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Regolith mapping and gold geochemical anomalies in the Siguiri Gold Mine of AngloGold Ashanti, Guinea, West Africa

  • Authors: Bah, Boubacar
  • Date: 2015
  • Subjects: AngloGold Ashanti Ltd. , Regolith -- Guinea -- Siguiri (Region) , Gold mines and mining -- Guinea -- Siguiri (Region) , Geochemical surveys -- Guinea -- Siguiri (Region) , Soil surveys -- Geochemical methods -- Guinea -- Siguiri (Region) , Kriging
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5090 , http://hdl.handle.net/10962/d1019878
  • Description: Gold exploration in the laterite terrains of the Siguiri basin (Guinea-West Africa) is discussed in this thesis. It seeks to propose and develop effective and reliable geochemical exploration techniques applied in such laterite terrains. The study is also intended to investigate and provide some geological clues as to why, in some target areas, the reconnaissance test drilling across the geochemical anomalies couldn’t intersect economic gold mineralisation. Targets were generated based on soil geochemical results, some of which were drilled without delivering economic discoveries even on areas with strong and consistent geochemical signatures. To find the failure and define the appropriate methods to be used is the core of the thesis. More importantly, the geological observation is aimed at sourcing and establishing the nature and validity of geochemical anomalies within the license area and their relationship with the underlying lithologies and structural networks. The geological field work conducted during this study is mostly based on regolith and surface geological mapping. The thick laterite cover, deep weathering, bedrock geology, gold geochemistry (the gold geochemical anomalous results are defined according to historical data before 2007), soil formations and variations in climate conditions are emphasized to illustrate the importance of mineral element mobility and dispersion in the weathering profiles. The knowledge and experience in regolith geochemistry and regolith mapping provide the advantage to exploration geologists. The depletion of ore resources and reserves in Siguiri and the continuous decline of the gold price in comparison to the complexity of exploring for gold are demanding more scientific-related thoughts and techniques to be integrated in the available geological, geochemical and geophysical information so as to reduce costs. The integration of good exploration strategy and technique may result in the possibility of making viable discoveries in this highly competitive geological environment where the mineral resources become depleted every day.
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  • Date Issued: 2015

Polyunsaturated fatty acid metabolism and effects on colon cancer cell biology in vitro.

  • Authors: Bulcao, Candice
  • Date: 2013
  • Subjects: Unsaturated fatty acids , Unsaturated fatty acids in human nutrition , Colon (Anatomy)-- Cancer , Cancer -- Nutritional aspects
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4137 , http://hdl.handle.net/10962/d1016128
  • Description: Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.
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  • Date Issued: 2013

Application of the Baylis-Hillman methodology in the construction of novel heterocyclic derivatives

  • Authors: Nyoni, Dubekile
  • Date: 2008
  • Subjects: Heterocyclic compounds -- Derivatives
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4402 , http://hdl.handle.net/10962/d1006704
  • Description: Baylis-Hillman reactions of 2,2’-dithiodibenzaldehyde with the acyclic alkenes, methyl vinyl ketone (MVK) and methyl acrylate have afforded the thiochromene derivatives in moderate yields, and this approach has been extended to the use of the cyclic alkenes, 2-cyclohexenone and 2-cyclopentenone to afford the tricyclic analogues. In all cases, reduction of the disulphide link and intramolecular cyclisation occurred in situ, and a preliminary kinetic study of this reaction using the acyclic substrates MVK and methyl acrylate was undertaken with the aim of elucidating the mechanism involved. The results obtained showed that the consumption of both 2,2’-dithiodibenzaldehyde and MVK and/or methyl acrylate followed 1st-order kinetics during the initial stages of the reaction, but then deviated from 1st-order linearity. The reaction with methyl acrylate was much slower than with MVK, and the kinetic data indicates the mechanism to be more complex than anticipated. Conjugate addition reactions of methyl acrylate-derived 2-nitrobenzaldehyde Baylis-Hillman adducts with the amines, piperidine and benzylamine, afforded a range of conjugate addition products as diastereomeric mixtures in excellent yield (80-100%). Catalytic hydrogenation of the conjugate addition products using a Pd-C catalyst in ethanol, has afforded the corresponding, novel 3-amino-2-quinolone derivatives in lower yield (22-37%).The application of [superscript 13]C NMR prediction programmes to selected compounds synthesized in this study has revealed reasonable correlations between the experimental and predicted values.
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  • Date Issued: 2008

Larval fish dynamics in the shallow nearshore of Eastern Algoa Bay with particular emphasis on the effects of currents and swimming abilities on dispersal

  • Authors: Pattrick, Paula
  • Date: 2008
  • Subjects: Fishes -- Larvae -- Eastern Cape -- Algoa Bay , Marine parks and reserves -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Ecology -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Dispersal -- Eastern Cape -- Algoa Bay , Fishes -- Development -- Eastern Cape -- Algoa Bay
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5294 , http://hdl.handle.net/10962/d1005139 , Fishes -- Larvae -- Eastern Cape -- Algoa Bay , Marine parks and reserves -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Ecology -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Dispersal -- Eastern Cape -- Algoa Bay , Fishes -- Development -- Eastern Cape -- Algoa Bay
  • Description: The larval fish assemblage in the shallow, nearshore region of a proposed marine protected area (MPA) in eastern Algoa Bay, temperate South Africa was investigated. Current velocities and direction and the swimming abilities of late-stage larvae were further assessed to determine potential larval movement to and from the MPA. In total, 6045 larval fishes were collected along two depth contours (~5m and ~15m) in the shallow nearshore of eastern Algoa Bay using stepped-oblique bongo net tows, twice per season for two years (March 2005 – January 2007). These larvae represented 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly between seasons peaking in spring with a mean of 64 larvae/100m3. Preflexion stage larvae dominated catches (75%). All developmental stages of Diplodus capensis, Engraulis capensis, Heteromycteris capensis, Sardinops sagax and Pomadasys species were found in the study area. It appears that these species use the shallow nearshore as a nursery area. Analysis of 12 months (May 2006 – May 2007) data from a bottom-moored Acoustic Doppler Current Profiler within the study area showed that offshore south eastward (39%) and onshore north westward currents (33%) dominated. The south westward current (15%) and north eastward current (12%) occurred less frequently. Current velocity decreased with depth in the nearshore, with a mean velocity of ~29 cms⁻¹ recorded at a depth of 4 m and a mean velocity of ~11 cms⁻¹ recorded at a depth of 14 m. Understanding the dispersal and movement of marine fish larvae in coastal habitats requires knowledge of active swimming abilities. The critical speed and endurance swimming of late stage larvae of two common inshore species occurring in the study area, Diplodus capensis and Sarpa salpa (Family Sparidae), were measured in a laboratory swimming chamber. The mean U-crit value for D. capensis (18.6 cms⁻¹) was similar to that of S. salpa (18.0 cms⁻¹), whereas mean endurance (km swum) was greater in S. salpa (8.4 km) than D. capensis (5.9 km). These swimming abilities exceed the average current velocities observed in the shallow nearshore providing larvae with the ability to greatly alter their passive dispersal trajectories and ultimately influence their distribution in the nearshore.
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  • Date Issued: 2008

Extending the reach of personal area networks by transporting Bluetooth communications over IP networks

  • Authors: Mackie, David Sean
  • Date: 2007 , 2007-03-29
  • Subjects: Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4637 , http://hdl.handle.net/10962/d1006551 , Bluetooth technology , Communication -- Technological innovations , Communication -- Network analysis , TCP/IP (Computer network protocol) , Computer networks , Computer network protocols , Wireless communication systems
  • Description: This thesis presents an investigation of how to extend the reach of a Bluetooth personal area network by introducing the concept of Bluetooth Hotspots. Currently two Bluetooth devices cannot communicate with each other unless they are within radio range, since Bluetooth is designed as a cable-replacement technology for wireless communications over short ranges. An investigation was done into the feasibility of creating Bluetooth hotspots that allow distant Bluetooth devices to communicate with each other by transporting their communications between these hotspots via an alternative network infrastructure such as an IP network. Two approaches were investigated, masquerading of remote devices by the local hotspot to allow seamless communications and proxying services on remote devices by providing them on a local hotspot using a distributed service discovery database. The latter approach was used to develop applications capable of transporting Bluetooth’s RFCOMM and L2CAP protocols. Quantitative tests were performed to establish the throughput performance and latency of these transport applications. Furthermore, a number of selected Bluetooth services were tested which lead us to conclude that most data-based protocols can be transported by the system.
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  • Date Issued: 2007

Exploring job satisfaction amongst government social workers in East London

  • Authors: Sela, Michelle
  • Date: 2001
  • Subjects: Social workers -- Supervision of , Social workers -- Professional ethics , Social workers -- South Africa -- Eastern Cape -- Attitudes , Social service -- Vocational guidance
  • Language: English
  • Type: Thesis , Masters , MSocSc
  • Identifier: vital:705 , http://hdl.handle.net/10962/d1006499 , Social workers -- Supervision of , Social workers -- Professional ethics , Social workers -- South Africa -- Eastern Cape -- Attitudes , Social service -- Vocational guidance
  • Description: During this research an attempt was made to gain an understanding of job satisfaction amongst government social workers. To achieve this, twenty social workers employed at the Department of Welfare in East London and Mdantsane were interviewed. South African literature on this topic is limited and it is believed that this study will present a valuable basis to pursue in further research. Literature that was consulted was found to be supportive of the theoretical notion that social work has long been recognised as being a stressful profession and that the nature of social work practice itself can be potentially stressful. The study found that there are many stressors and dissatisfactions which government social workers are currently experiencing. Some of the social workers have indicated a desire to leave the profession as a result of the dissatisfactions. The study findings suggest a need for combining oganisational with individual oriented initiatives to decrease the many stressors the social workers are experiencing. The thesis ends with recommendations of various strategies for addressing the concerns of the social workers in order to increase their job satisfaction
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  • Date Issued: 2001

A survey of the development of pitch perception theories, their application to bell sounds and an investigation of perceived differences between ringing and chiming bells

  • Authors: Botha, Alison
  • Date: 1998
  • Subjects: Music -- Acoustics and physics , Musical pitch , Change ringing , Chimes , Bells
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:2631 , http://hdl.handle.net/10962/d1002296 , Music -- Acoustics and physics , Musical pitch , Change ringing , Chimes , Bells
  • Description: A brief overview of the workings of the human auditory system is followed by a review of literature concerning both the theories and experimental investigations of human pitch perception. The application of these theories to the inharmonic complex tones produced by bells is discussed, and further experiments using bell sounds are reviewed. A methodology for psychoacoustic experiments with specific reference to those investigating pitch perception of inharmonic complex tones is presented. This methodology is then implemented in an experimental investigation of pitch perception of ringing and chiming bell sounds. A pitch matching experiment using ringing and chiming sounds from four bells aimed to determine perceived pitch differences between ringing and chiming bells. This experiment was inconclusive because insufficient data was collected. Known experimental results, such as the inability of non-musicians to match the pitches of sounds with different timbres were confirmed. Spectral analyses of the stimuli were performed. The presentation of stimuli at a low level of sensation is questioned, as this might have prevented pseudo high frequency noise resulting from stronger upper partials in the ringing sound from being audible, and hence the pitch differences between ringing and chiming bells would not be observed.
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  • Date Issued: 1998

A review of sediment-hosted gold deposits of the world with special emphasis on recent discoveries outside the U.S.A

  • Authors: Daglioglu, Yasar Mehmet
  • Date: 1996
  • Subjects: Gold ores , Sedimentation and deposition
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4997 , http://hdl.handle.net/10962/d1005609 , Gold ores , Sedimentation and deposition
  • Description: Most of the Great Basin sediment-hosted gold deposits are located along well defined, northwest-striking trends. Trends coincide with faults, intrusive rocks and magnetic anomalies. Sedimentary host rocks are siltstone, sandstone, conglomerate, argillic, interbedded chert and shales. Silty bedded silty dolomites, limestone and carbonaceous shales are the most favourable hosts. High, and locally, low-angle faults are very important structural features related to the formation of the ore bodies. High-angle faults are conduits of hydrothermal fluids which react, shatter and prepare the favourable host rock. Decalcification, silicification, and argillization are the most common hydrothermal alteration types. Jasperoid (intense silica replacement) is a significant characteristic; not all of these deposits are gold-bearing. Most deposits contain both oxidized and unoxidized ore. Fine grained disseminated pyrite, arsenian pyrite, and carbonaceous material are the most common hosts for gold in many deposits. These deposits are also characterized by high Au/Ag ratios, notable absence of base metal and geochemical associations of Au, As, Sb, Hg, Ba and TI. Recently numerous sediment-hosted gold deposits have been recognized in different regions of the world. They vary in their size, grades, textwe, host rock lithology, degrees of structural control and chemical characteristics. However, they have many common features which are very similar to the general characteristics of sediment-hosted gold deposits in the Great Basin, U.S.A. Besides these similarities, several unusual features are recorded in some newly discovered deposits elsewhere, such as predominant fault controlled paleokarst related mineralization and the lack of two very common trace elements (Hg, TI) in Lobongan/Alason, Indonesia; and Early Proterozoic age metamorphosed host rocks and lack of Sb in Maoling, China. The discovery of the deep ores in the Post-Betze and Rabbit Canyon, Nevada, proposed sediment-hosted Au emplacement at deeper level (4 ± 2 km; Kuehn & Rose, 1995) combined with a lack of field evidence for paleowater table and paleosurface features has ruled out a shallow epithermal origin. Recent discoveries in other parts of the world throw important new light on the ongoing genetic problems. Intrusive rocks are present in nearly all sediment-hosted gold deposits. Numerous intrusion-centred districts worldwide are characterized by tWo or more different mineralization types and consequently by metal zoning. Sediment-hosted gold deposits are proposed as a distal part of intrusion-centred magmatic hydrothermal systems (Sillitoe &Bonham, 1990).
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  • Date Issued: 1996

Structural studies on the capsular antigens of Escherichia coli serotypes K102 and K47

  • Authors: De Bruin, Aletta Hester
  • Date: 1991
  • Subjects: Escherichia -- Research , Klebsiella -- Research , Enterobacteriaceae -- Research , Antigens -- Research
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3754 , http://hdl.handle.net/10962/d1003232 , Escherichia -- Research , Klebsiella -- Research , Enterobacteriaceae -- Research , Antigens -- Research
  • Description: The work presented in this thesis forms part of a continuing programme concerned with the structural determination of capsular polysaccharides of some Enterobacteriaceae. Since bacteria of this family are pathogenic to Man, work in this laboratory has focused on the structural elucidation of Klebsiella and, more recently, Escherichia coli ( E. coli) capsular polysaccharides ( K-antigens ). To date, some 74 K-antigens have been distinguished serologically within the genus E. coli and the structures of approximately 70% are known. In general, the K-antigens of the E. coli are characterized by a wide variety of constituent monosaccharides arranged in repeating units. In this thesis the structural elucidation of the capsular polysaccharides of E. coli serotypes 08: KI02: H- and 08: K47: H2 is presented. A variety of chemical techniques has been employed in the structural analysis, and are discussed. The thesis also includes extensive two-dimensional n.m.r. studies on the E. coli KI02 and K47 polysaccharides, as well as on a modified KI02 polymer produced after a lithium-ethylenediamine degradation of the native polysaccharide.
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  • Date Issued: 1991

Geological factors affecting the grade and tonnage of sandstone uranium deposits

  • Authors: Holliman, K A
  • Date: 1981 , 2013-03-19
  • Subjects: Uranium ores , Sandstone , Geology, Economic
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5009 , http://hdl.handle.net/10962/d1005914 , Uranium ores , Sandstone , Geology, Economic
  • Description: The largest known reserves of uranium are found in sandstone deposits, in the form of roll-front, peneconcordant and stacked types. Drilling on spacings of between 50 m and 5 m centres is the current method of attempting to delineate such ore bodies but because of the apparent random distribution of the mineralization there is a large degree of uncertainty in these predictions. Even on drilling grids of 3,5 m centres the uncertainty in predicting the distribution of stringer ore in roll front mineralization is still 100 per cent. (Sandefur & Grant 1980). Because of escalating costs it is becoming increasingly less economically feasible to delineate bodies of this nature in this manner and much more reliance will have to be placed on the geologist's interpretation of ore distribution when calculating ore reserves. The grade and tonnage of a sandstone uranium deposit can only be calculated with some degree of confidence if the processes forming the ore body are fully understood. The aim of this review is to examine the factors governing the formation and geometry of a sandstone body, the mobility and fixation of uranium and to establish criteria which will enable a more confident prediction to be made of the distribution of sand bodies and the distribution of the mineralization within them
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  • Date Issued: 1981

Atmospheric ionization by precipitated electrons

  • Authors: Wulff, Annemarie
  • Date: 1973 , 2013-10-31
  • Subjects: Ionization , Electrons
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5503 , http://hdl.handle.net/10962/d1007229 , Ionization , Electrons
  • Description: From Introduction: Precipitation of energetic particl es into the upper atmosphere is known to cause aurora at high latitudes. Sanae is situated in the vicinity of the South Atlantic Geomagnetic Anomaly (Gledhill and Van Rooyen (1963)) where the magnetic field intensity is very low and it is felt that this phenomenon may enhance the loss of particles from the trapping zone into the upper atmosphere. Previous work at Rhodes has shown that it is extremely likely that particle precipitation could be the cause of some ionospheric effects at Sanae. Gledhill and Torr (1966) found that a "disturbed" ionosphere at Sanae was linked with "high" fluxes of precipitated electrons in the area conjugate to Sanae. Later papers by Gledhill, Torr and Torr (1967), and Torr and Torr (1967a, 1968a) established that electrons are precipitated over a large part of the earth's surface and this phenomenon is probably responsible for an average of about 30% of F-layer disturbances. The frequency of precipitation and corresponding disturbances is most pronounced in the South Atlantic Geomagnetic Anomaly . , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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  • Date Issued: 1973

Land use in Ward One of the Stutterheim district

  • Authors: Kopke, Desmond
  • Date: 1962
  • Subjects: Land use -- South Africa -- Stutterheim , Rural development -- South Africa -- Eastern Cape , Stutterheim (South Africa) -- Geography , Stutterheim (South Africa) -- Social conditions , Stutterheim (South Africa) -- History
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4883 , http://hdl.handle.net/10962/d1013465
  • Description: The work began with the production by the author of a geological map of the area, since this essential task had not previously been undertaken. A detailed study of the settlement plan, containing both European and African smallholders, was then made. This proved a very fruitful field of study, because within the area the settlement plan is undergoing dramatic changes which are having an effect on the land use pattern within the area. This study was concerned mainly with the production of a detailed land use map and a quantitative analysis of the land use distributions revealed by this map. The classification used fer the categories on the land use map closely resembles one used in the land use map of 'The Border Region' produced by the Border Regional Survey (1957/8) which was in turn based on the World Land Use Map classification. Accompanying this text are seven maps produced by the author, three of the land settlement plan (1: 50,000), one each of the geology (1: 50,000) and rainfall (1:125,000) and two of the land use (l: 50,000 and 1: 125,000) in the area. The field sheets (1: 18,000) which show the land use of the area in great detail, are to be found in the library of the Geography Departmont, Rhodes University in atlas form.
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  • Date Issued: 1962
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