The variation of conditions of employment
- Authors: Horo, Lindile
- Date: 2002
- Subjects: Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11043 , http://hdl.handle.net/10948/282 , Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Description: This paper seeks to bring clarity to a number of issues that arise from a process resulting from the unilateral variation of terms and conditions of employment and the conflict management and dispute resolution processes. The variation of employment terms particularly when it is driven by one party to the employment relationship can cause instability, insecurity, confusion and uncertainty to the parties involved. The nature of work is not constant and therefore changes are inevitable. This then has an effect of bringing disorder not only to the employer-employee relationship but also to the labour relations balance. In many instances and depending on whether it is the employer or employee who propagates the changes, the reasons to alter the conditions are different. Employers usually cite operational or economic reasons that are meant for the survival of the business as the need to make the changes. From the employees’ side the changes are necessitated by reasons aimed at a move from protecting the favourable employment conditions already acquired to improving them or attaining more. In the event that the parties to the employment relationship do not agree to the changes proposed and implemented, a dispute usually arises. This results from the failure of a consultation process, negotiations, persuasion or collective bargaining in general. In essence such a dispute arises from absence of consent to the changes. The failure of a bargaining system requires the process to assume a new nature. The dispute resolution systems and the conflict management systems follow as both the appropriate and necessary steps. The bargaining power together with the intervention of the third party is at the centre of this phase. The parties, depending on the nature of the dispute, the conditions that iv are changed and who are affected by the changes, have choices on what dispute resolution mechanisms to employ. The choice made has a huge impact on both the outcome required in the form of recourse, how the dispute will be resolved or how the conflict will be managed. There is legislative intervention with regards to the resolution of the conflictual scenarios that arise from disputes on unilateral variation of terms and conditions of employment. There are also non-statutory measures available to the parties. The choices are vast as to when can the variation take place, the reasons for the changes, the parties involved, the possible dispute resolution mechanisms, what can be varied and whether the unilateral implementation can be viewed as fair.
- Full Text:
- 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.
- Full Text:
- Date Issued: 2002
Thermal and photostability studies of furosemide and its cyclodextrin mixtures
- Authors: Melane, Babalwa Blossom
- Date: 2002 , 2013-05-16
- Subjects: Furosemide , Furosemide -- Stability
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4440 , http://hdl.handle.net/10962/d1007625 , Furosemide , Furosemide -- Stability
- Description: Furosemide (Lasix®), abbreviated as FR and also known as frusemide, is a drug used for renal problems and treatment of cardiac edema. Various polymorphic forms of furosemide, dependent upon the method of preparation and thermal treatment, have been reported. The main thermal decomposition product of furosemide has been identified as saluamine. The dissolution properties of furosemide have also been reported to be improved by complexation with beta-cyclodextrin. Photostabilities of the different crystal forms have been studied. Differential scanning calorimetry (DSC) and thermogravimetry (TG) have been used to examine the thermal behaviour of furosemide itself and of its physical and kneaded mixtures with betacyclodextrin (BCD) and gamma-cyclodextrin (GCD). There is strong evidence from DSC that complex formation between FR and GCD occurs. This is supported by IR and XRD data. Decreases in the intensity and broadening of the characteristic carbonyl (1660 cm'l) and amine (1588 cm⁻¹) bands in the kneaded mixture, compared to the physical mixture, were observed with IR. X-ray diffraction results for the 1:3 molar ratio FR/GCD kneaded mixture showed a halo diffraction pattern characteristic. of an amorphous solid and did not resemble patterns from the drug, or the gamma, cyclodextrin, or the physical mixture. Photostability studies have been conducted on solid furosemide and its mixtures with GCD or BCD. An HPLC method was developed to determine the amount of drug remaining after exposure and the presence of any degradants. Results indicated that about 10% degradation of the drug occurred during exposure for 16 hours at 550 W/m², with the appearance of polar degradants. Although IR and DSC results for the 1:3 molar ratio FR/GCD kneaded mixture showed a probable strong interaction between FR and GCD, the photostability of FR was decreased. The 1 :3 molar ratio FR/BCD kneaded mixture showed less photo-degradation than the 1:3 molar ratio FR/GCD mixture under similar conditions, suggesting that inclusion of the drug molecule (FR) is different in the two cyclodextrins.
- Full Text:
- Date Issued: 2002
Thermophilic lignin degrading enzymes from actinomycetes for biotechnological applications
- Authors: Mhlanga, Chido Yvonne Lois
- Date: 2002 , 2013-05-16
- Subjects: Actinomycetales -- Biotechnology , Lignin
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4085 , http://hdl.handle.net/10962/d1007628 , Actinomycetales -- Biotechnology , Lignin
- Description: Phenolic residues which accumulate in the environment as a result of agro-industrial practices has resulted in the need to find and use Eco-Friendly techniques, rather than the traditional methods of burning or burying this kind of waste. Bioremediation and bioconversion are attractive alternatives using whole cell or enzyme-based systems. The aims of this project were to isolate and uses thermophilic Actinomycetes, which produce thermo-tolerant oxidoreductase enzymes, which can be used to bioconvert a model industrial phenolic waste commonly genersated in the wine-making industry of South Africa. Current research in bioconversion and bioremediation focuses on mesophilic microbes in that their enzymes can catalyse reactions at higher temperatures without affecting its activity and lower contamination levels. Three novel Actinomycete isolates were isolated (RU-A0l , RU-A03 and RU-A06) from a compost site and characterized using a combination of conventional identification techniques and 16S rDNA methodology to identity the three isolates. All three isolates belong to the Streptomyces clade. In addition, five known Actinomycetes were selected from an internation culture collection and also screened for oxidoreductase activity in comparision to the three novel isolates. Although the five isolates were selected based on their ability to produce oxidoreductase enzymes, unexpectedly, no activity was detected. Screening assays for peroxidase, polyphenol oxidase and laccase on RU-AO 1, RU-A03 and RU-A06, showed that all three isolated produced peroxidases and peroxidases but no laccase. Substrate specificity studies revealed that the most suitable substrates to determine peroxidase and polyphenol oxidase activity on these isolates were catechol for polyphenol oxidase, 2,4-dichlorophenol for peroxidases and veratryl alcohol for lignin peroxidases. Previous studies have indicated that peroxidases and polyphenol oxidases are produced in Actinomycetes during the primary stage of growth. This was the case with RU-AOI , RU-A03 and RU-A06. Growth rates were higher that other Actinomycetes, with maxImum biomass being reached at 36 hours for the isolates RU-AOI and RU-A06 and 48 hours for isolate RUA03. pH studies showed that the three isolates were adaptable and could grow over a broad pH range. Catabolism studies of phenolic model compounds showed that the three isolates were capable of catabolizing the model phenolic compounds within a period of 24 hours. Further studies were carried out to determine the effect of these microbes and their enzymes in whole cell and enzyme-based systems on a model phenolic waste, graoe waste consisting of compressed grape skins, pips and stalks. Whole cell studies showed that the isolates were capable of bioconverting the waste at a maximum concentration of 30% grape waste (vol:vol). Peroxidase and polyphenol oxidase activity increased indicating induction of these enzymes in the presence of phenolic compounds, with a maximum increase of up to 15.9 fold increase in extracellular lignin peroxidase activity in RU-AO1. HPLC and phenolic determination assays indicated that bioconversion of the phenolic grape waste had occurred in the presence of the three isolates. Attempts were made to isolate and identify a peroxidase or phenol oxidase gene from one the isolates. As bacteria, Actinomycetes are amendable to gene manipulation making them suitable candidates for methods such as site directed evolution in comparison to fungi. Two clones were selected for sequencing based on positive activity results when assayed for peroxidase activity. However the resultant sequences did not identify a functional gene sequence. Southern Blotting was then carried out to determine the nature of the peroxidase gene. Previous studies have been focused on the catalase-peroxidase gene (CalC gene) found Actinomycetes and other bacteria. A probe was developed from the CalC gene. No hybridization occurred with any of the enzyme restricted DNA from the three isolates. The implications of these results are that the peroxidase genets in the three isolates are in fact lignin peroxidase in nature. This project has the potential in the bioconversion of phenolic wastes and is the first description of the use of thermophilic Actinomycetes in the bioconversion of an industrial phenolic waste.
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- Date Issued: 2002
Title not specified
- Authors: Venda men and boys , Tracey, Andrew T N
- Date: 2002
- Subjects: Venda --(African people) , Folk Music , Mbira , Sub-Saharan African music , Africa South Africa Venda f-sa
- Language: Venda
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/112161 , vital:33554 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC126b-01
- Description: Venda traditional music with Mbila Mutondo accompaniment
- Full Text: false
- Date Issued: 2002
Towards a broader socio-ecological education : a case study of school based curricular reform
- Authors: Cimma, Gary Martin
- Date: 2002
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:20973 , http://hdl.handle.net/10962/5763
- Description: This work documents and analyses an action research project that the researcher undertook in conjunction with colleagues at an independent Catholic high school in Johannesburg. The main objective was to try to expand the existing curriculum in operation at the time of starting the research to one, which was more socio-ecologically sensitive. One of the key references during the action research was the recently drafted ‘Vision Statement’ document, which detailed the educational ideals of the school. Some of the key findings that emerged as the research proceeded, were that the levels of socio-ecological sensitivity displayed by the learners were influenced by the backgrounds from which they came, and that these background environments were often not comfortable with the changes taking place in the educational and greater South African environments. The Participatory Action Research mode of research which was used proved to be problematic in that only a handful of the educators actually got involved in participating in the project. The failure of many of educators to get involved was, in the opinion of the researcher, due to their lack of understanding how important the development of social and ecological sensitivity are to the necessary change capacity required in present day South African society. The need to be involved in the ongoing development of curriculum as required by Curriculum 2005 as a form of Outcomes Based Education was also problematic as some educators were not familiar with their role in this regard. The limited time-span of the research was also a limiting factor as the development of a socio-ecologically sensitive curriculum required changes in some fundamental attitudes and approaches to education and the environment.
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- Date Issued: 2002
Towards the performer-creator in contemporary mime, with specific reference to the physical theatre of Andrew Buckland, 1988-2000
- Authors: Murray, Robert Ian
- Date: 2002
- Subjects: Buckland, Andrew , Mime , Mimes -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2158 , http://hdl.handle.net/10962/d1007720
- Description: Part one of this thesis investigates the conceptualisation of the performer-creator and its relevance in late twentieth century physical performance by examining some of the theoretical, but mainly artistic, traditions that suggest a movement towards this. Chapter one tackles the question of definition, linking mime within a wider physical theatre phenomenon. Chapter two looks at the importance of mime training for contemporary performance. This requires a focus on selected theatre practitioners who have significantly advanced the development of mime training and performance during the twentieth century. Chapter three examines the issue of silence in mime and questions a potential liberation of the word and language in contemporary performance and consequently how this affects the role of the performer, particularly in South Africa. Chapter four investigates the figure of the theatrical clown and how this late twentieth century development is playing an increasingly important role in contemporary performance. Chapter five then wraps up part one by pulling the preceding chapters together and thereby providing a working conceptualisation of the performer-creator, locating it within an overall appreciation of contemporary mime. Part two then tests the notion of the performer-creator by focussing on a case study through the investigation of Andrew Buckland to develop this idea. Andrew Buckland, and his work under the ethos of Mouthpeace from 1988-2000, provides a clear and unique example of this movement in contemporary South African performance. Trained as an actor and in classical illusion-based mime technique, as well as many dance forms such as ballet, contemporary and jazz, he has virtually single-handedly created and shaped a particular performance trend that is in line with contemporary international trends but retains a distinctive South African flavour. There is no space to attempt a definitive or exhaustive examination of his works, and nor is the intent to do so; rather, the aim is to draw from his work their essences that reveal his development as an artist: as both a creator and a performer.
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- Date Issued: 2002
Traditional leaders in post-1996 South Africa, with particular reference to the Eastern Cape
- Authors: De Sas Kropiwnicki, Zosa Olenka
- Date: 2002
- Subjects: Tribal government -- South Africa -- Eastern Cape , Political leadership -- South Africa -- Eastern Cape , South Africa -- Politics and government
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2857 , http://hdl.handle.net/10962/d1007479 , Tribal government -- South Africa -- Eastern Cape , Political leadership -- South Africa -- Eastern Cape , South Africa -- Politics and government
- Description: The failure of democracy in Africa can be partially attributed to the Eurocentric assumptions that belie Western recommendations for Africa. This thesis focuses on the failure of the modernisation school to account for the resiliency of tradition in the modern African state, which is described by Sklar (1991) as amounting to a form of 'mixed government', combining the traditional with the modern to create a uniquely African form of governance. This notion of a 'mixed government' is addressed from the vantage point of traditional leaders in the Eastern Cape. It maps the vacillating relationship between the chiefs, the people and the government through colonialism, Apartheid and democratisation. It concludes that although the Eastern Cape provincial government has subordinated the chiefs, this does not signify a victory for modernity over tradition because the chiefs are not a spent force. History has shown that when the government fails to act in the interests of the people, they seek an alternative authority namely, the chiefs. The ANC government's centralising tendencies have negative implications for democracy and consequently for the people. This opens up space for the chiefs to assert themselves provided they play an active role in furthering democracy, development and modernisation in the interests of the people. Hence, although ' mixed' government in the post-1996 South Africa is currently on the ANC's terms, traditional leaders may someday play a vital role in the modern democratic state.
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- Date Issued: 2002
Tshikona
- Authors: Venda men and boys , Tracey, Andrew T N
- Date: 2002
- Subjects: Venda --(African people) , Folk dancing, Venda , Reed pipes (Organ pipes) , Drum , Instrumental music , Sub-Saharan African music , Africa South Africa Venda f-sa
- Language: Venda
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/112089 , vital:33546 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC126a-01
- Description: Instrumental Venda Tshikona reed pipe dance music
- Full Text: false
- Date Issued: 2002
Tshikona
- Authors: Venda men and boys , Tracey, Andrew T N
- Date: 2002
- Subjects: Venda --(African people) , Folk dancing, Venda , Reed pipes (Organ pipes) , Drum , Instrumental music , Sub-Saharan African music , Africa South Africa Venda f-sa
- Language: Venda
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/112099 , vital:33548 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC126a-03
- Description: Instrumental Venda Tshikona reed pipe dance music
- Full Text: false
- Date Issued: 2002
Tshikona
- Authors: Venda men and boys , Tracey, Andrew T N
- Date: 2002
- Subjects: Venda --(African people) , Folk dancing, Venda , Reed pipes (Organ pipes) , Drum , Instrumental music , Sub-Saharan African music , Africa South Africa Venda f-sa
- Language: Venda
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/112116 , vital:33549 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC126a-04
- Description: Instrumental Venda Tshikona reed pipe dance music with close up on individual pipes
- Full Text: false
- Date Issued: 2002
Tshikona
- Authors: Venda men and boys , Tracey, Andrew T N
- Date: 2002
- Subjects: Venda --(African people) , Folk dancing, Venda , Reed pipes (Organ pipes) , Drum , Instrumental music , Sub-Saharan African music , Africa South Africa Venda f-sa
- Language: Venda
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/112094 , vital:33547 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC126a-02
- Description: Instrumental Venda Tshikona reed pipe dance music
- Full Text: false
- Date Issued: 2002
Use of indigenous and indigenised medicines to enhance personal well-being: a South African case study
- Authors: Cocks, Michelle L , Moller, Valerie
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:7106 , http://hdl.handle.net/10962/d1010679
- Description: An estimated 27 million South Africans use indigenous medicines (Mander, 1997, Medicinal plant marketing and strategies for sustaining the plant supply in the Bushbuckridge area and Mpumalanga Province. Institute for Natural Resources, University of Natal, Pietermaritzburg, South Africa). Although herbal remedies are freely available in amayeza stores, or Xhosa chemists, for self-medication, little is known about the motivations of consumers. According to African belief systems, good health is holistic and extends to the person's social environment. The paper makes a distinction between traditional medicines which are used to enhance personal well-being generally and for cultural purposes, on the one hand, and medicines used to treat physical conditions only, on the other. Drawing on an eight-month study of Xhosa chemists in Eastern Cape Province, South Africa, in 1996, the paper identifies 90 medicines in stock which are used to enhance personal well-being. Just under one-third of all purchases were of medicines to enhance well-being. Remedies particularly popular included medicines believed to ward off evil spirits and bring good luck. The protection of infants with medicines which repel evil spirits is a common practice. Consumer behaviours indicate that the range of medicines available is increased by indigenisation of manufactured traditional medicines and cross-cultural borrowing. Case studies confirm that self- and infant medication with indigenous remedies augmented by indigenised medicines plays an important role in primary health care by allaying the fears and anxieties of everyday life within the Xhosa belief system, thereby promoting personal well-being.
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- Date Issued: 2002
Use patterns and value of savanna resources in three rural villages in South Africa
- Authors: Shackleton, Sheona E , Shackleton, Charlie M , Netshiluvhi, T R , Geach, B S , Ballance, A , Fairbanks, D H K
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182384 , vital:43825 , xlink:href="https://doi.org/10.1663/0013-0001(2002)056[0130:UPAVOS]2.0.CO;2"
- Description: Rural communities in South Africa harvest a diversity of wild resources from communal woodlands for home consumption and sale. The contribution these resources make to the rural economy has been little recognized, and few studies have attempted to place a monetary value on this use. This paper describes three case studies which aimed to determine the value of savanna resources for the livelihoods of rural households. Use patterns and values of resources in three villages of differing socioeconomic status were determined using household interviews, PRA techniques and key informant interviews. Questions were designed to establish the types of products used, frequency of use, quantities used, seasonality of use, longevity of durable resources, local prices, and the extent of trade. All households were procuring at least some woodland resources, with the most frequently used being fuel wood, wood for implements, edible herbs and fruits, grass for brushes, and insects. Patterns of resource use varied across villages. The most “rural” village used the greatest diversity of resources and had the highest number of users for most resources. Gross value of resources consumed per household per year ranged from R28I9 to R7238. Total value was highest in the less obviously resource dependent village, primarily the result of higher local prices due to greater extraction costs and a larger market for traded goods. Values are comparable to those contributed by other land-based livelihood activities such as subsistence cultivation and livestock production.
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- Date Issued: 2002
Valuation of intellectual capital in South African companies: a comparative study of three valuation methods
- Authors: Maree, Kevin W
- Date: 2002
- Subjects: Accounting
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:877 , http://hdl.handle.net/10962/d1001631
- Description: This study discusses three valuation methods for intellectual capital and considers two of these (Tobin’s “q” and CIV) as suitable valuation methods.
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- Date Issued: 2002
Valuing the arts: pitfalls in economic impact studies of arts festivals
- Authors: Snowball, Jeanette D , Antrobus, Geoffrey G
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143145 , vital:38205 , https://doi.org/10.1111/j.1813-6982.2002.tb00067.x
- Description: Economic impact studies have been used to measure the value of a variety of public and mixed goods, such as arts festivals, sports facilities and educational institutions, partly to motivate for public funds. The attraction of this sort of study rests largely on the fact that it produces a quantifiable monetary measure of the value of a project as opposed to a less easily valued qualitative study. “Public officials, boosters and the media accept the ‘quantifiable’ which appears to represent reality in order to justify a desired project” (Johnson and Sack 1996:370).
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- Date Issued: 2002
Vergelyking van Tilapia (Oreochromis Mossambicus)en Koi (Ciprinus Carpio) in verskillende produksiestelsels
- Authors: Van der Merwe, Johan Philip
- Date: 2002
- Subjects: Fish culture
- Language: Afrikaans
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10967 , http://hdl.handle.net/10948/114 , Fish culture
- Description: Die studie was uitgevoer om te bepaal of warmwaterspesies soos tilapia (Oreochromis mossambicus) en koi (Ciprinus carpio) gebruik kan word as deel van 'n roterende akwakultuur produksie sisteem in die Wes-Kaap. Drie produksiestelsels (drywende hokstelsel; gronddamme en hersirkuleringseenheid) was ge-evalueer vir beide tilapia en koi produksie. Twee verskillende diëte (tilapia, 32% proteien, 'n lae waarde dieet en koi, 32% proteien, 'n hoë waarde dieet) was ook ge-evalueer vir die effek op koi produksie. Tilapia- en koi vingerlinge was teen dieselfde lading (250/hok) in elke produksiestelsel geplaas. By die begin van die proewe het die tilapia vingerlinge 'n gemiddelde gewig van 60-80g en die koi vingerlinge 'n gemiddelde lengte van 30-40 mm gehad. Die visse is twee keer per dag gevoer en data is op 'n maandelikse basis oor 'n periode van 84 dae versamel. Produksie data vir die tilapia versamel was: 1) die gemiddelde daaglikse toename, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die produksie data versamel vir koi wat twee verskillende diëte ontvang het in drie verskillende produksiestelsels was: 1) die gemiddelde daaglikse toename in lengte, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die resultate van die tilapia studie het aangedui dat tilapia in die hersirkuleeringseenheid het deurgaans 'n swaarder gewig gehad (p<0.05) as die van die drywende hokstelsel en gronddam stelsel. Terwyl die gronddam stelsel weer 'n swaarder gewig gehad het as die drywende hokstelsel behalwe vir April (171,67 / 39,49 vs 159,33 / 22,15). Nieteenstaande die verskil in begin gewig en eind gewig in die guns van die tilapia in die hersirkuleringseenheid teenoor die ander twee stelsels het die GDT tussen die drywende hokstelsel en die hersirkuleringseenheid nie noemenswaardig verskil nie (1,20 / 0,15 vs 1,40 / 0,24). Die tilapia in die gronddamme het egter swakker (p<0,05) gewigstoename van 0,72 / 0,32 g gehad teenoor die tilapia in die drywende hokstesel 1,40 / 0,24 g en 1,20 / 0,15 g van die tilapia in die hersirkuleringseenheid. Tilapia in die gronddamme het dus ongeveer 45% swakker gemiddelde gewigstoename getoon as die van die drywende hokstelsel en hersirkuleringseenheid. Die produksiestelsel het 'n hoogs betekenisvolle invloed (p<0,001) op die groeipotensiaal van tilapia gehad in hierdie studie. Die gemiddelde totale hoeveelheid voer verbruik was nie statisties verskillend tussen die drywende hokstelsel en gronddam stelsel nie (29,83 / 2,66 vs 30,83 / 5,42), maar wel (p<0,05) vir die hersirkuleringseenheid (29,94 / 0,88). Die VOV het nie verskil tussen die drywende hokstelsel en hersirkuleringeenheid, maar daar was wel 'n verskil (p<0,05) tussen hierdie twee stelsels en die van die gronddamme. Die totale gemiddelde mortaliteite van tilapia was die hoogste (p<0,05) vir die drywende hokstelsel in vergelyking met die gronddamme en hersirkuleringseenheid. Die drywende hokstelsel het 14,67 / 14,61% meer mortaliteite gehad as die gronddamme en hersirkuleringeenheid. Die koi studie se resultate dui aan dat die tipe stelsel het 'n hoogs betekenisvolle (p<0,001) invloed gehad op die gemiddelde toename in lengte van die koi vis vir die somerseisoen. Die tipe dieet het geen invloed op die toename in lengte van koi vis vir al drie die stelsels ge-evalueer, maar die interaksie tussen dieet en die tipe stelsel was wel betekenisvol (p<0.05). Die interaksie tussen die tipe dieet en die tipe stelsel was die hoogste vir die groddamme 136,41 / 32,46 mm en 136,25 / 33,08 mm vir beide tilapia en die koi diëte gevoer. Die gemiddelde totale voer wat deur koi visse in die drie stelsels verbruik is, het wel statisties van mekaar verskil (p<0,05). Koi visse in die gronddam stelsel het meer voer verbruik vir beide die tilapia- en koi dieet (31,03 / 2,01 en 29,67 / 3,57) in vergelyking met die (26,35 / 2,44 ; 26,98 / 0,49 en 5,50 # 0,52 en 6,13 / 0,22) vir die drywende hokke en hersirkuleringseenheid stelsels onderskiedelik. Die % mortaliteite was betekenisvol (p<0,05) vir die verskillende stelsels. Koi visse in die hersirkuleringseenheid het die hoogste mortaliteite gehad vir beide die tilapia en die koi diëte (65,50 / 18,07% en 79,50 / 38,27%) terwyl koi visse in die gronddamme die laagste mortaliteite ondervind het (1,20 / 1,20% en 2,33 / 4,89%) vir beide die tilapia en koi diëte. Die koi in die gronddam stelsel het die beste resultate gelewer en dit is ook moontlik om koi 'n lae waarde dieet te voer sonder nadelige effekte op produksie.
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- Date Issued: 2002
Voltammetric characterization of the self-assembled monolayer (SAM) of octabutylthiophthalocyaninatoiron (II)
- Authors: Ozoemena,Kenneth , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290419 , vital:56748 , xlink:href="https://doi.org/10.1016/S0013-4686(02)00362-6"
- Description: The fabrication of a self-assembled monolayer (SAM) of 2,3,9,10,16,17,23,24-octa (butylthio)-phthalocyaninatoiron(II) [FePc(SBu)8] on gold electrode is described. The integrity of the SAM, with respect to its ability to block certain Faradaic processes, is interrogated using cyclic voltammetric experiments in aqueous solutions. The experiments show that this SAM provide an excellent blocking capability to the Faradaic processes emanating from gold surface oxidation, underpotential deposition (UPD) of copper and redox chemistry of Fe(NH4)(SO4)2 in HClO4. It is revealed by cyclic voltammetry that an ill-defined reversible couple of the SAM of FePc(SBu)8 can be greatly improved by a simple repetitive cycling of the modified electrode in a DMF solution containing TBAP within a short space of time (ca. 2 min). This ‘activation’ process provides good information concerning the surface coverage and orientation of the monolayer. The reversible redox wave shows a potential shift of about −57 mV per pH in the pH range of 2–9. A preliminary investigation indicates that FePc(SBu)8-SAM modified gold electrode shows electrocatalytic activity toward the oxidation of L-cysteine in acidic medium. The monolayer is stable and easily reproducible. However, due to its susceptibility to destruction via oxidative and reductive desorptions, its potential application as an electrochemical sensor would be much better in acidic and neutral than alkaline environments.
- Full Text:
- Date Issued: 2002
Voltammetric detection of vitamin B1 at carbon paste electrodes and its determination in tablets
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289692 , vital:56663 , xlink:href="https://doi.org/10.1002/1521-4109(200209)14"
- Description: The voltammetric behavior of vitamin B1 in alkaline medium at carbon paste electrode (CPE) is discussed. A method based on cyclic voltammetry for the determination of vitamin B1 at carbon paste electrode modified with manganese phthalocyanine (MnPc-CPE) is presented. In pH 10 buffer, the modified electrode showed catalytic activity towards the oxidation of vitamin B1 by considerably increasing the oxidation current of one of the observed waves compared to the oxidation current obtained at an unmodified electrode. The modified electrode was stable towards the determination of vitamin B1 compared to the unmodified electrode that is completely poisoned after a few scans. A linear relationship between the oxidation current and the concentration of vitamin B1 in solution was observed. The detection limit for vitamin B1 at the modified electrode was of the order of 10−5 mol dm−3. Commercial vitamin B1 tablets were analyzed using the modified electrodes.
- Full Text:
- Date Issued: 2002
Voltammetric detection of vitamin B1 at carbon paste electrodes and its determination in tablets
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289678 , vital:56662 , xlink:href="https://doi.org/10.1002/1521-4109(200209)14"
- Description: The voltammetric behavior of vitamin B1 in alkaline medium at carbon paste electrode (CPE) is discussed. A method based on cyclic voltammetry for the determination of vitamin B1 at carbon paste electrode modified with manganese phthalocyanine (MnPc-CPE) is presented. In pH 10 buffer, the modified electrode showed catalytic activity towards the oxidation of vitamin B1 by considerably increasing the oxidation current of one of the observed waves compared to the oxidation current obtained at an unmodified electrode. The modified electrode was stable towards the determination of vitamin B1 compared to the unmodified electrode that is completely poisoned after a few scans. A linear relationship between the oxidation current and the concentration of vitamin B1 in solution was observed. The detection limit for vitamin B1 at the modified electrode was of the order of 10−5 mol dm−3. Commercial vitamin B1 tablets were analyzed using the modified electrodes.
- Full Text:
- Date Issued: 2002