Molecular phylogenetics of Oestroidea (Diptera: Calyptratae) with emphasis on Calliphoridae: insights into the inter-familial relationships and additional evidence for paraphyly among blowflies
- Marinho, M A T, Junqueira, A C M, Paulo, D F, Esposito, M C T, Villet, Martin H, Azeredo-Espin, A D
- Authors: Marinho, M A T , Junqueira, A C M , Paulo, D F , Esposito, M C T , Villet, Martin H , Azeredo-Espin, A D
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442691 , vital:74023 , https://doi.org/10.1016/j.ympev.2012.08.007
- Description: The superfamily Oestroidea, comprising ∼15,000 species, is a large and ecologically diverse clade within the order Diptera. Among its six commonly recognized families, Calliphoridae seems to be crucial for understanding evolutionary relationships in the group, as it is recognized as a controversial paraphyletic grouping. To further investigate this matter, the ITS2, 28S, COI and 16S regions were used to infer phylogenetic relationships in Oestroidea with maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian inference (BI) methods. For the BI analyses, a deep evaluation of different data partitioning strategies was conducted, including consideration of structural conformation (ITS2 and 16S) and codon position (COI) information.
- Full Text:
- Date Issued: 2012
- Authors: Marinho, M A T , Junqueira, A C M , Paulo, D F , Esposito, M C T , Villet, Martin H , Azeredo-Espin, A D
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442691 , vital:74023 , https://doi.org/10.1016/j.ympev.2012.08.007
- Description: The superfamily Oestroidea, comprising ∼15,000 species, is a large and ecologically diverse clade within the order Diptera. Among its six commonly recognized families, Calliphoridae seems to be crucial for understanding evolutionary relationships in the group, as it is recognized as a controversial paraphyletic grouping. To further investigate this matter, the ITS2, 28S, COI and 16S regions were used to infer phylogenetic relationships in Oestroidea with maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian inference (BI) methods. For the BI analyses, a deep evaluation of different data partitioning strategies was conducted, including consideration of structural conformation (ITS2 and 16S) and codon position (COI) information.
- Full Text:
- Date Issued: 2012
Mortgage bonds and the right of access to adequate housing in South Africa: Gundwana v Stoke Development and Others 2011 (3) SA 608 (CC)
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127479 , vital:36015 , https://hdl.handle.net/10520/EJC129329
- Description: This article offers a critique of Gundwana v Stoke Development and Others 2011 (3) SA 608 (CC), a case in which the Constitutional Court of South Africa found it to be unconstitutional for the registrar of a high court to declare immovable properties specially executable when ordering a default judgement, to the extent that such an order "permitted the sale and execution of a home of a person". The Court interpreted the property clause in section 25, access to right to housing in section 26 of the Constitution, as mandating "further judicial oversight" in all cases where execution is levied against residential property. The article raises some of the shortcomings of this interpretive scheme and suggests that constitutional values, when used to curtail or enlarge obligations of parties to a mortgage bond, must take into account the general rights and duties which the parties assumed at the signing of the agreement; the circumstances of each of the parties at the time of execution and ascertained through a careful evaluation based on a clearly articulated set of principles, and the nature of constitutional rights themselves. The article argues that, whereas there may be circumstances in which a debtor may need protection, rather than impose a blanket abrogation of procedures allowing for expedient disposal of uncontested claims, the court should instead have considered the establishment of further procedural safeguards.
- Full Text: false
- Date Issued: 2012
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127479 , vital:36015 , https://hdl.handle.net/10520/EJC129329
- Description: This article offers a critique of Gundwana v Stoke Development and Others 2011 (3) SA 608 (CC), a case in which the Constitutional Court of South Africa found it to be unconstitutional for the registrar of a high court to declare immovable properties specially executable when ordering a default judgement, to the extent that such an order "permitted the sale and execution of a home of a person". The Court interpreted the property clause in section 25, access to right to housing in section 26 of the Constitution, as mandating "further judicial oversight" in all cases where execution is levied against residential property. The article raises some of the shortcomings of this interpretive scheme and suggests that constitutional values, when used to curtail or enlarge obligations of parties to a mortgage bond, must take into account the general rights and duties which the parties assumed at the signing of the agreement; the circumstances of each of the parties at the time of execution and ascertained through a careful evaluation based on a clearly articulated set of principles, and the nature of constitutional rights themselves. The article argues that, whereas there may be circumstances in which a debtor may need protection, rather than impose a blanket abrogation of procedures allowing for expedient disposal of uncontested claims, the court should instead have considered the establishment of further procedural safeguards.
- Full Text: false
- Date Issued: 2012
Municipal commonage: an undervalued national resource
- Gambiza, James, Shackleton, Charlie M, Davenport, N, Atkinson, D, Hoffman, M T, Martens, C, Puttick, J, De Groot, W
- Authors: Gambiza, James , Shackleton, Charlie M , Davenport, N , Atkinson, D , Hoffman, M T , Martens, C , Puttick, J , De Groot, W
- Date: 2012
- Subjects: Land reform -- South Africa Land use -- South Africa South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/49969 , vital:25947
- Description: This policy brief will highlight the importance of municipal commonage in enhancing livelihoods of poor urban families. This will be followed by an overview of the role of municipal commonage in the land reform programme. Current challenges in securing benefits from municipal commonages are then outlined. Policy considerations to optimise benefits from commonages conclude the policy brief.
- Full Text:
- Date Issued: 2012
- Authors: Gambiza, James , Shackleton, Charlie M , Davenport, N , Atkinson, D , Hoffman, M T , Martens, C , Puttick, J , De Groot, W
- Date: 2012
- Subjects: Land reform -- South Africa Land use -- South Africa South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/49969 , vital:25947
- Description: This policy brief will highlight the importance of municipal commonage in enhancing livelihoods of poor urban families. This will be followed by an overview of the role of municipal commonage in the land reform programme. Current challenges in securing benefits from municipal commonages are then outlined. Policy considerations to optimise benefits from commonages conclude the policy brief.
- Full Text:
- Date Issued: 2012
Negotiating family planning radio messages among Malawian rural men of traditional authority Kadewere, Chiradzulo district
- Authors: Ntaba, Jolly Maxwell
- Date: 2012
- Subjects: Family planning -- Malawi , Birth control -- Malawi , Radio advertising -- Campaigns -- Malawi , Men -- Attitudes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3548 , http://hdl.handle.net/10962/d1018258
- Description: Family planning campaigns, using the media among other advocacy interventions, are produced and disseminated by both government and nongovernment organizations in Malawi, with an aim of reducing fertility and promotion of reproductive health. This qualitative audience study looks specifically at the reception by rural men of radio broadcast Public Service Announcements produced by the NGO, Banja La Mtsogolo, a leading provider of family planning services and products based in Blantyre. The aim of the study is to understand how the appropriation of these messages relates to traditional concepts of gender, masculinity and kinship within an area that has not been spared the influences, values and accoutrements of modernity. Underpinned by Hall’s encoding and decoding model, the study reveals that at most men make an oppositional reading of the texts based on their lived and shared cultural experiences. The results show that while people understand and appreciate the importance of family planning, cultural and traditional influences play a major role in how these messages are appropriated by and incorporated into the everyday lives of their listeners. Given the above understandings, the research asks what are the implications for the success of family-planning media campaigns by government and other non-governmental organisations such as Banja La Mtsogolo
- Full Text:
- Date Issued: 2012
- Authors: Ntaba, Jolly Maxwell
- Date: 2012
- Subjects: Family planning -- Malawi , Birth control -- Malawi , Radio advertising -- Campaigns -- Malawi , Men -- Attitudes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3548 , http://hdl.handle.net/10962/d1018258
- Description: Family planning campaigns, using the media among other advocacy interventions, are produced and disseminated by both government and nongovernment organizations in Malawi, with an aim of reducing fertility and promotion of reproductive health. This qualitative audience study looks specifically at the reception by rural men of radio broadcast Public Service Announcements produced by the NGO, Banja La Mtsogolo, a leading provider of family planning services and products based in Blantyre. The aim of the study is to understand how the appropriation of these messages relates to traditional concepts of gender, masculinity and kinship within an area that has not been spared the influences, values and accoutrements of modernity. Underpinned by Hall’s encoding and decoding model, the study reveals that at most men make an oppositional reading of the texts based on their lived and shared cultural experiences. The results show that while people understand and appreciate the importance of family planning, cultural and traditional influences play a major role in how these messages are appropriated by and incorporated into the everyday lives of their listeners. Given the above understandings, the research asks what are the implications for the success of family-planning media campaigns by government and other non-governmental organisations such as Banja La Mtsogolo
- Full Text:
- Date Issued: 2012
Network telescope metrics
- Authors: Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427944 , vital:72475 , https://www.researchgate.net/profile/Barry-Ir-win/publication/265121268_Network_Telescope_Metrics/links/58e23f70a6fdcc41bf973e69/Network-Telescope-Metrics.pdf
- Description: Network telescopes are a means of passive network monitoring, increasingly being used as part of a holistic network security program. One problem encountered by researchers in the sharing of the collected data form these systems. This is either due to the size of the data, or possibly a need to maintain the privacy of the Network address space being used for monitoring. This paper proposes a selection of metrics which can be used to communicate the most salient information contained in the data-set with other researchers, without the need to exchange or disclose the data-sets. Descriptive metrics for the sensor system are discussed along with numerical analysis data. The case for the use of graphical summary data is also presented.
- Full Text:
- Date Issued: 2012
- Authors: Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427944 , vital:72475 , https://www.researchgate.net/profile/Barry-Ir-win/publication/265121268_Network_Telescope_Metrics/links/58e23f70a6fdcc41bf973e69/Network-Telescope-Metrics.pdf
- Description: Network telescopes are a means of passive network monitoring, increasingly being used as part of a holistic network security program. One problem encountered by researchers in the sharing of the collected data form these systems. This is either due to the size of the data, or possibly a need to maintain the privacy of the Network address space being used for monitoring. This paper proposes a selection of metrics which can be used to communicate the most salient information contained in the data-set with other researchers, without the need to exchange or disclose the data-sets. Descriptive metrics for the sensor system are discussed along with numerical analysis data. The case for the use of graphical summary data is also presented.
- Full Text:
- Date Issued: 2012
Normandy: A Framework for Implementing High Speed Lexical Classification of Malicious URLs
- Egan, Shaun P, Irwin, Barry V W
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427958 , vital:72476 , https://www.researchgate.net/profile/Barry-Ir-win/publication/326224974_Normandy_A_Framework_for_Implementing_High_Speed_Lexical_Classification_of_Malicious_URLs/links/5b3f21074585150d2309dd50/Normandy-A-Framework-for-Implementing-High-Speed-Lexical-Classification-of-Malicious-URLs.pdf
- Description: Research has shown that it is possible to classify malicious URLs using state of the art techniques to train Artificial Neural Networks (ANN) using only lexical features of a URL. This has the advantage of being high speed and does not add any overhead to classifications as it does not require look-ups from external services. This paper discusses our method for implementing and testing a framework which automates the generation of these neural networks as well as testing involved in trying to optimize the performance of these ANNs.
- Full Text:
- Date Issued: 2012
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427958 , vital:72476 , https://www.researchgate.net/profile/Barry-Ir-win/publication/326224974_Normandy_A_Framework_for_Implementing_High_Speed_Lexical_Classification_of_Malicious_URLs/links/5b3f21074585150d2309dd50/Normandy-A-Framework-for-Implementing-High-Speed-Lexical-Classification-of-Malicious-URLs.pdf
- Description: Research has shown that it is possible to classify malicious URLs using state of the art techniques to train Artificial Neural Networks (ANN) using only lexical features of a URL. This has the advantage of being high speed and does not add any overhead to classifications as it does not require look-ups from external services. This paper discusses our method for implementing and testing a framework which automates the generation of these neural networks as well as testing involved in trying to optimize the performance of these ANNs.
- Full Text:
- Date Issued: 2012
Normative and institutional approaches to the protection of property rights of IDPs in Kenya's Rift Valley Province
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127464 , vital:36014 , https://doi.org/10.3366/ajicl.2012.0033
- Description: The post-election violence of 2008 which displaced about 600,000 people in six out of the eight provinces of Kenya1 has brought the plight of the internally displaced persons (IDPs) to the forefront of the national debate on politics and law. Transcending this debate is the sobering reality that inasmuch as the events of 2008 were catastrophic, they were a mere replay of the ethnically engineered political violence that Kenyans have had to endure before and after every major election since 1990.2
- Full Text: false
- Date Issued: 2012
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127464 , vital:36014 , https://doi.org/10.3366/ajicl.2012.0033
- Description: The post-election violence of 2008 which displaced about 600,000 people in six out of the eight provinces of Kenya1 has brought the plight of the internally displaced persons (IDPs) to the forefront of the national debate on politics and law. Transcending this debate is the sobering reality that inasmuch as the events of 2008 were catastrophic, they were a mere replay of the ethnically engineered political violence that Kenyans have had to endure before and after every major election since 1990.2
- Full Text: false
- Date Issued: 2012
Nothing but a mass of debris: urban evictions and the right of access to adequate housing in Kenya
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128425 , vital:36108 , http://www.scielo.org.za/scielo.php?script=sci_arttextamp;pid=S1996-20962012000200008amp;lng=enamp;nrm=iso
- Description: The article explores the opportunities that the new constitutional dispensation in Kenya has created for the protection against unlawful eviction of poor populations living in urban centres. It analyses the content of the right to accessible and adequate housing as provided for in article 43 of the Constitution of Kenya and articulated in various international instruments, and traces how this provision has been applied in the eviction cases that the Kenyan courts have decided. From this analysis, the article suggests that the new constitutional dispensation has opened up possibilities for rights enforcement that the courts as well as administrative organs should take advantage of. It also makes tangible suggestions on how to improve rights litigation in this regard, such as affirming the rights of access to courts and seeking further judicial oversight prior to any eviction and the promulgation of enabling legislation.
- Full Text:
- Date Issued: 2012
- Authors: Juma, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128425 , vital:36108 , http://www.scielo.org.za/scielo.php?script=sci_arttextamp;pid=S1996-20962012000200008amp;lng=enamp;nrm=iso
- Description: The article explores the opportunities that the new constitutional dispensation in Kenya has created for the protection against unlawful eviction of poor populations living in urban centres. It analyses the content of the right to accessible and adequate housing as provided for in article 43 of the Constitution of Kenya and articulated in various international instruments, and traces how this provision has been applied in the eviction cases that the Kenyan courts have decided. From this analysis, the article suggests that the new constitutional dispensation has opened up possibilities for rights enforcement that the courts as well as administrative organs should take advantage of. It also makes tangible suggestions on how to improve rights litigation in this regard, such as affirming the rights of access to courts and seeking further judicial oversight prior to any eviction and the promulgation of enabling legislation.
- Full Text:
- Date Issued: 2012
Optimisation of expression of a rice (Oryza sativa L.cv Nipponbare) plant natriuretic peptide (OsPNP-B) and its functional characterisation
- Authors: Affun, Ogheneochuko Janet
- Date: 2012
- Subjects: Rice , Plant hormones , Water-electrolyte imbalances
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24354 , vital:62644
- Description: Maintenance of water and solute homeostasis is a key requirement for living systems, and in vertebrates, homeostasis is in part achieved by natriuretic peptides (NP), a family of peptide hormones. A related family of peptide hormones have also been found in the plant kingdom. Plant natriuretic peptides (PNP) are a novel class of plant proteins with two closely related homologous genes (AtPNP-A and AtPNP-B) identified in the model plant Arabidopsis thaliana. AtPNP-A has been extensively studied and evidence obtained points to a role in plant water homeostasis. No research has been conducted on the function of PNP-B proteins. In this study, we focus on the bioinformatic analysis of the PNP-B gene in various plants, as well investigating whether PNP-B plays a role in water homeostasis in rice plants exposed to drought stress. Basic local alignment search tool (BLAST) queries of the ―The Gene Index‖, EST and available plant genome databases revealed the presence of the PNP-B mRNA in rice, oil seed rape, oak, leafy spurge, poplar, sugarcane, pepper, cotton, apple and maize. All the identified genome sequences contained a predicted intron/insert, which was not present in the related mRNA sequences. However, RT-PCR analysis revealed the presence of the 101 bp insert in the 976 bp amplified rice PNP-B (OsPNP-B) cDNA and therefore expression was optimized for the protein encoded by only the exon2 sequence as this contained the predicted active site region of PNP-B. OsPNP-B was shown to be translated to a protein of 14 kDa with a sequence similarity to AtPNP-B (54percent), AtPNP-A (37percent) and CjBAp12 (55percent), suggesting two possible functions for PNP-B viz water homeostasis and/or pathogenesis defence. To determine whether PNP-B is involved in water homeostasis, total protein extracted from 4 weeks old (4 leaves stage) rice plants subjected to drought treatment for a period of 24, 48, 72, 120, 168 and 240hrs were resolved by 17percent SDS-PAGE and analysed by western blot analysis. The PNP-B protein was found to be down-regulated during drought stress, implying that PNP-B may play a role in water homeostasis through the release of water from cells rather than the up-take of water as seen At-PNP-A. PNP-B could therefore also be involved in plant defence mechanisms to pathogens where plants induce desiccation of infected leaves, thereby ridding the plant of the relevant pathogen. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012
- Authors: Affun, Ogheneochuko Janet
- Date: 2012
- Subjects: Rice , Plant hormones , Water-electrolyte imbalances
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24354 , vital:62644
- Description: Maintenance of water and solute homeostasis is a key requirement for living systems, and in vertebrates, homeostasis is in part achieved by natriuretic peptides (NP), a family of peptide hormones. A related family of peptide hormones have also been found in the plant kingdom. Plant natriuretic peptides (PNP) are a novel class of plant proteins with two closely related homologous genes (AtPNP-A and AtPNP-B) identified in the model plant Arabidopsis thaliana. AtPNP-A has been extensively studied and evidence obtained points to a role in plant water homeostasis. No research has been conducted on the function of PNP-B proteins. In this study, we focus on the bioinformatic analysis of the PNP-B gene in various plants, as well investigating whether PNP-B plays a role in water homeostasis in rice plants exposed to drought stress. Basic local alignment search tool (BLAST) queries of the ―The Gene Index‖, EST and available plant genome databases revealed the presence of the PNP-B mRNA in rice, oil seed rape, oak, leafy spurge, poplar, sugarcane, pepper, cotton, apple and maize. All the identified genome sequences contained a predicted intron/insert, which was not present in the related mRNA sequences. However, RT-PCR analysis revealed the presence of the 101 bp insert in the 976 bp amplified rice PNP-B (OsPNP-B) cDNA and therefore expression was optimized for the protein encoded by only the exon2 sequence as this contained the predicted active site region of PNP-B. OsPNP-B was shown to be translated to a protein of 14 kDa with a sequence similarity to AtPNP-B (54percent), AtPNP-A (37percent) and CjBAp12 (55percent), suggesting two possible functions for PNP-B viz water homeostasis and/or pathogenesis defence. To determine whether PNP-B is involved in water homeostasis, total protein extracted from 4 weeks old (4 leaves stage) rice plants subjected to drought treatment for a period of 24, 48, 72, 120, 168 and 240hrs were resolved by 17percent SDS-PAGE and analysed by western blot analysis. The PNP-B protein was found to be down-regulated during drought stress, implying that PNP-B may play a role in water homeostasis through the release of water from cells rather than the up-take of water as seen At-PNP-A. PNP-B could therefore also be involved in plant defence mechanisms to pathogens where plants induce desiccation of infected leaves, thereby ridding the plant of the relevant pathogen. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012
Otoliths versus scales: evaluating the most suitable structure for ageing largemouth bass, Micropterus salmoides, in South Africa
- Taylor, Geraldine C, Weyl, Olaf L F
- Authors: Taylor, Geraldine C , Weyl, Olaf L F
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443907 , vital:74170 , https://doi.org/10.1080/15627020.2012.11407562
- Description: The suitability of scales for ageing Micropterus salmoides was determined by comparing the precision of growth zone counts on scales with those obtained from sectioned sagittal otoliths from a sample of 496 fish collected from Wriggleswade and Mankazana Impoundments in the Eastern Cape, South Africa. Otoliths (1.4% rejected) were more readable than scales (41.7% and 7.5% rejected) for Wriggleswade and Mankazana Impoundments respectively. Otolith readings were more precise (average percentage error (APE) = 13.6%; coefficient of variation (CV) = 15.8%) than scales (APE = 18.0%; CV = 21.9%) for the total sample. Growth zone counts between structures were not symmetrically distributed around the agreed ages (otolith age = scale age) of the fish from Wriggleswade Impoundment (Bowker’s test H2: χ2 = 136, d.f. = 27, P 0.05) and graphical comparison showed that scales tended to underestimate age, particularly for fish older than five years. Scales are therefore not suitable structures for ageing South African M. salmoides which may attain ages of up to 13 years.
- Full Text:
- Date Issued: 2012
- Authors: Taylor, Geraldine C , Weyl, Olaf L F
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443907 , vital:74170 , https://doi.org/10.1080/15627020.2012.11407562
- Description: The suitability of scales for ageing Micropterus salmoides was determined by comparing the precision of growth zone counts on scales with those obtained from sectioned sagittal otoliths from a sample of 496 fish collected from Wriggleswade and Mankazana Impoundments in the Eastern Cape, South Africa. Otoliths (1.4% rejected) were more readable than scales (41.7% and 7.5% rejected) for Wriggleswade and Mankazana Impoundments respectively. Otolith readings were more precise (average percentage error (APE) = 13.6%; coefficient of variation (CV) = 15.8%) than scales (APE = 18.0%; CV = 21.9%) for the total sample. Growth zone counts between structures were not symmetrically distributed around the agreed ages (otolith age = scale age) of the fish from Wriggleswade Impoundment (Bowker’s test H2: χ2 = 136, d.f. = 27, P 0.05) and graphical comparison showed that scales tended to underestimate age, particularly for fish older than five years. Scales are therefore not suitable structures for ageing South African M. salmoides which may attain ages of up to 13 years.
- Full Text:
- Date Issued: 2012
Oxovanadium (IV)-catalysed oxidation of dibenzothiophene and 4, 6-dimethyldibenzothiophene
- Ogunlaja, Adeniyi S, Chidawanyika, Wadzanai J U, Antunes, Edith M, Fernandes, Manuel A, Nyokong, Tebello, Torto, Nelson, Tshentu, Zenixole R
- Authors: Ogunlaja, Adeniyi S , Chidawanyika, Wadzanai J U , Antunes, Edith M , Fernandes, Manuel A , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246025 , vital:51429 , xlink:href="https://doi.org/10.1039/C2DT31433A"
- Description: The reaction between [VIVOSO4] and the tetradentate N2O2-donor Schiff base ligand, N,N-bis(o-hydroxybenzaldehyde)phenylenediamine (sal-HBPD), obtained by the condensation of salicylaldehyde and o-phenylenediamine in a molar ratio of 2 : 1 respectively, resulted in the formation of [VIVO(sal-HBPD)]. The molecular structure of [VIVO(sal-HBPD)] was determined by single crystal X-ray diffraction, and confirmed the distorted square pyramidal geometry of the complex with the N2O2 binding mode of the tetradentate ligand. The formation of the polymer-supported p[VIVO(sal-AHBPD)] proceeded via the nitrosation of sal-HBPD, followed by the reduction with hydrogen to form an amine group that was then linked to Merrifield beads followed by the reaction with [VIVOSO4]. XPS and EPR were used to confirm the presence of oxovanadium(IV) within the beads. The BET surface area and porosity of the heterogeneous catalyst p[VIVO(sal-AHBPD)] were found to be 6.9 m2 g−1 and 180.8 Å respectively. Microanalysis, TG, UV-Vis and FT-IR were used for further characterization of both [VIVO(sal-HBPD)] and p[VIVO(sal-AHBPD)]. Oxidation of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was investigated using [VIVO(sal-HBPD)] and p[VIVO(sal-AHBPD)] as catalysts. Progress for oxidation of these model compounds was monitored with a gas chromatograph fitted with a flame ionization detector. The oxidation products were characterized using gas chromatography-mass spectrometry, microanalysis and NMR. Dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) were found to be the main products of oxidation. Oxovanadium(IV) Schiff base microspherical beads, p[VIVO(sal-AHBPD)], were able to catalyse the oxidation of sulfur in dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to a tune of 88.0% and 71.8% respectively after 3 h at 40 °C. These oxidation results show promise for potential application of this catalyst in the oxidative desulfurization of crude oils.
- Full Text:
- Date Issued: 2012
- Authors: Ogunlaja, Adeniyi S , Chidawanyika, Wadzanai J U , Antunes, Edith M , Fernandes, Manuel A , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246025 , vital:51429 , xlink:href="https://doi.org/10.1039/C2DT31433A"
- Description: The reaction between [VIVOSO4] and the tetradentate N2O2-donor Schiff base ligand, N,N-bis(o-hydroxybenzaldehyde)phenylenediamine (sal-HBPD), obtained by the condensation of salicylaldehyde and o-phenylenediamine in a molar ratio of 2 : 1 respectively, resulted in the formation of [VIVO(sal-HBPD)]. The molecular structure of [VIVO(sal-HBPD)] was determined by single crystal X-ray diffraction, and confirmed the distorted square pyramidal geometry of the complex with the N2O2 binding mode of the tetradentate ligand. The formation of the polymer-supported p[VIVO(sal-AHBPD)] proceeded via the nitrosation of sal-HBPD, followed by the reduction with hydrogen to form an amine group that was then linked to Merrifield beads followed by the reaction with [VIVOSO4]. XPS and EPR were used to confirm the presence of oxovanadium(IV) within the beads. The BET surface area and porosity of the heterogeneous catalyst p[VIVO(sal-AHBPD)] were found to be 6.9 m2 g−1 and 180.8 Å respectively. Microanalysis, TG, UV-Vis and FT-IR were used for further characterization of both [VIVO(sal-HBPD)] and p[VIVO(sal-AHBPD)]. Oxidation of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was investigated using [VIVO(sal-HBPD)] and p[VIVO(sal-AHBPD)] as catalysts. Progress for oxidation of these model compounds was monitored with a gas chromatograph fitted with a flame ionization detector. The oxidation products were characterized using gas chromatography-mass spectrometry, microanalysis and NMR. Dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) were found to be the main products of oxidation. Oxovanadium(IV) Schiff base microspherical beads, p[VIVO(sal-AHBPD)], were able to catalyse the oxidation of sulfur in dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to a tune of 88.0% and 71.8% respectively after 3 h at 40 °C. These oxidation results show promise for potential application of this catalyst in the oxidative desulfurization of crude oils.
- Full Text:
- Date Issued: 2012
Parameter relationships in high-speed audio networks
- Chigwamba, Nyasha, Foss, Richard, Gurdan, Robby, Klinkradt, Bradley
- Authors: Chigwamba, Nyasha , Foss, Richard , Gurdan, Robby , Klinkradt, Bradley
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427027 , vital:72409 , https://www.aes.org/e-lib/browse.cfm?elib=16211
- Description: When related audio control parameters are distributed in many devices in a high-speed audio network, a means for centralizing remote control and monitoring is required. Changes in one parameter may need to affect other parameters. The XFN protocol enables management of distributed parameters. This paper focuses on how to group related parameters that are physically separated and provides a corresponding implementation using the protocol. A comprehensive grouping theory is presented.
- Full Text:
- Date Issued: 2012
- Authors: Chigwamba, Nyasha , Foss, Richard , Gurdan, Robby , Klinkradt, Bradley
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427027 , vital:72409 , https://www.aes.org/e-lib/browse.cfm?elib=16211
- Description: When related audio control parameters are distributed in many devices in a high-speed audio network, a means for centralizing remote control and monitoring is required. Changes in one parameter may need to affect other parameters. The XFN protocol enables management of distributed parameters. This paper focuses on how to group related parameters that are physically separated and provides a corresponding implementation using the protocol. A comprehensive grouping theory is presented.
- Full Text:
- Date Issued: 2012
Part II Zef/poor white kitsch chique
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225745 , vital:49255 , xlink:href="https://doi.org/10.1080/17533171.2012.715484"
- Description: Ninja, who fronts the freak hip-hop band Die Antwoord, might not be quite what Desmond Tutu had in mind when he described South Africans as the “Rainbow People of God,”24 a happy harmonious amalgamation of different races. In his introduction to their seminal comic track “Enter the Ninja,” Ninja presents himself, rather, as a mongrel gutter dog, both embracing and parodying a syncretic fusion of the many different cultures and races of South Africa, celebrating as well as subverting the rainbow nation discourse. As he said in an interview with News24: “South African culture is quite a fucking fruit salad … a fucking fucked rainbow nation. South Africa's totally fucked … but in a cool way.”25 The cool side of being “fucked” in this way is “Zef.” Zef denotes a particular style of vulgar humor (in the usual sense of the word “vulgar,” but also with a nod to its origin in the Latin vulgaris for “mob” or “commoners”), which has been emerging more and more in South Africa during the past decade. It involves a way of presenting a persona in a purposefully degrading way, exaggerating one's appearance and mannerisms as low class, ill bred, and boorish. I would like to consider the recent popularity of “Zef” and examine its connection specifically to popular Afrikaans folk rock culture, a lineage of white poverty, and the feeling of disgrace experienced by many white Afrikaners after the end of apartheid.
- Full Text:
- Date Issued: 2012
- Authors: Krueger, Anton
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225745 , vital:49255 , xlink:href="https://doi.org/10.1080/17533171.2012.715484"
- Description: Ninja, who fronts the freak hip-hop band Die Antwoord, might not be quite what Desmond Tutu had in mind when he described South Africans as the “Rainbow People of God,”24 a happy harmonious amalgamation of different races. In his introduction to their seminal comic track “Enter the Ninja,” Ninja presents himself, rather, as a mongrel gutter dog, both embracing and parodying a syncretic fusion of the many different cultures and races of South Africa, celebrating as well as subverting the rainbow nation discourse. As he said in an interview with News24: “South African culture is quite a fucking fruit salad … a fucking fucked rainbow nation. South Africa's totally fucked … but in a cool way.”25 The cool side of being “fucked” in this way is “Zef.” Zef denotes a particular style of vulgar humor (in the usual sense of the word “vulgar,” but also with a nod to its origin in the Latin vulgaris for “mob” or “commoners”), which has been emerging more and more in South Africa during the past decade. It involves a way of presenting a persona in a purposefully degrading way, exaggerating one's appearance and mannerisms as low class, ill bred, and boorish. I would like to consider the recent popularity of “Zef” and examine its connection specifically to popular Afrikaans folk rock culture, a lineage of white poverty, and the feeling of disgrace experienced by many white Afrikaners after the end of apartheid.
- Full Text:
- Date Issued: 2012
Patrick Hayes. JM Coetzee and the Novel: writing and politics after Beckett
- Authors: Marais, Mike
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144220 , vital:38322 , DOI: 10.1093/res/hgs014
- Description: According to Patrick Hayes, J. M. Coetzee's fiction, on a thematic level, ‘repeatedly suggests that the condition of modernity is made up of competing, equally important, and yet incommensurate ways of imagining the good community’ (p. 4). The first of these imaginings is grounded in the Kantian notion that the human individual is a rational and autonomous agent, and that it is precisely his or her rational autonomy, and capacity to direct life through neutral principles that commands the respect and recognition of other individuals. As is evident in its emphasis on rationality, this politic of equal dignity and recognition is universalistic in its claims. In contrast, the second imagining of community is based on the recognition of cultural specificity, and the argument that freedom and equal recognition are only possible through a revision of deleterious cultural stereotypes. In its terms, the good community ‘must be founded on the recognition, and active fostering of cultural particularity’ (p. 12). This politic of difference is highly suspicious of the universalizing claims of the politic of dignity, arguing that its appeal to equal dignity is itself a form of particularism masquerading as universalism.
- Full Text:
- Date Issued: 2012
- Authors: Marais, Mike
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144220 , vital:38322 , DOI: 10.1093/res/hgs014
- Description: According to Patrick Hayes, J. M. Coetzee's fiction, on a thematic level, ‘repeatedly suggests that the condition of modernity is made up of competing, equally important, and yet incommensurate ways of imagining the good community’ (p. 4). The first of these imaginings is grounded in the Kantian notion that the human individual is a rational and autonomous agent, and that it is precisely his or her rational autonomy, and capacity to direct life through neutral principles that commands the respect and recognition of other individuals. As is evident in its emphasis on rationality, this politic of equal dignity and recognition is universalistic in its claims. In contrast, the second imagining of community is based on the recognition of cultural specificity, and the argument that freedom and equal recognition are only possible through a revision of deleterious cultural stereotypes. In its terms, the good community ‘must be founded on the recognition, and active fostering of cultural particularity’ (p. 12). This politic of difference is highly suspicious of the universalizing claims of the politic of dignity, arguing that its appeal to equal dignity is itself a form of particularism masquerading as universalism.
- Full Text:
- Date Issued: 2012
Peat formation in the context of the development of the Mkuze floodplain on the coastal plain of Maputaland, South Africa:
- Ellery, William F N, Grenfell, Suzanne E, Grenfell, Michael C, Humphries, M S, Barnes, K, Dahlberg, S, Kindness, A
- Authors: Ellery, William F N , Grenfell, Suzanne E , Grenfell, Michael C , Humphries, M S , Barnes, K , Dahlberg, S , Kindness, A
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144354 , vital:38338 , DOI: 10.1016/j.geomorph.2011.11.009
- Description: This paper examines the geomorphological and sedimentological development of blocked-valley lakes in the Mkuze floodplain on the coastal plain of Maputaland, northern KwaZulu-Natal, South Africa. Blocked tributary valley lakes north of the floodplain become progressively shorter, broader, and less linear toward the eastern (downstream) end of the east–west oriented Mkuze floodplain. Clastic sediment forms surface sedimentary fill in tributary valleys in the west, while peat predominates tributary valley fill in the east. Two contrasting adjacent tributary valleys were examined, the more western Yengweni dominated by clastic sediment at the surface, and the more eastern Totweni with peat.
- Full Text:
- Date Issued: 2012
- Authors: Ellery, William F N , Grenfell, Suzanne E , Grenfell, Michael C , Humphries, M S , Barnes, K , Dahlberg, S , Kindness, A
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144354 , vital:38338 , DOI: 10.1016/j.geomorph.2011.11.009
- Description: This paper examines the geomorphological and sedimentological development of blocked-valley lakes in the Mkuze floodplain on the coastal plain of Maputaland, northern KwaZulu-Natal, South Africa. Blocked tributary valley lakes north of the floodplain become progressively shorter, broader, and less linear toward the eastern (downstream) end of the east–west oriented Mkuze floodplain. Clastic sediment forms surface sedimentary fill in tributary valleys in the west, while peat predominates tributary valley fill in the east. Two contrasting adjacent tributary valleys were examined, the more western Yengweni dominated by clastic sediment at the surface, and the more eastern Totweni with peat.
- Full Text:
- Date Issued: 2012
Perceptions and values of local landscapes: implications for the conservation of biocultural diversity and intangible heritage
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141442 , vital:37972 , ISBN 9789086867493 , DOI: 10.3920/978-90-8686-749-3_10
- Description: South Africa is widely recognised as a highly diverse country with regard to its people, culture, landscapes, biological resources and ecology. The importance of policies on protecting cultural diversity and how they relate to the environment is only just emerging at an international level, but in South African we find there is a complete lack of institutional support for rural communities’ attachment to local landscapes. The main objective of this case study is to improve our understanding of the meanings and values that Xhosa people (amaXhosa) of the Eastern Cape Province of South Africa attach to their natural landscapes. It is clear that the amaXhosa are still intrinsically connected to their natural environment, in particular the thicket biome that is called ihlathi yesiXhosa (Xhosa forest). Access to places and spaces within the natural environment provides a sense of wellbeing, a link to ancestral spirits, a location for religious rituals, plus a wealth of culturallyinspired uses of specific species and sacred places in the landscape. We suggest that local cultural values could be incorporated into the formal conservation process.
- Full Text:
- Date Issued: 2012
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141442 , vital:37972 , ISBN 9789086867493 , DOI: 10.3920/978-90-8686-749-3_10
- Description: South Africa is widely recognised as a highly diverse country with regard to its people, culture, landscapes, biological resources and ecology. The importance of policies on protecting cultural diversity and how they relate to the environment is only just emerging at an international level, but in South African we find there is a complete lack of institutional support for rural communities’ attachment to local landscapes. The main objective of this case study is to improve our understanding of the meanings and values that Xhosa people (amaXhosa) of the Eastern Cape Province of South Africa attach to their natural landscapes. It is clear that the amaXhosa are still intrinsically connected to their natural environment, in particular the thicket biome that is called ihlathi yesiXhosa (Xhosa forest). Access to places and spaces within the natural environment provides a sense of wellbeing, a link to ancestral spirits, a location for religious rituals, plus a wealth of culturallyinspired uses of specific species and sacred places in the landscape. We suggest that local cultural values could be incorporated into the formal conservation process.
- Full Text:
- Date Issued: 2012
PhDs by publications
- Niven, Penelope, Grant, Carolyn
- Authors: Niven, Penelope , Grant, Carolyn
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281108 , vital:55693 , xlink:href="https://doi.org/10.1080/13562517.2012.640086"
- Description: PhDs by publications are a relatively new model for doctoral research, especially in the context of the Humanities or Education. This paper describes two writers’ experiences of conducting doctoral studies in this genre and in these faculties. Each discover alternative ways of employing a body of published research papers in development of an overarching thesis. The writers argue that whilst it can be a pragmatic choice for some, PhDs by publications are more likely to be highly complex meta-narratives and that an overview of past research is fraught with theoretical, conceptual and epistemological challenges in the quest for coherence. They claim that the nomenclature ‘PhDs by publications’ or ‘through publications’ is misleading: in the epistemological space of Humanities or Education studies, this mode of doctoral research is more accurately represented as a ‘PhD with or alongside publications’. They conclude that the particular affordance of the model is that it privileges accounts of the process of knowledge building and of descriptions of the gradual emergence of ‘doctoralness’ in the person of the researcher.
- Full Text:
- Date Issued: 2012
- Authors: Niven, Penelope , Grant, Carolyn
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281108 , vital:55693 , xlink:href="https://doi.org/10.1080/13562517.2012.640086"
- Description: PhDs by publications are a relatively new model for doctoral research, especially in the context of the Humanities or Education. This paper describes two writers’ experiences of conducting doctoral studies in this genre and in these faculties. Each discover alternative ways of employing a body of published research papers in development of an overarching thesis. The writers argue that whilst it can be a pragmatic choice for some, PhDs by publications are more likely to be highly complex meta-narratives and that an overview of past research is fraught with theoretical, conceptual and epistemological challenges in the quest for coherence. They claim that the nomenclature ‘PhDs by publications’ or ‘through publications’ is misleading: in the epistemological space of Humanities or Education studies, this mode of doctoral research is more accurately represented as a ‘PhD with or alongside publications’. They conclude that the particular affordance of the model is that it privileges accounts of the process of knowledge building and of descriptions of the gradual emergence of ‘doctoralness’ in the person of the researcher.
- Full Text:
- Date Issued: 2012
Photooxidation of 4-chlorophenol sensitized by lutetium tetraphenoxy phthalocyanine anchored on electrospun polystyrene polymer fiber
- Zugle, Ruphino, Antunes, Edith M, Khene, Samson M, Nyokong, Tebello
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
Photophysical and photochemical properties of novel phthalocyanines bearing non-peripherally substituted mercaptoquinoline moiety
- Yaşa, Göknur, Erdoğmuş, Ali, Uğur, Ahmet Lütf, Şener, M Kasım, Avcıata, Ulvi, Nyokong, Tebello
- Authors: Yaşa, Göknur , Erdoğmuş, Ali , Uğur, Ahmet Lütf , Şener, M Kasım , Avcıata, Ulvi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244360 , vital:51250 , xlink:href="https://doi.org/10.1142/S1088424612500940"
- Description: The synthesis, photophysical and photochemical properties of nonperipherally (a) mercaptoquinoline substituted Zn(II), TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, 1 H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.
- Full Text:
- Date Issued: 2012
- Authors: Yaşa, Göknur , Erdoğmuş, Ali , Uğur, Ahmet Lütf , Şener, M Kasım , Avcıata, Ulvi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244360 , vital:51250 , xlink:href="https://doi.org/10.1142/S1088424612500940"
- Description: The synthesis, photophysical and photochemical properties of nonperipherally (a) mercaptoquinoline substituted Zn(II), TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, 1 H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.
- Full Text:
- Date Issued: 2012
Photophysical and photochemical studies of sulfur containing phthalocyanine derivatives in the presence of folic acid
- Nombona, Nolwazi, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012