Unsteady natural convection Couette flow of heat generating/absorbing fluid between vertical parallel plates filled with porous material

The extended Brinkman Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertical channel （formed by two infinite vertical and parallel plates） filled with the fluid-saturated porous medium. The flow is triggered by the asymmetric heating and the accelerated motion of one of the bounding plates. The governing equations are simplified by the reasonable dimensionless parameters and solved analytically by the Laplace transform techniques to obtain the closed form solutions of the velocity and temperature profiles. Then, the skin friction and the rate of heat transfer are consequently derived. It is noticed that, at different sections within the vertical channel, the fluid flow and the temperature profiles increase with time, which are both higher near the moving plate. In particular, increasing the gap between the plates increases the velocity and the temperature of the fluid, however, reduces the skin friction and the rate of heat transfer.

Bio-chemical characterization of bacterial flora associated with spoilt vegetables in kaduna markets Northern Nigeria

Some vegetables such as Capsicum annum (Pepper), Lycopersicon esculentum (Tomato), Allium cepa (Onion), Cucumis sativus (Cucumber), Solanum tubero- sum (Potato) and Daucus carrota (Carrot) which are consumed more frequently in the area were obtained from Kaduna central market and Kawo market with the aim of isolating and characterizing the different bacterial flora associated with their spoilage. Four bacteriological media: Mannitol Salt Agar (MSA), MacConkey Agar (MA), Salmonella Shigella Agar (SSA) and Blood Agar (BA) were used for the isolation of the bacterial populations. The results obtained from Kaduna central market indicated the presence of two Gram positive bacteria viz: Staphylococcus and Streptococcus strains as well as three Gram negative bacteria including Escherichia coli, Citrobacter and Klebsiella spp. Staphylococcus aureus is the most abundant (with 80% relative occurrence) with Strep-tococcus spp being the least abundant (with 10% relative occurrence). Furthermore, among the Gram negative isolates, Escherichia coli, Citrobacter and Kleb- siella spp had the highest occurrence of 30% each, while Enterobacter spp had the least. Similar results were obtained of the isolates from Kawo market except that among the Gram negatives, Edwardsiella spp was found in Kawo market but E. coli is absent. More so, S. aureus and K. spp has the highest percentage of 605 each in Kawo market. The result showed that the people consuming these vegetables are at higher risk of boils, carbuncles, impetigo, infections of wounds and burns, breast abscesses, whitlow, osteomyelitis, bronchopneumonia, septicemia, bacteremia, acute endocarditis, food poisoning and scalded skin syndrome due to these bacterial populations.