Photophysical and photochemical behaviour of metallophthalocyanines effect of nanoparticles and molecules of biological importance
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
- Full Text:
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
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The idea of regionalism in West and Southern Africa : a critical social enquiry
- Authors: Lindsay, Albert Domson
- Date: 2007
- Subjects: Regionalism -- Africa, West Regionalism -- Africa, Southern Africa, West -- Politics and government Africa, Southern -- Politics and government Africa -- Foreign relations
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2848 , http://hdl.handle.net/10962/d1006118
- Description: Traditional views on International Relations dominate regional analyses. These invariably emphasize the dominance of state and market forces in inter-state relations. Experiences and expectations of people are less prominent in these discourses, and the practices they foster. This thesis critically analyses the regional processes in West and southern Africa within the framework of Critical Theory. It argues that these processes are constrained by instability and the increasing legitimacy crises of the State. The thesis demonstrates that the State, through exclusive nationalist practices, hinder the growth of a cosmopolitan order, and it argues that neo-liberal regionalism is a contested phenomenon because of its exclusive nature. Finally, the thesis suggests steps needed to resolve the legitimacy crises and to build an inclusive regional order, based on cosmopolitan values.
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- Authors: Lindsay, Albert Domson
- Date: 2007
- Subjects: Regionalism -- Africa, West Regionalism -- Africa, Southern Africa, West -- Politics and government Africa, Southern -- Politics and government Africa -- Foreign relations
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2848 , http://hdl.handle.net/10962/d1006118
- Description: Traditional views on International Relations dominate regional analyses. These invariably emphasize the dominance of state and market forces in inter-state relations. Experiences and expectations of people are less prominent in these discourses, and the practices they foster. This thesis critically analyses the regional processes in West and southern Africa within the framework of Critical Theory. It argues that these processes are constrained by instability and the increasing legitimacy crises of the State. The thesis demonstrates that the State, through exclusive nationalist practices, hinder the growth of a cosmopolitan order, and it argues that neo-liberal regionalism is a contested phenomenon because of its exclusive nature. Finally, the thesis suggests steps needed to resolve the legitimacy crises and to build an inclusive regional order, based on cosmopolitan values.
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The psychological role of homoeroticism in the spiritual growth of priests: a study of individuation processes and homoerotic sexualities
- Authors: Taute, Harold Graeme
- Date: 2000
- Subjects: Homosexuality -- Psychological aspects Homosexuality -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3069 , http://hdl.handle.net/10962/d1002578
- Description: The study explored the psychological role of homoeroticism in the spiritual growth of priests, using Grounded Theory and James Fowler’s stages of faith development as the basis for the research methodology. Three Anglican priests were interviewed using a semi-structured interview format. The research interview combined Fowler’s Faith Development Interview Guide and a semi-structured interview in order to ascertain the priests’ level of spiritual development, as well as to explore their experience of the homoerotic component to their sexuality, and its influence on their spiritual growth. The interviews and iterative analysis focussed on four major questions: (1) Are priests who experience and actively work at integrating the homoerotic aspect to themselves assisted thereby in their spiritual growth, and if so, how might this be accounted for?; (2) Following Fowler’s model of spiritual development, what processes characterise each priest’s approach to meaning-creation in their lives?; (3) Following Fowler’s model, can the psychological work of engaging with and accepting homoeroticism be conceived of as serving an initiatory function in the emergence of new processes of meaning-creation?; (4) What role does homoeroticism serve in the spiritual growth of priests? The interpretative phase consisted of three stages. A grounded theory analysis of each interview was undertaken, developing a model for understanding the role of homoeroticism in spiritual growth. In the second stage, the priest’s level of spiritual development was ascertained, using Fowler’s Faith Development Guide. The third stage linked each participant’s level of spiritual development (in Fowler’s terms) with their core stories regarding experiences, meanings, and roles of homoeroticism. Finally, an integrative theory of the role of homoeroticism in spiritual growth was developed, using Jungian and post-Jungian theory as a basis for the discussion. The results suggested that homoeroticism did not play any role in spiritual growth and individuation separate to the manner in which it was experienced as having been constructed by society and the Church, and separate to the manner in which each priest in the study expressed, experienced, or engaged with it. In this context the experience of homoeroticism appeared to play a diversity of roles, including representing the collective and personal shadow, the archetypal anima/animus, the archetypal puer/senex constellation, the transcendent function, and thereby, as an expression of these roles, contribute to the emergence of new processes of meaning-creation in the spiritual growth and individuation of priests.
- Full Text:
- Authors: Taute, Harold Graeme
- Date: 2000
- Subjects: Homosexuality -- Psychological aspects Homosexuality -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3069 , http://hdl.handle.net/10962/d1002578
- Description: The study explored the psychological role of homoeroticism in the spiritual growth of priests, using Grounded Theory and James Fowler’s stages of faith development as the basis for the research methodology. Three Anglican priests were interviewed using a semi-structured interview format. The research interview combined Fowler’s Faith Development Interview Guide and a semi-structured interview in order to ascertain the priests’ level of spiritual development, as well as to explore their experience of the homoerotic component to their sexuality, and its influence on their spiritual growth. The interviews and iterative analysis focussed on four major questions: (1) Are priests who experience and actively work at integrating the homoerotic aspect to themselves assisted thereby in their spiritual growth, and if so, how might this be accounted for?; (2) Following Fowler’s model of spiritual development, what processes characterise each priest’s approach to meaning-creation in their lives?; (3) Following Fowler’s model, can the psychological work of engaging with and accepting homoeroticism be conceived of as serving an initiatory function in the emergence of new processes of meaning-creation?; (4) What role does homoeroticism serve in the spiritual growth of priests? The interpretative phase consisted of three stages. A grounded theory analysis of each interview was undertaken, developing a model for understanding the role of homoeroticism in spiritual growth. In the second stage, the priest’s level of spiritual development was ascertained, using Fowler’s Faith Development Guide. The third stage linked each participant’s level of spiritual development (in Fowler’s terms) with their core stories regarding experiences, meanings, and roles of homoeroticism. Finally, an integrative theory of the role of homoeroticism in spiritual growth was developed, using Jungian and post-Jungian theory as a basis for the discussion. The results suggested that homoeroticism did not play any role in spiritual growth and individuation separate to the manner in which it was experienced as having been constructed by society and the Church, and separate to the manner in which each priest in the study expressed, experienced, or engaged with it. In this context the experience of homoeroticism appeared to play a diversity of roles, including representing the collective and personal shadow, the archetypal anima/animus, the archetypal puer/senex constellation, the transcendent function, and thereby, as an expression of these roles, contribute to the emergence of new processes of meaning-creation in the spiritual growth and individuation of priests.
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The ninety piano preludes of Alexander Scriabin : an analysis
- Sumter-Loosen, Leonore Olga Elisabeth
- Authors: Sumter-Loosen, Leonore Olga Elisabeth
- Date: 1978
- Subjects: Scriabin, Aleksandr Nikolayevich, 1872-1915 -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2672 , http://hdl.handle.net/10962/d1007323
- Description: From thesis: Except perhaps for Debussy, Scriabin appears to be the most outstanding and productive composer amongst all his contemporaries in the field of the prelude. He wrote ninety preludes for the piano.
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- Authors: Sumter-Loosen, Leonore Olga Elisabeth
- Date: 1978
- Subjects: Scriabin, Aleksandr Nikolayevich, 1872-1915 -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2672 , http://hdl.handle.net/10962/d1007323
- Description: From thesis: Except perhaps for Debussy, Scriabin appears to be the most outstanding and productive composer amongst all his contemporaries in the field of the prelude. He wrote ninety preludes for the piano.
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Stratigraphy and sedimentology of the Cape and Karoo Sequences in the Eastern Cape Province
- Authors: Johnson, M R
- Date: 1976
- Subjects: Sediments (Geology) -- South Africa -- Eastern Cape Geology, Stratigraphic Sedimentology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5004 , http://hdl.handle.net/10962/d1005617
- Description: The Cape Supergroup (Sequence) comprises three groups, embracing a total of twenty-three formations, with a maximum combined thickness of approximately 8 km. The Table Mountain Group consists of medium-grained (occasionally fine- or coarse-grained), "clean", ultra-quartzose sandstone plus subordinate fine-grained, "dirty", subfeldspathic to feldspathic sandstone, mudrock, and rhythmitite. Average total thickness is about 3000 m. The Bokkeveld Group is composed of mudrock, rhythmitite and subordinate subfeldspathic to feldspathic sandstone (generally fine-grained and "dirty"), with a maximum total thickness of over 3000 m. The Witteberg Group comprises fine- to medium-grained ultra-quartzose sandstone, icaceous streaky rhythmitite, mudrock, and one thin diamictite unit; total thickness is about 1700 m. The strata belonging to the Cape Supergroup appear to have been largely deposited under marine conditions in environments ranging from outer shelf to beach. Deltaic deposits are,however, common in the upper part of the Bokkeveld Group and the Witteberg Group, while the main sandstone units in the upper third of the Table Mountain Group may have accumulated on a coastal alluvial plain. Deposition took place in a basin elongated in an east-west direction, with the palaeoslope inclined towards the south. Palaeocurrents were generally directed down the palaeoslope, but westerly 1 transport directions parallel to the palaeostrike and presumed shoreline are present in both the Table Mountain and Witteberg Groups. I The sedimentary rocks o~ the Karoo Sequence are subdivided into two groups (containing a total of eleven formations) and four ungrouped formations. Using the maximum thicknesses of the individual formations, a combined total thickness of about 12 km can be calculated. The sequence commences with the Dwyka Tillite, a 700-m-thick diamictite unit. The overlying Ecca Group consists of "varved" rhythmitite, dark, massive, fine- to very fine-grained ultra-lithofeldspathic sandstone and subordinate mudrock with a total thickness of 2000 - 3000 m. The Beaufort Group is composed of thick mudstone layers alternating with thinner fine-grained ultra-lithofeldspathic, lithofeldspathic and lithic sandstones, with the exception of the Katberg Formation which consists largely of sandstone. Fining-upward cycles are ubiquitous, while red mudstone is com~on, especially in the upper half of the group. A maximum thickness of about 6000 m was obtained in the East London area. The Molteno Formation Consists of up to 600 m of alternating fine- to coarse-grained sublithic sandstones (frequently pebbly) and grey mudstones, generally forming finingupward cycles. The Elliot Formation (up to 500 m thick) consists of red and grey mUdstones and subordinate fine-grained lithofeldspathic sandstones arranged in fining-upward cycles. The bulk of the Clarens Sandstone consists of very fine-grained massive (occasionally cross-bedded) sandstone, with a maximum thickness of 300 m. The Drakensberg Group, consisting of up to 1200 m of basalt with some pyroclastic intercalations near the base, caps the Karoo sedimentary succession. The deposition of the Dwyka Tillite by glacier action coincided with a major change from the generally shallow marine conditions which characterised the sedimentation of the Cape Supergroup (with the source area located on the craton to the north of the basin) to a deep linear trough receiving clastic sediments from a source area situated south and south-east of the basin. The Ecca Group,the lower half of which is characterised by the presence of "proximal" turbidite sandstones, records the gradual infilling of this basin, with deltaic conditions developing in the upper part of the group in the western half of the study area (i.e. in the Waterford Formation). The overlying strata were virtually all deposited under fluviatile conditions, the chief exceptions being a stratigraphic interval within the lower half of the Beaufort Group which appears to have formed in a large body of water, a~d the aeolian Clarens Sandstone. The fluviatile sediments were all deposite1 by rivers flowin~ towards the north and nort~-west, while the Clarens Sandstone was laid down by winds blowing from the west. The Ecca and Beaufort Group sandstones are characterised by a high rock fragment content with "felsit ic" gra ins being a prc;>minent constituent. This, together with the relative abundance of quartzfeldspar porphyry pebbles in the Katberg Sandstone unit (Beaufort Group) near East London, indicates that volcanic material probably formed a prominent part of the post-Dwyka Karoo provenance.
- Full Text:
- Authors: Johnson, M R
- Date: 1976
- Subjects: Sediments (Geology) -- South Africa -- Eastern Cape Geology, Stratigraphic Sedimentology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5004 , http://hdl.handle.net/10962/d1005617
- Description: The Cape Supergroup (Sequence) comprises three groups, embracing a total of twenty-three formations, with a maximum combined thickness of approximately 8 km. The Table Mountain Group consists of medium-grained (occasionally fine- or coarse-grained), "clean", ultra-quartzose sandstone plus subordinate fine-grained, "dirty", subfeldspathic to feldspathic sandstone, mudrock, and rhythmitite. Average total thickness is about 3000 m. The Bokkeveld Group is composed of mudrock, rhythmitite and subordinate subfeldspathic to feldspathic sandstone (generally fine-grained and "dirty"), with a maximum total thickness of over 3000 m. The Witteberg Group comprises fine- to medium-grained ultra-quartzose sandstone, icaceous streaky rhythmitite, mudrock, and one thin diamictite unit; total thickness is about 1700 m. The strata belonging to the Cape Supergroup appear to have been largely deposited under marine conditions in environments ranging from outer shelf to beach. Deltaic deposits are,however, common in the upper part of the Bokkeveld Group and the Witteberg Group, while the main sandstone units in the upper third of the Table Mountain Group may have accumulated on a coastal alluvial plain. Deposition took place in a basin elongated in an east-west direction, with the palaeoslope inclined towards the south. Palaeocurrents were generally directed down the palaeoslope, but westerly 1 transport directions parallel to the palaeostrike and presumed shoreline are present in both the Table Mountain and Witteberg Groups. I The sedimentary rocks o~ the Karoo Sequence are subdivided into two groups (containing a total of eleven formations) and four ungrouped formations. Using the maximum thicknesses of the individual formations, a combined total thickness of about 12 km can be calculated. The sequence commences with the Dwyka Tillite, a 700-m-thick diamictite unit. The overlying Ecca Group consists of "varved" rhythmitite, dark, massive, fine- to very fine-grained ultra-lithofeldspathic sandstone and subordinate mudrock with a total thickness of 2000 - 3000 m. The Beaufort Group is composed of thick mudstone layers alternating with thinner fine-grained ultra-lithofeldspathic, lithofeldspathic and lithic sandstones, with the exception of the Katberg Formation which consists largely of sandstone. Fining-upward cycles are ubiquitous, while red mudstone is com~on, especially in the upper half of the group. A maximum thickness of about 6000 m was obtained in the East London area. The Molteno Formation Consists of up to 600 m of alternating fine- to coarse-grained sublithic sandstones (frequently pebbly) and grey mudstones, generally forming finingupward cycles. The Elliot Formation (up to 500 m thick) consists of red and grey mUdstones and subordinate fine-grained lithofeldspathic sandstones arranged in fining-upward cycles. The bulk of the Clarens Sandstone consists of very fine-grained massive (occasionally cross-bedded) sandstone, with a maximum thickness of 300 m. The Drakensberg Group, consisting of up to 1200 m of basalt with some pyroclastic intercalations near the base, caps the Karoo sedimentary succession. The deposition of the Dwyka Tillite by glacier action coincided with a major change from the generally shallow marine conditions which characterised the sedimentation of the Cape Supergroup (with the source area located on the craton to the north of the basin) to a deep linear trough receiving clastic sediments from a source area situated south and south-east of the basin. The Ecca Group,the lower half of which is characterised by the presence of "proximal" turbidite sandstones, records the gradual infilling of this basin, with deltaic conditions developing in the upper part of the group in the western half of the study area (i.e. in the Waterford Formation). The overlying strata were virtually all deposited under fluviatile conditions, the chief exceptions being a stratigraphic interval within the lower half of the Beaufort Group which appears to have formed in a large body of water, a~d the aeolian Clarens Sandstone. The fluviatile sediments were all deposite1 by rivers flowin~ towards the north and nort~-west, while the Clarens Sandstone was laid down by winds blowing from the west. The Ecca and Beaufort Group sandstones are characterised by a high rock fragment content with "felsit ic" gra ins being a prc;>minent constituent. This, together with the relative abundance of quartzfeldspar porphyry pebbles in the Katberg Sandstone unit (Beaufort Group) near East London, indicates that volcanic material probably formed a prominent part of the post-Dwyka Karoo provenance.
- Full Text:
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