Photophysical and photochemical studies of long chain-substituted zinc phthalocyanines
- Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
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- Date Issued: 2007
Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293279 , vital:57071 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
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- Date Issued: 2007
The synthesis, fluorescence behaviour and singlet oxygen studies of new water-soluble cationic gallium (III) phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/280207 , vital:55586 , xlink:href="https://doi.org/10.1016/j.inoche.2006.11.012"
- Description: The preparation of cationic water-soluble gallium phthalocyanine derivatives are described for the first time. Peripheral and non-peripheral 3-hydroxypyridine tetrasubstituted gallium(III)phthalocyanines (5a, 6a) and their quaternarized derivatives (5b and 6b) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternarized compounds (5b and 6b) are soluble in water and not aggregated (in water and in organic solvents) within a wide concentration range. General trends are described for singlet oxygen quantum yields, fluorescence quantum yields and fluorescence lifetimes of these compounds. These complexes showed better singlet oxygen quantum yields in water than the related quarternarized porphyrazine complexes.
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- Date Issued: 2007
Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283140 , vital:55914 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
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- Date Issued: 2007
Synthesis, photophysical and photochemical properties of aryloxy tetra-substituted gallium and indium phthalocyanine derivatives
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281431 , vital:55724 , xlink:href="https://doi.org/10.1016/j.tet.2006.11.089"
- Description: The synthesis, photophysical and photochemical properties of the tetra-substituted aryloxy gallium(III) and indium(III) phthalocyanines are reported for the first time. General trends are described for photodegradation, singlet oxygen, fluorescence, and triplet quantum yields and triplet lifetimes of these compounds. The introduction of phenoxy and tert-butylphenoxy substituents on the ring resulted in lowering of fluorescence quantum yields and lifetimes, and triplet quantum yields, and an increase of kIC, kISC, and kF. Photoreduction of the complexes was observed during laser flash photolysis. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.41 to 0.91. Thus, these complexes show potential as Type II photosensitizers.
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- Date Issued: 2007
Synthesis, photophysical and photochemical studies of new water-soluble indium (III) phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283976 , vital:56007 , xlink:href="https://doi.org/10.1039/b618478b"
- Description: The preparation of water-soluble indium(III)phthalocyanine complexes is described for the first time in this study. Peripherally and non-peripherally 3-hydroxypyridine tetrasubstituted indium(III) phthalocyanines (5a, 6a) and their quaternarized derivatives (5b, 6b) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternarized compounds (5b, 6b) show excellent solubility in water, which makes them potential photosensitizers for use in photodynamic therapy (PDT) applications. Photochemical and photophysical measurements were conducted on 3-pyridyloxy appended indium(III) phthalocyanines in dimethylsulfoxide (DMSO) for non-ionic (5b, 6b) derivatives. General trends are described for quantum yields of photodegradation, fluorescence lifetimes, fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) are very high (ΦΔ > 0.55). Thus, these complexes may be useful as Type II photosensitizers.
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- Date Issued: 2007
Synthesis, photophysical and photochemical properties of tetra-and octa-substituted gallium and indium phthalocyanines
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271276 , vital:54529 , xlink:href="https://doi.org/10.1016/j.poly.2007.03.007"
- Description: The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(III) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes (7b–9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes, compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields (ΦΔ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer.
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- Date Issued: 2007
An action learning based reflection on participative drama as a tool for transformation of identity in the spirals programme
- Authors: Edlmann, Tessa Margaret
- Date: 2007
- Subjects: Spirals Trust (South Africa) , Drama in education -- South Africa -- Grahamstown , Participatory theater -- South Africa -- Grahamstown , Active learning
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2159 , http://hdl.handle.net/10962/d1008202
- Description: This thesis is a reflection on both the conceptual frameworks and the personal narratives that have shaped the development of the Spirals Programme. The Programme is a participatory drama and creative arts based initiative established in 2000 in Grahamstown, South Africa, to explore issues of identity in the emerging democratic context of South African society - and support both personal and contextual processes of transformation. Working within a poststructuralist and social constructionist paradigm, Spirals works with groups and communities to facilitate and enable experiential links between the drama based and performative nature of identity construction - and the possibilities for transformation and healing provided by participative drama methodologies. The structure of the thesis follows the principles of the Freirian based Action Learning praxis within which Spirals works. It begins with an account of the contextual dynamics and events that gave rise to the development of the Programme, followed by a reflection on the conceptual frameworks regarding both identity construction and participative drama methodologies that informed Spirals' development. These paradigms are then analysed in relation to the articulated experiences of three workshop participants using critical discourse analysis. The thesis concludes with an assessment of the issues emerging from this analysis - the aspects of the Programme that need to be strengthened and sustained, those that need to be changed and possible new strategies that could be developed. , Also known as: Edlmann, Theresa
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- Date Issued: 2007
Collaborative versus adversarial stances in scientific discourse : implications for the role of systematic case studies in the development of evidence-based practice in psychotherapy
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6245 , http://hdl.handle.net/10962/d1007861
- Description: There is still a need for advocacy in the promotion of case study research because there has been insufficient appreciation of its role as a source of evidence relevant to the development and evaluation of practice in psychotherapy. Distorted use of terms like "gold standard", "anecdotal",and "empirical" in the discourse in which research methodology is typically presented has disempowered the practitioner's perspective and discredited the role of case-based knowledge building. The framework of evidence-based practice (EBP) recognizes the complementarity of different research methods and acknowledges the significance of casebased research. To spell out some of these complementary links, a typology of seven research methods - including both experimental group comparison designs and individual case studies - is proposed and the contribution of each to the development of EBP is set out. Finally some suggestions are made for strategies to promote the publication of high quality case studies.
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- Date Issued: 2007
Restructuring implicational meaning through memory-based imagery: some historical notes
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6239 , http://hdl.handle.net/10962/d1007851
- Description: This paper provides a historical perspective on the recent increase in the clinical application of imagery techniques to restructure systems of implicational meaning that drive emotional distress or self-defeating behaviors. Janet's early application of such techniques was largely ignored except by a few hypnotherapists. Current applications in cognitive therapy were adapted and extended in the early 1980s from Perls’ Gestalt therapy methods. Some precursors to Perls are examined, as well as the work of some of those who developed and formulated the integration of his techniques into Beck's cognitive therapy. It is argued that this process amounted to a significant paradigm shift.
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- Date Issued: 2007
The resurgence of tuberculosis in South Africa: an investigation into socio-economic aspects of the disease in a context of structural violence in Grahamstown, Eastern Cape
- Authors: Erstad, Ida
- Date: 2007
- Subjects: Tuberculosis -- South Africa -- Grahamstown Tuberculosis -- Patients -- South Africa -- Grahamstown Tuberculosis -- Treatment -- South Africa -- Grahamstown Community health services -- South Africa -- Grahamstown Medical anthropology -- South Africa -- Grahamstown Tuberculosis -- Economic aspects -- South Africa -- Grahamstown Tuberculosis -- Social aspects -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2090 , http://hdl.handle.net/10962/d1002653
- Description: This thesis is an investigation into the socio-economic constraints that influence the decisions of tuberculosis sufferers in the health seeking process and therapeutic management of tuberculosis in Grahamstown, the Eastern Cape. It is shown that structural violence influences experiences and perceptions of tuberculosis at all levels. Management of tuberculosis in the formal health sector is explored at local levels and related to national and global strategies of health care. The role of health workers, and particularly voluntary health workers, is explored and it is shown that they work within a context of growing burden of sickness and co-infections and a lack of government commitment to deal with increasing TB and HIV incidences. Kleinman’s notion of explanatory models is explored and it is evident that although knowledge of the aetiology of tuberculosis is well-known to patients and general members of the communities, they are nevertheless victims of increased stigmatisation and marginalisation as a result of illness. The importance of social support in curing tuberculosis is explored using Janzen’s concept of therapy managing groups. Social capital is a fundamental component in adhering to biomedical therapy, but is commonly weak among the structurally poor. The availability of temporary social grants for people living with TB influences health seeking behaviour. In a context of structural poverty the sick are faced with what Nattrass terms “perverse incentives”, having to choose between the right to health and the right to social security, both guaranteed in the South African Constitution, for him/herself and dependants. Although adherence to biomedical therapy is essential in curing tuberculosis, it is shown throughout this thesis that ignoring wider structural causes of disease limits the patient’s ability to get well. The ethnography shows that the right to health is a social and economic right which is not the reality for most South Africans.
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- Date Issued: 2007
The influence of vandalism in schools on learner's academic performance
- Authors: Esau, Vernon Garth
- Date: 2007
- Subjects: School vandalism -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9534 , http://hdl.handle.net/10948/691 , School vandalism -- South Africa -- Port Elizabeth
- Description: School vandalism is a serious problem in South Africa, particularly, as it places a heavy burden on education budgets. It could also cause learning to collapse, since it infringes on the right of learners to be taught in clean, well kept school buildings, and to develop their full potential. It is generally accepted that cared for school facilities, adequate furniture and equipment, as well as clean ablution facilities, are conducive to a healthy learning environment. The aim of this research was to determine whether vandalism at schools in Nelson Mandela Metropole (NMM) has an influence on learners’ scholastic achievement. Against the background of the literature review, this investigation endeavours to report on the nature and extent of vandalism at a sample of South African schools, as well as preventative measures that be introduced to combat such vandalism. The research comprised of a study of relevant literature, followed by a qualitative research design. The literature study covered aspects regarding the nature, extent and consequences of vandalism at schools. The sample group consisted of learners, teachers and parents from four secondary schools in the western region of the Uitenhage District. The respondents completed questionnaires regarding their viewpoints on the role that the school, the parents, the community, the police and the media could play in curbing acts of vandalism at schools. The respective principals and some members of staff were also interviewed. The research revealed that both teachers and learners were of the opinion that preventative measures need to be put in place to combat the scourge of vandalism at schools. However, such programmes should be implemented in collaboration with the community, the parents, the South African Police Services and the media. In conclusion some recommendations were made to combat the scourge of vandalism at schools and these may be of value to all schools in South Africa that experience similar problems.
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- Date Issued: 2007
"Muscled Presence": Douglas Livingstone's poem "Thirteen Ways of Looking at a Black Snake"
- Authors: Everitt, M , Wylie, D
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:2262 , http://hdl.handle.net/10962/d1004642
- Description: Douglas Livingstone's poem "Thirteen Ways of Looking at a Black Snake" is an artwork which addresses precisely these questions, seeking a manner of portraying the snake which is neither grossly appropriative nor wholly detached, neither ethically empty nor preachy. In its multi-angled structure, Livingstone attempts aesthetically "to establish and embellish ... a contact zone with the nonhuman animals who share our world with us, but accepting also that there exist considerable venues on either side of this contact zone that are, on the one hand, only human, and on the other hand, only nonhuman". Even in his more formally scientific work, Livingstone argues for the inevitability of such limits to knowledge, and for the value of the imagination in addressing them.
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- Date Issued: 2007
Land reform policies and human rights : a South African case study
- Authors: Fabbriciani, Antonio Antonino
- Date: 2007
- Subjects: Land reform -- South Africa -- Case studies , Human rights -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:9042 , http://hdl.handle.net/10948/502 , Land reform -- South Africa -- Case studies , Human rights -- South Africa -- Case studies
- Description: This treatise begins with a discussion of different clauses of the Bill of Rights in the South African Constitution and the land reform policies of the South African government. The inequality and injustice caused by decades of apartheid land law forms the background of the land reform programme. The treatise addresses the consequences of this legacy on the implementation of the South African Constitution including the right to property. The discussion includes the three key elements of the land reform programme namely restitution, redistribution and tenure reform. The content of this treatise ranges over these three elements of land reform, applying constitutional issues to the relevant case law, The balancing and the reconciliation of rights and interest between the individual and the public in a just manner will be the barometer. The conclusion shows that the Constitution both protects existing rights and authorises the promotion of land reform within the framework of Section 25 of the Constitution, and that every aspect of the property clause has to be regarded as part of a constitional effort in balancing individual interest and public interest in terms of a constitutional order. It is my sincere hope that this treatise will contribute toward the achievement of equity, stability and by the values of an open and democratic society based on human dignity, freedom and human rights.
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- Date Issued: 2007
The relevance of sustainable development principles and goals through a case study of Gold Fields and Living Gold
- Authors: Ferreira, Adrian
- Date: 2007
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192977 , vital:45286
- Description: The conventional definition of sustainable development as proposed by the Brundtland Report (United Nations, 1987), involving the integration of economic, social and environmental components, is widely accepted. Presumed benefits of these current framework applications tend to perpetuate a business as usual status, with no real sustainable development occurring. The growing debate surrounding this topic makes the case for relevant and contextual inputs to be included into sustainable development objectives. A case study, of Gold Fields and Living Gold, attempts to create a deeper understanding of the components of this debate, and begins to contextualise sustainable development principles, goals and their outcomes. This is carried out though an enquiry of the use of cultural development as a fourth sustainable development category. The case study includes the opinions of a directly affected local community entity (Living Gold) in order to observe the difference between the two organisations (Gold Fields and Living Gold). During the study, the focus began to move away from purely unabated growth impacts and looked to the creation and fostering of resilience and flexibility by the use of adaptive management. In breeding states of resilience, it was recognised that cultural impacts played an important role in ensuring long term systemic resilience. The case study involved assessing the feedback and responses of strategically selected individuals at both organisations, with Gold Fields representing a more western centric entity and Living Gold a formal representation of a traditional/ indigenous community. Similarities and differences were assessed in order to understand how current sustainable development criteria might differ between organisations that have different end objectives in mind, yet are dependent on each other. The findings resulted in a perspective of how culture could be used to describe the qualities of a local community, and how to begin aligning development goals with affected communities. The result was the development of the Integrated Resilience Sustainability Method and the consequent development of the Balanced Bottom Line Framework, which seeks to promote sustainable development along the lines of economic, social, environmental and cultural development. , Thesis (MBA) -- Faculty of Commerce, Rhodes Investec Business School, 2007
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- Date Issued: 2007
The psychofortology of male and female patients undergoing infertility treatment
- Authors: Ferreira, Hendrina Jacoba
- Date: 2007
- Subjects: Adjustment (Psychology) , Stress (Psychology) -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9918 , http://hdl.handle.net/10948/674 , Adjustment (Psychology) , Stress (Psychology) -- South Africa
- Description: Infertility is a complex condition associated with the inability to conceive a child, frequently manifesting itself as a result of various biological factors. A literature review indicated that being on Artificial Reproductive Technology (ART) treatment significantly increases the stress in an individual. While some research has been done on coping processes, and stress and depression levels in individuals on infertility treatment, very little literature is available regarding the coping resources and subjective well-being of individuals on infertility treatment. This psychofortigenic study aimed to explore and describe the coping resources, sense of coherence, satisfaction with life and life happiness of individuals undergoing infertility treatment. Furthermore, this study aimed to compare the coping resources, sense of coherence, satisfaction with life and happiness of males and females undergoing infertility treatment at a privately managed unit. It is imperative to view the results of this study from a gender-based perception as a previous study by Ferreira (2005) indicated significant differences in how males and females perceived infertility treatment. The sample in this study consisted of 62 voluntary participants from a privately managed health care unit in the Nelson Mandela Metropole. Participants were given a package of questionnaires to complete under the supervision of the researcher and research coordinator of the participating health care unit. The assessment consisted of a biographical questionnaire and four standardised paper and pencil measures. The participants’ coping resources were explored using Hammer and Marting’s (1988) Coping Resource Inventory (CRI), while Antonovsky’s (1987) Orientation to Life Scale was used to measure their sense of coherence (SOC-29). Overall satisfaction with life was assessed using Diener, Emmons, Larson and Griffin’s (1985) Satisfaction with Life Scale (SWLS), while Kamman and Flett’s (1993) Affectometer-2 (AFM-2) was utilized to measure the respondents’ subjective happiness. A quantitative, exploratory descriptive research design was employed in this study and the participants were chosen by means of a non-probability purposive sampling procedure. Data was analysed using descriptive statistics and independent t-testing. Further investigations were made through Chi square tests which enabled the researcher to draw inferences about differences based on cross tabulations. The reliability coefficient was obtained by calculating Cronbach’s coefficient alpha, which measured the internal consistency of the four standardized measures utilised in the present study. The results of the study revealed that participants generally experienced average levels of coping and subjective well-being as measured by the four assessment tools utilised during this study. On comparing the results of the male group and the female group of the particular sample it was found that although both groups obtained relatively average mean scores in general, the men scored slightly higher on the Coping Resources Inventory, Sense of Coherence and Affectometer-2, while the females scored slightly higher than the males on the Satisfaction with Life Scale.
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- Date Issued: 2007
Cytokine properties of CD23 on human Eosinophilic cells
- Authors: Ferreira, Lauren
- Date: 2007
- Subjects: Cytokines , CD23 antigen , Eosinophil
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10333 , http://hdl.handle.net/10948/503 , http://hdl.handle.net/10948/d1012001 , Cytokines , CD23 antigen , Eosinophil
- Description: CD23, the low affinity IgE receptor, is expressed by various cell types and has numerous functions depending on the form of the protein, its interaction with various ligands and the type of cell involved. CD23 is pivotal in the regulation of IgE, with the soluble form involved in up-regulation, while the membrane bound form is involved in the down-regulation. It is clear why it is believed to be a central molecule in allergic responses, and a therapeutic target for the treatment of allergic disease. In this study a recombinant form of the entire extracellular domain of the protein, exCD23, was produced by PCR cloning and expressed in E. coli. His•Tag™s were introduced onto the C-terminus and N-terminus, respectively, in order to simplify the purification procedure. After renaturation and purification, the recombinant exCD23 bound IgE, indicating its activity. From the IgE binding studies it was established that the position of the tag did not influence the binding. GST•Tagged™ exCD23 was also produced in an attempt to increase the solubility of the recombinant protein, but this proved unsuccessful. Butyrate differentiated EoL-1 cells were treated with the Nterminal His•Tagged™ exCD23, and the protein appeared to suppress the secretion of the constitutively expressed cytokines, especially IL-8 and IFN- , when compared to untreated cells. In addition, treatment of the EoL-1 cells with exCD23 had a significant proliferative effect, but could not induce differentiation of this cell line into mature eosinophilic-like cells.
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- Date Issued: 2007
Critical assessment of the quartz crystal microbalance with dissipation as an analytical tool for biosensor development and fundamental studies
- Authors: Fogel, Ronen , Mashazi, Philani N , Nyokong, Tebello , Limson, Janice
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271204 , vital:54521 , xlink:href="https://doi.org/10.1016/j.bios.2007.03.012"
- Description: One of the challenges in electrochemical biosensor design is gaining a fundamental knowledge of the processes underlying immobilisation of the molecules onto the electrode surface. This is of particular importance in biocomposite sensors where concerns have arisen as to the nature of the interaction between the biological and synthetic molecules immobilised. We examined the use of the Quartz Crystal Microbalance with Dissipation (QCM-D) as a tool for fundamental analyses of a model sensor constructed by the immobilisation of cobalt(II) phthalocyanine (TCACoPc) and glucose oxidase (GOx) onto a gold-quartz electrode (electrode surface) for the enhanced detection of glucose. The model sensor was constructed in aqueous phase and covalently linked the gold surface to the TCACoPc, and the TCACoPc to the GOx, using the QCM-D. The aqueous metallophthalocyanine (MPc) formed a multi-layer over the surface of the electrode, which could be removed to leave a monolayer with a mass loading that compared favourably to the theoretical value expected. Analysis of frequency and dissipation plots indicated covalent attachment of glucose oxidase onto the metallophthalocyanine layer. The amount of GOx bound using the model system compared favourably to calculations derived from the maximal amperometric functioning of the electrochemical sensor (examined in previously-published literature, Mashazi, P.N., Ozoemena, K.I., Nyokong, T., 2006. Electrochim. Acta 52, 177–186), but not to theoretical values derived from dimensions of GOx as established by crystallography. The strength of the binding of the GOx film with the TCACoPc layer was tested by using 2% SDS as a denaturant/surfactant, and the GOx film was not found to be significantly affected by exposure to this. This paper thus showed that QCM-D can be used in order to model essential processes and interactions that dictate the functional parameters of a biosensor.
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- Date Issued: 2007
Gowin's Knowledge Vee and the integration of philosophy and methodology : a case study
- Authors: Fox, Roddy C
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6682 , http://hdl.handle.net/10962/d1006677
- Description: Universities with a strong research tradition commonly have courses or modules examining the tradition’s philosophies and methodologies to prepare their students to undertake research programmes. Recently, however, authors have called for wider debate concerning how we teach these courses and this paper is intended, in part, to make a contribution to this debate. The Research Philosophy and Methodology module examined here makes an intriguing case study because of a number of distinctive characteristics. The teaching philosophy of the module is social constructivist and it uses Gowin’s Knowledge Vee as its main heuristic device. This facilitates the construction of knowledge about philosophy and methodology in an integrated manner. The module has also been designed for both physical and human geography students at the introductory post-graduate level. There is, therefore, a second element of integration in the curriculum. Lastly, the module is predominantly web-based, being taken by distance students through the exchange agreement between Rhodes University, South Africa, and the University of Trollhättan-Uddevalla, Sweden. Evidence from reflective exercises shows that the learners’ understanding of research and the research process has deepened considerably through using Gowin’s Vee. Furthermore, using the Knowledge Vee in the web-based context has facilitated the integrative aspects of the module.
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- Date Issued: 2007
Role playing African development : an international comparison
- Authors: Fox, Roddy C , Assmo, P , Kjellgren, H
- Date: 2007
- Language: English
- Type: Conference paper
- Identifier: vital:6665 , http://hdl.handle.net/10962/d1006676
- Description: The African Development Game is a role playing simulation developed to demonstrate the difficulties six African countries face in reaching the Millennium Development Goals. The game has been played in three different countries, South Africa, Sweden and Finland, to examine its utility as a learning tool for students who are unfamiliar both with the Millennium Development Goals and the problems of African development. Analysis of the games played in South Africa and Sweden. is based on a comparison of student reflections supplemented by participant observation and spreadsheet information of economic performances. Marked differences in the types of learning and success in repaying debt were observed between the two groups of students. They all commented, however, on the effectiveness of the role play as a learning tool.
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- Date Issued: 2007