Electrocatalytic and photosensitizing behavior of metallophthalocyanine complexes
- Authors: Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265908 , vital:53899 , xlink:href="https://doi.org/10.1142/S1088424608000388"
- Description: Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co, Mn and Fe, whereas photosensitizing behavior is observed for diamagnetic metals such as Al, Zn and Si. In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
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- Date Issued: 2008
Electrocatalytic detection of amitrole on the multi-walled carbon nanotube–iron (II) tetra-aminophthalocyanine platform
- Authors: Siswana, Msimelelo P , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265924 , vital:53901 , xlink:href="https://doi.org/10.3390/s8085096"
- Description: It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions.
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- Date Issued: 2008
Electrochemical and electrocatalytic properties of α-substituted manganese and titanium phthalocyanines
- Authors: Nombona, Nolwazi , Tau, Prudence , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268587 , vital:54212 , xlink:href="https://doi.org/10.1016/j.electacta.2007.11.046"
- Description: This work reports on the synthesis of manganese and titanium phthalocyanine complexes that are tetra-substituted at four non-peripheral positions with amino ligands. The complexes are investigated for the first time for their electrochemical properties using cyclic voltammetry, rotating disc electrode voltammetry and spectroelectrochemistry. Electropolymerisation on a glassy carbon electrode was performed with ease and the modified electrodes were investigated for electrocatalysis of nitrite oxidation. Nitrite oxidation to nitrate is confirmed from the transfer of a total of two electrons.
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- Date Issued: 2008
Electrochemical Characterization of Self-Assembled Monolayer of a Novel Manganese Tetrabenzylthio-Substituted Phthalocyanine and Its Use in Nitrite Oxidation
- Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
- Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
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- Date Issued: 2008
Electrooxidation of hydrazine catalyzed by noncovalently functionalized single-walled carbon nanotubes with CoPc
- Authors: Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice L , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265963 , vital:53904 , xlink:href="https://doi.org/10.1016/j.electacta.2008.05.083"
- Description: We report on the electrooxidation of hydrazine catalyzed by single-walled carbon nanotube (SWCNT) functionalized with cobalt phthalocyanine (CoPc) which shows that the presence of the single-walled carbon nanotubes enhances the catalytic activity of the CoPc itself without any change in the reaction mechanism. A synergistic effect, in terms of reactivity when the new nanocomposite material was adsorbed on the GC electrode, was observed. The obtained hybrid electrodes were tested under hydrodynamic conditions, showing two different oxidation processes, which suggest the presence of two different types of active sites on the electrode surface catalyzing the reaction. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the GC/SWCNT + CoPc showed much lower electron-resistance (Ret) confirming the synergistic effect of the composite mentioned above. Atomic force microscopy (AFM) images showed the clear differences in surface roughness for each film, confirming the different compositions of the hybrid electrodes used in this study.
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- Date Issued: 2008
Employee performance, leadership style and emotional intelligence
- Authors: Hayward, Brett A , Amos, Trevor L , Baxter, Jeremy
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270077 , vital:54393 , xlink:href="https://hdl.handle.net/10520/EJC17031"
- Description: Purpose: The purpose of this research is to explore the relationship between employee performance, leadership style and emotional intelligence in the context of a South African parastatal. Problem Investigated: There is a lack of literature and empirical research on the type of leadership required to achieve high levels of employee performance within South African parastatals. Methodology: The Multifactor Leadership Questionnaire (MLQ) was used to determine leadership style, while the Emotional Competency Profiler (ECP) was used to determine the emotional intelligence of the sample of leaders. Employee performance data was provided by the parastatal, based on their performance management system. Data was analysed using correlation analysis, multiple regression analysis, the standard regression ANOVA/F-test, t-tests and Cronbach alpha reliability coefficient. Findings: The findings of the research show that the ECP is a reliable measure of emotional intelligence and that while the MLQ is a reliable measure of transformational leadership, it is not a reliable measure of transactional leadership. The results of the correlation analysis show a positive significant relationship between emotional intelligence and transformational leadership and a negative significant relationship between employee performance and emotional intelligence. The results of regressing employee performance on emotional intelligence and transformational leadership show that emotional intelligence and transformational leadership have no significant effect on employee performance. The results of the regression models of the research could be biased by the lack of variance in employee performance data. Value of the Research: The value of the research lies in it confirming the MLQ as a reliable measure of transformational leadership and the ECP as a reliable measure of emotional intelligence. The finding of a positive significant relationship between emotional intelligence and transformational leadership is a valuable contribution to the literature. Conclusion: Although a positive significant relationship between emotional intelligence and transformational leadership was found, there is a need for further research to determine the type of leadership best suited to achieve high levels of employee performance within the parastatal.
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- Date Issued: 2008
Energy transfer in zinc porphyrin–phthalocyanine heterotrimer and heterononamer studied by fluorescence resonance energy transfer (FRET)
- Authors: Durmus, Mahmut , Chen, Jiyao Y , Zhao, Zhixin X , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268599 , vital:54213 , xlink:href="https://doi.org/10.1016/j.saa.2007.07.010"
- Description: Two or eight zinc triphenyl porphyrins were conjugated with Zn-phthalocyanine or H2-phthalocyanine to form ZnPc–(ZnTPP)2, ZnPc–(ZnTPP)8, H2Pc–(ZnTPP)2 and H2Pc–(ZnTPP)8. Energy transfers from the porphyrin moiety to phthalocyanine part were quantitatively studied with the modality of fluorescence resonance energy transfer (FRET). By measuring the fluorescence increment from the phthalocyanine moiety and the decrease from porphyrin part under selective excitation at the B band of the porphyrin part in those conjugated compounds and their equimolar mixture of compositions, energy transfer efficiencies were estimated to be 90% for H2Pc–(ZnTPP)8 and ZnPc–(ZnTPP)8, and 60%, 30% for ZnPc–(ZnTPP)2 and H2Pc–(ZnTPP)2, respectively.
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- Date Issued: 2008
Engendering childhood: concerning the content of South African Television content
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2008
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/143560 , vital:38257 , ISBN , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: The essays in this volume reflect a wide-range of issues and concerns related to children’s media culture in Africa. For example, several address the role of entertainment television in Addis Abba, Ghana, South Africa, Kenya, and Zambia and in the lives of Muslim children. Other essays introduce us to children-centered media from Ghana, South Africa, and Zimbabwe, and the innovative programs of PLAN-International. In addition to entertainment media and children-centered media, media education and digital media literacy are also discussed.
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- Date Issued: 2008
Enhancing end-user capabilities in high speed audio networks
- Authors: Chigwamba, Nyasha , Foss, Richard
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427279 , vital:72427 , https://www.aes.org/e-lib/browse.cfm?elib=14266
- Description: Firewire is a digital network technology that can be used to interconnect professional audio equipment, PCs and electronic devices. The Plural Node Architecture splits connection management of firewire audio devices between two nodes, namely an Enabler and a Transporter. The Audio Engineering Society’s SC-02-12-G Task Group has produced an Open Generic Transporter guideline document which describes a generic interface between the Enabler and Transporter. A client-server implementation above the Plural Node Architecture allows connection management of firewire audio devices via TCP/IP. This paper describes enhancements made to connection management applications as a result of additional capabilities revealed by the Open Generic Transporter document.
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- Date Issued: 2008
Enigmatic trace fossils from the Aeolian lower Jurassic Clarens formation, Southern Africa
- Authors: Bordy, Emese M
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6730 , http://hdl.handle.net/10962/d1007538
- Description: The Lower Jurassic aeolienites of the Clarens Formation in southern Africa contain unique sedimentary structures that are unlikely to be non-biogenic. They are also unlike any known modern or ancient trace fossils. Here, some nigmatic, horizontal,regularly-oriented sedimentary structures are described, which occur in association with other trace fossils as well as features that were previously nterpreted as nests of termites or termite-like ancient social nsects. These spectacular structures are exposed in enormous profusion as straight, ~5 mm cylinders with strong compass orientation, in parallel alignment with one another and to ancient horizontal bedding planes. Their fill is identical to that of the host rock: clean, well-sorted, very fine- to finegrained quartz-arenite. In cross-section, each structure is defined by a subtle, ~0.1 mm thin, concentric gap. Without comparable modern biogenic structures, the biological origin of the structures is uncertain. Their strong compass orientations are, however, also inconsistent with an inorganic origin, even though they may resemble pipey concretions generated by flowing groundwater. Nonetheless, this paper, based on spatiotemporal distribution patterns of the oriented structures, their locally high abundance and association with obvious trace fossils, as well as other sedimentological and palaeontological lines of evidence, argues that the compass structures may be products of ancient social invertebrates living in a resource-limited, semi-arid to arid environment. Furthermore, the compass structures as well as the accompanying structures of the predominantly aeolian Clarens Formation collectively imply the recurrence of favourable ecological parameters (e.g., moist ubstrates) related to episodic climate fluctuations in the Early Jurassic of southern Pangaea (i.e., southern Gondwana).
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- Date Issued: 2008
Environmental Education and Educational Quality and Relevance-Opening the debate
- Authors: Lotz-Sisitka, Heila
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182668 , vital:43852 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122756"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) tackles a critical issue being debated across the world today, namely the question of educational quality and relevance. In 2005 the UNESCO Education for All Global Monitoring Report entitled Education for All: The Quality Imperative (UNESCO, 2004) was published. This global monitoring report drew attention to issues of educational quality, and raised the problem that physical access to education does not necessarily lead to epistemological access to knowledge or to relevant education being offered to learners. In the foreword to the 430-page assessment of educational quality issues, Koïchiro Matsuura, Director General of UNESCO, stated that ‘although much debate surrounds attempts to define educational quality, solid common ground exists … Quality must be seen in light of how societies define the purpose of education’ (UNESCO, 2004: Foreword). He went on to explain that there seem to be two mutually agreed upon purposes for education in the world today: cognitive development of learners, and creative and emotional growth of learners to help them acquire values and attitudes for responsible citizenship. He also pointed out that ‘quality must pass the test of equity’ (UNESCO, 2004: Foreword), emphasising the importance of equity of opportunity to access and participate in education and learning. Relevant to the field of environmental education, is the inclusion of educational quality as a major thrust of the United Nations Decade of Education for Sustainable Development (UNDESD) (UNESCO, 2004).
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- Date Issued: 2008
Environmental health work methods and procedures for the surveillance and control of avian influenza in the Eastern Cape Province, South Africa
- Authors: Elie, Sammy Abraham
- Date: 2008
- Subjects: Avian influenza -- Eastern Cape -- South Africa -- Prevention , Environmental health -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9834 , http://hdl.handle.net/10948/947 , http://hdl.handle.net/10948/d1009648 , Avian influenza -- Eastern Cape -- South Africa -- Prevention , Environmental health -- South Africa -- Eastern Cape
- Description: Avian influenza is an infectious disease of birds caused by the Type A strain of the influenza virus. The disease, which was first identified in Italy more than 100 years ago, occurs worldwide (World Health Organization, 2006a). The current outbreak of the highly pathogenic avian influenza A (H5N1), which began in Southeast Asia in mid-2003, is the largest and most severe on record. Never before in the recorded history of this disease have so many countries been simultaneously affected. Since the last pandemic in 1968-1969, the risk of an influenza pandemic has not been considered greater than at the present time. The importance of intervention strategies had become increasingly evident throughout the world. The World Health Organization provides a generic outline for preparedness plans to assist countries in their preparations to respond to a possible avian influenza pandemic. These guidelines may be modified as the epidemiology of avian influenza evolves. The South African National Department of Health has developed national guidelines in the form of an avian influenza preparedness plan. These draft guidelines do not provide detailed Environmental Health work methods and - procedures for the effective surveillance and control of the disease. The general purpose of this study is to develop a standardised set of Environmental Health work methods and - procedures, which will contribute to the effective surveillance and control of avian influenza in the Eastern Cape province – South Africa. Within the context of the purpose of this study, a qualitative, explorative, descriptive, inductive and deductive research design will be used. The methods of data collection will be documentary research, telephonic as well as in-depth personal interviews. In this study, documentary research will be the primary method of data collection. With a qualitative approach, the researcher will be the human instrument for data analysis. The process of qualitative data analysis will be based on data reduction and interpretation; and will be conducted as an activity simultaneously with data collection, data interpretation and narrative reporting writing.
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- Date Issued: 2008
Equiprime near-rings
- Authors: Mogae, Kabelo
- Date: 2008
- Subjects: Near-rings
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10505 , http://hdl.handle.net/10948/1028 , Near-rings
- Description: Prior to 1990, the only well known ideal-hereditary Kurosh-Amitsur radicals in the variety of zero-symmetric near-rings were the Jacobson type radicals Iv(N) , where ∨∈{2,3} and the Brown-McCoy radical. In 1990, Booth, Groenewald and Veldsman introduced the concept of an equiprime near-ring which leads to an ideal-hereditary Kurosh-Amitsur radical in N∘. The concept of an equiprime near-ring generalizes the concept of a prime ring to near-rings. Although the search for more ideal-hereditary radicals of near-rings was apparently the original motivation for the introduction of equiprime near-rings, it became clear that these near-rings are interesting in their own right. It is our aim in this treatise to give an exposition of the many interesting properties of equiprime near-rings. We begin with a brief reminder of near-ring rudiments; giving basic definitions and elementary results which are necessary for understanding and development of subsequent chapters. With the basics out of the way, our main task begins with a consideration of equiprime, strongly and completely equiprime left ideals. It is noted that any zero-symmetric near-ring can be embedded in an equiprime near-ring. Moreover, the class of equiprime near-rings is shown to be hereditary. Open questions arising out of the study of equiprime near-rings are highlighted along the way. In Chapter 3 we consider well known examples of near-rings and determine when such near-rings are equiprime. This provides more insight into the nature of equiprime near-rings and is a fertile ground for the birth of examples and counterexamples which may be used to close or solve some open question within the literature. We also prove some results which generalize some results of Booth and Hall [10] and Veldsman [29]. These results have not been previously presented elsewhere to the best of our knowledge. vii In Chapter 4, the equiprime near-rings are shown to yield an ideal-hereditary radical in N∘. It is shown that a special radical theory can be built on the equiprime nearrings in much the same way prime rings are used in ring theory to define special radical classes of rings.
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- Date Issued: 2008
Establishing a basis for ecosystem management in the western Indian Ocean
- Authors: Vousden, David , Scott, Lucy E P , Sauer, Warwick H H , Bornman, T G , Ngoile, M , Stapley, J , Lutjeharms, Johan R E
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6774 , http://hdl.handle.net/10962/d1008081
- Description: An ambitious multinational programme, with generous funding for an initial five years, aims to provide understanding of marine resources for the benefit of impoverished island and coastal populations in a much-neglected ocean region.
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- Date Issued: 2008
Estimating the age of immature Chrysomya albiceps (Diptera: Calliphoridae), correcting for temperature and geographical latitude
- Authors: Richards, Cameron S , Paterson, Iain D , Villet, Martin H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442129 , vital:73961 , https://doi.org/10.1007/s00414-007-0201-7
- Description: Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D 0) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671–682, 2000). Comparison with the K and D 0 values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D 0 is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis.
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- Date Issued: 2008
Evaluating and improving morpho-syntactic classification over multiple corpora using pre-trained, off-the-shelf, parts-of-speech tagging tools reviewed article
- Authors: Glass, Kevin R , Bangay, Shaun D
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433427 , vital:72969 , https://hdl.handle.net/10520/EJC28053
- Description: This paper evaluates six commonly available parts-of-speech tagging tools over corpora other than those upon which they were originally trained. In particular this investigation measures the performance of the selected tools over varying styles and genres of text without retraining, under the assumption that domain specific training data is not always available. An investigation is performed to determine whether improved results can be achieved by combining the set of tagging tools into ensembles that use voting schemes to determine the best tag for each word. It is found that while accuracy drops due to non-domain specific training, and tag-mapping between corpora, accuracy remains very high, with the support vector machine-based tagger, and the decision tree-based tagger performing best over different corpora. It is also found that an ensemble containing a support vector machine-based tagger, a probabilistic tagger, a decision-tree based tagger and a rule-based tagger produces the largest increase in accuracy and the largest reduction in error across different corpora, using the Precision-Recall voting scheme.
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- Date Issued: 2008
Evaluating service quality at George Municipality : a complaints management systems approach
- Authors: Alcock, Sandra
- Date: 2008
- Subjects: Consumer complaints -- South Africa -- George , Consumer satisfaction -- South Africa -- George , Customer services -- Management , Local government -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8717 , http://hdl.handle.net/10948/917 , Consumer complaints -- South Africa -- George , Consumer satisfaction -- South Africa -- George , Customer services -- Management , Local government -- South Africa -- George
- Description: The search for service and product quality has come to the forefront of business studies as the most important consumer trend of the past two decades. Studies conducted indicate that the 1990s saw a dramatic change in customer expectations concerning service quality and standards with a corresponding increase in the number of complaints from disgruntled customers. In response to this, many organisations have established customer care and complaints management services to respond to the need of customers. A substantial amount of literature exists on the subject of complaints management and its role in service quality, however, the focus has been on organisations in the private sector. The research undertaken in this paper aimed to investigate the role of complaints management systems (CMS) to evaluate service quality. The focus of this research was on local government with special attention on George Municipality. A literature review was done to establish the importance of service quality for local government as well as to investigate the link between an effective complaints management system and improvement in service quality. Furthermore, it was necessary to investigate the characteristics, design and implementation of an effective complaints management system. A questionnaire was developed in order to obtain primary data from a selected sample group. The data obtained from the questionnaire was statistically analysed and interpreted. The core findings from the analysed questionnaire indicated the following: service quality is relevant in local government; there is no clear method to measure service quality; no formal and structured complaints management system exist, and the implementation of an effective complaints management system will both improve service delivery and provide benefits to all involved. iv This study recommends that: service quality standards and measurement be of strategic importance to local government; customers should be consulted and involved when determining the service quality standards and measurement, and an organised and structured complaints management system that seeks to address all complaints in order to improve the level of service quality to customers be developed. Finally, the success of the CMS will depend on management’s commitment to change on a continuous basis as well as the degree to which management proactively resolves customer complaint through the involvement of the customer.
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- Date Issued: 2008
Evaluation of the effective micro-organisms (EM) on soil chemical properties and yield of selected vegetables in the Eastern Cape, South Africa
- Authors: Ncube, Lindani
- Date: 2008
- Subjects: Greenhouse management -- South Africa -- Eastern Cape , Butternut -- South Africa -- Eastern Cape , Microorganisms -- South Africa -- Eastern Cape , Sustainable agriculture -- South Africa -- Eastern Cape , Organic farming -- South Africa -- Eastern Cape , Tomatoes -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Horticultural Science)
- Identifier: vital:11886 , http://hdl.handle.net/10353/86
- Description: Effective microorganisms (EM), a commercial concoction of microbes that includes yeasts, fungi, bacteria and actinomycetes, have been found to be effective in enhancing crop growth by a number of scholars. It is registered in South Africa, but it had not been thoroughly investigated. The present study investigated the effects of EM on growth, yield and quality of tomato (Lycopersicon esculentum Mill), butternut (Curcurbita moschata) and Swiss chard (Beta vulgaris), along with selected soil properties. In field-grown tomato it was observed that the application of EM caused a significant increase in the number of fruits at seven weeks after transplanting. However, plants treated with EM alone, or EM in combination with other amendments, subsequently produced lower yields owing to an outbreak of early and late blights which affected them the most severely. Combined applications of EM with organic amendments improved plant N content and increased soil N content above initial levels. The application of compost resulted in soil N and P concentrations higher than those of the control presumably due to nutrients being slowly released from the compost material. In a follow up greenhouse trial EM application had a negative effect on tomato leaf dry matter yield, number of leaves, number of trusses, fruit yield and number of fruits. The negative effects of EM were ascribed to N immobilization by the EM that could have resulted in reduced N availability to plants. The lower number of fruits associated with EM application resulted in improved average fruit weight of tomatoes grown in the greenhouse, possibly as a result of more assimilates being partitioned to the few fruits EM application also had a negative effect on field grown butternut as reflected by lower total yield, lower marketable yield and lower first grade yield. The results were attributed to immobilization of N induced by application of EM, and to the inability of EM to control pumpkin fly that attacked very young fruit, resulting in their failure to develop or resulting in the down grading of mature fruits. The application of EM alone had a positive but non significant effect on the yields of both the first and second harvests of Swiss chard. However, when applied with compost or goat manure, a non significant negative effect on yield was observed. When applied with inorganic fertilizer, EM had no effect on yield but tended to increase the uptake of nitrogen by Swiss chard. Though goat manure had a narrower C: N ratio than compost, it did not result in greater EM effectiveness as had been hoped. However, goat manure had a more positive effect on soil properties than compost. It increased the N, P, and K contents of the soil and resulted in a narrower C: N ratio of the soil compared to compost. Generally, the results of the four trials conducted with three different crops indicated that EM had inconsistent effects on crop performance.
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- Date Issued: 2008
Evaluation of the pharmaceutical availability of erythromycin from topical formulations
- Authors: Mandimika, Nyaradzo
- Date: 2008
- Subjects: Pharmacy -- Research Chromatographic analysis Gel permeation chromatography Gels (Pharmacy) Chemistry, analytic Acne -- Treatment Sebaceous glands -- Diseases -- Treatment Drugs -- Testing Erythromycin -- Bioavailability
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3771 , http://hdl.handle.net/10962/d1003249
- Description: Erythromycin (ERY) is a macrolide antibiotic which is used in the treatment of acne vulgaris.Acne is a common skin condition that occurs when the sebaceous glands and hair shafts become infected by the bacteria Propionibacterium acnes. Acne is a chronic condition that may last for years and the severity of the effects of the disease on patients is often undermined especially in third world countries where more emphasis is placed on other more life-threatening diseases. It may cause considerable physical and emotional distress to sufferers along with the possibility of permanent scarring. Although use of topical ERY formulations is not the first line of treatment it has proven to be effective in treating inflammation of skin and skin structures cause by the responsible bacteria. To-date there are a variety of vehicles which are used in preparing topical ERY formulations namely ointment and gel bases, alcoholic solutions and pledgets. All the gel formulations on the market contain hydroxypropyl cellulose, alcohol and water along with the active ingredient(s). However, some gel formulations contain propylene glycol in addition to these excipients an example being Emgel®. Propylene glycol has been shown to affect the penetration of topically applied drugs through the skin suggesting that it would be highly likely that those formulations which contain propylene glycol may release more ERY into the skin following application. With this in mind, two ERY gel formulations were produced which contained different percentages of propylene glycol. According to the FDA guidelines, pharmacokinetic measurements in blood, plasma and/or urine of topical dermatological drug products are not feasible to document bioequivalence since the active ingredient(s) in topical formulations is/are not intended to be absorbed into the systemic circulation and in addition, concentrations in extracutaneous biological tissues would generally not be measurable. This limits determination of bioavailability and assessment of bioequivalence of such products to pharmacodynamic measurements, clinical trials and dermatopharmacokinetic (DPK) measurements such as tape stripping (TS) and microdialysis (MD).TS is a sampling technique which involves sequential removal of layers of the stratum corneum using strips of adhesive tape. This technique has found increasing use in DPK studies for investigation of drug kinetics in the skin following the application of a topical formulation. The technique has also been used as a diagnostic tool in assessing the quality of the stratum corneum in diseased skin. In the current research study, the tape stripping technique was used to investigate the pharmaceutical/biological availability of topical gel formulations containing ERY. MD is another DPK sampling technique which has been used to determine the amount of a topically applied drug that penetrates through the stratum corneum to reach deeper tissues of the skin. The in vivo sampling technique involves the insertion of microdialysis probes beneath the skin surface in the dermal tissue and allows for real-time sampling of the analyte at its target site. Recently in vitro MD has also been successfully used to assess the pharmaceutical availability of a topical corticosteroid, mometesone furoate, from topical formulations. Based on this work, microdialysis was used to determine the pharmaceutical availability of ERY from gel formulations which were developed for use in this research. The results of the pharmaceutical availability of ERY from in vivo tape stripping studies and the in vitro microdialysis studies were compared to establish correlation between the data. Pharmaceutical equivalence and bioequivalence data obtained from the respective studies on the gel formulations were investigated by statistical analysis of the data generated from both the in vitro and in vivo experiments. In summary the objectives of this research were: 1. To develop and validate a high performance liquid chromatography method suitable to analyse ERY concentrations obtained from in vitro microdialysis studies and in vivo tape stripping studies. 2. To prepare two different ERY gel formulations with different percentage content of propylene glycol. 3. To determine the pharmaceutical availability of ERY from two different gel formulations using in vitro microdialysis. 4. To develop and validate a tape stripping technique which could be used to determine percutaneous penetration and bioequivalence of the gel formulations. 5. To compare in vitro microdialysis and in vivo tape stripping data and attempt to establish a correlation between the two different approaches.
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- Date Issued: 2008
Excavating the 'critique' : an investigation into disjunctions between the espoused and the practiced within a Fine Art studio practice curriculum
- Authors: Belluigi, Dina Zoe
- Date: 2008
- Subjects: Art -- Study and teaching (Higher) Postmodernism and education Universities and colleges -- Philosophy Universities and colleges -- Curricula Education, Higher -- Political aspects Creative thinking -- Study and teaching Discourse analysis -- Methodology Critical pedagogy
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1531 , http://hdl.handle.net/10962/d1003413
- Description: This report presents the findings of a case study excavating the event of the ‘Critique’ (crit), the formative assessment method within a Fine Art Studio Practice curriculum. Arguments informed by critical postmodernism, education theories and contemporary art criticism are utilised to construct a dialectic of higher education, contemporary art and fine art studio practice. An emphasis is placed on the importance of agency, expressed through intentionality and critical thinking, with a recognition of the relationship between ‘the self’ and ‘the other’. Using critical discourse analysis, the disjunctions between the espoused and practiced curriculum are explored. The researcher analyses how the assessment practices of the case studied are influenced by unexamined agentic factors, such as inter-departmental relations, lecturers’ assumptions and prior learning, and structural determinants, such as the medium-specific Bachelor of Fine Art degree structure and prevailing artistic traditions. The research findings indicate that these are underpinned by tensions between two orientations, the espoused curriculum’s discourse-interest informed by critical theory, and the theory-in-use. The latter is shown to have unexamined modernist leanings towards formalism and a master-apprentice relationship between lecturer and students, which encourages reproduction rather than critical, creative thinking. The dominant discourses in the case studied construct a negative dialectic of the artist-student that can be seen to deny student agency and authorial responsibility. Findings suggest that students experience this as alienating, to the extent that to preserve their sense of self, they adopted surface and strategic approaches to learning. An argument is made for lecturers’ critically reflexive engagement with their teaching practice, and thereby to model ethical relationships between ‘self’ and ‘other’ during ‘crits’. In addition, emphasis is placed on how assessment practices should be more aligned with the espoused curriculum, so that the importance of a reflexive relationship between form and content, process and product, intentionality and interpretation is acknowledged.
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- Date Issued: 2008