title: Ultrasound scattering from concentrated suspensions of aggregated red cells in shear flow.
abstract: Ultrasound scattering technique is used to investigate dynamics of reversible fractal aggregates in dense suspensions and analyze shear break-up processes of Rayleigh fractal clusters. On the basis of an homogenous fractal flocculation and the hybrid scattering model in the Rayleigh scattering regime, a first order expression of the ultrasound scattering cross-sectional area per unit of volume (backscattering coefficient) is derived for a dense distribution of correlated Rayleigh fractal clusters. From the scaling laws for shear break-up of reversible aggregates in concentrated suspensions, a rheo-acoustical study is then proposed to describe the shear stress dependence of the low frequency scattered power per unit of volume. In a second part, experimental flow dependent changes of the ultrasound backscattering coefficient in a plane-plane flow geometry were reported to analyze shear break-up processes of hardened or deformable red cell aggregates in polymer solution (neutral dextran polymer). Rheo-acoustical experiments were examined within the framework of the effective mean field approximation and the proposed rheo-acoustical model. The ability of ultrasound scattering to determine the critical disaggregation shear stress inducing a complete disaggregation and to give quantitative information on particle surface adhesive energy are finally analyzed.
authors.affiliation: Groupe de Recherche en Physique et Biophysique (GRPB), 45 rue des Sts-Pères, 75270 Paris Cedex 06, France.
authors.forename: L
authors.initials: L
authors.lastname: Haider
authors.forename: P
authors.initials: P
authors.lastname: Snabre
authors.forename: M
authors.initials: M
authors.lastname: Boynard
mesh_terms: D004903:Erythrocyte Aggregation / Q000502:physiology*; D004912:Erythrocytes / Q000000981:diagnostic imaging*; D017709:Fractals; D018056:Hemorheology; D006801:Humans; D008954:Models, Biological; D013314:Stress, Mechanical; D014463:Ultrasonography