A description of gametogenesis in the panga Pterogymnus laniarius (Pisces: Sparidae) with comments on changes in maturity patterns over the past two decades
- Booth, Anthony J, Hecht, Thomas
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446930 , vital:74571 , https://www.ajol.info/index.php/az/article/view/154565
- Description: A description of gametogenesis in the panga Pferogymnus laniarius, a common endemic seabream species inhabiting the Agulhas Bank, South Africa, is presented. After sexual maturity, oogenesis and spermatogenesis continued throughout the year and were found to be similar to these processes in other seabream species and teleosts in general. Analysis of maturity data over the past two decades revealed a significant change in both age and size-at-maturity, a response to fishing pressure.
- Full Text:
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446930 , vital:74571 , https://www.ajol.info/index.php/az/article/view/154565
- Description: A description of gametogenesis in the panga Pferogymnus laniarius, a common endemic seabream species inhabiting the Agulhas Bank, South Africa, is presented. After sexual maturity, oogenesis and spermatogenesis continued throughout the year and were found to be similar to these processes in other seabream species and teleosts in general. Analysis of maturity data over the past two decades revealed a significant change in both age and size-at-maturity, a response to fishing pressure.
- Full Text:
Apparent range expansion of the redbilled quelea Quelea quelea in the Eastern Cape Province of South Africa
- Authors: Whittington-Jones, C A
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448426 , vital:74729 , https://doi.org/10.1080/00306525.1997.9639720
- Description: Distribution records obtained from the South African Bird Atlas Project (SABAP) and from published literature show that the known distribution of Redbilled Quelea in the Eastern Cape has changed dramatically over the last century. Increased search effort following the initiation of SABAP may explain the range expansion, but changes in agricultural practice have probably been a contributing factor.
- Full Text:
- Authors: Whittington-Jones, C A
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448426 , vital:74729 , https://doi.org/10.1080/00306525.1997.9639720
- Description: Distribution records obtained from the South African Bird Atlas Project (SABAP) and from published literature show that the known distribution of Redbilled Quelea in the Eastern Cape has changed dramatically over the last century. Increased search effort following the initiation of SABAP may explain the range expansion, but changes in agricultural practice have probably been a contributing factor.
- Full Text:
Book Review: 1001 activities in environmental education
- Authors: Janse van Rensberg, Eureta
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438683 , vital:73490 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137449"
- Description: Book Title. 1001 activities in environmental educa-tion (1997). Book Author. Nico Allers. Publisher. Kamel eon Publishers, Vereeniging
- Full Text:
- Authors: Janse van Rensberg, Eureta
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438683 , vital:73490 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137449"
- Description: Book Title. 1001 activities in environmental educa-tion (1997). Book Author. Nico Allers. Publisher. Kamel eon Publishers, Vereeniging
- Full Text:
Catalytic behavior of osmium (II), rhodium (III) and ruthenium (II) Phthalocyanines towards the electrooxidation of cysteine on glassy carbon electrodes
- Sekota, Mantoa, Nyokong, Tebello
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
Ecology and genetics of hybrid zones in the southern African Pycnonotus bulbul species complex
- Lloyd, Penn, Craig, Adrian J F K, Hulley, Patrick E, Essop, M Faadiel, Bloomer, Paulette, Crowe, Timothy M
- Authors: Lloyd, Penn , Craig, Adrian J F K , Hulley, Patrick E , Essop, M Faadiel , Bloomer, Paulette , Crowe, Timothy M
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447801 , vital:74675 , https://doi.org/10.1080/00306525.1997.9639720
- Description: The closely related Blackeyed Bulbul Pycnonotus barbatus, Cape Bulbul P. capensis and Redeyed Bulbul P. nigricans have parapatric to locally sympatric distributions within southern Africa. Extensive hybridization along narrow transition zones between each of the three species pairs is described in a region of the Eastern Cape province, South Africa. The transition zones coincide with ecotones between different vegetation types, which in turn follow escarpments or mountain ranges. The lack of population density depressions within the hybrid zones, together with the variability of the hybrids, suggests the hybrids are viable. Sharp step clines in various phenotypic characters are described across the P. barbatus/P. nigricans hybrid zone. A mtDNA analysis found evidence of possible introgression between P. barbatus and P. capensis. All eight P. barbatus x P. nigricans hybrids analysed possessed P. barbatus mtDNA, suggesting the existence of either positive assortative mating or strong directional selection, but our data are unable to distinguish which.
- Full Text:
- Authors: Lloyd, Penn , Craig, Adrian J F K , Hulley, Patrick E , Essop, M Faadiel , Bloomer, Paulette , Crowe, Timothy M
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447801 , vital:74675 , https://doi.org/10.1080/00306525.1997.9639720
- Description: The closely related Blackeyed Bulbul Pycnonotus barbatus, Cape Bulbul P. capensis and Redeyed Bulbul P. nigricans have parapatric to locally sympatric distributions within southern Africa. Extensive hybridization along narrow transition zones between each of the three species pairs is described in a region of the Eastern Cape province, South Africa. The transition zones coincide with ecotones between different vegetation types, which in turn follow escarpments or mountain ranges. The lack of population density depressions within the hybrid zones, together with the variability of the hybrids, suggests the hybrids are viable. Sharp step clines in various phenotypic characters are described across the P. barbatus/P. nigricans hybrid zone. A mtDNA analysis found evidence of possible introgression between P. barbatus and P. capensis. All eight P. barbatus x P. nigricans hybrids analysed possessed P. barbatus mtDNA, suggesting the existence of either positive assortative mating or strong directional selection, but our data are unable to distinguish which.
- Full Text:
First-row transition metal phthalocyanines as catalysts for water electrolysis
- Chebotareva, Natalia, Nyokong, Tebello
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293391 , vital:57081 , xlink:href="https://doi.org/10.1016/S0013-4686(97)00033-9"
- Description: Modification of carbon electrodes with first row transition metal phthalocyanines results in the lowering of the potentials needed for water electrolysis in basic media, by 600 to 700 mV when compared to unmodified carbon electrodes. Nickel(II), cobalt(II) and iron(II) phthalocyanines show higher catalytic activity than zinc(II), manganese(II), copper(II) and metal free phthalocyanines.
- Full Text:
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293391 , vital:57081 , xlink:href="https://doi.org/10.1016/S0013-4686(97)00033-9"
- Description: Modification of carbon electrodes with first row transition metal phthalocyanines results in the lowering of the potentials needed for water electrolysis in basic media, by 600 to 700 mV when compared to unmodified carbon electrodes. Nickel(II), cobalt(II) and iron(II) phthalocyanines show higher catalytic activity than zinc(II), manganese(II), copper(II) and metal free phthalocyanines.
- Full Text:
Glandular trichomes on the exotic Solanum sisymbriifolium Lamarck (Solanaceae): effective deterrents against an indigenous South African herbivore
- Hill, Martin P, Hulley, Patrick E, Allsopp, J, van Harmelen, G
- Authors: Hill, Martin P , Hulley, Patrick E , Allsopp, J , van Harmelen, G
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451413 , vital:75047 , https://hdl.handle.net/10520/AJA10213589_152
- Description: An examination of the leaves of several native and exotic Solanum species revealed that they all possessed glandular and non-glandular trichomes. The density of glandular trichomes was, however, very much lower on the leaves of the indigenous species than on the leaves of a weed species, Solanum sisymbriifolium Lamarck, and two other South American Solanum species. This difference could have contributed to the depauperate faunas supported by the exotic species. The morphology and behaviour of an indigenous Solanum-feeding tortoise beetle, Conchyloctenia tigrina Oliver (Coleoptera: Chrysomelidae), and a South American tortoise beetle, Gratiana spadicea (IQug) (Coleoptera: Chrysomelidae), were compared. The study revealed that while the exudate produced by the glandular trichomes afforded S. sisymbriifolium a level of resistance to C. tigrina, it is probably only one of the factors limiting the recruitment of indigenous herbivores onto S. sisymbriifolium.
- Full Text:
- Authors: Hill, Martin P , Hulley, Patrick E , Allsopp, J , van Harmelen, G
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451413 , vital:75047 , https://hdl.handle.net/10520/AJA10213589_152
- Description: An examination of the leaves of several native and exotic Solanum species revealed that they all possessed glandular and non-glandular trichomes. The density of glandular trichomes was, however, very much lower on the leaves of the indigenous species than on the leaves of a weed species, Solanum sisymbriifolium Lamarck, and two other South American Solanum species. This difference could have contributed to the depauperate faunas supported by the exotic species. The morphology and behaviour of an indigenous Solanum-feeding tortoise beetle, Conchyloctenia tigrina Oliver (Coleoptera: Chrysomelidae), and a South American tortoise beetle, Gratiana spadicea (IQug) (Coleoptera: Chrysomelidae), were compared. The study revealed that while the exudate produced by the glandular trichomes afforded S. sisymbriifolium a level of resistance to C. tigrina, it is probably only one of the factors limiting the recruitment of indigenous herbivores onto S. sisymbriifolium.
- Full Text:
Management education and training
- Authors: Amos, Trevor L , Quinn, Lynn
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270902 , vital:54490 , xlink:href="https://hdl.handle.net/10520/AJA10113487_559"
- Description: The paper outlines the role of language in leaming and cognitive development and argues that management education and training needs to be integrated with language development to enable students to cope with the demands made of them at university as well as with those of careers in the business world. An integrated language developmEint project developed by the Depanment of Management and academic language practitioners at Rhodes Uhlvetsity is descriptionbed and suggestions are outlined as to how university Management departments can integrate language development in their mainstream teaching.
- Full Text:
- Authors: Amos, Trevor L , Quinn, Lynn
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270902 , vital:54490 , xlink:href="https://hdl.handle.net/10520/AJA10113487_559"
- Description: The paper outlines the role of language in leaming and cognitive development and argues that management education and training needs to be integrated with language development to enable students to cope with the demands made of them at university as well as with those of careers in the business world. An integrated language developmEint project developed by the Depanment of Management and academic language practitioners at Rhodes Uhlvetsity is descriptionbed and suggestions are outlined as to how university Management departments can integrate language development in their mainstream teaching.
- Full Text:
Metallophthalocyanine catalysed electroreduction of nitrate and nitrite ions in alkaline media
- Chebotareva, Natalia, Nyokong, Tebello
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293301 , vital:57073 , xlink:href="https://doi.org/10.1023/A:1018466021838"
- Description: Copper, cadmium, lead and bismuth (> 5 μg ml−1) are determined by adsorptive cathodic stripping voltammetry (AdCSV) on a mercury film glassy carbon electrode, using catechol, 4-methylcatechol, 4-t-butylcatechol and resorcinol as complexing ligands. Complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed a different behaviour from the other three metals in that the highest current response was observed with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper.
- Full Text: false
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293301 , vital:57073 , xlink:href="https://doi.org/10.1023/A:1018466021838"
- Description: Copper, cadmium, lead and bismuth (> 5 μg ml−1) are determined by adsorptive cathodic stripping voltammetry (AdCSV) on a mercury film glassy carbon electrode, using catechol, 4-methylcatechol, 4-t-butylcatechol and resorcinol as complexing ligands. Complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed a different behaviour from the other three metals in that the highest current response was observed with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper.
- Full Text: false
Multivariate analysis of honeybee populations, Apis mellifera Linnaeus (Hymenoptera: Apidae), from western central Africa morphometries and pheromones
- Radloff, Sarah E, Hepburn, H Randall
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451963 , vital:75091 , https://hdl.handle.net/10520/AJA10213589_298
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations along a transect through three ecological-climatological zones in Cameroon. There are three distinct homogeneous populations and two zones of hybridization. These bees are designated as A. m. adansollii Latreille whose area of distribution is intruded by an A. m. montieola-like montane group of bees and a third group, A. m. jemertitica Ruttner. The delineation of the hybrid zones is supported by intercolonial variance spectra and these significant asymmetries are coincident with transitions between the ecological-climatological zones.
- Full Text:
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451963 , vital:75091 , https://hdl.handle.net/10520/AJA10213589_298
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations along a transect through three ecological-climatological zones in Cameroon. There are three distinct homogeneous populations and two zones of hybridization. These bees are designated as A. m. adansollii Latreille whose area of distribution is intruded by an A. m. montieola-like montane group of bees and a third group, A. m. jemertitica Ruttner. The delineation of the hybrid zones is supported by intercolonial variance spectra and these significant asymmetries are coincident with transitions between the ecological-climatological zones.
- Full Text:
Multivariate analysis of honeybees, Apis mellifera Linnaeus (Hymenoptera: Apidae), of the Horn of Africa
- Radloff, Sarah E, Hepburn, H Randall
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451987 , vital:75093 , https://hdl.handle.net/10520/AJA10213589_154
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to delineate the honeybee populations of the Horn of Africa. Four discrete and statistically homogeneous populations were identified: A. m. jemenitica Ruttner, A. m. bandasii Mogga, A. m. sudanensis Rashad in Ethiopia and an unclassified group in southwestern Somalia. Areas of high intercolonial variance are interpreted as zones of hybridization between the populations.
- Full Text:
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451987 , vital:75093 , https://hdl.handle.net/10520/AJA10213589_154
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to delineate the honeybee populations of the Horn of Africa. Four discrete and statistically homogeneous populations were identified: A. m. jemenitica Ruttner, A. m. bandasii Mogga, A. m. sudanensis Rashad in Ethiopia and an unclassified group in southwestern Somalia. Areas of high intercolonial variance are interpreted as zones of hybridization between the populations.
- Full Text:
Photosensitization reactions of neodymium, dysprosium and lutetium diphthalocyanine
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:57084 , xlink:href="https://doi.org/10.1016/S0277-5387(97)00045-4"
- Description: Photolysis, using a visible radiation, of diphthalocyanine complexes of NdIII, DyIII and LuIII ([Pc(−2)NdIIIPc(−2)]−, [Pc(−2)DyIIIPc(−2)]− and [Pc(−2)LuIIIPc(−2)]−, respectively) in the presence of pentachlorophenol (PCP) or SO2 results in the one-electron oxidation of the diphthalocyanine species to Pc(−1)NdIIIPc(−2), Pc(−1)DyIIIPc(−2) and Pc(−2)LuIIIPc(−2), respectively. The PCP is reductively dechlorinated to tetra- and trichlorophenols. The quantum yields for the photosensitization reactions are of the order 10−4.
- Full Text:
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:57084 , xlink:href="https://doi.org/10.1016/S0277-5387(97)00045-4"
- Description: Photolysis, using a visible radiation, of diphthalocyanine complexes of NdIII, DyIII and LuIII ([Pc(−2)NdIIIPc(−2)]−, [Pc(−2)DyIIIPc(−2)]− and [Pc(−2)LuIIIPc(−2)]−, respectively) in the presence of pentachlorophenol (PCP) or SO2 results in the one-electron oxidation of the diphthalocyanine species to Pc(−1)NdIIIPc(−2), Pc(−1)DyIIIPc(−2) and Pc(−2)LuIIIPc(−2), respectively. The PCP is reductively dechlorinated to tetra- and trichlorophenols. The quantum yields for the photosensitization reactions are of the order 10−4.
- Full Text:
Redescription of three species of the genus Platypleura Amyot and Serville 1843 (Hemiptera Cicadidae)
- Authors: Villet, Martin H
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453827 , vital:75290 , https://doi.org/10.1080/03946975.1997.10539345
- Description: The type material of three platypleurine cicadas described by GERMAR (1834), Platypleura divisa, P. hirtipennis and P. plumosa, have been rediscovered and are redescribed to clarify their identity. Notes on their biology and biogeography are included.
- Full Text:
- Authors: Villet, Martin H
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453827 , vital:75290 , https://doi.org/10.1080/03946975.1997.10539345
- Description: The type material of three platypleurine cicadas described by GERMAR (1834), Platypleura divisa, P. hirtipennis and P. plumosa, have been rediscovered and are redescribed to clarify their identity. Notes on their biology and biogeography are included.
- Full Text:
Reflecting on socially transformative environmental literacy for Lesotho
- Mokuku, Tsepo, Lotz-Sisitka, Heila
- Authors: Mokuku, Tsepo , Lotz-Sisitka, Heila
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438769 , vital:73498 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137444"
- Description: This paper is an attempt to clarify the concept of environmental literacy from a socially transformative orientation. It resulted from our ongoing reflection on a conceptual framework in and for a three-year research project on education for environmental literacy within the integrated science curriculum in Lesotho.
- Full Text:
- Authors: Mokuku, Tsepo , Lotz-Sisitka, Heila
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438769 , vital:73498 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137444"
- Description: This paper is an attempt to clarify the concept of environmental literacy from a socially transformative orientation. It resulted from our ongoing reflection on a conceptual framework in and for a three-year research project on education for environmental literacy within the integrated science curriculum in Lesotho.
- Full Text:
Substituted catechols as complexing agents for the determination of bismuth, lead, copper and cadmium by adsorptive stripping voltammetry
- Limson, Janice L, Nyokong, Tebello
- Authors: Limson, Janice L , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293311 , vital:57074 , xlink:href="https://doi.org/10.1016/S0003-2670(96)00585-5"
- Description: Copper, cadmium, lead and bismuth (> 5 μg ml−1) are determined by adsorptive cathodic stripping voltammetry (AdCSV) on a mercury film glassy carbon electrode, using catechol, 4-methylcatechol, 4-t-butylcatechol and resorcinol as complexing ligands. Complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed a different behaviour from the other three metals in that the highest current response was observed with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper.
- Full Text:
- Authors: Limson, Janice L , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293311 , vital:57074 , xlink:href="https://doi.org/10.1016/S0003-2670(96)00585-5"
- Description: Copper, cadmium, lead and bismuth (> 5 μg ml−1) are determined by adsorptive cathodic stripping voltammetry (AdCSV) on a mercury film glassy carbon electrode, using catechol, 4-methylcatechol, 4-t-butylcatechol and resorcinol as complexing ligands. Complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed a different behaviour from the other three metals in that the highest current response was observed with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper.
- Full Text:
The cicada genus Stagira Stål 1861 (Homoptera Tibicinidae) systematic revision
- Authors: Villet, Martin H
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453903 , vital:75297 , https://doi.org/10.1080/03946975.1997.10539347
- Description: The cicada genus Stagira Stål 1861 is redescribed and re-vised. S. sanguinea Distant 1920 n. syn. and S. rufi-costata Distant 1920 n. syn. are synonymized with S. seg-mentaria Karsch ! 890, while S. aethlius (Walker 1850) n. stat. and S. acrida (Walker 1850) n. stat. are removed from the synonymy of S. simplex (Germar 1834) and restored to specific status. An additional 32 new species are described and a key is provided to the males of the genus. Stagira is endemic to the eastern tropical transitional area of south-ern Africa, and has occupied a variety of habitats, from xe-ric scrub to grassland savanna to forest. It forms a group with the South African genera Xosopsaltria Kirkaldy 1904, Tettigomyia Amyot and Serville 1843 and Bavea Distant 1905.
- Full Text:
- Authors: Villet, Martin H
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453903 , vital:75297 , https://doi.org/10.1080/03946975.1997.10539347
- Description: The cicada genus Stagira Stål 1861 is redescribed and re-vised. S. sanguinea Distant 1920 n. syn. and S. rufi-costata Distant 1920 n. syn. are synonymized with S. seg-mentaria Karsch ! 890, while S. aethlius (Walker 1850) n. stat. and S. acrida (Walker 1850) n. stat. are removed from the synonymy of S. simplex (Germar 1834) and restored to specific status. An additional 32 new species are described and a key is provided to the males of the genus. Stagira is endemic to the eastern tropical transitional area of south-ern Africa, and has occupied a variety of habitats, from xe-ric scrub to grassland savanna to forest. It forms a group with the South African genera Xosopsaltria Kirkaldy 1904, Tettigomyia Amyot and Serville 1843 and Bavea Distant 1905.
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The study of the interactions of cobalt (II) tetrasulfophthalocyanine with cysteine and histidine
- Sekota, Mantoa, Nyokong, Tebello
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293458 , vital:57087 , xlink:href="https://doi.org/10.1016/S0277-5387(97)00096-X"
- Description: Kinetics for the interaction of cobalt(II) tetrasulfophthalocyanine ([CoIITSPc]4−, Pc(−2) = phthalocyanine dianion) with the amino acids, histidine and cysteine, in pH 7.2 phosphate buffer were studied. The rates were found to be first order in both the [CoIITSPc]4− and the amino acid. The formation of the [CoIIITSPc]3− species in the presence of histidine occurred with a rate constant of 0.16 dm3 mol−s−1, whereas the formation of the [CoITSPc]5− species in the presence of cysteine gave a rate constant of 2.2 dm3 mol−1.
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- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293458 , vital:57087 , xlink:href="https://doi.org/10.1016/S0277-5387(97)00096-X"
- Description: Kinetics for the interaction of cobalt(II) tetrasulfophthalocyanine ([CoIITSPc]4−, Pc(−2) = phthalocyanine dianion) with the amino acids, histidine and cysteine, in pH 7.2 phosphate buffer were studied. The rates were found to be first order in both the [CoIITSPc]4− and the amino acid. The formation of the [CoIIITSPc]3− species in the presence of histidine occurred with a rate constant of 0.16 dm3 mol−s−1, whereas the formation of the [CoITSPc]5− species in the presence of cysteine gave a rate constant of 2.2 dm3 mol−1.
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Towards sustainable conversation: Developing environmental education processes
- Authors: Le Roux, Kim
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389884 , vital:68492 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137446"
- Description: This paper highlights the importance of seeing environmental education as a process and considers the value of conversation and storytelling in environmental education processes. These processes are explored from a post-structural perspective within the context of the writer's own involvement in supporting environmental education processes.
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- Authors: Le Roux, Kim
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389884 , vital:68492 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137446"
- Description: This paper highlights the importance of seeing environmental education as a process and considers the value of conversation and storytelling in environmental education processes. These processes are explored from a post-structural perspective within the context of the writer's own involvement in supporting environmental education processes.
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Troubled waters in south-western New Georgia, Solomon Islands: Is codification of the commons a viable avenue for resource use regularisation
- Authors: Shankar, Aswani
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440061 , vital:73732
- Description: In recent decades there has been a growing interest in indigenous sea tenure institutions and their possible role in establishing a framework for sustainable resource use and conservation. Yet the feasibility of these institutions to cope with social and economic changes have been seldom explored. In this paper a case study is presented where internal deregularisation of the ‘commons’ is the result of existing socio-cultural principles combined with outside influences. Two territorial models are compared to elucidate emerging internal instabilities of sea tenure institutions and possible ways to correct existing problems. The codification of the commons is suggested here as a possible measure to strengthen indigenous common property regimes.
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- Authors: Shankar, Aswani
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440061 , vital:73732
- Description: In recent decades there has been a growing interest in indigenous sea tenure institutions and their possible role in establishing a framework for sustainable resource use and conservation. Yet the feasibility of these institutions to cope with social and economic changes have been seldom explored. In this paper a case study is presented where internal deregularisation of the ‘commons’ is the result of existing socio-cultural principles combined with outside influences. Two territorial models are compared to elucidate emerging internal instabilities of sea tenure institutions and possible ways to correct existing problems. The codification of the commons is suggested here as a possible measure to strengthen indigenous common property regimes.
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Use of cobalt (II) phthalocyanine to improve the sensitivity and stability of glassy carbon electrodes for the detection of cresols, chlorophenols and phenol
- Mafatle, Tsukutlane J, Nyokong, Tebello
- Authors: Mafatle, Tsukutlane J , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293335 , vital:57076 , xlink:href="https://doi.org/10.1016/S0003-2670(97)00464-9"
- Description: A cobalt(II) phthalocyanine-modified glassy carbon electrode (CoPc-GCE) was used for the detection of o-, m- and p-cresols, and of 2-chlorophenol, 4-chlorophenol and phenol. Modification of the glassy carbon electrode with CoPc increases the oxidation currents of these species and increases the stability of the electrode. CoPc-GCE showed less fouling by the oxidation products of these compounds than the unmodified GCE. Comparison of some first row transition metal phthalocyanines showed the following trend for the enhancement of the currents for the oxidation of cresols and phenols: Co(II)Pc > Mn(II)Pc > Fe(II)Pc > Ni(II)Pc > Cu(II)Pc > H2Pc > Zn(II)Pc > GCE. When [Co(II)TSPc]4− (TSPc=tetrasulfo Pc) was added to aqueous solutions containing the cresols and phenols, an enhancement of the oxidation currents was also observed.
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- Authors: Mafatle, Tsukutlane J , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293335 , vital:57076 , xlink:href="https://doi.org/10.1016/S0003-2670(97)00464-9"
- Description: A cobalt(II) phthalocyanine-modified glassy carbon electrode (CoPc-GCE) was used for the detection of o-, m- and p-cresols, and of 2-chlorophenol, 4-chlorophenol and phenol. Modification of the glassy carbon electrode with CoPc increases the oxidation currents of these species and increases the stability of the electrode. CoPc-GCE showed less fouling by the oxidation products of these compounds than the unmodified GCE. Comparison of some first row transition metal phthalocyanines showed the following trend for the enhancement of the currents for the oxidation of cresols and phenols: Co(II)Pc > Mn(II)Pc > Fe(II)Pc > Ni(II)Pc > Cu(II)Pc > H2Pc > Zn(II)Pc > GCE. When [Co(II)TSPc]4− (TSPc=tetrasulfo Pc) was added to aqueous solutions containing the cresols and phenols, an enhancement of the oxidation currents was also observed.
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