Evaluation of antifungal effect of Parkia biglobosa and Vitellaria paradoxa against selected pathogenic fungi

The aim of this study was to evaluate the antifungal effects of extracts of two plant species namely Vitellaria paradoxa and Parkia biglobosa against growth of some selected fungal species. Aqueous and ethanolic extracts of these plant species were assessed against Aspergillus flavus, Candida albican and Trichophyton mentagrophyte. Phytochemical analysis of these plants showed the presence of alkaloids, flavonoids, tannins, saponins and other secondary metabolites. The minimum fungicidal concentration (MFC) of aqueous extract of P. biglobosa was 150 mg mL-1 against both C. albican and A. flavus. On the other hand, ethanolic extract of this plant species had MFC of 300 mg mL-1 for A. flavus, while there was no MFC for C. albican. Likewise, aqueous extract of V. paradoxa also had same value of MFC against C. albican as well as A. flavus. Ethanolic extract of V. paradoxa had MFC of 150 and 300 mg mL-1 against C. albican and A. flavus, respectively. The combined aqueous extracts of these plant species showed MFC of 300 mg mL-1 against both the C. albican and A. flavus. By contrast, the mixture of ethanolic extracts had MIC of 150 mg mL-1 against C. albican, and no MFC for A. flavus

Heat Transfer to Sub- and Supercritical Water Flowing Upward in a Vertical Tube at Low Mass Fluxes: Numerical Analysis and Experimental Validation

Heat transfer to supercritical water (SCW) flowing upward in a vertical heated tube at low mass fluxes (<i>G</i> ≤ 20 kg/m² s) has been numerically investigated in COMSOL Multiphysics and validated with experimental data. The turbulence models, essential to describing local turbulence, in COMSOL have been checked under conditions in which empirical heat-transfer correlations are available, and it is concluded that the shear-stress transport (SST) turbulence model gives the most accurate results. The numerical results obtained show a buoyancy induced circulation of the fluid resulting from gravitational force acting on density gradients as well as a thin thermal boundary layer with a steep temperature gradient at the inner wall and a flat temperature profile in the bulk fluid. The heat-transfer coefficient of SCW is enhanced near the pseudocritical temperature (<i>T</i>_pc) and is deteriorated at temperatures above <i>T</i>_pc. A new heat-transfer correlation has been developed and validated with experimental data