in this article six new copoly(amide-imide)s (11a-c) were synthesized through the directpolycondensation reaction of 1,3-bis[4,4'-(trimellitimido) phenoxy] propane (6) with 3,3'-diamino diphenyl sulfone (7), 4,4'-diaminodiphenyl ether (8) and 1,5-naphtalene (9) in thepresence of fumaric acid (10) as a second diacid in a medium consisting of n-methyl-2-pyrrolidone, triphenyl phosp...

There has been extensive theoretical debate over whether population viscosity (limited dispersal) can favour cooperation. While limited dispersal increases the probability of interactions occurring between relatives, which can favour cooperation, it can also lead to an increase in competition between relatives and this can reduce or completely negate selection for cooperation. Despite much theo...

An iterative solution to the inverse problem of elasticity and viscosity is proposed in this paper. A new dynamic finite element model that is consistent with known rheological models has been derived to account for the viscoelastic changes in soft tissue. The model assumes known lumped masses at the nodes, and comprises two vectors of elasticity and viscosity parameters that depend on the mate...

The flow of generalized Newtonian fluids with a rate-dependent viscosity through fibrous media is studied, with a focus on developing relationships for evaluating the effective fluid mobility. Three methods are used here: (i) a numerical solution of the Cauchy momentum equation with the Carreau or power-law constitutive equations for pressure-driven flow in a fiber bed consisting of a periodic ...

The effect of viscosity ratio (λ, defined as viscosity of surrounding medium/viscosity of fluid jet) on stability of axisymmetric (m=0) and asymmetric (m=1) modes of perturbation on a liquid-liquid jet in presence of radial electric field (E0 ), is studied using linear stability analysis. The viscosity ratio is shown to have a damping effect on both the modes of perturbation. However the effect...

According to Stokes' law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measur...

The effects of exponentially varying viscosity and linearly varying thermal conductivity on unsteady MHD natural convective flow past a semi infinite vertical plate in a thermally stratified medium is studied. The variables of both viscosity and thermal conductivity are considered only a function of temperature. The governing boundary layer equations of continuity, momentum and energy have been...

It is well known that the viscosity of a liquid is a measure of its resistance to shear. Upon the introduction of small solid objects into a viscous medium, the internal motion of the liquid when caused to flow is made more complicated than it would be otherwise and the resistance to shear is thereby increased. Einstein (4) has derived the following formula relating the viscosity of a suspensio...

Physiological wall shear rates and stresses in vessel culture or tissue engineering are relevant for maintaining endothelial cell (EC) integrity. To this end, the culture medium should have an appropriate viscosity. The viscosity of a standard culture medium was increased using xanthan gum (XG) and compared with literature data on whole blood, resulting in a medium with blood-analog shear-thinn...

In the present work, a gastroretentive in situ gelling liquid formulation for controlled delivery of ranitidine was formulated using sodium alginate (low, medium and high viscosity grades), calcium carbonate (source of cations) and ranitidine. Prepared formulations were evaluated for viscosity, buoyancy lag time and buoyancy duration, drug content and in vitro drug release. Formulation variable...