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Electrocatalytic studies of covalently immobilized metal tetra-amino phthalocyanines onto derivatized screen-printed gold electrodes

  • Authors: Mashazi, Philani N , Nyokong, Tebello
  • Date: 2015
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/249059 , vital:51774 , xlink:href="https://doi.org/10.1007/s00604-010-0438-6"
  • Description: Metal tetra-amino phthalocyanine complexes (MTAPc; where M is Co or Mn) were immobilized on screen-printed gold electrodes pre-modified with monolayers of benzylamino groups. The functionalized electrodes were then activated using benzene-1,4-dicarbaldehyde as a linker before MTAPc complexes were immobilized. The surface coverages for the modified electrodes confirmed the perpendicular orientation of the MTAPcs. The apparent electron transfer constant (kapp) for the electrodes is 2.2 × 10−5 cm.s−1 for both CoTAPc and MnTAPc modified electrodes as calculated with data from impedance measurements. The kapp values for the bare and benzylamino modified electrodes were found to be 1.2 × 10−4 cm.s−1 and 4.9 × 10−6 cm.s−1, respectively. The electrocatalysis of the modified electrodes towards detection of H2O2 gave significant peak current densities and electrocatalytic potentials at −0.28 V and −0.31 V for the MnTAPc and CoTAPc modified electrodes, respectively.
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  • Date Issued: 2015

A retrospective assessment of the Port Alfred linefishery with respect to the changes in the South African fisheries management environment

  • Authors: Donovan, Bruce
  • Date: 2013-07-18
  • Subjects: Fishery management -- South Africa -- Port Alfred , Fisheries -- South Africa -- Port Alfred , South Africa. Marine & Coastal Management , Coastal zone management -- South Africa -- Port Alfred , Fishing -- South Africa -- Port Alfred , Fisheries -- Environmental aspects -- South Africa -- Port Alfred , Fish stock assessment -- South Africa -- Port Alfred , Fishing surveys -- South Africa -- Port Alfred , Marine fishes -- South Africa -- Port Alfred
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5353 , http://hdl.handle.net/10962/d1008298 , Fishery management -- South Africa -- Port Alfred , Fisheries -- South Africa -- Port Alfred , South Africa. Marine & Coastal Management , Coastal zone management -- South Africa -- Port Alfred , Fishing -- South Africa -- Port Alfred , Fisheries -- Environmental aspects -- South Africa -- Port Alfred , Fish stock assessment -- South Africa -- Port Alfred , Fishing surveys -- South Africa -- Port Alfred , Marine fishes -- South Africa -- Port Alfred
  • Description: Since the study on the Port Alfred/Kenton-on-Sea/Boknes linefishery by Hecht and Tilney (1989) there have been substantive changes to the linefish management environment in South Africa. Using the Port Alfred linefishery as a model, the aim of this study was to evaluate the effectiveness of the linefish management regulations that were implemented by Marine and Coastal Management (MCM) since 1992, and to assess the behaviour and 'status' of the fishery in response to these changes. Changes to both the licensing structure and catch regulations have had a significant effect on the functioning of many aspects of the Port Alfred linefishery (fishing effort, catch composition, cpue) as well as on the structure of the fishery and its socio-economic profile. Overall commercial cpue decreased from 1985 to 1998. Since 1998 there has been a significant increase in cpue (from 2.3 Kg.fisher⁻¹ hour⁻¹ to a peak of 4.8 Kg.fisher⁻¹.hour⁻¹ in 2005. This was attributed to good catches of geelbek, particularly in 2005, 2007 and 2008 (during these years geelbek contributed an average of 35% to the total landings in comparison to a mean contribution of II % between 1985 and 2004). However, size spectra analysis suggests that the increase in overall cpue since 1998 misrepresents the actual status of the fishery. If geelbek is excluded from the analysis on the grounds that it is the only species in the fishery that is highly migratory, susceptible to recruitment fluctuations and it does not contribute to the catches on a year round basis, then the results suggest that the fishery is still in a declining phase despite the 80% reduction in commercial effort and numerous stricter catch regulations (e.g. size/bag limits). Furthermore, the cpue of silver kob, which has been the "mainstay" species of the fishery, has consistently declined over the last 23 year period (from 1.69 Kg.fisher⁻1 .hour1 in 1986 to 0.86 Kg.fisher⁻1.hour⁻1in 2007). The substantial reduction in commercial effort in the fishery from 33 vessels in 2001 to 13 in 2002 resulted in a shift from commercial to recreational fishing. The number of active commercial vessels in Port Alfred alone decreased from 29 in 1989 (Hecht 1993) to four in 2008. During the same timeframe, the number of regularly active recreational vessels had almost doubled (16 in 1989 to 26 in 2008). Despite the greater number of recreational boats in the fishery they only landed approximately half the average yearly tonnage of the commercial vessels (21,5 and 44,7 tonnes,annum-I , respectively) between 2006 and 2008, This was ascribed to the differences in catch regulations for the two sectors, Furthermore, it was speculated that increasing operating costs and narrowing profit margins have contributed to lower levels of compliance in both the commercial and recreational sectors since 2006, For example, 16% of silver kob landed during 2006-08 were under the minimum size, Despite the changes made to the regulations since 1998 and the 60,6% reduction In legislated commercial effort in the fishery between 2001 and 2002 it was concluded that the fishery has continued to decline, Except for the good recruitment of geelbek (which may be due to regulatory changes made in 1992) the changes in the management environment have had no measurable positive effect on this fishery, It is recommended that commercial effort should not be allowed to increase beyond the current number of active boats, that there should be an area restriction on all commerciallinefish vessels, that the current recreational bag limit for silver kob should be re-assessed, there should also be a concerted and nationally funded effort to educate recreational anglers about the merits of catch and release, and the frequency of catch inspections of both sectors should be increased, , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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Becoming African: debating post-apartheid white South African identities

  • Authors: Matthews, Sally
  • Date: 2011
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/142409 , vital:38077 , DOI: 10.1080/14725843.2011.530440
  • Description: The post-apartheid era necessitates the rethinking of white identities in South Africa. One way in which some white South Africans are seeking to redefine themselves is through describing themselves as African. However, claims by white South Africans that they too are Africans have been met with mixed responses from black South Africans. In this article I use contributions to an online university students' forum to explore ways in which some white South Africans are embracing an African identity and to consider ways in which some black South Africans are responding to white South Africans' shifting identities. I use contributions to this forum as a starting point to think about the possibilities and limitations that the embracing of an African identity has for the development of what Frankenberg calls ‘anti-racist forms of whiteness’ among white South Africans.
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  • Date Issued: 2011

Developing visual images for communicating information aboutantiretroviral side effects to a low-literate population:

  • Authors: Dowse, Roslind , Ramela, Thato , Barford, Kirsty-Lee , Browne, Sara H
  • Date: 2011
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/156769 , vital:40048 , https://doi.org/10.2989/16085906.2010.530172
  • Description: The side effects of antiretroviral (ARV) therapy are linked to altered quality of life and adherence. Poor adherence has also been associated with low health-literacy skills, with an uninformed patient more likely to make ARV-related decisions that compromise the efficacy of the treatment. Low literacy skills disempower patients in interactions with healthcare providers and preclude the use of existing written patient information materials, which are generally written at a high reading level. Visual images or pictograms used as a counselling tool or included in patient information leaflets have been shown to improve patients’ knowledge, particularly in low-literate groups. The objective of this study was to design visuals or pictograms illustrating various ARV side effects and to evaluate them in a low-literate South African Xhosa population. Core images were generated either from a design workshop or from posed photos or images from textbooks. The research team worked closely with a graphic artist. Initial versions of the images were discussed and assessed in group discussions, and then modified and eventually evaluated quantitatively in individual interviews with 40 participants who each had a maximum of 10 years of schooling.
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  • Date Issued: 2011

Effect of turbidity on the foraging success of Glossogobius callidus (Teleostei: Gobiidae)

  • Authors: Parkinson, Matthew C , Booth, Anthony J
  • Date: 2011
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/124375 , vital:35600 , https://doi.org/10.2989/16085914.2011.589120
  • Description: Particles suspended in water attenuate the light that passes through it via absorption or scattering (Utne-Palm 2002). For example, whereas algae absorb specific wavelengths of light necessary for photosynthesis, inorganic suspensoids tend to scatter light (Radke and Gaupisch 2005). This results in lowered ambient light levels and reduces the visual acuity of aquatic organisms. From a fish’s perspective, an increase in water turbidity has the potential to alter visually-mediated reproductive behaviours (Järvenpää and Lindström 2004), predator avoidance (Meager et al. 2006) and foraging success negatively (Utne-Palm 2002, Rowe et al. 2003, Sweka and Hartman 2003, Stuart-Smith et al. 2004). The foraging success of various fish species was affected by increased turbidity through decreasing predator–prey encounter rates (Sweka and Hartman 2003) and through decreasing visual acuity whereby the distance at which prey are visually detected is reduced (Utne-Palm 2002).
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  • Date Issued: 2011

Know your rights! A basic guide for domestic workers in South Africa

  • Authors: Labour Research Service (LRS)
  • Date: 2010-06
  • Subjects: Household employees -- Legal status, laws, etc. -- South Africa , Household employees -- Employment -- South Africa , Labour contract -- South Africa
  • Language: English
  • Type: book , text
  • Identifier: http://hdl.handle.net/10962/60041 , vital:27725
  • Description: The demand for domestic services has increased globally during the last two decades and today domestic workers constitute a large portion of the workforce, especially in developing countries. Yet domestic work is undervalued and poorly regulated, and many domestic workers are underpaid and unprotected. This has been recognised by international organisations, such as the International Labour Organisation (ILO). The struggle of domestic workers has lead to improvements to their rights and conditions in many countries. Yet working conditions and wages remain poor in many countries, including South Africa. This booklet sheds light on this problem. There are 888 000 domestic workers in South Africa, which accounts for 7% of total formal employment (Labour Force Survey, May 2010). The vast majority of these workers do not belong to a trade union and do not partake in collective bargaining or are unaware of their rights to bargain and to join trade unions. The South African Domestic Services and Allied Workers Union (SADSAWU) is a trade union for domestic workers in South Africa and campaigns for the improvement of rights and conditions of domestic workers. It recognises that it is not as powerful as it could be and it would have a bigger influence on the legislating authorities if there were more members which were strongly organised. There are numerous difficulties to organise domestic workers, some are related to the education level of the workers and some lies within the nature of the work (many are live-in workers and therefore have no contact with other domestic workers as a natural part of their work). However, SADSAWU has over many years built up a lot of experience and developed a solid vision to build a strong domestic workers movement, and is therefore well placed to fight these difficulties. This booklet also serves as an organising tool for domestic workers. The aim is to raise awareness of the rights of domestic workers and to encourage workers to organise.
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  • Date Issued: 2010-06

"Fit for purpose": towards tracking the quality of university education of entry-level journalists

  • Authors: Berger, Guy
  • Date: 2010
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/159835 , vital:40348 , DOI: 10.1080/02560054.2005.9653329
  • Description: Debate about the extent to which university education should serve industry is an important consideration for institutions of higher learning in a transforming South Africa, and particularly for those teaching would-be journalists. This issue can also be profitably analysed with reference to the current framework of the South African education authorities who argue that the quality of higher education institutions should be measured in terms of their “fit for purpose” to missions aligned to stakeholder interests in the transformation of the country as a whole. This criterion for quality assessment tends to focus on the educative processes within a university, but it can be argued that it ought to extend into the examination of the output consequences of journalism teaching. This would amount to not just fitness for purpose, but also achievement of purpose – and the latter including a creative and critical impact.
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  • Date Issued: 2010

"I don't think it's the whole story!": a case study of the linguistic face management strategies of dyslexic adults

  • Authors: Henderson, Layle
  • Date: 2010
  • Subjects: Dyslexia Case studies Dyslexia -- Social aspects Dyslexia -- Psychological aspects Politeness (Linguistics) Sociolinguistics
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2347 , http://hdl.handle.net/10962/d1002629
  • Description: Dyslexia is primarily a neurobiological disorder and much research has been conducted on this (see for example Coltheart 1996; Shaywitz and Shaywitz 2000 and 2004). However, little has been done which investigates the social construction of dyslexia. Because dyslexia affects reading, writing and spelling to varying degrees, although it may originate from genetic inheritance, it manifests itself in social spheres. Brown and Levinson‟s (1987) Face Theory states that people use strategies to minimise the damage to the positive face of others. My research focuses on how dyslexic individuals use linguistic strategies to minimise potential face-threatening acts or FTAs against themselves and in so doing preserve their own positive face. Using elements of Face Theory and APPRAISAL I constructed a typology reflecting these linguistic face management devices of adults with dyslexia. With this research I hope to contribute to the field in an innovative and meaningful manner through an exploration of the linguistic face management strategies used in the management of positive face.
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  • Date Issued: 2010

"Rape and cable theft on the increase": interrogating Grocott's Mail coverage of rape through participatory action research

"Tell me how you read and I will tell you who you are": children's literature and moral development

  • Authors: Van der Nest, Megan
  • Date: 2010
  • Subjects: Children's literature -- Philosophy Children's literature -- Moral and ethical aspects Children's literature -- History and criticism Literature and morals Ethics in literature Reader-response criticism Moral conditions in literature Literature -- Study and teaching
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2722 , http://hdl.handle.net/10962/d1002852
  • Description: It is a common intuition that we can learn something of moral importance from literature, and one of the ways in which we teach our children about morality is through stories. In selecting books for children to read a primary concern is often the effect that the moral content of the story will have on the morality of the child reader. In this thesis I argue in order to take advantage of the contribution that literature can make to moral development, we need to teach children to read in a particular way. As a basis for this argument I use an account of moral agency that places emphasis on the development of moral skills - the ability to critically assess moral rules and systems, and the capacity to perceive and respond to the particulars of individual situations and to choose the right course of action in each - rather than on any particular kind of moral content. In order to make the most of the contribution that literature can make to the development of these skills, we need to teach children to immerse themselves in the story, rather than focusing on literary criticism. I argue that, contrary to the standard view of literary criticism as the only form of protection against possible negative effects, an immersed reading will help to prevent the child reader from taking any moral claims made in the story out of context, and so provide some measure of protection against possible negative moral effects of the story. Finally I argue that there are certain kinds of stories - recognisable by features that contribute to a high literary quality - that will enrich the experience of an immersed reading, and will therefore make a greater contribution to moral development than others.
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  • Date Issued: 2010

"The secret rapport between photography and philosophy" considering the South African photographic apparatus through Veleko, Rose, Goldblatt, Ractliffe and Mofokeng

  • Authors: Mountain, Michelle Fiona
  • Date: 2010
  • Subjects: Veleko, Nontsikelelo Rose, Tracy Goldblatt, David Ractliffe, Jo 1961- Mofokeng, Santu, 1956- Photographers -- South Africa Photography -- Philosophy Photography -- Social aspects -- South Africa Apartheid in art Documentary photography -- South Africa Space (Art) -- South Africa South Africa Social conditions
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2415 , http://hdl.handle.net/10962/d1002211
  • Description: This thesis is an attempt at understanding South African photography through the lens of Nontsikelelo “Lolo” Veleko, Tracy Rose, David Goldblatt, Jo Ractliffe and Santu Mofokeng. Through the works discussed this thesis intends to unpack photography as a complex medium similar to that of language and text, as well as attempt to understand how exploring South African experiences and spaces through the lens of photography shapes and mediates them. Furthermore it also attempts to understand how these experiences and spaces conversely affect the discourse of photography or at the very least our perception of it. Through these photographers and their works it is hoped that ultimately the interconnected relationship of exchanging codes that takes place between photography and society will be highlighted. The example of connectivity or dialogue I believe exists between the medium of photography and the physical/social and psychological spaces it photographs will be mediated through Deleuze and Guattari‟s conception of “the wasp and the orchid” where “the wasp becomes the orchid, just as the orchid becomes the wasp...an exchanging or capturing of each other‟s codes”. Other theorists I will be looking at include Vilém Flusser, focusing in particular on his book Towards a Philosophy of Photography, as well as Susan Sontag, Roland Barthes and others. The main aims and objectives of this thesis are to understand the veracity of the documentary image and whether or not the image harbours any objective truth, as well as whether truth, if it can truly be said to exist in the world, resides between the camera and the seen world. This dichotomy is further complicated by the matter of subject-hood and technical and philosophical understandings of the camera as an apparatus. At no point do I aim to be conclusive, rather it is hoped that by developing the dynamic tension between the theory and the image world that I will be able to bring fresh insight into the reading of a changing South African condition and the subject position of the photographer in relation to this condition.
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  • Date Issued: 2010

'I won't be squeezed into someone else's frame': Stories of supervisor selection

  • Authors: Harrison, Liz , McKenna, Sioux , Searle, Ruth
  • Date: 2010
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187395 , vital:44629 , xlink:href="https://hdl.handle.net/10520/EJC15100"
  • Description: Using a collection of stories from a group of women who belong to a PhD support group, this article tracks the issue of choosing a supervisor. These women are all academics and therefore had some claim to an "insider" status but as novice researchers they were also "outsiders". Their discussions around how and why they chose their supervisors highlight issues often underplayed or ignored in textbooks on postgraduate supervision. In particular, this article examines issues of knowledge, embodied subjectivity and power by following three questions that arise from the data : whose knowing is important; who should I be, and whose PhD is it?
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  • Date Issued: 2010

'Rich man poor man': inter-household and community factors influencing the use of wild plant resources amongst rural households in South Africa

  • Authors: Cocks, Michelle L , Bangay, Lindsey , Shackleton, Charlie M , Wiersum, K Freerk
  • Date: 2010
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/141211 , vital:37953 , DOI: 10.3843/SusDev.15.3:3
  • Description: Biodiversity is recognised as an integral part of people's daily livelihoods. This study therefore aims to understand the use of NTFPs at an intricate level by determining what role these resources fulfil in six rural villages and 1011 households' livelihoods. It examines how the use of NTFPs are influenced by intra-household variables, such as wealth and gender, and inter-community variables, such as accessibility to the natural resource. The results reveal that approximately 4453 kg of wild material is used annually per household, of which 1598 kg is used for cultural purposes. The influence of vegetation type and differences between villages are statistically more significant than inter-household variables. At an inter-household level, an increase in the financial status of households did not result in a decrease in the use of natural resources, nor in the quantity of material used.
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  • Date Issued: 2010

'Visible hectares, vanishing livelihoods': a case of the fast track land reform and resettlement programme in Southern Matabeleland- Zimbabwe

  • Authors: Mabhena, Clifford
  • Date: 2010
  • Subjects: Sustainable development -- Zimbabwe , Rural poor -- Zimbabwe , Rural development -- Zimbabwe , Land tenure -- Zimbabwe , Land reform beneficiaries -- Zimbabwe , Livestock -- Breeding -- Zimbabwe , Land settlement -- Zimbabwe
  • Language: English
  • Type: Thesis , Doctoral , D Soc Sc
  • Identifier: vital:11423 , http://hdl.handle.net/10353/d1001193 , Sustainable development -- Zimbabwe , Rural poor -- Zimbabwe , Rural development -- Zimbabwe , Land tenure -- Zimbabwe , Land reform beneficiaries -- Zimbabwe , Livestock -- Breeding -- Zimbabwe , Land settlement -- Zimbabwe
  • Description: Land reform has been going on in Zimbabwe since the state attained independence from Britain in 1980 as a way of enhancing agrarian livelihoods for the formerly marginalized people. This study argues that, the Land Reform Programme in Southern Matabeleland rather than enhancing agrarian livelihoods, well established livelihoods have actually been drastically reduced. This has been exacerbated by the state programme of land re-distribution that prescribes a „one size fits all‟ model. Yet this is contrary to the thinking in development discourse that equitable land distribution increases rural livelihoods. As a way of gathering data this study utilized ethnography and case study methodologies. I spent two years interacting and interviewing purposively selected new resettles, communal residents, migrant workers and gold panners in this region. Results from this study confirm that, land reform has greatly reduced livelihoods, particularly agrarian livelihoods. Also, this research has found out that, the majority of residents now depend on off-farm livelihoods such as gold panning and migration to neighbouring South Africa. This thesis therefore concludes that, despite a massive expropriation of former commercial farms, people of Southern Matabeleland have not benefitted much as the village settlements (A1) and the small size farms (A2) have not received support from this live-stocking community. People in this region pin their hopes on livestock rearing to sustain their livelihoods and this study therefore recommends that, any agrarian transformation programmes should address the issues that promote livestock rearing
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  • Date Issued: 2010

25 years of training doctors at WSU: how have we responded to the 1983 UNITRA Council Guidelines?

  • Authors: Kwizera, E N
  • Date: 2010
  • Subjects: Medical education -- South Africa -- Eastern Cape Clinical medical -- Teaching and learning
  • Language: English
  • Type: text , Lectures
  • Identifier: http://hdl.handle.net/11260/801 , vital:29826
  • Description: More importantly, Mr VC, Sir, some relatively more recent improvisations have been in the roles I have played in the development, implementation, and evaluation of the Problem-based, and Community-based MB ChB curriculum at the then UNITRA (and now WSU) from 1989 to date4-33; particularly my successful introduction of ‘one tutor per tutorial group’ in our programme8,10,12,14. As I will elaborate in due course, one of the secrets of our success as a medical school has been the adaptation of ideas and practices from diverse parts of the world to make them fit in our settings; and needless to say, this has involved a lot of improvisation.
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  • Date Issued: 2010

31P NMR kinetic study of the tandem cleavage of phosphonate esters by bromotrimethylsilane

  • Authors: Conibear, Anne C , Lobb, Kevin A , Kaye, Perry T
  • Date: 2010
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/449304 , vital:74810 , xlink:href="https://doi.org/10.1016/j.tet.2010.08.058"
  • Description: 1H and 31P NMR methods have been used to access rate constants and activation parameters for each of the consecutive second-order silylation reactions involved in the overall transformation (1a→3a→4a), while computational optimisation of the rate constants obtained from the initial, linear phase of each reaction has permitted an excellent fit with the experimental data for the entire course of the reaction.
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  • Date Issued: 2010

A biochemical study of the antidiabetic and anticogulant effects of Tulbaghia Violacea

  • Authors: Davison, Candice
  • Date: 2010
  • Subjects: Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10311 , http://hdl.handle.net/10948/1523 , Medicinal plants -- South Africa , Diabetes -- Alternative treatment -- South Africa , Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Plants -- Analysis
  • Description: Secondary metabolites derived from plants, especially those used by traditional healers, are at the forefront of new drug development in combating diseases such as cancer and diabetes. Garlic is employed in indigenous medicine all over the world for the treatment of a variety of diseases. Dietary garlic has been recognized for its beneficial health effects. In particular, garlic consumption has been correlated with (i) reduction of risk factors for cardiovascular diseases and cancer, (ii) stimulation of immune function, (iii) enhanced detoxification of foreign compounds, (iv) hepatoprotection, (v) antimicrobial effects, (vi) antioxidant effects, and most importantly (vii) its hypoglycemic and anticoagulant properties. Due to these beneficial properties, garlic and its closely related genera which includes Tulbaghia violacea, may be useful as coadjuvant therapy in the treatment of type 2 diabetes and some of its physiological complications. The aim of this study was to determine if T. violacea has antidiabetic and anticoagulant properties. This was performed in vitro using both aqueous and organic extracts of the roots, leaves and bulbs. An organic extract was able to improve glucose-stimulated insulin secretion (GSIS) in INS-1 pancreatic β-cells and glucose uptake in Chang liver cells. The BO extract had no effect on the glucose uptake in 3T3-L1 an adipose cell line and reduced glucose utilisation in C2C12, a skeletal muscle cell line. Some of the properties displayed by T. violacea in this study are consistent with those found in similar studies with garlic extracts. It was observed that the BO extract increased the membrane potential and Glut-2 expression in INS-1 cells cultured at hyperglycemic levels, however, at normoglycemic levels a reduction was observed. The oxygen consumption increased at both glycemic levels due to treatment with the BO extract. Platelets were exposed to the extracts to determine their effects upon platelet aggregation, adhesion and protein secretion. Since the BO extract displayed the highest potential at inhibiting platelet aggregation and adhesion. A rat model was used in ex vivo studies to determine if the extract exhibited the same effect in a physiological model. It was noted that the BO extract exhibited a higher degree of inhibition on platelet aggregation and adhesion than the positive control, aspirin. The BO extract reduced clotting times in the prothrombin time (PT) test, but prolonged the clotting time in the actived partial thromboplastin time (APTT) assay in the ex vivo model; however, it had no affect on these clotting assays in the in vitro model using human blood. The BO extract increased the D-dimer and Fibrinogen-C levels in the in vitro model, but had no effect on the D-dimer concentrations and lowered the Fibrinogen-C levels in the ex vivo model. The active compounds in the extract remain to be elucidated.
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  • Date Issued: 2010

A bioinorganic investigation of some metal complexes of the Schiff base, N,N'-bis(3-methoxysalicylaldimine)propan-2-ol

  • Authors: Mopp, Estelle
  • Date: 2010 , 2012-04-13
  • Subjects: Schiff bases , Bioinorganic chemistry , Metal complexes , Transition metal complexes , Transition metals , Cancer -- Chemotherapy , Ligands -- Toxicity , Antineoplastic agents
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4413 , http://hdl.handle.net/10962/d1006768 , Schiff bases , Bioinorganic chemistry , Metal complexes , Transition metal complexes , Transition metals , Cancer -- Chemotherapy , Ligands -- Toxicity , Antineoplastic agents
  • Description: This thesis includes the synthesis, characterisation, antioxidant and antimicrobial activities of Cu(II)-, Co(II)- and Co(III) complexes with N,N'-bis(3- methoxysalicylaldimine)propan-2-ol, 2-OH-oVANPN. The Schiff base ligand, 2-OHoVANPN, is derived from o-vanillin and 1,3-diaminopropan-2-ol. The o-vanillin condensed with 1,3-diaminopropan-2-ol in a 2:1 molar ratio yields this potential tetraor pentadentate ligand. The complexes synthesized are tetra (or penta or hexa) coordinated. Formation of the complexes is symbolized as follows:- MX₂ + 2-OH-oVANPN (2:1) -> [M(2-OH-oVANPN)Xn] + HnX MX₂ + 2-OH-oVANPN (2:1) -> [Mn(2-OH-oVANPN)OH] + H₂X₂ MX₂ + (o-vanillin : diaminopropanol) (1:1) -> [M(1:1)X₂] MX₂ + (o-vanillin : diaminopropanol) (1:1) -> [M₃(1:1)X₄] M = Cu(II), Co(II) or Co(III); X = Cl; n = 1, 2. Their structural features have been deduced from their elemental analytical data, IR spectral data, and electronic spectral data. With the exception of {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆}(A4), the Cu(II) complexes were monomeric with 2-OH-oVANPN acting as a tetradentate ligand. A binuclear Co(II) complex, [Co₂(C₁₉H₁₉N₂O₅)(OH)] (B1), was synthesised and the rest of the Co(II) and Co(III) complexes were monomeric with chloride ions coordinating to the metal centre in some cases. Electronic data suggest that the cobalt(II) complexes have octahedral geometries and the copper(II) complexes have square planar structures – Co(III) is likely to be octahedral. Thermal analyses, which included the copper-block-method for determining sublimation temperatures, revealed that some copper(II) and cobalt(II) complexes are hygroscopic and sublime at 200 °C and below. DSC analyses of the Cu(II) complexes gave exotherms around 300 °C for complexes K[Cu(C₁₉H₂₀N₂O₅)(OH)]·2H₂O (A1) and [Cu(C₁₁H15N₂O₃)(Cl)₂]·2H₂O (A2) and above 400 °C for [Cu(C₁₁H₁₆N₂O₃)(Cl)₂] (A3) and {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆} (A4). Antioxidant studies were carried out against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·). The cobalt(II) complex, [Co₂(C₁₉H₁₉N₂O₅)(OH)] (B1), which was synthesized in the presence of KOH, had no antioxidant activity, whilst the other cobalt(II) complexes, [Co(C₁₇H₁₇N₂O₅(Cl))]·1½H₂O (B2), [Co(C₁₉H₂₂N₂O₅) (Cl)₂]·5½H₂O (B3) and [Co(C₁₉H₂₂N₂O₅)(Cl)₂]·5½H₂O (B4), which were synthesised in the absence of KOH, demonstrated antioxidant activity. The latter complexes are candidates for cancer cell line testing, while [Cu(C₁₁H₁₆N₂O₃)(Cl)₂] (A3), {Cu₃(C₁₁H₁₄N₂O₃)(Cl)₄(H₂O)₆} (A4), [Co(C₁₉H₂₁N₂O₅)(Cl)₂ ]·5H₂O (C2) and [Co(C₁₉H₂₀N₂O₅)(Cl)]·3H₂O (C3) may show anticancer activity through possible hydrolysis products. Most of the complexes synthesized displayed antimicrobial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans. The results indicated that complexes [Cu(C₁₁H₁₆N₂O₃)(Cl)₂](A3), [Co(C₁₉H₂₂N₂O₅)(Cl)₂]·5½H₂O (B3) and [Co(C₁₉H₂₁N₂O₅)(Cl)₂ ]·5H₂O (C2) are active against the Gram-negative Ps. aeruginosa and that the ligand, 2-OH-oVANPN, did not have any activity. The same trend was observed with 2-OH-oVANPN, {Cu₃(C₁₁H₁₄N₂O₃)(Cl)4(H₂O)₆} (A4) and [Co(C₁₉H₂₀N₂O₅)(Cl)]·3H₂O (C3) against the Gram-positive S. aureus. As for activity against E. coli and C. albicans, some complexes showed more activity than the ligand. There is an observed trend here that the metal complexes are more active (toxic) than the corresponding ligand, which is in agreement with Tweedy’s chelation theory.
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  • Date Issued: 2010

A case study : exploring a DVD driven approach for teaching and learning mathematics, at secondary school level, with a framework of blended learning

  • Authors: Padayachee, Pragashni
  • Date: 2010
  • Subjects: Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10504 , http://hdl.handle.net/10948/1384 , Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
  • Description: Post-apartheid South Africa is witnessing an education crisis of significant proportions. The new outcomes-based education system has failed to deliver and universities are suffering the consequences of under-preparation of learners for tertiary studies especially in mathematics. The educator corps is lacking and it has become common practice for universities to deploy augmented programmes in mathematics for secondary school learners in the surrounding areas. This thesis describes a particular approach of blended learning, devised for the Incubator School Project (ISP), an initiative of the Nelson Mandela Metropolitan University (NMMU) in the Eastern Cape of South Africa. The defining feature of this blended approach is that it incorporates DVD technology, which offers an affordable and accessible option for the particular group of learners and the schools they attend. The thesis poses the research question: How did the use of the DVD approach within a blended learning environment support the learning of mathematics? This case study explores the particular blended approach and reports six fold on the approach – qualitatively based firstly on a questionnaire completed by learners and secondly on interviews of learners, thirdly on the facilitators reports, fourthly quantitatively on learner performance before and after the intervention. Fifthly six schools are used as a case study where the mathematics performance of the learners who participated in the ISP is compared to those who did not participate in the ISP. Finally the scope of blending of this model is evaluated by means of a radar chart, adapted from an existing radar measure. This research revealed that using the DVD approach within a blended learning environment did lead to an improvement in learners perceptions about mathematics, an improvement in the manner in which they learned mathematics, an extension in their mathematics knowledge and provided learners with a supportive environment in which to learn mathematics. The elements which supported learning in this approach are presented. The findings of the study suggest that this approach impacted favourably on the mathematics learning and enhanced the mathematics learning and performance of these learners. Recommendations are offered for practice, teachers and schools and for further research possibilities.
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  • Date Issued: 2010

A chemo-enzymatic process for the production of beta-thymidine, a key intermediate in antiretrovirol manufacture

  • Authors: Gordon, Gregory Ernest Robert
  • Date: 2010
  • Subjects: HIV infections -- Treatment -- South Africa , HIV infections -- South Africa -- Prevention , Antiretroviral agents
  • Language: English
  • Type: Thesis , Doctoral , DTech
  • Identifier: vital:10423 , http://hdl.handle.net/10948/d1016217
  • Description: The socio-economic impact of HIV/AIDS on South Africa has resulted in lower gross domestic product, loss of skills in key sectors such as education, and increased health-care costs in providing access to treatment. Currently active pharmaceutical ingredients (API’s) such as stavudine (d4T) and azidothymidine (AZT) are imported from India and China, while formulation is conducted locally. A strategy was initiated between CSIR Biosciences and LIFElab under the auspices of Arvir Technologies to investigate the feasibility of local antiretroviral manufacture (d4T and AZT) or the manufacture of a key intermediate such as β- thymidine (dT). Several advantages associated with successful implementation of this strategy include ensuring a local supply of API’s, thus reducing reliance on procurement from foreign sources and reducing the effect of foreign exchange rate fluctuations on providing cost effective access to treatment. A local supply source would also reduce the imports and thus aid the balance of payments deficit, and in addition to this, provide stimulus in the local pharmaceutical manufacturing industry (which has been in decline for several decades), resulting in increased skills and employment opportunities. This thesis describes the development of a superior chemo-enzymatic process for the production of β-thymidine (72 percent yield, prior to isolation), a key intermediate in the preparation of anti-retrovirals. Alternative processes based purely on chemical or bioprocess transformations to prepare either 5-methyluridine (5-MU) or dT suffer from several disadvantages: lengthy transformations due to protection/deprotection strategies, low selectivties and product yields (30 percent in the chemical process) and isolation of the product from dilute process streams requiring the use of large uneconomical reactors (bioprocesss). This contributes significantly to the cost of d4T and AZT manufacture. Our novel chemoenzymatic process comprises of a biocatalytic reaction for the production of 5-MU, with subsequent chemical transformation into dT (3 steps) negating and circumventing the limitations of the chemical or bioprocess routes. During the course of this project development, the β-thymidine selling price declined from 175 $/kg (2005) to 100 $/kg (2008). However, the process described in this work is still competitive based on the current β- thymidine selling price of 100 $/kg. The process economics show that with further optimization and increasing the isolated dT yield from 70 percent to 90 percent, the variable cost decreases from 136 $/kg to 110 $/kg. The increase in isolated yield is highly probable, based on solubility data of β-thymidine. The decrease in β-thymidine selling price and technological improvement in dT manufacture should translate into lower API manufacture costs and more cost effective access to treatment. Our novel biocatalytic process producing 5-MU uses a coupled enzyme system employing PNP, Purine Nucleoside Phosphorylase and PyNP, Pyrimidine Nucleoside Phosphorylase. The overall transglycosylation reaction may be decoupled into the phosphorolysis reaction (PNP) and synthesis reaction (PyNP). During the phosphorolysis reaction, guanosine is converted into guanine and ribose-1-phosphate (R-1-P) in the presence of PNP enzyme. The reaction intermediate R-1-P is then coupled to thymine in the presence of PyNP enzyme during the synthesis reaction, producing 5-MU. The process was scaled up from lab-scale to bench-scale (10 - 20 L) and demonstrated to be robust and reproducible. This is evident from the average guanosine conversion (94.7 percent ± 2.03) and 5-MU yield (88.2 percent ± 6.21) and mole balance (104 percent ± 7.61) which were obtained at bench-scale (3 replicates, 10 L). The reaction was carried out at reactor productivities of between 7 – 11 g.L-1.h-1. The integration of the biocatalytic process and chemical processes was successfully carried out, showing that 5-MU produced using our novel biocatalytic process behaved similarly to commercially available 5- MU (ex. Dayang Chemicals, China). A PCT patent application (Ref. No. P44422PC01) on this chemo-enzymatic process has been filed and currently public private partnerships are being explored through Arvir Technologies to evaluate and validate this technology at one ton scale.
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  • Date Issued: 2010
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