Nonsimilar mixed convection flow of a non-Newtonian fluid past a vertical wedge

The flow and heat transfer characteristics of a second-order fluid over a vertical wedge with buoyancy forces have been analysed. The coupled nonlinear partial differential equations governing the nonsimilar mixed convection flow have been solved numerically using Keller box method. The effects of the buoyancy parameter, viscoelastic parameter, mass transfer parameter, pressure gradient parameter, Prandtl number and viscous dissipation parameter on the skin friction and heat transfer have been examined in detail. Particular cases of the present results match exactly with those available in the literature.

Mixed convection in non-Newtonian fluids along a horizontal plate in a porous medium

The problem of mixed convection from horizontal surfaces in a porous medium saturated with a power-law-type non-Newtonian fluid is investigated. The transformed conservation laws are solved numerically for the case of variable wall hear pur conditions. Results for the details of the velocity and temperature fields as well as the Nusselt number have been presented. The viscosity index ranged from 0.5-1.5.

Non-exponentiality in electron transfer kinetics: Static versus dynamic disorder models

Non-exponential electron transfer kinetics in complex systems are often analyzed in terms of a quenched, static disorder model. In this work we present an alternative analysis in terms of a simple dynamic disorder model where the solvent is characterized by highly non-exponential dynamics. We consider both low and high barrier reactions. For the former, the main result is a simple analytical expression for the survival probability of the reactant. In this case, electron transfer, in the long time, is controlled by the solvent polarization relaxation-in agreement with the analyses of Rips and Jortner and of Nadler and Marcus. The short time dynamics is also non-exponential, but for different reasons. The high barrier reactions, on the other hand, show an interesting dynamic dependence on the electronic coupling element, V-el.

Nonsimilar solutions for mixed convection in non-Newtonian fluids along horizontal surfaces in porous media

A nonsimilar boundary layer analysis is presented for the problem of mixed convection in power-law type non-Newtonian fluids along horizontal surfaces with variable heat flux distribution. The mixed convection regime is divided into two regions, namely, the forced convection dominated regime and the free convection dominated regime. The two solutions are matched. Numerical results are presented for the details of the velocity and temperature fields. A discussion is provided for the effect of viscosity index on the surface heat transfer rate.

Non-viral ex vivo hepatic gene transfer by in situ lipofection of liver and intraperitoneal transplantation of hepatocytes

Perfusion of liver with plasmid DNA-lipofectin complexes via the portal vein results in efficient accumulation of the vector in hepatocytes. Such hepatocytes, when administered intraperitoneally into a hepatectomized rat, repopulate the liver and express the transgene efficiently. This procedure obviates the need for large-scale hepatocyte culture for ex vivo gene transfer. Further, intraperitoneal transplantation is a simple and cost-effective strategy of introducing genetically modified hepatocytes into liver. Thus, in situ lipofection of liver and intraperitoneal transfer of hepatocytes can be developed into a novel method of non-viral ex vivo gene transfer technique that has applications in the treatment of metabolic disorders of liver and hepatic gene therapy.

Temperature dependence of non-Debye disorder in doped manganites

Ca-doped manganite La1-xCaxMnO3 samples with x=0.2 and 0.4 were investigated by extended x-ray absorption fine structure (EXAFS) as a function of temperature and preparation method. The samples exhibit characteristic resistivity change across the metal-insulator (MI) transition temperature whose shape and position depend on Ca-doping concentration and sample thermal treatment. EXAFS results evidenced an increase of nonthermal disorder at the MI transition temperature which is significantly correlated with the resistivity behavior.

Mode shapes during asynchronous motion and non-proportionality indices

When synchronous motion does not exist, it is not possible to draw the classical mode shapes. In this paper, a representative shape of motion during free vibration of a non-classically damped system is sought. It is noted that this shape provides an optimal representation of free motion. Interpretations of the optimality thus introduced are presented. Their connection with non-proportionality of damping and of gyroscopy is brought out. In the spirit of the optimality presented in this paper, two indices of non-proportionality are defined. Properties of these indices are discussed. Comparison with other indices of non-proportionality available in the literature is presented. Illustrative examples are given. (C) 1999 Academic Press.

Non-interferometric methods of phase estimation for application in optical tomography

We describe here two non-interferometric methods for the estimation of the phase of transmitted wavefronts through refracting objects. The phase of the wavefronts obtained is used to reconstruct either the refractive index distribution of the objects or their contours. Refraction corrected reconstructions are obtained by the application of an iterative loop incorporating digital ray tracing for forward propagation and a modified filtered back projection (FBP) for reconstruction. The FBP is modified to take into account non-straight path propagation of light through the object. When the iteration stagnates, the difference between the projection data and an estimate of it obtained by ray tracing through the final reconstruction is reconstructed using a diffraction tomography algorithm. The reconstruction so obtained, viewed as a correction term, is added to the estimate of the object from the loop to obtain an improved final refractive index reconstruction.

Nonsimilar solutions for free convection in non-Newtonian fluids along a vertical plate in a porous medium

A nonsimilar boundary layer analysis is presented for the problem of free convection in power-law type non-Newtonian fluids along a permeable vertical plate with variable wall temperature or heat flux distribution. Numerical results are presented for the details of the velocity and temperature fields. A discussion is provided for the effect of viscosity index on the surface heat transfer rate.

Stability of non-parabolic flow in a flexible tube

Flows with velocity profiles very different from the parabolic velocity profile can occur in the entrance region of a tube as well as in tubes with converging/diverging cross-sections. In this paper, asymptotic and numerical studies are undertaken to analyse the temporal stability of such 'non-parabolic' flows in a flexible tube in the limit of high Reynolds numbers. Two specific cases are considered: (i) developing flow in a flexible tube; (ii) flow in a slightly converging flexible tube. Though the mean velocity profile contains both axial and radial components, the flow is assumed to be locally parallel in the stability analysis. The fluid is Newtonian and incompressible, while the flexible wall is modelled as a viscoelastic solid. A high Reynolds number asymptotic analysis shows that the non-parabolic velocity profiles can become unstable in the inviscid limit. This inviscid instability is qualitatively different from that observed in previous studies on the stability of parabolic flow in a flexible tube, and from the instability of developing flow in a rigid tube. The results of the asymptotic analysis are extended numerically to the moderate Reynolds number regime. The numerical results reveal that the developing flow could be unstable at much lower Reynolds numbers than the parabolic flow, and hence this instability can be important in destabilizing the fluid flow through flexible tubes at moderate and high Reynolds number. For flow in a slightly converging tube, even small deviations from the parabolic profile are found to be sufficient for the present instability mechanism to be operative. The dominant non-parallel effects are incorporated using an asymptotic analysis, and this indicates that non-parallel effects do not significantly affect the neutral stability curves. The viscosity of the wall medium is found to have a stabilizing effect on this instability.