Determination of thermal properties of some ceiling material commonly used in Ijebu- Ode, Nigeria

The study investigates the thermal properties of different insulating material used in building construction in Ijebu Ode, a tropical rainforest region, south western, Nigeria. Five insulating material; asbestos, Plaster of Paris (P.O.P), PolyVinyl Chloride (PVC), hardboard and paperboard, were subjected to thermal investigation using Lee’s disc electrical method. The result obtained showed that the thermal conductivities obtained are within the range of values specified for good insulating materials. Asbestos was found to be associated with the least thermal conductivity of the value . --while PVC had the highest thermal conductivity values of . --. This may be associated with the temperature and the heat flux on the surface of the material. The results obtained for thermal conductivity, thermal resistivity and thermal diffusivity correlated favourably when compared with those of previous work from other locations. Asbestos being the material with the lowest thermal conductivity is therefore recommended for use as the suitable insulating ceiling material in the study area. Keywords: thermal conductivity, diffusivity, resistivity, Lee’s dis

Heavy metal contamination of Clarias gariepinus from a lake and fish farm in Ibadan, Nigeria

Adult Clarias gariepinus (African Catfish) were purchased from EleiyeleLake and Zartech fish farm in Ibadan. Water samples were also collected in February (dry season) and June (rainy season), 2002. Gill, bone, intestine, muscle and water samples were analyzed for five metals: manganese, copper, zinc, iron, and chromium by atomic absorption spectroscopy (AAS) in two separate experiments. In each case, two tissues were compared with the levels of the metals in water viz: Gill, bone, and water; intestine, muscle and water. Generally, lower concentrations of the metals were recorded in water than fish tissues. Higher concentrations of zinc than recommended by the Federal Environmental Protection Agency were recorded in the fish during the dry season. Iron was the dominant metal in the muscle while Chromium was the least. Significant differences (p<0.05) were recorded in copper and zinc concentrations in the muscle, intestine and water during the dry and rainy seasons .In gill, bones and water, significant differences (p<0.05) were only recorded for the two stations for copper during the rainy season and only zinc was significantly different (p<0.05) in the dry season. It was concluded that though the heavy metals of interest were present in measurable quantities there were still within safe limits for consumption

Numerical investigation on the thermal-nanofluidic flow induced transverse and longitudinal vibrations of single and multi-walled branched nanotubes resting on nonlinear elastic foundations in a magnetic environment

Carbon nanotubes (CNTs) have attracted great attention due to their tremendous mechanical, thermal, structural and electrical properties leading to many promising applications. The unique and interesting properties of CNTs, such as their mechanical and electrical features, have fascinated industries and researchers to implement CNTs for production of different electromechanical devices. However, it is established that the phenomenon of buckling often occurs when CNTs are subjected to compressive loads and their frequencies under vibration are in order of Tera-Hz and Giga-Hz. Moreover, the profound dynamic behaviours of nanotube under the influences of slip when conveying fluid and magnetic field require a serious and meticulous study. Therefore, this study focuses on the vibration analysis of nanofluid-conveying embedded multi-walled branched nanotubes resting on Winkler-Pasternak foundation in a thermal-magnetic environment. Using Euler-Bernoulli theory, Hamilton's principle and nonlocal elasticity theory, fully coupled equations of motion governing the transverse and longitudinal vibrations of the nanotube are developed. Also, the equation of the deformation of the nanotubes as well as the pressure variation in the tubes are developed. Additionally, Navier-Stoke's equation and energy equation for the fluid and nanotube are coupled with the vibration models. The dynamics of the multi-walled carbon nanotubes when coupled with Navier-Stokes and energy equations require meticulous study as it is different from the usual assumption of plug flow. Therefore, in this present work, the developed coupled systems of nonlinear partial differential equations are solved using multi-dimensional numerical PDEs solvers coupled with PDE-tools in MATLAB. With the aids of the solutions, parametric studies were performed. The results indicate that increasing the downstream angle decreases the stability of the system. Also, the results obtained from the dynamic behaviour of the system indicate that the magnetic effect has an attenuating or damping effect of about 20 %. Furthermore, the plug flow assumption deviates from actual working processes by over 11 %. The analytical solutions verified and validated with existing analytical, numerical and experimental results. It is envisaged that the present study will give better insight into nanotubes design and serve as an index for subsequent works in the research area