Evaluation and optimization of selected methods of arsenic removal from industrial effluent
- Authors: Rubidge, Gletwyn Robert
- Date: 2004
- Subjects: Arsenic wastes , Water -- Purification -- Arsenic removal , Sewage -- Purification
- Language: English
- Type: Thesis , Doctoral , DTech (Chemistry)
- Identifier: vital:10981 , http://hdl.handle.net/10948/230 , Arsenic wastes , Water -- Purification -- Arsenic removal , Sewage -- Purification
- Description: This research was directed at reducing arsenic levels in the effluents generated at the Canelands facility that manufactures monosodium methyl arsenate. Two effluent streams containing arsenic have to be considered, a raw water stream that is treated on site and a brine stream that is disposed of by sea outfall. Removal of arsenate from aqueous media by coagulation was investigated and models were developed describing selected variables that influence the removal of the arsenate. Three coagulant systems were investigated, namely aluminium(III) coagulation, iron(III) coagulation and binary mixtures of aluminium(III) and iron(III). Researchers have studied individual aluminium (III) sulphate and iron(III) chloride coagulation. No detailed research and modelling had, however, been carried out on the use of binary mixtures of aluminium (III) sulphate and iron (III) chloride coagulation of aqueous arsenate, nor had individual aluminium(III) sulphate and iron(III) chloride coagulation of arsenate been modelled at relatively high arsenate concentrations. The models that were generated were validated statistically and experimentally. The variables investigated in the aluminium(III) model included initial arsenate concentration, pH, polymeric flocculent concentration, aluminium(III) concentration and settling time. The variables modelled in the iron(III) coagulation were initial arsenate concentration, pH, polymeric flocculent concentration, and iron(III) to arsenic mole ratio. The modelling of the binary coagulant system included initial arsenate concentration, pH, iron (III) concentration, aluminium(III) concentration, and flocculent concentration as variables. The most efficient arsenic removal by coagulation was iron(III), followed by the binary mixture of aluminium(III) and iron(III) and the weakest coagulant was aluminium(III) sulphate. Scale-up coagulations performed on real raw water samples at a 50 litre volume showed that iron(III) was the most efficient coagulant (on a molar basis) followed closely by the binary mixture, while aluminium(III) coagulation was considerably weaker. The residual arsenic levels of the iron(III) and the binary coagulation systems met the effluent discharge criteria, but the aluminium coagulation system did not. Leaching tests showed that the iron(III) sludge was the most stable followed by the sludge of the binary mixture and the aluminium(III)-based sludge leached arsenic most readily. Settling rate studies showed that the flocs of the iron(III) coagulations settled the fastest, followed by binary mixture flocs and the aluminium flocs settled the slowest. The flocs of the binary mixture had the lowest volume, followed by the iron(III) flocs, while the aluminium(III) flocs were the most voluminous. Based on current operations of the raw water treatment plant the aluminium(III)-based coagulation is the most cost efficient. Given a relative costing of 1.00 for the aluminium(III) coagulation, the iron(III) chloride-based coagulation would be 2.67 times more expensive and the equimolar binary mixed aluminium(III)/iron(III) system would be 1.84 times the cost of aluminium(III) coagulation.
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- Date Issued: 2004
Factors affecting the invasion of Pteronia incana (Blue bush) onto hillslopes in Ngqushwa (formerly Peddie) District, Eastern Cape
- Authors: Kakembo, Vincent
- Date: 2004
- Subjects: Shrubs -- South Africa -- Eastern Cape Slopes (Physical geography) -- South Africa -- Eastern Cape Biological invasions -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4833 , http://hdl.handle.net/10962/d1005508
- Description: The factors that influence the invasion of hillslopes by the shrub Pteronia incana in the communal rangelands of Ngqushwa (formerly Peddie) district were investigated. Mgwalana, one of the catchments in the district where encroachment by the species is widespread, was chosen. The study combined field observations with image analysis based on high resolution infrared imagery. The catchment was flown and high resolution infrared images (1mx1m) were taken using a Kodak DCS420 digital, colour-infrared camera. The images were analysed using Idrisi32 and Kilimanjaro GIS versions. The ability of different vegetation indices to separate P. incana from the other cover types was investigated. Field observations of the degree of P. incana invasion in relation to, inter alia, soil surface conditions, slope angle and visible forms of erosion were made. A Digital Elevation Model (DEM) of 20m spatial resolution was used to derive terrain parameters. The presence and absence of P. incana in relation to slope gradient and aspect were determined. The combined influence of the two terrain parameters and land use on the invasion was also investigated. The Topographic Wetness Index (WI), a component of the TOPMODEL was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. Soil moisture dependencies for P. incana and grass species as well as surrogates for runoff under the shrub and adjacent bare areas were determined in the field. A high level of classification accuracy confirmed the reliability of digital camera imagery for spatial analyses. Distinct spectral separability for the surface vegetation cover types was achieved by means of the Perpendicular Vegetation Index (PVI) as opposed to the ratio based vegetation indices (NDVI, SAVI and MSAVI). The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots. Blanket invasion of the former signified the high susceptibility of abandoned land to P. incana invasion. The combined influence of land use, slope gradient and aspect was also noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. Local topographic variations were identified as having a strong bearing on P. incana spatial distribution. The topographically driven WI confirmed this relationship, such that P. incana was associated with the low WI values of convexities. Differences in the moisture dependencies between P. incana and grass species were demonstrated by the greater rooting depth of the former. During field surveys, soil surface crusting was noted as inherent to P. incana patchiness. The coupling between local topography and soil surface crusting underpins soil moisture variability at hillslope and patch scales respectively. This in turn determines the competition between P. incana and grass species and the eventual replacement of the latter by the former. A close spatial correlation between fully established P. incana and severe forms of soil erosion was observed. Loss of patchiness and expansion of inter-patch bare areas promote runoff connectivity erosion. As most of the runoff becomes run out, hillslopes tend towards dysfunctional systems. Greater soil moisture storage after rainstorms under P. incana tussocks than the adjacent bare areas signifies the shrub’s water harvesting capabilities. The tussocks could thus serve as a starting-pointbuilding- block for the rehabilitation of dysfunctional hillslope systems.
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- Date Issued: 2004
Integrated anaerobic/aerobic bioprocess environments and the biodegradation of complex hydrocarbon wastes
- Authors: Ehlers, George A C
- Date: 2004
- Subjects: Hydrocarbons -- Biodegradation Sewage -- Purification -- Anaerobic treatment Water -- Purification -- Biological treatment Anaerobic bacteria Aerobic bacteria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4011 , http://hdl.handle.net/10962/d1004071
- Description: An investigation of the biodegradation of complex hydrocarbon wastes, with emphasis on chlorinated aromatic compounds, in an anaerobic/aerobic bioprocess environment was made. A reactor configuration was developed consisting of linked anaerobic and aerobic reactors which served as the model for a proposed bioremediation strategy targeting subterranean soil/sediment/aquifer chlorinated phenol-contaminated environments. Here oxygen is frequently limited and sulphate is readily available, as occurs especially in marine sediment and intertidal habitats. In the anaerobic system the successful transformation and mobilization of the model contaminant, 2,4,6-trichlorophenol, was shown to rely on reductive dechlorination by a sulphate-reducing dependent dechlororespiring co-culture. This was followed in the aerobic system by degradation of the pollutant and its metabolites, 2,4-dichlorophenol, 4-chlorophenol and phenol, by immobilized white-rot fungi.The strategy was initially investigated separately in laboratory bench- and intermediate scale reactors whereafter reactors were linked to simulate the integrated biodegradation strategy. The application of the fungal reactor to treat an actual waste stream by degrading complex mixtures of hydrocarbons in a waste oil recycling effluent was also investigated. The mineralization of phenol and 2,4,6-TCP by immobilized fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and TCP (800 and 85 mg.L⁻¹) concentrations were degraded by > 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.
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- Date Issued: 2004
Journeys of the learning soul: Plato to Descartes
- Authors: Hugo, Wayne
- Date: 2004
- Subjects: Education -- Philosophy Education -- History Education, Ancient Education, Greek
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1884 , http://hdl.handle.net/10962/d1005917
- Description: This thesis aims to build up a picture of what it has meant for us within the western canon to educate a human being through the depths and heights of existence. It uses narrative accounts of educational journeys from ancient, medieval and early modern sources to develop an integral picture of the spectrum of education along with the techniques and fore-structures needed to guide a student through the various stages and encounters. Key metaphors, journeys and relationships - Diotirna's ladder of beauty, Plato's cave, Philo's Abraham and Sarah, Origen's bride and Bridegroom, Plotinus' journey of the alone to the Alone, Augustine's Confessions, the tragic love of Abelard and Heloise, Dante's encounters in the infernal, purgatorial and paradisical realms of human experience, Shakespeare's great playing within the same realm, and Descartes' doubting genius provide a rich ensemble, each resonating with the next, opening out intellectual, affective, volitional, and imaginative paths through the full terrain of human existence. This multidimensional approach points towards a flexible and insightful pedagogics that works with the enormous variety and capacity of human learning rather than heavy-handedly insisting on one path, or, even worse, not recognizing and dealing with specific areas of human living that occur in the upper and lower reaches of our educational endeavours. Phenomenological, Hermeneutic and Integral methods suggested by Heidegger and Wilber amongst others were used to inform the process of research. The results of this thesis are not contained in its reconunendations but in the effects of its reading. It is itself a tool that embodies and encourages the principles of an educational tradition that has existed within the history of western learning, not seeking a return to ancient or medieval ways but to provide a backlight that assists current initiatives working with the full range of human potential.
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- Date Issued: 2004
Music and (post)colonialism : the dialectics of choral culture on a South African frontier
- Authors: Olwage, Grant
- Date: 2004
- Subjects: Choral music -- South Africa -- History Black people -- South Africa -- Music -- History and criticism Bokwe, John Knox, 1855-1922
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2679 , http://hdl.handle.net/10962/d1007717
- Description: This thesis explores the genesis of black choralism in late-nineteenth-century colonial South Africa, attending specifically to its dialectic with metropolitan Victorian choralism. In two introductory historiographic chapters I outline the political-narrative strategies by which both Victorian and black South African choralism have been elided from music histories. Part 1 gives an account of the "structures" within and through which choralism functioned as a practice of colonisation, as "internal colonialism" in Britain and evangelical colonialism in the eastern Cape Colony. In chapter 1 I suggest that the religious contexts within which choralism operated, including the music theoretical construction of the tonic sol-fa notation and method as "natural", and the "scientific" musicalisation of race, constituted conditions for the foreign mission's embrace of choralism. The second chapter explores further such affinities, tracing sol-fa choralism's institutional affiliations with nineteenth-century "reform" movements, and suggesting that sol-fa's practices worked in fulfilment of core reformist concerns such as "industry" and literacy. Throughout, the thesis explores how the categories of class and race functioned interchangeably in the colonial imagination. Chapter 3 charts this relationship in the terrain of music education; notations, for instance, which were classed in Britain, became racialised in colonial South Africa. In particular I show that black music education operated within colonial racial discourses. Chapter 4 is a reading of Victorian choralism as a "discipline", interpreting choral performance practice and choral music itself as disciplinary acts which complemented the political contexts in which choralism operated. Part 1, in short, explores how popular choralism operated within and as dominant politicking. In part 2 I turn to the black reception of Victorian choralism in composition and performance. The fifth chapter examines the compositional discourse of early black choral music, focussing on the work of John Knox Bokwe (1855-1922). Through a detailed account of several of Bokwe's works and their metropolitan sources, particularly late-nineteenth century gospel hymnody, I show that Bokwe's compositional practice enacted a politics that became anticolonial, and that early black choral music became "black" in its reception. I conclude that ethno/musicological claims that early black choral music contains "African" musical content conflate "race" and culture under a double imperative: in the names of a decolonising politics and a postcolonial epistemology in which hybridity as resistance is racialised. The final chapter explores how "the voice" was crucial to identity politics in the Victorian world, an object that was classed and racialised. Proceeding from the black reception of choral voice training, I attempt to outline the beginnings of a social history of the black choral voice, as well as analyse the sonic content of that voice through an approach I call a "phonetics of timbre".
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- Date Issued: 2004
On the mocvd growth of ZnO
- Authors: Pagni, Olivier Demeno
- Date: 2004
- Subjects: Zinc oxide thin films , Metal organic chemical vapor deposition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11075 , http://hdl.handle.net/10948/382 , Zinc oxide thin films , Metal organic chemical vapor deposition
- Description: Zinc oxide (ZnO) is a II-VI semiconductor material that offers tremendous potential as a light emitter in the blue-to-UV range. It has a wurtzite structure, and a direct band gap that can be tuned from 3.0 to 4.0 eV by alloying with Cd or Mg, respectively. In this work, ZnO thin films were grown by metalorganic chemical vapor deposition (MOCVD) on n-Si 2 ° off (100), amorphous glass, n-GaAs (100), and c-plane sapphire substrates. Diethyl zinc (DEZn) and tert-butanol (TBOH) were chosen as precursors. For the first time, Second Harmonic Generation Imaging was applied to the mapping of ZnO epilayers. The images obtained highlighted the polycrystalline character of the thin films, and provided insight as to the growth mode of ZnO on Si. The influence of substrate temperature on the structural properties of the epilayers was investigated by X-ray diffraction and optical microscopy. Grain sizes as high as 54 nm were measured. The optimum temperature range for this system proved to be 450 – 500 °C. The influence of the VI:II ratio during growth on the optical properties of the epilayers was studied by UV-vis-near IR spectroscopy. The lowest Urbach tail E0 parameter was measured for material grown at a VI:II ratio of 18:1. The films’ free electron concentration was shown to decrease by over two orders of magnitude, from 1019 to 1017 cm-3, as the VI:II ratio increased from 10 to 60:1. This decrease in carrier concentration with rising VI:II ratio was paralleled to the surge at 12 K of a photoluminescence (PL) emission band characteristic of p-type ZnO. The band gap energies extracted from room temperature transmission spectra ranged between 3.35 and 3.38 eV, in agreement with the value of 3.35 eV measured by room temperature PL. Moreover, variable temperature PL spectra were recorded between 12 and 298 K on ZnO grown on Si. The 12 K spectrum was dominated by a donor-bound exciton (D°X) at 3.36 eV, while the 298 K scan displayed strong free exciton emission (FX) at 3.29 eV. The width of the D°X band proved to be as narrow as 7 meV. The intensity ratio between the room temperature near-band edge emission and the defect-related green band was as high as 28:1, highlighting the optical quality of the layers deposited in this work. The electrical properties of the thin films were studied by Hall measurements (van der Pauw configuration), and a maximum room temperature mobility of 11 cm2/Vs was recorded. Furthermore, a palladium (Pd) Schottky barrier diode on ZnO was fabricated. The barrier height and ideality factor were calculated from current–voltage measurements to be 0.83 eV and 1.6, respectively. The capacitance–voltage curve of the diode yielded a carrier concentration in the depletion region of 8·1017 cm-3. This study has shown that the optical and electrical properties of ZnO depend strongly on the growth conditions employed. A suitable choice of growth parameters can yield high quality ZnO that may be used for various devices. Keywords: Hall, MOCVD, optical spectroscopy, photoluminescence, Schottky barrier diode, SH Imaging, X-ray diffraction, ZnO.
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- Date Issued: 2004
Price discovery, price behaviour, and efficiency of selected grain commodities traded on the agricultural products division of the JSE securities exchange
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
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- Date Issued: 2004
Purification and characterisation of 20S proteasome from ostrich skeletal muscle and its role in meat tenderisation
- Authors: Thomas, Adele René
- Date: 2004
- Subjects: Proteolytic enzymes , Ostrich products industry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:11081 , http://hdl.handle.net/10948/320 , Proteolytic enzymes , Ostrich products industry
- Description: The proteasome is renowned for its high molecular weight, multisubunit and mulicatalytic nature. One of its many suggested roles is the degradation of myofibrillar proteins, and therefore it has been proposed to play a role in the meat tenderisation process. The aim of this study was therefore to isolate, purify and characterise the 20S proteasome from ostrich skeletal muscle, with a view to ultimately investigating its role in the tenderisation process of ostrich meat. The 20S proteasome was successfully isolated and purified from ostrich skeletal muscle using Toyopearl Super Q-650S, Sephacryl S-300, hydroxylapatite and Mono Q chromatographies. The intact molecule showed a molecular weight of 725 K and a pI of 6.67. The subunits showed a molecular weight range of 22.2-33.5 K and a pI range of 3-9. 2D-PAGE revealed at least 14 polypeptides. The amino acid composition of the intact enzyme and of each of the eight subunits separating on SDSPAGE, as well as the N-terminal sequences of five of the eight subunits, were determined. The trypsinlike (Tr-L), chymotrypsin-like (ChT-L), peptidylglutamyl peptide hydrolase (PGPH) and caseinolytic activities showed pH optima of 11, 9, 7-8 and 10.3, and temperature optima of 40, 60, 70 and 60oC, respectively. The pH stability range for all four activities was 5-12. The ChT-L and PGPH activities showed thermostabilities up to 60oC, whereas the Tr-L and caseinolytic activities were stable up to 40o C. The enzyme showed complex kinetics. It was inhibited by the peptide aldehyde Z-LLL-CHO and cysteine protease inhibitors. Cations had negligible effects on the enzyme, excepting for Ca2+ and Mg2+. Of the detergents tested, SDS had the most potent stimulatory effect, particularly on the PGPH and caseinolytic activities. The fatty acid studies showed that unsaturation enhanced the ChT-L and the caseinolytic activities, while it completely suppressed the Tr-L activity. Heating at 60oC for 1-2 min stimulated the caseinolytic and PGPH activities. The studies on the role of ostrich skeletal muscle 20S proteasome in ostrich meat tenderisation suggested a definite but minor role of this enzyme, based on the fact that it remained active throughout the 12 days of storage of ostrich M. iliofibularis meat at 4oC and that it participated in myofibril degradation of post-mortem muscle, but to a small degree. These results support the proposal that the proteasome comes into play after the calpains have initiated degradation. However, there was a lack of improvement in tenderness values and minimal myofibrillar degradation over the 12-day storage period of the ostrich M. iliofibularis meat, leading to the conclusion that the tenderisation of this meat was incomplete after 12 days.
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- Date Issued: 2004
Rights-based restitution in South Africa : developmental land reform or relocation in reverse?
- Authors: Roodt, Monty
- Date: 2004
- Subjects: Restitution -- South Africa , Land reform -- South Africa , Right of property -- South Africa , Land settlement -- South Africa , Land tenure -- South Africa , South Africa -- Commission on Restitution of Land Rights
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3351 , http://hdl.handle.net/10962/d1007211 , Restitution -- South Africa , Land reform -- South Africa , Right of property -- South Africa , Land settlement -- South Africa , Land tenure -- South Africa , South Africa -- Commission on Restitution of Land Rights
- Description: The main question of this thesis is to what extent the rights-based and market-driven nature of the restitution program has given rise to a legalistic and bureaucratic process that negates both the demand-driven and the developmental aspects of restitution as land reform. I answer this question by showing that the choice of a Constitutional model with a Bill of Rights provides the background for a rights-based land reform program. This is especially true for the restitution sub-program, one of the three branches along with redistribution and tenure of the overall land reform program. I then consider the debate around the property clause, and how its inclusion provided the context for a market and rights-based approach to land reform as opposed to a supply-led administrative approach. Because the property clause as a First Generation right prevents expropriation of land without market-related compensation, a complex and legalistic land reform program falling within the ambit of Second Generation rights was formulated to address the gross imbalance in land ownership in South Africa. I argue that the contemporary origin of Second Generation human rights lies within the context of class and anti-globalisation struggles for democracy, and that they are something to be fought for and defended. I discuss the distinction between First, Second and Third Generation rights and identify four spheres within which the struggle for Second and Third Generation rights takes place within modern democratic states. These are the state, the representative public sphere, civil society and the private sphere. I then deal with the problem of trying to turn "paper rights" into realisable rights for the more disadvantaged sectors of society. I also look at what impedes their realisation. I argue that a number of strategies are necessary to ensure the delivery of Second and Third Generation rights. These are an adequate legislative framework, a good communication strategy, the development of institutional capacity to deliver, and if all else fails, access to conflict resolution mechanisms. I consider the major impediments to the realisation of Second and Third Generation rights to be the way in which they are defined in relation to First Generation rights, especially the property clause, the way in which access to rights-backed resources through formal institutions are mediated by the operation of informal institutions, and the dearth of administrative competence in South Africa. My point is that in order for Second and Third Generation rights to have practical benefit for the dispossessed and poor, extraordinary measures are needed. The Restitution arm of the land reform program provides in theory just such extraordinary measures, albeit for only a section of the population. I analyse the effectiveness of the Land Claims Court in assisting restitution claimants and the rural poor to realize their rights. I trace the slow and haphazard shift from a positivistic statutory interpretation (narrow, literal, legalistic) to a purposive interpretation (informed by the Constitutional spirit and social purpose of the legislation) by the Court. This is followed by an analysis of the restitution business process, which means tracing the path of the claim from lodgement to settlement. I set out the costly, complex and legalistic implementation and policy process in some detail. My argument is that in order for a rights-based approach to overcome the impediments outlined in Chapter 3, as well as the property clause in the Constitution, its architects designed a complex process that in the end proved counter-productive in terms of its original aims. The failure of the process to deliver led in 1998 the then Minister of Land Affairs, Derek Hannekom, to appoint a Ministerial Review to investigate the problems. Problems included: slowness of delivery, the crisis of unplannability, low levels of trust between implementers, and high levels of frustration. Two issues are analysed more fully, the rights-driven approach as opposed to the rights-based approach and the lack of claimant participation in taking control of the restitution process. I examine the relationship of the Restitution Commission to the Department of Land Affairs and to municipal land use planning processes. The emphasis on rights within the restitution program had the effect of distancing restitution, especially in the first few years of the programs' existence, from the rest of the land reform program, as well as from the local government process of formulating land development objectives (LDOs), and the Integrated Development Planning (lOP) process. I look at the Port Elizabeth Land and Community Restoration Association (Pelcra) as a case study as it embodies an approach that tries to move beyond a mere reclaiming of rights in land and attempts to implement a developmental approach. I conclude that the rights-based restitution program in spite of its many shortcomings has had some success. It has moved slowly from an overly legalistic judicial program to a more administrative but still bureaucratic process, that has delivered only 27 percent of its product as land reform, the rest going to monetary compensation mainly in urban areas. Thus it can be argued that restitution has been more successful as a program to promote reconciliation along the lines of the Truth and Reconciliation Commission, than as a land reform program, especially if one regards land reform as the restoration of rural land to the indigenous population. There have also been some successful attempts by the Commission, such as in the case of PELCRA, to integrate the processing of its claims with local government planning processes, but progress in this direction remains patchy.
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- Date Issued: 2004
Spirituality in the fiction of Henry Rider Haggard
- Authors: Senior, John
- Date: 2004
- Subjects: Haggard, H. Rider (Henry Rider), 1856-1925 -- Religion Haggard, H. Rider (Henry Rider), 1856-1925 -- Criticism and interpretation Religion in literature Spirituality in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2209 , http://hdl.handle.net/10962/d1002252
- Description: Neither an unquestioning support for British imperialism nor a personal pre-Jungian philosophy were the driving forces behind Rider Haggard’s beliefs or his literature. These two concerns were secondary to the author’s fascination with the supernatural, a theme prominent in his era, but less so in our own. A declining faith in European religion provided the dominant focal point in Haggard’s work. Although there are important overtones of imperial concern and indeed points of Jungian significance in the texts, these are generally subservient to an intensive wide-ranging spiritual discourse. The place of Haggard’s work in history and its literary merit are thus misunderstood when his spiritualism is not taken into account. No analysis of the author’s work can be complete without first coming to terms with his spiritual ideas and then with their impact on other topics of significance to both the author and audiences of his day. The spiritual or religious aspect of his writing has been largely ignored because of its subtle nature and its relative unfashionability throughout most of the twentieth century in the critical and intellectual climate of the Western world. However, in the Victorian era, under the materialist impact of Darwin, Marx and industrialization, Europe's Christian God was pushed from centre stage, creating widespread spiritual hunger and anguish. In the resulting religious vacuum Haggard's overtures were of particular significance to his audience. In fact, when considered in terms of his immense contemporary popularity, the pervasive presence of spirituality throughout Haggard's works and in his personal writing gives some indication of the subject's enormous importance not only to the author, but to late Victorian society as a whole. In light of this Victorian significance, the spiritual element rises, by its constant presence and persistent foregrounding, to subvert not only the imperial and the Jungian, but even Haggard's overt adventure text by dealing directly with the underlying metaphysical crisis in Western society.
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- Date Issued: 2004
The concentration of ten metals in the tissues of shark species Squalus megalops and Mustelus mustelus (Chondrichthyes) occuring along the Southeastern coast of South Africa
- Authors: Erasmus, Christina Petronella
- Date: 2004
- Subjects: Sharks -- South Africa -- Effect of metals on. , Marine pollutio -- South Africa.
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11095 , http://hdl.handle.net/10948/d1019683
- Description: The southeastern coast of South Africa is deemed unpolluted and with the exception of a few localized areas, is believed to be pristine. This study aimed to (1) assess the concentration of metals in the water and sharks (Squalus megalops, Mustelus mustelus) from different sites along the southeastern coast, (2) determine the effects that metals have on each other and investigate the accumulation and storage of metals in different shark tissues, (3) determine the effects of length and sex on metal concentration and the presence of metallothioneins in the liver. Metal concentrations in water from seven sites along the southeastern coast revealed concentrations below the detection limit of the extraction method, except for iron at St. Francis Bay which was below the recommended levels as supplied by DWAF. Met al concentrations in S. megalops from the seven sites revealed significantly elevated levels in individuals from Algoa and St. Francis Bay when compared to the other 5 sites. This was observed for all metals except manganese, which had a higher concentration at Cape Agulhas. After comparing the metal levels in muscle tissue (S. megalops) with data from the Department of Health it was concluded that the sharks caught at Algoa and St. Francis Bay were unsuited for human consumption. Liver and vertebral tissues from both S. megalops and M. mustelus were deemed unsuited for human consumption but further research should be conducted especially on vertebral metal concentrations. Comparing the metal concentration in different tissue types of S. megalops and M. mustelus significant difference were observed and attributed to differences in the maturity (thus age) of the two species. Significant differences in the metal concentration of males and females for both the species were observed. A higher number of differences were however observed in M. mustelus than in S. megalops, most probably due to the differences in maturity. Length and weight vs. metal concentration regressions in the males and females of both species revealed more negative than positive trends. This was found to be in accordance with other studies from around the world. Using the life stages of S. megalops, significant differences in the average concentration of metals were observed between the life stages, with embryos usually having the highest concentration. The metal concentration series determined for S. megalops were similar to that which have been reported in the literature in that iron and zinc occupied the highest concentration positions while cadmium, copper and manganese occupied the last three. The spleen usually had the highest metal concentration except for aluminium in skin and arsenic in muscle tissue. Pearson correlation revealed significant negative correlations between cadmium and the mentioned metals suggesting that cadmium replaces essential metals such as manganese, iron and copper as. Negative correlations between essential metals were observed most probably due to the competition for binding positions on ligands. Positive correlations were observed between metals in sp ecific tissue types and may be indicative of synergistic effects, e.g. aluminium may result in the accumulation of other metals such as cadmium. Positive and negative correlations between a specific metal and different tissue types have also been observed and it appears that there are movement of metals between tissue types. Positive correlation for essential metals between yolk and other tissue have been observed, although no correlations for non-essential metals were observed. This could potentially indicate a mechanism that prevents the accumulation of nonessential metals in embryos. Though no metallothioneins were isolated form the liver, the presence of cadmium in other proteins indicate that that cadmium is substituted for essential metals, and as this may result in deleterious physiological effects, further studies should be conducted. In conclusion it can be said that although some of the results were expected there are still quite a few unanswered question and further studies should be conducted.
- Full Text:
- Date Issued: 2004
The concentration of ten metals in the tissues of shark species Squalus megalops and Mustelus mustelus (chondrichthyes) occuring along the Southeastern coast of South Africa
- Authors: Erasmus, Christina Petronella
- Date: 2004
- Subjects: Sharks -- South Africa -- Effect of metals on , Marine pollution -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11085 , http://hdl.handle.net/10948/328 , Sharks -- South Africa -- Effect of metals on , Marine pollution -- South Africa
- Description: The southeastern coast of South Africa is deemed unpolluted and with the exception of a few localized areas, is believed to be pristine. This study aimed to (1) assess the concentration of metals in the water and sharks (Squalus megalops, Mustelus mustelus) from different sites along the southeastern coast, (2) determine the effects that metals have on each other and investigate the accumulation and storage of metals in different shark tissues, (3) determine the effects of length and sex on metal concentration and the presence of metallothioneins in the liver. Metal concentrations in water from seven sites along the southeastern coast revealed concentrations below the detection limit of the extraction method, except for iron at St. Francis Bay which was below the recommended levels as supplied by DWAF. Met al concentrations in S. megalops from the seven sites revealed significantly elevated levels in individuals from Algoa and St. Francis Bay when compared to the other 5 sites. This was observed for all metals except manganese, which had a higher concentration at Cape Agulhas. After comparing the metal levels in muscle tissue (S. megalops) with data from the Department of Health it was concluded that the sharks caught at Algoa and St. Francis Bay were unsuited for human consumption. Liver and vertebral tissues from both S. megalops and M. mustelus were deemed unsuited for human consumption but further research should be conducted especially on vertebral metal concentrations. Comparing the metal concentration in different tissue types of S. megalops and M. mustelus significant difference were observed and attributed to differences in the maturity (thus age) of the two species. Significant differences in the metal concentration of males and females for both the species were observed. A higher number of differences were however observed in M. mustelus than in S. megalops, most probably due to the differences in maturity. Length and weight vs. metal concentration regressions in the males and females of both species revealed more negative than positive trends. This was found to be in accordance with other studies from around the world. Using the life stages of S. megalops, significant differences in the average concentration of metals were observed between the life stages, with embryos usually having the highest concentration. The metal concentration series determined for S. megalops were similar to that which have been reported in the literature in that iron and zinc occupied the highest concentration positions while cadmium, copper and manganese occupied the last three. The spleen usually had the highest metal concentration except for aluminium in skin and arsenic in muscle tissue. Pearson correlation revealed significant negative correlations between cadmium and the mentioned metals suggesting that cadmium replaces essential metals such as manganese, iron and copper as. Negative correlations between essential metals were observed most probably due to the competition for binding positions on ligands. Positive correlations were observed between metals in sp ecific tissue types and may be indicative of synergistic effects, e.g. aluminium may result in the accumulation of other metals such as cadmium. Positive and negative correlations between a specific metal and different tissue types have also been observed and it appears that there are movement of metals between tissue types. Positive correlation for essential metals between yolk and other tissue have been observed, although no correlations for non-essential metals were observed. This could potentially indicate a mechanism that prevents the accumulation of nonessential metals in embryos. Though no metallothioneins were isolated form the liver, the presence of cadmium in other proteins indicate that that cadmium is substituted for essential metals, and as this may result in deleterious physiological effects, further studies should be conducted. In conclusion it can be said that although some of the results were expected there are still quite a few unanswered question and further studies should be conducted.
- Full Text:
- Date Issued: 2004
The development of a human resource model that supports the establishment of an ethical organisational culture
- Authors: Mey, Michelle Ruth
- Date: 2004
- Subjects: Corporate culture , Business ethics , Personnel management
- Language: English
- Type: Thesis , Doctoral , DTech (Human Resource Management)
- Identifier: vital:10869 , http://hdl.handle.net/10948/218 , Corporate culture , Business ethics , Personnel management
- Description: Corruption and unethical management is a legitimate global economic concern as it can have a direct and substantial impact on the longevity and the economic success of an organisation, an industry and a country. As a result of individuals having more readily available access to information, much attention has been given to unethical behaviour and organisational ethical violations over the last decade. Recent events have indicated that business ethics is an organisational concern with mammoth implications for business. For example, Esterhuyse (1999, p. 27) reports that South Africa has lost astronomical amounts of money due to office or white-collar crime. Organisations’ attempts to become globally competitive will be hampered by the behaviour of employees who are unethical at work. Therefore, it is imperative that organisations implement measures to increase ethical awareness and behaviour in their employees. This research study deals with business ethics in the automotive cluster of the Eastern Cape Province and proposes a model that can assist an organisation in improving its ethical culture. The main question that this research study addressed was: To what extent do the strategies of human resource departments contribute to establishing and maintaining an ethical organisational culture? To answer the above question it was necessary to address the most universal characteristics of ethical organisations. To this end the role of the human resource department in attempting to develop and sustain an ethical organisational culture is discussed. Thereafter, various ethical models are outlined and evaluated. Lastly, the proposed ethical model for establishing an ethical organisational culture is presented. Based on the theoretical findings of the literature survey which outlined the characteristics of ethical organisations and the interventions required to improve the ethical functioning of an organisation, a questionnaire was developed and distributed to organisations within the automotive cluster in the Eastern Cape Province. The empirical results obtained from the survey indicated dominant consensus regarding the model (see Chapter Four). The main findings from this research are that 74.7 per cent of organisations that participated in the empirical study had implemented a code of ethics. However, the majority of these organisations had not implemented the identified critical and optional interventions (see to Chapter Four) required to operate as an ethical organisation. The study also revealed that 49.4 per cent of respondents believed that the human resource manager is responsible for organising and coordinating an ethical initiative within the organisation. Respondents in this study stated that the benefits of operating ethically are the improved financial position of the organisation (76.5 per cent), the enhanced morale of employees (95.3 per cent), positive stakeholder perception (93 per cent), better long-term strategic sustainability (94.3 per cent) and superior social responsibility (85.9 per cent).
- Full Text:
- Date Issued: 2004
The development of a self-disintegrating core-body for use in an art bronze-casting foundry which employs the ceramic-shell investment technique
- Authors: Lomax, Lawrence Talbot
- Date: 2004
- Subjects: Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8499 , http://hdl.handle.net/10948/219 , Sculpture -- Technique , Bronze founding , Precision casting , Shell molding (Founding)
- Description: The development of a disintegrating core-body for use in an art bronze foundry, which employs the ceramic shell investment process, begins with an investigation of four principal materials that will constitute the core formula. The specifications for the disintegration of the designed core-body formula fall within the parameters that are normally set and used in the ceramic shell art bronze casting process. The raison d’ être for the disintegrating formula is based on the premise that cement breaks down (spalling) after being subjected to heat above a certain temperature. It was shown that pure cement in the form of naked test bars 100 mm x 20 mm x 20 mm does indeed break down into separate pieces when fired to and above 9000C; where 9000C is the lowest recommended temperature required for sintering the ceramic shell investment mould. The addition of calcium carbonate to pure cement in the form of naked test bars, produced a more unified formula that did not break into separate pieces when fired to 9450C. However this combination of cement and calcium carbonate had a slow setting time of 12 hours and a shrinkage value of 2,3%, which were both above the parameters being sought for a quick-setting formula with a shrinkage value of below 1%. The combination of cement, plaster of paris and silica produced formulae that set within six hours and had shrinkage values of less than 1% but did not disintegrate within 72 hours. It was only after the addition of calcium carbonate to the these mixes that formulae resulted that set within six hours, had relatively low shrinkage values and showed signs of breaking up after 60 hours. It was further shown that by altering the ratios of cement, plaster of paris, calcium carbonate and silica, that the parameters for quick-setting formulae with shrinkage values of 1% and below, that also disintegrated within 55 hours, could be achieved. xvi It was also proved by subjecting these formulae to higher relative humidity conditions that the disintegrating times could be reduced and brought to below 48 hours. Selected formulae were then subjected to temperatures of between 9000C and 10000C. It was found that as the temperatures were increased so the disintegration times were reduced and were even further reduced under higher relative humidity conditions. It was found from the above experiments that the selected formula determined to be suitable in all respects as a disintegrating core-body was too difficult to remove from the hollow bronze cast when subjected to an actual bronze pour. Further experimentation using increased proportions of silica in the formula resulted in a final core-body that could be quickly and easily removed from its bronze cast as soon as the core-body had cooled to room temperature. The selected core-body formula (F21D) that was used in the final set of bronze casting procedures was found to function optimally when fired to a temperature of 9000C and could be quickly and easily removed from the bronze casts leaving a clean inner bronze surface, free from any remnants of the fired core. The document concludes by recording the delimitations and advantages of the final core-body formula F21D, as well as making recommendations based on these parameters for further study relating to disintegrating core-body formulations.
- Full Text:
- Date Issued: 2004
The doctrine of duress in the law of contract and unjustified enrichment in South Africa
- Authors: Glover, Graham Brian
- Date: 2004
- Subjects: Contracts -- South Africa , Duress (Law) -- South Africa , Remedies (Law) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3672 , http://hdl.handle.net/10962/d1003187 , Contracts -- South Africa , Duress (Law) -- South Africa , Remedies (Law) -- South Africa
- Description: This thesis analyses the doctrine of duress and its application in the law of contract and unjustified enrichment in South Africa. Following an initial examination of the historical development of the doctrine from its roots in Roman and Roman-Dutch law, the study focuses on the current legal position in the two areas of law under review, identifies the substantive and formal deficiencies in the current approach, and suggests, using comparative authorities, how the law might be developed. As far as the law of contract is concerned, after exposing the difficulties inherent in the current approach, and placing the doctrine in its proper context in the South African law of contract generally, it is argued that the duress doctrine finds its juridical basis in the principle of good faith. A more modern and coherent test for duress is then proposed: one that concentrates on the question whether an illegitimate threat was made, which induced a contract in that it left the other person no reasonable choice but to succumb to the proposal. Additionally, the need for South African contract law to recognise and deal with cases of economic duress is emphasised. The study then shifts to an examination of the position in situations where non-contractual performances have occurred under duress: cases that are decided in terms of the principles of the law of unjustified enrichment. The current position is reviewed, and it is shown that the approach to duress cases is substantially different to the approach that applies in contract. An attempt is made to reconcile this problem. From a structural perspective, the nature and application of the relevant enrichment action where a non-contractual performance is made under duress (the condictio indebiti) is also investigated, in the light of approaches to enrichment adopted in both Germany and England, in an attempt to make better sense of this enrichment action in the South African context. The study closes with an analysis of the various contractual, delictual and enrichment remedies that are available once a case of duress has been proved.
- Full Text:
- Date Issued: 2004
The ecology and control of small hive beetles (Aethina tumida Murray)
- Authors: Ellis, James Douglas
- Date: 2004
- Subjects: Bee culture , Bee culture -- United States , Nitidulidae , Beetles -- Ecology , Beetles -- Control
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5917 , http://hdl.handle.net/10962/d1016253
- Description: The small hive beetle (Aethina tumida Murray) is an endemic scavenger in colonies of honey bee (Apis mellifera L.) subspecies inhabiting sub-Saharan Africa. The beetle only occasionally damages host colonies in its native range and such damage is usually restricted to weakened/diseased colonies or is associated with after absconding events due to behavioral resistance mechanisms of its host. The beetle has recently been introduced into North America and Australia where populations of managed subspecies of European honey bees have proven highly susceptible to beetle depredation. Beetles are able to reproduce in large numbers in European colonies and their larvae weaken colonies by eating honey, pollen, and bee brood. Further, adult and larval defecation is thought to promote the fermentation of honey and large populations of beetles can cause European colonies to abscond, both resulting in additional colony damage. The economic losses attributed to the beetle since its introduction into the United States have been estimated in millions of US dollars. Although beetles feed on foodstuffs found within colonies, experiments in vitro show that they can also complete entire life cycles on fruit. Regardless, they reproduce best on diets of honey, pollen, and bee brood. After feeding, beetle larvae exit the colony and burrow into the ground where they pupate. Neither soil type nor density affects a beetle’s ability to successfully pupate. Instead, successful pupation appears to be closely tied to soil moisture. African subspecies of honey bees employ a complicated scheme of confinement (aggressive behavior toward and guarding of beetles) to limit beetle reproduction in a colony. Despite being confined away from food, adult beetles are able to solicit food and feed from the mouths of their honey bee guards. Remarkably, beetle-naïve European honey bees also confine beetles and this behavior is quantitatively similar to that in African bees. If confinement efforts fail, beetles access the combs where they feed and reproduce. Two modes of beetle oviposition in sealed bee brood have been identified. In the first mode, beetles bite holes in the cappings of cells and oviposit on the pupa contained within. In the second mode, beetles enter empty cells, bite a hole in the wall of the cell, and oviposit on the brood in the adjacent cell. Despite this, African bees detect and remove all of the infected brood (hygienic behavior). Similarly, European bees can detect and remove brood that has been oviposited on by beetles. Enhancing the removal rate of infected brood in European colonies through selective breeding may achieve genetic control of beetles. Additional avenues of control were tested for efficacy against beetles. Reducing colony entrances slowed beetle ingress but the efficacy of this method probably depends on other factors. Further, the mortality of beetle pupae was higher when contacting species of the fungus Aspergillus than when not, making biological control an option. Regardless, no control tested to date proved efficacious at the level needed by beekeepers so an integrated approach to controlling beetles remains preferred. The amalgamation of the data presented in this dissertation contributed to a discussion on the beetle’s ecological niche, ability to impact honey bee colonies in ways never considered, and the ability to predict the beetle’s spread and impact globally.
- Full Text:
- Date Issued: 2004
The effects of selected proline-based cyclic dipeptides on growth and induction of apoptosis in cancer cells
- Authors: Brauns, Seth Clint Aron
- Date: 2004
- Subjects: Cyclic peptides , Antineoplastic agents -- Testing , Apoptosis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11088 , http://hdl.handle.net/10948/396 , Cyclic peptides , Antineoplastic agents -- Testing , Apoptosis
- Description: An increasing number of cyclic dipeptides (CDPs) have been shown to exhibit important biological activity including antifungal, antibacterial, anticonvulsant and immunomodulatory activity. Furthermore, some CDP derivatives have been shown to exhibit antitumour activity in vitro and in vivo. Several proline-based CDPs that exhibit biological activity have been detected in various processed foods and beverages. In the present study, the potential of seven proline-based CDPs to inhibit cancer cell growth was investigated in HT-29 (colon), HeLa (cervical), MCF-7 (breast) and WHCO3 (oesophageal) cancer cell lines. The CDPs used in this study were cyclo(Phe-Pro), cyclo(Tyr-Pro), cyclo(Gly-Pro), cyclo(Pro- Pro), cyclo(His-Pro), cyclo(Leu-Pro) and cyclo(Thr-Pro). The sulforhodamine B (SRB) cell growth assay was used in an initial screening phase to investigate the effects of the CDPs in HT-29, HeLa and MCF-7 cells. After exposing the cells to 10mM of the respective CDPs for 48 hours, the SRB assay results showed that only cyclo(Phe-Pro) exhibited more than 50% growth inhibition (p<0.01) in the three cell lines. The other CDPs showed comparatively marginal growth-inhibitory effects, except for cyclo(Tyr-Pro), which exhibited a pronounced effect in MCF-7 cells compared to HT-29 and HeLa cells. The MTT assay was used to confirm the SRB assay results for cyclo(Phe-Pro) and cyclo(Tyr-Pro), extending the investigation to the use of the fourth cell line WHCO3 and using a longer exposure time of 72 hours. The MTT assay demonstrated a dosedependent (0.008-10 mM) growth inhibition by cyclo(Phe-Pro) with an IC50 value of 4.04 ± 1.15 mM for HT-29 cells. Cyclo(Phe-Pro) was subsequently used to investigate whether the growth-inhibitory effects of this CDP were related to the induction of apoptosis in HT-29 cells. Hoechst 33342 staining showed that 5mM cyclo(Phe-Pro) induced characteristic chromatin condensation and nuclear fragmentation in 18.3 ± 2.8% (p<0.01) of HT-29 cells after 72 hours. Furthermore, annexin V binding revealed that HT-29 cells treated with 5 mM cyclo(Phe-Pro) displayed phosphatidylserine externalization after 48 hours. In addition, it was shown that 10 mM cyclo(Phe-Pro) induced poly(ADP-ribose)polymerase PARP cleavage, one of the hallmark events of apoptosis. The use of the broad-range caspase inhibitor Z-VAD-FMK, showed that this PARP cleavage was caspase-dependent, which in turn was confirmed by demonstrating an increase in caspase-3 activity (p<0.01) in cyclo(Phe- Pro)-treated HT-29 cells. In conclusion, these findings demonstrate that cyclo(Phe-Pro) inhibited the growth of HT- 29, MCF-7, HeLa and WHCO3 cells, and induced apoptosis in HT-29 colon cancer cells, suggesting the potential antitumour activity of cyclo(Phe-Pro)-related CDPs.
- Full Text:
- Date Issued: 2004
The enzymology of enhanced hydrolysis within the biosulphidogenic recycling sludge bed reactor (RSBR)
- Authors: Enongene, Godlove Nkwelle
- Date: 2004
- Subjects: Hydrolysis , Sewage sludge , Sewage -- Purification -- Anaerobic treatment , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4132 , http://hdl.handle.net/10962/d1015744
- Description: The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
- Full Text:
- Date Issued: 2004
The geology of the Proterozoic Haveri Au-Cu deposit, Southern Finland
- Authors: Strauss, Toby Anthony Lavery
- Date: 2004
- Subjects: Geology, Stratigraphic -- Precambrian , Geology, Stratigraphic -- Proterozoic , Ore deposits -- Finland , Geology -- Finland
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5081 , http://hdl.handle.net/10962/d1015978
- Description: The Haveri Au-Cu deposit is located in southern Finland about 175 km north of Helsinki. It occurs on the northern edge of the continental island arc-type, volcano-sedimentary Tampere Schist Belt (TSB) within the Palaeoproterozoic Svecofennian Domain (2.0 – 1.75 Ga) of the Fennoscandian Shield. The 1.99 Ga Haveri Formation forms the base of the supracrustal stratigraphy consisting of metavolcanic pillow lavas and breccias passing upwards into intercalated metatuffs and metatuffites. There is a continuous gradation upwards from the predominantly volcaniclastic Haveri Formation into the overlying epiclastic meta-greywackes of the Osara Formation. The Haveri deposit is hosted in this contact zone. This supracrustal sequence has been intruded concordantly by quartz-feldspar porphyries. Approximately 1.89 Ga ago, high crustal heat flow led to the generation and emplacement of voluminous synkinematic, I-type, magnetite-series granitoids of the Central Finland Granitoid Complex (CFGC), resulting in coeval high-T/low-P metamorphism (hornfelsic textures), and D₁ deformation. During the crystallisation and cooling of the granitoids, a magmatic-dominated hydrothermal system caused extensive hydrothermal alteration and Cu-Au mineralisation through the late-D₁ to early-D₂ deformation. Initially, a pre-ore Na-Ca alteration phase caused albitisation of the host rock. This was closely followed by strong Ca-Fe alteration, responsible for widespread amphibolitisation and quartz veining and associated with abundant pyrrhotite, magnetite, chalcopyrite and gold mineralisation. More localised calcic-skarn alteration is also present as zoned garnetpyroxene- epidote skarn assemblages with associated pyrrhotite and minor sphalerite, centred on quartzcalcite± scapolite veinlets. Post-ore alteration includes an evolution to more K-rich alteration (biotitisation). Late D₂-retrograde chlorite began to replace the earlier high-T assemblage. Late emanations (post-D₂ and pre-D₃) from the cooling granitoids, under lower temperatures and oxidising conditions, are represented by carbonate-barite veins and epidote veinlets. Later, narrow dolerite dykes were emplaced followed by a weak D₃ deformation, resulting in shearing and structural reactivation along the carbonate-barite bands. This phase was accompanied by pyrite deposition. Both sulphides and oxides are common at Haveri, with ore types varying from massive sulphide and/or magnetite, to networks of veinlets and disseminations of oxides and/or sulphides. Cataclastites, consisting of deformed, brecciated bands of sulphide, with rounded and angular clasts of quartz vein material and altered host-rock are an economically important ore type. Ore minerals are principally pyrrhotite, magnetite and chalcopyrite with lesser amounts of pyrite, molybdenite and sphalerite. There is a general progression from early magnetite, through pyrrhotite to pyrite indicating increasing sulphidation with time. Gold is typically found as free gold within quartz veins and within intense zones of amphibolitisation. Considerable gold is also found in the cataclastite ore type either as invisible gold within the sulphides and/or as free gold within the breccia fragments. The unaltered amphibolites of the Haveri Formation can be classified as medium-K basalts of the tholeiitic trend. Trace and REE support an interpretation of formation in a back-arc basin setting. The unaltered porphyritic rocks are calc-alkaline dacites, and are interpreted, along with the granitoids as having an arc-type origin. This is consistent with the evolution from an initial back-arc basin, through a period of passive margin and/or fore-arc deposition represented by the Osara Formation greywackes and the basal stratigraphy of the TSB, prior to the onset of arc-related volcanic activity characteristic of the TSB and the Svecofennian proper. Using a combination of petrogenetic grids, mineral compositions (garnet-biotite and hornblendeplagioclase thermometers) and oxygen isotope thermometry, peak metamorphism can be constrained to a maximum of approximately 600 °C and 1.5 kbars pressure. Furthermore, the petrogenetic grids indicate that the REDOX conditions can be constrained at 600°C to log f(O₂) values of approximately - 21.0 to -26.0 and -14.5 to -17.5 for the metasedimentary rocks and mafic metavolcanic rocks respectively, thus indicating the presence of a significant REDOX boundary. Amphibole compositions from the Ca-Fe alteration phase (amphibolitisation) indicate iron enrichment with increasing alteration corresponding to higher temperatures of formation. Oxygen isotope studies combined with limited fluid inclusion studies indicate that the Ca-Fe alteration and associated quartz veins formed at high temperatures (530 – 610°C) from low CO₂, low- to moderately saline (<10 eq. wt% NaCl), magmatic-dominated fluids. Fluid inclusion decrepitation textures in the quartz veins suggest isobaric decompression. This is compatible with formation in high-T/low-P environments such as contact aureoles and island arcs. The calcic-skarn assemblage, combined with phase equilibria and sphalerite geothermometry, are indicative of formation at high temperatures (500 – 600 °C) from fluids with higher CO₂ contents and more saline compositions than those responsible for the Fe-Ca alteration. Limited fluid inclusion studies have identified hypersaline inclusions in secondary inclusion trails within quartz. The presence of calcite and scapolite also support formation from CO₂-rich saline fluids. It is suggested that the calcic-skarn alteration and the amphibolitisation evolved from the same fluids, and that P-T changes led to fluid unmixing resulting in two fluid types responsible for the observed alteration variations. Chlorite geothermometry on retrograde chlorite indicates temperatures of 309 – 368 °C. As chlorite represents the latest hydrothermal event, this can be taken as a lower temperature limit for hydrothermal alteration and mineralisation at Haveri.The gold mineralisation at Haveri is related primarily to the Ca-Fe alteration. Under such P-T-X conditions gold was transported as chloride complexes. Ore was localised by a combination of structural controls (shears and folds) and REDOX reactions along the boundary between the oxidised metavolcanics and the reduced metasediments. In addition, fluid unmixing caused an increase in pH, and thus further augmented the precipitation of Cu and Au. During the late D₂-event, temperatures fell below 400 °C, and fluids may have remobilised Au and Cu as bisulphide complexes into the shearcontrolled cataclastites and massive sulphides. The Haveri deposit has many similarities with ore deposit models that include orogenic lode-gold deposits, certain Au-skarn deposits and Fe-oxide Cu-Au deposits. However, many characteristics of the Haveri deposit, including tectonic setting, host lithologies, alteration types, proximity to I-type granitoids and P-T-X conditions of formation, compare favourably with other Early Proterozoic deposits within the TSB and Fennoscandia, as well as many of the deposits in the Cloncurry district of Australia. Consequently, the Haveri deposit can be seen to represent a high-T, Ca-rich member of the recently recognised Fe-oxide Cu-Au group of deposits.
- Full Text:
- Date Issued: 2004
The reproductive biology and artificial breeding of ningu Labeo victorianus (Pisces: Cyprinidae)
- Authors: Rutaisire, Justus
- Date: 2004
- Subjects: Fishes -- Victoria, Lake , Cyprinidae -- Reproduction , Labeo -- Reproduction , Labeo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5317 , http://hdl.handle.net/10962/d1005162
- Description: Lake Victoria, the largest tropical lake, has faced an unprecedented assault on its ecosystem through a variety of anthropomorphic causes that include the introduction of Nile perch Lates niloticus and over-fishing. As a result there have been species extinctions and declining fish population trends. This thesis explores options for reversing these declining population trends and the restoration of collapsed fisheries based on indigenous non-cichlid species. A candidate species was chosen - the cyprinid fish Labeo victorianus. This thesis studied various aspects of L. victorianus' reproductive biology in two geographically distant populations. These included general reproductive patterns in relation to proximate environmental conditions, gonadal development and recrudescence, sex development, characterisation of genetic and morphological diversity, and induced spawning. Fish from both populations were found to be potamodrometic, and highly fecund, iteroparous spawners. L. victorianus was also shown to be an undifferentiated gonochorist, where all individuals pass through an intersexual juvenile stage prior to differentiation, and maturation to either sex. Sexual maturity was attained at a significantly larger size within the Kagera River than that of Sio River fish – possibly as a response to genotypic and/or phenotypic differences. Spawning seemed to be synchronised with rainfall in Kagera River - a pattern that was not strictly adhered to with the Sio River. Thorough microscopic investigation of recrudescence patterns indicated there was uninterrupted spawning in fish from the Kagera River followed by Type I oocyte atresia. In contrast, there was a 90% spawning failure, as characterised by Type II oocyte atresia, within the Sio River population. Aspects of spermatogenesis and sperm ultrastructure using light- and ultramicrotomic methods are described. Although the populations had varying reproductive biology parameters and were morphologically distinct, they remained undifferentiated at the mitochondrial level. Both populations were characterised by low nucleotide diversity – a feature attributed to a bottleneck event. The option of captive breeding was explored by conducting induced spawning experiments. Success was only achieved with a decapeptide Gonadotropic Releasing Hormone ([D-Arg⁶, Pro⁹-NEt])-sGnRH) in combination with a water-soluble dopamine receptor antagonist metoclopramide. This thesis stresses the importance of a research-oriented approach in the conservation of Lake Victoria's indigenous fish resources. It was concluded that information needed for the development of management policies can be generated within a reasonably short time period, of approximately three years, with modest levels of funding support.
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- Date Issued: 2004