Influence of Soret and Dufour on mixed convection flow across a vertical cone

This contribution examines the influence of Soret and Dufour on an incompressible viscous fluid flow across a vertical cone. The flow model is framed in the form of mathematical governing equations and a nondimensionalization is performed on them for ease of the numerical computations' examination; the obtained nonsimilarity equations are solved numerically through the bivariate Chebyshev spectral collocation quasi-linearization method. Outcomes of the flow characteristics, velocity, temperature, concentration, skin friction rate, heat, and mass transfer rates are analyzed with the variations of governing parameters, Prandtl number, buoyancy parameter, Schmidt number, buoyancy ratio, Soret and Dufour parameters at various stream-wise spots of the flow. To certify the exactness of the listed computations, we performed a comparison with prior published computations, which were found with great agreement, and the residual analysis study was also portrayed to reflect the convergence and stability of the adopted numerical technique.     

The Experiences of Immigrants in South Africa: a Case Study of Ethiopians in Durban,South Africa

In recent years there has been an increase in the number of immigrants in South Africa from non-SADC countries. This research was conducted with Ethiopian immigrants in Durban in an attempt to shed some insights into this new nexus. The aim of the study was to understand the experiences of Ethiopian immigrants. The decision to migrate is motivated by a number of socio-economic factors including social networks and greater accessibility and availability of opportunities. The findings of this research suggest that most Ethiopian immigrants in South Africa are involved in the informal economic sector. The target of their economic activities is mainly South Africans in the townships and Ethiopian immigrants themselves. Crime is not the major concern because it does not impact the immigrant community. This research found that Ethiopian immigrants have not integrated into the local community. Language is a major barrier to integration. However, more efforts are needed to ensure their integration into the local community.     

Visualisation and quantification of fumonisins bound by lactic acid bacteria isolates from traditional African maize-based fermented cereals,ogi and mahewu

Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB₁ and FB₂) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB₁ most effectively while P. pentosaceus D39 bound the least level of FB₁. The highest levels of FB₂ were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB₁ and FB₂, respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.     

On the Fringe of the Economy: Migrant Street Traders in Durban

The number of migrants working on the streets of cities throughout South Africa has increased tremendously over the past few years. This study draws on qualitative data to understand the experiences of migrant street traders in Durban, South Africa. The qualitative data for the study come from in-depth interviews with local and migrant street traders. Migrant street traders are attracted to Durban because of the economic opportunities that the city offers as well as the lower crime rate than other cities. The findings suggest that migrant street traders make an economic contribution towards the development of the city. Migrants create employment by hiring locals to assist them in their businesses. Some tension exists between local and migrant street traders because of fear of competition. Crime is a concern because it impacts negatively on their businesses. Other challenges experienced by the migrant traders include the harsh treatment by the police and lack of support for informal traders by the municipality. More emphasis should be placed on providing a supportive environment for street trading in Durban.     

Soret and Dufour Effects on Non‐Darcy Free Convection in a Power‐Law Fluid in the Presence of a Magnetic Field and Stratification

In this article, effects of Soret and Dufour on free convection heat and mass transfer along a vertical plate embedded in a doubly stratified power‐law fluid‐ saturated non‐Darcy porous medium in the presence of a magnetic field is considered. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations, with the location along the plate as a parameter and then solved numerically. A parametric study of the physical parameters involved in the problem is conducted and a representative set of numerical results is illustrated by insisting on the comparison between pseudo‐plastic, dilatant, and Newtonian fluids. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(7): 592–606, 2014; Published online 11 November 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21098     

Medium chain and behenic acid incorporated structured lipids from sal,mango and kokum fats by lipase acidolysis

Medium chain (MC) and behenic fatty acids were incorporated into kokum, sal and mango fats using 1,3-specific lipase catalysed acidolysis. The incorporation of fatty acids increased with increase in concentration of fatty acids and duration of reaction. The order of incorporation of fatty acids was C22:0 > C10:0 > C8:0, to the extent of 53%, 42.5%, 35.8%, respectively, after 16 h, using kokum as substrate. The same trend was observed with sal or mango fats as substrates though the percentages incorporated were different. The modified products with higher contents of MC were liquids with no solid fats, even at 0 °C, and which showed low cloud point due to an increase in triacylglycerols containing lower chain fatty acids. The modified products after incorporating both MC and C22:0 showed long melting ranges and were suitable for use in bakery, confectionery, etc. as vanaspati substitutes.