SDF-1 and PDGF enhance αvβ5-mediated ERK activation and adhesion-independent growth of human pre-B cell lines:
- Acharya, Mridu, Edkins, Adrienne L, Ozanne, B, Cushley, W
- Authors: Acharya, Mridu , Edkins, Adrienne L , Ozanne, B , Cushley, W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165044 , vital:41204 , DOI: 10.1038/leu.2009.126
- Description: CD23 acts through the αvβ5 integrin to promote growth of human pre-B cell lines in an adhesion-independent manner. αvβ5 is expressed on normal B-cell precursors in the bone marrow. Soluble CD23 (sCD23), short CD23-derived peptides containing the arg-lys-cys (RKC) motif recognized by αvβ5 and anti-αvβ5 monoclonal antibodies (MAbs) all sustain growth of pre-B cell lines. The chemokine stromal cell-derived factor-1 (SDF-1) regulates key processes during B-cell development. SDF-1 enhanced the growth-sustaining effect driven by ligation of αvβ5 with anti-αvβ5 MAb 15F-11, sCD23 or CD23-derived RKC-containing peptides. This effect was restricted to B-cell precursors and was specific to SDF-1.
- Full Text:
- Date Issued: 2009
- Authors: Acharya, Mridu , Edkins, Adrienne L , Ozanne, B , Cushley, W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165044 , vital:41204 , DOI: 10.1038/leu.2009.126
- Description: CD23 acts through the αvβ5 integrin to promote growth of human pre-B cell lines in an adhesion-independent manner. αvβ5 is expressed on normal B-cell precursors in the bone marrow. Soluble CD23 (sCD23), short CD23-derived peptides containing the arg-lys-cys (RKC) motif recognized by αvβ5 and anti-αvβ5 monoclonal antibodies (MAbs) all sustain growth of pre-B cell lines. The chemokine stromal cell-derived factor-1 (SDF-1) regulates key processes during B-cell development. SDF-1 enhanced the growth-sustaining effect driven by ligation of αvβ5 with anti-αvβ5 MAb 15F-11, sCD23 or CD23-derived RKC-containing peptides. This effect was restricted to B-cell precursors and was specific to SDF-1.
- Full Text:
- Date Issued: 2009
Characterization of polymeric film of a new manganese phthalocyanine complex octa-substituted with 2-diethylaminoethanethiol, and its use for the electrochemical detection of bentazon
- Akinbulu, Isaac A, Nyokong, Tebello
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
A civic engagement:
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159366 , vital:40291 , https://hdl.handle.net/10520/EJC139908
- Description: Rod Amner looks at how a small South African newspaper is managing to punch well above its weight.
- Full Text:
- Date Issued: 2009
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159366 , vital:40291 , https://hdl.handle.net/10520/EJC139908
- Description: Rod Amner looks at how a small South African newspaper is managing to punch well above its weight.
- Full Text:
- Date Issued: 2009
Film Review: Hollywood on Safari
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142680 , vital:38101 , https://doi.org/10.1386/jams.1.2.335_4
- Description: Film Review: Hollywood on Safari.
- Full Text:
- Date Issued: 2009
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142680 , vital:38101 , https://doi.org/10.1386/jams.1.2.335_4
- Description: Film Review: Hollywood on Safari.
- Full Text:
- Date Issued: 2009
Paper recycling patterns and potential interventions in the education sector: A case study of paper streams at Rhodes University, South Africa
- Amutenya, N, Shackleton, Charlie M, Whittington-Jones, Kevin J
- Authors: Amutenya, N , Shackleton, Charlie M , Whittington-Jones, Kevin J
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181180 , vital:43705 , xlink:href="https://doi.org/10.1016/j.resconrec.2008.12.001"
- Description: This paper considers the use of paper by academics and student computer laboratories at Rhodes University as a basis for identifying areas to reduce the amounts used and increase rates of recycling. A sample of 50 academic staff monitored the volume and purpose of the paper they used over 5 months, and the procurement officers in all the academic departments were interviewed regarding the total amount of paper used per academic department. Mean use was 34 ± 20 new sheets of paper per working day, of which 3% were trashed, 15% were kept for later use (as scrap or printed on the opposite side) and 79% were given out as notes to students, filed as records or posted out as mail to other departments or institutions. There was a significant relationship between number of students served by a department and the overall demand for paper, as well the number of staff per department and the number of recycling bins. The university could save approximately US$ 7000 per year for every 10% reduction in current use of paper (12,784 reams/year). Reduction in paper usage could be achieved through an increase in re-use of paper, printing handouts for students on both sides of each sheet of paper and by investing in printers that are capable of printing on both sides of a sheet of paper. Double-sided printers are only 20–25% more expensive than single-sided ones, but will potentially reduce paper usage by half. A 40% reduction would save the university approximately US $ 20,000 per year in direct costs, and more in reduced waste streams, as well as help promote the environmental image of the university. On a per unit basis, the higher costs for a double-sided printer in offices would be repaid in 9 months or less through reduced paper use.
- Full Text:
- Date Issued: 2009
- Authors: Amutenya, N , Shackleton, Charlie M , Whittington-Jones, Kevin J
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181180 , vital:43705 , xlink:href="https://doi.org/10.1016/j.resconrec.2008.12.001"
- Description: This paper considers the use of paper by academics and student computer laboratories at Rhodes University as a basis for identifying areas to reduce the amounts used and increase rates of recycling. A sample of 50 academic staff monitored the volume and purpose of the paper they used over 5 months, and the procurement officers in all the academic departments were interviewed regarding the total amount of paper used per academic department. Mean use was 34 ± 20 new sheets of paper per working day, of which 3% were trashed, 15% were kept for later use (as scrap or printed on the opposite side) and 79% were given out as notes to students, filed as records or posted out as mail to other departments or institutions. There was a significant relationship between number of students served by a department and the overall demand for paper, as well the number of staff per department and the number of recycling bins. The university could save approximately US$ 7000 per year for every 10% reduction in current use of paper (12,784 reams/year). Reduction in paper usage could be achieved through an increase in re-use of paper, printing handouts for students on both sides of each sheet of paper and by investing in printers that are capable of printing on both sides of a sheet of paper. Double-sided printers are only 20–25% more expensive than single-sided ones, but will potentially reduce paper usage by half. A 40% reduction would save the university approximately US $ 20,000 per year in direct costs, and more in reduced waste streams, as well as help promote the environmental image of the university. On a per unit basis, the higher costs for a double-sided printer in offices would be repaid in 9 months or less through reduced paper use.
- Full Text:
- Date Issued: 2009
Synthesis and photophysical behavior of axially substituted phthalocyanine, tetrabenzotriazaporphyrin, and triazatetrabenzcorrole phosphorous complexes
- Antunes, Edith M, Nyokong, Tebello
- Authors: Antunes, Edith M , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264518 , vital:53741 , xlink:href="https://doi.org/10.1142/S1088424609000048"
- Description: The synthesis of phosphorous phthalocyanines, triazatetrabenzcorroles, and tetrabenzotriazaporphyrins with a variety of axial ligands is reported. The new complexes are: phosphorous dihydroxy tetrabenzotriazaporphyrin (5, PV(OH)2TBTAP), diphenyl phosphorous phthalocyanine (6, [PV(Ph)2Pc](OH)), diphenyl phosphorous triazatetrabenzcorrole (7, PV(Ph)2TBC), and dioctyl phosphorous triazatetrabenzcorrole (8, PV(C8H17)2TBC). The complexes are not aggregated in dimethylsulfoxide (DMSO) and pyridine. Upon axial coordination of a phenyl or octyl group, the complexes are soluble (and not aggregated) in dichloromethane (DCM) and tetrahydrofuran (THF). The triplet lifetimes range from 395 to 546 μs (for complexes 5 to 8), with the P(Ph)2TBC (7) complex showing the longest triplet lifetime (546 μs), while the smallest triplet quantum yield (ΦT = 0.27) was obtained for the [P(Ph)2Pc](OH) (6) complex. [P(OH)2Pc](OH) (3) showed the shortest triplet lifetime (113 μs) and the largest triplet quantum yield (ΦT = 0.52).
- Full Text:
- Date Issued: 2009
- Authors: Antunes, Edith M , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264518 , vital:53741 , xlink:href="https://doi.org/10.1142/S1088424609000048"
- Description: The synthesis of phosphorous phthalocyanines, triazatetrabenzcorroles, and tetrabenzotriazaporphyrins with a variety of axial ligands is reported. The new complexes are: phosphorous dihydroxy tetrabenzotriazaporphyrin (5, PV(OH)2TBTAP), diphenyl phosphorous phthalocyanine (6, [PV(Ph)2Pc](OH)), diphenyl phosphorous triazatetrabenzcorrole (7, PV(Ph)2TBC), and dioctyl phosphorous triazatetrabenzcorrole (8, PV(C8H17)2TBC). The complexes are not aggregated in dimethylsulfoxide (DMSO) and pyridine. Upon axial coordination of a phenyl or octyl group, the complexes are soluble (and not aggregated) in dichloromethane (DCM) and tetrahydrofuran (THF). The triplet lifetimes range from 395 to 546 μs (for complexes 5 to 8), with the P(Ph)2TBC (7) complex showing the longest triplet lifetime (546 μs), while the smallest triplet quantum yield (ΦT = 0.27) was obtained for the [P(Ph)2Pc](OH) (6) complex. [P(OH)2Pc](OH) (3) showed the shortest triplet lifetime (113 μs) and the largest triplet quantum yield (ΦT = 0.52).
- Full Text:
- Date Issued: 2009
On location: Narratives of the South African city of the late 1940s and 1950s in film and literature
- Authors: Baines, Gary F
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125397 , vital:35779 , https://doi.10.1080/02582470308671922
- Description: This article is about narratives, about the forms and meanings constructed by South African storytellers, especially writers and filmmakers. It examines the relationships between examples of these two different narrative forms of literature (fiction and non-fiction) and feature film. Following Turner, the point of departure is that the study of narrative has the potential to provide a framework within which such a two pronged approach can be undertaken. This is not to say that the production of meaning takes place within an exclusive literary or cinematic context. Rather, this approach will allow us to obtain a fuller picture of the narrative of the South African city than is possible by concentrating on one medium. It is based on the premise that narratives are ultimately produced by culture; thus these cultural constructions generate meanings, take on a significance, and assume forms that are articufations of the values, beliefs -the ideology - of the culture.' Literature and film offer specific forms for such narratives. By adopting an interdisciplinary approach which borrows insights from literary and film studies, this article attempts to make a contribution to the fledgling field of South African cultural studies.
- Full Text:
- Date Issued: 2009
On location: Narratives of the South African city of the late 1940s and 1950s in film and literature
- Authors: Baines, Gary F
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125397 , vital:35779 , https://doi.10.1080/02582470308671922
- Description: This article is about narratives, about the forms and meanings constructed by South African storytellers, especially writers and filmmakers. It examines the relationships between examples of these two different narrative forms of literature (fiction and non-fiction) and feature film. Following Turner, the point of departure is that the study of narrative has the potential to provide a framework within which such a two pronged approach can be undertaken. This is not to say that the production of meaning takes place within an exclusive literary or cinematic context. Rather, this approach will allow us to obtain a fuller picture of the narrative of the South African city than is possible by concentrating on one medium. It is based on the premise that narratives are ultimately produced by culture; thus these cultural constructions generate meanings, take on a significance, and assume forms that are articufations of the values, beliefs -the ideology - of the culture.' Literature and film offer specific forms for such narratives. By adopting an interdisciplinary approach which borrows insights from literary and film studies, this article attempts to make a contribution to the fledgling field of South African cultural studies.
- Full Text:
- Date Issued: 2009
Site of struggle: the Freedom Park fracas and the divisive legacy of South Africa’s Border War/Liberation Struggle
- Authors: Baines, Gary F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126954 , vital:35938 , https://doi.10.1080/02533950903076428
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
- Authors: Baines, Gary F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126954 , vital:35938 , https://doi.10.1080/02533950903076428
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
Reform in defence of sovereignty: South Africa in the UN Security Council, 2007–2008
- Authors: Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161431 , vital:40626 , https://0-doi.org.wam.seals.ac.za/10.1177/000203970904400205
- Description: After 1994, South Africa became the sine qua non of an internationalist state, willing to promote cooperation amongst a plurality of actors, believing common interests to be more important than their differences. This raised the hopes of constitutionalists, and those who believed in the expansion of a liberal democratic peace. South Africa has acted out two seemingly contradictory roles: those of a reformer and those of a conserver. By 2007–2008 she had shifted towards the latter, conservative-reformist position. Thus, South Africa's voting record at the General Assembly expressed her overriding concern to regionalise African issues and minimise the US and the West shaping political events. This brought her foreign policy into sharper relief. But while in some sense successful, it came at a price: a controversy about her surrendering her internationalism and principles on human rights for African unity and traditional sovereignty. But it also marked the arrival of South Africa in the world of international Realpolitik.
- Full Text:
- Date Issued: 2009
- Authors: Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161431 , vital:40626 , https://0-doi.org.wam.seals.ac.za/10.1177/000203970904400205
- Description: After 1994, South Africa became the sine qua non of an internationalist state, willing to promote cooperation amongst a plurality of actors, believing common interests to be more important than their differences. This raised the hopes of constitutionalists, and those who believed in the expansion of a liberal democratic peace. South Africa has acted out two seemingly contradictory roles: those of a reformer and those of a conserver. By 2007–2008 she had shifted towards the latter, conservative-reformist position. Thus, South Africa's voting record at the General Assembly expressed her overriding concern to regionalise African issues and minimise the US and the West shaping political events. This brought her foreign policy into sharper relief. But while in some sense successful, it came at a price: a controversy about her surrendering her internationalism and principles on human rights for African unity and traditional sovereignty. But it also marked the arrival of South Africa in the world of international Realpolitik.
- Full Text:
- Date Issued: 2009
The synthesis and photophysicochemical properties of low-symmetry zinc phthalocyanine analogues
- Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263397 , vital:53624 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.06.005"
- Description: The synthesis of a low-symmetry derivative, zinc mono-carboxy substituted phthalocyanine, ZnPc-COOH (4) has been reported. The photochemical and photophysical properties of ZnPc-COOH (4), ZnTMPyPc (5), ZnttbPc (6) and a previously synthesized low-symmetry derivative, ZnttbIPc (7), in various organic solvents are reported. The red-shifting of the spectra of 4 and 5 (relative to that of unsubstituted zinc phthalocyanine, ZnPc) is a function of the electron-donating sulfur-containing substituents attached to the periphery of the molecule. High triplet quantum yields (ФT) generally occur in response to substitution on the zinc phthalocyanine ring periphery. The highest ФT values and triplet lifetimes (τT) occur in DMSO for all derivatives as a result of the solvent's high viscosity. The strongly electron-withdrawing imido fused ring of ZnttbIPc (7) stabilizes it against photo-oxidative degradation relative to the other derivatives.
- Full Text:
- Date Issued: 2009
- Authors: Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263397 , vital:53624 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.06.005"
- Description: The synthesis of a low-symmetry derivative, zinc mono-carboxy substituted phthalocyanine, ZnPc-COOH (4) has been reported. The photochemical and photophysical properties of ZnPc-COOH (4), ZnTMPyPc (5), ZnttbPc (6) and a previously synthesized low-symmetry derivative, ZnttbIPc (7), in various organic solvents are reported. The red-shifting of the spectra of 4 and 5 (relative to that of unsubstituted zinc phthalocyanine, ZnPc) is a function of the electron-donating sulfur-containing substituents attached to the periphery of the molecule. High triplet quantum yields (ФT) generally occur in response to substitution on the zinc phthalocyanine ring periphery. The highest ФT values and triplet lifetimes (τT) occur in DMSO for all derivatives as a result of the solvent's high viscosity. The strongly electron-withdrawing imido fused ring of ZnttbIPc (7) stabilizes it against photo-oxidative degradation relative to the other derivatives.
- Full Text:
- Date Issued: 2009
Effect of peripheral fused ring substitution on the optical spectroscopy and electronic structure of metal phthalocyanine complexes
- Chidawanyika, Wadzanai J U, Mack, John, Shimizu, Soji, Kobayashi, Nagao, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai J U , Mack, John , Shimizu, Soji , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263353 , vital:53620 , xlink:href="https://doi.org/10.1142/S1088424609001339"
- Description: In this paper the impact of peripheral substitution with a strongly withdrawing fused ring group on the optical spectroscopy of a metal phthalocyanine complex is analyzed. We report the synthesis of [9 (or 10), 16 (or 17), 23 (or 24)-tri-tert-butylimidophthalocyaninato]zinc(II) (ZnttbIPc), which should eventually prove to be a useful precursor for forming dimeric compounds. The electronic structure is analyzed through a detailed analysis of the UV-visible absorption and magnetic circular dichroism spectra and time-dependent density functional theory calculations. Other than a marked splitting of the Q band, the spectrum is broadly similar to that of ZnPc in terms of the main π → π* electronic bands. The vibrational bands differ markedly in the Q band region when an imido group is added to ligand periphery, relative to what is observed in the case of zinc mononaphthotribenzotetraazaporphyrin (Zn3B1N) with an additional fused benzene ring. The absorption and emission spectra lack mirror symmetry as is the case with ZnPc and thus provide possible evidence for a second set of electronic origins in the Q band region arising from n → π* rather then π → π* transitions.
- Full Text:
- Date Issued: 2009
- Authors: Chidawanyika, Wadzanai J U , Mack, John , Shimizu, Soji , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263353 , vital:53620 , xlink:href="https://doi.org/10.1142/S1088424609001339"
- Description: In this paper the impact of peripheral substitution with a strongly withdrawing fused ring group on the optical spectroscopy of a metal phthalocyanine complex is analyzed. We report the synthesis of [9 (or 10), 16 (or 17), 23 (or 24)-tri-tert-butylimidophthalocyaninato]zinc(II) (ZnttbIPc), which should eventually prove to be a useful precursor for forming dimeric compounds. The electronic structure is analyzed through a detailed analysis of the UV-visible absorption and magnetic circular dichroism spectra and time-dependent density functional theory calculations. Other than a marked splitting of the Q band, the spectrum is broadly similar to that of ZnPc in terms of the main π → π* electronic bands. The vibrational bands differ markedly in the Q band region when an imido group is added to ligand periphery, relative to what is observed in the case of zinc mononaphthotribenzotetraazaporphyrin (Zn3B1N) with an additional fused benzene ring. The absorption and emission spectra lack mirror symmetry as is the case with ZnPc and thus provide possible evidence for a second set of electronic origins in the Q band region arising from n → π* rather then π → π* transitions.
- Full Text:
- Date Issued: 2009
A far from passive record Anton van Wouw: The smaller works, AE Duffey: book review
- Authors: de Jager, Maureen
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147402 , vital:38633 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC38334
- Description: Anton van Wouw : the smaller works is, as its title implies, concerned with the generally lesser-known smaller works of Dutch-born sculptor, Anton van Wouw. Using the measure of "half life-size and smaller" as a guideline, author Alexander Duffey provides a comprehensive and well-illustrated overview of the many full-length small sculptures, busts, relief panels and maquettes produced by Van Wouw between 1881 (nine years prior to his arrival in South Africa at the age of 28) and 1940. Naturalistically sculpted and generally cast in bronze, these smaller works are wide-ranging in their subject matter, depicting innocuous, commonplace scenes alongside aspects of Afrikaner history, representations of Boer and British leaders, and so-called "native studies" (p 11).
- Full Text:
- Date Issued: 2009
- Authors: de Jager, Maureen
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147402 , vital:38633 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC38334
- Description: Anton van Wouw : the smaller works is, as its title implies, concerned with the generally lesser-known smaller works of Dutch-born sculptor, Anton van Wouw. Using the measure of "half life-size and smaller" as a guideline, author Alexander Duffey provides a comprehensive and well-illustrated overview of the many full-length small sculptures, busts, relief panels and maquettes produced by Van Wouw between 1881 (nine years prior to his arrival in South Africa at the age of 28) and 1940. Naturalistically sculpted and generally cast in bronze, these smaller works are wide-ranging in their subject matter, depicting innocuous, commonplace scenes alongside aspects of Afrikaner history, representations of Boer and British leaders, and so-called "native studies" (p 11).
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- Date Issued: 2009
Language shift in Grahamstown: A case study of selected Xhosa-speakers
- Authors: De Klerk, Vivian A
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158106 , vital:40149 , https://0-doi.org.wam.seals.ac.za/10.1515/ijsl.2000.146.87
- Description: A number of scholars (Fasold 1984; Aitchison 1991; Denison 1977; Dorian 1980; Gal 1979) have examined the issue of language maintenance and shift, trying to discover why certain languages (or language variants) sometimes replace each other among some Speakers, particularly in certain domains of linguistic behaviour under some conditions or intergroup contact. This article provides an overview of the main factors that have been identified as playing an important role in influencing language shift and then reports on the relative importance of these factors in a survey that examined the experiences and attitudes of Xhosa-speaking parents who have recently chosen to send their children to English-medium schools in Grahamstown (Eastern Cape, South Africa). The research was carried out during 1998, and the project was a multifaceted quantitative and qualitative longitudinal study involving responses to a postal questionnaire sent to all non-English parents at English-medium schools in the town, and follow-up Interviews with 26 parents.
- Full Text:
- Date Issued: 2009
- Authors: De Klerk, Vivian A
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158106 , vital:40149 , https://0-doi.org.wam.seals.ac.za/10.1515/ijsl.2000.146.87
- Description: A number of scholars (Fasold 1984; Aitchison 1991; Denison 1977; Dorian 1980; Gal 1979) have examined the issue of language maintenance and shift, trying to discover why certain languages (or language variants) sometimes replace each other among some Speakers, particularly in certain domains of linguistic behaviour under some conditions or intergroup contact. This article provides an overview of the main factors that have been identified as playing an important role in influencing language shift and then reports on the relative importance of these factors in a survey that examined the experiences and attitudes of Xhosa-speaking parents who have recently chosen to send their children to English-medium schools in Grahamstown (Eastern Cape, South Africa). The research was carried out during 1998, and the project was a multifaceted quantitative and qualitative longitudinal study involving responses to a postal questionnaire sent to all non-English parents at English-medium schools in the town, and follow-up Interviews with 26 parents.
- Full Text:
- Date Issued: 2009
Factors affecting recapture rates of raggedtooth sharks Carcharias taurus tagged off the east coast of South Africa
- Dicken, Matthew L, Booth, Anthony J, Smale, Malcolm J
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124493 , vital:35618 , https://doi.10.2989/AJMS.2009.31.3.9.997
- Description: Understanding differences in the recapture rate between different tags (A-, B- and C-types), capture methods (rock-and-surf anglers, scientific divers and Natal Sharks Board protection nets) and life-history stages (juvenile and adult) is critical in evaluating the results obtained from cooperative tagging programmes (CTPs). A generalised linear modelling approach, using a log-linear model, was used to determine significant differences in the probability of recapture between these various factors using data from the Oceanographic Research Institute and Port Elizabeth Museum CTPs. Between 1984 and 2004, a total of 3 385 raggedtooth sharks Carcharias taurus was tagged by volunteers from both programmes along the east coast of South Africa. A likelihood ratio test indicated significant differences in the probability of recapture between A- and C-type and B- and C-type tags (p < 0.01), between different capture methods (p < 0.05) and between juvenile and adult sharks (p < 0.01). A comparison of recapture rates between members of the CTPs also indicated a marked variability in the performance of individual taggers. The study highlights important data-quality issues inherent in large CTPs.
- Full Text:
- Date Issued: 2010
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124493 , vital:35618 , https://doi.10.2989/AJMS.2009.31.3.9.997
- Description: Understanding differences in the recapture rate between different tags (A-, B- and C-types), capture methods (rock-and-surf anglers, scientific divers and Natal Sharks Board protection nets) and life-history stages (juvenile and adult) is critical in evaluating the results obtained from cooperative tagging programmes (CTPs). A generalised linear modelling approach, using a log-linear model, was used to determine significant differences in the probability of recapture between these various factors using data from the Oceanographic Research Institute and Port Elizabeth Museum CTPs. Between 1984 and 2004, a total of 3 385 raggedtooth sharks Carcharias taurus was tagged by volunteers from both programmes along the east coast of South Africa. A likelihood ratio test indicated significant differences in the probability of recapture between A- and C-type and B- and C-type tags (p < 0.01), between different capture methods (p < 0.05) and between juvenile and adult sharks (p < 0.01). A comparison of recapture rates between members of the CTPs also indicated a marked variability in the performance of individual taggers. The study highlights important data-quality issues inherent in large CTPs.
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- Date Issued: 2010
Understanding social learning processes in a citrus farming community of practice
- Authors: Downsborough, Linda
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386949 , vital:68191 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122819"
- Description: This paper focuses on what would traditionally be termed ‘non-formal’ learning processes in the context of a case study examining how citrus farming communities in the Patensie Valley in the Eastern Cape in South Africa were learning conservation practices. Communities of Practice theory was used to provide a conceptual framework for researching these learning interactions. Through historical and other qualitative research methods, I was able to establish that farmers in this community of practice learned mainly through responding to change and uncertainty, through forming and drawing on networks and community structures, through intergenerational learning, and through various interactions with each other. The historical research also pointed to the significance of policy and market-based changes in farmer learning, and their attachment to the land, which is shaped through historical associations with the land, and through embedded relations in farming practice cultures. The paper provides an example of how Communities of Practice theory, complemented by historical research, can be used to understand non-formal learning.
- Full Text:
- Date Issued: 2009
- Authors: Downsborough, Linda
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386949 , vital:68191 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122819"
- Description: This paper focuses on what would traditionally be termed ‘non-formal’ learning processes in the context of a case study examining how citrus farming communities in the Patensie Valley in the Eastern Cape in South Africa were learning conservation practices. Communities of Practice theory was used to provide a conceptual framework for researching these learning interactions. Through historical and other qualitative research methods, I was able to establish that farmers in this community of practice learned mainly through responding to change and uncertainty, through forming and drawing on networks and community structures, through intergenerational learning, and through various interactions with each other. The historical research also pointed to the significance of policy and market-based changes in farmer learning, and their attachment to the land, which is shaped through historical associations with the land, and through embedded relations in farming practice cultures. The paper provides an example of how Communities of Practice theory, complemented by historical research, can be used to understand non-formal learning.
- Full Text:
- Date Issued: 2009
Applicability of the REALM health literacy test to an English second-language South African population:
- Dowse, Roslind, Lecoko, Motlalepule L E, Ehlers, Martina S
- Authors: Dowse, Roslind , Lecoko, Motlalepule L E , Ehlers, Martina S
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156798 , vital:40051 , https://doi.org/10.1007/s11096-010-9392-y
- Description: Objective and setting. To investigate health literacy in an English second language population using the REALM test, to evaluate its appropriateness and to compare health literacy between four different education categories. Setting Primary healthcare clinics and participant homes in Grahamstown, South Africa.
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- Date Issued: 2010
- Authors: Dowse, Roslind , Lecoko, Motlalepule L E , Ehlers, Martina S
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156798 , vital:40051 , https://doi.org/10.1007/s11096-010-9392-y
- Description: Objective and setting. To investigate health literacy in an English second language population using the REALM test, to evaluate its appropriateness and to compare health literacy between four different education categories. Setting Primary healthcare clinics and participant homes in Grahamstown, South Africa.
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- Date Issued: 2010
Mobile monitors: protecting the will of the people
- Authors: Dugmore, Harry
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159377 , vital:40292 , https://hdl.handle.net/10520/EJC139912
- Description: The use of mobile phone technology in recent African elections has empowered citizens, allowing them to put in place the checks and balances needed to make elections freer and fairer in Africa - and elsewhere in the world, writes Harry Dugmore.
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- Date Issued: 2009
- Authors: Dugmore, Harry
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159377 , vital:40292 , https://hdl.handle.net/10520/EJC139912
- Description: The use of mobile phone technology in recent African elections has empowered citizens, allowing them to put in place the checks and balances needed to make elections freer and fairer in Africa - and elsewhere in the world, writes Harry Dugmore.
- Full Text:
- Date Issued: 2009
Meeting democracy’s challenge developments:
- Authors: Dugmore, Harry
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159389 , vital:40293 , https://hdl.handle.net/10520/EJC139935
- Description: In a context of declining public participation, can mobile phone technology and 'new media' be used to involve more people in local decision-making, asks Harry Dug more in this exploration of the implications of mobile communication on journalism in the developing world.
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- Date Issued: 2009
- Authors: Dugmore, Harry
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159389 , vital:40293 , https://hdl.handle.net/10520/EJC139935
- Description: In a context of declining public participation, can mobile phone technology and 'new media' be used to involve more people in local decision-making, asks Harry Dug more in this exploration of the implications of mobile communication on journalism in the developing world.
- Full Text:
- Date Issued: 2009
The synthesis and photophysicochemical behaviour of novel water-soluble cationic indium (III) phthalocyanine
- Durmus, Mahmut, Erdoğmuş, Ali, Ogunsipe, Abimbola, Nyokong, Tebello
- Authors: Durmus, Mahmut , Erdoğmuş, Ali , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263419 , vital:53626 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.01.008"
- Description: The syntheses and characterization of 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) and quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) are described. The ground state electronic absorption spectra, photophysics and photochemistry of both dyes in DMSO as well as that of the quaternized compound in aqueous solution are also presented. A comparison of the photophysical and photochemical parameters of the two dyes revealed that quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) was a better photosensitizer than its unquaternized counterpart. The quantum yield values of fluorescence (ΦF), triplet state formation (ΦT) and singlet oxygen formation (ΦΔ) for the cationic dye were found to be 0.03, 0.68 and 0.66 respectively in DMSO; these values were higher than those for 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III), which exhibited values of 0.02, 0.66 and 0.63, respectively in DMSO. The values for the cationic dye in aq. solution were 0.02, 0.59 and 0.56 respectively, suggesting that the water-soluble quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) offers potential as a photosensitizer in photodynamic therapy treatment.
- Full Text:
- Date Issued: 2009
- Authors: Durmus, Mahmut , Erdoğmuş, Ali , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263419 , vital:53626 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.01.008"
- Description: The syntheses and characterization of 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) and quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) are described. The ground state electronic absorption spectra, photophysics and photochemistry of both dyes in DMSO as well as that of the quaternized compound in aqueous solution are also presented. A comparison of the photophysical and photochemical parameters of the two dyes revealed that quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) was a better photosensitizer than its unquaternized counterpart. The quantum yield values of fluorescence (ΦF), triplet state formation (ΦT) and singlet oxygen formation (ΦΔ) for the cationic dye were found to be 0.03, 0.68 and 0.66 respectively in DMSO; these values were higher than those for 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III), which exhibited values of 0.02, 0.66 and 0.63, respectively in DMSO. The values for the cationic dye in aq. solution were 0.02, 0.59 and 0.56 respectively, suggesting that the water-soluble quaternized 2,3-octakis-(3-pyridyloxyphthalocyaninato) indium(III) offers potential as a photosensitizer in photodynamic therapy treatment.
- Full Text:
- Date Issued: 2009
Synthesis, photophysics and photochemistry of novel tetra (quinoxalinyl) phthalocyaninato zinc (II) complexes
- Erdoğmuş, Ali, Ogunsipe, Abimbola, Nyokong, Tebello
- Authors: Erdoğmuş, Ali , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263441 , vital:53628 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.04.007"
- Description: The syntheses and spectral, photophysical and photochemical properties of some zinc phthalocyanine derivatives – {2, (3)-tetra(quinoxalinyl)phthalocyaninato zinc(II), (β-ZnPc) and 1, (4)-tetra(quinoxalinyl)phthalocyaninato zinc(II), (α-ZnPc)} – are presented. The β-substituted complex is more fluorescent and exhibits lower tendencies to undergo intersystem crossing than its α-substituted counterpart, as judged by the former's higher fluorescence quantum yield (ΦF) and lower triplet quantum yield (ΦT) than the latter's in three solvents (DMSO, DMF and toluene). Singlet oxygen quantum yield (ΦΔ) values show the same trends as ΦT values. The differences in the spectral and photophysical properties of α-ZnPc and β-ZnPc are partly attributed to greater molecular distortions in the former. Studies of the interaction of the triplet states of α-ZnPc and β-ZnPc with triplet oxygen showed that α-ZnPc is more vulnerable to oxygen quenching than β-ZnPc. Also, the smallest quenching rate constants were observed in DMSO, which is attributed to the higher viscosity of DMSO than DMF and toluene.
- Full Text:
- Date Issued: 2009
- Authors: Erdoğmuş, Ali , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263441 , vital:53628 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.04.007"
- Description: The syntheses and spectral, photophysical and photochemical properties of some zinc phthalocyanine derivatives – {2, (3)-tetra(quinoxalinyl)phthalocyaninato zinc(II), (β-ZnPc) and 1, (4)-tetra(quinoxalinyl)phthalocyaninato zinc(II), (α-ZnPc)} – are presented. The β-substituted complex is more fluorescent and exhibits lower tendencies to undergo intersystem crossing than its α-substituted counterpart, as judged by the former's higher fluorescence quantum yield (ΦF) and lower triplet quantum yield (ΦT) than the latter's in three solvents (DMSO, DMF and toluene). Singlet oxygen quantum yield (ΦΔ) values show the same trends as ΦT values. The differences in the spectral and photophysical properties of α-ZnPc and β-ZnPc are partly attributed to greater molecular distortions in the former. Studies of the interaction of the triplet states of α-ZnPc and β-ZnPc with triplet oxygen showed that α-ZnPc is more vulnerable to oxygen quenching than β-ZnPc. Also, the smallest quenching rate constants were observed in DMSO, which is attributed to the higher viscosity of DMSO than DMF and toluene.
- Full Text:
- Date Issued: 2009