We propose a dual-parameter detection method to realize the simultaneous optical absorption and viscoelasticity imaging based on photoacoustic lock-in measurement. Both optical absorption and viscoelasticity properties can be obtained simultaneously by analyzing the amplitude and phase of photoacoustic signals. This method is experimentally verified by imaging of gelatin phantoms with different...

INTRODUCTION Articular cartilage is known to exhibit strong transient mechanical behavior. When subjected to high strainrate loading, its apparent stiffness can be 10 times greater than its stiffness at equilibrium. However, the mechanism of this strain-rate dependent response is not completely understood. While some studies have shown evidence of a fluid-flow dominant mechanism of the strain-r...

BACKGROUND Prior microrheologic assessments of selected, microlitre plugs of cystic fibrosis (CF) sputum suggest no intrinsic rheologic abnormality. However, such analyses may not be representative of CF sputum as a whole. We therefore reassessed this question using whole sputum macrorheology. Additionally, we wished to further explore the relationships between sputum rheology, inflammation and...

Injection of optimized chemistry water in enhanced oil recovery (EOR) has gained much interest in the past few years. Crude oil-water interfaces can have a viscoelastic character affected by the adsorption of amphiphilic molecules. The brine concentration as well as surfactants may strongly affect the fluid-fluid interfacial viscoelasticity. In this work we investigate interfacial viscoelastici...

We present a computational study of the effects of viscoelasticity on the electromechanical behavior of dielectric elastomers. A dynamic, finite deformation finite element formulation for dielectric elastomers is developed that incorporates the effects of viscoelasticity using the nonlinear viscoelasticity theory previously proposed by Reese and Govindjee. The finite element model features a th...

BACKGROUND Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. METHODS Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was s...

The positive relationship between hippocampal structure, aerobic fitness, and memory performance is often observed among children and older adults; but evidence of this relationship among young adults, for whom the hippocampus is neither developing nor atrophying, is less consistent. Studies have typically relied on hippocampal volumetry (a gross proxy of tissue composition) to assess individua...