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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: The velocity field external to a stationary ellipsoidal particle with continuously rotating surface motion driven by a surrounding shear flow is calculated. The configuration is intended to model the so-called “tank-treading” behavior of mammalian erythrocytes (red cells) when suspended in shear flow. The boundary-value problem posed is based on the model developed by Keller & Skalak (7) and is solved by adapting Jeffrey’s general solution (9) for the Stokes flow about a rigid, freely rotating ellipsoid immersed in an unbounded viscous flow. Streamlines and velocity profiles in the plane of symmetry are obtained by numerical computations. The flow pattern reveals…two free stagnation points near the ends of the particle and the streamlines branching from these points delineate a region of closed streamlines surrounding the particle and two recirculating wakes extending to infinity both upstream and downstream of the particle. The presence of the wakes suggests a mechanism for enhanced diffusion of smaller solute particles in the surrounding fluid.
Keywords: red cell, tank-treading, velocity field
vol. 20, no. 3, pp. 267-282, 1983
Abstract: Experimental and theoretical results are presented concerning the motion of close-packed red blood cell suspensions subjected to steady simple shear flow. The behavior of the suspension was observed microscopically using a cone-and-plate rheoscope. At moderate and high shear rates the cells show a fairly orderly arrangement, each appearing polygonal in the field of view. An idealized theoretical model for the suspension is developed, in which each cell is a 14-sided polyhedron of varying shape, but with constant surface area and volume. Tank-treading motion of the membrane is predicted, and an approximation to the motion is calculated which is consistent with…the known mechanical properties of the membrane. It is shown that considerably more energy is dissipated in the membrane than in the cytoplasm during tank-treading.
Keywords: rheology, red blood cells, shear flow, tank-treading
vol. 20, no. 3, pp. 283-294, 1983
Abstract: A theoretical analysis is made of the dynamical behavior and bulk rheology of close-packed red blood cell suspensions subjected to simple shear flow. The model far the polyhedral cell shapes and tank-treading membrane motion developed in the companion paper (1) is used. The flow in the thin lubricating plasma layers between cells is analyzed taking into account the mechanical properties of the membrane at the corner regions of sharp membrane curvature. This leads to predictions for the apparent viscosity as a function of hematocrit and shear rate. Good agreement with experimental results is obtained at moderate and high shear rates…(above 20 s−1 ). At lower shear rates, a rapid rise in apparent viscosity has been found experimentally, and the mechanisms leading to this behavior are examined.
Keywords: rheology, red blood cells, blood viscosity, tank-treading
vol. 20, no. 3, pp. 295-309, 1983
Abstract: A number of different experimental techniques have been devised in recent years to use microsieving as a test of the filterability of suspensions of red blood cells. Various indices have been proposed to express the results of these tests. In the present paper a correlation is made of the intrinsic increase in resistance at the level of a single pore in the filter to the macroscopically observed pressure and flow through the entire filter. Further it is shown how a number of different tests may be used to derive the same index. The results apply only to situations in which…there is no plugging of pores.
Keywords: filterability, red cells, microsieving, steady flow theory, pore plugging
vol. 20, no. 3, pp. 311-316, 1983
Abstract: Experiments were performed to study the rheological response of human blood at hematocrit ratios of 0 to 0.45 in axial oscillatory flow in a tube of uniform bore. Three principal regimes of flow were identified, depending on the amplitude of oscillation. At the highest amplitudes (and therefore the largest range of shear rates in the blood) there was turbulent motion and the friction coefficient increased in proportion to the square of the hematocrit. At small amplitudes the friction decreased with increase in amplitude, the rate of decrease increasing with hematocrit. At intermediate amplitudes the friction increased in proportion to the…square of the hematocrit. Glutaraldehyde fixation of the red cells caused increase in the friction, and reduced the rate of decrease of friction with amplitude at small amplitudes. With a stenosis of very modest degree and span the friction in normal blood increased disproportionately, and a small blind hole in the lumen of the stenosis caused additional and disproportionate increase in friction.
Abstract: Flow instability (formation of vortices and a concurrent increase in the apparent viscosity) was studied in the rotational rhombospheroid viscometer of 3°, 5° and 10° gaps over a range of speeds from 10 to 300 r.p.m.. Comparisons between different blood systems were carried out mainly at 250 r.p.m. Experiments were carried out on blood samples obtained directly from human subjects, or from the Blood Bank, or from horses. Reconstituted suspensions of red cells in albumin or dextran were also used. Apparent flow instability was found to be not solely a function of blood viscosity, but a multiple function of many viscosity factors…or blood subphases, including instability-decreasing factors such as haematocrit and aggregation of red cells; and instability-increasing factors such as rigidity of red cells; and thus specific to and characteristic of individual blood samples. Apparent instability can be described by multiple regressions as a function, Z, of red cell rigidity, Tk, blood viscosity, η app , and aggregation of red cells, AG; for example: Z = − 28.29 + 26.24 Tk + 0.109 η app (r = 0.816; P < 0.001), or Z = 5.90 − 0.0165 AG − 0.752 η app (r = 0.573; P < 0.05). The apparent instability can be seen only in one-third of blood samples obtained from horses, and in more than half of blood samples obtained from human donors; majority of human donors shows apparent instability below 3 per cent.