Rhodes University Research Report 2001
- Authors: Rhodes University
- Date: 2001
- Language: English
- Type: Text
- Identifier: vital:556 , http://hdl.handle.net/10962/d1011936
- Description: [From Introduction] This is the first formal research report published by Rhodes University. The reason research reports have not been published previously is that the annual Council and Senate report was largely a research report and it was unnecessary to duplicate this report. However, the required format of the University’s Annual Report has changed considerably from 2001 and no longer includes detailed information on the research outputs. I would like to add my congratulations to that of the Vice-Chancellor to all the staff and postgraduate students for their research efforts in 2001. Rhodes continues to be the leading Institution in South Africa in terms of research outputs relative to its size (determined by Government subsidy income). This is very significant and it is critical that this prominence be maintained, particularly in view of the recent restructuring of Higher Education in South Africa and the greater emphasis likely to be placed on research productivity by the revised funding formula. Research at Rhodes is actively supported by the University’s Management and a variety of internal support services including, amongst others, the Library, Information Technology, laboratory and equipment support services and the entire academic, administrative and financial infrastructure. Without this support it would be impossible to conduct research. Special thanks must go to the staff in the Research Office for all their efforts in promoting research and in particular to Moira Pogrund who complied the majority of this report.
- Full Text:
- Date Issued: 2001
- Authors: Rhodes University
- Date: 2001
- Language: English
- Type: Text
- Identifier: vital:556 , http://hdl.handle.net/10962/d1011936
- Description: [From Introduction] This is the first formal research report published by Rhodes University. The reason research reports have not been published previously is that the annual Council and Senate report was largely a research report and it was unnecessary to duplicate this report. However, the required format of the University’s Annual Report has changed considerably from 2001 and no longer includes detailed information on the research outputs. I would like to add my congratulations to that of the Vice-Chancellor to all the staff and postgraduate students for their research efforts in 2001. Rhodes continues to be the leading Institution in South Africa in terms of research outputs relative to its size (determined by Government subsidy income). This is very significant and it is critical that this prominence be maintained, particularly in view of the recent restructuring of Higher Education in South Africa and the greater emphasis likely to be placed on research productivity by the revised funding formula. Research at Rhodes is actively supported by the University’s Management and a variety of internal support services including, amongst others, the Library, Information Technology, laboratory and equipment support services and the entire academic, administrative and financial infrastructure. Without this support it would be impossible to conduct research. Special thanks must go to the staff in the Research Office for all their efforts in promoting research and in particular to Moira Pogrund who complied the majority of this report.
- Full Text:
- Date Issued: 2001
Rural resettlement scheme evaluation: a case study of the Mfengu in Tsitsikamma
- Authors: Fakudze, Churchill M
- Date: 2001
- Subjects: Land settlement , Land settlement -- South Africa -- Tsitsikamma , Land settlement -- Developing countries , Land settlement -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3309 , http://hdl.handle.net/10962/d1003097 , Land settlement , Land settlement -- South Africa -- Tsitsikamma , Land settlement -- Developing countries , Land settlement -- South Africa
- Description: In 1997 South Africa came out with a policy aimed at addressing the legacy of apartheid in respect of an unequal division of land in the country. About 3.5 million people were moved from rural and urban areas between 1960 and 1980 and deposited in the reserves or areas designed for the exclusive occupation of black people. The new land policy attempts to deal with the resultant problems. The policy advocates a three-pronged approach to land reform encompassing (i) land restitution, (ii) land redistribution and (iii) land tenure reform. A number of projects have been carried out under these three aspects. This study aims to investigate and evaluate the results of a completed land restitution case. The Mfengu of Tsitsikamma was chosen as a case study because the people have moved back and are now living on their land. The Mfengu were dispossessed of their land in 1977 by the apartheid government and their land was returned in 1994. Although this case was processed outside of the land restitution legislation (Restitution of Land Rights Act, 22 of 1994), all restitution cases where people return to their original land have to deal with the problems of resettlement. From its involvement in various involuntary resettlement projects, the World Bank concluded that the new communities of resettlers should be designed as a viable settlement system equipped with infrastructure and services and integrated in the regional socio-economic context. The host communities receiving the resettlers should be assisted to overcome possible adverse social and environmental effects from the increased population density. These concerns are valid for the South African situation, and the question is, whether this resettlement encapsulates the above. The goals of the research are twofold. To evaluate the efficiency and effectiveness of the resettlement project and its sustainability. In particular focussing on the constraints to the implementation of the land policy. Research questions include the following: How was the project carried out? Is the resettlement integrated into the socio-economic and development planning of the area? How viable and sustainable is the new settlement? What are the major problems and challenges facing this area and how can they be overcome?
- Full Text:
- Date Issued: 2001
- Authors: Fakudze, Churchill M
- Date: 2001
- Subjects: Land settlement , Land settlement -- South Africa -- Tsitsikamma , Land settlement -- Developing countries , Land settlement -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3309 , http://hdl.handle.net/10962/d1003097 , Land settlement , Land settlement -- South Africa -- Tsitsikamma , Land settlement -- Developing countries , Land settlement -- South Africa
- Description: In 1997 South Africa came out with a policy aimed at addressing the legacy of apartheid in respect of an unequal division of land in the country. About 3.5 million people were moved from rural and urban areas between 1960 and 1980 and deposited in the reserves or areas designed for the exclusive occupation of black people. The new land policy attempts to deal with the resultant problems. The policy advocates a three-pronged approach to land reform encompassing (i) land restitution, (ii) land redistribution and (iii) land tenure reform. A number of projects have been carried out under these three aspects. This study aims to investigate and evaluate the results of a completed land restitution case. The Mfengu of Tsitsikamma was chosen as a case study because the people have moved back and are now living on their land. The Mfengu were dispossessed of their land in 1977 by the apartheid government and their land was returned in 1994. Although this case was processed outside of the land restitution legislation (Restitution of Land Rights Act, 22 of 1994), all restitution cases where people return to their original land have to deal with the problems of resettlement. From its involvement in various involuntary resettlement projects, the World Bank concluded that the new communities of resettlers should be designed as a viable settlement system equipped with infrastructure and services and integrated in the regional socio-economic context. The host communities receiving the resettlers should be assisted to overcome possible adverse social and environmental effects from the increased population density. These concerns are valid for the South African situation, and the question is, whether this resettlement encapsulates the above. The goals of the research are twofold. To evaluate the efficiency and effectiveness of the resettlement project and its sustainability. In particular focussing on the constraints to the implementation of the land policy. Research questions include the following: How was the project carried out? Is the resettlement integrated into the socio-economic and development planning of the area? How viable and sustainable is the new settlement? What are the major problems and challenges facing this area and how can they be overcome?
- Full Text:
- Date Issued: 2001
SADTU draft input on WHITE PAPER No. 5 on early childhood development
- SADTU
- Authors: SADTU
- Date: 2001
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/176156 , vital:42665
- Description: SADTU welcomes the release of White Paper No. 5 on Early Childhood Development. We thank the Ministry and Department of Education for affording us this opportunity to make an input. We are however concerned that the process during its development excluded stakeholder participation.
- Full Text:
- Date Issued: 2001
- Authors: SADTU
- Date: 2001
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/176156 , vital:42665
- Description: SADTU welcomes the release of White Paper No. 5 on Early Childhood Development. We thank the Ministry and Department of Education for affording us this opportunity to make an input. We are however concerned that the process during its development excluded stakeholder participation.
- Full Text:
- Date Issued: 2001
Sapphic experience: lesbian gender identity development and diversity
- Authors: Crowley, Michelle Laureen
- Date: 2001
- Subjects: Lesbian couples Gender identity Sexual orientation Heterosexual women Lesbian feminists
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2956 , http://hdl.handle.net/10962/d1002465
- Description: This dissertation explores lesbian experience, or the psychological meaning of being lesbian from the point of view of women who call themselves lesbian. The researcher suspended the binary paradigm of sex and gender, and argued that lesbians' identity development must be understood against the background of how patriarchy understands the category 'woman' through history. Towards this purpose the pOSition of women in the West, as well as contemporary images and literature about lesbians, was reviewed. On the basis of this review questions about lesbian gender construction, lesbian identity development and lesbian individuation were identified. In order to access the psychological meaning of being lesbian, or lesbian experience from the inside out, the dream-series of three lesbians constituted an empirical basis for further exploration. These dream-series were amplified with intensive face-to-face interviews, transcribed, and subjected to a hermeneutic-phenomenological inductive method. Common inter-case concerns were identified and synthesized. In dialogue with the literature reviewed, twenty-two statements of meaning about being lesbian were distilled. These revealed two possible constructions of gender for primary lesbians. In addition, primary lesbians involved in the research demonstrated remarkable flexibility with respect to their gender orientations and gender identifications, were in the process of integrating with and differentiating from different aspects of their masculine and feminine potentials, and developed and negotiated their gender identities in relationship to both their lovers and friends. The explication also revealed that participants identified with archetypal aspects of the father that their fathers' did not express, and desired archetypal aspects of the mother that their mother's did not express. Finally, in so much as the method distinguished ~ sex, sexual identity and sexual orientation from gender, gender identity, gender identification and gender orientation, it may prove useful for exploring gender in heterosexual relating.
- Full Text:
- Date Issued: 2001
- Authors: Crowley, Michelle Laureen
- Date: 2001
- Subjects: Lesbian couples Gender identity Sexual orientation Heterosexual women Lesbian feminists
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2956 , http://hdl.handle.net/10962/d1002465
- Description: This dissertation explores lesbian experience, or the psychological meaning of being lesbian from the point of view of women who call themselves lesbian. The researcher suspended the binary paradigm of sex and gender, and argued that lesbians' identity development must be understood against the background of how patriarchy understands the category 'woman' through history. Towards this purpose the pOSition of women in the West, as well as contemporary images and literature about lesbians, was reviewed. On the basis of this review questions about lesbian gender construction, lesbian identity development and lesbian individuation were identified. In order to access the psychological meaning of being lesbian, or lesbian experience from the inside out, the dream-series of three lesbians constituted an empirical basis for further exploration. These dream-series were amplified with intensive face-to-face interviews, transcribed, and subjected to a hermeneutic-phenomenological inductive method. Common inter-case concerns were identified and synthesized. In dialogue with the literature reviewed, twenty-two statements of meaning about being lesbian were distilled. These revealed two possible constructions of gender for primary lesbians. In addition, primary lesbians involved in the research demonstrated remarkable flexibility with respect to their gender orientations and gender identifications, were in the process of integrating with and differentiating from different aspects of their masculine and feminine potentials, and developed and negotiated their gender identities in relationship to both their lovers and friends. The explication also revealed that participants identified with archetypal aspects of the father that their fathers' did not express, and desired archetypal aspects of the mother that their mother's did not express. Finally, in so much as the method distinguished ~ sex, sexual identity and sexual orientation from gender, gender identity, gender identification and gender orientation, it may prove useful for exploring gender in heterosexual relating.
- Full Text:
- Date Issued: 2001
Scales of mussel bed complexity: structure, associated biota and recruitment
- Lawrie, S M, McQuaid, Christopher D
- Authors: Lawrie, S M , McQuaid, Christopher D
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6956 , http://hdl.handle.net/10962/d1011996
- Description: Hierarchically scaled surveys were carried out on beds of the brown mussel Perna perna (Linnaeus) on the South coast of South Africa. The object was to assess spatial and temporal variations in the complexity of mussel beds and to investigate relationships between mussel bed complexity and mussel recruitment. Complexity was divided into three components: physical complexity; demographic complexity; associated biota. A series of variables within each component were recorded at two different scales (10 and 50 cm) within nested quadrats on three separate occasions. The nested ANOVA design explicitly incorporated spatial scale as levels of the ANOVA. These scales were: shores (areas 1 km in length separated by 25 km); transects (areas 20 m in length separated by 100s of meters); 50×50-cm quadrats separated by meters and 10×10-cm quadrats separated by cm) This approach was intended to generate hypotheses concerning direct associations between recruitment and complexity versus co-variation due external processes. Three main questions were addressed: (1) At what scale does each variable of complexity exhibit greatest significant variation? (2) At these scales is there similar ranking of variables of complexity and recruitment? (3) Within this/these scales, is there any significant relationship between the variables measured and mussel recruitment? On two occasions (Nov. 97 and Mar. 98) the majority of variables showed greatest significant variation at the transect-scale. On a third occasion (Oct. 97) most variables showed greatest significant variation at the quadrat-scale and the site-scale. On all occasions a markedly high percentage of the variation encountered also occurred at the smallest scale of the study, i.e., the residual scale of the ANOVA analyses. Some similarity in the ranking of variables occurred at the transect scale. Within the transect-scale, there was little indication of any relationship between variables of complexity and recruitment. Relationships were inconsistent either among transects or among sampling occasions. Overall, the results suggest that a high degree of variation in mussel bed complexity consistently occurs at very small scales. High components of variance generally also occur at one or more larger scales; however, these scales vary with season. Mussel recruitment does not appear to be directly affected by complexity of mussel beds. Instead it appears external factors may influence both complexity and recruitment independently. In addition recruitment may influence complexity rather than vice versa.
- Full Text:
- Date Issued: 2001
- Authors: Lawrie, S M , McQuaid, Christopher D
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6956 , http://hdl.handle.net/10962/d1011996
- Description: Hierarchically scaled surveys were carried out on beds of the brown mussel Perna perna (Linnaeus) on the South coast of South Africa. The object was to assess spatial and temporal variations in the complexity of mussel beds and to investigate relationships between mussel bed complexity and mussel recruitment. Complexity was divided into three components: physical complexity; demographic complexity; associated biota. A series of variables within each component were recorded at two different scales (10 and 50 cm) within nested quadrats on three separate occasions. The nested ANOVA design explicitly incorporated spatial scale as levels of the ANOVA. These scales were: shores (areas 1 km in length separated by 25 km); transects (areas 20 m in length separated by 100s of meters); 50×50-cm quadrats separated by meters and 10×10-cm quadrats separated by cm) This approach was intended to generate hypotheses concerning direct associations between recruitment and complexity versus co-variation due external processes. Three main questions were addressed: (1) At what scale does each variable of complexity exhibit greatest significant variation? (2) At these scales is there similar ranking of variables of complexity and recruitment? (3) Within this/these scales, is there any significant relationship between the variables measured and mussel recruitment? On two occasions (Nov. 97 and Mar. 98) the majority of variables showed greatest significant variation at the transect-scale. On a third occasion (Oct. 97) most variables showed greatest significant variation at the quadrat-scale and the site-scale. On all occasions a markedly high percentage of the variation encountered also occurred at the smallest scale of the study, i.e., the residual scale of the ANOVA analyses. Some similarity in the ranking of variables occurred at the transect scale. Within the transect-scale, there was little indication of any relationship between variables of complexity and recruitment. Relationships were inconsistent either among transects or among sampling occasions. Overall, the results suggest that a high degree of variation in mussel bed complexity consistently occurs at very small scales. High components of variance generally also occur at one or more larger scales; however, these scales vary with season. Mussel recruitment does not appear to be directly affected by complexity of mussel beds. Instead it appears external factors may influence both complexity and recruitment independently. In addition recruitment may influence complexity rather than vice versa.
- Full Text:
- Date Issued: 2001
Sedimentology of the Karoo Supergroup in the Tuli Basin (Limpompo River area, South Africa)
- Authors: Bordy, Emese M
- Date: 2001
- Subjects: River sediments -- South Africa Sedimentology Limpopo river Sedimentology -- Limpopo river Limpopo river (South africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4999 , http://hdl.handle.net/10962/d1005612
- Description: The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) consist of various terrigenous clastic and chemical deposits (parabreccias, conglo-breccias, conglomerates, sandstones, fine-grained sediments, calcretes and silc~etes). Four stratigraphic units were identified: the Basal, Middle and· Upper Units, and the CI~rens Formation. The palaeo-environmental reconstructions of the four stratigraphic units are based on evidence provided by primary sedimentary structures, palaeo-flow measurements, clast size/shape analysis, petrographic studies, palaeontological findings, borehole data and stratigraphic relations. The facies associations of the Basal Unit are interpreted as colluvial fan and low sinuosity, braid~d river channel with coal-bearing overbank and thaw-lake deposits. The interpreted depositional environment implies a cold climate, non-glacial subarctic fluvio-Iacustrine system. The current indicators of the palaeo-river system suggest flow direction from ENE to WSW. The lithologies of the Basal Unit are very similar to the deposits of the fluvial interval in the Vryheid Formation (Ecca Group) of the main Karoo Basin. There is no indubitable evidence for glacial activity (e.g. striated pavements or clasts, varvites, etc.), therefore the presence of unequivocal Dwyka Group correlatives in the Tuli Basin remains uncertain. The sedimentary structures and palaeo-current analysis indicate that the beds of the Middle Unit were deposited by an ancient river system flowing in a north-northwesterly direction. A lack of good quality exposures did not allow the reconstruction of the fluvial style, but the available data indicate a high-energy, perhaps braided fluvial system. The lack of bio- and chronostr~~igraphic control hampers precise correlation and enables only the lithocorrelation of the Middle Unit with other braided river systems either in the Beaufort Group or in the Molteno Formation of the main Karoo Basin. The depositional environment of the Upper Unit is interpreted as a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the unit, the climate was semi-arid with sparse precipitation resulting -iFlhighmagnitude, low-frequency devastating flash floods. The sediments were built out from a distant northwesterly source to the southeast. The unambiguous correspondence between the Upper Unit and the Elliot Formation (main Karoo Basin) is provided by lithological similarities and prosauropod dinosaurs remains. The palaeo-geographic picture of the Clarens Fonnation indicates a westerly windsdominated erg environment with migrating transverse dune types. The ephemeral stream deposits, fossil wood and trace fossils are only present in the lower part of the Formation, indicating that the wet-desert conditions were progressively replaced by dry-desert conditions. Based on lithological and palaeontological evidence, the Formation correlates with the Clarens Formation in the main Karoo Basin. At this stage, it remains difficult to establish the exact cause of the regional palaeo-slope changes during the deposition of the Karoo Supergroup in the Tuli Basin. It is probable that foreland system tectonics, which affected the lower part of the Supergroup (Basal Unit and Middle Unit?), were replaced by incipient continental extension and rift related tectonic movements in the Middle and Upper Units, and Clarens Formation.
- Full Text:
- Date Issued: 2001
- Authors: Bordy, Emese M
- Date: 2001
- Subjects: River sediments -- South Africa Sedimentology Limpopo river Sedimentology -- Limpopo river Limpopo river (South africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4999 , http://hdl.handle.net/10962/d1005612
- Description: The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) consist of various terrigenous clastic and chemical deposits (parabreccias, conglo-breccias, conglomerates, sandstones, fine-grained sediments, calcretes and silc~etes). Four stratigraphic units were identified: the Basal, Middle and· Upper Units, and the CI~rens Formation. The palaeo-environmental reconstructions of the four stratigraphic units are based on evidence provided by primary sedimentary structures, palaeo-flow measurements, clast size/shape analysis, petrographic studies, palaeontological findings, borehole data and stratigraphic relations. The facies associations of the Basal Unit are interpreted as colluvial fan and low sinuosity, braid~d river channel with coal-bearing overbank and thaw-lake deposits. The interpreted depositional environment implies a cold climate, non-glacial subarctic fluvio-Iacustrine system. The current indicators of the palaeo-river system suggest flow direction from ENE to WSW. The lithologies of the Basal Unit are very similar to the deposits of the fluvial interval in the Vryheid Formation (Ecca Group) of the main Karoo Basin. There is no indubitable evidence for glacial activity (e.g. striated pavements or clasts, varvites, etc.), therefore the presence of unequivocal Dwyka Group correlatives in the Tuli Basin remains uncertain. The sedimentary structures and palaeo-current analysis indicate that the beds of the Middle Unit were deposited by an ancient river system flowing in a north-northwesterly direction. A lack of good quality exposures did not allow the reconstruction of the fluvial style, but the available data indicate a high-energy, perhaps braided fluvial system. The lack of bio- and chronostr~~igraphic control hampers precise correlation and enables only the lithocorrelation of the Middle Unit with other braided river systems either in the Beaufort Group or in the Molteno Formation of the main Karoo Basin. The depositional environment of the Upper Unit is interpreted as a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the unit, the climate was semi-arid with sparse precipitation resulting -iFlhighmagnitude, low-frequency devastating flash floods. The sediments were built out from a distant northwesterly source to the southeast. The unambiguous correspondence between the Upper Unit and the Elliot Formation (main Karoo Basin) is provided by lithological similarities and prosauropod dinosaurs remains. The palaeo-geographic picture of the Clarens Fonnation indicates a westerly windsdominated erg environment with migrating transverse dune types. The ephemeral stream deposits, fossil wood and trace fossils are only present in the lower part of the Formation, indicating that the wet-desert conditions were progressively replaced by dry-desert conditions. Based on lithological and palaeontological evidence, the Formation correlates with the Clarens Formation in the main Karoo Basin. At this stage, it remains difficult to establish the exact cause of the regional palaeo-slope changes during the deposition of the Karoo Supergroup in the Tuli Basin. It is probable that foreland system tectonics, which affected the lower part of the Supergroup (Basal Unit and Middle Unit?), were replaced by incipient continental extension and rift related tectonic movements in the Middle and Upper Units, and Clarens Formation.
- Full Text:
- Date Issued: 2001
Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa
- Bordy, Emese M, Catuneanu, O
- Authors: Bordy, Emese M , Catuneanu, O
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6731 , http://hdl.handle.net/10962/d1007540
- Description: The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) may be grouped in four stratigraphic units: the basal, middle and upper units, and the Clarens Formation. This paper presents the findings of the sedimentological investigation of the fluvial terrigenous clastic and chemical deposits of the upper unit. Evidence provided by primary sedimentary structures, palaeontological record, borehole data, palaeo-flow measurements and stratigraphic relations resulted in the palaeo-environmental reconstruction of the upper unit. The dominant facies assemblages are represented by sandstones and finer-grained sediments, which both can be interbedded with subordinate intraformational coarser facies. The facies assemblages of the upper unit are interpreted as deposits of a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the upper unit, the climate was semi-arid with sparse precipitation resulting in high-magnitude, low-frequency devastating flash floods. The current indicators of the palaeo-drainage system suggest flow direction from northwest to southeast, in a dominantly extensional tectonic setting. Based on sedimentologic and biostratigraphic evidence, the upper unit of the Tuli Basin correlates to the Elliot Formation in the main Karoo Basin to the south.
- Full Text:
- Date Issued: 2001
- Authors: Bordy, Emese M , Catuneanu, O
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6731 , http://hdl.handle.net/10962/d1007540
- Description: The sedimentary rocks of the Karoo Supergroup in the Tuli Basin (South Africa) may be grouped in four stratigraphic units: the basal, middle and upper units, and the Clarens Formation. This paper presents the findings of the sedimentological investigation of the fluvial terrigenous clastic and chemical deposits of the upper unit. Evidence provided by primary sedimentary structures, palaeontological record, borehole data, palaeo-flow measurements and stratigraphic relations resulted in the palaeo-environmental reconstruction of the upper unit. The dominant facies assemblages are represented by sandstones and finer-grained sediments, which both can be interbedded with subordinate intraformational coarser facies. The facies assemblages of the upper unit are interpreted as deposits of a low-sinuosity, ephemeral stream system with calcretes and silcretes in the dinosaur-inhabited overbank area. During the deposition of the upper unit, the climate was semi-arid with sparse precipitation resulting in high-magnitude, low-frequency devastating flash floods. The current indicators of the palaeo-drainage system suggest flow direction from northwest to southeast, in a dominantly extensional tectonic setting. Based on sedimentologic and biostratigraphic evidence, the upper unit of the Tuli Basin correlates to the Elliot Formation in the main Karoo Basin to the south.
- Full Text:
- Date Issued: 2001
Silicon octaphenoxyphthalocyanines
- Maree, M David, Kuznetsova, Nina, Nyokong, Tebello
- Authors: Maree, M David , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291591 , vital:56890 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00409-9"
- Description: Photochemical properties of series of axially substituted silicon octaphenoxyphthalocyanines with aryloxy, siloxy, aminoalkoxy, esters of carboxylic acids and sulphonic acid esters residues as axial ligands were studied in dimethylsulfoxide (DMSO) solution. It was found, that under Q-band excitation axial ligands in compounds studied have the propensity to be changed by hydroxyl groups with quantum yields in the range 10−5 to 10−2 depending on the nature of the axial ligand. Axial substituent phototransformation was followed by slow photobleaching of dihydroxysilicon octaphenoxyphthalocyanine (photoproduct) in self-sensitized singlet oxygen mediated oxidation of the macrocycle. Singlet oxygen quantum yields were found to be in the range 0.15–0.20 for majority of the phthalocyanines (Pc) studied.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291591 , vital:56890 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00409-9"
- Description: Photochemical properties of series of axially substituted silicon octaphenoxyphthalocyanines with aryloxy, siloxy, aminoalkoxy, esters of carboxylic acids and sulphonic acid esters residues as axial ligands were studied in dimethylsulfoxide (DMSO) solution. It was found, that under Q-band excitation axial ligands in compounds studied have the propensity to be changed by hydroxyl groups with quantum yields in the range 10−5 to 10−2 depending on the nature of the axial ligand. Axial substituent phototransformation was followed by slow photobleaching of dihydroxysilicon octaphenoxyphthalocyanine (photoproduct) in self-sensitized singlet oxygen mediated oxidation of the macrocycle. Singlet oxygen quantum yields were found to be in the range 0.15–0.20 for majority of the phthalocyanines (Pc) studied.
- Full Text:
- Date Issued: 2001
Simultaneous voltammetric determination of dopamine and serotonin on carbon paste electrodes modified with iron (II) phthalocyanine complexes
- Oni, Joshua, Nyokong, Tebello
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291603 , vital:56891 , xlink:href="https://doi.org/10.1016/S0003-2670(01)00822-4"
- Description: Carbon paste electrodes (CPE) containing iron(II) phthalocyanine (FePc) and iron(II) tetrasulfophthalocyanine ([FeTSPc]4−) were used for the detection of dopamine (DA) and serotonin (5-HT). Both complexes showed catalytic activity towards the detection of DA and 5-HT. The catalytic activities of [FeTSPc]4− and FePc are compared with those of [CoTSPc]4−, [NiTSPc] 4−, CoPc and NiPc complexes and with those of metal(II) tetraaminophthalocyanines (MTAPc, where M=Ni, Co or Fe) complexes. A significant improvement in the reversibility of the DA oxidation couple was observed on [FeTSPc]4− and FePc modified CPE. [FeTSPc]4− and other [MTSPc]4− modified electrodes inhibited the detection of ascorbic acid (AA), a major interferent in the detection of DA. Simultaneous detection of DA and 5-HT on [FeTSPc]4− modified CPE, in the presence of AA, showed that AA does not interfere with the determination of both species. Also no interference between DA and 5-HT was observed.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291603 , vital:56891 , xlink:href="https://doi.org/10.1016/S0003-2670(01)00822-4"
- Description: Carbon paste electrodes (CPE) containing iron(II) phthalocyanine (FePc) and iron(II) tetrasulfophthalocyanine ([FeTSPc]4−) were used for the detection of dopamine (DA) and serotonin (5-HT). Both complexes showed catalytic activity towards the detection of DA and 5-HT. The catalytic activities of [FeTSPc]4− and FePc are compared with those of [CoTSPc]4−, [NiTSPc] 4−, CoPc and NiPc complexes and with those of metal(II) tetraaminophthalocyanines (MTAPc, where M=Ni, Co or Fe) complexes. A significant improvement in the reversibility of the DA oxidation couple was observed on [FeTSPc]4− and FePc modified CPE. [FeTSPc]4− and other [MTSPc]4− modified electrodes inhibited the detection of ascorbic acid (AA), a major interferent in the detection of DA. Simultaneous detection of DA and 5-HT on [FeTSPc]4− modified CPE, in the presence of AA, showed that AA does not interfere with the determination of both species. Also no interference between DA and 5-HT was observed.
- Full Text:
- Date Issued: 2001
Singing in the streets
- Authors: Thomas, Cornelius
- Date: 2001
- Subjects: Musical groups Rock groups
- Type: article
- Identifier: http://hdl.handle.net/10962/32704 , vital:24072 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , MS 20 017
- Description: Photocopied article from the newspaper The Daily Dispatch about the Belltones musical group
- Full Text:
- Date Issued: 2001
- Authors: Thomas, Cornelius
- Date: 2001
- Subjects: Musical groups Rock groups
- Type: article
- Identifier: http://hdl.handle.net/10962/32704 , vital:24072 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , MS 20 017
- Description: Photocopied article from the newspaper The Daily Dispatch about the Belltones musical group
- Full Text:
- Date Issued: 2001
Social parasitism by honeybee workers (Apis mellifera capensis Escholtz): host finding and resistance of hybrid host colonies
- Neumann, Peter, Radloff, Sarah E, Moritz, Robin F A, Hepburn, H Randall, Reece, Sacha L
- Authors: Neumann, Peter , Radloff, Sarah E , Moritz, Robin F A , Hepburn, H Randall , Reece, Sacha L
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6907 , http://hdl.handle.net/10962/d1011860
- Description: We studied possible host finding and resistance mechanisms of host colonies in the context of social parasitism by Cape honeybee (Apis mellifera capensis) workers. Workers often join neighboring colonies by drifting, but long-range drifting (dispersal) to colonies far away from the maternal nests also rarely occurs. We tested the impact of queenstate and taxon of mother and host colonies on drifting and dispersing of workers and on the hosting of these workers in A. m. capensis, A. m. scutellata, and their natural hybrids. Workers were paint-marked according to colony and reintroduced into their queenright or queenless mother colonies. After 10 days, 579 out of 12,034 labeled workers were recaptured in foreign colonies. We found that drifting and dispersing represent different behaviors, which were differently affected by taxon and queenstate of both mother and host colonies. Hybrid workers drifted more often than A. m. capensis and A. m. scutellata. However, A. m. capensis workers dispersed more often than A. m. scutellata and the hybrids combined, and A. m. scutellata workers also dispersed more frequently than the hybrids. Dispersers from queenright A. m. capensis colonies were more often found in queenless host colonies and vice versa, indicating active host searching and/or a queenstate-discriminating guarding mechanism. Our data show that A. m. capensis workers disperse significantly more often than other races of A. mellifera, suggesting that dispersing represents a host finding mechanism. The lack of dispersal in hybrids and different hosting mechanisms of foreign workers by hybrid colonies may also be responsible for the stability of the natural hybrid zone between A. m. capensis and A. m. scutellata.
- Full Text:
- Date Issued: 2001
- Authors: Neumann, Peter , Radloff, Sarah E , Moritz, Robin F A , Hepburn, H Randall , Reece, Sacha L
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6907 , http://hdl.handle.net/10962/d1011860
- Description: We studied possible host finding and resistance mechanisms of host colonies in the context of social parasitism by Cape honeybee (Apis mellifera capensis) workers. Workers often join neighboring colonies by drifting, but long-range drifting (dispersal) to colonies far away from the maternal nests also rarely occurs. We tested the impact of queenstate and taxon of mother and host colonies on drifting and dispersing of workers and on the hosting of these workers in A. m. capensis, A. m. scutellata, and their natural hybrids. Workers were paint-marked according to colony and reintroduced into their queenright or queenless mother colonies. After 10 days, 579 out of 12,034 labeled workers were recaptured in foreign colonies. We found that drifting and dispersing represent different behaviors, which were differently affected by taxon and queenstate of both mother and host colonies. Hybrid workers drifted more often than A. m. capensis and A. m. scutellata. However, A. m. capensis workers dispersed more often than A. m. scutellata and the hybrids combined, and A. m. scutellata workers also dispersed more frequently than the hybrids. Dispersers from queenright A. m. capensis colonies were more often found in queenless host colonies and vice versa, indicating active host searching and/or a queenstate-discriminating guarding mechanism. Our data show that A. m. capensis workers disperse significantly more often than other races of A. mellifera, suggesting that dispersing represents a host finding mechanism. The lack of dispersal in hybrids and different hosting mechanisms of foreign workers by hybrid colonies may also be responsible for the stability of the natural hybrid zone between A. m. capensis and A. m. scutellata.
- Full Text:
- Date Issued: 2001
SoDA : a model for the administration of separation of duty requirements in workflow systems
- Authors: Perelson, Stephen
- Date: 2001
- Subjects: Electronic data processing departments -- Security measures , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MTech (Information Technology)
- Identifier: vital:10796 , http://hdl.handle.net/10948/68 , Electronic data processing departments -- Security measures , Computers -- Access control
- Description: The increasing reliance on information technology to support business processes has emphasised the need for information security mechanisms. This, however, has resulted in an ever-increasing workload in terms of security administration. Security administration encompasses the activity of ensuring the correct enforcement of access control within an organisation. Access rights and their allocation are dictated by the security policies within an organisation. As such, security administration can be seen as a policybased approach. Policy-based approaches promise to lighten the workload of security administrators. Separation of duties is one of the principles cited as a criterion when setting up these policy-based mechanisms. Different types of separation of duty policies exist. They can be categorised into policies that can be enforced at administration time, viz. static separation of duty requirements and policies that can be enforced only at execution time, viz. dynamic separation of duty requirements. This dissertation deals with the specification of both static separation of duty requirements and dynamic separation of duty requirements in role-based workflow environments. It proposes a model for the specification of separation of duty requirements, the expressions of which are based on set theory. The model focuses, furthermore, on the enforcement of static separation of duty. The enforcement of static separation of duty requirements is modelled in terms of invariant conditions. The invariant conditions specify restrictions upon the elements allowed in the sets representing access control requirements. The sets are themselves expressed as database tables within a relational database management system. Algorithms that stipulate how to verify the additions or deletions of elements within these sets can then be performed within the database management system. A prototype was developed in order to demonstrate the concepts of this model. This prototype helps demonstrate how the proposed model could function and flaunts its effectiveness.
- Full Text:
- Date Issued: 2001
- Authors: Perelson, Stephen
- Date: 2001
- Subjects: Electronic data processing departments -- Security measures , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MTech (Information Technology)
- Identifier: vital:10796 , http://hdl.handle.net/10948/68 , Electronic data processing departments -- Security measures , Computers -- Access control
- Description: The increasing reliance on information technology to support business processes has emphasised the need for information security mechanisms. This, however, has resulted in an ever-increasing workload in terms of security administration. Security administration encompasses the activity of ensuring the correct enforcement of access control within an organisation. Access rights and their allocation are dictated by the security policies within an organisation. As such, security administration can be seen as a policybased approach. Policy-based approaches promise to lighten the workload of security administrators. Separation of duties is one of the principles cited as a criterion when setting up these policy-based mechanisms. Different types of separation of duty policies exist. They can be categorised into policies that can be enforced at administration time, viz. static separation of duty requirements and policies that can be enforced only at execution time, viz. dynamic separation of duty requirements. This dissertation deals with the specification of both static separation of duty requirements and dynamic separation of duty requirements in role-based workflow environments. It proposes a model for the specification of separation of duty requirements, the expressions of which are based on set theory. The model focuses, furthermore, on the enforcement of static separation of duty. The enforcement of static separation of duty requirements is modelled in terms of invariant conditions. The invariant conditions specify restrictions upon the elements allowed in the sets representing access control requirements. The sets are themselves expressed as database tables within a relational database management system. Algorithms that stipulate how to verify the additions or deletions of elements within these sets can then be performed within the database management system. A prototype was developed in order to demonstrate the concepts of this model. This prototype helps demonstrate how the proposed model could function and flaunts its effectiveness.
- Full Text:
- Date Issued: 2001
Solvent-free axial ligand substitution in octaphenoxyphthalocyaninato silicon complexes using microwave irradiation
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304830 , vital:58494 , xlink:href="https://journals.sagepub.com/doi/epdf/10.3184/030823401103168974"
- Description: Several axially substituted octaphenoxy silicon phthalocyanines were prepared by condensation of the complexes used as axial ligands with octaphenoxyphthalocyaninato (dichloro) silicon under microwave irradiation.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304830 , vital:58494 , xlink:href="https://journals.sagepub.com/doi/epdf/10.3184/030823401103168974"
- Description: Several axially substituted octaphenoxy silicon phthalocyanines were prepared by condensation of the complexes used as axial ligands with octaphenoxyphthalocyaninato (dichloro) silicon under microwave irradiation.
- Full Text:
- Date Issued: 2001
Some factors governing the water quality of microtidal estuaries in South Africa
- Authors: Allanson, Brian R
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7096 , http://hdl.handle.net/10962/d1012439
- Description: The role of coastal geomorphology and Man-made alterations, including reduced river flow through dam construction, determines, at least in part, the water quality of South African microtidal estuaries. To offer increased understanding of the manner in which these features may modify water quality, a short description of the biogeochemical processes in estuaries is provided. Comment on the present limitations of modelling some of the estuarine processes in South African investigations is given.
- Full Text:
- Date Issued: 2001
- Authors: Allanson, Brian R
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7096 , http://hdl.handle.net/10962/d1012439
- Description: The role of coastal geomorphology and Man-made alterations, including reduced river flow through dam construction, determines, at least in part, the water quality of South African microtidal estuaries. To offer increased understanding of the manner in which these features may modify water quality, a short description of the biogeochemical processes in estuaries is provided. Comment on the present limitations of modelling some of the estuarine processes in South African investigations is given.
- Full Text:
- Date Issued: 2001
Spatial aspects of the reproductive and feeding biology of the striped robber, Brycinus lateralis (Pisces: Characidae), in the Okavango Delta, Botswana
- Booth, Anthony J, McKinlay, Bruce W
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127020 , vital:35944 , https://doi.10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57mmSL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127020 , vital:35944 , https://doi.10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57mmSL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
Spatial aspects of the reproductive and feeding biology of the striped robber, Brycinus lateralis (Pisces: Characidae), in the Okavango Delta, Botswana
- Booth, Anthony J, McKinlay, Bruce W
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
Spectroscopic studies of the interaction of cobalt (II) N, N', N ″, N‴-tetramethyltetra-3, 4-pyridinoporphyrazine with amino acids and nitrogen oxides
- Thamae, Mamothibe A, Nyokong, Tebello
- Authors: Thamae, Mamothibe A , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291617 , vital:56892 , xlink:href="https://doi.org/10.1002/jpp.551"
- Description: The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([CoIItmtppa]4+) is reported. Metal-based autoreduction of [CoIItmtppa]4+ occurs with the formation of the [CoItmtppa(-2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [CoIItmtppa]4+ in the presence of these amino acids gave the rate constants kf = 2.1 × 101 and 2.8 dm3 mol-1 s-1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [CoIItmtppa]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104dm3mol-1 and kf = 7.5 dm3mol-1s-1, respectively. The coordination of nitrite to [CoIItmtppa]4+ occurred with an equilibrium constant of K = 2.0 × 102dm3mol-1 and a rate constant of kf = 4.0 × 10-3dm3mol-1s-1. There was no evidence for the coordination of two molecules of nitrite to the [CoIItmtppa]4+ species.
- Full Text:
- Date Issued: 2001
- Authors: Thamae, Mamothibe A , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291617 , vital:56892 , xlink:href="https://doi.org/10.1002/jpp.551"
- Description: The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([CoIItmtppa]4+) is reported. Metal-based autoreduction of [CoIItmtppa]4+ occurs with the formation of the [CoItmtppa(-2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [CoIItmtppa]4+ in the presence of these amino acids gave the rate constants kf = 2.1 × 101 and 2.8 dm3 mol-1 s-1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [CoIItmtppa]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104dm3mol-1 and kf = 7.5 dm3mol-1s-1, respectively. The coordination of nitrite to [CoIItmtppa]4+ occurred with an equilibrium constant of K = 2.0 × 102dm3mol-1 and a rate constant of kf = 4.0 × 10-3dm3mol-1s-1. There was no evidence for the coordination of two molecules of nitrite to the [CoIItmtppa]4+ species.
- Full Text:
- Date Issued: 2001
Strategies for the improvement of the industrial oxidation of cymene
- Authors: Harmse, Nigel
- Date: 2001
- Subjects: Oxidation , Cymene
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10958 , http://hdl.handle.net/10948/73 , Oxidation , Cymene
- Description: The oxidation of cymene with dioxygen has been investigated in some detail with the view of establishing the feasibility of improving the efficiency of the oxidation process. Of particular interest were the rate of cymene oxidation and the selectivity of the oxidation process for the tertiary cymene hydroperoxide, especially at conversions above 15%. In order to be able to evaluate the selectivity of oxidation processes, a reliable method for analysis of the individual hydroperoxides had to be established. Two methods were investigated, namely reduction of the hydroperoxides to alcohols using ferrous sulphate and reduction using triphenylphosphine, and analysing the reduction products by gas chromatography. Of these two methods, the triphenylphosphine method proved to be superior to the ferrous sulphate method and was used as the method of choice for this investigation. A number of oxidation systems were evaluated in an initial screening experiment for the oxidation of p-cymene. The results of this screening experiment showed that three-phase oxidation systems, i.e. systems containing an organic phase, an aqueous phase and gas, gave significantly lower activities than two-phase oxidation systems. In addition, the use of a base in the aqueous layer does not improve the overall selectivity of the oxidation process, but improves the selectivity towards the tertiary hydroperoxide to some extent due to the decomposition and extraction of primary hydroperoxide into the basic aqueous phase. Oxidation systems using a non-autoxidation catalyst, i.e. a catalyst that does not catalyse the conventional autoxidation of organic compounds, gave by far the most promising results. These systems gave both a high selectivity as well as high reaction rate. From the initial screening experiment, and using multi-factorial statistical techniques, two catalyst systems were selected for investigation, namely vanadium phosphate and boron phosphate. The results of these investigations showed that these two catalysts are remarkably active and selective for the oxidation of p-cymene, giving the cymene tertiary hydroperoxide in selectivities exceeding 85% and at substrate conversions as high as 25%. These results are a considerable improvement over currently known oxidation systems and may offer opportunities for further commercial exploitation.
- Full Text:
- Date Issued: 2001
- Authors: Harmse, Nigel
- Date: 2001
- Subjects: Oxidation , Cymene
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10958 , http://hdl.handle.net/10948/73 , Oxidation , Cymene
- Description: The oxidation of cymene with dioxygen has been investigated in some detail with the view of establishing the feasibility of improving the efficiency of the oxidation process. Of particular interest were the rate of cymene oxidation and the selectivity of the oxidation process for the tertiary cymene hydroperoxide, especially at conversions above 15%. In order to be able to evaluate the selectivity of oxidation processes, a reliable method for analysis of the individual hydroperoxides had to be established. Two methods were investigated, namely reduction of the hydroperoxides to alcohols using ferrous sulphate and reduction using triphenylphosphine, and analysing the reduction products by gas chromatography. Of these two methods, the triphenylphosphine method proved to be superior to the ferrous sulphate method and was used as the method of choice for this investigation. A number of oxidation systems were evaluated in an initial screening experiment for the oxidation of p-cymene. The results of this screening experiment showed that three-phase oxidation systems, i.e. systems containing an organic phase, an aqueous phase and gas, gave significantly lower activities than two-phase oxidation systems. In addition, the use of a base in the aqueous layer does not improve the overall selectivity of the oxidation process, but improves the selectivity towards the tertiary hydroperoxide to some extent due to the decomposition and extraction of primary hydroperoxide into the basic aqueous phase. Oxidation systems using a non-autoxidation catalyst, i.e. a catalyst that does not catalyse the conventional autoxidation of organic compounds, gave by far the most promising results. These systems gave both a high selectivity as well as high reaction rate. From the initial screening experiment, and using multi-factorial statistical techniques, two catalyst systems were selected for investigation, namely vanadium phosphate and boron phosphate. The results of these investigations showed that these two catalysts are remarkably active and selective for the oxidation of p-cymene, giving the cymene tertiary hydroperoxide in selectivities exceeding 85% and at substrate conversions as high as 25%. These results are a considerable improvement over currently known oxidation systems and may offer opportunities for further commercial exploitation.
- Full Text:
- Date Issued: 2001
Stratigraphy and geochemistry of the Makganyene formation, Transvaal supergroup, Northern Cape, South Africa
- Authors: Polteau, Stéphane
- Date: 2001
- Subjects: Geology, Stratigraphic -- South Africa -- Northern Cape , Geochemistry -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5003 , http://hdl.handle.net/10962/d1005616 , Geology, Stratigraphic -- South Africa -- Northern Cape , Geochemistry -- South Africa -- Northern Cape
- Description: The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup of the Northern Cape Province. The Makganyene Formation has diamictite as the main rock type, but siltstone, sandstone, shale, and iron-formations are also present. A glacial origin has been proposed in the past due to the presence of dropstones, faceted and striated pebbles. Typically, the Makganyene Formation contains banded iron-formations interbedded with clastic rocks (shale, siltstone, sandstone and diamictites) at the contact with the underlying iron-formations. This transitional zone is generally overlain by massive or layered diamictites which contain poorly sorted clasts (mainly chert) within a shaly matrix. Striated pebbles have been found during field work, and dropstones have been observed in diamictites and banded iron-formations during the study. The top of the Makganyene Formation contains graded cycles interbedded with diamictites and thin layers of andesitic lavas from the Ongeluk Formation. The basal contact of the Makganyene Formation with the underlying Koegas Subgroup was described as unconformable by previous workers. However field work localised in the Rooinekke area shows a broadly conformable and interbedded contact with the underlying Koegas Subgroup. As described above, banded iron-formations are interbedded with the clastic rocks of the Makganyene Formation. Moreover, boreholes from the Sishen area display the same interbedding at the base of the Makganyene Formation. This suggests that no significant time gap is present in the whole succession between the Ghaap and Postmasburg Group. The Transvaal Supergroup in the Northern Cape displays the following succession : carbonates-BIFs-diamictites/ lava-BIFs-carbonates. The Makganyene Formation is thus at the centre of a symmetrical lithologic succession. Bulk rock compositions show that the diamictites have a similar composition to banded iron-formation with regard to their major element contents. Banded iron-formations acted as a source for the diamictites with carbonates and igneous rocks representing minor components. Differences in bulk composition between the Sishen and Matsap areas emphasize that the source of the diamictite was very localised. The Chemical Index of Alteration (CIA) has been calculated, but since the source dominant rock was iron-formation, this index cannot be usefully applied to the diamictites. ACN, A-CN-K, and A-CNK-FM diagrams confer a major importance in sorting processes due to the separation between the fine and coarse diamictites. The interbedded iron-formations display little clastic contamination indicating deposition in clear water conditions. However, dropstones are present in one borehole from the Matsap area, indicating that iron-formation took place under ice cover, or at least under icebergs. Stable isotope studies show that the iron-formations, interbedded towards the base of the Makganyene Formation, have similar values to the iron-formations of the Koegas Subgroup. As a result of the above observations, new correlations are proposed in this study, relating the different Transvaal Supergroup basins located on the Kaapvaal Craton. The Pretoria Group of the Transvaal Basin has no correlative in the Griqualand West Basin, and the Postmasburg Group of the Northern Cape Basin has no lateral equivalent in the Transvaal Basin. These changes have been made to overcome problems present in the current correlations between those two basins. The Makganyene Formation correlates with the Huronian glaciations which occurred between 2.4 and 2.2 Ga ago in North America. Another Precambrian glaciation is the worldwide and well-studied Neoproterozoic glaciation (640 Ma). At each of these glaciations, major banded iron-formation deposition took place with associated deposition of sedimentary manganese in post-glacial positions. The central position of the Makganyene Formation within the Transvaal Supergroup in the Northern Cape emphasizes this glacial climatic dependence of paleoproterozoic banded iron-formation and manganese deposition. However these two Precambrian glaciations are interpreted in paleomagnetic studies as having occurred near to the equator. The controversial theory of the Snowball Earth has been proposed which proposes that the Earth was entirely frozen from pole to pole. Results from field work, sedimentology, petrography and geochemistry were integrated in a proposed depositional model of the Makganyene Formation occurring at the symmetrical centre of the lithologic succession of the Transvaal Supergroup. At the beginning of the Makganyene glaciation, a regression occurred and glacial advance took place. The diamictites are mostly interpreted as being deposited from wet-based glaciers, probably tidewater glaciers, where significant slumping and debris flows occurred. Any transgression would cause a glacial retreat by rapid calving, re-establishing the chemical sedimentation of banded iron-formations. These sea-level variations are responsible for the interbedding of these different types of rocks (clastic and chemical). The end of the Makganyene glacial event is characterised by subaerial eruptions of andesitic lava of the Ongeluk Formation bringing ashes into the basin. Banded iron-formation and associated manganese accumulations are climate-dependant. Glacial events are responsible for the build up of metallic ions such as iron and manganese in solution in deep waters. A warmer climate would induce a transgression and precipitation of these metallic ions when Eh conditions are favourable. In the Transvaal Supergroup, the climatic variations from warm to cold, and cold to warm are expressed by the lithologic succession. The warm climates are represented by carbonates. Cold climates are represented by banded iron-formations and the peak in cold climate represented by the diamictites of the Makganyene Formation. These changes in climate are gradual, which contradict the dramatic Snowball Earth event: a rapid spread of glaciated areas over low-latitudes freezing the Earth from pole-to-pole. Therefore, to explain low-latitude glaciations at sea-level, a high obliquity of the ecliptic is most likely to have occurred. This high obliquity of the ecliptic was acquired at 4.5 Ga when a giant impactor collided into the Earth to form the Moon. Above the critical value of 54° of the obliquity of the ecliptic, normal climatic zonation reverts, and glaciations will take place preferentially at low-latitudes only when favourable conditions are gathered (relative position ofthe continents and PC02 in the atmosphere).
- Full Text:
- Date Issued: 2001
- Authors: Polteau, Stéphane
- Date: 2001
- Subjects: Geology, Stratigraphic -- South Africa -- Northern Cape , Geochemistry -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5003 , http://hdl.handle.net/10962/d1005616 , Geology, Stratigraphic -- South Africa -- Northern Cape , Geochemistry -- South Africa -- Northern Cape
- Description: The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup of the Northern Cape Province. The Makganyene Formation has diamictite as the main rock type, but siltstone, sandstone, shale, and iron-formations are also present. A glacial origin has been proposed in the past due to the presence of dropstones, faceted and striated pebbles. Typically, the Makganyene Formation contains banded iron-formations interbedded with clastic rocks (shale, siltstone, sandstone and diamictites) at the contact with the underlying iron-formations. This transitional zone is generally overlain by massive or layered diamictites which contain poorly sorted clasts (mainly chert) within a shaly matrix. Striated pebbles have been found during field work, and dropstones have been observed in diamictites and banded iron-formations during the study. The top of the Makganyene Formation contains graded cycles interbedded with diamictites and thin layers of andesitic lavas from the Ongeluk Formation. The basal contact of the Makganyene Formation with the underlying Koegas Subgroup was described as unconformable by previous workers. However field work localised in the Rooinekke area shows a broadly conformable and interbedded contact with the underlying Koegas Subgroup. As described above, banded iron-formations are interbedded with the clastic rocks of the Makganyene Formation. Moreover, boreholes from the Sishen area display the same interbedding at the base of the Makganyene Formation. This suggests that no significant time gap is present in the whole succession between the Ghaap and Postmasburg Group. The Transvaal Supergroup in the Northern Cape displays the following succession : carbonates-BIFs-diamictites/ lava-BIFs-carbonates. The Makganyene Formation is thus at the centre of a symmetrical lithologic succession. Bulk rock compositions show that the diamictites have a similar composition to banded iron-formation with regard to their major element contents. Banded iron-formations acted as a source for the diamictites with carbonates and igneous rocks representing minor components. Differences in bulk composition between the Sishen and Matsap areas emphasize that the source of the diamictite was very localised. The Chemical Index of Alteration (CIA) has been calculated, but since the source dominant rock was iron-formation, this index cannot be usefully applied to the diamictites. ACN, A-CN-K, and A-CNK-FM diagrams confer a major importance in sorting processes due to the separation between the fine and coarse diamictites. The interbedded iron-formations display little clastic contamination indicating deposition in clear water conditions. However, dropstones are present in one borehole from the Matsap area, indicating that iron-formation took place under ice cover, or at least under icebergs. Stable isotope studies show that the iron-formations, interbedded towards the base of the Makganyene Formation, have similar values to the iron-formations of the Koegas Subgroup. As a result of the above observations, new correlations are proposed in this study, relating the different Transvaal Supergroup basins located on the Kaapvaal Craton. The Pretoria Group of the Transvaal Basin has no correlative in the Griqualand West Basin, and the Postmasburg Group of the Northern Cape Basin has no lateral equivalent in the Transvaal Basin. These changes have been made to overcome problems present in the current correlations between those two basins. The Makganyene Formation correlates with the Huronian glaciations which occurred between 2.4 and 2.2 Ga ago in North America. Another Precambrian glaciation is the worldwide and well-studied Neoproterozoic glaciation (640 Ma). At each of these glaciations, major banded iron-formation deposition took place with associated deposition of sedimentary manganese in post-glacial positions. The central position of the Makganyene Formation within the Transvaal Supergroup in the Northern Cape emphasizes this glacial climatic dependence of paleoproterozoic banded iron-formation and manganese deposition. However these two Precambrian glaciations are interpreted in paleomagnetic studies as having occurred near to the equator. The controversial theory of the Snowball Earth has been proposed which proposes that the Earth was entirely frozen from pole to pole. Results from field work, sedimentology, petrography and geochemistry were integrated in a proposed depositional model of the Makganyene Formation occurring at the symmetrical centre of the lithologic succession of the Transvaal Supergroup. At the beginning of the Makganyene glaciation, a regression occurred and glacial advance took place. The diamictites are mostly interpreted as being deposited from wet-based glaciers, probably tidewater glaciers, where significant slumping and debris flows occurred. Any transgression would cause a glacial retreat by rapid calving, re-establishing the chemical sedimentation of banded iron-formations. These sea-level variations are responsible for the interbedding of these different types of rocks (clastic and chemical). The end of the Makganyene glacial event is characterised by subaerial eruptions of andesitic lava of the Ongeluk Formation bringing ashes into the basin. Banded iron-formation and associated manganese accumulations are climate-dependant. Glacial events are responsible for the build up of metallic ions such as iron and manganese in solution in deep waters. A warmer climate would induce a transgression and precipitation of these metallic ions when Eh conditions are favourable. In the Transvaal Supergroup, the climatic variations from warm to cold, and cold to warm are expressed by the lithologic succession. The warm climates are represented by carbonates. Cold climates are represented by banded iron-formations and the peak in cold climate represented by the diamictites of the Makganyene Formation. These changes in climate are gradual, which contradict the dramatic Snowball Earth event: a rapid spread of glaciated areas over low-latitudes freezing the Earth from pole-to-pole. Therefore, to explain low-latitude glaciations at sea-level, a high obliquity of the ecliptic is most likely to have occurred. This high obliquity of the ecliptic was acquired at 4.5 Ga when a giant impactor collided into the Earth to form the Moon. Above the critical value of 54° of the obliquity of the ecliptic, normal climatic zonation reverts, and glaciations will take place preferentially at low-latitudes only when favourable conditions are gathered (relative position ofthe continents and PC02 in the atmosphere).
- Full Text:
- Date Issued: 2001
StreetNet's progress to date and plans for the future
- Authors: StreetNet Association
- Date: 2001
- Subjects: StreetNet Association
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/162170 , vital:40769
- Description: The StreetNet offices were opened in February 2000, eighteen months ago. We are now half-way through our three-year programme to launch StreetNet as an international organisation of street vendors all over the world. tVhat progress has been made in the first eighteen months ? We have two people working part-time in the StreetNet office since February 2000. Pat Horn is the International Co-ordinator while Nozipho Lembethe is the International Administrator. We have been trying unsuccessfully to find a website manager/researcher to start working with us this year.
- Full Text:
- Date Issued: 2001
- Authors: StreetNet Association
- Date: 2001
- Subjects: StreetNet Association
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/162170 , vital:40769
- Description: The StreetNet offices were opened in February 2000, eighteen months ago. We are now half-way through our three-year programme to launch StreetNet as an international organisation of street vendors all over the world. tVhat progress has been made in the first eighteen months ? We have two people working part-time in the StreetNet office since February 2000. Pat Horn is the International Co-ordinator while Nozipho Lembethe is the International Administrator. We have been trying unsuccessfully to find a website manager/researcher to start working with us this year.
- Full Text:
- Date Issued: 2001