http://hdl.handle.net/10204/911 2013-05-23T13:57:03Z http://hdl.handle.net/10204/6725 Title: Phthalocyanines in batteries and supercapacitors Authors: Oni, J; Ozoemena, KI Abstract: Numerous are the ways through which phthalocyanines have been put into very good use. The on-going search for new energy storage and conversion systems has made phthalocyanines even prettier as alternatives to metal and metal oxide catalysts because of their lower cost. This review article looks through a very narrow window of the applications of phthalocyanines in batteries and supercapacitors as a means of improving the qualities such as cycle property, energy density, capacity, open circuit voltage, etc, of these devices. 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), ppp 754- 760 2012-08-01T00:00:00Z http://hdl.handle.net/10204/6721 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 http://hdl.handle.net/10204/6717 Title: Using modified multiple phosphorus sensitivity indices for mitigation and management of phosphorus loads on a catchment level Authors: Oberholster, PJ; Dabrowski, J; Botha, A-M Abstract: The relationships between river and lake phosphorus sensitivity, environmental drivers and catchment characteristics within the upper Olifants River and Lake Loskop were studied over a period of four years to come up with mitigation and management strategies. Using modified indices it was evident that the best strategy for improving the trophic state of Lake Loskop was to drastically reduce the external nutrient loading coming from the upper Olifants River catchment. According to the lake phosphorus sensitivity index (LPSI) developed, Lake Loskop was phosphorus sensitive and will possibly respond to phosphorus reduction in its upper catchment. The river phosphorus sensitivity index (RPSI) developed showed that certain rivers and streams in the upper catchment of Lake Loskop were particularly sensitive to increases in phosphorus (P) loads. The substrate of these rivers and streams consisted of approximately 90 % cobbles or bedrock and showed eutrophic conditions during low flow regimes. The increase in P loads in these streams stimulates the productivity and growth of periphyton dominated by filamentous green algae mats. On the other hand, a restriction of light penetration into the water column by high concentrations of inorganic suspended solids limited the growth of both benthic and planktonic algae in > 3 order streams dominated by sand or mud bottom substrates, thus making these streams less sensitive to high P loads. Rivers and streams in the upper catchment that required mitigation of P loads were identified according to the RPSI and different P load management practices were outlined. The findings of this study are important for restoration and management purposes of increased P loads in conjunction with river characteristics and phytoplankton occurrence. The modified indices developed for P management can be a useful tool in river basins in other parts of the world with the similar environmental drivers and catchment characteristics. Description: Copyright: 2012 Schweizerbart Science Publishers. This is an ABSTRACT ONLY. The definitive version is published in Fundamental and Applied Limnology, vol. 182(1), pp 1-16 2013-01-01T00:00:00Z http://hdl.handle.net/10204/6695 Title: Architecture for user preference-based dynamic service selection in grid infrastructure using mobile devices for SMMEs Authors: Manqele, S; Dlodlo, N; Adigun, M; Xulu, SS Abstract: Grid computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications and some cases, high performance oriented. In this research a user preference is described as a user’s description of the service that the user intends to utilize to solve his/her problem, and service selection is defined as the process of matching the user preference with the available services in the Grid. Description: 14th Annual Conference on World Wide Web Applications, Durban, South Africa, 7-9 November 2012. Published in ZAW3 2012 2012-11-01T00:00:00Z