Melatonin alters the photodegradation of paracetamol
- Anoopkumar-Dukie, Shailendra, Glass, Beverley D, Walker, Roderick B, Daya, Santylal
- Authors: Anoopkumar-Dukie, Shailendra , Glass, Beverley D , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184357 , vital:44211 , xlink:href="https://doi.org/10.1211/146080800128735755"
- Description: The effects of melatonin, a known free-radical scavenger, on paracetamol in the presence of UV irradiation was studied by use of HPLC. The experiments were performed in air and nitrogen. The results show that the rate of photodegradation of melatonin is faster in air than in nitrogen whereas that of paracetamol is similar in air and nitrogen. When the two drugs were combined, melatonin retarded the degradation of paracetamol for up to 6h in the presence of nitrogen. However, in the presence of air melatonin rapidly enhances the photodegradation of paracetamol. This study shows that a combination of melatonin and paracetamol in the presence of air and UV irradiation can lead to rapid inactivation of both agents, thus raising important concerns about the possible use of melatonin as sunscreen
- Full Text:
- Date Issued: 2000
- Authors: Anoopkumar-Dukie, Shailendra , Glass, Beverley D , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184357 , vital:44211 , xlink:href="https://doi.org/10.1211/146080800128735755"
- Description: The effects of melatonin, a known free-radical scavenger, on paracetamol in the presence of UV irradiation was studied by use of HPLC. The experiments were performed in air and nitrogen. The results show that the rate of photodegradation of melatonin is faster in air than in nitrogen whereas that of paracetamol is similar in air and nitrogen. When the two drugs were combined, melatonin retarded the degradation of paracetamol for up to 6h in the presence of nitrogen. However, in the presence of air melatonin rapidly enhances the photodegradation of paracetamol. This study shows that a combination of melatonin and paracetamol in the presence of air and UV irradiation can lead to rapid inactivation of both agents, thus raising important concerns about the possible use of melatonin as sunscreen
- Full Text:
- Date Issued: 2000
Incorporating the spatial component of fisheries data into stock assessment models
- Authors: Booth, Anthony J
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124800 , vital:35698 , https://doi.10.1006/jmsc.2000.0816
- Description: Fisheries-dependent and independent data have a strong spatial component. These data are also multi-dimensional, making them difficult to visualize and analyze, prompting the use of spatial analysis to facilitate an understanding of their relationships. One aspect of fisheries data that is often ignored is the distribution and abundance of a particular resource and the fishing patterns of its harvesting fisheries. In order to improve management advice, stock assessors need to incorporate the spatial component of these data into an existing assessment framework. This paper presents a three-dimensional visualization of the age-structure and fishery dependent and independent data associated with the sparid fish Pterogymnus laniarius on the Agulhas Bank, South Africa. A spatially-referenced spawner biomass per-recruit model is developed to illustrate the applicability of incorporating spatially referenced information in providing management advice. The model provided evidence that, even on a spatial scale, fishing mortality is significantly correlated to fishing effort. Areas of high levels of spawner biomass are noted, all of which corresponded to those geographic areas with a combination of low fishing effort and high adult biomass.
- Full Text:
- Date Issued: 2000
- Authors: Booth, Anthony J
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124800 , vital:35698 , https://doi.10.1006/jmsc.2000.0816
- Description: Fisheries-dependent and independent data have a strong spatial component. These data are also multi-dimensional, making them difficult to visualize and analyze, prompting the use of spatial analysis to facilitate an understanding of their relationships. One aspect of fisheries data that is often ignored is the distribution and abundance of a particular resource and the fishing patterns of its harvesting fisheries. In order to improve management advice, stock assessors need to incorporate the spatial component of these data into an existing assessment framework. This paper presents a three-dimensional visualization of the age-structure and fishery dependent and independent data associated with the sparid fish Pterogymnus laniarius on the Agulhas Bank, South Africa. A spatially-referenced spawner biomass per-recruit model is developed to illustrate the applicability of incorporating spatially referenced information in providing management advice. The model provided evidence that, even on a spatial scale, fishing mortality is significantly correlated to fishing effort. Areas of high levels of spawner biomass are noted, all of which corresponded to those geographic areas with a combination of low fishing effort and high adult biomass.
- Full Text:
- Date Issued: 2000
Namibian workers organise
- COSATU
- Authors: COSATU
- Date: 2000
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/139645 , vital:37762
- Description: In 1987, long before Namibian independence was even on the agenda, the Congress of South African Trade Unions (COSATU) and the National Union of Namibian Workers (NUNW) decided to produce a joint book on the Namibian trade union movement. At that stage the Namibian trade unions had just begun to assert themselves. The idea of the book was to provide information useful for both Namibian and South African workers on the history of the working class struggle in Namibia. It was hoped that this would help to build a powerful working class solidarity between South African and Namibian workers. The International Labour Research and Information Group (ILRIG) - a research and educational service organisation specialising in working class struggles internationally — was commissioned by COSATU and NUNW to research, write and produce the book. Work on the book started in 1988. Between then and May 1989, two ILRIG workers visited Namibia a number of times - once with comrades from COSATU - and gathered a vast amount of information on the struggle in Namibia. Information came from workers, from trade unionists, from SWAPO, from documents and from observation. At all times in the process of writing the book, material was referred back to COSATU and NUNW for discussion and approval. The final chapter on solidarity was done at the end of August 1989, when a delegation of COSATU leaders visited Namibia to discuss setting up a permanent Working Committee with the NUNW. The book is coming at a time when Namibia is about to achieve her independence from South African colonial occupation under UN Resolution 435. The Namibian workers’ struggle for a living wage, for the right to strike, for decent houses, for jobs for all and against privatisation will not end with independence. The need for strengthening and extending trade union organisation in Namibia will not end with independence. The necessity for building solidarity between the Namibian and South African working class will not end with independence.
- Full Text:
- Date Issued: 2000
- Authors: COSATU
- Date: 2000
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/139645 , vital:37762
- Description: In 1987, long before Namibian independence was even on the agenda, the Congress of South African Trade Unions (COSATU) and the National Union of Namibian Workers (NUNW) decided to produce a joint book on the Namibian trade union movement. At that stage the Namibian trade unions had just begun to assert themselves. The idea of the book was to provide information useful for both Namibian and South African workers on the history of the working class struggle in Namibia. It was hoped that this would help to build a powerful working class solidarity between South African and Namibian workers. The International Labour Research and Information Group (ILRIG) - a research and educational service organisation specialising in working class struggles internationally — was commissioned by COSATU and NUNW to research, write and produce the book. Work on the book started in 1988. Between then and May 1989, two ILRIG workers visited Namibia a number of times - once with comrades from COSATU - and gathered a vast amount of information on the struggle in Namibia. Information came from workers, from trade unionists, from SWAPO, from documents and from observation. At all times in the process of writing the book, material was referred back to COSATU and NUNW for discussion and approval. The final chapter on solidarity was done at the end of August 1989, when a delegation of COSATU leaders visited Namibia to discuss setting up a permanent Working Committee with the NUNW. The book is coming at a time when Namibia is about to achieve her independence from South African colonial occupation under UN Resolution 435. The Namibian workers’ struggle for a living wage, for the right to strike, for decent houses, for jobs for all and against privatisation will not end with independence. The need for strengthening and extending trade union organisation in Namibia will not end with independence. The necessity for building solidarity between the Namibian and South African working class will not end with independence.
- Full Text:
- Date Issued: 2000
Cyanide-induced free radical production and lipid peroxidation in rat brain homogenate is reduced by aspirin
- Daya, Santylal, Walker, Roderick B, Anoopkumar-Dukie, Shailendra
- Authors: Daya, Santylal , Walker, Roderick B , Anoopkumar-Dukie, Shailendra
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184346 , vital:44210 , xlink:href="https://doi.org/10.1007/BF02674529"
- Description: The neuroprotective properties of aspirin were investigated using cyanide-induced neurotoxicity as model. Cyanide, a known neurotoxic agent significantly increased lipid peroxidation and superoxide anion levels in rat brain homogenate in a concentration-dependent manner (0.25–1.0 mM). When homogenate, containing 1.0 mM KCN was cotreated with aspirin (1.0 mM) there was a significant decrease in lipid peroxidation. Aspirin (0.5 mM and 1.0 mM) also significantly reduced KCN-induced superoxide anion generation. The results of the present report therefore indicate a neuroprotective role for aspirin.
- Full Text:
- Date Issued: 2000
- Authors: Daya, Santylal , Walker, Roderick B , Anoopkumar-Dukie, Shailendra
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184346 , vital:44210 , xlink:href="https://doi.org/10.1007/BF02674529"
- Description: The neuroprotective properties of aspirin were investigated using cyanide-induced neurotoxicity as model. Cyanide, a known neurotoxic agent significantly increased lipid peroxidation and superoxide anion levels in rat brain homogenate in a concentration-dependent manner (0.25–1.0 mM). When homogenate, containing 1.0 mM KCN was cotreated with aspirin (1.0 mM) there was a significant decrease in lipid peroxidation. Aspirin (0.5 mM and 1.0 mM) also significantly reduced KCN-induced superoxide anion generation. The results of the present report therefore indicate a neuroprotective role for aspirin.
- Full Text:
- Date Issued: 2000
The comparative value of wild and domestic plants in home gardens of a South African rural village
- High, Christopher, Shackleton, Charlie M
- Authors: High, Christopher , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181907 , vital:43779 , xlink:href="https://doi.org/10.1023/A:1006247614579"
- Description: Rural inhabitants make considerable use of wild resources from communal areas around their settlements, as well as from arable and residential plots. These wild resources compete with the main crops planted in arable plots and home gardens, but play a significant economic and nutritional role in rural livelihoods. This paper reports upon a conservative financial evaluation of the wild plant resources harvested from home gardens and arable plots by inhabitants of rural village in the Bushbuckridge lowveld (South Africa), and examines their importance relative to other domesticated crops. On average, each household made use of four to five species of wild plants growing on their residential plot, whereas the mean number of crop plants was 3.4. The total value of all plants was R1694 (US$ 269) per household per year, or approximately R4200 (US$ 667) per hectare of home garden per year. Wild plants represented 31% of the value of all plants grown on residential plots, relative to the 69% for domesticated crops (including fruit trees). Approximately 72% of the total value of all plant products was consumed by the household, and the remaining 28% was sold.
- Full Text:
- Date Issued: 2000
- Authors: High, Christopher , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181907 , vital:43779 , xlink:href="https://doi.org/10.1023/A:1006247614579"
- Description: Rural inhabitants make considerable use of wild resources from communal areas around their settlements, as well as from arable and residential plots. These wild resources compete with the main crops planted in arable plots and home gardens, but play a significant economic and nutritional role in rural livelihoods. This paper reports upon a conservative financial evaluation of the wild plant resources harvested from home gardens and arable plots by inhabitants of rural village in the Bushbuckridge lowveld (South Africa), and examines their importance relative to other domesticated crops. On average, each household made use of four to five species of wild plants growing on their residential plot, whereas the mean number of crop plants was 3.4. The total value of all plants was R1694 (US$ 269) per household per year, or approximately R4200 (US$ 667) per hectare of home garden per year. Wild plants represented 31% of the value of all plants grown on residential plots, relative to the 69% for domesticated crops (including fruit trees). Approximately 72% of the total value of all plant products was consumed by the household, and the remaining 28% was sold.
- Full Text:
- Date Issued: 2000
May essential provisions of a contract be determined by one of the parties alone
- Kerr, Alistair J, Glover, Graham B
- Authors: Kerr, Alistair J , Glover, Graham B
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70912 , vital:29759 , https://heinonline.org/HOL/Page?handle=hein.journals/soaf117&id=211&collection=journals&index=
- Description: When the Supreme Court of Appeal raises a question but does not answer it, what it says can be interpreted as an invitation to all those interested in the topic to discuss it. This note is a response to such an invitation in NBS Boland Bank v One Berg River Drive CC, Deeb v ABSA Bank Ltd, Friedman v Standard Bank of South Africa Ltd 1999 (4) SA 928 (SCA);[1999] 4 All SA 183, hereinafter referred to as the NBS Boland Bank case.
- Full Text: false
- Date Issued: 2000
- Authors: Kerr, Alistair J , Glover, Graham B
- Date: 2000
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70912 , vital:29759 , https://heinonline.org/HOL/Page?handle=hein.journals/soaf117&id=211&collection=journals&index=
- Description: When the Supreme Court of Appeal raises a question but does not answer it, what it says can be interpreted as an invitation to all those interested in the topic to discuss it. This note is a response to such an invitation in NBS Boland Bank v One Berg River Drive CC, Deeb v ABSA Bank Ltd, Friedman v Standard Bank of South Africa Ltd 1999 (4) SA 928 (SCA);[1999] 4 All SA 183, hereinafter referred to as the NBS Boland Bank case.
- Full Text: false
- Date Issued: 2000
HIV/AIDS Manual (project proposal)
- Labour Research Service (LRS)
- Authors: Labour Research Service (LRS)
- Date: 2000
- Language: English
- Type: instruction , text
- Identifier: http://hdl.handle.net/10962/60075 , vital:27730
- Description: HIV/AIDS Manual. This manual thus aims to contribute to ensuring greater awareness amongst trade union members of the AIDS epidemic and that the issue assumes much greater importance and becomes integral to trade union activities and work, such as, collective bargaining and shop stewards' duties.
- Full Text:
- Date Issued: 2000
- Authors: Labour Research Service (LRS)
- Date: 2000
- Language: English
- Type: instruction , text
- Identifier: http://hdl.handle.net/10962/60075 , vital:27730
- Description: HIV/AIDS Manual. This manual thus aims to contribute to ensuring greater awareness amongst trade union members of the AIDS epidemic and that the issue assumes much greater importance and becomes integral to trade union activities and work, such as, collective bargaining and shop stewards' duties.
- Full Text:
- Date Issued: 2000
An investigation into the neuroprotective properties of ibuprofen
- Lambat, Zaynab Y, Conrad, Natasha, Anoopkumar-Dukie, Shailendra, Walker, Roderick B, Daya, Santylal
- Authors: Lambat, Zaynab Y , Conrad, Natasha , Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184335 , vital:44209 , xlink:href="https://doi.org/10.1023/A:1011115006856"
- Description: There is increasing evidence suggesting a protective role for anti-inflammatory medications in neurological disorders such as Alzheimer's disease (AD). While there has not been any direct evidence for this, a number of clinical studies indicate that those patients who have had a history of nonsteroidal anti-inflammatory use, have a lower incidence of AD. Since there is currently no evidence on the mechanism by which these agents offer possible neuroprotection, we investigated the potential neuroprotective properties of the nonsteroidal anti-inflammatory drug, ibuprofen, by examining whether this agent could reduce lipid peroxidation and superoxide radical generation. Quinolinic acid and cyanide, known neurotoxins, were used to induce lipid peroxidation and superoxide anion formation respectively, in rat brain homogenate. The results show that ibuprofen significantly (p more than 0.05) reduced quinolinic acid-induced lipid peroxidation and cyanide-induced superoxide production. The results of the present report therefore suggest a possible mechanism for the neuroprotective effect of ibuprofen.
- Full Text: false
- Date Issued: 2000
- Authors: Lambat, Zaynab Y , Conrad, Natasha , Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184335 , vital:44209 , xlink:href="https://doi.org/10.1023/A:1011115006856"
- Description: There is increasing evidence suggesting a protective role for anti-inflammatory medications in neurological disorders such as Alzheimer's disease (AD). While there has not been any direct evidence for this, a number of clinical studies indicate that those patients who have had a history of nonsteroidal anti-inflammatory use, have a lower incidence of AD. Since there is currently no evidence on the mechanism by which these agents offer possible neuroprotection, we investigated the potential neuroprotective properties of the nonsteroidal anti-inflammatory drug, ibuprofen, by examining whether this agent could reduce lipid peroxidation and superoxide radical generation. Quinolinic acid and cyanide, known neurotoxins, were used to induce lipid peroxidation and superoxide anion formation respectively, in rat brain homogenate. The results show that ibuprofen significantly (p more than 0.05) reduced quinolinic acid-induced lipid peroxidation and cyanide-induced superoxide production. The results of the present report therefore suggest a possible mechanism for the neuroprotective effect of ibuprofen.
- Full Text: false
- Date Issued: 2000
The universtiy in a developing free society : challenges to autonomy and academic freedom
- Authors: Makgoba, M W
- Date: 2000
- Subjects: Academic Freedom -- South Africa Universities and colleges -- South Africa Equality Liberty Education, Higher -- Political aspects -- South Africa Education and state -- South Africa Education, Higher -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/684 , vital:19981
- Description: The real point of democratic reform, what I have been calling institutional reform, is not just to change the complexion of researchers, teachers and students, nor just to change the location of research and teaching, to be truly meaning- fill, reform has to lead to a change in the orientation of these activities. Let me take a hypothetical example, one where you succeed in adding more black and female faces to the research and leaching establishment and even to shifting the location of that establishment mainly to historically black universities - say your most advanced medical research facilities come to be located at the University of Fort Hare, with researchers mainly black and female, but the facility is still oriented to proton beam research for special types of cancer, away from the public health needs of the people - what will you have achieved? I dare say you would then have joined the ranks of independent Africa. The key issue will still remain not addressed: who should centres of research and learning serve and how? This is why I think the real challenge for all of us, whether south or north of the Limpopo, whether black or brown, yellow or white, is to begin thinking of how to root African universities in African soil.
- Full Text:
- Date Issued: 2000
- Authors: Makgoba, M W
- Date: 2000
- Subjects: Academic Freedom -- South Africa Universities and colleges -- South Africa Equality Liberty Education, Higher -- Political aspects -- South Africa Education and state -- South Africa Education, Higher -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/684 , vital:19981
- Description: The real point of democratic reform, what I have been calling institutional reform, is not just to change the complexion of researchers, teachers and students, nor just to change the location of research and teaching, to be truly meaning- fill, reform has to lead to a change in the orientation of these activities. Let me take a hypothetical example, one where you succeed in adding more black and female faces to the research and leaching establishment and even to shifting the location of that establishment mainly to historically black universities - say your most advanced medical research facilities come to be located at the University of Fort Hare, with researchers mainly black and female, but the facility is still oriented to proton beam research for special types of cancer, away from the public health needs of the people - what will you have achieved? I dare say you would then have joined the ranks of independent Africa. The key issue will still remain not addressed: who should centres of research and learning serve and how? This is why I think the real challenge for all of us, whether south or north of the Limpopo, whether black or brown, yellow or white, is to begin thinking of how to root African universities in African soil.
- Full Text:
- Date Issued: 2000
Effect of water temperature on the biogeography of South African estuarine fishes associated with the subtropical/warm temperate subtraction zone
- Maree, R C, Booth, Anthony J, Whitfield, A K
- Authors: Maree, R C , Booth, Anthony J , Whitfield, A K
- Date: 2000
- Language: English
- Type: text , Article
- Identifier: vital:7133 , http://hdl.handle.net/10962/d1011776
- Description: Estuarine biogeographical regions along the southeastern coast of South Africa were investigated in terms of fish distribution and abundance patterns, with particular emphasis on the role of water temperature in influencing these patterns. Qualitative and quantitative analyses were conducted upon the ichthyofaunal assemblages to determine whether the location of the subtropical/warm temperate boundary corresponds to that proposed by Whitfield.(n1) Analyses included the distribution ranges of species associated with estuaries according to presence/absence data, cluster analysis of gill net catches in eight estuaries along the southeastern coast and the relative proportion of tropical to temperate marine species within these eight systems. Quantitative analysis indicated that the ichthyofaunal biogeographical regions are indeed a reflection of water temperature regimes and that the subtropical/warm temperate boundary is located between the Great Kei and Mbashe estuaries. A strong negative correlation was found between the number of temperate fish species and the mean of the minimum monthly temperatures recorded in the systems studied. Qualitative analysis revealed that a barrier appears to exist in the vicinity of the Swartkops estuary, which prevents the westward migration of tropical 'vagrants'. The influence of the Agulhas Current along the east coast and its divergence from the coastline in the Algoa Bay region, as well as upwelling phenomena on the southeast and south coasts are identified as major factors that influence marine and estuarine temperature regimes and therefore the ichythyofauna of this region.
- Full Text: false
- Date Issued: 2000
- Authors: Maree, R C , Booth, Anthony J , Whitfield, A K
- Date: 2000
- Language: English
- Type: text , Article
- Identifier: vital:7133 , http://hdl.handle.net/10962/d1011776
- Description: Estuarine biogeographical regions along the southeastern coast of South Africa were investigated in terms of fish distribution and abundance patterns, with particular emphasis on the role of water temperature in influencing these patterns. Qualitative and quantitative analyses were conducted upon the ichthyofaunal assemblages to determine whether the location of the subtropical/warm temperate boundary corresponds to that proposed by Whitfield.(n1) Analyses included the distribution ranges of species associated with estuaries according to presence/absence data, cluster analysis of gill net catches in eight estuaries along the southeastern coast and the relative proportion of tropical to temperate marine species within these eight systems. Quantitative analysis indicated that the ichthyofaunal biogeographical regions are indeed a reflection of water temperature regimes and that the subtropical/warm temperate boundary is located between the Great Kei and Mbashe estuaries. A strong negative correlation was found between the number of temperate fish species and the mean of the minimum monthly temperatures recorded in the systems studied. Qualitative analysis revealed that a barrier appears to exist in the vicinity of the Swartkops estuary, which prevents the westward migration of tropical 'vagrants'. The influence of the Agulhas Current along the east coast and its divergence from the coastline in the Algoa Bay region, as well as upwelling phenomena on the southeast and south coasts are identified as major factors that influence marine and estuarine temperature regimes and therefore the ichythyofauna of this region.
- Full Text: false
- Date Issued: 2000
Electrocatalytic behavior of substituted cobalt phthalocyanines towards the oxidation of cysteine
- Maree, Suzanne, Nyokong, Tebello
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293268 , vital:57070 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293268 , vital:57070 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
Electrocatalytic behavior of substituted cobalt phthalocyanines towards the oxidation of cysteine
- Maree, Suzanne, Nyokong, Tebello
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293185 , vital:57063 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293185 , vital:57063 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
Interaction of the neurotransmitter acetylcholine with aluminium, calcium and sodium
- Matlaba, Pulane M, Daya, Santy, Nyokong, Tebello
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
Discussion document prepared for COSATU Gender Conference
- NALEDI
- Authors: NALEDI
- Date: 2000
- Subjects: NALEDI
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/151190 , vital:39037
- Description: Despite the massive contribution women make around the world, they still fall into the category of the poorest and the most oppressed. Women have borne the brunt of the social costs of the changes in the world economy such as globalisation, increased international competition, structural adjustment and the deregulation of labour legislation. Massive technological advances have done little to benefit women around the world. In fact, in many instances it has actually increased their hardships. Multinational companies search the globe for areas that offer cheap labour and poor working conditions. Globally, women make up the bulk of the army of so-called “flexible”, cheap workers sought after by employers anxious to increase their profits. It is women who are mostly to be found in sweatshops and who are least likely to be organised. In South Africa, there is already a significant trend of homeworking in the clothing sector and casualisation in the retail and other sectors. And when they are organised into unions, women struggle to be recognised as leaders in those movements.
- Full Text:
- Date Issued: 2000
- Authors: NALEDI
- Date: 2000
- Subjects: NALEDI
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/151190 , vital:39037
- Description: Despite the massive contribution women make around the world, they still fall into the category of the poorest and the most oppressed. Women have borne the brunt of the social costs of the changes in the world economy such as globalisation, increased international competition, structural adjustment and the deregulation of labour legislation. Massive technological advances have done little to benefit women around the world. In fact, in many instances it has actually increased their hardships. Multinational companies search the globe for areas that offer cheap labour and poor working conditions. Globally, women make up the bulk of the army of so-called “flexible”, cheap workers sought after by employers anxious to increase their profits. It is women who are mostly to be found in sweatshops and who are least likely to be organised. In South Africa, there is already a significant trend of homeworking in the clothing sector and casualisation in the retail and other sectors. And when they are organised into unions, women struggle to be recognised as leaders in those movements.
- Full Text:
- Date Issued: 2000
Photocatalytic properties of neodymium diphthalocyanine towards the transformation of 4-chlorophenol
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:58491 , xlink:href="https://doi.org/10.1016/S1381-1169(00)00283-1"
- Description: Photolysis of aqueous solutions of 4-chlorophenol (4-Cp) in the presence of solid neodymium diphthalocyanine ([Pc(−2)NdPc(−2)]−) and oxygen using visible and ultraviolet (UV) radiation resulted in the formation of a number of products. For photolysis in the visible region, phenol, benzoquinone, hydroquinone were observed as intermediates and 4-chlorocatechol (4-CC) as the main product; intermediates similar to those observed for visible photolysis were obtained. Langmuir–Hinshelwood kinetic model was used for treatment of photochemical data.
- Full Text:
- Date Issued: 2000
Photocatalytic properties of neodymium diphthalocyanine towards the transformation of 4-chlorophenol
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:58491 , xlink:href="https://doi.org/10.1016/S1381-1169(00)00283-1"
- Description: Photolysis of aqueous solutions of 4-chlorophenol (4-Cp) in the presence of solid neodymium diphthalocyanine ([Pc(−2)NdPc(−2)]−) and oxygen using visible and ultraviolet (UV) radiation resulted in the formation of a number of products. For photolysis in the visible region, phenol, benzoquinone, hydroquinone were observed as intermediates and 4-chlorocatechol (4-CC) as the main product; intermediates similar to those observed for visible photolysis were obtained. Langmuir–Hinshelwood kinetic model was used for treatment of photochemical data.
- Full Text:
- Date Issued: 2000
A portfolio of original compositions with a commentary
- Authors: Nkuna, Musa
- Date: 2000
- Subjects: String quartets -- Scores Song cycles -- Scores Music -- Africa -- Scores
- Language: English
- Type: text , Thesis , Masters , MMus
- Identifier: vital:2698 , http://hdl.handle.net/10962/d1018689
- Description: This portfolio consists of four diverse original compositions written in 1999 : a string quartet, a cello suite and a set of two choral pieces.
- Full Text:
- Date Issued: 2000
- Authors: Nkuna, Musa
- Date: 2000
- Subjects: String quartets -- Scores Song cycles -- Scores Music -- Africa -- Scores
- Language: English
- Type: text , Thesis , Masters , MMus
- Identifier: vital:2698 , http://hdl.handle.net/10962/d1018689
- Description: This portfolio consists of four diverse original compositions written in 1999 : a string quartet, a cello suite and a set of two choral pieces.
- Full Text:
- Date Issued: 2000
Comparative Spectroscopic and Electrochemical Properties of Bis (octakis (dodecylthio) naphthalocyaninato) europium (III) and Bis (tetra-tert-butylnaphthalocyaninato) europium (III) Complexes
- Nyokong, Tebello, Furuya, Fumio, Kobayashi, Nagao, Du, Daming, Liu, Wei, Jiang, Jianzhuang
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000