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Makinde O.D.,Stellenbosch University | Khamis S.,Nelson Mandela African Institute of Science and Technology NM AIST | Tshehla M.S.,Stellenbosch University | Franks O.,Nelson Mandela Metropolitan University
Advances in Mathematical Physics | Year: 2014

Heat transfer characteristics of a Berman flow of water based nanofluids containing copper (Cu) and alumina (Al2O3) as nanoparticles in a porous channel with Navier slip, viscous dissipation, and convective cooling are investigated. It is assumed that the exchange of heat with the ambient surrounding takes place at the channel walls following Newton's law of cooling. The governing partial differential equations and boundary conditions are converted into a set of nonlinear ordinary differential equations using appropriate similarity transformations. These equations are solved analytically by regular perturbation methods with series improvement technique and numerically using an efficient Runge-Kutta Fehlberg integration technique coupled with shooting scheme. The effects of the governing parameters on the dimensionless velocity, temperature, skin friction, pressure drop, and Nusselt numbers are presented graphically and discussed quantitatively. © 2014 O. D. Makinde et al.

Kwon Y.-K.,Korea Research Institute of Bioscience and Biotechnology | Kwon Y.-K.,Korea Basic Science Institute | Jie E.Y.,Korea Research Institute of Bioscience and Biotechnology | Sartie A.,International Institute Of Tropical Agriculture | And 4 more authors.
Food Chemistry | Year: 2015

To determine whether or not FT-IR spectroscopy could be used for taxonomic and metabolic discrimination of African yam lines, tuber samples from African and Asian yam species were subjected to FT-IR. Most remarkable spectral differences between African and Asian yams were found in the 1750-1700 cm -1 region, polysaccharide (1200-900 cm-1) and protein/amide I and II (1700-1500 cm-1) regions of FT-IR spectra. A hierarchical dendrogram based on partial least square-discriminant analysis (PLS-DA) of FT-IR data from 7 African yam species show phylogenetic relationship. In addition, the content of dioscin, a steroidal saponin found in yam tuber, was predicted using a PLS regression model with regression coefficient R2 = 0.7208 indicated that prediction model had average accuracy. Thus, considering these results we suggest that FT-IR combined with multivariate analysis could be applied as a novel tool for metabolic evaluation and high-throughput screening of African yam lines with higher content of dioscin. © 2014 Elsevier Ltd. All rights reserved.

Schafer A.I.,Institute of Functional Interfaces IFG | Schafer A.I.,Nelson Mandela African Institute of Science and Technology NM AIST | Schafer A.I.,University of Edinburgh | Hughes G.,University of Edinburgh | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

Lack of access to safe drinking water remains a present concern in many developing countries, particularly in rural locations. Membrane water treatment technologies have the potential to remove microbiological and chemical contaminants reliably and simultaneously from a wide range of water sources. When powered by renewable energy, these systems are autonomous and have the ability to 'leapfrog' over installation of traditional infrastructure for electricity and water supply to reach remote communities. In this paper, current estimated costs for water, membrane plants and infrastructure are compared to indicate the window of opportunity for these exciting renewable energy powered membrane (RE-membrane) technologies. General estimated costs for decentralized membrane systems are within the range of some untreated water costs in developing countries. Specific system costs, however, are very process and location dependent. The appropriateness of a successful approach thus depends partially on careful examination of these parameters. In view of the comparisons made here, the biggest hurdle to adoption of the RE-membrane technology in a remote location may not be cost, but rather sustainability issues such as the lack of skilled personnel for operation and maintenance, service networks, availability of spare parts, socio-economic integration and adaptive capacity of communities to transfer and develop technology appropriate to local needs and circumstances. © 2014 Elsevier Ltd.

Byanyuma M.,Nelson Mandela African Institute of Science and Technology NM AIST | Kalolo S.,Nelson Mandela African Institute of Science and Technology NM AIST | Mrutu S.I.,Nelson Mandela African Institute of Science and Technology NM AIST | Nyakyi C.,Nelson Mandela African Institute of Science and Technology NM AIST | Sam A.,Nelson Mandela African Institute of Science and Technology NM AIST
2013 Pan African International Conference on Information Science, Computing and Telecommunications, PACT 2013 | Year: 2013

Broadband connectivity is a key strategic resource for assisting change in social and economic development and wealth creation. Tanzania rural areas, where 75% of the population live, are characterized by limited ICT infrastructure that are dominated by low data rate such as GPRS, EDGE and VSAT network services which are also too expensive for the rural population. In this paper we propose last-mile broadband connectivity frameworks based on the existing optical fiber backhaul in an effort to ensure that marginalized communities are connected with high data rates and affordable service costs. Further, we evaluate the frameworks based on network deployment cost, data rates, service coverage and accessibility to test their suitability to Tanzania rural environment. © 2013 IEEE.

Pogrebnoi A.M.,Nelson Mandela African Institute of Science and Technology NM AIST | Pogrebnaya T.P.,Nelson Mandela African Institute of Science and Technology NM AIST | Kudin L.S.,Ivanovo State University of Chemistry and Technology | Tuyizere S.,Kigali Institute of Science and Technology
Molecular Physics | Year: 2013

Geometrical structure, vibration spectra, and enthalpies of dissociation have been investigated for the ions BaCl3 -, Ba 2Cl3 +, Ba3Cl5 +, and Ba4Cl7 + which were detected earlier in the saturated vapour over BaCl2. Quantum chemical methods of density functional theory, the second and the fourth order Møller-Plesset perturbation theory have been applied. The effective core potential with cc-pVTZ basis set for barium atom and two full-electron basis sets including the diffuse and polarised basis functions for chlorine atom were used. The effect of the basis set size and the computation method on the results was analysed. According to the results, all the ions possess the compact shaped structure. The equilibrium geometrical structures were found as follows: the planar D3h for BaCl3 -, triple bridged bipyramidal D3h for Ba2Cl3 +, hexabridged D3h for Ba3Cl5 +, and septuple bridged C2v for Ba4Cl7 +. For positive ions, the different isomeric structures were considered, but no isomers for these ions have been found. The geometrical parameters and vibration frequencies were utilised for computing of thermodynamic functions of the ions, and then the thermodynamic functions were used for the treatment of the experimental mass spectrometric data. The enthalpies of formation ΔfH°(0 K) of the ions were determined (in kJ/mol): -994 ± 6 (BaCl3 -), -481 ± 10 (Ba 2Cl3 +), -1276 ± 14 (Ba 3Cl5 +), -2048 ± 35 (Ba 4Cl7 +). © 2013 Taylor & Francis.

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