Direct use values of secondary resources harvested from communal savannas in the Bushbuckridge lowveld, South Africa
- Shackleton, Charlie M, Shackleton, Sheona E
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182798 , vital:43875 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20000614194"
- Description: This study reports on the direct use value of secondary resources harvested by rural communities in a savanna region of South Africa. Data pertaining to the use, amount and direct use value of 11 secondary resources were presented individually, along with a final composite value. Only five resources (fuelwood, construction wood, edible fruits, edible herbs, and medicinal plants), individually accounted for more than 10% of the total value per hectare (US$ 141), and together they represented over 94% of the total value per hectare. On a per household basis, only 3 of the 11 resources contributed 10% or more to the total direct use value (US$ 386 used at home and US$ 767 traded), and together contributed greater than 71% of the total direct use value per household. Two-thirds of the value per household was traded locally with other households or regionally, rather than consumed at home. The total value per hectare compared favourably with other land uses within the region, except for capital intensive enterprises. The returns to collecting and selling secondary resources were higher than those paid for local agricultural wage labour. The extraction rates of several of the secondary resources are probably sustainable but not for the more important ones such as fuelwood, construction wood and medicinal plants.
- Full Text:
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182798 , vital:43875 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20000614194"
- Description: This study reports on the direct use value of secondary resources harvested by rural communities in a savanna region of South Africa. Data pertaining to the use, amount and direct use value of 11 secondary resources were presented individually, along with a final composite value. Only five resources (fuelwood, construction wood, edible fruits, edible herbs, and medicinal plants), individually accounted for more than 10% of the total value per hectare (US$ 141), and together they represented over 94% of the total value per hectare. On a per household basis, only 3 of the 11 resources contributed 10% or more to the total direct use value (US$ 386 used at home and US$ 767 traded), and together contributed greater than 71% of the total direct use value per household. Two-thirds of the value per household was traded locally with other households or regionally, rather than consumed at home. The total value per hectare compared favourably with other land uses within the region, except for capital intensive enterprises. The returns to collecting and selling secondary resources were higher than those paid for local agricultural wage labour. The extraction rates of several of the secondary resources are probably sustainable but not for the more important ones such as fuelwood, construction wood and medicinal plants.
- Full Text:
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:
- 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:
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:
- 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:
Electrocatalytic properties of vitamin B12 towards oxidation and reduction of nitric oxide
- Vilakazi, Sibulelo Lea, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo Lea , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293196 , vital:57064 , xlink:href="https://doi.org/10.1016/S0013-4686(00)00628-9"
- Description: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction and oxidation of nitric oxide. When VB12 is adsorbed on glassy carbon electrodes, it catalyses the reduction of nitric oxide (NO) in pH 4 and 9 buffers. In the absence of NO, cyclic voltammetry shows that VB12 is reduced by a one-step two-electron reduction from CoIII to the CoI species. Addition of NO at pH 9 to solutions of VB12 resulted in the splitting of the cyclic voltammetry peaks as a result of a consecutive one-electron reduction of the central CoIII metal in VB12 to CoII and finally to CoI. The catalytic peak for oxidation of NO on a glassy carbon electrode modified with VB12 was observed at 1.21 V versus Ag∣AgCl, at pH 9. The products of the catalytic reduction of nitric oxide include ammonia and hydroxylamine.
- Full Text:
- Authors: Vilakazi, Sibulelo Lea , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293196 , vital:57064 , xlink:href="https://doi.org/10.1016/S0013-4686(00)00628-9"
- Description: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction and oxidation of nitric oxide. When VB12 is adsorbed on glassy carbon electrodes, it catalyses the reduction of nitric oxide (NO) in pH 4 and 9 buffers. In the absence of NO, cyclic voltammetry shows that VB12 is reduced by a one-step two-electron reduction from CoIII to the CoI species. Addition of NO at pH 9 to solutions of VB12 resulted in the splitting of the cyclic voltammetry peaks as a result of a consecutive one-electron reduction of the central CoIII metal in VB12 to CoII and finally to CoI. The catalytic peak for oxidation of NO on a glassy carbon electrode modified with VB12 was observed at 1.21 V versus Ag∣AgCl, at pH 9. The products of the catalytic reduction of nitric oxide include ammonia and hydroxylamine.
- Full Text:
From virtual to physical reality with paper folding
- Authors: Bangay, Shaun D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432669 , vital:72891 , https://doi.org/10.1016/S0925-7721(99)00048-6
- Description: Objects in a virtual world can be converted into hardcopy by per-pendicular projection of each face onto a sheet of paper, cutting and gluing. Previously, use of this technique was restricted to a limited class of polyhedral objects. This paper extends this process to realis-tic virtual objects, with the traditional origami restriction of using only a single sheet of paper. A number of algorithms are explored to achieve this goal. The use of heuristics allows solutions to be found without exhaustive search of all possible layouts. Approaches to deal with pathological cases are described. The techniques have al-ready been successfully applied to a number of complex models, selected from a number of model archives on the Internet.
- Full Text:
- Authors: Bangay, Shaun D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432669 , vital:72891 , https://doi.org/10.1016/S0925-7721(99)00048-6
- Description: Objects in a virtual world can be converted into hardcopy by per-pendicular projection of each face onto a sheet of paper, cutting and gluing. Previously, use of this technique was restricted to a limited class of polyhedral objects. This paper extends this process to realis-tic virtual objects, with the traditional origami restriction of using only a single sheet of paper. A number of algorithms are explored to achieve this goal. The use of heuristics allows solutions to be found without exhaustive search of all possible layouts. Approaches to deal with pathological cases are described. The techniques have al-ready been successfully applied to a number of complex models, selected from a number of model archives on the Internet.
- Full Text:
Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae).
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446824 , vital:74563 , https://hdl.handle.net/10520/EJC17754
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446824 , vital:74563 , https://hdl.handle.net/10520/EJC17754
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
Impact of fire frequency on woody community structure and soil nutrients in the Kruger National Park
- Shackleton, Charlie M, Scholes, Robert J
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181874 , vital:43776 , xlink:href="https://doi.org/10.4102/koedoe.v43i1.210"
- Description: Although fire is recognised as an important determinant of the structure and function of South African savannas, there are few studies of long-term impacts. Controlled burning blocks of contrasting fire season and frequency have been maintained throughout the Kruger National Park for almost 50 years. This paper reports on a quantitative study of the Satara plots to determine the long-term impacts of fire frequency on woody community structure and soil nutrients. Increasing fire frequency significantly decreased woody plant basal area, biomass, density, height, and mean stem circumference. The number of stems per plant and the proportion of regenerative stems increased with increasing fire frequency. Effects on species richness of woody plants were inconsistent. There were no significant differences attributable to fire frequency for any of the soil variables except organic matter and magnesium. Organic carbon was highest in the fire exclusion treatment and lowest in soils from plots burnt triennially. Magnesium levels were greatest in the annually burnt soils and least in the triennial plots.
- Full Text:
Impact of fire frequency on woody community structure and soil nutrients in the Kruger National Park
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181874 , vital:43776 , xlink:href="https://doi.org/10.4102/koedoe.v43i1.210"
- Description: Although fire is recognised as an important determinant of the structure and function of South African savannas, there are few studies of long-term impacts. Controlled burning blocks of contrasting fire season and frequency have been maintained throughout the Kruger National Park for almost 50 years. This paper reports on a quantitative study of the Satara plots to determine the long-term impacts of fire frequency on woody community structure and soil nutrients. Increasing fire frequency significantly decreased woody plant basal area, biomass, density, height, and mean stem circumference. The number of stems per plant and the proportion of regenerative stems increased with increasing fire frequency. Effects on species richness of woody plants were inconsistent. There were no significant differences attributable to fire frequency for any of the soil variables except organic matter and magnesium. Organic carbon was highest in the fire exclusion treatment and lowest in soils from plots burnt triennially. Magnesium levels were greatest in the annually burnt soils and least in the triennial plots.
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Interaction between iron (II) tetrasulfophthalocyanine and the neurotransmitters, serotonin and dopamine
- Oni, Joshua, Nyokong, Tebello
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293223 , vital:57066 , xlink:href="https://doi.org/10.1016/S0277-5387(00)00421-6"
- Description: This work reports on the kinetics of interaction of iron(II) tetrasulfophthalocyanine, [FeTSPc]4−, with dopamine (DA) and serotonin (5-HT). The interaction results in the coordination of dopamine and serotonin to [FeTSPc]4−, followed by internal electron transfer and the formation of [(DA+)FeITSPc]4− and [(5-HT+) FeITSPc]4− complexes, respectively. The rate constants for the coordination of dopamine or serotonin to [FeTSPc]4− and the formation of the FeITSPc species were found to be kf=6.8 and 9.3 dm3 mol−1 s−1, respectively. The equilibrium constants were 2.2×103 and 1.5×103 dm3 mol−1, respectively, for the interaction of dopamine or serotonin to [FeTSPc]4−.
- Full Text:
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293223 , vital:57066 , xlink:href="https://doi.org/10.1016/S0277-5387(00)00421-6"
- Description: This work reports on the kinetics of interaction of iron(II) tetrasulfophthalocyanine, [FeTSPc]4−, with dopamine (DA) and serotonin (5-HT). The interaction results in the coordination of dopamine and serotonin to [FeTSPc]4−, followed by internal electron transfer and the formation of [(DA+)FeITSPc]4− and [(5-HT+) FeITSPc]4− complexes, respectively. The rate constants for the coordination of dopamine or serotonin to [FeTSPc]4− and the formation of the FeITSPc species were found to be kf=6.8 and 9.3 dm3 mol−1 s−1, respectively. The equilibrium constants were 2.2×103 and 1.5×103 dm3 mol−1, respectively, for the interaction of dopamine or serotonin to [FeTSPc]4−.
- Full Text:
Interaction of nitric oxide with cobalt (II) tetrasulfophthalocyanine
- Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
- Full Text:
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
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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:
- 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.
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Intertidal population structure of the edible mollusc Turbo sarmaticus (Vetigastropoda) at an unexploited and exploited sites along the coast of the Eastern Cape Province, South Africa
- Foster, Gregory G, Hodgson, Alan N
- Authors: Foster, Gregory G , Hodgson, Alan N
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447403 , vital:74622 , https://doi.org/10.1080/15627020.2000.11657088
- Description: The intertidal population structure of the large edible gastropod Turbo sarmaticus was examined at four sites along the Eastern Cape Province of South Africa. One site was free from exploitation, two were subjected to low levels of exploitationand one was heavily exploited. Within the intertidal zone at all sites there was a size-related distribution, with smalleranimals being found towards the upper mid-shore and larger animals occurring in a downshore direction. The mean shore densities (1.2–animals/m2) and biomass (4.4–9.4 g/m2) of T. sarmaticus at the sites where there was no, or minimal, exploitation of animals were not significantly different (P0.001). However, the largest animals (up to 110mmshell length) were found at the unexploited site, an offshore island. The lowest density (0.2 animals/m2) and biomass (0.4 g/m2) of T. sarmaticus was recorded at the site where the exploitation of this gastropod was intense. In addition, no animals of a legally exploitable size (>70 mm shell length) were found. It is suggested that intense over-exploitation is threatening the population at this site.
- Full Text:
- Authors: Foster, Gregory G , Hodgson, Alan N
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447403 , vital:74622 , https://doi.org/10.1080/15627020.2000.11657088
- Description: The intertidal population structure of the large edible gastropod Turbo sarmaticus was examined at four sites along the Eastern Cape Province of South Africa. One site was free from exploitation, two were subjected to low levels of exploitationand one was heavily exploited. Within the intertidal zone at all sites there was a size-related distribution, with smalleranimals being found towards the upper mid-shore and larger animals occurring in a downshore direction. The mean shore densities (1.2–animals/m2) and biomass (4.4–9.4 g/m2) of T. sarmaticus at the sites where there was no, or minimal, exploitation of animals were not significantly different (P0.001). However, the largest animals (up to 110mmshell length) were found at the unexploited site, an offshore island. The lowest density (0.2 animals/m2) and biomass (0.4 g/m2) of T. sarmaticus was recorded at the site where the exploitation of this gastropod was intense. In addition, no animals of a legally exploitable size (>70 mm shell length) were found. It is suggested that intense over-exploitation is threatening the population at this site.
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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:
- 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
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Nigrobaetis Novikova and Kluge (Ephemeroptera Baetidae): first record and new species from southern Africa, with reassignment of one northern African species.
- Lugo-Ortiz, C R, de Moor, Ferdy C
- Authors: Lugo-Ortiz, C R , de Moor, Ferdy C
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452159 , vital:75108 , https://hdl.handle.net/10520/AJA10213589_279
- Description: Nigrobaetis bethuneae sp. n. (Ephemeroptera: Baetidae) is descriptionbed from larvae collected from the Cunene (Kunene) River between Angola and Namibia. The new species represents the first record of Nigrobaetis Novikova and Kluge from southern Africa and a considerable extension of the distribution range for the genus. Nigrobaetis bethuneae is characterized by the presence of a small interantennal carina, arrangement of dorsal setae on the labrum, mandibular denticulation and setation, apicolaterally bluntly pointed labial palp segment 3, absence of hind-wing pads, presence of the first pair of gills, and general abdominal coloration. Ecological data on the new species are provided. The Algerian species Baetis rhithralis Soldan, previously considered to belong in Diphetor Waltz and McCafferty, is transferred to Nigrobaetis, and the biogeographic implications of the new assignment are discussed.
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- Authors: Lugo-Ortiz, C R , de Moor, Ferdy C
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452159 , vital:75108 , https://hdl.handle.net/10520/AJA10213589_279
- Description: Nigrobaetis bethuneae sp. n. (Ephemeroptera: Baetidae) is descriptionbed from larvae collected from the Cunene (Kunene) River between Angola and Namibia. The new species represents the first record of Nigrobaetis Novikova and Kluge from southern Africa and a considerable extension of the distribution range for the genus. Nigrobaetis bethuneae is characterized by the presence of a small interantennal carina, arrangement of dorsal setae on the labrum, mandibular denticulation and setation, apicolaterally bluntly pointed labial palp segment 3, absence of hind-wing pads, presence of the first pair of gills, and general abdominal coloration. Ecological data on the new species are provided. The Algerian species Baetis rhithralis Soldan, previously considered to belong in Diphetor Waltz and McCafferty, is transferred to Nigrobaetis, and the biogeographic implications of the new assignment are discussed.
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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/${Handle} , vital:58491 , xlink:href="https://doi.org/10.1016/S1381-1169(00)00283-1"
- Description: Photolysis of aqueous solutions of 4-chlorophenol (4-Cp) in the presence of solid neodymium diphthalocyanine ([Pc(−2)NdPc(−2)]−) and oxygen using visible and ultraviolet (UV) radiation resulted in the formation of a number of products. For photolysis in the visible region, phenol, benzoquinone, hydroquinone were observed as intermediates and 4-chlorocatechol (4-CC) as the main product; intermediates similar to those observed for visible photolysis were obtained. Langmuir–Hinshelwood kinetic model was used for treatment of photochemical data.
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Photocatalytic properties of neodymium diphthalocyanine towards the transformation of 4-chlorophenol
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${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.
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Review of policies and legislation influencing the sustainable use of South Africa's indigenous Woodlands
- Willis, Carla B, Geach, Bev S, Versfeld, Dirk, Shackleton, Charlie M
- Authors: Willis, Carla B , Geach, Bev S , Versfeld, Dirk , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182810 , vital:43881 , xlink:href="https://hdl.handle.net/10520/AJA10231765_60"
- Description: The recent completion of the South African National Land-Cover Database and the Vegetation Map of South Africa, Swaziland and Lesotho, allows for the first time a comparison to be made on a national scale between the current and potential distribution of 'natural' vegetation resources. This article compares the distribution and location of woodland-type vegetation categories defined within the National Land-Cover data and the equivalent 'Savanna-thicket Biomes' class defined within the Vegetation Mapdata. Significant differences were found, both in terms of the total areal extent, as well as the actual spatial distribution of these two data sets. These differences are a measure of the inherent mapping accuracies of each source, but rather an illustration of boundary delineation distinctions that are a result of different data sources, mapping objectives and information classes, that must be noted when comparing two essentially similar information sets.
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- Authors: Willis, Carla B , Geach, Bev S , Versfeld, Dirk , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182810 , vital:43881 , xlink:href="https://hdl.handle.net/10520/AJA10231765_60"
- Description: The recent completion of the South African National Land-Cover Database and the Vegetation Map of South Africa, Swaziland and Lesotho, allows for the first time a comparison to be made on a national scale between the current and potential distribution of 'natural' vegetation resources. This article compares the distribution and location of woodland-type vegetation categories defined within the National Land-Cover data and the equivalent 'Savanna-thicket Biomes' class defined within the Vegetation Mapdata. Significant differences were found, both in terms of the total areal extent, as well as the actual spatial distribution of these two data sets. These differences are a measure of the inherent mapping accuracies of each source, but rather an illustration of boundary delineation distinctions that are a result of different data sources, mapping objectives and information classes, that must be noted when comparing two essentially similar information sets.
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Stump size and the number of coppice shoots for selected savanna tree species
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181896 , vital:43778 , xlink:href="https://doi.org/10.1016/S0254-6299(15)31074-7"
- Description: Management of coppice dynamics of indigenous savanna trees could assist in increasing the regrowth rates or number of coppice shoots produced. This would be useful in natural resource management programmes to promote sustainable resource management. This study examined the influence of cutting height, stem size and surface area on the number of coppice shoots produced for twelve savanna species from a communal land in the Bushbuckndge lowveld. All species exhibited a strong coppicing ability following cutting. The number of shoots per stump was most frequently related to cutting height, although this was not always the most significant predictor. There were clear differences between species with respect to the number of shoots per unit surface area, the highest being for Albizia harveyii and the least Piliostlgma thonningii. The taller the potential height of a species, the fewer were the coppice shoots per stump surface area.
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- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181896 , vital:43778 , xlink:href="https://doi.org/10.1016/S0254-6299(15)31074-7"
- Description: Management of coppice dynamics of indigenous savanna trees could assist in increasing the regrowth rates or number of coppice shoots produced. This would be useful in natural resource management programmes to promote sustainable resource management. This study examined the influence of cutting height, stem size and surface area on the number of coppice shoots produced for twelve savanna species from a communal land in the Bushbuckndge lowveld. All species exhibited a strong coppicing ability following cutting. The number of shoots per stump was most frequently related to cutting height, although this was not always the most significant predictor. There were clear differences between species with respect to the number of shoots per unit surface area, the highest being for Albizia harveyii and the least Piliostlgma thonningii. The taller the potential height of a species, the fewer were the coppice shoots per stump surface area.
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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.
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- 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.
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The use of and trade in indigenous edible fruits in the Bushbuckridge savanna region, South Africa
- Shackleton, Charlie M, Dzerefos, Cathy M, Shackleton, Sheona E, Mathabela, F R
- Authors: Shackleton, Charlie M , Dzerefos, Cathy M , Shackleton, Sheona E , Mathabela, F R
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182396 , vital:43826 , xlink:href="https://doi.org/10.1080/03670244.2000.9991616"
- Description: The use, processing, cultivation and trading of indigenous edible fruits was recorded across a rainfall gradient in the Mpumalanga lowveld. Three transects, each consisting of one village in a relatively high rainfall zone, one village in a low rainfall zone, and one intermediate, were sampled by means of 20 households per village. Nearly all households made use of indigenous edible fruits to some extent, with households in the wettest region using the greatest diversity of fruits. The duration of availability of selected species was increased through drying, storing and processing the raw fruits for later consumption. Such activities were more common in the drier regions relative to the wetter villages. Just less than half the respondents maintained indigenous fruit trees within their homestead or arable fields, whereas more than 65% grew exotic commercial fruit species. Many respondents traded in edible fruits, but very few obtained a significant income in this way. Nonetheless, even casual trading provided vital supplementary income for low‐income households.
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- Authors: Shackleton, Charlie M , Dzerefos, Cathy M , Shackleton, Sheona E , Mathabela, F R
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182396 , vital:43826 , xlink:href="https://doi.org/10.1080/03670244.2000.9991616"
- Description: The use, processing, cultivation and trading of indigenous edible fruits was recorded across a rainfall gradient in the Mpumalanga lowveld. Three transects, each consisting of one village in a relatively high rainfall zone, one village in a low rainfall zone, and one intermediate, were sampled by means of 20 households per village. Nearly all households made use of indigenous edible fruits to some extent, with households in the wettest region using the greatest diversity of fruits. The duration of availability of selected species was increased through drying, storing and processing the raw fruits for later consumption. Such activities were more common in the drier regions relative to the wetter villages. Just less than half the respondents maintained indigenous fruit trees within their homestead or arable fields, whereas more than 65% grew exotic commercial fruit species. Many respondents traded in edible fruits, but very few obtained a significant income in this way. Nonetheless, even casual trading provided vital supplementary income for low‐income households.
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Woodlands in South Africa and the national forests act
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182065 , vital:43796 , xlink:href="https://doi.org/10.1080/10295925.2000.9631252"
- Description: The development of the National Forestry Action Programme (NFAP) and promulgation of the National Forests Act (NFA) have established a new vision for the care, management and distribution of benefits from South Africa's woodlands. The Department of water Affairs and Forestry is mandated with ensuring this vision is put into practice. However, historically the Department has had little to do with woodlands, and suffers from a lack of capacity and expertise, a situation which it readily acknowledges. Additionally, the legal definition of a woodland within the NFA is problematic. Within this context, this paper examines oft cited definitions of woodlands and seeks to find an appropriate one for the South African context. It then briefly reviews the major classifications of woodland types at a national scale, as the minimum basis for homogenous reporting units for which monitoring of the success of the NFAP and the NFA should be pursued. Finally, a brief description of moist/dystrophic and arid/eutrophic woodlands is presented.
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- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182065 , vital:43796 , xlink:href="https://doi.org/10.1080/10295925.2000.9631252"
- Description: The development of the National Forestry Action Programme (NFAP) and promulgation of the National Forests Act (NFA) have established a new vision for the care, management and distribution of benefits from South Africa's woodlands. The Department of water Affairs and Forestry is mandated with ensuring this vision is put into practice. However, historically the Department has had little to do with woodlands, and suffers from a lack of capacity and expertise, a situation which it readily acknowledges. Additionally, the legal definition of a woodland within the NFA is problematic. Within this context, this paper examines oft cited definitions of woodlands and seeks to find an appropriate one for the South African context. It then briefly reviews the major classifications of woodland types at a national scale, as the minimum basis for homogenous reporting units for which monitoring of the success of the NFAP and the NFA should be pursued. Finally, a brief description of moist/dystrophic and arid/eutrophic woodlands is presented.
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δ13C and δ15N biogeographic trends in rocky intertidal communities along the coast of South Africa: evidence of strong environmental signatures
- Hill, Jaclyn M, McQuaid, Christopher D
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444664 , vital:74258 , https://doi.org/10.1016/j.ecss.2008.08.005
- Description: Ecosystem dynamics driven by top-down controls have been well documented in rocky intertidal communities, while the effects of bottom-up influences are comparatively poorly understood. We hypothesized that large-scale signatures of the physical environment may be identifiable along the South African coastline as it is subject to two very different current systems (Benguela and Agulhas Currents) that profoundly influence primary production and thus both food type and availability. Through stable isotope analysis, we examined biogeographic patterns in multiple trophic levels at four sites along a 1400-km stretch of South African coastline and investigated the dietary role of macroalgal-derived organic carbon in rocky intertidal communities. The general positioning of trophic groups was comparable across all sites, with animals from the same trophic levels grouping together and with a δ15N fractionation of 1–2‰ between levels.
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- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444664 , vital:74258 , https://doi.org/10.1016/j.ecss.2008.08.005
- Description: Ecosystem dynamics driven by top-down controls have been well documented in rocky intertidal communities, while the effects of bottom-up influences are comparatively poorly understood. We hypothesized that large-scale signatures of the physical environment may be identifiable along the South African coastline as it is subject to two very different current systems (Benguela and Agulhas Currents) that profoundly influence primary production and thus both food type and availability. Through stable isotope analysis, we examined biogeographic patterns in multiple trophic levels at four sites along a 1400-km stretch of South African coastline and investigated the dietary role of macroalgal-derived organic carbon in rocky intertidal communities. The general positioning of trophic groups was comparable across all sites, with animals from the same trophic levels grouping together and with a δ15N fractionation of 1–2‰ between levels.
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