The synthesis, photophysical and dielectric properties of ball-type dinuclear zinc phthalocyanine
- Authors: Canlıca, Mevlüde , Altındal, Ahmet , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243532 , vital:51161 , xlink:href="https://doi.org/10.1142/S1088424612500836"
- Description: The synthesis of ball-type dinuclear Zn(II) phthalocyanine containing four 4,4′-(9H-fluorene-9,9-diyl)diphenol substituents at the non-peripheral position is presented. The structure of the synthesized compound was characterized using elemental analyzes, and UV-vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF value was 0.16 and ΦT value was 0.72. The complex showed reasonably long triplet lifetimes with τT 7210 μs in DMSO. The frequency and temperature dependence of the dielectric properties of ZnPc were also investigated in the frequency range of 40–105 Hz and in the temperature range of 300–440 °K. It has been observed that both dielectric constant ε′ and dielectric loss ε″ decrease with the rise in frequency as they increase with the rise in temperature. The decrease in ε′ with increasing frequency is attributed to the fact that as the frequency increases, the polarizability contribution from orientation sources decreases and finally disappears.
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- Date Issued: 2012
The use of hot and cold high pressure homogenization to enhance the loading capacity and encapsulation efficiency of nanostructured lipid carriers for the hydrophilic antiretroviral drug, didanosine for potential administration to paediatric patients
- Authors: Kasongo, Kasongo W , Müller, Rainer H , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184087 , vital:44170 , xlink:href="https://doi.org/10.3109/10837450.2010.542163"
- Description: A major obstacle to the application of nanostructured lipid carriers (NLCs) as carriers for hydrophilic drugs is the limited loading capacity (LC) and encapsulation efficiency (EE) of NLCs for these molecules. The purpose of this research was to design and implement a strategy to enhance the LC and EE of NLCs for the hydrophilic drug, didanosine (DDI). DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid was reduced gradually using hot high pressure homogenization (HPH). The product obtained thereafter was added to Precirol® ATO 5 and the hot mixture was immediately dried using liquid nitrogen. The dried materials were then ground and passed through a 200 μm sieve and the solid lipid particles were dispersed in a surfactant solution and subsequently used to manufacture DDI-loaded NLCs using cold HPH. The LC and EE of NLCs for DDI manufactured using the new strategy were 3.39 ± 0.63% and 51.58 ± 1.31%, respectively, compared to 0.079 ± 0.001% and 32.45 ± 0.08%, respectively, obtained when DDI-loaded NLCs were produced using conventional hot HPH. The enhanced LC and EE for DDI make NLCs a potential technology for the oral administration of DDI to paediatric patients.
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- Date Issued: 2012
The use of response surface methodology in the evaluation of captopril microparticles manufactured using an oil in oil solvent evaporation technique
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184221 , vital:44191 , xlink:href="https://doi.org/10.3109/02652048.2011.629744"
- Description: Captopril (CPT) microparticles were manufactured by solvent evaporation using acetone (dispersion phase) and liquid paraffin (manufacturing phase) with Eudragit® and Methocel® as coat materials. Design of experiments and response surface methodology (RSM) approaches were used to optimize the process. The microparticles were characterized based on the percent of drug released and yield, microcapsule size, entrapment efficiency and Hausner ratio. Differential scanning calorimetry (DSC), Infrared (IR) spectroscopy, scanning electron microscopy (SEM) and in vitro dissolution studies were conducted. The microcapsules were spherical, free-flowing and IR and DSC thermograms revealed that CPT was stable. The percent drug released was investigated with respect to Eudragit® RS and Methocel® K100M, Methocel® K15M concentrations and homogenizing speed. The optimal conditions for microencapsulation were 1.12 g Eudragit® RS, 0.67 g Methocel® K100M and 0.39 g Methocel® K15M at a homogenizing speed of 1643 rpm and 89% CPT was released. The value of RSM-mediated microencapsulation of CPT was elucidated.
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- Date Issued: 2012
The use of response surface methodology to evaluate the impact of level 2 SUPAC–IR changes on the in vitro release of metronidazole and ranitidine from a fixed-dose combination tablet
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
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- Date Issued: 2012
Three tales of Theal: biography, history and ethnography on the Eastern Frontier
- Authors: Naidu, Samantha
- Date: 2012
- Language: English
- Type: Article , text
- Identifier: vital:24529 , http://hdl.handle.net/10962/36216 , https://www.jstor.org/stable/23267873?seq=1#page_scan_tab_contents , https://orcid.org/0000-0001-9456-8657
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- Date Issued: 2012
Towards empowering learners in a democratic mathematics classroom: to what extent are teachers' listening orientations conducive to and respectful of learners' thinking?
- Authors: Mhlolo, Michael K , Schäfer, Marc
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140882 , vital:37926 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC129235
- Description: In an effort to make education accessible, to 'heal the divisions of the past and establish a society based on democratic values', the South African Department of Education claims that a series of mathematics reforms that has so far been introduced is underpinned by the principles of 'social justice, fundamental human rights and inclusivity'. Critics however argue that the system has remained 'undemocratic' in that those groups of learners who were supposed to be 'healed' continue to underperform and hence be disempowered. In this study, we conceptualised a democratic and mathematically empowering classroom as one that is consistent with the principle of inclusivity and in which a hermeneutic listening orientation towards teaching promotes such a democratic and mathematically empowering learning environment. We then worked with three different orientations teachers might have towards listening in the mathematics classroom: evaluative, interpretive and hermeneutic. We then used these orientations to analyse 20 video-recorded lessons with a specific focus on learners' unexpected contributions and how teachers listened and responded to such contributions. The results were consistent with the literature, which shows that teachers tend to dismiss learners' ways of thinking by imposing their own formalised constructions.
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- Date Issued: 2012
Toxic effect of herbicides used for water hyacinth control on two insects released for its biological control in South Africa
- Authors: Hill, Martin P
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69960 , vital:29601 , https://doi.org/10.1080/09583157.2012.725825
- Description: The integrated control of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae) has become necessary in South Africa, as biological control alone is perceived to be too slow in controlling the weed. In total, seven insect biological control agents have been released on water hyacinth in South Africa. At the same time, herbicides are applied by the water authorities in areas where the weed continues to be troublesome. This study investigated the assumption that the two control methods are compatible by testing the direct toxicity of a range of herbicide formulations and surfactants on two of the biological control agents released against water hyacinth, the weevil, Neochetina eichhorniae Warner (Coleoptera: Curculionidae) and the water hyacinth mirid,Eccritotarsus catarinensis (Carvalho) (Hemiptera: Miridae). A number of the formulations used resulted in significant mortality of the mirid and the weevil. Products containing 2,4-D amine and diquat as active ingredients caused higher mortality of both agents (up to 80% for the mirid) than formulations containing glyphosate. Furthermore, when surfactants were added to enhance herbicide efficiency, it resulted in increased toxicity to the insects. We recommend that glyphosate formulations should be used in integrated control programmes, and that surfactants be avoided in order to reduce the toxic nature of spray formulations to the insect biological control agents released against water hyacinth.
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- Date Issued: 2012
Trauma, (Mis) Perception and Memory in Uwem Akpan's ‘Fattening for Gabon’:
- Authors: Njovane, Thandokazi
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142726 , vital:38111 , https://doi.org/10.1080/00138398.2012.731303
- Description: It is a generally accepted principle in contemporary poststructuralist literary studies that language can only ever partially succeed in signifying that which it purports to signify. Where the profoundly dislocating experience of trauma is concerned, language loses even this partial success, and the victim of psychic violence is forced to resort to silence, a silence which is all the more expressive precisely because it overwhelms language. Thus, trauma fiction reveals what Steiner refers to as ‘the revaluation of silence’ which emphasises ‘the conceit of the word unspoken’ (67). Uwem Akpan's short story, ‘Fattening for Gabon’, from his collection Say You're One of Them (2008), is concerned with the culpability of socio-economic structures in giving rise to and perpetuating trauma in children. This paper will examine the retrospective narration of the protagonist by paying particular attention to the motif of memory. A discussion of the painful ambivalence of the experience and textualization of trauma, as conveyed through the story's use of silence and the disruption of the conventional bildung typical of narratives of remembrance, will form a substantial part of the paper.
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- Date Issued: 2012
Trends in the optical and redox properties of tetraphenyltetraphenanthroporphyrins
- Authors: Mack, John , Lobb, Kevin , Nyokong, Tebello , Shen, Zhen , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245809 , vital:51407 , xlink:href="https://doi.org/10.1142/S1088424612500885"
- Description: The results of TD-DFT calculations for a series of tetraaryltetraphenanthroporphyrins containing para-substituents with differing electron donating and accepting properties are compared to the observed optical and redox properties and Michl's perimeter model is used as a conceptual framework for analyzing the results.
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- Date Issued: 2012
Troubling White Englishness in South Africa:
- Authors: Garman, Anthea
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/159756 , vital:40340 , ISBN 978-1-84888-105-1
- Description: To be white in Africa is to be part of a minority - but a very powerful minority. To be white in South Africa is to be implicated and complicit in historical dispossession and disenfranchisement. However, in post-apartheid South Africa, whiteness is no longer the invisible condition of the default human being, a condition to which all other humans must aspire. In fact, to be white is suddenly to be very visibly Other to the black African majority who are increasingly shaping the social landscape in ways that undermine the trajectories of both the colonial project and the apartheid project in this country.
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- Date Issued: 2012
Understanding student performance in a large class
- Authors: Snowball, Jeanette D , Boughey, Chrissie
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71333 , vital:29834 , https://www.tandfonline.com/doi/abs/10.1080/14703297.2012.677658
- Description: Across the world, university teachers are increasingly being required to engage with diversity in the classes they teach. Using the data from a large Economics 1 class at a South African university, this attempts to understand the effects of diversity on chances of success and how assessment can impact on this. By demonstrating how theory can be used to understand results, the paper aims to encourage university teachers to adopt proactive strategies in managing diversity, rather than simply explaining it using student characteristics.
- Full Text: false
- Date Issued: 2012
Unquenched fluorescence lifetime for β-phenylthio substituted zinc phthalocyanine upon conjugation to gold nanoparticles
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
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- Date Issued: 2012
Violence and the cultural logics of pain: representations of sexuality in the work of Nicholas Hlobo and Zanele Muholi
- Authors: Makhubu, Nomusa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147814 , vital:38675 , https://0-doi.org.wam.seals.ac.za/10.1080/02560046.2012.723843
- Description: Nicholas Hlobo and Zanele Muholi have raised critical issues regarding sexual identity in patriarchal contexts since they premiered at the Michael Stevenson Gallery in 2005. Nicholas Hlobo, a sculptor and performance artist, and Zanele Muholi, a photographer and activist, explore different ways of representing sexuality – in particular, homosexuality. Hlobo investigates notions of masculinity and the practice of circumcision, while Muholi documents the existence of transgender and homosexuality in township spaces (her recent work expands to various other spaces). This article focuses on the roles that violence plays in the sexual politics represented in Hlobo and Muholi’s work.
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- Date Issued: 2012
Voices from the forest: celebrating nature and culture in Xhosaland
- Authors: Dold, Anthony P , Cocks, Michelle L
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141427 , vital:37971 , ISBN 9781431402991 , https://www.amazon.com/Voices-Forest-Celebrating-Culture-Xhosaland/dp/1431402990
- Description: The link between people and nature is explored in this fascinating book, revealing how plants, animals, and landscapes are profoundly reflected in South Africa’s Xhosa language, stories, poetry, religious rituals, healing practices, and everyday customs. While the South African landscape has for centuries been molded and manipulated by humans, the country and its plants and animals have in turn influenced South Africans’ cultural and spiritual development. Based on 10 years of research, it consists of unique photographs that portray how both contemporary rural and urban South Africans still find great value in nature. A fresh, positive approach to biodiversity conservation, this volume serves as a guide to sustainable practices in the future.
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- Date Issued: 2012
Vulindela!: opening the gates of journalism
- Authors: Schoon, Alette
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159528 , vital:40305 , https://hdl.handle.net/10520/EJC134094
- Description: A group of teenagers crowd together in a hall in Fingo Village, Grahamstown. They listen with rapt attention as one of them shares his anger at being short-changed in terms of his own future - teachers are absent for two out of every six school periods, compromising his chances of education.
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- Date Issued: 2012
Welcome Address of the Vice‐Chancellor of Rhodes University, Dr Saleem Badat, to First‐Year students
- Authors: Badat, Saleem
- Date: 2012
- Language: English
- Type: text
- Identifier: vital:7592 , http://hdl.handle.net/10962/d1006583
- Description: From introduction: Our first purpose is to produce knowledge, so that we can better understand our natural and social worlds and also enrich our scientific and cultural heritage. The second purpose of a university is to disseminate knowledge and to develop critical and creative minds. Our goals, yours and ours, must be for you to think imaginatively, ‘effectively and critically;’ to ‘achieve depth in some field of knowledge;’ to appreciate how we ‘gain knowledge and understanding of the universe, of society, and of ourselves;’ to have ‘a broad knowledge of other cultures and other times;’ to critique ideas and views and construct alternatives, and to communicate cogently, orally and in writing. Our final purpose as a university is to undertake community engagement, whether this is as part of academic courses or your voluntary participation in community projects organized by our Community Engagement Office.
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- Date Issued: 2012
Western alumnae influencing the world
- Authors: Steyaert, Marcia
- Date: 2012
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7168 , http://hdl.handle.net/10962/d1006069 , Nyokong, Tebello
- Description: In September 2011, IT News Africa, named two Western alumnae, Uche Eze, HBA'06, and Tebello Nyokong, PhD1987 (Chemistry) in their list of top 10 most influential women in science and technology in Africa. Nyokong is a professor of medicinal chemistry and nanotechnology at Rhodes University and is recognized as one of the top three publishing scientists in South Africa.
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- Date Issued: 2012
What's been built in twenty years?: SADC and Southern Africa's political and regional security culture
- Authors: Bischoff, Paul, 1954-
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161498 , vital:40633
- Description: The sense of region in Southern Africa is based on nationalism and its struggles for national liberation. Unusually, the norms of smaller states initially shaped the region's scope and culture of interaction. First and foremost, cooperation happened in the area of security, an initial focus being to uphold the independence and sovereignty of the state in the face of challenges from apartheid South Africa. As such, rather atypically, intergovernmental security cooperation preceded broad based economic cooperation. This has meant that security and development have remained largely de-linked and this has helped discourage implementing a society or human rights centred approach to security. Cooperation has been made more difficult by disparate political systems with divergent values, cultures, agendas and sensibilities. As such, regionalism reinforces nationalism to the exclusion of development or wider notions of political and social security. The region amounts to a security regime with only a patchy record in advancing security. Therefore, in the face of developmental challenges and unless a degree of strategic coherence along political and policy fronts is reached, after 20 years of SADC the endeavour to institutionalise security in conventional state-centred ways amounts to a scenario of diminishing returns.
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- Date Issued: 2012
Where angels fear to tread: online peer-assessment in a large first-year class
- Authors: Mostert, Markus , Snowball, Jeanette D
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69289 , vital:29480 , https://doi.org/10.1080/02602938.2012.683770
- Description: In the context of widening participation, large classes and increased diversity, assessment of student learning is becoming increasingly problematic in that providing formative feedback aimed at developing student writing proves to be particularly laborious. Although the potential value of peer assessment has been well documented in the literature, the associated administrative burden, also in relation to managing anonymity and intellectual ownership, makes this option less attractive, particularly in large classes. A potential solution involves the use of information and communication technologies to automate the logistics associated with peer assessment in a time-efficient way. However, uptake of such systems in the higher education community is limited, and research in this area is only beginning. This case study reports on the use of the Moodle Workshop module for formative peer assessment of students’ individual work in a first-year introductory macro-economics class of over 800 students. Data were collected through an end-of-course evaluation survey of students. The study found that using the feature-rich Workshop module not only addressed many of the practical challenges associated with paper-based peer assessments, but also provided a range of additional options for enhancing validity and reliability of peer assessments that would not be possible with paper-based systems.
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- Date Issued: 2012
White anti-racism in post-apartheid South Africa:
- Authors: Matthews, Sally
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142361 , vital:38073 , DOI: 10.1080/02589346.2012.683938
- Description: South Africans today live not only with the memory of the racial injustices of the past, but also with present injustices that are a consequence of that past. How should white South Africans live with these past and present injustices? On recognition of the racial injustices of the past and of the continuation of forms of white privilege today, involvement in ongoing anti-racist struggles seems to be an appropriate way for white South Africans to respond to past and present injustices. However, some discussions of the way in which white privilege operates and is perpetuated in post-segregationist societies suggest the need for caution with regard to white involvement in anti-racist struggles, arguing that some of the ways in which white people involve themselves in apparently anti-racist work actually result in the perpetuation rather than the erosion of white privilege. This article explores concerns about the intractability of white privilege while also ultimately defending the appropriateness of white involvement in anti-racist struggles.
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- Date Issued: 2012