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Growth and fruit production of Sclerocarya birrea in the South African lowveld

  • Authors: Shackleton, Charlie M
  • Date: 2002
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181618 , vital:43752 , xlink:href="https://doi.org/10.1023/A:1020579213024"
  • Description: Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro. is a common species throughout the semiarid, deciduous savannas of much of sub-Saharan Africa. It is a favoured species and is frequently maintained in homestead plots and arable fields in an agroforestry situation. Although the abundance and popularity of this species has led to several initiatives to commercialise a number of marula products, the sustainability of the resource base with respect to fruit production has not been considered. This paper reports on a field experiment that monitored growth rates and fruit production of a sample of adult trees from several wild populations. Mean fruit production was 36.8 kg per tree in the first year, and negligible in the second. This was considerably less than previous estimates, which were based largely on small samples or anecdotal reports. The maximum recorded yield was 416.6 kg per tree. Fruit production was positively related to the size of the tree. Growth rates of adult trees were slow. There was a strong positive relationship between mean annual diameter increment and stem diameter. The slow growth rates and low fruit yields indicate that more attention is required regarding the sustainability of there source and its ability to provide sufficient fruit for the growing subsistence and commercial demand at both local and national scales.
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  • Date Issued: 2002

The evaluation of waste minimization/waste treatment strategies for a commercial production process of 4-methyl-3-thiosemicarbazide

  • Authors: Bennen, Wilroy
  • Date: 2002
  • Subjects: Hazardous wastes , Hazardous substances -- Analysis
  • Language: English
  • Type: Thesis , Masters , MTech (Chemistry)
  • Identifier: vital:10951 , http://hdl.handle.net/10948/97 , Hazardous wastes , Hazardous substances -- Analysis
  • Description: Chemical synthesis is closely related to waste minimization. There is no chemical process that does not produce waste. The methods used by industry to deal with this waste is a major environmental concern. This thesis describes the laboratory scale waste minimization and waste treatment strategies for the commercial production process of 4-methyl-3-thiosemicarbazide (MTSC). The production process of 4-methyl-3-thiosemicarbazide was investigated with the aim of increasing the isolated yield of MTSC and at the same time decrease the amount and toxicity of effluent obtained. During this study, parameters were investigated such as the use of excess DIPEA and the temperature of the reaction. Preliminary studies clearly showed that both factors have a significant influence on the final yield of the product. The next part of the investigation was to optimize the two parameters influencing the isolated yield of the MTSC. For this investigation, a multi factorial design was used to determine the optimum conditions in the MTSC yield response. From the results obtained, it was clear that the excess of DIPEA and the temperature of the reaction both need to be high to obtain high yields. These theoretical results were confirmed by results obtained practically, where yields of up 82 % were obtained, but it became clear that even higher yields could be obtained since chromatographic results showed yeilds as high as 90 %. The mass balance of the MTSC synthesis showed a loss of approximately 30 grams per reaction. This loss may have an influence on the final yield. The effluent obtained during the synthesis of MTSC was investigated and a waste treatment protocol was established to reduce the high COD value of the MTSC effluent. The protocol consists of two steps used for the clean up of the effluent. The first being a cooling step; the effluent was cooled at 0oC to induce precipitation of a solid, consisting mostly of MTSC. The second step is a high pressure wet oxidation of the effluent with oxygen in a high pressure reactor. The remaining compounds in the effluent were oxidized, resulting in another precipitate, consisting mostly of sulphur. After the oxidation the COD value of the effluent was decreased by 98 % to a value of 0.4 %. The MTSC present in the precipitate obtained after cooling could be isolated and purified, to add to the yield of the synthesis. The sulphur obtained during the oxidation could also be isolated and reused, or sold to prevent it from contaminating the environment.
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  • Date Issued: 2002

An investigation of the management and leadership experiences of female school principals in the Ondangwa education regions

  • Authors: Udjombala, Maria
  • Date: 2002
  • Subjects: Women school principals -- Namibia -- Ondangwa Educational leadership -- Namibia -- Ondangwa
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1653 , http://hdl.handle.net/10962/d1003536
  • Description: This study explores practical school leadership and management, as enacted by women. The study, conducted in an interpretive paradigm, attempts to gain an understanding of women’s subjective experiences of school leadership and management. Two women principals from Ondangwa West Educational Region were interviewed. The two were selected through consultations with one of the senior inspectors in the region. Both had been principals for more than ten years and were seen by those who are concerned with their school to be successful. The study found that these women prefer a participative style of leadership and management, characterised by consultations with others, teamwork, collaborative decision-making and the use of power to empower others. They also strive for good human relationships because they believe that it fosters mutual respect, trust, openness and a good working atmosphere. All these human centred approaches are directed towards creating a school atmosphere that is conducive to teaching and learning and therefore result in effective schooling and quality educational outcomes. They do not experience gender discrimination in their work places. They have the full support of their supervisors. Though both are married with children, these dual roles do not prevent them from being successful in their professional work. In fact they have reached a stage where they feel confident as leaders and feel that they are acting as role models for fellow women principals and those aspiring to this position. The study concludes that the styles of leadership and management displayed by women are similar to those that are universally accepted as characteristics needed for effective school management and leadership. Though these leadership styles are traditionally associated with women, these characteristics are not gender specific. Therefore it will be in the best interest of schools, if school principals, both men and women, could borrow from these qualities in order to change schools from authoritarian to more democratic institutions.
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  • Date Issued: 2002

Intelligent gripper design and application for automated part recognition and gripping

  • Authors: Wang, Jianqiang
  • Date: 2002
  • Subjects: Automatic control , Robots, Industrial , Robotics
  • Language: English
  • Type: Thesis , Doctoral , DTech (Engineering)
  • Identifier: vital:10816 , http://hdl.handle.net/10948/102 , Automatic control , Robots, Industrial , Robotics
  • Description: Intelligent gripping may be achieved through gripper design, automated part recognition, intelligent algorithm for control of the gripper, and on-line decision-making based on sensory data. A generic framework which integrates sensory data, part recognition, decision-making and gripper control to achieve intelligent gripping based on ABB industrial robot is constructed. The three-fingered gripper actuated by a linear servo actuator designed and developed in this project for precise speed and position control is capable of handling a large variety of objects. Generic algorithms for intelligent part recognition are developed. Edge vector representation is discussed. Object geometric features are extracted. Fuzzy logic is successfully utilized to enhance the intelligence of the system. The generic fuzzy logic algorithm, which may also find application in other fields, is presented. Model-based gripping planning algorithm which is capable of extracting object grasp features from its geometric features and reasoning out grasp model for objects with different geometry is proposed. Manipulator trajectory planning solves the problem of generating robot programs automatically. Object-oriented programming technique based on Visual C++ MFC is used to constitute the system software so as to ensure the compatibility, expandability and modular programming design. Hierarchical architecture for intelligent gripping is discussed, which partitions the robot’s functionalities into high-level (modeling, recognizing, planning and perception) layers, and low-level (sensing, interfacing and execute) layers. Individual system modules are integrated seamlessly to constitute the intelligent gripping system.
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  • Date Issued: 2002

Product development as part of a positioning strategy for the hunting industry in the Eastern Cape

  • Authors: Van Niekerk, Pieter du Preez
  • Date: 2002
  • Subjects: New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Doctoral , DTech
  • Identifier: vital:10894 , http://hdl.handle.net/10948/111 , New products -- Marketing , Hunting -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Venison -- Marketing , Meat industry and trade -- South Africa -- Eastern Cape
  • Description: In this study on product development and positioning in the hunting industry in the Eastern Cape, two conceptual frameworks were developed, based on a literature study. These positioning and product development concepts were tested against primary and secondary information gathered about the hunting industry. The game and hunting industries were in a strong growth phase at the time of this study. These industries are playing an increasingly important role in the economy of the Eastern Cape, and more and more agricultural land is utilised for game ranching. From the perspective of obtaining a competitive advantage in an increasingly competitive environment, it is therefore important for hunting providers to develop suitable products, and to position these products correctly. It is also important to investigate the characteristics of the game and hunting industries in the Eastern Cape and to get information about the characteristics of the market in which product development and positioning take place. Hunting is the most important form of game utilisation in the Eastern Cape, followed by cropping of game and live game sales. At the time of this study, the total value of the game utilised annually in the Eastern Cape was in excess of R168 million. Game utilisation seemed to be taking place on a sustainable basis, as the number of animals utilised annually was less than the annual production. Kudu and springbok provide the biggest total income, and, together with mountain reedbuck, are the most abundant species in the Eastern Cape. The main game-producing areas in the Eastern Cape coincide with the areas where extensive beef, sheep and goat farming are practised. The hunting products on offer from hunting providers, differ in certain ways. Aspects like price, type of hunting provided, game species available for hunting, terrain where hunting takes place, and various other aspects in connection with the hunt, differ from hunting provider to hunting provider. Characteristics of the hunting experience that hunters desire may be divided into core and variable elements. The core elements include: · the conditions pertaining to the hunt being spelt out clearly; · the maintenance of safety standards; · reasonable day fees; · the presence of game in sufficient numbers; and · other aspects generally desired by hunters. In the study it was found that the needs of hunters also differ regarding certain aspects of the hunting experience. These variable elements include price levels, type and availability of accommodation, and the role of the hunting provider. The core aspects that hunters desire are as a rule part of the product offering. From a product development perspective, the variable elements provide an opportunity to customise products to hunter needs. The inclusion or exclusion of variable elements from the product offering give rise to certain unique product features, and therefore provide the opportunity for product differentiation. After development, products are positioned firstly by selecting a market segment to focus on. Secondly, the needs of hunters in the target segment should be clearly identified, followed by the development of suitable products based on hunter needs, and taking into account the features of competitive offerings. Decisions should also be taken about the features to be included in the product offering to achieve product differentiation. After development of a suitable product, an image or brand should be chosen for the product, and this image should be effectively communicated to the market. A number of possible positioning options were identified for hunting providers. It was found that factors like the physical features of the ranch, available infrastructure, the market segment chosen, desires of the hunting providers, and the perception of the needs of hunters, eventually influence decisions about product development and positioning. The final decisions on positioning should take the core competencies of the hunting provider into account and should ensure that the hunting provider has the ability to fill the chosen position in the market.
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  • Date Issued: 2002

Heal my heart: stories of hurt and healing from group therapy

  • Authors: Knight, Zelda G
  • Date: 2002
  • Language: English
  • Type: Article
  • Identifier: vital:6263 , http://hdl.handle.net/10962/d1007881
  • Description: This paper records four stories that emerged from four group therapy members. These stories are stories of fundamentally broken hearts. I utilise this material to address two psychological phenomena in group therapy - self-disclosure and the corrective emotional experience. The overarching theoretical framework is the existential approach to group therapy, and the underlying theoretical assumptions of relational psychoanalysis applied to group therapy. In the context of the material I present several theoretical points. Some of the chief points are the notion of the "in-between-ness of healing" and the importance of two processes in healing - i) the process of telling the story (remembering) in such as way that it is relived both emotionally and physically, and ii) followed closely by a corrective emotional experience. The emphasis in this paper is that remembering and reliving in therapy is not enough and a corrective emotional experience is required. Broadening this perspective of the healing mechanism of a corrective emotional experience, a principle argument of this paper is that the therapeutic action in group therapy (as it can be in individual therapy) is not insight but a new relationship.
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  • Date Issued: 2002

Development of nickel-selective molecularly imprinted polymers

  • Authors: Tshikhudo, Tshinyadzo Robert
  • Date: 2002 , 2013-07-25
  • Subjects: Imprinted polymers , Imprinted polymers -- Synthesis , Molecular imprinting , Nickel , Nickel -- Metallurgy
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4292 , http://hdl.handle.net/10962/d1004449 , Imprinted polymers , Imprinted polymers -- Synthesis , Molecular imprinting , Nickel , Nickel -- Metallurgy
  • Description: A series of eight novel bidentate ligands, designed for use in the construction of nickel-selective molecularly imprinted polymers (MIP's), have been prepared. The synthetic pathway was established by retrosynthetic analysis of the target molecules to the readily available precursors, pyridine-2-carbaldehyde (or 6-methylpyridine-2-carbaldehyde) and ethyl bromoacetate. The ligands were designed to contain an allyl group for co-polymerisation and amine and pyridyl nitrogen donors, located to permit the formation of 5-membered nickel chelates. The eight novel ligands and their respective precursors were characterized by elemental (high-resolution MS) and spectroscopic (IR and ¹H and ¹³C NMR) analysis. High resolution electron-impact mass spectrometry has also been used, together with B/E linked scan data, to explore the fragmentation patterns of selected ligands. The various nickel(ll) complexes were analyzed using spectroscopic techniques and, in some cases, elemental analysis; computer modelling has also been used to explore conformational effects and complex stability. Numerous MIP's, containing nickel(II) complexes of the bidentate ligands, have been prepared, using ethylene glycol dimethylacrylate (EGDMA) as the cross-linker, azobis(isobutyronitrile) (AlBN) as the polymerization initiator and MeOH as the porogenic solvent. The template nickel(II) ions were leached out with conc. HCI, and the nickel(II) selectivity [in the presence of Fe(Ill)] of the nickel-imprinted polymers was examined by ICP-MS analysis. The ICP-MS data indicate that the MIP's examined exhibit extremely high selectivity for nickel over iron. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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  • Date Issued: 2002

South African memoirs in a decade of transition: Athol Fugard's Cousins (1994), J.M. Coetzee's Boyhood (1997), and Breyten Breytenbach's Dog Heart (1999)

  • Authors: Roux, Christine Ann
  • Date: 2002
  • Subjects: Autobiography , Fugard, Athol , Coetzee, J. M., 1940 , Breytenbach, Breyten
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2191 , http://hdl.handle.net/10962/d1002233 , Autobiography , Fugard, Athol , Coetzee, J. M., 1940 , Breytenbach, Breyten
  • Description: This thesis examines three South African memoirs using M. M. Bakhtin’s theories of the dialogical relationship in language and literature. By offering an alternative to a postmodern or multicultural interpretation of autobiographies, Bakhtin’s precepts, that define a dialogic, help to reframe a way of discussing memoirs and avoiding dead-ends previously arrived at by essayists in James Olney’s 1980 collection. Bakhtin’s ideas discussed here, which include the “once-occurrent moment”, “architectonic contraposition”, ”emotional-volitional tone”, “alibi”, “non-alibi”, and “centripetal” and “centrifugal” force, help to rebuild a discussion based on temporary and evolving self truth rather than fiction, the postmodern interpretation, or confession, the new-age secular spiritualism based on multicultural and politically correct standards. For this, each author’s memoir had to be examined separately and a conclusion was arrived at through inductive analysis. Rather than try to find similar characteristics, I focused on what made each memoir different and unique. Janet Varner Gunn’s Autobiography: Toward A Poetics of Experience (1982) refocused the debate over autobiography on process. The question, what steps did each author take toward writing about himself, led the discussion to an examination of the priorities each author exemplified. Beginning with Fugard who emphasized spatial, concrete, and sensory detail to help him contain his emotional life, the thesis moves on to an examination of Coetzee’s sense of justice. From the physical and intellectual world follows Breytenbach’s spiritual space-making. In each memoir, control of space is evident on different levels of experience. Articulating space inevitably leads to a discussion of boundaries. Here, Charles Taylor’s emphasis on the modern self’s need to articulate a horizon or a framework is helpful in generalizing the effect of the autobiographical process. The conclusion reached is that autobiography is inherently centrifugal: it moves away from the center of cultural thinking because its “truth” bolsters itself on dialogical process which does not depend on a fixed authority but rather on communicative exchange. As an example of exchange, autobiography’s central truth is that it returns to a “unique point of origin”, namely the self, only to reconnect to the other in a potentially eternal exchange of responsiveness moving away from the center.
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  • Date Issued: 2002

Self-respecting practical reason: an analysis of self-respect and its implications for practical reason

  • Authors: Roberts, Deborah Joan
  • Date: 2002
  • Subjects: Williams, Bernard Arthur Owen -- Ethics , Ethics, Modern -- 20th century , Self-esteem
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2719 , http://hdl.handle.net/10962/d1002849 , Williams, Bernard Arthur Owen -- Ethics , Ethics, Modern -- 20th century , Self-esteem
  • Description: What should I do? As long as I am aware of the relevant facts of the situation and deliberating soundly, Bernard Williams argues that I should do what I want to do. It makes no sense to say that there are reasons that are fixed objects of concern, or values, that exist for an agent regardless of what she is in fact motivated to do. Reasons, for Williams, are hypothetical. I argue that he takes this view of practical reason because of a prior answer to the question “How should I live?”. A universal account of the good life would mean an account of values, or interests, that all human beings should have. Williams thinks it is not possible to give a universal account of the good life for human beings; any such account must be constructed out of the particular reasons of a community. But, he takes a constructivist view of the good life because he thinks that to be universal an account of the good life would have to be objective. Since objectivity cannot be achieved, he argues, neither can universality. Williams is only half right. That objectivity is not possible is inconsequential. A foundation for ethics has to be internal, but this does not preclude it being universal. I develop such a foundation based on the Aristotelian conception of human nature. A life cannot be wholly good if it is not self-respecting. Moreover, self-respect fits the framework for the specification of the good life that this foundation provides: I argue that self-respect can be shown to have a structure which provides an account of real interests - reasons that are objects of fixed concern. As such, reasons recognise rather than construct the good, making categorical reasons possible. A person can have a reason to change or act, even if reason itself cannot effect that change or action. Thus, I can be wrong about what I should do not only by being wrong about what would count as a satisfaction of my interests, but also by being wrong about what my interests are.
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  • Date Issued: 2002

English in the prison services: a case of breaking the law?

  • Authors: De Klerk, Vivian A , Barkhuizen, Gary
  • Date: 2002
  • Language: English
  • Type: Article
  • Identifier: vital:6133 , http://hdl.handle.net/10962/d1011585
  • Description: In this paper we report on an investigation into the use of English in a prison in the Eastern Cape Province, run by the Department of Correctional Services (CS) five years after the declaration of an official multilingual policy. The investigation consisted of a range of interviews and observations in this institution, aimed at establishing the extent to which the national language policy is actually being implemented on the ground. Findings suggest that the use of English predominates in the high, official domains, that there is a marked avoidance of Afrikaans, and that Xhosa, the main language of the Eastern Cape Province, increasingly occupies the lower, unofficial domains. Tensions between policy and practice are discussed, and it is argued that the CS has shown that pragmatism is a much stronger force than ideology. While the roles of Xhosa and Afrikaans appear to be in the process of reversing in the Grahamstown prison, English has emerged as stronger there than it has ever been before. And because it will continue to be a necessary prerequisite for the mobility and promotion of staff in the country as a whole, and the lingua franca for an increasingly mobile criminal population (which means the prisons are likely to become increasingly linguistically diverse, rather than settling into regional patterns), everyone will have to have some proficiency in English, which, ironically, will promote and strengthen it even more.
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  • Date Issued: 2002

Dynamics of early stage fishes associated with selected warm temperate estuaries in South Africa

  • Authors: Strydom, Nadine Amelia
  • Date: 2002
  • Subjects: Estuarine fishes -- South Africa Fishes -- Infancy -- South Africa Estuarine ecology -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5262 , http://hdl.handle.net/10962/d1005106
  • Description: Early stage fishes, namely larvae and early juveniles, were collected from 12 estuaries and associated habitats in the warm temperate region of South Africa between July 1998 and December 2000. This study served to provide new information and expand on existing knowledge of early stage fish assemblages associated with various types of Eastern Cape estuaries. A total of 65 536 predominantly postflexion fish larvae were collected. Together with early juveniles, taxa comprised 72 species from 25 teleost fish families. Surf zones associated with two intermittently open estuaries showed that estuary-dependent marine species predominated in this zone. Early stage fishes responded positively during natural estuary opening events and concentrated along the estuary outflow plume, suggesting that cueing from estuary and/or river water may be taking place. A habitat study in the Swartkops Estuary, using light traps, showed that newly recruited larval fishes concentrated along the margins of the estuary and unlike their older juvenile counterparts, were poorly represented in eelgrass beds. A multi-estuary comparison, including seven permanently open and five intermittently open estuaries, indicated that early stage fish assemblages were more diverse than indicated by past investigations. Early stage fishes were also shown to concentrate in the mesohaline regions of these estuaries. Studies of estuaries with altered freshwater flow regimes were also included in the research. A regulated release of dam water in the euhaline Kromme Estuary failed to induce a cueing response from estuary-dependent marine fish larvae. This project showed that large amounts of freshwater are required to reverse the negative effects of river impoundments. The release study did show that estuary-resident fishes were sensitive to small natural pulses of freshwater and responded by spawning. However, excessive river supply through an inter-basin water transfer scheme was shown to have a flushing effect on the larvae and early juveniles of the estuary-resident Gilchristella aestuaria in the upper reaches of the Great Fish Estuary. This effect was evident in comparisons with the freshwater starved Kariega Estuary where concentrations of G. aestuaria, a species usually more abundant in freshwater rich estuaries, were considerably higher. This finding suggests that freshwater minima and maxima be considered when assessing and managing estuarine systems.
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  • Date Issued: 2002

The electrochemical hydroxylation of aromatic substrates

  • Authors: Rautenbach, Daniel
  • Date: 2002
  • Subjects: Aromatic compounds , Hydroxylation
  • Language: English
  • Type: Thesis , Masters , MTech (Chemistry)
  • Identifier: vital:10959 , http://hdl.handle.net/10948/94 , Aromatic compounds , Hydroxylation
  • Description: The electrochemical hydroxylation of aromatic substrates was investigated in some detail, with the view to develop a method, which could produce dihydroxybenzenes in acceptable yields. Of particular interest was the selectivity and yield of the 1,4-dihydroxybenzenes. Two distinctly different methods were investigated in order to achieve this goal, acyloxylation and direct electrochemical hydroxylation. Acyloxylation is the process where radical cations generated at the anode undergoes nucleophilic attack by acetate anions. The resulting aromatic acetates so produced can then be hydrolysed to the phenolic compounds. Two nucleophile systems were considered in the investigation, acetates (acetoxylation) and trifluoro-acetates (trifluoro-acetoxylation). These investigations were conducted under a variety of conditions using phenol and phenyl acetate as starting materials. From the results it was, however, concluded that the acetoxylation of these aromatic compounds occurs in unacceptable product and current yields. Trifluoro-acetoxylation on the other hand showed promise, but due to the nature and cost of the reagents it was deemed to be an impractical process. Direct electrochemical hydroxylation: in which the radical cations produced at the anode undergoes nucleophilic attack by water producing the corresponding dihydroxybenzenes. These dihydroxybenzenes are then further oxidised to the benzoquinones, which then undergo reduction at the cathode in order to produce the corresponding dihydroxybenzene. In this process phenol, 2-tert-butylphenol and 2,6-di-tert-butylphenol were investigated as substrates. The results indicated that the yield towards the 1,4-dihdroxybenzenes increased as the degree of substitution on the ring increased.
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  • Date Issued: 2002

Effects of Axial Ligands on the Photosensitising Properties of Silicon Octaphenoxyphthalocyanines

  • Authors: Maree, Machiel David
  • Date: 2002
  • Subjects: Ligands , Photochemotherapy , Phthalocyanines
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4553 , http://hdl.handle.net/10962/d1018246
  • Description: Various axially substituted Silicon octaphenoxyphthalocyanines were synthesised as potential photosensitisers in the photodynamic therapy of cancer. Conventional reflux reactions were used for synthesis as well as new microwave irradiation reactions, wherein the reaction times were decreased tenfold with a marginal increase in reaction yield and product purity. An interesting series of oligomeric (dimer to a nonamer) silicon octaphenoxyphthalocyanines were also successfully synthesised in a reaction similar to polymerisation reactions. These compounds were found to undergo an axial ligand transformation upon irradiation with red light (> 600 nm) in dimethylsulphoxide solution. All the ligands were transformed into the dihydroxy silicon octaphenoxyphthalocyanine with varying degrees of phototransformation quantum yields ranging in order from 10⁻³ to 10⁻⁵ depending on the axial ligand involved. During and after axial ligand transformations a photodegredation of the dihydroxy silicon octaphenoxy phthalocyanine was observed upon continued irradiation. The oligomers were found to undergo the same axial ligand transformation process with a phototransformation quantum yield of 10⁻⁵ The singlet oxygen quantum yields of the unaggregated monomeric silicon octaphenoxy phthalocyanines were all found to be approximately 0.2 with the exception of a compound with two (trihexyl)siloxy axial substituents that had a singlet oxygen quantum yield of approximately 0.4 in dimethylsulphoxide solutions. The oligomers showed a surprising trend of an increase in singlet oxygen quantum yield with an increase in phthalocyanine ring number up to the pentamer and then a dramatic decrease to the nonamer. The triplet quantum yield and triplet lifetime were determined by laser flash photolysis for selected compounds and no correlation was observed with any of these properties and the singlet oxygen quantum yields. These selected compounds all fluoresce and a very good correlation was found between the fluorescence lifetimes determined experimentally by laser photolysis and the Strickler-Berg equation for the non-aggregated compounds. Electrochemical measurements also indicate the importance of the axial ligands upon the behaviour of the phthalocyanines as cyclic voltammetric behaviour was determined by the nature of the axial ligand.
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  • Date Issued: 2002

Biological generation of reactive alkaline species and their application in a sustainable bioprocess for the remediation of acid and metal contaminated wastewaters

  • Authors: Van Hille, Robert Paul
  • Date: 2002
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:21049 , http://hdl.handle.net/10962/6129
  • Description: This project focused on the development of an integrated biological system for the treatment of acidic and metal-laden effluents, based on the sustainable biological generation of reactive alkaline species. Initial studies concentrated on the binding and accumulation of heavy metals by biomass of the cyanobacteria, Spirulina sp. Metal binding was rapid, with saturation reached in 30 minutes, and followed an affinity series of Pb > Cu > Zn >>Fe. The binding capacity of the Spirulina for each of the metals was relatively low when compared to a range of other biosorbents. The toxicity thresholds of the algae was determined for copper and zinc. These were low (10umoles/g) and as such, the algae were not suitable for application in a treatment system in which they came into direct contact with the toxic metals. The algae were able to increase the pH of the surrounding medium. This occurred as a result of the accumulation of inorganic carbon, from bicarbonate, as a response to low concentrations of carbon dioxide in the medium. The resulting release of a hydroxide ion into solution led to the increase in pH. The increase in pH was shown to be due to a reduction in acidity, rather than an increase in alkalinity. The enzyme carbonic anhydrase was shown to be pivotal in this system. Attempts to determine the enzyme activity directly were unsuccessful, due to the inherent inaccuracy of the assay system. An indirect method of determining enzyme activity, by measuring changes in the carbonate species equilibrium, was developed. Under optimal conditions Spirulina was able to reduce the acidity by an amount equivalent to the addition of 3670umoles NaOH g·' h·'. Predictive modelling showed that this enhanced the potential of the medium to effect metal precipitation. For the algal system to be sustainable, a readily available source of bicarbonate was needed. This was achieved by the oxidation of organic carbon, under sulphidogenic conditions, by a bacterial consortium isolated from the anaerobic component of a facultative pond. The consortium was shown to consist of sulphate reducing (most likely Desulvovibrio and Desulfotomaculum)and acetogenic bacteria. Sulphate removal rates of 500mg 1·' day·' and 135mg 1·' day·' were achieved in a 21 agitated and 281 upflow reactor respectively. The bicarbonate generation rate in the 281 reactor was calculated as 4033umoles 1·' day·', which proved sufficient to act as a feed for the algal system. Sparging the anaerobic digester overflow with air and nitrogen resulted in a reduction in the aqueous sulphide concentration. Using nitrogen, a 70% recovery of sulphide, as H2S gas, was achieved in 60 minutes, while with air, this dropped to 40%, due to the oxidation of the aqueous sulphide. The stripping ofH2S resulted in an increase in pH. The H2S gas was used for the selective precipitation of copper and lead in the integrated system. The dynamics of metal precipitation was investigated. For simple reactions, between individual IV metal and base species, it was possible to generate an accurate predictive model and confirm the precipitating species using wavelength dispersive X-ray spectroscopy (WDS). In more complex systems, where precipitation of the artificial acid mine drainage was examined, the predictive modelling and WDS could not accurately describe the system. The addition of aqueous sulphide to copper and iron resulted in the formation of metastable, amorphous precipitates, which remained in suspension. Ageing of the copper precipitate resulted in the evolution of a stable crystalline structure (covellite) and the aggregation and settling of the precipitate. In the case of iron, the amorphous precipitate underwent oxidation before a stable iron sulphide could evolve and the settled precipitate was an iron oxide or oxyhydroxide. The artificial acid mine drainage was treated with sulphide, hydroxide, anaerobic digester overflow and algal overflow. The best metal removal was achieved with the sulphide and hydroxide, while the algal overflow outperformed the anaerobic digester overflow. The precipitate generated by the addition of sulphide was the most compact, followed by the algal overflow, the anaerobic digester overflow and the hydroxide. Efficient precipitation of all the heavy metals, except manganese, was achieved using the algal overflow at an acidity to alkalinity ratio of 1 :2. This ratio was selected for use in the pilot system. The Spirulina based pilot system was effectively used to treat an effluent from the Black Mountain base metal mine. The necessity to maintain the algae in suspension and avoid biomass washout were practical considerations which counted against this system. The replacement of the Spirulina by Oscillatoria, which adhered to a solid support, overcame these problems. The integrated biological system was able to effectively treat an artificial acid mine drainage for 90 days, reducing the concentration of all metals, except manganese, to below the acceptable environmental risk levels. The treatment of the final effluent in a second anaerobic digester reduced the manganese concentration to 4.5uM and proved that the sulphate reducing bacteria could be cultivated on enriched, partially treated acid mine drainage. The integrated biological treatment system performed well, effectively treating an effluent modelled closely on the quality of the water being discharged from the East Rand Basin. The cost of such a system would be considerably less than a "high tech" physico-chemical system. This, coupled with the potential long term sustainability of a biological system, would make it a potentially attractive option for the treatment of future acid mine drainage discharges.
  • Full Text:
  • Date Issued: 2002

An investigation of the neuroprotective effects of estrogen in a model of quinolinic acid-induced neurodegeneration

  • Authors: Heron, Paula Michelle
  • Date: 2002
  • Subjects: Estrogen , Quinolinic acid , Nervous system -- Degeneration
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3759 , http://hdl.handle.net/10962/d1003237 , Estrogen , Quinolinic acid , Nervous system -- Degeneration
  • Description: The hippocampus, located in the medial temporal lobe, is an important region of the brain responsible for the formation of memory. Thus, any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include the neurotoxin, Quinolinic acid. Quinolinic acid (QUIN) is a neurotoxic metabolite of the tryptophan-kynurenine pathway and is an endogenous glutamate agonist that selectively injures and kills vulnerable neurons via the activation of the NMDA class of excitatory amino acid receptors. Estrogen is a female hormone that is responsible for reproduction. However, in the last decade estrogen has been shown to exhibit a wide range of actions on the brain, including neuroprotection. Estrogen has been shown to exhibit intrinsic antioxidant activity and protects cultured neurons against oxidative cell death. This is achieved by estrogen’s ability to scavenge free radicals, which is dependent on the presence of the hydroxyl group at the C3 position on the A ring of the steroid molecule. Numerous studies have shown that estrogen protects neurons against various toxic substances and may play a role in delaying the onset of neurodegenerative diseases, such as Alzheimer’s disease. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. The study aims to elucidate and further characterise the mechanism behind estrogen’s neuroprotection, using QUIN as a model of neurotoxicity. Initial studies confirm estrogen’s ability to scavenge potent free radicals. In addition, the results show that estrogen forms an interaction with iron (II) and also acts at the NMDA receptor as an agonist. Both mechanisms reduce the ability of QUIN to cause damage to neurons, since QUIN-induced toxicity is dependent on the activation of the NMDA receptor and the formation of a complex with iron (II) to induce lipid peroxidation. Heat shock proteins, especially Hsp 70 play a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. Estrogen has been shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that estrogen helps to protect against cellular protein damage induced by any form of stress the cell may encounter. The discovery of neuroprotective agents, such as estrogen, is becoming important as accumulating evidence indicates a protective role in vivo. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders. Considering how devastating diseases, such as Alzheimer’s disease, are to a patient and the patient’s families, the discovery of new protective agents are a matter of urgency.
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  • Date Issued: 2002

Theatre and science, with specific reference to Shelagh Stephenson's An experiment with an air pump (1999)

  • Authors: Van Niekerk, Dion
  • Date: 2002
  • Subjects: Science in literature , Stephenson, Shelagh -- Experiment with an air pump
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2152 , http://hdl.handle.net/10962/d1004270
  • Description: Science has featured intermittently as the subject of theatrical texts since Thomas Shadwell first represented the Renaissance scientist in The Virtuoso (1676). The late twentieth century, however, saw an incremental growth in theatre's interest in scientific exploration, a growth concommitant with the vast impact that science has had on technology, warfare and the machinations of political power. The tensions generated by the disjuncture between the rationality of science and the unpredictability of human society have provided a rich source of material for theatrical investigation into the human experience. The purpose of this thesis is twofold: to reveal some of the thematic concerns that emerge in this genre, and to examine the interplay between theatre and science. Shelagh Stephenson's An Experiment with an Air Pump (1999) provides a useful point of focus for this inquiry. By parallelling two time periods, exposing the scientific objectification of women and, in addition, opening up contemporary ethics for negotiation with the audience, Stephenson calls into question the objectivity and certainty of history, gender and ethical conduct. These she presents as dynamic and evolving fields of discourse that contribute to, but do not solely constitute, knowledge and understanding of the world. An Experiment with an Air Pump also displays an awareness, through its metatheatricality, of theatre itself as an imaginative, subjective discourse which parallels the more intuitive and personal aspects of scientific exploration. The play functions as a microscope, bringing into focus a contemporary world in which traditional systems of understanding and knowledge need to be reassessed and reinvented.
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  • Date Issued: 2002

Identification of Cowdria ruminantium proteins that induce specific cellular immune responses

  • Authors: Van Kleef, Mirinda
  • Date: 2002
  • Subjects: Ruminants--Pathogens Heartwater
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4061 , http://hdl.handle.net/10962/d1004373
  • Description: Cowdria ruminantium (Cowdria) is an obligate intracellular pathogen that causes heartwater in ruminants. Cellular immunity and the type I cytokine IFN-γ have been implicated in protective immunity to heartwater. The aim of this thesis was to identify proteins of the Welgevonden isolate of Cowdria that induce lymphocyte proliferation and IFN-γ production. Differential centrifugation was found to be the simplest and most efficient method of Cowdria purification. Cowdria organisms were fractionated into their constituent proteins of between 11 and 168 kDa by continuous flow electrophoresis. The resulting fractions were tested for their ability to stimulate lymphocyte proliferation in vitro. In an attempt to simulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with the proteins fractions. In a parallel study, four cattle were immunised with inactivated Cowdria to determine whether their lymphocytes responded similarly. Cowdria-specific proliferation was detected for only a brief period after immunisation by infection with live organisms. This response was only detected again two to three years later. In contrast, PBMC from animals immunised with inactivated organisms were continuously responsive for at least three years. Only Cowdria proteins with molecular masses of 11, 12, 14 to 17 and 19 to 23 kDa induced proliferative responses in PBMC obtained from all six animals. Cell surface phenotypic analysis of Cowdria specific T-cell lines indicated that CD4⁺ lymphocytes were enriched over time with a concomitant increase in antigen-specific proliferation and IFN-γ production. Proteins of molecular masses 13 to 18 kDa induced CD4⁺ lymphocyte proliferation and IFN-γ production by T-cell lines from all the animals tested. Antibodies raised in a chicken and in rabbits to these low molecular weight proteins had low titres and specificity. Two-dimensional electrophoresis indicated that proteins within a single molecular weight range comprised several components with different pIs, revealing the complexity of the Cowdria proteome. This complicates the search for potentially protective antigens. Nevertheless, since they cause proliferation and IFN-γ production by lymphocytes from immunised cattle, these low molecular weight proteins merit further investigation as potential vaccine antigens. , Author: Mirinda van Kleef neé Rossouw
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  • Date Issued: 2002

The selection paradox: selecting and evaluating trainee psychologists in the context of narrative theory

  • Authors: Kaschula, Joanne
  • Date: 2002
  • Subjects: Psychologists -- Training of -- South Africa , Psychology -- Study and teaching -- South Africa , Psychologists -- Selection and appointment -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSocSc
  • Identifier: vital:3001 , http://hdl.handle.net/10962/d1002510 , Psychologists -- Training of -- South Africa , Psychology -- Study and teaching -- South Africa , Psychologists -- Selection and appointment -- South Africa
  • Description: Psychology has become an increasingly popular discipline for study in the South African context, with the number of students enrolling for courses increasing rapidly. The selection and evaluation of trainee psychologists is a complex and contested issue. With so few students reaching Masters level and the changing needs of the South African context, it becomes imperative that only the most suitable candidates are selected for entry into the field of professional psychology. This study focuses on the selection process of trainee psychologists at an institution that incorporates the narrative philosophy in both the selection and training of candidates. The question is raised, whether it is possible to utilize narrative principles in a process that is intended to judge and evaluate candidates? This presents a paradox. The paradox is illuminated in both the intentions behind the narrative questions in the application form and in the candidates' experiences of responding to these. The conclusion reached is that the narrative philosophy makes for an enriching and creative experience of the selection process for candidates but this however, does not ameliorate the negative effects of evaluation and the 'gaze'.
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  • Date Issued: 2002

Minding the gaps – an investigation into language policy and practice in four Eastern Cape districts

  • Authors: Probyn, Margie , Murray, Sarah , Botha, Liz , Botya, Paula , Brookes, Margie , Westphal, Vivian
  • Date: 2002
  • Language: English
  • Type: Article
  • Identifier: vital:6109 , http://hdl.handle.net/10962/d1009739
  • Description: South Africa's new Language in Education Policy (LiEP) has been described as one of the most progressive in the world but few schools have implemented it. This article describes research that investigates the gap between the policy goals and what is actually happening in schools in four districts in the Eastern Cape. The research attempts to make explicit community and school language practices and the factors that support or frustrate the formation and enactment of a school language policy in these four linguistically diverse sites. It appears that school governing bodies are not well equipped to make decisions about school language policy which meet the requirements of the national LiEP and economic imperatives to acquire English override considerations of multilingualism and additive bilingualism as expressed in the policy.
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  • Date Issued: 2002

The development of a financial plan to partly cover the cost of frail care in a retirement village in George

  • Authors: Brink, F J
  • Date: 2002
  • Subjects: Older people -- Care -- South Africa , Frail elderly -- Medical care -- South Africa -- George , Frail elderly -- Care -- South Africa -- George
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:10919 , http://hdl.handle.net/10948/84 , Older people -- Care -- South Africa , Frail elderly -- Medical care -- South Africa -- George , Frail elderly -- Care -- South Africa -- George
  • Description: The world population is ageing, and this is also relevant to South Africa. At the same time the potential support ratio (the number of persons aged 15 to 64 years per one older person aged 65 years or older) is falling, and the dependency burden on potential workers increases. To alleviate the financial burden on the aged, and their families, it has become necessary to develop a financial plan to cover the cost of frail care. The overall purpose of this research is to determine whether any financial plans exist which are relevant. If nothing existed, a plan had to be developed. The research methodology for this study comprised the following steps: Firstly, the demographics of the world and South Africa were researched. The concept of frail (long-term) care in the United States of America and New Zealand was investigated to determine what is available. The subsidisation concept of the South African Government towards caring for the elderly was also investigated. Secondly, a questionnaire was sent to the residents of five retirement complexes in George to determine their interest in such a plan. The records of the frail care unit that these residents utilise were analysed to determine the number of residents needing frail care. A comparative study of the cost of frail care in the Southern Cape was undertaken. Thirdly, two options to partly subsidise the cost of frail care were examined, where the first option covers the running cost, and the second option, subsidising one third of the frail care cost, builds up a sustainable fund after the first five year period. The funds of the second option can then be utilised in the subsequent years to increase the subsidisation portion of frail care cost. The final step of this study entailed the formulation of recommendations to implement the frail care nursing levy as soon as possible, with special attention given to the following: a) It must be compulsory for new residents to join the fund. b) A yearly capital amount of R100 000 or more is needed to sustain the fund. c) A contract must be drafted to set out all the rules and regulations to the residents. d) An attitude change amongst some residents is required. Individuals must realise that the success of this plan depends upon themselves and with the necessary support could make a significant contribution towards their own peace of mind if and when frail care is needed.
  • Full Text:
  • Date Issued: 2002
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