Radon concentration assessment in bank cellars in three Nigerian cities

Cellar workplaces are considered as confined environment with challenging indoor air quality having higher than normal pollutants particularly that of soil gas origin. Radon, a major soil gas, infiltrates and accumulates within indoor spaces and becomes harmful in the absence of ventilation. Radon level in bank basements (cellars) in Ilorin, Lagos and Akure have been sampled and analysed in this study. In Nigeria, most workers in basements are unaware of radon, and there is limited documented research on its health hazards. The survey parameters of radon concentrations were floor types, geographical locations and the influence of atmospheric conditions. Corentium monitor, a continuous, digital radon monitor, temperature meters and Prologue wireless weather station were used for the experiments. Annual average indoor radon concentration for the survey period was 23 Bq/m3. The calculated mean annual effective doses in basements and different floors were below the recommended ICTR level of 3 mSv/y.Keywords: Indoor air quality, Pollutants, Radon, Ventilatio

Comparative biocidal activities of some crude plant species powders against the cowpea weevil (Callosobrochus maculatus (F.)(Coleoptera: bruchidae))

Callosobruchus maculatus is one of the most important pests of cowpea in storage causing severe economic damage to the grain. This study investigated the efficacies of three plant materials (Azadirachta indica, Calotropis procera and Chromolaena odorata) leaves against the cowpea weevil. Concentrations of 0.1, 0.25 and 0.5g of the plant powders were used on 10g of grains with 10 adult weevils in each and a Control (untreated) in triplicates. The results showed significant (P< 0.05) negatively effects of the plant materials on the survival of C. maculatus at the highest concentration. In all trails, mean daily mortality in adult C. maculatus were significantly(p<0.05) increased. All plant powder type were effective but concentration-dependent, with C. procera recording significantly (P < 0.05) higher mortality at the various concentrations while C. odorata, elicited the least mean daily mortality. The lowest LD50 (0.63g) was obtained with C. procera. These plants materials were found to also affect the egg-laying capacity of C. maculatus. Treatment with C. odorata recorded significantly(P<0.05) higher number of eggs laid at all concentrations, though the egg-laying capacity was also concentration-dependent; whereas C. procera recorded the least number of eggs laid. All the three plants powders tested demonstrated significant insecticidal potency on stored cowpea weevils, with C. procera and C. odorata showing significantly higher and lower insecticidal potentials respectively. These findings will help in solving problem associated with food security especially with respect to stored produce

Molecular characterization of spatially heterogeneous populations of the malaria vector (Anopheles gambiae s.l) in Niger State, Nigeria

In this study, Anopheles mosquitoes were characterized through an investigation of adult female mosquitoes for sibling species. For the first time, researchers combined efforts on morphology and DNA barcoding utilizing the markers cytochrome c oxidase subunit I (COI) gene and internal transcribed spacer 2 (ITS2) region was made. Cytochrome c oxidase subunit I and ITS2 regions of morphologically differentiated, Anopheline mosquitoes were sequenced. According to the results of molecular identification (PCR) of the distinctive sibling species of the Anopheline mosquitoes, two sibling species from An. gambiae complex and An. rufipes group were identified viz; An. gambiae ss (Giles 1902) and An. rufipes (Gough 1910), these sibling species were discovered in Bosso LGA's Large water and Gutter. An. gambiae s.s was collected in all the breeding habitats sampled in Katcha, Lapai and Shiroro LGAs. In this report, the habitat breeding density of the An. gambiae s.s. was found to be higher compared to An. rufipes, which was restricted to large water and gutter breeding habitats. This study highlights the usefulness and feasibility of COI and ITS2 genetic markers in recognizing Anophelines, their sibling species, the importance of a unified, systematic approach in mosquito taxonomy and highlights the epidemiological role of An. gambiae s.s. For the first time in Niger State An. rufipes has appeared as a malaria vector, emphasising the need for proper monitoring of this species across the country to effectively set up vector management strategies.&nbsp

Numerical simulation of forced convective heat transfer in inclined elliptic ducts with multiple internal longitudinal fins

The paper presents numerical study of forced convective heat transfer in internally finned elliptic geometry to determine the effect of parameters such as Reynolds number, Prandtl number, aspect ratio, fin heights, number of fins and orientations of the duct on the heat transfer coefficient, temperature history and velocity profiles. The walls were assumed to be subjected to a thermal boundary condition of constant heat flux and the effect of slip boundary is assumed negligible. Finite difference technique was adopted for the solution and results were generated using a code written in Qb-64. The study indicated that number of fins (F=8) provided the optimum heat transfer augmentation. For all the geometries investigated, Nusselt number, average velocity and bulk fluid temperature were enhanced by the inclinations in the range 0°⩽θ⩽75°. For a flow regime of 50⩽Re⩽200, the effect of inclination on heat transfer is negligible, but it worth noting the existence of a critical Reynolds number, Re=200, above which the effect of inclination on fluid flow becomes noticeable. Also, at Pr⩾5, Nusselt number and bulk fluid temperature were independent of fluid properties. The results obtained could be applied in the prediction of parameters for the design of compact heat exchangers for industrial applications. Keywords: Elliptic geometry, Multiple internal fins, Fluid flow, Heat transfer, Temperature history, Velocity profil

Diversities of Anopheles gambiae ss and Plasmodium falciparum in Minna, Nigeria

Genetic diversities of Anopheles gambiae ss and Plasmodium falciparum is a major challenge in malaria control as it affects the vector, treatment and production of a vaccine. The aim of the study is to identify the genetic variabilities of A. gambiae ss using the A. gambiae species-specific multiplex Polymerase Chain Reaction (PCR) and P. falciparum using merozoite surface protein (msp2) as antigenic marker. Results revealed that the A. gambiaes ss identified were of the M-forms and the two families of msp-2, FC27 and 3D7 were observed among the isolates of P. falciparum. Eleven (11) number of genotypes were recorded with FC27 having the highest frequency of 8(26.67%) while 3D7 had the least number of genotypes encountered with 3(10%). The allelic frequency of FC27 type was higher 29(96.67%) than 3D7 alleles with 26 (86.67%). There is no significant difference found in the distribution of FC27 alleles and 3D7 alleles in the study populations (p>0.05). The observed population genetics of A. gambiae ss and P. falciparum is likely to be a consequence of the high transmission intensity. This has important implications for malaria control strategies and vaccine production.Keywords: Genetic veriabilities; malaria control strategy