http://hdl.handle.net/10204/1212 2013-05-21T23:47:39Z 2013-05-21T23:47:39Z Masa, J Ozoemena, K Schuhmann, W Zagal, JH http://hdl.handle.net/10204/6721 2013-05-03T21:55:15Z 2012-08-01T00:00:00Z

Title: Oxygen reduction reaction using N4-metallomacrocyclic catalysts: fundamentals on rational catalyst design Authors: Masa, J; Ozoemena, K; Schuhmann, W; Zagal, JH Abstract: In this review, we describe and discuss the developments in the use of metalloporphyrins and metallophthalocyanines as catalysts for oxygen reduction in aqueous electrolytes. The main goal of most researchers in this field has been to design catalysts which can achieve facile reduction of oxygen by the four-electron transfer pathway at the lowest overpotential possible. With this in mind, the primary objective of this review was to bring to light the research frontiers uncovering important milestones towards the synthesis and design of promising N4-metallomacrocyclic catalysts which accomplish the four-electron reduction of oxygen, and, based on literature, to draw attention to the fundamental requirements for synthesis of improved catalysts operating at low overpotentials. Our emphasis was not to make parallel comparisons between individual classes of N4-metallomacrocyclic complexes with respect to their activity, but rather to focus on the commonalities of the fundamental properties that govern their reactivities and how these may be aptly manipulated to develop better catalysts. Therefore, besides discussion of the progress attained with regard to synthesis and design of catalysts with high selectivity towards four-electron reduction of O2, a major part of the review highlights quantitative structure-activity relationships (QSAR) which govern the activity and stability of these complexes, which when well understood, refined and carefully implemented should constitute a fundamental gateway for rational design of better catalysts. Description: Copyright: 2012 World Scientific Publishing. This is an ABSTRACT ONLY. The definitive version is published in Journal of Porphyrins and Phthalocyanines, vol. 16(7/8), pp 761-784

2012-08-01T00:00:00Z Tsague, HD Nelwamondo, F Msimang, N http://hdl.handle.net/10204/6696 2013-04-18T21:55:18Z 2012-11-01T00:00:00Z

Title: An advanced mutual-authentication algorithm using 3DES for smart card systems Authors: Tsague, HD; Nelwamondo, F; Msimang, N Abstract: One of the most commonly used two-factor user authentication mechanisms nowadays is based on smart card and personal identity number or password. A scheme of this type is usually known as, a smart card based password authentication. The core feature of such a scheme is to enforce two-factor authentication in the sense that, the client must have the smart card and know the card PIN number in order to gain access to the server. In this paper, we propose and advanced remote mutual authentication scheme between a smart card, a smart card reader and the backend server database to ensure system security integrity. Our scheme provides high security and mutual authentication at a reasonable computational cost. Furthermore, it restricts most of the current attack mechanisms. It is simple and can be adapted to any kind of lightweight devices. Description: 2nd International Conference on Cloud and Green Computing (CGC 2012), Xiangtan, Hunan, China, 1-3 November 2012. To be published in IEEE Xpolre.

2012-11-01T00:00:00Z Twinomurinzi, H Phahlamohlaka, J Byrne, E http://hdl.handle.net/10204/6623 2013-03-25T21:55:58Z 2012-04-01T00:00:00Z

Title: The small group subtlety of using ICT for participatory governance: A South African experience Authors: Twinomurinzi, H; Phahlamohlaka, J; Byrne, E Abstract: The greater number of government efforts to stimulate participative governance in communities using Information and Communication Technology (ICT) often fall short of expectations. In South Africa extending egovernment to communities has been in the form of more and/or better equipped ICT-enabled community centres, called Thusong Service Centres. In this paper, based on action research experiences, we report outcomes of interpretive research into ICT-enabled approaches to participative governance in communities. Using the Diffusion of Innovations theory as an analytic lens, the findings reveal a subtlety that is not often mentioned in the call for participative e-governance; people from communities prefer to work in groups rather than individually. The collectiveness inclination is a common denominator of many developing countries where people choose to come together to leverage the few available resources. Individuals become apprehensive when made to work on their own using the ICT. The research reveals the necessity to re-design ICT to suit small groups as part of participative e-governance rather than the normative ICT design that suits individual work styles. Additionally, the research reveals that by working in groups, communities are more willing to accept the government initiatives that are being energised with the use of ICT. Methodologically, the research revealed the ethical issue that arises from action research in its raising of unrealistic expectations in a community. Description: Copyright: 2012 Elsevier. This is the Post print version of the work. The definitive version is published in Government Information Quarterly, vol. 29(2), pp 203-211

2012-04-01T00:00:00Z Mulopo, J Zvimba, JN Swanepoel, H Bologo, LT Maree, J http://hdl.handle.net/10204/6414 2013-01-08T21:55:23Z 2012-01-01T00:00:00Z

Title: Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage Authors: Mulopo, J; Zvimba, JN; Swanepoel, H; Bologo, LT; Maree, J Abstract: Batch regeneration of barium carbonate (BaCO3) from barium sulphide (BaS) slurries by passing CO2 gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO3 recovery in the Alkali Barium Calcium (ABC) desalination process and its use for sulphate removal from high sulphate Acid Mine Drainage (AMD). The effect of key process parameters, such as BaS slurry concentration and CO2 flow rate on the carbonation, as well as the extent of sulphate removal from AMD using the recovered BaCO3 were investigated. It was observed that the carbonation reaction rate for BaCO3 regeneration in a bubbling column reactor significantly increased with increase in carbon dioxide (CO2) flow rate whereas the BaS slurry content within the range 5–10% slurry content did not significantly affect the carbonation rate. The CO2 flow rate also had an impact on the BaCO3 morphology. The BaCO3 recovered from the pilot-scale bubbling column reactor demonstrated effective sulphate removal ability during AMD treatment compared with commercial BaCO3. Description: Copyright: 2012 IWA Publishing. This is an ABSTRACT ONLY. The definitive version is published in Journal of Water Science and Technology, vol 65(2), pp 324-331

2012-01-01T00:00:00Z