Effect of Hall current on transient hydromagnetic Couette–Poiseuille flow of a viscoelastic fluid with heat transfer

The unsteady Couette–Poiseuille flow of an electrically conducting incompressible non-Newtonian viscoelastic fluid between two parallel horizontal non-conducting porous plates is studied with heat transfer considering the Hall effect. A sudden uniform and constant pressure gradient, an external uniform magnetic field that is perpendicular to the plates and uniform suction and injection through the surface of the plates are applied. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are taken into consideration. Numerical solutions for the governing momentum and energy equations are obtained using finite difference approximations. The effect of the Hall term, the parameter describing the non-Newtonian behavior, and the velocity of suction and injection on both the velocity and temperature distributions is examined.     

Potentiometric Response of Modified Carbon Paste Electrode Based on Mixed Ion‐Exchangers

A new chemically modified carbon paste electrode based on a mixture of two ion‐exchangers namely chlorpheniramine‐silicotungstate (CPM‐ST) and chlorpheniramine‐tetraphenylborate (CPM‐TPB) as ion‐exchange site for determination of chlorpheniramine maleate (CPM) was described. The best performance was exhibited by the electrode having the paste containing 3.0 wt% ion‐exchangers (CPM‐ST&CPM‐TPB), 48.5 wt% graphite, 47.5 wt% DOPh and 1.0 wt% NaTPB. The proposed chemically modified carbon paste electrode exhibited a Nernstian response for CPM over a wide concentration range of 1.2×10^?6 to 1.0×10^?2 M with a detection limit of 5.1×10^?7 M between pH 4.5 and 7.7 with fast response ≤10 s. The sensor showed good selectivity for CPM with respect to a large number of inorganic cations, organic cations, sugars, amino acids and some common drug excipients. The modified electrode was applied to potentiometric determination of CPM in its pharmaceutical preparations and biological fluids (serum and urine) with average recoveries of 97.5–102% and relative standard deviations of 0.32–1.97%.