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Electrochemical studies of manganese tetraamminophthalocyanine monomer and polymer

  • Authors: Obirai, Joseph , Nyokong, Tebello
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290330 , vital:56738 , xlink:href="https://doi.org/10.1016/j.electacta.2003.11.006"
  • Description: Manganese tetraaminophthalocyanine (MnTAPc) has been synthesised. The cyclic voltammetry and spectroelectrochemistry of the complex have been examined. Spectroelectrochemistry has been used to confirm that the species synthesised in this work contains MnIII, giving (OH)MnIIITAPc. The oxidation and reduction couples obtained from cyclic voltammetry have been assigned to MnIVPc−/MnIVPc2− (couple I), MnIVPc2−/MnIIIPc2− (couple I′), MnIIIPc2−/MnIIPc2− (couple II) and MnIIPc2−/MnIIPc3− (couple III). Electropolymerization of the MnTAPc onto either the indium tin oxide or glassy carbon electrode results in the in the formation of a poly-MnTAPc. The poly-MnTAPc shows improved reversibility at low pH. The poly-MnTAPc electrode was employed to analyse glycine.
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Emerging patterns of abstraction in environmental education: A review of materials, methods and professional development perspectives

  • Authors: O'Donoghue, Rob B , Russo, Vladimir
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/373610 , vital:66707 , xlink:href="https://doi.org/10.1080/1350462042000258170"
  • Description: The epistemic unconscious is the history of the field. And it is clear that, to secure some chance of really knowing what one is doing, one has to unfold what is inscribed in the various relations of implication in which the thinker and his thoughts are caught up, that is, the presuppositions he engages and the inclusions and exclusions he unwittingly performs. (Bourdieu, 2000, p. 99).
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Environmental education research and social change: Southern African perspectives

  • Authors: Lotz-Sisitka, Heila
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/182709 , vital:43855 , xlink:href="https://doi.org/10.1080/1350462042000258143"
  • Description: Environmental issues and risks in southern Africa have, like elsewhere in the world, their roots in the structures and orientations of modern societies. In modernist fashion, we draw on education and research to address socio-ecological concerns. In 1995 Eureta Janse van Rensburg, then Murray and Roberts Chair of Environmental Education at Rhodes University,1 undertook a study to identify environmental education research priorities, and through her study she provided a description of research in environmental education as a ‘landscape of shifting priorites’ (Janse van Rensburg, 1995). The papers in this journal offer a contemporary ‘snapshot’ of the landscape of environmental education research in southern Africa, illustrating a fresh range of ‘shifting priorities’.
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Harvesting impacts on commonly used medicinal tree species (Catha edulis and Rapanea melanophloeos) under different land management regimes in the Mpumalanga Lowveld, South Africa

  • Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181379 , vital:43728 , xlink:href="https://doi.org/10.4102/koedoe.v47i2.77"
  • Description: Harvesting of products from plants in the wild is widespread throughout southern Africa. Particularly important products are plant parts used in traditional medicine. However, the impacts of harvesting practices are rarely quantified, with as yet insufficient generic rules across species and life forms. This limits the predictive ability to monitor and manage the affected populations. This paper examines the harvesting impact on two popular woody medicinal species used throughout sub-Saharan Africa, namely Catha edulis (Vahl) Forssk. ex Endl. (bushman’s tea) and Rapanea melanophloeos (L.) Mez. (Cape beech). In both species, basal diameters, heights, and the number of size classes in the harvested populations were lower than in unharvested. Densities of harvested populations were higher in both species, including densities of young plants, but the frequency of individuals in larger size classes was lower. The populations of both species being harvested for medicinal products appeared to be withstanding the current levels of harvesting, but the population structure of C. edulis populations being harvested for poles on the roadside and near human settlements had been substantially altered. Despite the resilience of the two species to harvesting for medicinal products, loss of habitat or changes in land use pose a threat to a number of the assessed populations.
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Integrating indigenous ecological knowledge and customary sea tenure with marine and social science for conservation of bumphead parrotfish (Bolbometopon muricatum) in the Roviana Lagoon, Solomon Islands

  • Authors: Shankar, Aswani , Hamilton, Richard
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/439945 , vital:73722 , xlink:href="https://doi.org/10.1017/S037689290400116X"
  • Description: Indigenous ecological knowledge and customary sea tenure may be integrated with marine and social science to conserve the bumphead parrotfish (Bolbometopon muricatum) in the Roviana Lagoon, Western Solomon Islands. Three aspects of indigenous ecological knowledge in Roviana were identified as most relevant for the management and conservation of bumphead parrotfish, and studied through a combination of marine science and anthropological methods. These were (1) local claims that fishing pressure has had a significant impact on bumphead parrotfish populations in the Roviana Lagoon; (2) the claim that only small bumphead parrotfish were ever seen or captured in the inner lagoon and that very small fish were restricted to specific shallow inner-lagoon nursery regions; and (3) assertions made by local divers that bumphead parrotfish predominantly aggregated at night around the new moon period and that catches were highest at that time. The research supported claims (1) and (2), but did not support proposition (3). Although the people of the Roviana Lagoon had similar conceptions about their entitlement rights to sea space, there were marked differences among regional villages in their opinions regarding governance and actual operational rules of management in the Lagoon. Contemporary differences in management strategies resulted from people's historical and spatial patterns of settlement across the landscape and adjoining seascapes, and the attendant impact of these patterns on property relations. This was crucial in distinguishing between those villages that held secure tenure over their contiguous sea estates from those that did not. Indigenous ecological knowledge served to (1) verify that the bumphead parrotfish was a species in urgent need of protection; (2) explain how different habitats structured the size distribution of bumphead parrotfish; (3) identify sensitive locations and habitats in need of protection; and (4) explain the effect of lunar periodicity on bumphead parrotfish behaviour and catch rates. Secure customary sea tenure identified locations best suited to bumphead parrotfish management programmes, with a greater likelihood for local participation and programme success. The information was used to establish two marine protected areas in the region for bumphead parrotfish conservation.
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Scientific evaluation in women’s participatory management: monitoring marine invertebrate refugia in the Solomon Islands

  • Authors: Shankar, Aswani , Weiant, P
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/439983 , vital:73725 , xlink:href="https://doi.org/10.17730/humo.63.3.r7kgd4thktmyf7k1"
  • Description: This paper summarizes the results of a women’s community-based marine protected area that has been successful in sustaining invertebrate biological resources and in promoting strong community support. We outline the project and the associated biological results, describe the processes involved in attaining a committed level of community participation, and review the lessons learned during the project’s implementation. We attribute the project’s preliminary success—improved shellfish biomass, enhanced local environmental awareness, and the reinvigoration of cultural management practices—to the following factors: 1) the high level of participatory involvement and community leadership; 2) the local perception that shell beds have recovered rapidly and the role that scientific evaluation has played in reinforcing this notion; 3) a research program that is cross-fertilizing indigenous and scientific ecological knowledge; 4) the unique marine tenure system that allows for the project’s development and the area’s policing; and 5) the tangible economic incentives created by the development project, which ultimately empowers local women. We hope that the project’s findings can be generalized to other regions of the world with operational sea-tenure regimes and that it can help to make the establishing of community-based marine protected areas (CBMPAs) across the Pacific region more effective.
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Socio-economic differentiation in the trade of wildlife species for traditional medicines in the Lowveld, South Africa: Implications for resource management initiatives

  • Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M , Fairbanks, Dean H K
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/183071 , vital:43909 , xlink:href="https://doi.org/10.1080/13504500409469832"
  • Description: Surveys of trade in wildlife products utilised in traditional medicine were conducted between 1997 and 1999 on the western boundary of the Kruger National Park, South Africa. Although the extent of trade and numbers of people operating in this sector were lower than other regions of South Africa, this study again highlighted the value of indigenous wildlife products to subsistence economies. Apart from cultural diversity, socioeconomic differentiation occurred at a number of levels. (i) There were socio-economic differences between the traders and vendors. (ii) Gender differences were apparent, with women earning significantly less than men and having to undergo more social challenges in their operation in the market place. (iii) Operational differences were noted between the vendors and traders, as well as between the street and pension day vendors. (iv) Multidimensional Scaling (MDS) highlighted the socio-economic differentiation at the household level, emphasizing in particular one of the most vulnerable groups, the elderly. The potential influence of this socio-economic differentiation needs to be considered during the development of Community-Based Conservation programmes, if the dual aims of conserving biodiversity and improving the lives and livelihoods of those who traditionally rely on medicinal plants are to be met.
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Study South Africa

  • Authors: International Education Association of South Africa (IEASA) , Van Essche, Alexandra
  • Date: 2004
  • Subjects: Education, Higher -- South Africa , Education and globalization -- South Africa Student mobility -- Africa International education -- South Africa Education, Higher -- International cooperation , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/65333 , vital:28746 , ISBN 0620247290
  • Description: [Message from the President of IEASA, Dr Roshen Kishun]: The fourth edition of Study South Africa; Guide to South African Tertiary Education coincides with a momentous event in the history of South Africa. It is the 10th anniversary of the democracy after the 1994 elections that ended apartheid. It is time to celebrate the achievements, the development strides, and the reintegration of South Africa into the world community. The International Education Association of South Africa (IEASA) welcomes the new Minister of Education, Ms Naledi Pandor, elected to the Cabinet after the April 2004 elections. We wish her well in her new and demanding portfolio. We are confident that the Minister will support the tertiary education sector to develop linkages between international education, skilled migration and the transition to knowledge economies. While we believe that a free and democratic country may be the most powerful attraction for international students wishing to study in South Africa there are other reasons. South Africa is rated as a technological powerhouse on the African continent. Comparatively South Africa’s educational infrastructure can be compared with the best in the world. Its research sector is by far the strongest in Africa. The country has adopted English as one of its official languages and it is the main medium of instruction in the tertiary education sector. A significant factor which makes South African qualifications attractive is the relatively lower cost of study. Study in South Africa offers the best of both worlds to international students, combining the experience of living in Africa with the opportunity to obtain quality education at a fraction of the cost. In the ten years since 1994, the opening-up of the tertiary education sector in South Africa is evidenced by the dramatic increase of international students studying in the South African public education sector from about 13 000 to more than 47 000 in 2002. While the headcount numbers include distance education students, it is possible that South Africa is currently the leading host country for international students in Africa. An IDP report predicts that by 2025 almost eight million students will be educated trans-nationally. The growth in international student numbers presents South Africa with some exciting challenges in the global context. South Africa is expected to become one of the top nations in the world hosting international students in the next ten yean. Study South Africa is published in the middle of one of the most intense periods of change when the South African education system is being restructured to eliminate duplications created under the apartheid system. The number of public institutions is being reduced from 36 to 23 through mergers and incorporations. The binary divide that existed in the public higher education system pre- 2002, where there were 21 universities and 15 technikons is blurred by the creation of the universities of technology. In spite of the massive transformation, the South African higher education sector has much to offer in the form of quality education, advanced research facilities and internationally recognized qualifications. The information provided in this Guide introduces the individual institutions, their academic offerings, support services provided and other relevant details needed to make a choice of study destination Study South Africa is also a useful tool in the development of a strategy to market South African higher education into the competitive world of international education. The decision by IEASA to develop a marketing strategy is not only a reaction to global higher education pressures, but is also an acknowledgement of South Africa’s return to the global higher education community and in identified geographical areas. IEASA realised that past isolation can only be overturned by conscious new strategies. This 'marketing initiative’ meant that the presence of South Africa was highly visible at some of the leading forums dealing with international education in the world. Study South Africa is undertaken by IEASA in association with the South African Vice-Chancellors Association (SAUVCA) and the Committee of Technikon Principals (CTP). These organizations themselves are set to merge in the near future. We appreciate the support of the Council on Higher Education (CHE), the South African Qualifications Authority (SAQA), Unitech (Higher Education professional body for marketing, communication and development), and Professor T Mthembu. We are most grarefril to Karen MacGregor, our specialist writer, who compiled the excellent articles in this publication on achievements during the ten years of transformation. I wish to take this opportunity of thanking all those who made contributions for their support and all the tertiary education institutions in the public education sector for their participation. We are grateful to the Department of Foreign Affairs for the distribution of the Guide abroad and to members of the IEASA publications committee for their input. We appreciate the support of Artworks Publishing for working under pressure to meet publications deadline. Special thanks are due to Zandile Wanda for the work in coordinating the response from the tertiary education sector and to Alexandra van Essche for compiling and producing the Guide. Without their efforts it would not have been possible to publish the Guide. , 4th Edition
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Synthesis and photochemical studies of substituted adjacent binaphthalophthalocyanines

  • Authors: Seotsanyana-Mokhosi, Itumeleng , Nyokong, Tebello
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289883 , vital:56689 , xlink:href="https://doi.org/10.1142/S1088424604000568"
  • Description: Adjacent phthalocyanines with a binaphthalo backbone and phenoxy substituents were synthesized and their photochemical properties were investigated. The adjacent phthalocyanines are the binaphthalophthalocyanines, with the phenoxy, 4-tert-butylphenoxy and the sulfophenoxy substituents, respectively and bis-binaphthalophthalocyanine which has an extended π conjugation system and larger singlet oxygen quantum yield compared to the other compounds. The presence of the phenoxy substituents as well as the binaphthalo bridge does not cause a marked difference on the fluorescing properties of these complexes when compared to zinc phthalocyanine. The binaphthalo backbone allowed the molecules to photoswitch during photolysis affording them very high photostability.
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The fuelwood crisis in southern Africa: Relating fuelwood use to livelihoods in a rural village

  • Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181402 , vital:43730 , xlink:href="https://doi.org/10.1023/B:GEJO.0000033597.34013.9f"
  • Description: The aim of the paper is to examine wood as a source of fuel energy in rural South Africa and factors influencing its usage. The analysis is based on household profiles and characteristics (e.g., gender, caste, population and income) in a livelihood framework. Fuelwood consumption was estimated to be 692 kg/capita, and 4343 kg/user household per annum, valued at $311 per household. Consumption was modelled in relation to informal and formal cash incomes, and population of children, female and male adults. However, only the population of female adults could significantly influence consumption of fuelwood. This implied that where there were more women in a household, consumption was likely to be high. This might be due to the majority of women doing the cooking and heating in the household. Any change in the value of cash income of households had no significant impacts on fuelwood consumed. Cash incomes might therefore not be strong determinants of the types of energy used by rural households. The average quantity of wood consumed for fuel energy in summer was not significantly different from consumption in winter. Some households perpetually used more wood than others. The study further showed that harvesting of wood for fuel energy is not opportunistic, but requires reallocation of time for other livelihood activities in times of shortage. The fuelwood crisis is not simple and not only about shortage of fuelwood and/or population growth but linked to household profiles and other livelihood strategies and subsequently vulnerability of households. These would require thorough investigation and understanding in relation to precise demand and supply data for fuelwood before the fuelwood problem can be sufficiently managed.
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The impact of commercial harvesting on Warburgia salutaris (‘pepper-bark tree’) in Mpumalanga, South Africa

  • Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181391 , vital:43729 , xlink:href="https://doi.org/10.1023/B:BIOC.0000029333.72945.b0"
  • Description: Commercialisation often increases the difficulty in managing harvested plant populations sustainably. The bark of the popular medicinal species, Warburgia salutaris (Bertol.f.) Chiov. (Canellaceae) (‘pepper-bark tree’), is widely traded throughout southern Africa. The impact of commercial harvesting on this Red Data species was assessed by comparing commercially harvested populations with populations growing on private land or in protected areas (termed ‘protected populations’) in Mpumalanga and Limpopo Province, South Africa. The basal diameters and heights of stems in commercially harvested populations were significantly lower than those of the protected populations. The density of young/small plants was low in all populations. W. salutaris is usually resilient to high levels of bark harvesting. In this study, 75% of heavily harvested stems (>10% of the stem below 2 m) coppiced (resprouted). However, individuals that had been affected by regular fires, or repeatedly harvested, appeared prone to a fungal disease and had high percentage mortality. The populations occurring on private land appeared the most vigorous. Habitat in one protected area had been reduced through the construction of a dam. In another, small W. salutaris populations exhibited a shrubby growth form, probably due to frequent fires. Our current knowledge for this species supports a global IUCN status of EN A4acd. Plant conservation needs to become a higher priority both within and outside protected areas. Commercially harvested populations should be better managed through improved harvesting techniques and monitoring. Cultivation levels urgently need to be increased. Further research should be conducted on factors limiting regeneration, including the most appropriate fire regime.
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The renaissance in optical spectroscopy of phthalocyanines and other tetraazaporphyrins

  • Authors: Nyokong, Tebello , Isago, Hiroaki
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
  • Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
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The value of many small vs. few large marine protected areas in the Western Solomon Islands

  • Authors: Shankar, Aswani , Hamilton, Richard
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/440050 , vital:73731
  • Description: Scientists and policy makers are universally promoting marine protected areas (MPAs) as a fisheries and ecosystem management tool. Experts generally agree that MPAs, particularly fully protected “no-take” zones, can enhance spawning stock biomass, allow for larval dispersal and the export of adults to adjacent non-protected areas, maintain species diversity, preserve habitat, and sustain ecosystem function (eg Bergen and Carr 2003; Johnson et al. 1999; Russ and Alcala 1999). In the case of tropical multi-species fisheries, in which absolute yields are difficult to predict and in which there are multiple users and fishing techniques, marine reserves also can act as precautionary tools to prevent overexploitation. Considering that orthodox fisheries management strategies have generally failed to prevent overfishing globally, the inception of MPAs as a management tool is of particular preventive significance (Russ 2002). Proponents of MPAs have broadly debated the appropriate size and number of MPAs that should be established in order to produce what a particular management prescription proposes to deliver. Some scientists argue that for MPAs to be effective they should cover areas in the magnitude of hundreds or even thousands of square miles, depending upon the type of environment (eg Beattie et al. 2002; Man et al. 1995; Walters 2000). Others have suggested that from a fisheries enhancement perspective, many small reserves in a network are preferred over fewer, larger reserves (eg Roberts et al. 2003). Other debates have centred on how much attention should be paid to science-driven vs. stakeholder-driven considerations when designing MPAs (eg Agardy 1997; Alder et al. 2002; Christie et al. 2003; Jones 2002).
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Zinc phthalocyanine photocatalyzed oxidation of cyclohexene

  • Authors: Sehlotho, Nthapo , Nyokong, Tebello
  • Date: 2004
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/289399 , vital:56629 , xlink:href="https://doi.org/10.1016/j.molcata.2004.05.010"
  • Description: Cyclohexene photooxidation catalyzed by zinc phthalocyanine (ZnPc) using either red or white light results in the formation of cyclohexenone, cyclohexenol, trans-cyclohexanediol, cyclohexene oxide and cyclohexene hydroperoxide. The product yield increased as follows: cyclohexenone > cyclohexenol > trans-cyclohexanediol > cyclohexene oxide > cyclohexene hydroperoxide. The mechanism for the formation of these products involves both singlet oxygen and radicals (Type II and Type I mechanisms, respectively). The catalyst degraded slowly when low light intensities were employed. The product yields were found to depend on the light intensity, the nature of solvent, irradiation time and the rate of photodegradation of the catalyst.
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Investment management: an analysis of the risk-return profiles of the South African and Kenyan stock markets

  • Authors: Ndungu, Stanley Ngaruiya
  • Date: 2003-03
  • Subjects: Uncatalogued
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10962/191305 , vital:45082
  • Description: This study analyses the risk-return profiles of securities and constructed portfolio of the South African and Kenya’s stock markets. The analysis is done with cognisance of the dynamism that characterizes contemporary financial markets especially in the face of globalisation. To this end the study inter alia, considers the impact of the technological, information and telecommunications revolution particularly with regard to trading, delivery and settlement period. It also considers the factors that influence the business environment in each of the two markets and how these affect their risk return profiles. Key among the findings of the study are that, only a few sectors and securities in both the South African and Kenyan markets (S % and less than 1 % respectively) exhibited very high risk-return profiles while most of the rest (32 % and 40 % respectively) recorded low risk-return profiles. Overall, the business environment in South Africa is evidently better when compared to that of Kenya. Consequently, each country’s business environment may be used to explain the high/low risk return profiles. , Thesis (MA) -- Faculty of Commerce, Economics and Economic History, 2003
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An investigation into the biological treatment of platinum refinery effluent using the plant Azolla Filiculoides

  • Authors: Marran, Vernon Edward
  • Date: 2003
  • Subjects: Uncatalogued
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10962/193453 , vital:45333
  • Description: In order to understand the effects of metals contained in effluent and to define effluent quality suitable for safe discharge to natural water streams, it is essential to understand the effects of the interaction of metal ions with plants. The availability of metal ions and their ability to bind to plants are dependent on the chemical speciation of metals and on the biological factors governing the availability of metals within the plant cells. This thesis will address both aspects and thereby propose a combination of an appropriate chemical and biological approach to the investigation of bioaccumulation of the plant Azolla Filiculoides. Laboratory studies have shown that varying concentrations of free metal ions in solution determine efficiency of metal uptake and that metal toxicity can also be detrimental to plant life and efficiency of metal recovery from solution. Many questions however, remain unanswered with regard to the application of a biological treatment for effluent discharge. This thesis includes the determination of metal speciation combined with the study of bioaccumulation of metals in plants and their effects from test- work utilising effluent generated from a Precious Metals Refinery (PMR). Plant species are known to differ widely in their tolerance to metals, however despite an abundant knowledge on molecular, biochemical and physiological effects of metals to plants, only a few general principles have been proposed to guide the prediction of tolerance differences. The properties of protective cellular responses as well as of the molecular target sites are important components in determining the intrinsic tolerance of a particular species to a metal. The role of the whole assembly of cellular ligands in buffering metal ions within the cells will be evaluated. Standard preparation methods combined with use of Inductively Coupled Plasma Emission Spectrophotometer (1CP) used for analytical analysis will be included to reflect analytical data in providing evidence to support a conclusion. The outcome of the test work utilising the aquatic plant Azoila has proven that it can be used as a process step to re-mediate effluent generated from Precious Metal Refining operations. This process offers an alternative to the classical chemical methods widely used in the Precious Metals Refining industry proving economically viable and ensuring environmental sustainability in comparison to the current known methods of effluent treatment. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2003
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Crystallographic Analysis and Structural Revision of a Spiroterpenoid Rearrangement Product

  • Authors: Lobb, Kevin A , Kaye, Perry T
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/449335 , vital:74812 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/122435"
  • Description: Single crystal X-ray analysis of a spiroterpenoid rearrangement product has revealed that its structure is, in fact, isomeric with the structure proposed previously – an observation that has significant mechanistic implications.
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Direct-use value of smallholder crop production in a semi-arid rural South African village

  • Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/181595 , vital:43750 , xlink:href="https://doi.org/10.1016/S0308-521X(02)00124-5"
  • Description: The monetary value of natural resources used by rural communities for subsistence is important when addressing issues affecting the livelihoods of impoverished rural households. There is therefore the need to attribute monetary values to non-marketed products from smallholder production systems in order to reliably account for resource availability and usage to further sound policy decisions. The objective of this paper is to present an empirical analysis of the direct-use and traded values of crop production by households, and to discuss the implications for policy development. The study was undertaken in combination with an evaluation of other livelihood sectors in Thorndale, a semi-arid rural village in the Limpopo province of South Africa. The net direct-use value of crops was estimated at $443.4 per household per annum across the village. Maize (Zea mays), watermelon (Citrullus, vulgaris), peanuts (Arachis hypogaea) and common beans (Phaseolus vulgaris) contributed over 90% to the total direct-use value of crops. Maize alone contributed 40% of this value per household at an estimated $652/ha. Marketing of resources was not a common practice, limited to only maize and peanuts. Farming was basically a rain-fed–mixed cropping system with low production inputs. Farmer support services, human capital development and tenure security were major areas identified for policy development.
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Electrochemical behavior and detection of dopamine and ascorbic acid at an iron (II) tetrasulfophthalocyanine modified carbon paste microelectrode

  • Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
  • Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
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Electrochemical behaviour of thiol-derivatised zinc (II) phthalocyanine complexes and their self-immobilised films at gold electrodes

  • Authors: Ozoemena, Kenneth I , Nyokong, Tebello
  • Date: 2003
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
  • Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
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