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Biorheology is an international interdisciplinary journal that publishes research on the deformation and flow properties of biological systems or materials. It is the aim of the editors and publishers of
Biorheology to bring together contributions from those working in various fields of biorheological research from all over the world. A diverse editorial board with broad international representation provides guidance and expertise in wide-ranging applications of rheological methods to biological systems and materials.
The aim of biorheological research is to determine and characterize the dynamics of physiological processes at all levels of organization. Manuscripts should report original theoretical and/or experimental research promoting the scientific and technological advances in a broad field that ranges from the rheology of macromolecules and macromolecular arrays to cell, tissue and organ rheology. In all these areas, the interrelationships of rheological properties of the systems or materials investigated and their structural and functional aspects are stressed.
The scope of papers solicited by
Biorheology extends to systems at different levels of organization that have never been studied before, or, if studied previously, have either never been analyzed in terms of their rheological properties or have not been studied from the point of view of the rheological matching between their structural and functional properties. This biorheological approach applies in particular to molecular studies where changes of physical properties and conformation are investigated without reference to how the process actually takes place, how the forces generated are matched to the properties of the structures and environment concerned, proper time scales, or what structures or strength of structures are required.
Biorheology invites papers in which such 'molecular biorheological' aspects, whether in animal or plant systems, are examined and discussed. While we emphasize the biorheology of physiological function in organs and systems, the biorheology of disease is of equal interest. Biorheological analyses of pathological processes and their clinical implications are encouraged, including basic clinical research on hemodynamics and hemorheology.
In keeping with the rapidly developing fields of mechanobiology and regenerative medicine,
Biorheology aims to include studies of the rheological aspects of these fields by focusing on the dynamics of mechanical stress formation and the response of biological materials at the molecular and cellular level resulting from fluid-solid interactions. With increasing focus on new applications of nanotechnology to biological systems, rheological studies of the behavior of biological materials in therapeutic or diagnostic medical devices operating at the micro and nano scales are most welcome.
Abstract: Specimens of bave (undegummed silk thread) were collected from cocoons of various origins of parent silkworm races, such as Japanese, Chinese, European, Korean and tropical origins, and from as many races as possible. An apparatus was set up to measure the dynamic elastic modulus of these specimens. In all the categories of the races tested, the elastic modulus was linearly related to the size of bave, regardless of the portion of cocoon layer from which the specimens were taken. This correlation was concluded to be universal to the silk thread of Bombyx mori L. species; however, values of the regression…coefficient and of the elastic modulus were susceptible to the origin of silkworm races, depending on whether they were native or improved.
Abstract: The effects of the deformation of red blood cells on non-Newtonian viscosity of a concentrated red cell suspension are investigated theoretically. To simplify the problem an elastic spherical shell filled with an incompressible Newtonian fluid is considered as a model of a normal red cell. The equation of the surface of the shell suspended in a steady simple shear flow is calculated on the assumption that the deformation from a spherical shape is very small. The relative viscosity of a concentrated suspension of such particles is obtained based on the “free surface cell” method proposed by Happel. It is shown…that the relative viscosity decreases as the shear rate increases.
Keywords: Red blood cell deformation, Red blood cell suspension, Non-Newtonian viscosity
vol. 20, no. 5, pp. 471-483, 1983
Abstract: The intensity of light scattering by blood in a tube of diameter 0.26 cm was measured with an apparatus devised by us at different angles on an incident cross-sectional plane. Changes in angular distribution of light intensity associated with hemolysis, and changes in hematocrit (Ht), red blood cell (RBC) swell ing, and flow rate were plotted on polar coordinates. The dyssymmetry index, defined as the ratio of the intensity of light at 45° to that at 135°, was used to characterize the shape of the diagrams of light scattering. The index decreased with Ht, flow rate, but increased with RBC swelling.…It is concluded that light scattering by blood requires intactness of the RBC membrane. Even when the cell membrane is intact, light scattering is subject to changes with the flow rate of blood, presumably due to RBC aggregation.
Keywords: Light scattering by blood, Hemolysis, Hematocrit, RBC aggregation, Flow rate of blood, Dyssymmetry index
vol. 20, no. 5, pp. 485-494, 1983
Abstract: Complex Young’s modulus of blend gels of gelatin and kappa-carrageenan or agarose has been measured in order to clarify the protein-polysaccharide interaction in biological systems. The mixture of gelatin and kappa-carrageenan showed phase separation in the intermediate volume fraction of gelatin, and it formed a homogeneous gel when the volume fraction of gelatin is very large or very small. Since the dynamic Young’s modulus for blend gels of kappa-carrageenan and gelatin was larger than the calculated one from a theory for dispersed systems, some structural reinforcing must occur. The mixture of agarose and gelatin showed the inverse tendency. It was…concluded that the role of electrolytic groups was dominant in dilute gels, while molecular entanglement became more important in concentrated gels.
Abstract: Steady flows and pulsatile flows of a Newtonian fluid through a channel with a rectangular hump were numerically studied as a two-dimensional model of blood flow in a constricted artery. From the numerical calculation, it was shown that one of the hydrodynamic causes of endothelial lesion of artery and post-stenotic dilatation can be found in the large temporal variation of shear stress behind a constricted portion of artery. Local maximum of the pressure there can be seen as secondary factor for the post-stenotic dilatation.
Abstract: The complex viscosity η ∗ has been measured of bovine red blood cells suspended in a medium of isotonic NaCl solutions including dextran and buffered with potassium phosphate at pH 7.0. A multiple lumped resonator apparatus was used at the frequencies of 144, 572, 1491, 3742, and 8026 Hz at 20.0°C. Due to the high molecular weight of dextran the medium also exhibited some viscoelasticity η s ∗ . So we adopted the complex specific viscosity η sp ∗ = ( η ∗…− η s ∗ ) / | η s ∗ | . At 20.0°C η sp ∗ decreased with the frequency where the hematocrit was 0.233 and η s 0.34 poise. The measurements were made for the medium with different viscosity at 5.0°C and 25.0°C. The results are compared with the theory of elastic shells.
Keywords: Red cells, Suspensions, Viscoelasticity, Membrane rigidity
vol. 20, no. 5, pp. 519-529, 1983
Abstract: The static and dynamic viscoelastic properties were studied of longitudinal and circumferential strips excised from various large veins of dogs. The mechanical behavior in longitudinal direction could be regarded as elastic, while that in circumferential direction was highly viscoelastic. No distinct regionality was observed in either of the longitudinal and the circumferential groups. Noradrenaline and papaverine did not alter the elastic behavior of the longitudinal strips. In circumferential strips, however, noradrenaline caused a considerable decrease in stress relaxation and some steepening in the slope of the upper limb of hysteresis loop. Papaverine did not affect the circumferential characteristics. These findings…suggest the dominant contribution of smooth muscle tone to the circumferential characteristics of venous walls. Pretreatment with formic acid abolished the occurrence of stress relaxation in circumferential direction but produced no change in the longitudinal behavior. This indicates that elastin fibers may be a principal determinant of the elastic behavior in longitudinal direction and that a residual tension observed in stress-relaxation tests of circumferential strips may be due to stretched elastin fibers. The elastic moduli of elastase pretreated venous walls were in the order of 108 dynes/cm2 , about 1000 times higher than those of the control. Accordingly, collagen fibers seemed not to play any appreciable role in the rheological behavior of venous walls under physiological conditions. This inference was supported by histological observations of venous walls under unstretched and stretched states. Models were proposed in regard to the architecture of the fibrous elements in the venous walls.