The distribution of platinum group elements in the Insizwa lobe, Mount Ayliff Complex, South Africa: implications for Ni-Cu-PGE sulfide exploration in the Karoo igneous province
- Maier, W D, Marsh, Julian S, Barnes, Sarah-Jane, Dodd, D C
- Authors: Maier, W D , Marsh, Julian S , Barnes, Sarah-Jane , Dodd, D C
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150353 , vital:38969 , https://0-doi.org.wam.seals.ac.za/10.2113/gsecongeo.97.6.1293
- Description: The Mount Ayliff Complex of the Eastern Cape province of South Africa is a layered intrusion of some 800 km2 surface area and up to 1,200 m thickness. On the basis of compositional similarities and spatial association, it is generally interpreted to form part of the Karoo igneous province. Similarities between the Mount Ayliff Complex and the staging chambers and feeder conduits to flood basalts that host magmatic sulfide ores elsewhere in the world suggest that the Mount Ayliff Complex may have an enhanced potential for Noril’sk-Talnakh–type massive Ni-Cu sulfide ores, an idea that is supported by the well-known sulfide occurrence at Waterfall Gorge.
- Full Text: false
- Date Issued: 2002
- Authors: Maier, W D , Marsh, Julian S , Barnes, Sarah-Jane , Dodd, D C
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150353 , vital:38969 , https://0-doi.org.wam.seals.ac.za/10.2113/gsecongeo.97.6.1293
- Description: The Mount Ayliff Complex of the Eastern Cape province of South Africa is a layered intrusion of some 800 km2 surface area and up to 1,200 m thickness. On the basis of compositional similarities and spatial association, it is generally interpreted to form part of the Karoo igneous province. Similarities between the Mount Ayliff Complex and the staging chambers and feeder conduits to flood basalts that host magmatic sulfide ores elsewhere in the world suggest that the Mount Ayliff Complex may have an enhanced potential for Noril’sk-Talnakh–type massive Ni-Cu sulfide ores, an idea that is supported by the well-known sulfide occurrence at Waterfall Gorge.
- Full Text: false
- Date Issued: 2002
The concentrations of the noble metals in Southern African flood-type basalts and MORB: implications for petrogenesis and magmatic sulphide exploration
- Maier, Wolfgand D, Barnes, Sarah-Jane, Marsh, Julian S
- Authors: Maier, Wolfgand D , Barnes, Sarah-Jane , Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150573 , vital:38985 , https://doi.org/10.1007/s00410-003-0480-z
- Description: Concentrations of the platinum-group elements have been determined in several suites of southern African flood-type basalts and mid-ocean ridge basalt (MORB), covering some 3 Ga of geologic evolution and including the Etendeka, Karoo, Soutpansberg, Machadodorp, Hekpoort, Ventersdorp and Dominion magmas.
- Full Text: false
- Date Issued: 2003
- Authors: Maier, Wolfgand D , Barnes, Sarah-Jane , Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150573 , vital:38985 , https://doi.org/10.1007/s00410-003-0480-z
- Description: Concentrations of the platinum-group elements have been determined in several suites of southern African flood-type basalts and mid-ocean ridge basalt (MORB), covering some 3 Ga of geologic evolution and including the Etendeka, Karoo, Soutpansberg, Machadodorp, Hekpoort, Ventersdorp and Dominion magmas.
- Full Text: false
- Date Issued: 2003
The inhibitory effects of various substrate pre-treatment by-products and wash liquors on mannanolytic enzymes
- Malgas, Samkelo, Van Dyk, J Susan, Abboo, Sagaran, Pletschke, Brett I
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
Regulatory incoherence and economic potential of freshwater recreational fisheries: the trout triangle in South Africa
- Marire, Juniours, Snowball, Jeanette D, Fraser, Gavin C G
- Authors: Marire, Juniours , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68621 , vital:29295 , https://www.tandfonline.com/doi/abs/10.2753/JEI0021-3624480406
- Description: Publisher version , We apply John R. Commons’s negotiational psychology, specifically his principle of sovereignty, to the development of a discordant regulatory culture and its likely impact on the economic potential of recreational fishing. Using South African environmental judicial precedents and other documentation, we formulate six plausible hypotheses. We argue that regulatory incoherence, entitlement insecurity, corporate-dominated social valuation, strategic power coalitions, lack of procedural fairness, and the extent of judicial enforcement of environmental rights help explain the economic potential and isolation of the freshwater recreational fisheries sector. We find a consistent pattern of extraction and monopolization of sovereign power by the Department of Mineral Resources from propertied parties. Thus, regulatory domination is a major mechanism affecting the economic potential of recreational fisheries in the Trout Triangle. While Commons postulated that private property is a sufficient condition for participation in the determination and use of sovereign power, we argue that private/public property is only a necessary condition. The conjunctive sufficient condition is the existence of both regulatory coherence between spheres of government and property.
- Full Text: false
- Date Issued: 2014
- Authors: Marire, Juniours , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68621 , vital:29295 , https://www.tandfonline.com/doi/abs/10.2753/JEI0021-3624480406
- Description: Publisher version , We apply John R. Commons’s negotiational psychology, specifically his principle of sovereignty, to the development of a discordant regulatory culture and its likely impact on the economic potential of recreational fishing. Using South African environmental judicial precedents and other documentation, we formulate six plausible hypotheses. We argue that regulatory incoherence, entitlement insecurity, corporate-dominated social valuation, strategic power coalitions, lack of procedural fairness, and the extent of judicial enforcement of environmental rights help explain the economic potential and isolation of the freshwater recreational fisheries sector. We find a consistent pattern of extraction and monopolization of sovereign power by the Department of Mineral Resources from propertied parties. Thus, regulatory domination is a major mechanism affecting the economic potential of recreational fisheries in the Trout Triangle. While Commons postulated that private property is a sufficient condition for participation in the determination and use of sovereign power, we argue that private/public property is only a necessary condition. The conjunctive sufficient condition is the existence of both regulatory coherence between spheres of government and property.
- Full Text: false
- Date Issued: 2014
Distribution of Ca in highly fractionated peralkaline magmas
- Authors: Marsh, Julian S
- Date: 1976
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132974 , vital:36914 , https://doi.org/10.1016/0012-821X(76)90106-0
- Description: Many peralkaline rhyolites and granites contain less than 0.15 wt.% CaO. In contrast, strongly fractionated peralkaline nepheline syenites and phonolites usually contain greater than 0.5 wt.% CaO. Consideration of known distributions of Ca between crystals and liquid in conjunction with crystal fractionation does not provide an adequate explanation of the contrasting levels of Ca depletion observed. Examination of the suites of late-crystallizing accessory phases in peralkaline rocks suggests that Ca is more soluble in undersaturated magmas than in over-saturated magmas. Activities for CaO in silicic and phonolitic rocks are calculated and the latter have higher CaO activities than the former and this may manifest itself in the different suites of accessory phases and levels of Ca depletion noted in natural rocks.
- Full Text: false
- Date Issued: 1976
- Authors: Marsh, Julian S
- Date: 1976
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132974 , vital:36914 , https://doi.org/10.1016/0012-821X(76)90106-0
- Description: Many peralkaline rhyolites and granites contain less than 0.15 wt.% CaO. In contrast, strongly fractionated peralkaline nepheline syenites and phonolites usually contain greater than 0.5 wt.% CaO. Consideration of known distributions of Ca between crystals and liquid in conjunction with crystal fractionation does not provide an adequate explanation of the contrasting levels of Ca depletion observed. Examination of the suites of late-crystallizing accessory phases in peralkaline rocks suggests that Ca is more soluble in undersaturated magmas than in over-saturated magmas. Activities for CaO in silicic and phonolitic rocks are calculated and the latter have higher CaO activities than the former and this may manifest itself in the different suites of accessory phases and levels of Ca depletion noted in natural rocks.
- Full Text: false
- Date Issued: 1976
REE fractionation and Ce anomalies in weathered Karoo dolerite
- Authors: Marsh, Julian S
- Date: 1991
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145819 , vital:38469 , https://doi.org/10.1016/0009-2541(91)90099-D
- Description: Analyses of samples from a weathering profile on Karoo dolerite allow elements to be divided into three groups depending on their behaviour. Si, K, Na, Mg, Ca, Sr, Ba and V are mobilized and removed from weathered products. Fe, Al. Ti, Zr, Hf, Zn, Cu, Sc, Co and Ni are immobile. REE, Y, and to a lesser extent Cr, are mobile and redistributed within the profile without a net loss of these elements from the profile. Large positive Ce anomalies are developed in oxidized weathered products by preferential leaching of the other REE's. Negative Ce anomalies and REE enrichment is a feature of less altered dolerite.
- Full Text: false
- Date Issued: 1991
- Authors: Marsh, Julian S
- Date: 1991
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145819 , vital:38469 , https://doi.org/10.1016/0009-2541(91)90099-D
- Description: Analyses of samples from a weathering profile on Karoo dolerite allow elements to be divided into three groups depending on their behaviour. Si, K, Na, Mg, Ca, Sr, Ba and V are mobilized and removed from weathered products. Fe, Al. Ti, Zr, Hf, Zn, Cu, Sc, Co and Ni are immobile. REE, Y, and to a lesser extent Cr, are mobile and redistributed within the profile without a net loss of these elements from the profile. Large positive Ce anomalies are developed in oxidized weathered products by preferential leaching of the other REE's. Negative Ce anomalies and REE enrichment is a feature of less altered dolerite.
- Full Text: false
- Date Issued: 1991
Petrogenesis of late Archaean flood-type basic lavas from the Klipriviersberg Group, Ventersdorp Supergroup, South Africa
- Marsh, Julian S, Bowen, M P, Rogers, N W, Bowen, T B
- Authors: Marsh, Julian S , Bowen, M P , Rogers, N W , Bowen, T B
- Date: 1992
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145829 , vital:38470 , https://doi.org/10.1093/petrology/33.4.817
- Description: The Klipriviersberg Group is a small continental flood-type tholeiitic suite forming the basal unit of the Ventersdorp Supergroup, an undeformed late-Archaean supracrustal sequence covering 200000 km2 in the SW part of the Kaapvaal Craton. From the base up, the Klipriviersberg Group consists of the Westonaria, Alberton, Orkney, Jeannette, Loraine, and Edenville formations, with a maximum combined thickness of 1–8 km. Samples were obtained from several borehole cores in the Klerksdorp goldfield close to the type area of the Klipriviersberg Group.
- Full Text: false
- Date Issued: 1992
- Authors: Marsh, Julian S , Bowen, M P , Rogers, N W , Bowen, T B
- Date: 1992
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145829 , vital:38470 , https://doi.org/10.1093/petrology/33.4.817
- Description: The Klipriviersberg Group is a small continental flood-type tholeiitic suite forming the basal unit of the Ventersdorp Supergroup, an undeformed late-Archaean supracrustal sequence covering 200000 km2 in the SW part of the Kaapvaal Craton. From the base up, the Klipriviersberg Group consists of the Westonaria, Alberton, Orkney, Jeannette, Loraine, and Edenville formations, with a maximum combined thickness of 1–8 km. Samples were obtained from several borehole cores in the Klerksdorp goldfield close to the type area of the Klipriviersberg Group.
- Full Text: false
- Date Issued: 1992
The geochemical structure of the Insizwa lobe of the Mount Ayliff complex with implications for the emplacement and evolution of the complex and its Ni-sulphide potential
- Marsh, Julian S, Allen, P, Fenner, N
- Authors: Marsh, Julian S , Allen, P , Fenner, N
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150556 , vital:38984 , https://doi.org/10.2113/106.4.409
- Description: Detailed petrographic, modal and geochemical studies on a number of deep boreholes (exceeding 1.2 km in some instances) along the southeastern margin of the Insizwa lobe of the Mount Ayliff Complex reveal the existence of a geochemical stratigraphy in the mafic intrusive rocks.
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S , Allen, P , Fenner, N
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150556 , vital:38984 , https://doi.org/10.2113/106.4.409
- Description: Detailed petrographic, modal and geochemical studies on a number of deep boreholes (exceeding 1.2 km in some instances) along the southeastern margin of the Insizwa lobe of the Mount Ayliff Complex reveal the existence of a geochemical stratigraphy in the mafic intrusive rocks.
- Full Text: false
- Date Issued: 2003
Geochemical constraints on coupled assimilation and fractional crystallization involving upper crustal compositions and continental tholeiitic magma
- Authors: Marsh, Julian S
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140432 , vital:37888 , https://doi.org/10.1016/0012-821X(89)90021-6
- Description: The commonly analyzed trace elements in tholeiites can be subdivided into three groups depending on their sense of enrichment or depletion in upper continental crust in relation to fractional crystallization. Lithophile incompatible elements are enriched in crustal rocks and by fractional crystallization, whereas compatible transition elements such as Ni and Cr are depleted. A small third group comprising Ti, V, Fe, and sometimes P, enrich with crystallization but are depleted in the crust.
- Full Text: false
- Date Issued: 2002
- Authors: Marsh, Julian S
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140432 , vital:37888 , https://doi.org/10.1016/0012-821X(89)90021-6
- Description: The commonly analyzed trace elements in tholeiites can be subdivided into three groups depending on their sense of enrichment or depletion in upper continental crust in relation to fractional crystallization. Lithophile incompatible elements are enriched in crustal rocks and by fractional crystallization, whereas compatible transition elements such as Ni and Cr are depleted. A small third group comprising Ti, V, Fe, and sometimes P, enrich with crystallization but are depleted in the crust.
- Full Text: false
- Date Issued: 2002
Volcanic rocks of the Witwatersrand Triad, South Africa. II: petrogenesis of mafic and felsic rocks of the Dominion Group
- Marsh, Julian S, Bowen, M P, Rogers, N W, Bowen, T B
- Authors: Marsh, Julian S , Bowen, M P , Rogers, N W , Bowen, T B
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140443 , vital:37889 , https://doi.org/10.1016/0301-9268(89)90075-2
- Description: A bimodal suite of volcanic rocks builds the bulk of the Dominion Group which, with an age of ∼ 2.72 Ga, is the oldest cover sequence overlying the granite-greenstone Archaean basement of the Kaapvaal craton in the western Transvaal, South Africa. The basic lavas are relatively rich in SiO2 (50–58%) and aphyric and exhibit a large compositional range. This variation is typically tholeiitic in that it is characterized by strong enrichment of Ti, Fe, and V in differentiated lavas.
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S , Bowen, M P , Rogers, N W , Bowen, T B
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140443 , vital:37889 , https://doi.org/10.1016/0301-9268(89)90075-2
- Description: A bimodal suite of volcanic rocks builds the bulk of the Dominion Group which, with an age of ∼ 2.72 Ga, is the oldest cover sequence overlying the granite-greenstone Archaean basement of the Kaapvaal craton in the western Transvaal, South Africa. The basic lavas are relatively rich in SiO2 (50–58%) and aphyric and exhibit a large compositional range. This variation is typically tholeiitic in that it is characterized by strong enrichment of Ti, Fe, and V in differentiated lavas.
- Full Text: false
- Date Issued: 2003
Basalt geochemistry and tectonic discrimination within continental flood basalt provinces
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140412 , vital:37886 , https://doi.org/10.1016/0377-0273(87)90035-7
- Description: Continental flood basalts are usually regarded as a single tectonomagmatic entity but frequently quoted examples exhibit a variety of tectonic settings. In one well-studied, classic, flood basalt province, the Mesozoic Karoo province of southern Africa, magmatism occurred in the following tectonic settings: (a) continental rifting leading to ocean-floor spreading in the South Atlantic Ocean (Etendeka suite of Namibia); (b) stretched continental lithosphere and rifting not leading directly to ocean-floor formation (Lebombo suite of southeastern Africa); and (c) an a-tectonic, within-plate, continental setting characterized by an absence of faulting or warping (Lesotho highlands and Karoo dolerites of South Africa).
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140412 , vital:37886 , https://doi.org/10.1016/0377-0273(87)90035-7
- Description: Continental flood basalts are usually regarded as a single tectonomagmatic entity but frequently quoted examples exhibit a variety of tectonic settings. In one well-studied, classic, flood basalt province, the Mesozoic Karoo province of southern Africa, magmatism occurred in the following tectonic settings: (a) continental rifting leading to ocean-floor spreading in the South Atlantic Ocean (Etendeka suite of Namibia); (b) stretched continental lithosphere and rifting not leading directly to ocean-floor formation (Lebombo suite of southeastern Africa); and (c) an a-tectonic, within-plate, continental setting characterized by an absence of faulting or warping (Lesotho highlands and Karoo dolerites of South Africa).
- Full Text: false
- Date Issued: 2003
The Etendeka Igneous Province: magma types and their stratigraphic distribution with implications for the evolution of the Paraná-Etendeka flood basalt province
- Marsh, Julian S, Ewart, A, Milner, Simon C, Duncan, Andrew R, Miller, R McG
- Authors: Marsh, Julian S , Ewart, A , Milner, Simon C , Duncan, Andrew R , Miller, R McG
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149762 , vital:38882 , https://doi.org/10.1007/s004450000115
- Description: Detailed geochemical and field data for the volcanic sequence and intrusions of the Etendeka Igneous Province are used to construct a stratigraphic framework for petrogenetic interpretation of the evolution of the Etendeka-Paraná continental flood volcanic event. Geochemical and petrographic characterization of over 1,000 analyzed samples allows 8 mafic and 17 silicic magma types to be recognized.
- Full Text: false
- Date Issued: 2017
- Authors: Marsh, Julian S , Ewart, A , Milner, Simon C , Duncan, Andrew R , Miller, R McG
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149762 , vital:38882 , https://doi.org/10.1007/s004450000115
- Description: Detailed geochemical and field data for the volcanic sequence and intrusions of the Etendeka Igneous Province are used to construct a stratigraphic framework for petrogenetic interpretation of the evolution of the Etendeka-Paraná continental flood volcanic event. Geochemical and petrographic characterization of over 1,000 analyzed samples allows 8 mafic and 17 silicic magma types to be recognized.
- Full Text: false
- Date Issued: 2017
Implications of a new 40Ar/ 39Ar age for a basalt flow interbedded with the Etjo Formation, Northeast Namibia
- Marsh, Julian S, Swart, Roger S, Phillips, D
- Authors: Marsh, Julian S , Swart, Roger S , Phillips, D
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150364 , vital:38970 , https://doi.org/10.2113/106.4.281
- Description: A reliable 40Ar/39Ar plateau age of 180 ± 1.2 Ma (1σ) has been obtained for fresh basalt lava interbedded with aeolian Etjo Formation sandstones south-southwest of Grootfontein in northeast Namibia. This indicates that the Early Jurassic Karoo flood basalt sequence extended from Botswana into northeast Namibia at least as far as 18 east and that this may mark the eastern extent of the Early Cretaceous Etendeka Igneous Province.
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S , Swart, Roger S , Phillips, D
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150364 , vital:38970 , https://doi.org/10.2113/106.4.281
- Description: A reliable 40Ar/39Ar plateau age of 180 ± 1.2 Ma (1σ) has been obtained for fresh basalt lava interbedded with aeolian Etjo Formation sandstones south-southwest of Grootfontein in northeast Namibia. This indicates that the Early Jurassic Karoo flood basalt sequence extended from Botswana into northeast Namibia at least as far as 18 east and that this may mark the eastern extent of the Early Cretaceous Etendeka Igneous Province.
- Full Text: false
- Date Issued: 2003
Evolution of a strongly differentiated suite of phonolites from the Klinghardt Mountains, Namibia
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140400 , vital:37885 , https://doi.org/10.1016/0024-4937(87)90023-5
- Description: Phonolites of Tertiary age occur as eroded tholoids, lava flows, ignimbrites, and coulees in the Klinghardt Mountains of southern Namibia. Sixty samples have been analyzed for major and trace elements and fourteen of these for 87SR 86SR. The phonolites lie close to the low-pressure cotectics in Q-Ne-Ks, in keeping with their petrography which indicates that most samples have phenocrysts of both nepheline and sanidine. Na has been variably lost from the rocks during crystallization and devitrification/alteration of hypocrystalline specimens.
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140400 , vital:37885 , https://doi.org/10.1016/0024-4937(87)90023-5
- Description: Phonolites of Tertiary age occur as eroded tholoids, lava flows, ignimbrites, and coulees in the Klinghardt Mountains of southern Namibia. Sixty samples have been analyzed for major and trace elements and fourteen of these for 87SR 86SR. The phonolites lie close to the low-pressure cotectics in Q-Ne-Ks, in keeping with their petrography which indicates that most samples have phenocrysts of both nepheline and sanidine. Na has been variably lost from the rocks during crystallization and devitrification/alteration of hypocrystalline specimens.
- Full Text: false
- Date Issued: 2003
Aenigmatite stability in silica-undersaturated rocks
- Authors: Marsh, Julian Saville
- Date: 1975
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132942 , vital:36911 , https://doi.org/10.1007/BF00373333
- Description: Aenigmatite is common in many trachytes, phonolites and agpaitic nepheline syenites. Petrographic evidence suggests that the aenigmatite in these rocks arises by the reaction of Ti-magnetite with a peralkaline silica-undersaturated liquid, and it is postulated that a no-oxide field, where aenigmatite is stable, exists in alkaline undersaturated magmas.
- Full Text: false
- Date Issued: 1975
- Authors: Marsh, Julian Saville
- Date: 1975
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132942 , vital:36911 , https://doi.org/10.1007/BF00373333
- Description: Aenigmatite is common in many trachytes, phonolites and agpaitic nepheline syenites. Petrographic evidence suggests that the aenigmatite in these rocks arises by the reaction of Ti-magnetite with a peralkaline silica-undersaturated liquid, and it is postulated that a no-oxide field, where aenigmatite is stable, exists in alkaline undersaturated magmas.
- Full Text: false
- Date Issued: 1975
Invaded habitat incompatibility affects the suitability of the potential biological control agent Listronotus sordidus for Sagittaria platyphylla in South Africa
- Martin, Grant D, Coetzee, Julie A, Lloyd, Melissa, Nombewu, Sinoxolo E, Ndlovu, Mpilonhle S, Kwong, Raelene M
- Authors: Martin, Grant D , Coetzee, Julie A , Lloyd, Melissa , Nombewu, Sinoxolo E , Ndlovu, Mpilonhle S , Kwong, Raelene M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103926 , vital:32323 , https://doi.org/10.1080/09583157.2018.1460314
- Description: Sagittaria platyphylla (Engelmann) J.G. Smith (Alismataceae) was first recorded in South Africa in 2008 and is considered to be an emerging weed with naturalised populations occurring throughout the country. A biological control programme was initiated in Australia and surveys conducted between 2010 and 2012 yielded potential agents, including the crown feeding weevil, Listronotus sordidus Gyllenhal (Coleoptera: Curculionidae). The potential of L. sordidus as a candidate biological control agent against S. platyphylla in South Africa was examined. Although adult feeding was recorded on a number of plant species, oviposition and larval development indicated a narrow host range restricted to the Alismataceae. In South Africa, S. platyphylla populations are primarily found in inundated systems. However, laboratory studies showed that L. sordidus did not oviposit on inundated plants, potentially nullifying the impact of the insect on South African populations. It is suggested that even though L. sordidus is a damaging, specific agent, its limited impact on inundated plant populations in South Africa does not justify the inherent risk associated with the release of a biological control agent.
- Full Text: false
- Date Issued: 2018
- Authors: Martin, Grant D , Coetzee, Julie A , Lloyd, Melissa , Nombewu, Sinoxolo E , Ndlovu, Mpilonhle S , Kwong, Raelene M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103926 , vital:32323 , https://doi.org/10.1080/09583157.2018.1460314
- Description: Sagittaria platyphylla (Engelmann) J.G. Smith (Alismataceae) was first recorded in South Africa in 2008 and is considered to be an emerging weed with naturalised populations occurring throughout the country. A biological control programme was initiated in Australia and surveys conducted between 2010 and 2012 yielded potential agents, including the crown feeding weevil, Listronotus sordidus Gyllenhal (Coleoptera: Curculionidae). The potential of L. sordidus as a candidate biological control agent against S. platyphylla in South Africa was examined. Although adult feeding was recorded on a number of plant species, oviposition and larval development indicated a narrow host range restricted to the Alismataceae. In South Africa, S. platyphylla populations are primarily found in inundated systems. However, laboratory studies showed that L. sordidus did not oviposit on inundated plants, potentially nullifying the impact of the insect on South African populations. It is suggested that even though L. sordidus is a damaging, specific agent, its limited impact on inundated plant populations in South Africa does not justify the inherent risk associated with the release of a biological control agent.
- Full Text: false
- Date Issued: 2018
Structural and optical properties of sol-gel derived α-Fe2O3 nanoparticles
- Mathevula, Langutani E, Noto, L L, Mothudi, Bakang M, Chithambo, Makaiko L, Dhlamini, M S
- Authors: Mathevula, Langutani E , Noto, L L , Mothudi, Bakang M , Chithambo, Makaiko L , Dhlamini, M S
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115467 , vital:34145 , DOI: 10.1016/j.jlumin.2017.07.055
- Description: α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5 nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300 °C and 600 °C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3 eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422 nm when excited by a 336 nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576 nm peak, which was quenched as the temperature increased from 300 °C to 600 °C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315 Gy). The activation energy of the trapped electrons was determined.
- Full Text: false
- Date Issued: 2017
- Authors: Mathevula, Langutani E , Noto, L L , Mothudi, Bakang M , Chithambo, Makaiko L , Dhlamini, M S
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115467 , vital:34145 , DOI: 10.1016/j.jlumin.2017.07.055
- Description: α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5 nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300 °C and 600 °C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3 eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422 nm when excited by a 336 nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576 nm peak, which was quenched as the temperature increased from 300 °C to 600 °C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315 Gy). The activation energy of the trapped electrons was determined.
- Full Text: false
- Date Issued: 2017
HOP expression is regulated by p53 and RAS and characteristic of a cancer gene signature
- Mattison, Stacey A, Blatch, Gregory L, Edkins, Adrienne L
- Authors: Mattison, Stacey A , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66278 , vital:28928 , https://doi.org/10.1007/s12192-016-0755-8
- Description: publisher version , The Hsp70/Hsp90 organising protein (HOP) is a co-chaperone essential for client protein transfer from Hsp70 to Hsp90 within the Hsp90 chaperone machine. Although HOP is upregulated in various cancers, there is limited information from in vitro studies on how HOP expression is regulated in cancer. The main objective of this study was to identify the HOP promoter and investigate its activity in cancerous cells. Bioinformatic analysis of the -2500 to +16 bp region of the HOP gene identified a large CpG island and a range of putative cis-elements. Many of the cis-elements were potentially bound by transcription factors which are activated by oncogenic pathways. Luciferase reporter assays demonstrated that the upstream region of the HOP gene contains an active promoter in vitro. Truncation of this region suggested that the core HOP promoter region was -855 to +16 bp. HOP promoter activity was highest in Hs578T, HEK293T and SV40- transformed MEF1 cell lines which expressed mutant or inactive p53. In a mutant p53 background, expression of wild-type p53 led to a reduction in promoter activity, while inhibition of wild-type p53 in HeLa cells increased HOP promoter activity. Additionally, in Hs578T and HEK293T cell lines containing inactive p53, expression of HRAS increased HOP promoter activity. However, HRAS activation of the HOP promoter was inhibited by p53 overexpression. These findings suggest for the first time that HOP expression in cancer may be regulated by both RAS activation and p53 inhibition. Taken together, these data suggest that HOP may be part of the cancer gene signature induced by a combination of mutant p53 and mutated RAS that is associated with cellular transformation.
- Full Text: false
- Date Issued: 2018
- Authors: Mattison, Stacey A , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66278 , vital:28928 , https://doi.org/10.1007/s12192-016-0755-8
- Description: publisher version , The Hsp70/Hsp90 organising protein (HOP) is a co-chaperone essential for client protein transfer from Hsp70 to Hsp90 within the Hsp90 chaperone machine. Although HOP is upregulated in various cancers, there is limited information from in vitro studies on how HOP expression is regulated in cancer. The main objective of this study was to identify the HOP promoter and investigate its activity in cancerous cells. Bioinformatic analysis of the -2500 to +16 bp region of the HOP gene identified a large CpG island and a range of putative cis-elements. Many of the cis-elements were potentially bound by transcription factors which are activated by oncogenic pathways. Luciferase reporter assays demonstrated that the upstream region of the HOP gene contains an active promoter in vitro. Truncation of this region suggested that the core HOP promoter region was -855 to +16 bp. HOP promoter activity was highest in Hs578T, HEK293T and SV40- transformed MEF1 cell lines which expressed mutant or inactive p53. In a mutant p53 background, expression of wild-type p53 led to a reduction in promoter activity, while inhibition of wild-type p53 in HeLa cells increased HOP promoter activity. Additionally, in Hs578T and HEK293T cell lines containing inactive p53, expression of HRAS increased HOP promoter activity. However, HRAS activation of the HOP promoter was inhibited by p53 overexpression. These findings suggest for the first time that HOP expression in cancer may be regulated by both RAS activation and p53 inhibition. Taken together, these data suggest that HOP may be part of the cancer gene signature induced by a combination of mutant p53 and mutated RAS that is associated with cellular transformation.
- Full Text: false
- Date Issued: 2018
Ferrocenyl and organic novobiocin derivatives: synthesis and their in vitro biological activity
- Mbaba, Mziyanda, Mabhula, Amanda N, Boel, Natasha, Edkins, Adrienne L, Isaacs, Michelle, Hoppe, Heinrich C, Khanye, Setshaba D
- Authors: Mbaba, Mziyanda , Mabhula, Amanda N , Boel, Natasha , Edkins, Adrienne L , Isaacs, Michelle , Hoppe, Heinrich C , Khanye, Setshaba D
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66189 , vital:28914 , https://doi.org/10.1016/j.jinorgbio.2017.04.014
- Description: publisher version , A focused series of novobiocin derivatives containing a ferrocene unit together with their corresponding organic novobiocin analogues have been synthesized in modest to good yields. These compounds were screened for biological activity against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) and human breast cancer cell line (HCC38). With the exception of compounds 5c and 5d, the general trend observed is that incorporation of the ferrocene moiety into novobiocin scaffold resulted in compounds 6a–d/6f showing enhanced activity compared to organic analogues 5a–b and 5e–f.
- Full Text: false
- Date Issued: 2017
- Authors: Mbaba, Mziyanda , Mabhula, Amanda N , Boel, Natasha , Edkins, Adrienne L , Isaacs, Michelle , Hoppe, Heinrich C , Khanye, Setshaba D
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66189 , vital:28914 , https://doi.org/10.1016/j.jinorgbio.2017.04.014
- Description: publisher version , A focused series of novobiocin derivatives containing a ferrocene unit together with their corresponding organic novobiocin analogues have been synthesized in modest to good yields. These compounds were screened for biological activity against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) and human breast cancer cell line (HCC38). With the exception of compounds 5c and 5d, the general trend observed is that incorporation of the ferrocene moiety into novobiocin scaffold resulted in compounds 6a–d/6f showing enhanced activity compared to organic analogues 5a–b and 5e–f.
- Full Text: false
- Date Issued: 2017
Treatment of wine distillery wastewater by high rate anaerobic digestion
- Melamane, Xolisa L, Tandlich, Roman, Burgess, Jo E
- Authors: Melamane, Xolisa L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75896 , vital:30480 , https://doi.org/10.2166/wst.2007.466
- Description: Wine distillery wastewaters (WDW) are acidic and have a high content of potential organic pollutants. This causes high chemical oxygen demand (COD) values. Polyphenols constitute a significant portion of this COD, and limit the efficiency of biological treatment of WDWs. WDW starting parameters were as follows: pH 3.83, 4,185 mg/l soluble COD (CODs) and 674.6 mg/l of phenols. During operation, amendments of CaCO3 and K2HPO4, individually or in combination, were required for buffering the digester.
- Full Text: false
- Date Issued: 2007
- Authors: Melamane, Xolisa L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75896 , vital:30480 , https://doi.org/10.2166/wst.2007.466
- Description: Wine distillery wastewaters (WDW) are acidic and have a high content of potential organic pollutants. This causes high chemical oxygen demand (COD) values. Polyphenols constitute a significant portion of this COD, and limit the efficiency of biological treatment of WDWs. WDW starting parameters were as follows: pH 3.83, 4,185 mg/l soluble COD (CODs) and 674.6 mg/l of phenols. During operation, amendments of CaCO3 and K2HPO4, individually or in combination, were required for buffering the digester.
- Full Text: false
- Date Issued: 2007