The vascular vessel wall is constantly exposed to biomechanical forces, such as shear and tensile stress. Biomechanical forces are important for several physiological and pathological processes and have been shown to regulate a number of fundamental vascular functions, such as vascular tone and remodeling processes. The aim of the present thesis was to study the effects of biomechanical forces ...

The average bed and sidewall shear stresses in smooth rectangular open-channel flows are determined after solving the continuity and momentum equations. The analysis shows that the shear stresses are function of three components: (1) gravitational; (2) secondary flows; and (3) interfacial shear stress. An analytical solution in terms of series expansion is obtained for the case of constant eddy...

High levels of fluid shear stress at the blood vessel wall directly stimulate von Willebrand factor (vWF)-mediated platelet adhesion and aggregation and thereby contribute to the pathogenesis of arterial thrombosis. We have found that a pathological level of arterial wall shear stress (90 dynes/cm2) induces platelet aggregation that is associated with the phosphorylation of pleckstrin, a M(r) 4...

The glycocalyx layer on the surface of an endothelial cell is an interface barrier for uptake of macromolecules, such as low-density lipoprotein and albumin, in the cell. The shear-dependent uptake of macromolecules thus might govern the function of the glycocalyx layer. We therefore studied the effect of glycocalyx on the shear-dependent uptake of macromolecules into endothelial cells. Bovine ...

Fluid shear stress has profound effects on cell physiology. Here we present a versatile microfluidic method capable of generating variable magnitudes, gradients, and different modes of shear flow, to study sensory and force transduction mechanisms in cells. The chip allows cell culture under spatially resolved shear flow conditions as well as study of cell response to shear flow in real-time. U...

The wall shear stress pattern was measured in a rigid plastic cast of a canine artery during steady flow by means of an electrochemical technique. The topographic distribution of shear stress is very nonuniform, with regions of high and low shear in close proximity. The steady shear stresses are highest at the leading edge of flow dividers and at the entrance regions to branch vessels. The shap...

We carried out pointwise local velocity measurements on 40 mM cetylpyridinium chloride-sodium salicylate (CPyCl-NaSal) wormlike micellar solution using high-frequency ultrasound velocimetry in a Couette shear cell. The studied wormlike solution exhibits Newtonian, shear-thinning and shear-thickening rheological behavior in a stress-controlled environment. Previous rheology, flow visualization a...

The effect of shear stress on the viability of Chaetoceros muelleri was studied using a combination of a rheometer and dedicated shearing devices. Different levels of shear stress were applied by varying the shear rates and the medium viscosities. It was possible to quantify the effect of shear stress over a wide range, whilst preserving laminar flow conditions through the use of a thickening a...

In vitro investigations of the responses of vascular endothelium to fluid shear stress have typically been conducted under conditions where the time-mean shear stress is uniform. In contrast, the in vitro experiments reported here have re-created the large gradients in surface fluid shear stress found near arterial branches in vivo; specifically, we have produced a disturbed-flow region that in...

We have investigated the structural change of an immiscible polymer blend in shear flow when subjected to a step electric field. During the process three-dimensional images were successfully constructed with a confocal scanning laser microscope and at the same time the transient shear stress was also measured. The interface tensor was calculated from the images. Several factors are incorporated...