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Ini ndakuenda mai

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A preliminary appraisal of the mineral potential of Venda based on a reconnaissance geochemical soil sampling survey and literature review

  • Authors: Wilson, Michael George Carey
  • Date: 1990
  • Subjects: Mines and mineral resources -- South Africa -- Venda
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4994 , http://hdl.handle.net/10962/d1005606 , Mines and mineral resources -- South Africa -- Venda
  • Description: A reconnaissance soil sampling survey was carried out over Venda by Cycad (Pty) Ltd and the samples were analysed for 36 elements using XRF techniques, by Anglo American Research Laboratories in Johanuesburg. The data resulting from this survey forms the basis for the present interpretive study. Initially the sample positions were co-ordinated, then the geological, soil and sample types were allocated to each point. Twelve lithological groupings were chosen which incorporated most of the available data, retained significant geological characteristics and consisted of statistically significant sample populations. Statistical manipulation was undertaken for each of the lithological groups. Using a final population of 5768 samples, means were determined and anomalous values were identified using a threshold of mean plus two standard deviations. Due to time and budgetary constraints, 24 of the 36 elements were chosen for statisical manipulation and fourteen of these, with particular economic significance, were chosen for plotting, wherever significant numbers of anomalies were present. The element overlays were plotted so as to coincide with 18 of the 25, 1:50 000 topographic sheets covering Venda , the remaining 7 having inadequate sample coverage to yield meaningful contours. In this way a total of 175 element overlay sheets were plotted, each showing contoured element levels, with selected anomalous values. The treatment of the vast body of information made available by the Cycad sampling programme has thus been selective and has continually been aimed at highlighting and concentrating attention on the areas of greatest indicated mineralization potential, rather than on specific anomalies. In this regard it is felt that the present study has been successful, in spite of limited sample coverage in some areas. Combining the results of this study with a modern tectonically-based appraisal of mineralization potential and a knowledge of the local geology and previously known mineralization gleaned from an extensive literature review, the following types of mineralization are considered to have the highest potential in Venda: i) Nickel-copper-platinum mineralization as well as magnesite, in the olivine dolerite sills which intrude the base of the Karoo Sequence in Northern Venda. ii) Coal in the basal Karoo Sequence sediments in a broad zone from Jazz 715 MS in the west, and along the Klein Tshipise fault from Amonda 159 MT to the Mutale Copper Fields then east of these to the Kruger National Park. Where intrusives invade these lower Karoo sed iments the potential exists for amorphous graphite. iii) Hydrothermal copper and possibly gold and silver concentrations, in Nzhelele and Sibasa Formation rocks, particularly those associated with faults known to have been active in post-Soutpansberg times. iv) Sediment-hosted massive sulphide deposits (Cu-Pb -Zn) close to basin margin faults, near intersections with cross cutting faults that have resulted in localized basin formation. These are most likely in the Soutpansberg sediments. v) Martle, flake-graphite and late stage skarn mineralization (including lead, zinc, gold and tungsten), in calcareous rocks of the Gumbu Formation.
  • Full Text:
  • Date Issued: 1990

Synthetic and spectrometric investigation of 1,4-benzoxazepines

  • Authors: Whittal, R D
  • Date: 1990
  • Subjects: Spectrum analysis , Benzodiazepines
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4381 , http://hdl.handle.net/10962/d1005046
  • Description: Flavanone (2,3-dihydro-2-phenyl-4H-benzopyran-4-one) and a series of 4'- and 7-halogeno derivatives were prepared from the corresponding 2'-hydroxychalcones [1-(2-hydroxyphenyl)-3-phenyl-2-propen-l-ones], which, in turn, were synthesized by aldol condensation of substituted 2'-hydroxacetophenones with various benzaldehydes. A series of 2,3-dihydro-2-phenyl-l,4-benzoxazepin-5(4H)-ones were prepared by ring expansion of the corresponding flavanones, via the Schmidt reaction, using trimethylsilylazide and trifluoroacetic acid. A series of tetrazoles {2,3-dihydro-2-phenyl-tetrazolo[1,5-d]-1,4-benzoxazepines} were also isolated as by-products of the Schmidt reaction. Flavanone oxime was synthesized for use in Beckmann reactions, and its molecular structure was determined by x-ray crystallography. Attempts to prepare 1,4-benzoxazepinone or its 1,5-analogue via Beckmann rearrangement of flavanone oxime, with polyphosphoric acid or phosphorus pentachloride catalysts, however, were unsuccessful. Several methods for introducing Δ²-unsaturation into the benzoxazepinone system were also examined. High resolution ¹H n.m.r., computer modelling, and molecular mechanics techniques were used to determine the conformations of the heterocycles of the benzoxazepinones and tetrazoles and results are compared with earlier studies in this field. Certain trends in the fragmentation patterns were observed in the low resolution mass spectra of the benzoxazepinones and tetrazoles, and high resolution mass spectrometric data were used to explore the major fragmentation patterns of these compounds.
  • Full Text:
  • Date Issued: 1990

A study of real-time operating systems for microcomputers

  • Authors: Wells, George Clifford
  • Date: 1990
  • Subjects: Operating systems (Computers) , Microcomputers
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4611 , http://hdl.handle.net/10962/d1004896 , Operating systems (Computers) , Microcomputers
  • Description: This thesis describes the evaluation of four operating systems for microcomputers. The emphasis of the study is on the suitability of the operating systems for use in real-time applications, such as process control. The evaluation was performed in two sections. The first section was a quantitative assessment of the performance of the real-time features of the operating system. This was performed using benchmarks. The criteria for the benchmarks and their design are discussed. The second section was a qualitative assessment of the suitability of the operating systems for the development and implementation of real-time systems. This was assessed through the implementation of a small simulation of a manufacturing process and its associated control system. The simulation was designed using the Ward and Mellor real-time design method which was extended to handle the special case of a real-time simulation. The operating systems which were selected for the study covered a spectrum from general purpose operating systems to small, specialised real-time operating systems. From the quantitative assessment it emerged that QNX (from Quantum Software Systems) had the best overall performance. Qualitatively, UNIX was found to offer the best system development environment, but it does not have the performance and the characteristics required for real-time applications. This suggests that versions of UNIX that are adapted for real-time applications are worth careful consideration for use both as development systems and implementation systems.
  • Full Text:
  • Date Issued: 1990

The geology and alteration-mineralisation of the Gamigab Tin Prospect, Damaraland, Namibia

  • Authors: Walraven, Felix Caspar
  • Date: 1990
  • Subjects: Mineralogy -- Namibia -- Damaraland , Geology -- Namibia -- Damaraland , Tin mines and mining -- Namibia -- Damaraland
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4956 , http://hdl.handle.net/10962/d1005568 , Mineralogy -- Namibia -- Damaraland , Geology -- Namibia -- Damaraland , Tin mines and mining -- Namibia -- Damaraland
  • Description: The stratigraphy at the Gamigab Sn prospect consists of two mainly schistose units separated by a thick marble unit which have been assigned to the Orusewa, the Karibib and the Kuiseb Formations respectively. Four phases of folding affected the lithologies with the south-south-west trending F2 folds defining the main structures in the region. The area underwent low grades of metamorphism. Temperatures were in the range 420° to 500°C and pressures less than 2 kbars. The effects of contact metamorphism are seen in the south-east and south-west. Regional metamorphism outlasted the deformation and contact metamorphism started late during deformation. Two Karoo-age intrusions penetrated the metasediments north of the mineralisation. One is an altered porphyry plug and the other is a weathered dolerite plug, the latter containing xenoliths of undeformed Karoo sediments. Cassiterite is hosted within east-west trending quartz veins that cross-cut previously altered schistose country rocks. The alteration types include sericitisation, tourmalinisation, carbonatisation and ferruginisation. Preliminary Rb/Sr dating on muscovite from the alteration zone suggests an age of 509 ± 11 Ma. Breccias of probable hydrothermal origin are spatially associated with the mineralisation. These hydraulic breccias occur in antiformal structures within the marble and developed in response to a sudden pressure release due to a build up of fluids at the contact between the schistose Orusewa and carbonate Karibib Formations.
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  • Date Issued: 1990

Mzeno

A pastoral theological examination of inner healing

Tankatara bushveld, Sunday's River, Port Elizabeth

Tankatara bushveld, Sunday's River, Port Elizabeth

Tankatara bushveld, Sunday's River, Port Elizabeth

Tankatara bushveld, Sunday's River, Port Elizabeth

Tankatara bushveld, Sunday's River, Port Elizabeth

Lady's Slippers Rock, Witteklip Mt., Port Elizabeth

Near right bank of the Swartkops River, Port Elizabeth

  • Authors: Vanderplank, Helen J
  • Date: 1990
  • Subjects: Swartkops River (South Africa)
  • Type: still image
  • Identifier: vital:13171 , http://hdl.handle.net/10962/d1016807
  • Description: Saltmarsh conditions and the bushy nature of the low dunes. The beach and the sea immediately behind the dunes in the picture.
  • Full Text: false
  • Date Issued: 1990

Aspects of the nutritional physiology and dietary requirements of juvenile and adult sharptooth catfish, Clarias Gariepinus (Pisces : clariidae)

  • Authors: Uys, Wynand
  • Date: 1990
  • Subjects: Clariidae Catfishes Catfishes -- Nutrition-requirements Clarias
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5225 , http://hdl.handle.net/10962/d1005068
  • Description: Past and current research on the biology and culture of the sharptooth catfish (Clarias gariepinus) has stimulated the development of its commercial production. At the inception of this project in 1985, it was decided that the development of an optimal dry feed was the most important step in developing a more complete culture technology for the species. The objectives of the project were, therefore, to investigate aspects of the nutritional physiology and dietary requirements of the species to provide the necessary information for the formulation of optimum economical feeds. A review of the natural feeding biology of the species provided valuable information with regard to its food preferences. From this information, and by estimating the nutritional composition of its preferred natural diet, it could be concluded that the animal requires a relatively high dietary protein content. This conclusion was substantiated by studies of the functional morphology of the digestive system (gross and fine structure). The characteristics of the digestive system and external anatomy were found to be typical of an opportunistic, omnivorous predator. The ontogenetic development of the digestive system is relatively fast, and enables the utilization of a variety of diets efficiently from an early stage. Since the ability of an animal to digest a given substance is predominantly dependent on the presence of appropriate enzymes the quantification and characterization of C. gariepinus digestive enzyme activities were investigated on an experimental basis. This work revealed that the animal has relatively high levels of digestive enzyme activities, and that its proteolytic enzyme activities correspond with those of other carnivorous fishes, while its starch digesting abilities correspond with those of specialized herbivores. Also, the high levels of lysozyme and alkaline phosphatase indicate an adaptation to detritivory, making this fish a truly opportunistic omnivore. Evidence was found to suggest that sharptooth catfish are able to re-absorb secreted digestive enzymes in the posterior section of its intestinal tract. It was shown that digestive enzyme activities were induced by food intake, and that no inherent rhythmicity in digestive activities seemed to occur. The development of digestive enzyme systems in the early life history of this animal was found to be also extremely rapid (complete within 10-16 days after hatching). It was also shown that artificial dry feed stimulates higher levels of digestive enzyme activities in larvae and juveniles than natural food. Although increased cellulase activity was found in larvae and juveniles that were fed on live zooplankton, the relative contribution of exogenous prey enzymes to protein digestion could not be ascertained. Specific nutritional requirements were investigated by means of feeding trials. The results of these trials confirmed the above indications regarding the dietary requirements of sharptooth catfish. It was concluded that for optimal growth and production performance, this animal requires a dietary protein content of 40-42%, a dietary lipid content of 10-12% and that diets should contain 14-16 kJ/g digestible energy. The optimum protein-to-energy ratio was found to be 26-29mg protein per kJ of digestible energy. Dietary requirements are evidently the same for juveniles and adults, except that younger fish require higher relative feeding levels. Finally, practical feed formulations were evaluated in terms of their economic feasibility. The results of these trials are presented along with recommendations on the formulation of commercial feeds for C. gariepinus. A computer program with which to implement least cost feed formulation by means of linear programming is provided.
  • Full Text:
  • Date Issued: 1990

Commission of Inquiry into Oukasie Violence

  • Authors: UDF
  • Date: 1990
  • Subjects: UDF
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/250651 , vital:52035
  • Description: In June 1990, the United Democratic Front [UDF] appointed Brian Cumin, National Director of Lawyers for Human Rights as Commissioner to investigate and report on the reasons for the violence in Oukasie Township, Brits, since February 1986. Brian Cumin was empowered to appoint additional Commissioners to assist him. David Bam and Mpho Molefe, both practising Attorneys in Pretoria were duly appointed as co-commissioners. As part of their report on the reasons for the violence in Oukasie, the Commissioners have taken the liberty of making recommendations to the United Democratic Front.
  • Full Text:
  • Date Issued: 1990

Wage negotiations: some practival information

  • Authors: Trade Union Research Project (TURP)
  • Date: 1990
  • Subjects: Wage distribution -- South Africa , Wages and labour productivity
  • Language: English
  • Type: book , text
  • Identifier: http://hdl.handle.net/10962/60029 , vital:27724
  • Description: The intention of this booklet is to assist unionists, shop stewards and organisers with preparation for wage negotiations. It raises ideas on how to deal with the common arguments that are used by management. This booklet is not a complete guide to wage negotiations. It concentrates mainly on economic factors which form only one part of wage negotiations. The handbook is divided into two sections. Section One deals with: Information about ownership, control and structure of South African companies; How to read and understand the information in a company’s annual report. Section Two deals with wage-related issues and it includes: Inflation; Subsistence levels and other surveys; Wages and wage policy. The booklet concludes with a checklist of information needed by wage negotiators and ends with a glossary of terms and a reference list.
  • Full Text:
  • Date Issued: 1990
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