Convective diffusion from a non-uniformly distributed source in non-Newtonian fluids: a theoretical investigation and experimental confirmation

This work presents a complete theoretical study of the process of convective diffusion from a non-uniformly distributed source in a non-Newtonian fluid flowing through a straight tube. The influence of the governing parameters on the dispersion process is studied and the results are examined in terms of the interaction of rheology, fluid mechanics and diffusion. Experimental studies have been conducted to obtain the diffusivity values of NaOH in aqueous polymer solutions and provide the first test of the potential of this technique for diffusivity measurement in difficult systems

Convective diffusion from a non-uniformly distributed source in flowing blood

The experimental evaluation of solute diffusivity in blood in or near a zero shear rate region poses difficulties, particularly at low hematocrits. This work studies the pertinent theoretical aspects of a possible flow technique which may circumvent these difficulties. The dispersion in a Casson fluid flowing laminarly in a circular tube is studied under the conditions when a solute is injected continuously but non-uniformly from a centrally placed source. The plots of centreline concentration decay as a function of the axial distance as well as the radial concentration profiles are made and their significance for evaluating the diffusivity is critically discussed

Design and properties of phenoxo-bridged binuclear, trinuclear and tetranuclear macrocyclic complexes

Multinuclear complexes derived from binucleating and tetranucleating macro-cyclic ligands of the types tetraaminodiphenol and octaaminotetraphenol are reported. The effect of electronic interactions between metal centres held in close proximity by the macro-cyclic ligands on chemical reactivities, redox and magnetic properties of the complexes is discussed. Systematic changes in the structure and stereochemistry of the metal complexes brought about by variation of the auxiliary axial ligands are examined. A magneto-structural relation for the binuclear nickel (II) complexes implicating linear dependence of spin-exchange integral (J) on Ni-O(phenoxide)-Ni bridge angle or Ni...Ni separation is discussed