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Defining our purposes and roles and meeting our challenges

- Badat, Saleem, Higher Education South Africa (Organization)

Authors: Badat, Saleem , Higher Education South Africa (Organization)
Date: 2006-08 , 2014-06-12
Subjects: Universities and colleges -- South Africa
Language: English
Type: Text
Identifier: vital:7606 , http://hdl.handle.net/10962/d1011803
Description: This paper briefly articulates the social purposes and roles of universities; outlines some of the key strengths and achievements of South African universities post-1994, and; identifies the critical issues and challenges that confront our universities in relation to their core social purposes and roles.
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Date Issued: 2006-08

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Effects of ZnO nanohexagons and nanorods on the fluorescence behavior of metallophthalocyanines

- D’Souza, Sarah, Moeno, Sharon, Nyokong, Tebello

Authors: D’Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
Language: English
Type: Article
Identifier: vital:7263 , http://hdl.handle.net/10962/d1020272
Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.09.012
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Exploring the political geoecology of African Drainage Basins

- Rowntree, Kate M

Authors: Rowntree, Kate M
Date: 2008-04
Language: English
Type: Text
Identifier: vital:580 , http://hdl.handle.net/10962/d1018873 , Transcript of Inaugural lecture August 2007
Description: [From the text] Many people in Africa rely directly on their natural ecosystems for their livelihoods. A key driver of these ecosystems is water, which in Africa has a high spatial and temporal variability. Water comes from rainfall, but the availability of that water depends on the way that it is processed through the landscape unit known as a drainage basin. Drainage basins are the "home" of rivers; rivers which sustain ecosystems and their dependents (human society). Humans and ecosystems cannot live apart from one another, but the relationship can be exploitative and degrading, or harmonious and protective. Throughout history human activity has been subject to direct controls and indirect pressures subjected by the larger society, through political, economic and cultural forces that are often intertwined. Rivers are especially sensitive to the geography of this relationship. Being longitudinal ecosystems that transfer water and other materials from the source of the river to the oceans, activities in upstream areas have a direct impact on downstream areas. To explore these socio-ecological relationships within the context of an African drainage basin I have developed the concept of political geoecology that is explored in this address.
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Date Issued: 2008-04

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Mechanisms generating biological diversity in the genus Platypleura Amyot & Serville, 1843 (Hemiptera: Cicadidae) in southern Africa: implications of a preliminary molecular phylogeny

- Villet, Martin H, Barker, Nigel P, Lunt, Nicola

Authors: Villet, Martin H , Barker, Nigel P , Lunt, Nicola
Date: 2004
Language: English
Type: Article
Identifier: vital:6554 , http://hdl.handle.net/10962/d1006012
Description: Truly understanding biological diversity requires a move from descriptive studies to mechanistic interpretations based on comparative biology and a thorough recognition of the natural history of the focal organisms. A useful step in such comparative studies is the generation of a phylogeny, so that one can assess the phylogenetic independence of the focal taxa and trace the evolutionary significance of their characteristics. As a preliminary to such studies on the platypleurine cicada genus Platypleura, we sequenced 498 bases of the cytochrome oxidase I (COI) gene from thirteen African species. To circumvent problems with outgroup selection, we also included sequences from representatives of the platypleurine genera Brevisiana, Capcicada, Munza, Oxypleura, Severiana, and Systophlochius, all of the subtribe Platypleuriti, and two species of the genus Ugada, of the subtribe Hainanosemiiti. The resulting phylogenies support the synonymization of the monotypic genus Systophlochius with the widespread, speciose genus Platypleura; confirm the placement of Platypleura sp. 7 in that genus; and confirm the independence of Capcicada and Platypleura. Although the preliminary phylogeny lacks strong support at many nodes, it suggests that three radiations of Platypleura have occurred in southern Africa and that there was progressive southward speciation of these radiations. A novel modification of the ancestral area analysis further suggests that the group has an ancestral association with acacias but there were five independent speciation events associated with host- switching. These insights can be summarized by a general hypothesis that the mechanisms underlying platypleurine biodiversity in southern Africa involve two ancient vicariance events and subsequent speciation by vicariance, switching of plant associations, and changes of habitat preferences. We offer this example to illustrate how analysis of preliminary data can help to generate hypotheticodeductive research hypotheses, to provoke interest in testing these hypotheses, and to illustrate the utility of phylogenies beyond systematics.
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Date Issued: 2004

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Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique

- Zongo, S, Sanusi, Kayode, Britton, Jonathan, Mthunzi, P, Nyokong, Tebello, Maaza, M, Sahraoui, B

Authors: Zongo, S , Sanusi, Kayode , Britton, Jonathan , Mthunzi, P , Nyokong, Tebello , Maaza, M , Sahraoui, B
Date: 2015
Language: English
Type: Article
Identifier: vital:7261 , http://hdl.handle.net/10962/d1020270
Description: We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532 nm with 10 ns, 10 Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10−10 m/W, 10−9 esu and 10−32 esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.04.031
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Date Issued: 2015

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