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The influence of the throughflow and gravity fluctuation on thermosolutal convection in an anisotropic porous bed with the Darcy–Brinkman effect is considered numerically. The critical Rayleigh numbers for the onset of stationary and oscillatory modes have been found via linear instability analysis. The impact of various gravitational functions in the presence of throughflow on stability is studied. The analysis has been carried out for decreasing and increasing gravity fluctuations. The convective problem has been numerically analyzed using a single-term Galerkin approach. The results show that the mechanical anisotropy parameter and Lewis number have a destabilizing effect, while the thermal anisotropy parameter, Darcy number, solutal Rayleigh number, throughflow parameter, and gravity parameter have a stabilizing effect on stationary and oscillatory convection. It is clear that the system changes in a way that makes it more stable for case (iii) gravity fluctuation and more unstable for case (iv) gravity fluctuation.

The effect of a heat source and temperature gradient on Brinkman–Bènard Triple-Diffusive magneto-Marangoni (BBTDMM) convection in a two-layer system is investigated. The two-layer system is horizontally infinite and is surrounded on all sides by adiabatic boundaries. It is exposed to basic uniform and non-uniform temperature profiles and heat sources. The appropriate eigenvalues and thermal Marangoni numbers (TMNs), which depend on temperature and concentration, are obtained for the temperature profiles (TPs) for lower rigid and higher free boundaries with surface tension. The transformed system of ordinary differential equations is solved by using an exact technique. For all three TPs, the impact of significant relevant parameters on these eigenvalues, and hence on BBTDMM convection, are investigated versus the thermal ratio. It is observed that, by increasing the values of the modified internal Rayleigh number for the fluid layer and the solute Marangoni numbers, the Darcy number, and the viscosity ratio for the set of physical parameters chosen in the study, one can postpone BBTDMM convection. Higher values of the modified internal Rayleigh numbers for the porous layer augment BBTDMM convection.

The problem of Bènard-Magneto-Marangoni convection in a composite layer which is infinite along x and y directions is considered for the Darcian case in the presence of constant heat source/sink in both the layers. This composite layer is subjected to uniform and nonuniform temperature gradients. The eigenvalue, thermal Marangoni number is obtained in closed form with the lower surface rigid and upper surface free with surface tension effects for the velocity and isothermal temperature boundary combinations. The influence of porous parameter, magnetic field and nonuniform temperature gradients on the Eigen value problem are discussed. It is experiential that the effect of heat source/sink in the fluid layer is dominant on the eigenvalue over the same in the porous layer. The important parameters like Chandrasekhar number, modified internal Rayleigh number and thermal ratio which control Bènard-Magneto-Marangoni convection are discussed in detail. Publisher's Version

A simple, sensitive and selective high performance liquid chromatography method has been developed and validated for the estimation of benzyl quinolone carboxylic acid (BQCA) in Sprague-Dawley (SD) rat plasma and tissue samples. Plasma and tissue samples were extracted by a protein precipitation technique using methanol as a precipitating agent and donepezil as the internal standard. Chromatographic separation was performed on a Hibar C18 column with a mobile phase of acetonitrile and potassium dihydrogen orthophosphate buffer (20 mM, pH 6.5) at a flow rate of 0.8 mL min−1. The lower limit of quantitation of the developed method was found to be 2.0 ng mL−1 and 5.0 ng g−1 for plasma and tissue samples, respectively. Following intraperitoneal (i.p.) administration, BQCA was remarkably absorbed into the systemic circulation with maximum concentration (∼8000.0 ng mL−1) within 1.5 h. The order of the area under the curve results from the tissue distribution study was kidney > lung > liver > brain > spleen > heart. BQCA was rapidly taken up into the brain resulting in a maximal brain concentration after 1.5 h which was maintained for up to 3–4 h. The method was successfully applied in the analysis of BQCA in plasma and tissue samples following i.p. administration to SD rats at a dose of 10 mg kg−1.