From introduction: To be awarded a degree, diploma or certificate from Rhodes University entails dedicated endeavour. When you joined us you were told that at Rhodes learning and education is a partnership of mutual commitment to the pursuit of knowledge and understanding, to the development of expertise and skills, and to the embrace of appropriate values and attitudes. Your graduation this evening/afternoon/morning is testimony that you have fulfilled your side of the partnership. You have displayed the necessary commitment to learn, to acquire knowledge and to develop expertise.
- Full Text:
- Date Issued: 2011
Rhodes University Graduation Ceremony 2011
- Authors: Rhodes University
- Date: 2011
- Language: English
- Type: text
- Identifier: vital:8136 , http://hdl.handle.net/10962/d1007246
- Description: Rhodes University Graduation Ceremonies [at] 1820 Settlers National Monument Thursday, 7 April at 18.00 [and] Friday, 8 April at 10:30; 14:30 & 18:00 [and] Saturday, 9 April at 10:30
- Full Text:
- Date Issued: 2011
- Authors: Rhodes University
- Date: 2011
- Language: English
- Type: text
- Identifier: vital:8136 , http://hdl.handle.net/10962/d1007246
- Description: Rhodes University Graduation Ceremonies [at] 1820 Settlers National Monument Thursday, 7 April at 18.00 [and] Friday, 8 April at 10:30; 14:30 & 18:00 [and] Saturday, 9 April at 10:30
- Full Text:
- Date Issued: 2011