Evaluation of the in vitro differential protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (NLCs) for potential targeting to the brain
- Authors: Kasongo, Kasongo W , Jansch, Mirko , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184035 , vital:44160 , xlink:href="https://doi.org/10.3109/08982104.2010.539186"
- Description: The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol® ATO 5 and Transcutol® HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol® HS 15 alone or with a ternary surfactant system consisting of Solutol® HS 15, Tween® 80, and Lutrol® F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween® 80 and Lutrol® F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween® 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol® HS 15–stabilized nanoparticles may also achieve a similar purpose.
- Full Text:
- Date Issued: 2011
Formation, surface characterization, and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese, iron, and cobalt benzylthio phthalocyanine complexes
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
Formulation development and in vitro evaluation of didanosine-loaded nanostructured lipid carriers for the potential treatment of AIDS dementia complex
- Authors: Wa Kasongo, Kasongo , Shegokar, Ranjita , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184210 , vital:44190 , xlink:href="https://doi.org/10.3109/03639045.2010.516264"
- Description: The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol ® ATO 5 and Transcutol ® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from −18.4 to −11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.
- Full Text:
- Date Issued: 2011
Going against the tide: seeking regulations for private military/security companies in a globalized world
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128822 , vital:36163 , https://hdl.handle.net/10520/EJC85398
- Description: This article discusses the role of privatization of security in Africa, but its focus is on private military and security companies (PMSCs). The article proceeds on the basis that there is need for effective regulatory frameworks for PMSCs that operate in conflict zones of Africa. Thus, it begins by appraising the existing normative standards at the international, regional and domestic level that apply to these companies, and thereafter, identifies their shortcomings in light of the prevailing security conditions within the continent. The article then posits broad theoretical imperatives for designing a more effective regulatory framework for PMSCs and concludes by proposing the establishment an overarching continental regime constructed on the basis of the suggested imperatives.
- Full Text: false
- Date Issued: 2011
Heritage–A conceptually evolving and dissonant phenomenon: Implications for heritage management and education practices in post-colonial Southern Africa
- Authors: Zazu, Clayton
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387208 , vital:68215 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122250"
- Description: This conceptual paper is based on experiences and insights which have emerged from my quest to develop a conceptual framework for working with the term ‘heritage’ within an education for sustainable development study that I am currently conducting. Of specific interest to me, and having potential to improve the relevance and quality of heritage education in southern Africa, given the region’s inherent cultural diversity and colonial history, is the need for ‘heritage construct inclusivity’ within the processes constituting heritage education practices. Working around this broad research goal, I therefore needed to be clear about what I mean or refer to as heritage. I realised, however, how elusive and conceptually problematic the term ‘heritage’ is. I therefore, drawing from literature and experiences gained during field observations and focus group interviews, came up with the idea of working with three viewpoints of heritage. Drawing on real life cases I argue that current heritage management and education practices’ failure to recognise and respect the evolving, interconnectedness and multi layered nature of heritage, partly explain the same practices’ lack of relevance and agency to enhance the sustainable management of local heritage resources. I also suggest a few ideas which heritage educators in the context of post-colonial southern Africa may need to consider in their everyday heritage education practices. I also introduce the notion of conceptualising heritage as ‘cultural landscapes’, within which the evolving, dissonant and interconnected nature of heritage, and associated heritage constructs, may be reconciled.
- Full Text:
- Date Issued: 2011
Hierarchical spatial organization and prioritization of wetlands: a conceptual model for wetland rehabilitation in South Africa
- Authors: Sieben, E J J , Ellery, William F N , Kotze, Donovan C , Rountree, M
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144399 , vital:38342 , DOI: 10.1007/s11273-011-9212-8
- Description: Wetland rehabilitation planning needs to take into account many different aspects of the wetland and its context. In South Africa, much emphasis is placed on the delivery of ecosystem services, poverty relief and skills development for those involved in labour-intensive rehabilitation measures. A framework is presented that facilitates decision-making with regards to wetland rehabilitation planning. This starts with prioritizing which wetlands need attention within a catchment. This is followed by decisions regarding which rehabilitation measures would be effective in improving certain ecosystem services based upon the aims of rehabilitation and the social context of the surrounding catchment.
- Full Text:
- Date Issued: 2011
High Speed Lexical Classification of Malicious URLs
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428055 , vital:72483 , https://www.researchgate.net/profile/Barry-Ir-win/publication/326225046_High_Speed_Lexical_Classification_of_Malicious_URLs/links/5b3f20acaca27207851c60f9/High-Speed-Lexical-Classification-of-Malicious-URLs.pdf
- Description: It has been shown in recent research that it is possible to identify malicious URLs through lexi-cal analysis of their URL structures alone. Lightweight algorithms are defined as methods by which URLs are analyzed that do not use external sources of information such as WHOIS lookups, blacklist lookups and content analysis. These parameters include URL length, number of delimiters as well as the number of traversals through the directory structure and are used throughout much of the research in the paradigm of lightweight classification. Methods which include external sources of information are often called fully featured classifications and have been shown to be only slightly more effective than a purely lexical analysis when considering both false-positives and falsenegatives. This distinction allows these algorithms to be run client side without the introduction of additional latency, but still providing a high level of accuracy through the use of modern techniques in training classifiers. Both AROW and CW classifier update methods will be used as prototype implementations and their effectiveness will be com-pared to fully featured analysis results. These methods are selected because they are able to train on any labeled data, including instances in which their prediction is correct, allowing them to build a confidence in specific lexical features.
- Full Text:
- Date Issued: 2011
Hsp90α/β associates with the GSK3β/axin1/phospho-β-catenin complex in the human MCF-7 epithelial breast cancer model:
- Authors: Cooper, Leanne C , Prinsloo, Earl , Edkins, Adrienne L , Blatch, Gregory L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165096 , vital:41208 , DOI: 10.1016/j.bbrc.2011.08.136
- Description: Hsp90α/β, the signal transduction chaperone, maintains intracellular communication in normal, stem, and cancer cells. The well characterised association of Hsp90α/β with its client kinases form the framework of multiple signalling networks. GSK3β, a known Hsp90α/β client, mediates β-catenin phosphorylation as part of a cytoplasmic destruction complex which targets phospho-β-catenin to the 26S proteasome. The canonical Wnt/β-catenin pathway promotes stem cell self-renewal as well as oncogenesis. The degree of Hsp90α/β involvement in Wnt/β-catenin signalling needs clarification. Here, we describe the association of Hsp90α/β with GSK3β, β-catenin, phospho-β-catenin and the molecular scaffold, axin1, in the human MCF-7 epithelial breast cancer cell model using selective inhibition of Hsp90α/β, confocal laser scanning microscopy and immunoprecipitation. Our findings suggest that Hsp90α/β modulates the phosphorylation of β-catenin by interaction in common complex with GSK3β/axin1/β-catenin.
- Full Text:
- Date Issued: 2011
Human DNAJ in cancer and stem cells:
- Authors: Sterrenberg, Jason N , Edkins, Adrienne L , Blatch, Gregory L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165118 , vital:41210 , DOI: 10.1016/j.canlet.2011.08.019
- Description: The heat shock protein 40 kDa (HSP40/DNAJ) co-chaperones constitute the largest and most diverse sub-group of the heat shock protein (HSP) family. DNAJ are widely accepted as regulators of HSP70 function, but also have roles as co-chaperones for the HSP90 chaperone machine, and a growing number of biological functions that may be independent of either of these chaperones. The DNAJ proteins are differentially expressed in human tissues and demonstrate the capacity to function to both promote and suppress cancer development by acting as chaperones for tumour suppressors or oncoproteins. We review the current literature on the function and expression of DNAJ in cancer, stem cells and cancer stem cells. Combining data from gene expression, proteomics and studies in other systems, we propose that DNAJ will be key regulators of cancer, stem cell and possibly cancer stem cell function. The diversity of DNAJ and their assorted roles in a range of biological functions means that selected DNAJ, provided there is limited redundancy and that a specific link to malignancy can be established, may yet provide an attractive target for specific and selective drug design for the development of anti-cancer treatments.
- Full Text:
- Date Issued: 2011
In service to the law: Alastair James Kerr SC
- Authors: Glover, Graham B
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70658 , vital:29686 , https://hdl.handle.net/10520/EJC53959
- Description: Professor Alastair James Kerr SC passed away at Settlers Hospital in Grahamstown on the 29th of September 2010. He was eighty-eight years of age. Ironically, his death occurred at the time that the third part of the 2010 SALJ appeared in print, containing a tribute to one of the other great writers on South African contract law, Professor Richard (Dick) Christie, who had passed away earlier in the year (see A J G Lang 'Professor Richard Hunter Christie: A memorial tribute' (2010) 127 SALJ 414). 2010 may have been a momentous year in South Africa for many reasons, but the deaths of these two men in the same year has left the landscape of our contract law irrevocably changed, even though their ideas will live on through their published works.
- Full Text: false
- Date Issued: 2011
In vitro toxicity testing of zinc tetrasulfophthalocyanines in fibroblast and keratinocyte cells for the treatment of melanoma cancer by photodynamic therapy
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
Integrating scholastic and practice-centred epistemologies in a post-graduate professional degree
- Authors: Lotz-Sisitka, Heila , Ellery, Karen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69489 , vital:29542 , https://hdl.handle.net/10520/EJC37710
- Description: This article argues for the integration of both scholastic and practice-centred epistemologies within an Environmental Education (EE) post-graduate curriculum that is oriented towards sustainability and socio-ecological justice. It is an interpretive study based on an in-depth analysis of five assignments by four scholars registered for the M.Ed. EE course at Rhodes University where a contextualised, reflexive research process, based in a work-place context, forms the integrative pedagogic tool. Analyses indicate that involving students in such a process, with close support and guidance, is an effective means of developing both scholastic and practical epistemologies. It is concluded that research-led integration of scholastic and practice-centred epistemologies in a transformational curriculum has the potential to provide epistemological access to the academy, advance knowledge within disciplines, and challenge the dominance of scholastic knowledge in higher education settings.
- Full Text:
- Date Issued: 2011
Investigation of homogeneous photosensitized oxidation activities of palladium and platinum octasubstituted phthalocyanines
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
JM Coetzee's Disgrace: a reader's guide, and: JM Coetzee's austerities
- Authors: Marais, Mike
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144231 , vital:38323 , DOI: 10.2979/reseafrilite.42.4.135
- Description: Like all of the other publications in the series of which it forms a part, Andrew van der Vlies's Disgrace: A Reader's Guide conforms to a set format: a preface, followed by biographical information on the novelist and the context in which he or she wrote the text concerned, and then a longer section comprising a paraphrase and discussion of the work and its reception, together with suggestions for further reading. Despite these structural constraints, van der Vlies provides a very fine introduction to Disgrace in this volume. Readers will find especially insightful his treatment of Coetzee's preoccupation with alterity, and the responsibility, both ethical and aesthetic, that such otherness exacts. One very slight criticism I have of the monograph is that it could have contained more references to discussions of Coetzee's use of narrative point of view in its list of recommended reading. (James Meffan and Kim Worthington's examination of the ambivalent relationship between David Lurie and the narrator's voice comes to mind here, for instance.) Having said this, however, I have little doubt that van der Vlies's guide will prove a useful and comprehensive introduction to Disgrace in university programs.
- Full Text:
- Date Issued: 2011
Knowing, acting and being: Epistemological and ontological access in a Science Extended Studies course
- Authors: Ellery, Karen
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69471 , vital:29540 , https://hdl.handle.net/10520/EJC37737
- Description: Gross participation and throughput rates in higher education institutions in South Africa indicate an inequitable and poorly functioning system. This interpretive study argues for an approach that enhances epistemological and ontological access and examines how an intervention that includes an overt approach in dealing with the nature of science, coupled with student involvement in an independent research project in a Science Extended Studies course, can enhance such access to higher education study. Analysis of project outcomes and student critical reflections indicated access to scientific and academic Discourses was enhanced through: developing improved procedural and conceptual scientific knowledge; meaningful engagement with the language, norms and conventions of the Discourse; integrating everyday knowledge into more abstract scientific knowledge; awareness of the process of validation of scientific knowledge, of the limitations of science, and of the impact of science on society; and transforming personally by developing scientific discursive identity and a sense of belonging. In conclusion, it is argued that curriculum interventions that focus on epistemological and ontological aspects of learning could appropriately be used throughout the higher education science sector.
- Full Text:
- Date Issued: 2011
Learning to squander: making meaningful connections in the infinite text of world culture
- Authors: Jamal, Ashraf
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147391 , vital:38632 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC45816
- Description: In this article on South African visual art I fix my sight on a global interhuman and aesthetic sphere in which region/nation/transnation merge to produce a cultural economy that overlaps and cannot be satisfactorily grasped according to a centre-periphery model. This eschewal of existing binary models also means a reconceptualisation of the liminal as an in-between space in a fixed divide. Currently it is not only the margin that is indeterminate, but the infinite text of the global cultural economy within which visual art plays its part.
- Full Text:
- Date Issued: 2011
Life history and population dynamics of invasive common carp, Cyprinus carpio, within a large turbid African impoundment
- Authors: Winker, A Henning , Weyl, Olaf L F , Booth, Anthony J , Ellender, Bruce R
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124898 , vital:35708 , https://doi.10.1071/MF11054
- Description: Common carp (Cyprinus carpio) is one of the world’s most widely introduced and established freshwater fishes (Casal 2006). The species is considered to be one of the eight most invasive freshwater fishes (Lowe et al. 2000) and worldwide, it accounts for most of the records of successful establishments and adverse ecological effects (Casal 2006; Kulhanek et al. 2011). This invasive success suggests that feral C. carpio is equipped with a set of adaptable life history attributes that allow it to successfully colonise a wide range of habitats (Koehn 2004; Zambrano et al. 2006; Britton et al. 2007). Where feral C. carpio occurs in high densities, it is often perceived as an invasive pest species (Sivakumaran et al. 2003; Brown and Walker 2004; Koehn 2004) because it can have severe impacts on habitat heterogeneity and biodiversity by increasing water turbidity through its bottom feeding behaviour, increasing nutrient availability, decreasing benthic and macrophyte density and diversity, altering zooplankton assemblages and decreasing endemic fish abundance (Zambrano et al. 2001; Khan 2003; Kulhanek et al. 2011). Within south-east Australia, for example, C. carpio comprises the largest proportion of the ichthyobiomass in the continent’s largest river system – the Murray–Darling Basin (Gehrke et al. 1995). As a consequence, serious concerns about its threat to endemic freshwater species (Koehn 2004) have prompted several of the most recent investigations into its life history (e.g. Sivakumaran et al. 2003; Smith and Walker 2004; Brown et al. 2005). Other potential threats posed also include competition with indigenous species and the spread of diseases and parasites (Dudgeon et al. 2006). In South Africa, for example, Asian tapeworm Bothriocephalus acheilognathi is now widely distributed in seven river systems and has infected eight novel cyprinid hosts due to the translocation of infected by C. carpio from a centralized aquaculture facility (Stadtlander et al. 2011).
- Full Text:
- Date Issued: 2011
LTSP DNS round robin clusters: green technology access enablers for telecommunication services in marginalised communities
- Authors: Siebörger, Ingrid , Terzoli, Alfredo , Hodgkinson-Williams, Cheryl
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428437 , vital:72511 , https://d1wqtxts1xzle7.cloudfront.net/75984640/177-libre.pdf?1639074275=andresponse-content-disposi-tion=inline%3B+filename%3DLTSP_DNS_Round_Robin_Clusters_Green_Tech.pdfandExpires=1714912779andSignature=Gmd52OTCvGmiKhiFiQH~rrfp6lSPbp7glndLPn7V4Jy5yt7lU-eToE4IPxr7lDQQOdUW348nkXIMgYHnXkWjWl7nYBM7hlluxJGd15oKbpifvTofHVVEB-kOLbz0caOrAodnS~eMHdebRQOumKSAHPGQkqem756vbw0KV7bhmFQ0TUN-vsVeBoH5ftfg7s355Oh9EZCQhZu~~P0AWzlSRnMTH~6vpj3EKvp7P4gy55oISZ~207VFFFZidb90aoP7JWehRYjRqn3Tk19A6nwm4o9U-wc9Dz1MrCy-YfbqOxdNulQh4bti2WI7DA6C3Q8TMCbtqnZskXQYsIzfEianS~gw__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: Rural development is seen as a priority in South Africa; information and knowledge are key strategic resources for social and economic develop-ment. Information Communication Technologies (ICTs) are seen as im-portant tools in rural development, assisting in enabling change through economic development. In rural areas where ICT infrastructure is being expanded and deployed there is a need to provide appropriate technolo-gies that support sustainability and meet the needs of the local communi-ty. In this paper we argue that the use of Linux Terminal Server Project (LTSP) cluster servers are appropriate technologies for use in computer laboratory environments for relatively inexpensive access to technologies by schools and local communities in rural areas. Typically LTSP clusters are deployed when there is a need to support 100s or 1000s of comput-ers, however, we argue that by reusing recycled (older) desktop or server computers as cluster servers could lower the entry level costs of LTSP computing while maximising the use of available resources. The paper details the configuration of a Domain Name System (DNS) round robin cluster solution together with initial testing and results. It is suggested that LTSP cluster solutions, and the DNS round robin implementation, show promise for use in providing access technologies to rural communities and schools.
- Full Text:
- Date Issued: 2011
Microelectrochemical patterning of gold surfaces using 4-azidobenzenediazonium and scanning electrochemical microscopy
- Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
- Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
- Full Text:
- Date Issued: 2011
National case study : teacher professional development with an education for sustainable development focus in South Africa: development of a network, curriculum framework and resources for teacher education
- Authors: Lotz-Sisitka, Heila
- Date: 2011
- Subjects: Teachers -- Training of , Career development , Sustainable development -- South Africa
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59646 , vital:27634 , https://www.ajol.info/index.php/sajee/article/view/122242
- Description: This national case study reports on the development of a national network, curriculum framework and resources for teacher education, with specific focus on the inclusion of environment and sustainability, also known as education for sustainable development (ESD) in the South African teacher education system. It reviews and reports on the history of environment and sustainability education in teacher education, and from this, the national case study begins to conceptualise a new approach to environment and sustainability teacher education within a new curriculum policy environment, and a new teacher education and development policy environment. Action research case study methodology is used to document the first phase of the emergence of this network, and this report covers Phase 1 of the initiative, which covers formation of the network, review of previous practices, three conceptual development pilot studies undertaken in both in-service and pre-service teacher education environments and a piloting of a ‘Train the Trainers’ or ‘Educate the Teacher Educators’ programme, which complements and extends the actual teacher education and development (TED) programme under development. The study highlights critical insights of relevance to the shift to a content referenced curriculum in South Africa, and shows how the ‘knowledge mix’ which forms the foundation of the new Teacher Education Qualifications Framework can be engaged. It also highlights some features of the changing knowledge environment, and what dominant knowledge practices are in environment and sustainability-related teaching and teacher education practices, opening these up for further scrutiny. It raises concerns that dominant knowledge work, while integrating a range of forms of knowledge (as is expected of the teacher education system under the new policy), tends to be limited by content on problems and issues for raising awareness, and fails to develop deeper conceptual depth and understanding of environment and sustainability, as issues based knowledge dominates. Similarly, it fails to support social innovation as a response to environment and sustainability concerns, as awareness raising dominates in dominant knowledge work. The study provides a revised conceptual framework for the Teacher Development Network (TEDN) programme, with guidance on key elements necessary to take the programme forward in Phase 2.
- Full Text:
- Date Issued: 2011