Bycatch and discarding in the South African demersal trawl fishery
- Walmsley, Sarah A, Leslie, Rob W, Sauer, Warwick H H
- Authors: Walmsley, Sarah A , Leslie, Rob W , Sauer, Warwick H H
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123944 , vital:35518 , https://doi.10.1016/j.fishres.2007.03.002
- Description: Observers aboard commercial trawlers collected data on the total catch composition of 614 and 479 hauls made by vessels operating off the south and west coasts of South Africa, respectively. On the south coast, four fishing areas were identified on the basis of target species and fishing depth. On the west coast, hauls were separated into those targeting hake Merluccius spp. in four depth ranges (0–300, 301–400, 401–500, and >500 m) and those targeting monkfish Lophius vomerinus. For each area, the catch composition was calculated and the species assemblages were investigated using cluster analysis and multi-dimensional scaling. Finally, for each coast, the weight of fish discarded annually was estimated. On the south coast, although hake dominated, between 21% and 47% of the catch was not hake, depending on the fishing area. In comparison, hake dominated west coast catches, the proportion of hake increasing with depth. For each fishery investigated, approximately 90% of the catch was processed and landed. However, estimates of annual discards indicate that the south and west coast fisheries may annually discard 9000 or 10,000 t and 17,000 or 25,000 t, of undersized and unutilizable fish and offal, respectively, depending on the estimation method used. When developing strategies to limit or enhance utilization of bycatch, cognisance should be taken of the differences in catch composition between the south and west coasts and of the importance of bycatch revenue to south coast fishing companies.
- Full Text:
- Date Issued: 2007
- Authors: Walmsley, Sarah A , Leslie, Rob W , Sauer, Warwick H H
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123944 , vital:35518 , https://doi.10.1016/j.fishres.2007.03.002
- Description: Observers aboard commercial trawlers collected data on the total catch composition of 614 and 479 hauls made by vessels operating off the south and west coasts of South Africa, respectively. On the south coast, four fishing areas were identified on the basis of target species and fishing depth. On the west coast, hauls were separated into those targeting hake Merluccius spp. in four depth ranges (0–300, 301–400, 401–500, and >500 m) and those targeting monkfish Lophius vomerinus. For each area, the catch composition was calculated and the species assemblages were investigated using cluster analysis and multi-dimensional scaling. Finally, for each coast, the weight of fish discarded annually was estimated. On the south coast, although hake dominated, between 21% and 47% of the catch was not hake, depending on the fishing area. In comparison, hake dominated west coast catches, the proportion of hake increasing with depth. For each fishery investigated, approximately 90% of the catch was processed and landed. However, estimates of annual discards indicate that the south and west coast fisheries may annually discard 9000 or 10,000 t and 17,000 or 25,000 t, of undersized and unutilizable fish and offal, respectively, depending on the estimation method used. When developing strategies to limit or enhance utilization of bycatch, cognisance should be taken of the differences in catch composition between the south and west coasts and of the importance of bycatch revenue to south coast fishing companies.
- Full Text:
- Date Issued: 2007
Camphor-derived chiral auxiliaries: a synthetic, mechanistic and computational study
- Authors: Duggan, Andrew Robert
- Date: 2007
- Subjects: Camphor Chirality Asymmetric synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4415 , http://hdl.handle.net/10962/d1006772
- Description: A broadly based approach has been undertaken to the development and use of camphor derivatives as chiral auxiliaries in asymmetric synthesis – an approach which has embraced synthetic, mechanistic and computational studies. The unambiguous characterization of mono- and dihydroxy-derivatives, obtained by reduction of chiral camphor ether dimers, has been achieved through detailed one- and two-dimensional NMR spectroscopic analysis. The resulting data has been used to establish both the regio- and stereochemistry of the hydroxyl groups. A camphor-derived cyclic iminolactone has been shown to provide a convenient platform for the synthesis of chiral α-amino acids, stereoselective monoalkylation of the iminolactone affording a range of products in yields of 52 - 65 % with up to 85 % d.e. The attempted development of chiral bifunctional Morita-Baylis-Hillman substrates has revealed an unexpected equilibration between isomeric bornane 2,3-diol monoacrylates via acid-catalysed intramolecular transesterification. A detailed [superscript 1]H NMR-based kinetic study of the rearrangement in various media and at various temperatures has permitted the determination of the kinetic and thermodynamic parameters. A computational study at the DFT level has been used to explore the potential energy surfaces of the acid-catalysed and uncatalysed transesterification of the monoacrylate esters. The theoretical data supports the involvement of cyclic intermediates and has provided a rational basis for predicting the favoured reaction pathways. Novel camphor-derived phenyl sulfonate esters and N-adamantylsulfonamides have been synthesised for use as chiral auxiliaries in the Morita-Baylis-Hillman reaction. Modeling at the Molecular Mechanics level has provided useful insights into possible conformational constraints and an adamantyl sulfonate auxiliary has been successfully used in the stereoselective synthesis of a range of products, generally in excellent yield and with up to 95 % d.e.
- Full Text:
- Date Issued: 2007
- Authors: Duggan, Andrew Robert
- Date: 2007
- Subjects: Camphor Chirality Asymmetric synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4415 , http://hdl.handle.net/10962/d1006772
- Description: A broadly based approach has been undertaken to the development and use of camphor derivatives as chiral auxiliaries in asymmetric synthesis – an approach which has embraced synthetic, mechanistic and computational studies. The unambiguous characterization of mono- and dihydroxy-derivatives, obtained by reduction of chiral camphor ether dimers, has been achieved through detailed one- and two-dimensional NMR spectroscopic analysis. The resulting data has been used to establish both the regio- and stereochemistry of the hydroxyl groups. A camphor-derived cyclic iminolactone has been shown to provide a convenient platform for the synthesis of chiral α-amino acids, stereoselective monoalkylation of the iminolactone affording a range of products in yields of 52 - 65 % with up to 85 % d.e. The attempted development of chiral bifunctional Morita-Baylis-Hillman substrates has revealed an unexpected equilibration between isomeric bornane 2,3-diol monoacrylates via acid-catalysed intramolecular transesterification. A detailed [superscript 1]H NMR-based kinetic study of the rearrangement in various media and at various temperatures has permitted the determination of the kinetic and thermodynamic parameters. A computational study at the DFT level has been used to explore the potential energy surfaces of the acid-catalysed and uncatalysed transesterification of the monoacrylate esters. The theoretical data supports the involvement of cyclic intermediates and has provided a rational basis for predicting the favoured reaction pathways. Novel camphor-derived phenyl sulfonate esters and N-adamantylsulfonamides have been synthesised for use as chiral auxiliaries in the Morita-Baylis-Hillman reaction. Modeling at the Molecular Mechanics level has provided useful insights into possible conformational constraints and an adamantyl sulfonate auxiliary has been successfully used in the stereoselective synthesis of a range of products, generally in excellent yield and with up to 95 % d.e.
- Full Text:
- Date Issued: 2007
Catalytic activities of metallophthalocyanines towards detection and transformation of pollutants
- Authors: Agboola, Bolade Oyeyinka
- Date: 2007
- Subjects: Phthalocyanines Electrochemistry Pollutants -- Biodegradation Pollutants -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4427 , http://hdl.handle.net/10962/d1006922
- Description: Syntheses, spectral, electrochemical and spectroelectrochemical studies of new thiol-derivatised MPc complexes were satisfactorily carried out. For the first time, spectroelectrochemistry gave evidence for the formation of Ni²⁺/Ni⁺ process in a NiPc complex. Significant insights as to the nature of Fe⁺Pc and Ni⁺Pc spectra were obtained. Transformations of chlorophenols using chemical and photochemical methods are presented. For cobalt tetrasulphophthalocyanine catalysed oxidation of chlorophenols using hydrogen peroxide as the oxidant, types of oxidation products formed depended on the solvent conditions. Photolysis of aqueous solutions of chlorophenols in the presence of immobilised non-transition metal phthalocyanine photosensitisers onto Amerlite® was carried out. For the first time, MPcS[subscript mix] complexes were immobilised on Amberlite® for use in heterogeneous photocatalysis. Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The generation of singlet oxygen (¹O₂) by these immobilised MPc photosensitisers was found to play a major role in their photoactivities. Modifications of gold electrodes with the newly synthesised thiol-derivatised MPc complexes via electropolymerisation and SAM techniques are presented. Cyclic voltammetry, impedance spectroscopy (NiPcs only) and spectroelectrochemical techniques (NiPcs only) confirmed that the complexes formed films on gold electrodes. Stable and well packed SAM films as evidenced by the voltammetric characterisation were obtained. For the first time, optimisation of the time for SAM formation based on CV technique was studied. First example of a formation of MnPc-SAM was achieved. Catalytic activities of the NiPc towards chlorophenol depended on the nature of the NiPc in the polymer films and also anti-fouling ability of the films depended on polymer film thickness. The FeTBMPc polymer modified gold electrode showed the best catalytic activity in terms of peak potential, E[subscript p] when compared to reported work in literature for nitrate electrooxidation. Cyclic voltammetry and spectroscopy studies showed that the CoPcs, FePcs and NiPcs catalysed nitrite oxidation involve 2 electrons in total while that of McPcs involve 1 electron. Better catalytic performance towards sulphite electrooxidation were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak while the NiPcs which did not show metal based oxidation reaction performed less.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade Oyeyinka
- Date: 2007
- Subjects: Phthalocyanines Electrochemistry Pollutants -- Biodegradation Pollutants -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4427 , http://hdl.handle.net/10962/d1006922
- Description: Syntheses, spectral, electrochemical and spectroelectrochemical studies of new thiol-derivatised MPc complexes were satisfactorily carried out. For the first time, spectroelectrochemistry gave evidence for the formation of Ni²⁺/Ni⁺ process in a NiPc complex. Significant insights as to the nature of Fe⁺Pc and Ni⁺Pc spectra were obtained. Transformations of chlorophenols using chemical and photochemical methods are presented. For cobalt tetrasulphophthalocyanine catalysed oxidation of chlorophenols using hydrogen peroxide as the oxidant, types of oxidation products formed depended on the solvent conditions. Photolysis of aqueous solutions of chlorophenols in the presence of immobilised non-transition metal phthalocyanine photosensitisers onto Amerlite® was carried out. For the first time, MPcS[subscript mix] complexes were immobilised on Amberlite® for use in heterogeneous photocatalysis. Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The generation of singlet oxygen (¹O₂) by these immobilised MPc photosensitisers was found to play a major role in their photoactivities. Modifications of gold electrodes with the newly synthesised thiol-derivatised MPc complexes via electropolymerisation and SAM techniques are presented. Cyclic voltammetry, impedance spectroscopy (NiPcs only) and spectroelectrochemical techniques (NiPcs only) confirmed that the complexes formed films on gold electrodes. Stable and well packed SAM films as evidenced by the voltammetric characterisation were obtained. For the first time, optimisation of the time for SAM formation based on CV technique was studied. First example of a formation of MnPc-SAM was achieved. Catalytic activities of the NiPc towards chlorophenol depended on the nature of the NiPc in the polymer films and also anti-fouling ability of the films depended on polymer film thickness. The FeTBMPc polymer modified gold electrode showed the best catalytic activity in terms of peak potential, E[subscript p] when compared to reported work in literature for nitrate electrooxidation. Cyclic voltammetry and spectroscopy studies showed that the CoPcs, FePcs and NiPcs catalysed nitrite oxidation involve 2 electrons in total while that of McPcs involve 1 electron. Better catalytic performance towards sulphite electrooxidation were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak while the NiPcs which did not show metal based oxidation reaction performed less.
- Full Text:
- Date Issued: 2007
Causes of persistent rural poverty in Thika district of Kenya, c.1953-2000
- Authors: Kinyanjui, Felistus Kinuna
- Date: 2007
- Subjects: Poverty -- Kenya -- History Rural poor -- Kenya -- History Agriculture -- Kenya -- History Kenya -- History Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2547 , http://hdl.handle.net/10962/d1002399
- Description: This study investigates the causes of poverty among the residents of Thika District in Kenya over the period 1953-2000. Using the articulation of modes of production perspective, the study traces the dynamics of poverty to the geography, history and politics of Thika District. The thrust of the argument is that livelihoods in the district changed during the period under investigation, but not necessarily for the better. Landlessness, collapse of the coffee industry, intergenerational poverty, and the ravages of diseases (particularly of HIV/AIDS) are analysed. This leads to the conclusion that causes of poverty in Thika District during the period under examination were complex as one form of deprivation led to another. The study established that poverty in Thika District during the period under review was a product of a process of exclusion from the centre of political power and appropriation. While race was the basis for allocation of public resources in colonial Kenya, ethnicity has dominated the independence period. Consequently, one would have expected the residents of Thika District, the home of Kenya’s first president, Mzee Jomo Kenyatta, to have benefited inordinately from public resources during his rule. Kenyatta’s administration, however, mainly benefited the Kikuyu elite. The study therefore demonstrates that during the period under examination, the Kikuyu, like any other Kenyan community, were a heterogeneous group whose differences were accentuated by class relations. Subaltern groups in Thika District therefore benefited minimally from state patronage, just like similar groups elsewhere in rural Kenya. By the late 1970s, the level of deprivation in rural Kenya had been contained as a result of favourable prices for the country’s agricultural exports. But in the subsequent period, poverty increased under the pressures of world economic recession and slowdowns in trade. The situation was worse for Kikuyu peasants as the Second Republic of President Daniel Moi deliberately attempted undermine the Kikuyu economically. For the majority of Thika residents, this translated into further marginalisation as the Moi regime lumped them together with the Kikuyu elite who had benefitted inordinately from public resources during the Kenyatta era. This study demonstrates that no single factor can explain the prevalence of poverty in Thika District during the period under consideration. However, the poor in the district devised survival mechanisms that could be replicated elsewhere. Indeed, the dynamics of poverty in Thika District represent a microcosm not just for the broader Kenyan situation but also of rural livelihoods elsewhere in the world. The study recommends land reform and horticulture as possible ways of reducing poverty among rural communities. Further, for a successful global war on poverty there is an urgent need to have the West go beyond rhetoric and deliver on its promises to make poverty history.
- Full Text:
- Date Issued: 2007
- Authors: Kinyanjui, Felistus Kinuna
- Date: 2007
- Subjects: Poverty -- Kenya -- History Rural poor -- Kenya -- History Agriculture -- Kenya -- History Kenya -- History Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2547 , http://hdl.handle.net/10962/d1002399
- Description: This study investigates the causes of poverty among the residents of Thika District in Kenya over the period 1953-2000. Using the articulation of modes of production perspective, the study traces the dynamics of poverty to the geography, history and politics of Thika District. The thrust of the argument is that livelihoods in the district changed during the period under investigation, but not necessarily for the better. Landlessness, collapse of the coffee industry, intergenerational poverty, and the ravages of diseases (particularly of HIV/AIDS) are analysed. This leads to the conclusion that causes of poverty in Thika District during the period under examination were complex as one form of deprivation led to another. The study established that poverty in Thika District during the period under review was a product of a process of exclusion from the centre of political power and appropriation. While race was the basis for allocation of public resources in colonial Kenya, ethnicity has dominated the independence period. Consequently, one would have expected the residents of Thika District, the home of Kenya’s first president, Mzee Jomo Kenyatta, to have benefited inordinately from public resources during his rule. Kenyatta’s administration, however, mainly benefited the Kikuyu elite. The study therefore demonstrates that during the period under examination, the Kikuyu, like any other Kenyan community, were a heterogeneous group whose differences were accentuated by class relations. Subaltern groups in Thika District therefore benefited minimally from state patronage, just like similar groups elsewhere in rural Kenya. By the late 1970s, the level of deprivation in rural Kenya had been contained as a result of favourable prices for the country’s agricultural exports. But in the subsequent period, poverty increased under the pressures of world economic recession and slowdowns in trade. The situation was worse for Kikuyu peasants as the Second Republic of President Daniel Moi deliberately attempted undermine the Kikuyu economically. For the majority of Thika residents, this translated into further marginalisation as the Moi regime lumped them together with the Kikuyu elite who had benefitted inordinately from public resources during the Kenyatta era. This study demonstrates that no single factor can explain the prevalence of poverty in Thika District during the period under consideration. However, the poor in the district devised survival mechanisms that could be replicated elsewhere. Indeed, the dynamics of poverty in Thika District represent a microcosm not just for the broader Kenyan situation but also of rural livelihoods elsewhere in the world. The study recommends land reform and horticulture as possible ways of reducing poverty among rural communities. Further, for a successful global war on poverty there is an urgent need to have the West go beyond rhetoric and deliver on its promises to make poverty history.
- Full Text:
- Date Issued: 2007
Changes in fuelwood use and selection following electrification in the Bushbuckridge lowveld, South Africa
- Madubansi, Mainza, Shackleton, Charlie M
- Authors: Madubansi, Mainza , Shackleton, Charlie M
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6641 , http://hdl.handle.net/10962/d1006867
- Description: Fuelwood is the primary energy source for domestic purposes throughout the developing world, in both urban and rural environments. Due to the detrimental impacts of biomass use on human and environmental health, many governments have sought to reduce its use through provision of potentially cleaner energies, of which electricity is the dominant form. Yet there are surprisingly few studies of changes in fuelwood use following the introduction of electricity, especially in rural areas of Africa. This paper reports on a longitudinal study of fuelwood use, using identical approaches, in five rural villages in the Bushbuckridge region of South Africa, spanning the period over which electricity became widely available. Almost a decade after the introduction of electricity, over 90% of households still used fuelwood for thermal purposes, especially cooking, and the mean household consumption rates over the 11-year period had not changed, even with a policy of 6 kWh per month of free electricity. The proportion of households purchasing fuelwood had increased, probably in response to a number of factors, including (i) increased fuelwood scarcity in the local environment as reflected by increased fuelwood collection times, changes in fuelwood species preferences, and ranking of scarcity by local collectors, and (ii) increases in the price of fuelwood well below that of other fuels and the prevailing inflation rate. Overall, there was an increase in the number of species harvested over the 11-year period. The implications of these findings for rural energy provision are discussed.
- Full Text:
- Date Issued: 2007
- Authors: Madubansi, Mainza , Shackleton, Charlie M
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6641 , http://hdl.handle.net/10962/d1006867
- Description: Fuelwood is the primary energy source for domestic purposes throughout the developing world, in both urban and rural environments. Due to the detrimental impacts of biomass use on human and environmental health, many governments have sought to reduce its use through provision of potentially cleaner energies, of which electricity is the dominant form. Yet there are surprisingly few studies of changes in fuelwood use following the introduction of electricity, especially in rural areas of Africa. This paper reports on a longitudinal study of fuelwood use, using identical approaches, in five rural villages in the Bushbuckridge region of South Africa, spanning the period over which electricity became widely available. Almost a decade after the introduction of electricity, over 90% of households still used fuelwood for thermal purposes, especially cooking, and the mean household consumption rates over the 11-year period had not changed, even with a policy of 6 kWh per month of free electricity. The proportion of households purchasing fuelwood had increased, probably in response to a number of factors, including (i) increased fuelwood scarcity in the local environment as reflected by increased fuelwood collection times, changes in fuelwood species preferences, and ranking of scarcity by local collectors, and (ii) increases in the price of fuelwood well below that of other fuels and the prevailing inflation rate. Overall, there was an increase in the number of species harvested over the 11-year period. The implications of these findings for rural energy provision are discussed.
- Full Text:
- Date Issued: 2007
Changing terms and conditions of employment following transferes to the Western Cape department of health
- Authors: Roman, Richard Joseph
- Date: 2007
- Subjects: Labor laws and legislation -- South Africa -- Western Cape , Industrial relations -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10231 , http://hdl.handle.net/10948/824 , Labor laws and legislation -- South Africa -- Western Cape , Industrial relations -- South Africa -- Western Cape
- Description: This treatise describes the difficulty of changing conditions of service following transfers in terms of Section 197 of the Labour Relations Act, 66 of 1995. The Constitution of the Republic of South Africa, Act 108 of 1996, provides that ambulance services are a Provincial Legislative competence. The City of Cape Town had for many years provided ambulance services on an agency basis to the Department of Health of the Provincial Administration of the Western Cape. The impact of the constitutional provision is that those employers and employees who are performing ambulance services are not entitled anymore to perform such function. The Department of Health must take control over the ambulance services and the employees of the City of Cape Town could be transferred. The challenges facing both employers (old and new) and the trade unions to secure a transfer of the employees from the City of Cape Town to the Department of Health in terms of section 197 of the Labour Relations Act will be highlighted. It is within the context of ensuring protection of jobs whilst simultaneously effect a transfer of contracts of employment that the Labour Relations Act expressly gives various options to the parties involves in a transfer. Of the options include: • A transfer in terms of section 197(2) of the LRA where the service could be transferred from the old employer to the new employer as a going concern. This could happen without the consent of the affected employees or trade unions and collective agreements must be taken over as well, or • The new employer complies with its obligations if the transfer takes place on terms and conditions that are on the whole not less favourable to the employees what they have received by the old employer. In terms of this provision the overall package of conditions of service that was offered should not be less in comparison with that of the old employer. • The parties also have the option to negotiate a transfer agreement that could regulate the conditions of service. The focus is on the description of the conditions of service of both employers and the difficulty to persuade the trade unions to accept the Department’s conditions of service. Part of the difficulty is that the Department must obtain its mandate from the Department of the Public Service and Administration, who is also responsible for the determining of the conditions of service in the Public Service. One of the challenges is that the Department of Health cannot accommodate collective agreements of entities outside the Public Service. The City of Cape Town’s conditions of service is in the form of a collective agreement and the Labour Relations Act is very specific with the various options. These options will be discussed an analised. In conclusion recommendations are made in regard to effect a transfer of conditions of employment in terms of the Labour Relations Act to enable the Department of Health to meet its constitutional obligation.
- Full Text:
- Date Issued: 2007
- Authors: Roman, Richard Joseph
- Date: 2007
- Subjects: Labor laws and legislation -- South Africa -- Western Cape , Industrial relations -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10231 , http://hdl.handle.net/10948/824 , Labor laws and legislation -- South Africa -- Western Cape , Industrial relations -- South Africa -- Western Cape
- Description: This treatise describes the difficulty of changing conditions of service following transfers in terms of Section 197 of the Labour Relations Act, 66 of 1995. The Constitution of the Republic of South Africa, Act 108 of 1996, provides that ambulance services are a Provincial Legislative competence. The City of Cape Town had for many years provided ambulance services on an agency basis to the Department of Health of the Provincial Administration of the Western Cape. The impact of the constitutional provision is that those employers and employees who are performing ambulance services are not entitled anymore to perform such function. The Department of Health must take control over the ambulance services and the employees of the City of Cape Town could be transferred. The challenges facing both employers (old and new) and the trade unions to secure a transfer of the employees from the City of Cape Town to the Department of Health in terms of section 197 of the Labour Relations Act will be highlighted. It is within the context of ensuring protection of jobs whilst simultaneously effect a transfer of contracts of employment that the Labour Relations Act expressly gives various options to the parties involves in a transfer. Of the options include: • A transfer in terms of section 197(2) of the LRA where the service could be transferred from the old employer to the new employer as a going concern. This could happen without the consent of the affected employees or trade unions and collective agreements must be taken over as well, or • The new employer complies with its obligations if the transfer takes place on terms and conditions that are on the whole not less favourable to the employees what they have received by the old employer. In terms of this provision the overall package of conditions of service that was offered should not be less in comparison with that of the old employer. • The parties also have the option to negotiate a transfer agreement that could regulate the conditions of service. The focus is on the description of the conditions of service of both employers and the difficulty to persuade the trade unions to accept the Department’s conditions of service. Part of the difficulty is that the Department must obtain its mandate from the Department of the Public Service and Administration, who is also responsible for the determining of the conditions of service in the Public Service. One of the challenges is that the Department of Health cannot accommodate collective agreements of entities outside the Public Service. The City of Cape Town’s conditions of service is in the form of a collective agreement and the Labour Relations Act is very specific with the various options. These options will be discussed an analised. In conclusion recommendations are made in regard to effect a transfer of conditions of employment in terms of the Labour Relations Act to enable the Department of Health to meet its constitutional obligation.
- Full Text:
- Date Issued: 2007
Characterisation of Human Hsj1a : an HSP40 molecular chaperone similar to Malarial Pfj4
- Authors: McNamara, Caryn
- Date: 2007
- Subjects: Heat shock proteins , Protein folding , Proteins -- Analysis , Proteins -- Structure , Plasmodium , Malaria , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4083 , http://hdl.handle.net/10962/d1007603
- Description: Protein folding, translocation, oligomeric rearrangement and degradation are vital functions to obtain correctly folded proteins in any cell. The constitutive or stress-induced members of each of the heat shock protein (Hsp) families, namely Hsp70 and Hsp40, make up the Hsp70/Hsp40 chaperone system. The Hsp40 J-domain is important for the Hsp70-Hsp40 interaction and hence function. The type-II Hsp40 proteins, Homo sapiens DnaJ 1a (Hsj1a) and Plasmodium falciparum DnaJ 4 (Pfj4), are structurally similar suggesting possible similar roles during malarial infection. This thesis has focussed on identifying whether Hsj1a and Pfj4 are functionally similar in their interaction with potential partner Hsp70 chaperones. Analysis in silico also showed Pfj4 to have a potential chaperone domain, a region resembling a ubiquitin-interacting motif (UIM) corresponding to UIM1 of HsjIa, and another highly conserved region was noted between residues 232-241. The highly conserved regions within the Hsp40 J-domains, and those amino acids therein, are suggested to be responsible for mediating this Hsp70-Hsp40 partner interaction. The thermosensitive dnaJ cbpA Escherichia coli OD259 mutant strain producing type-I Agrobacterium tumefaciens DnaJ (AgtDnaJ) was used as a model heterologous expression system in this study. AgtDnaJ was able to replace the lack of two E coli Hsp40s in vivo, DnaJ and CbpA, whereas AgtDnaJ(H33Q) was unable to. AgtDnaJ-based chimeras containing the swapped J-domains of similar type-II Hsp40 proteins, namely Hsj1Agt and Pfj4Agt, were also able to replace these in E. coli OD259. Conserved J-domain amino acids were identified and were substituted in these chimeras. Of these mutant proteins, Hsj IAgt(L8A), Hsj1Agt(R24A), Hsj1Agt(H31Q), Pfj4Agt(L 11A) and Pfj4Agt(H34Q) were not able to replace the E. coli Hsp40s, whilst Pfj4Agt(Y8A) and Pfj4Agt(R27A) were only able to partially replace them. This shows the leucine of helix I and the histidine of the loop region are key in the in vivo function of both proteins and that the arginine of helix II is key for Hsj1a. The histidine-tagged Hsj1a protein was also successfully purified from the heterologous system. The in vitro stimulated ATPase activity of human Hsp70 by Hsj1a was found to be approximately 14 nmol Pí[subscript]/min/mg, and yet not stimulated by Pfj4, suggesting a possible species-specific interaction is occurring.
- Full Text:
- Date Issued: 2007
- Authors: McNamara, Caryn
- Date: 2007
- Subjects: Heat shock proteins , Protein folding , Proteins -- Analysis , Proteins -- Structure , Plasmodium , Malaria , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4083 , http://hdl.handle.net/10962/d1007603
- Description: Protein folding, translocation, oligomeric rearrangement and degradation are vital functions to obtain correctly folded proteins in any cell. The constitutive or stress-induced members of each of the heat shock protein (Hsp) families, namely Hsp70 and Hsp40, make up the Hsp70/Hsp40 chaperone system. The Hsp40 J-domain is important for the Hsp70-Hsp40 interaction and hence function. The type-II Hsp40 proteins, Homo sapiens DnaJ 1a (Hsj1a) and Plasmodium falciparum DnaJ 4 (Pfj4), are structurally similar suggesting possible similar roles during malarial infection. This thesis has focussed on identifying whether Hsj1a and Pfj4 are functionally similar in their interaction with potential partner Hsp70 chaperones. Analysis in silico also showed Pfj4 to have a potential chaperone domain, a region resembling a ubiquitin-interacting motif (UIM) corresponding to UIM1 of HsjIa, and another highly conserved region was noted between residues 232-241. The highly conserved regions within the Hsp40 J-domains, and those amino acids therein, are suggested to be responsible for mediating this Hsp70-Hsp40 partner interaction. The thermosensitive dnaJ cbpA Escherichia coli OD259 mutant strain producing type-I Agrobacterium tumefaciens DnaJ (AgtDnaJ) was used as a model heterologous expression system in this study. AgtDnaJ was able to replace the lack of two E coli Hsp40s in vivo, DnaJ and CbpA, whereas AgtDnaJ(H33Q) was unable to. AgtDnaJ-based chimeras containing the swapped J-domains of similar type-II Hsp40 proteins, namely Hsj1Agt and Pfj4Agt, were also able to replace these in E. coli OD259. Conserved J-domain amino acids were identified and were substituted in these chimeras. Of these mutant proteins, Hsj IAgt(L8A), Hsj1Agt(R24A), Hsj1Agt(H31Q), Pfj4Agt(L 11A) and Pfj4Agt(H34Q) were not able to replace the E. coli Hsp40s, whilst Pfj4Agt(Y8A) and Pfj4Agt(R27A) were only able to partially replace them. This shows the leucine of helix I and the histidine of the loop region are key in the in vivo function of both proteins and that the arginine of helix II is key for Hsj1a. The histidine-tagged Hsj1a protein was also successfully purified from the heterologous system. The in vitro stimulated ATPase activity of human Hsp70 by Hsj1a was found to be approximately 14 nmol Pí[subscript]/min/mg, and yet not stimulated by Pfj4, suggesting a possible species-specific interaction is occurring.
- Full Text:
- Date Issued: 2007
Characterisation of InAs-based epilayers by FTIR spectroscopy
- Authors: Baisitse, Tshepiso Revonia
- Date: 2007
- Subjects: Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10534 , http://hdl.handle.net/10948/474 , Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Description: This study focuses on the characterization of InAs and InAs1-xSbx epitaxial layers by infrared reflectance and transmittance spectroscopy and Hall measurements. Reflectance measurements were performed in order to obtain the dielectric parameters and to extract from these information about the electrical properties (mobility and carrier concentration) of this important III-V material system. The transmittance measurements were used to determine the bandgap of InAsSb. Infrared reflectivity and transmittance measurements were performed in the wavelength range 200 – 2000 cm-1 on InAs and InAsSb layers grown on three types of substrates. A classical two oscillator model that takes into account both the free carriers and the lattice, was used to analyse the reflectance data using the BMDP® computer curve fitting software. The dielectric parameters and the electrical properties (carrier concentration and mobility) were extracted from the simulations. Due to the low free carrier concentration in the epitaxial structures, the plasma resonance frequency (ωp) values obtained from the simulations of reflectance spectra measured above 200 cm-1, were in the order of 20-30 cm-1. These low values were confirmed by direct measurements of ωp in reflectance spectra obtained in the range 15-200 cm-1. The simulated carrier concentration and mobility values determined optically were compared to the values determined by Hall measurements at room temperature and previously reported values by other researchers. The simulated values obtained were in reasonable agreement with the Hall values. The simulated and measured carrier concentrations obtained for InAs layers were significantly higher than the intrinsic carrier concentration for InAs at room temperature, indicating notable concentrations of donors resulting from the growth process.
- Full Text:
- Date Issued: 2007
- Authors: Baisitse, Tshepiso Revonia
- Date: 2007
- Subjects: Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10534 , http://hdl.handle.net/10948/474 , Fourier transform infrared spectroscopy , Gallium arsenide semiconductors
- Description: This study focuses on the characterization of InAs and InAs1-xSbx epitaxial layers by infrared reflectance and transmittance spectroscopy and Hall measurements. Reflectance measurements were performed in order to obtain the dielectric parameters and to extract from these information about the electrical properties (mobility and carrier concentration) of this important III-V material system. The transmittance measurements were used to determine the bandgap of InAsSb. Infrared reflectivity and transmittance measurements were performed in the wavelength range 200 – 2000 cm-1 on InAs and InAsSb layers grown on three types of substrates. A classical two oscillator model that takes into account both the free carriers and the lattice, was used to analyse the reflectance data using the BMDP® computer curve fitting software. The dielectric parameters and the electrical properties (carrier concentration and mobility) were extracted from the simulations. Due to the low free carrier concentration in the epitaxial structures, the plasma resonance frequency (ωp) values obtained from the simulations of reflectance spectra measured above 200 cm-1, were in the order of 20-30 cm-1. These low values were confirmed by direct measurements of ωp in reflectance spectra obtained in the range 15-200 cm-1. The simulated carrier concentration and mobility values determined optically were compared to the values determined by Hall measurements at room temperature and previously reported values by other researchers. The simulated values obtained were in reasonable agreement with the Hall values. The simulated and measured carrier concentrations obtained for InAs layers were significantly higher than the intrinsic carrier concentration for InAs at room temperature, indicating notable concentrations of donors resulting from the growth process.
- Full Text:
- Date Issued: 2007
Characterization of self-assembled monolayers of iron and cobalt octaalkylthiosubstituted phthalocyanines and their use in nitrite electrocatalytic oxidation
- Matemadombo, Fungisai, Nyokong, Tebello
- Authors: Matemadombo, Fungisai , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271182 , vital:54519 , xlink:href="https://doi.org/10.1016/j.electacta.2007.05.002"
- Description: Cobalt and iron phenylthiosubstituted phthalocyanines have been deposited on Au electrode surfaces through the self-assembled monolayer (SAM) technique. The so formed layers were studied using voltammetric and impedance techniques. These SAMs blocked a number of Faradic processes and electrocatalyzed the oxidation of nitrite. The electrocatalytic parameters of the cobalt and iron phenylthiosubstituted phthalocyanines deposited on Au electrodes in nitrite solution were studied. Nitrite overpotentials which are lower than ever reported were obtained in this work for the iron phenylthiosubstituted phthalocyanines with very high stability.
- Full Text:
- Date Issued: 2007
- Authors: Matemadombo, Fungisai , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271182 , vital:54519 , xlink:href="https://doi.org/10.1016/j.electacta.2007.05.002"
- Description: Cobalt and iron phenylthiosubstituted phthalocyanines have been deposited on Au electrode surfaces through the self-assembled monolayer (SAM) technique. The so formed layers were studied using voltammetric and impedance techniques. These SAMs blocked a number of Faradic processes and electrocatalyzed the oxidation of nitrite. The electrocatalytic parameters of the cobalt and iron phenylthiosubstituted phthalocyanines deposited on Au electrodes in nitrite solution were studied. Nitrite overpotentials which are lower than ever reported were obtained in this work for the iron phenylthiosubstituted phthalocyanines with very high stability.
- Full Text:
- Date Issued: 2007
Characterization of WC-VC-Co and WC-VC-TiC-Co hardmetals
- Authors: Hashe, Nobom Gretta
- Date: 2007
- Subjects: Carbides , Hard materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10533 , http://hdl.handle.net/10948/522 , http://hdl.handle.net/10948/d1011723 , Carbides , Hard materials
- Description: This thesis contains the results of a study focused on cubic carbide and carbonitride grain growth retardation in hardmetals. Large additions of VC, or VC and TiC, or (W,V)C were made to the WC-Co hardmetal, which was then sintered in vacuum or nitrogen. The effectiveness of Ti as the grain growth inhibitor, and the influence of nitrogen sintering on grain coarsening were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractrometry (XRD) and atom probe field ion microscope (APFIM). Analysis of vacuum-sintered WC-VC-Co revealed that the cubic carbide grains have a core-rim structure. Ti was found to be a core-rim inhibitor in vacuum-sintered WCVC- TiC-Co. The average cubic carbide grain size distribution for the vacuumsintered materials was narrowed in the Ti-containing hardmetal. The nitrogen-sintered WC-VC-TiC-Co consisted of two phases of cubic carbonitride, one with high Ti-content and the other with high (W,V)-content. The surface region of the nitrogen-sintered WC-VC-TiC-Co was covered with a cubic carbonitride phase. Similar phenomena was observed in nitrogen-sintered WC-VC-Co where two types of carbonitrides were found, those with high V-content and the others with low Vcontent. A gradient zone, consisting of fine WC grains in a Co-rich binder and free from cubic carbonitride grains, was created in the surface region. The nitrogensintered materials consisted of a narrow grain size distribution. The use of (W,V)C as a starting powder affected the mechanical properties of the material with the WC-(W,V)C-Co material being the hardest of those produced in this study. Addition of (W,V)C powder to WC-Co was shown to be the most effective way to limit the cubic carbide grain size during sintering and produce a hard material. The cubic carbide grain size in the material produced this way was the smallest of all studied.
- Full Text:
- Date Issued: 2007
- Authors: Hashe, Nobom Gretta
- Date: 2007
- Subjects: Carbides , Hard materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10533 , http://hdl.handle.net/10948/522 , http://hdl.handle.net/10948/d1011723 , Carbides , Hard materials
- Description: This thesis contains the results of a study focused on cubic carbide and carbonitride grain growth retardation in hardmetals. Large additions of VC, or VC and TiC, or (W,V)C were made to the WC-Co hardmetal, which was then sintered in vacuum or nitrogen. The effectiveness of Ti as the grain growth inhibitor, and the influence of nitrogen sintering on grain coarsening were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractrometry (XRD) and atom probe field ion microscope (APFIM). Analysis of vacuum-sintered WC-VC-Co revealed that the cubic carbide grains have a core-rim structure. Ti was found to be a core-rim inhibitor in vacuum-sintered WCVC- TiC-Co. The average cubic carbide grain size distribution for the vacuumsintered materials was narrowed in the Ti-containing hardmetal. The nitrogen-sintered WC-VC-TiC-Co consisted of two phases of cubic carbonitride, one with high Ti-content and the other with high (W,V)-content. The surface region of the nitrogen-sintered WC-VC-TiC-Co was covered with a cubic carbonitride phase. Similar phenomena was observed in nitrogen-sintered WC-VC-Co where two types of carbonitrides were found, those with high V-content and the others with low Vcontent. A gradient zone, consisting of fine WC grains in a Co-rich binder and free from cubic carbonitride grains, was created in the surface region. The nitrogensintered materials consisted of a narrow grain size distribution. The use of (W,V)C as a starting powder affected the mechanical properties of the material with the WC-(W,V)C-Co material being the hardest of those produced in this study. Addition of (W,V)C powder to WC-Co was shown to be the most effective way to limit the cubic carbide grain size during sintering and produce a hard material. The cubic carbide grain size in the material produced this way was the smallest of all studied.
- Full Text:
- Date Issued: 2007
Child sex tourism in South African law
- Authors: Chetty, Kasturi
- Date: 2007
- Subjects: Child sexual abuse -- South Africa , Sex tourism -- Law and legislation -- South Africa , Sex crimes -- South Africa , Child prostitution -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10276 , http://hdl.handle.net/10948/485 , Child sexual abuse -- South Africa , Sex tourism -- Law and legislation -- South Africa , Sex crimes -- South Africa , Child prostitution -- South Africa
- Description: Child sex tourism is tourism organised with the primary purpose of facilitating a commercial sexual relationship with a child. It involves a segment of the local child sex industry that is directly connected to both an international and domestic tourist market. The increase of tourism has brought with it complications in that tourism is being used as a means for sex tourists to initiate contact with children. Aside from child sex tourists who are paedophiles, there are those who engage in the opportunistic exploitation of children while travelling on business or for other reasons. There are a number of social and economic factors leading to child sex tourism and the effect is that child victims are exposed to immediate harm, irreversible damage and even death. As South Africa's tourism industry expands into one of the country’s top earners of foreign currency, it is unfortunate to note that its child sex tourist trade is also on the increase. Reports show that sex tours are as easily organised as wine route tours in Cape Town. Commercial sexual exploitation of children is prevalent in South Africa and has become more organised in recent years. A comprehensive response to the problem is essential to ensure that South Africa does not become a “safe haven” for child sex tourists. Effective laws at home and the extraterritorial application of these laws to prosecute South African nationals for crimes committed abroad are imperative. Significant steps are being taken both nationally and internationally to target child sex tourism. South Africa has ratified several international instruments on children’s rights, trafficking in persons, child labour, and discrimination against women and young girls, all of which relate to child sex tourism. In doing so, South Africa has made an international commitment to uphold the provisions of these instruments and give effect to them. South Africa is therefore under an international obligation to create the necessary structures and apply mechanisms and resources to combat child sex tourism.
- Full Text:
- Date Issued: 2007
- Authors: Chetty, Kasturi
- Date: 2007
- Subjects: Child sexual abuse -- South Africa , Sex tourism -- Law and legislation -- South Africa , Sex crimes -- South Africa , Child prostitution -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10276 , http://hdl.handle.net/10948/485 , Child sexual abuse -- South Africa , Sex tourism -- Law and legislation -- South Africa , Sex crimes -- South Africa , Child prostitution -- South Africa
- Description: Child sex tourism is tourism organised with the primary purpose of facilitating a commercial sexual relationship with a child. It involves a segment of the local child sex industry that is directly connected to both an international and domestic tourist market. The increase of tourism has brought with it complications in that tourism is being used as a means for sex tourists to initiate contact with children. Aside from child sex tourists who are paedophiles, there are those who engage in the opportunistic exploitation of children while travelling on business or for other reasons. There are a number of social and economic factors leading to child sex tourism and the effect is that child victims are exposed to immediate harm, irreversible damage and even death. As South Africa's tourism industry expands into one of the country’s top earners of foreign currency, it is unfortunate to note that its child sex tourist trade is also on the increase. Reports show that sex tours are as easily organised as wine route tours in Cape Town. Commercial sexual exploitation of children is prevalent in South Africa and has become more organised in recent years. A comprehensive response to the problem is essential to ensure that South Africa does not become a “safe haven” for child sex tourists. Effective laws at home and the extraterritorial application of these laws to prosecute South African nationals for crimes committed abroad are imperative. Significant steps are being taken both nationally and internationally to target child sex tourism. South Africa has ratified several international instruments on children’s rights, trafficking in persons, child labour, and discrimination against women and young girls, all of which relate to child sex tourism. In doing so, South Africa has made an international commitment to uphold the provisions of these instruments and give effect to them. South Africa is therefore under an international obligation to create the necessary structures and apply mechanisms and resources to combat child sex tourism.
- Full Text:
- Date Issued: 2007
Clients' views on construction and design team competencies
- Authors: Crafford, Gerrit Jacobus
- Date: 2007
- Subjects: Construction industry -- Employees , Core competencies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9679 , http://hdl.handle.net/10948/490 , Construction industry -- Employees , Core competencies
- Description: The effectiveness of the design and construction team in meeting clients’ requirements entirely depends on the competency proficiency of the design and construction teams. This research presents a model of the important competencies required by the design and construction teams in order to provide a competent service as seen by the client. A review of related literature followed by interviews by selected practitioners yielded 29 architectural competencies, 31 civil engineering competencies, 32 construction management competencies, 31 project management competencies, and 33 quantity surveying competencies that were presented in a structured questionnaire. The questionnaire was completed by 52 developers from a census of developers and municipality managers in South Africa. Respondents were asked to rank or rate: the level of importance of each competency for a career in that specific discipline; how evident that competency is in the specific discipline in South Africa; the level of importance of the performance parameters to clients, and the extent to which the various disciplines realise client satisfaction relative to the various performance parameters. The techniques of re-scaling, principal component analysis, content analysis, ranking and quadrant analysis were applied to the data. Results showed a high degree of consistency among respondents in all disciplines, regardless of the demographic differences in the importance of the competencies. A factor solution was obtained for every discipline using principal component analysis on the important competencies of each discipline. The various factor solutions were in turn used to formulate a simplified model. The model shows that the factors are interdependent and interacting. The model indicates that primary competencies for each profession are supported by mostly secondary competencies. These factors v are in turn influenced by the inter-relationships between the practitioners, continued professional development/ research and universities, which are then in turn, influenced the governing bodies. The local and global environment then ultimately influences the governing bodies. An Importance-Evidence quadrant analysis was undertaken in order to integrate the rankings of the current importance levels and current proficiency levels for each discipline’s competencies, which helped to identify areas in which education and training is immediately needed. Respondents ranked all nine performance parameters above average which indicates that there are more than the traditional performance parameters of cost, quality, and time involved in satisfying clients. The research concluded that vital feedback from clients regarding the competencies required by the respective professionals in the design and construction team was obtained.
- Full Text:
- Date Issued: 2007
- Authors: Crafford, Gerrit Jacobus
- Date: 2007
- Subjects: Construction industry -- Employees , Core competencies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9679 , http://hdl.handle.net/10948/490 , Construction industry -- Employees , Core competencies
- Description: The effectiveness of the design and construction team in meeting clients’ requirements entirely depends on the competency proficiency of the design and construction teams. This research presents a model of the important competencies required by the design and construction teams in order to provide a competent service as seen by the client. A review of related literature followed by interviews by selected practitioners yielded 29 architectural competencies, 31 civil engineering competencies, 32 construction management competencies, 31 project management competencies, and 33 quantity surveying competencies that were presented in a structured questionnaire. The questionnaire was completed by 52 developers from a census of developers and municipality managers in South Africa. Respondents were asked to rank or rate: the level of importance of each competency for a career in that specific discipline; how evident that competency is in the specific discipline in South Africa; the level of importance of the performance parameters to clients, and the extent to which the various disciplines realise client satisfaction relative to the various performance parameters. The techniques of re-scaling, principal component analysis, content analysis, ranking and quadrant analysis were applied to the data. Results showed a high degree of consistency among respondents in all disciplines, regardless of the demographic differences in the importance of the competencies. A factor solution was obtained for every discipline using principal component analysis on the important competencies of each discipline. The various factor solutions were in turn used to formulate a simplified model. The model shows that the factors are interdependent and interacting. The model indicates that primary competencies for each profession are supported by mostly secondary competencies. These factors v are in turn influenced by the inter-relationships between the practitioners, continued professional development/ research and universities, which are then in turn, influenced the governing bodies. The local and global environment then ultimately influences the governing bodies. An Importance-Evidence quadrant analysis was undertaken in order to integrate the rankings of the current importance levels and current proficiency levels for each discipline’s competencies, which helped to identify areas in which education and training is immediately needed. Respondents ranked all nine performance parameters above average which indicates that there are more than the traditional performance parameters of cost, quality, and time involved in satisfying clients. The research concluded that vital feedback from clients regarding the competencies required by the respective professionals in the design and construction team was obtained.
- Full Text:
- Date Issued: 2007
Climate change, genetics or human choice: why were the shells of mankind’s earliest ornament larger in the Pleistocene than in the Holocene?
- Teske, Peter R, Papadopoulos, Isabelle, McQuaid, Christopher D, Newman, Brent K, Barker, Nigel P
- Authors: Teske, Peter R , Papadopoulos, Isabelle , McQuaid, Christopher D , Newman, Brent K , Barker, Nigel P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6952 , http://hdl.handle.net/10962/d1011984
- Description: The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from ~75,000 years ago (Pleistocene era) were found in a cave located on South Africa's south coast. Beads made from N. kraussianus shells have also been found in deposits in this region dating from the beginning of the Holocene era (<10,000 years ago). These younger shells were significantly smaller, a phenomenon that has been attributed to a change in human preference. We investigated two alternative hypotheses explaining the difference in shell size: a) N. kraussianus comprises at least two genetic lineages that differ in size; b) the difference in shell size is due to phenotypic plasticity and is a function of environmental conditions. To test these hypotheses, we first reconstructed the species' phylogeographic history, and second, we measured the shell sizes of extant individuals throughout South Africa. Although two genetic lineages were identified, the sharing of haplotypes between these suggests that there is no genetic basis for the size differences. Extant individuals from the cool temperate west coast had significantly larger shells than populations in the remainder of the country, suggesting that N. kraussianus grows to a larger size in colder water. The decrease in fossil shell size from Pleistocene to Holocene was likely due to increased temperatures as a result of climate change at the beginning of the present interglacial period. We hypothesise that the sizes of N. kraussianus fossil shells can therefore serve as indicators of the climatic conditions that were prevalent in a particular region at the time when they were deposited. Moreover, N. kraussianus could serve as a biomonitor to study the impacts of future climate change on coastal biota in southern Africa.
- Full Text:
- Date Issued: 2007
- Authors: Teske, Peter R , Papadopoulos, Isabelle , McQuaid, Christopher D , Newman, Brent K , Barker, Nigel P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6952 , http://hdl.handle.net/10962/d1011984
- Description: The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from ~75,000 years ago (Pleistocene era) were found in a cave located on South Africa's south coast. Beads made from N. kraussianus shells have also been found in deposits in this region dating from the beginning of the Holocene era (<10,000 years ago). These younger shells were significantly smaller, a phenomenon that has been attributed to a change in human preference. We investigated two alternative hypotheses explaining the difference in shell size: a) N. kraussianus comprises at least two genetic lineages that differ in size; b) the difference in shell size is due to phenotypic plasticity and is a function of environmental conditions. To test these hypotheses, we first reconstructed the species' phylogeographic history, and second, we measured the shell sizes of extant individuals throughout South Africa. Although two genetic lineages were identified, the sharing of haplotypes between these suggests that there is no genetic basis for the size differences. Extant individuals from the cool temperate west coast had significantly larger shells than populations in the remainder of the country, suggesting that N. kraussianus grows to a larger size in colder water. The decrease in fossil shell size from Pleistocene to Holocene was likely due to increased temperatures as a result of climate change at the beginning of the present interglacial period. We hypothesise that the sizes of N. kraussianus fossil shells can therefore serve as indicators of the climatic conditions that were prevalent in a particular region at the time when they were deposited. Moreover, N. kraussianus could serve as a biomonitor to study the impacts of future climate change on coastal biota in southern Africa.
- Full Text:
- Date Issued: 2007
Co-engaged learning : Xhosa women's narratives on traditional foods
- Authors: Jolly, Rachel
- Date: 2007
- Subjects: Xhosa (African people) -- Social life and customs -- South Africa -- Grahamstown Women, Xhosa -- South Africa -- Grahamstown Nutrition -- Study and teaching -- South Africa -- Grahamstown Ethnoscience -- Study and teaching -- South Africa -- Grahamstown AIDS (Disease) -- South Africa -- Grahamstown HIV infections -- South Africa -- Grahamstown Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1450 , http://hdl.handle.net/10962/d1003331
- Description: This interpretive case study examines Grahamstown East Xhosa women's narratives on the nutritional value of traditional foods. It reviews reflexive learning interactions apparent in the co-engaged narratives of food preparation practices. The research design incorporates methods of reflective co-engagement through which a small team of women were approached as 'co-researchers' in order to work together on shared, local knowledge capital and nutrition concerns. It draws on findings generated using a combination of semi-structured interviews, cooking demonstrations, videography, photographs and field observations as methods of data collection. Data were member-checked and reviewed in a rural context before the emerging evidence was analyzed using Bassey's (1999) analytical statements. Contextual factors influencing the study are high poverty, unemployment and HIV/AIDS prevalence where nutrition levels have been found to be low. The women making up the study have spent the majority of their lives in the peri-urban area of Grahamstown and in some cases, are more than one generation removed from rural living and its associated knowledge. The accompanying shift to modernization was found to influence the interplay between their narratives and practice. Indigenous Knowledge is often characterized by being situated in practice with the knowledge-holders often not 'knowing that they know.' This study concludes that it is not possible to assume that knowledge can always be consciously expressed, especially when that knowledge is embedded in practice. Related to this, co-engagement and diversity among the group gave rise to greater disequilibrium as well as making the knowledge more explicit and hence, available for reflection. The study suggests that through the process of co-engagement and deliberation around indigenous ways of knowing, agency and cultural identity appears to be enabled and strengthened.
- Full Text:
- Date Issued: 2007
- Authors: Jolly, Rachel
- Date: 2007
- Subjects: Xhosa (African people) -- Social life and customs -- South Africa -- Grahamstown Women, Xhosa -- South Africa -- Grahamstown Nutrition -- Study and teaching -- South Africa -- Grahamstown Ethnoscience -- Study and teaching -- South Africa -- Grahamstown AIDS (Disease) -- South Africa -- Grahamstown HIV infections -- South Africa -- Grahamstown Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1450 , http://hdl.handle.net/10962/d1003331
- Description: This interpretive case study examines Grahamstown East Xhosa women's narratives on the nutritional value of traditional foods. It reviews reflexive learning interactions apparent in the co-engaged narratives of food preparation practices. The research design incorporates methods of reflective co-engagement through which a small team of women were approached as 'co-researchers' in order to work together on shared, local knowledge capital and nutrition concerns. It draws on findings generated using a combination of semi-structured interviews, cooking demonstrations, videography, photographs and field observations as methods of data collection. Data were member-checked and reviewed in a rural context before the emerging evidence was analyzed using Bassey's (1999) analytical statements. Contextual factors influencing the study are high poverty, unemployment and HIV/AIDS prevalence where nutrition levels have been found to be low. The women making up the study have spent the majority of their lives in the peri-urban area of Grahamstown and in some cases, are more than one generation removed from rural living and its associated knowledge. The accompanying shift to modernization was found to influence the interplay between their narratives and practice. Indigenous Knowledge is often characterized by being situated in practice with the knowledge-holders often not 'knowing that they know.' This study concludes that it is not possible to assume that knowledge can always be consciously expressed, especially when that knowledge is embedded in practice. Related to this, co-engagement and diversity among the group gave rise to greater disequilibrium as well as making the knowledge more explicit and hence, available for reflection. The study suggests that through the process of co-engagement and deliberation around indigenous ways of knowing, agency and cultural identity appears to be enabled and strengthened.
- Full Text:
- Date Issued: 2007
Cobalt Phthalocyanine Molecular Electrode for the Electrochemical Investigation of the Release of Glutathione upon Copper-Catalyzed Decomposition of S-Nitrosoglutathione
- Sehlotho, Nthapo, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281201 , vital:55701 , xlink:href="https://doi.org/10.1002/elan.200603656"
- Description: Decomposition of S-nitrosoglutathione (GSNO) in phosphate buffer solution at physiological pH 7.4 in the presence of cuprous ion as a catalyst and sodium borohydride as a reducing agent is analyzed by observing the transient apparition of reduced glutathione GSH through its electrooxidation. Transient formation of GSH, upon decomposition of 1 mM GSNO in presence of 0.025 mM Cu(NO3)2 and 1 mM NaBH4 was detected by using an ordinary pyrolytic graphite electrode modified with an adsorbed monolayer of cobalt phthalocyanine at 0 V vs. SCE.
- Full Text:
- Date Issued: 2007
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281201 , vital:55701 , xlink:href="https://doi.org/10.1002/elan.200603656"
- Description: Decomposition of S-nitrosoglutathione (GSNO) in phosphate buffer solution at physiological pH 7.4 in the presence of cuprous ion as a catalyst and sodium borohydride as a reducing agent is analyzed by observing the transient apparition of reduced glutathione GSH through its electrooxidation. Transient formation of GSH, upon decomposition of 1 mM GSNO in presence of 0.025 mM Cu(NO3)2 and 1 mM NaBH4 was detected by using an ordinary pyrolytic graphite electrode modified with an adsorbed monolayer of cobalt phthalocyanine at 0 V vs. SCE.
- Full Text:
- Date Issued: 2007
Collaborative research with traditional African health practitioners of the Nelson Mandela Metropole : antimicrobial, anticancer and anti-diabetic activities of five medicinal plants
- Authors: Van Huyssteen, Mea
- Date: 2007
- Subjects: Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10148 , http://hdl.handle.net/10948/663 , Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Description: The promotion and development of indigenous knowledge pertaining to the traditional African healing system is one of the prime objectives set out by the South African government. Despite excellent research opportunities and funding, the biggest problem with ethnopharmacological research is a lack of interaction with indigenous communities, which tends to dilute the benefits this research has to offer these communities. The primary aim of this study was thus to promote the traditional African healing system through collaborative medicinal plant research with local traditional health practitioners. The research collaboration aimed to validate some biological activities of traditional remedies used by collaborating traditional health practitioners and ensured interactive sessions where scientific literature, research practices, findings and relevant legislation were discussed and debated. The joint development of a medicinal garden was a valuable tool in realising these goals. Aqueous and ethanol extracts of Bulbine frutescens, Ornithogalum longibracteatum, Ruta graveolens, Tarchonanthus camphoratus and Tulbaghia violacea were selected for antimicrobial, anticancer and anti-diabetic screening, because of their sustainable utilisation potential. The ethanol extract of T. violacea produced the best antimicrobial activity on Bacillus subtilis (100% growth inhibition) and Candida albicans (89% growth inhibition) at 250 μg/ml. The EC50 for the ethanol extract of T. violacea against HT29 colon cancer cells was 101 μg/ml. The aqueous extracts of B. frutescens and T. camphoratus (0.5 and 50 μg/ml) produced the highest overall glucose uptake activity in Chang liver and C2C12 muscle cells. T. camphoratus was unanimously chosen by participating practitioners as the plant to be investigated further. The aqueous extract of T. camphoratus increased glucose uptake in C2C12 muscle cells through increased translocation of GLUT4 to the plasma membrane and activation of the PI3-kinase and AMP-kinase pathways. It produced some alpha-glucosidase inhibitory activity at concentrations of ≥ 200 μg/ml. Apart from interactive feedback seminars at which the findings were presented to participating practitioners, all scientific literature regarding the plants was summarised, translated, compiled and given to participating practitioners in written format. An indigenous knowledge agreement has been negotiated and will formalise the collaboration in future. It is recommended that future research focuses on plants with economic development potential that can be cultivated in the medicinal garden.
- Full Text:
- Date Issued: 2007
- Authors: Van Huyssteen, Mea
- Date: 2007
- Subjects: Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10148 , http://hdl.handle.net/10948/663 , Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Description: The promotion and development of indigenous knowledge pertaining to the traditional African healing system is one of the prime objectives set out by the South African government. Despite excellent research opportunities and funding, the biggest problem with ethnopharmacological research is a lack of interaction with indigenous communities, which tends to dilute the benefits this research has to offer these communities. The primary aim of this study was thus to promote the traditional African healing system through collaborative medicinal plant research with local traditional health practitioners. The research collaboration aimed to validate some biological activities of traditional remedies used by collaborating traditional health practitioners and ensured interactive sessions where scientific literature, research practices, findings and relevant legislation were discussed and debated. The joint development of a medicinal garden was a valuable tool in realising these goals. Aqueous and ethanol extracts of Bulbine frutescens, Ornithogalum longibracteatum, Ruta graveolens, Tarchonanthus camphoratus and Tulbaghia violacea were selected for antimicrobial, anticancer and anti-diabetic screening, because of their sustainable utilisation potential. The ethanol extract of T. violacea produced the best antimicrobial activity on Bacillus subtilis (100% growth inhibition) and Candida albicans (89% growth inhibition) at 250 μg/ml. The EC50 for the ethanol extract of T. violacea against HT29 colon cancer cells was 101 μg/ml. The aqueous extracts of B. frutescens and T. camphoratus (0.5 and 50 μg/ml) produced the highest overall glucose uptake activity in Chang liver and C2C12 muscle cells. T. camphoratus was unanimously chosen by participating practitioners as the plant to be investigated further. The aqueous extract of T. camphoratus increased glucose uptake in C2C12 muscle cells through increased translocation of GLUT4 to the plasma membrane and activation of the PI3-kinase and AMP-kinase pathways. It produced some alpha-glucosidase inhibitory activity at concentrations of ≥ 200 μg/ml. Apart from interactive feedback seminars at which the findings were presented to participating practitioners, all scientific literature regarding the plants was summarised, translated, compiled and given to participating practitioners in written format. An indigenous knowledge agreement has been negotiated and will formalise the collaboration in future. It is recommended that future research focuses on plants with economic development potential that can be cultivated in the medicinal garden.
- Full Text:
- Date Issued: 2007
Collaborative versus adversarial stances in scientific discourse : implications for the role of systematic case studies in the development of evidence-based practice in psychotherapy
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6245 , http://hdl.handle.net/10962/d1007861
- Description: There is still a need for advocacy in the promotion of case study research because there has been insufficient appreciation of its role as a source of evidence relevant to the development and evaluation of practice in psychotherapy. Distorted use of terms like "gold standard", "anecdotal",and "empirical" in the discourse in which research methodology is typically presented has disempowered the practitioner's perspective and discredited the role of case-based knowledge building. The framework of evidence-based practice (EBP) recognizes the complementarity of different research methods and acknowledges the significance of casebased research. To spell out some of these complementary links, a typology of seven research methods - including both experimental group comparison designs and individual case studies - is proposed and the contribution of each to the development of EBP is set out. Finally some suggestions are made for strategies to promote the publication of high quality case studies.
- Full Text:
- Date Issued: 2007
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6245 , http://hdl.handle.net/10962/d1007861
- Description: There is still a need for advocacy in the promotion of case study research because there has been insufficient appreciation of its role as a source of evidence relevant to the development and evaluation of practice in psychotherapy. Distorted use of terms like "gold standard", "anecdotal",and "empirical" in the discourse in which research methodology is typically presented has disempowered the practitioner's perspective and discredited the role of case-based knowledge building. The framework of evidence-based practice (EBP) recognizes the complementarity of different research methods and acknowledges the significance of casebased research. To spell out some of these complementary links, a typology of seven research methods - including both experimental group comparison designs and individual case studies - is proposed and the contribution of each to the development of EBP is set out. Finally some suggestions are made for strategies to promote the publication of high quality case studies.
- Full Text:
- Date Issued: 2007
Combined and additive effects of assembly tasks and constrained body postures
- Authors: Skelton, Sarah Anne
- Date: 2007
- Subjects: Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5107 , http://hdl.handle.net/10962/d1005185 , Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Description: Despite extensive research into musculoskeletal disorders (MSDs) they continue to plague workers. Manual materials handling (MMH), in particular the concurrence of load manipulation and awkward body posture, has been identified as a key factor in the onset of MSDs. Only a few studies have looked at the interaction between manipulation tasks and working posture during assembly tasks and as a result their relationship has not been widely explored. Assessing the stresses resulting from individual task factors and body posture in isolation and adding them together may be too simplified to estimate an overall risk profile, since this does not take into account that there may be a non-linear interaction in strain responses when manipulation task and body posture interact. Therefore, the present study investigated biophysical, physiological and psychophysical responses to combined tasks, rather than individual tasks of body posture and manipulative tasks. The objective of the research was to establish the interactive effects of constrained body postures and manipulative tasks and to identify whether a cumulative or compensatory reaction occurs during this interaction. Nine conditions were assessed in a laboratory setting, which included combinations of three working postures (standing, sitting and stooping) and three assembly tasks (torque wrenching, precision and no task). Thirty-six subjects were required to complete all nine conditions, with each condition lasting ninety seconds. Muscle activity was recorded for seven muscles from the upper extremity, trunk and lower extremity regions and was complemented by physiological (heart rate, tidal volume, minute ventilation, oxygen consumption, energy expenditure and breathing frequency) and psychophysical (body discomfort) data. At the completion of all nine conditions subjects completed a retrospective psychophysical rating questionnaire pertaining to discomfort felt during the conditions. Responses obtained for the different task and posture combinations revealed compensatory reactions (additive > combined) for most of the conditions assessed for the biomechanical and physiological responses. In the majority of cases for muscle activity, no significant differences were found between the combined and the additive effects (p < 0.05), while for the physiological responses there were mostly significant differences observed. Psychophysical responses indicated that there was a significant difference overall between the additive and combined effects. The results of this study demonstrate that in order to identify risk areas, manipulation tasks and constrained working postures may be considered either in isolation and added together (additive) or as a combined task, since there were very few significant differences observed between these two effects. Further studies are required, however, to provide conclusive evidence.
- Full Text:
- Date Issued: 2007
- Authors: Skelton, Sarah Anne
- Date: 2007
- Subjects: Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5107 , http://hdl.handle.net/10962/d1005185 , Musculoskeletal system -- Diseases , Human engineering , Posture , Posture disorders , Work -- Physiological aspects , Occupational diseases , Manual work , Job stress
- Description: Despite extensive research into musculoskeletal disorders (MSDs) they continue to plague workers. Manual materials handling (MMH), in particular the concurrence of load manipulation and awkward body posture, has been identified as a key factor in the onset of MSDs. Only a few studies have looked at the interaction between manipulation tasks and working posture during assembly tasks and as a result their relationship has not been widely explored. Assessing the stresses resulting from individual task factors and body posture in isolation and adding them together may be too simplified to estimate an overall risk profile, since this does not take into account that there may be a non-linear interaction in strain responses when manipulation task and body posture interact. Therefore, the present study investigated biophysical, physiological and psychophysical responses to combined tasks, rather than individual tasks of body posture and manipulative tasks. The objective of the research was to establish the interactive effects of constrained body postures and manipulative tasks and to identify whether a cumulative or compensatory reaction occurs during this interaction. Nine conditions were assessed in a laboratory setting, which included combinations of three working postures (standing, sitting and stooping) and three assembly tasks (torque wrenching, precision and no task). Thirty-six subjects were required to complete all nine conditions, with each condition lasting ninety seconds. Muscle activity was recorded for seven muscles from the upper extremity, trunk and lower extremity regions and was complemented by physiological (heart rate, tidal volume, minute ventilation, oxygen consumption, energy expenditure and breathing frequency) and psychophysical (body discomfort) data. At the completion of all nine conditions subjects completed a retrospective psychophysical rating questionnaire pertaining to discomfort felt during the conditions. Responses obtained for the different task and posture combinations revealed compensatory reactions (additive > combined) for most of the conditions assessed for the biomechanical and physiological responses. In the majority of cases for muscle activity, no significant differences were found between the combined and the additive effects (p < 0.05), while for the physiological responses there were mostly significant differences observed. Psychophysical responses indicated that there was a significant difference overall between the additive and combined effects. The results of this study demonstrate that in order to identify risk areas, manipulation tasks and constrained working postures may be considered either in isolation and added together (additive) or as a combined task, since there were very few significant differences observed between these two effects. Further studies are required, however, to provide conclusive evidence.
- Full Text:
- Date Issued: 2007
Communication of psycho-educational assessment results: remedial teachers' reading of assessment reports
- Knoetze, Jan, Vermoter, Carey-Lee
- Authors: Knoetze, Jan , Vermoter, Carey-Lee
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6265 , http://hdl.handle.net/10962/d1008264 , http://www.sajournalofeducation.co.za/index.php/saje/article/view/47
- Description: Psychological methods of assessing intelligence have been criticised because of their limited diagnostic-remedial nature and especially their lack of potential for initiating effective and pragmatic intervention programmes. Similarly, the means through which the results of such methods are communicated in order to make them useful and constructive can be debated . In this research we aimed to establish the value of psycho-educational assessment reports in terms of the understanding and interpretation of the reports by the irrecipients, specifically remedial teachers, who participated in focus group discussions and offered their opinion on the utility of psycho-educational assessment reports. The outcomes of these focus group discussions pointed to the fact that psycho-educational assessment reports were problematic in the sense that they failed to provide useful, specific, and pragmatic information for learning support programmes to be developed from. The research revealed insights which may be of interest to psychologists writing assessment reports. Suggestions for multi-disciplinary collaboration are addressed. , The South African Journal of Education is open access and available on-line at: http://www.sajournalofeducation.co.za
- Full Text:
- Date Issued: 2007
- Authors: Knoetze, Jan , Vermoter, Carey-Lee
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6265 , http://hdl.handle.net/10962/d1008264 , http://www.sajournalofeducation.co.za/index.php/saje/article/view/47
- Description: Psychological methods of assessing intelligence have been criticised because of their limited diagnostic-remedial nature and especially their lack of potential for initiating effective and pragmatic intervention programmes. Similarly, the means through which the results of such methods are communicated in order to make them useful and constructive can be debated . In this research we aimed to establish the value of psycho-educational assessment reports in terms of the understanding and interpretation of the reports by the irrecipients, specifically remedial teachers, who participated in focus group discussions and offered their opinion on the utility of psycho-educational assessment reports. The outcomes of these focus group discussions pointed to the fact that psycho-educational assessment reports were problematic in the sense that they failed to provide useful, specific, and pragmatic information for learning support programmes to be developed from. The research revealed insights which may be of interest to psychologists writing assessment reports. Suggestions for multi-disciplinary collaboration are addressed. , The South African Journal of Education is open access and available on-line at: http://www.sajournalofeducation.co.za
- Full Text:
- Date Issued: 2007
Comparative electrooxidation of nitrite by electrodeposited Co (II), Fe (II) and Mn (III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines on gold electrodes
- Agboola, Bolade, Nyokong, Tebello
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281212 , vital:55702 , xlink:href="https://doi.org/10.1016/j.aca.2007.01.031"
- Description: This work reports on the electrooxidation of nitrite using Co(II), Fe(II) and Mn(III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines electrodeposited onto a gold electrode. Good catalytic activity (in terms of lowering overpotential) was obtained for these molecules when compared to previously reported MPc catalysts. The catalytic current was found to vary linearly with nitrite concentration in the range employed in this work (0.1–1 mM) and high sensitivities ranging from 6.9 to 9.9 μA mM−1 were observed for all the modified electrodes.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281212 , vital:55702 , xlink:href="https://doi.org/10.1016/j.aca.2007.01.031"
- Description: This work reports on the electrooxidation of nitrite using Co(II), Fe(II) and Mn(III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines electrodeposited onto a gold electrode. Good catalytic activity (in terms of lowering overpotential) was obtained for these molecules when compared to previously reported MPc catalysts. The catalytic current was found to vary linearly with nitrite concentration in the range employed in this work (0.1–1 mM) and high sensitivities ranging from 6.9 to 9.9 μA mM−1 were observed for all the modified electrodes.
- Full Text:
- Date Issued: 2007