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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: In the presence of macromolecules, e.g., dextrans, polylysines, heparin, or various plasma proteins, red blood cells (RBCs) aggregate to form rouleaux. Aggregation of RBCs results in an acceleration of erythrocyte sedimentation rate and an elevation of low-shear blood viscosity. The mechanism of RBC aggregation has been postulated to be due to macromolecular bridging between adjacent cell surfaces. The bridging energy is a function of the nature of binding and the number of binding sites between the macromolecules and the cell surfaces. RBC surface is negatively charged due to the presence of sialic acids. The interaction of surface potentials results in…a mutual repulsion between cells, especially in the presence of macromolecules. The magnitude of the repulsion is a function of the surface charge density and the ionic composition of the fluid medium. RBC aggregation occurs when the bridging force due to surface adsorption of macromolecules overcomes the electrostatic repulsive force and mechanical shearing force. The net aggregating energy is stored as a change in membrane strain energy. Studies on the ultrastructure of RBC aggregates have shown that the intercellular distance is a function of macromolecular dimensions and that the shape of RBC aggregates is determined by the net aggregating energy. understanding the force balance in RBC interactions serves to establish the physicochemical principles of cell-to-cell interactions induced by macromolecules. It also provides basic information for the understanding of micromechanics of RBC aggregation in blood rheology.
vol. 16, no. 3, pp. 137-148, 1979
Abstract: The rheological properties of blood, nonNewtonian viscosity in steady flow, frequency dependence and shear rate dependence of viscoelasticity in oscillatory flow, and thixotropy, are brought together by a unifying concept. Rheological states are defined which separate nonequilibrium properties, such as thixotropy, from equilibrium properties, such as steady flow viscosity and sustained oscillatory flow viscoelasticity. It is considered that the aggregation of erythrocytes is the primary process governing the conditions of equilibrium. A generalized Maxwell model is developed to provide a basis for quantitative analysis of equilibrium properties. A shear rate dependent degradation function serves to adjust the model elements to…the flow conditions. Characteristic relaxation times become significant rheological parameters for equilibrium viscosity and viscoelasticity while other characteristic times are important to thixotropy. Numerical data are evaluated for the several rheological properties by comparison with the theory using a computerized regression analysis. These determinations show that nonNewtonian viscosity and viscoelasticity can be calculated using the same numerical properties. Thus, the theory provides a rational framework into which several rheological tests of blood can be placed.
vol. 16, no. 3, pp. 149-162, 1979
Abstract: Velocity profile in the arteriole (diameter 80 to 90 µm) of anesthetized frog web was studied by means of a laser Doppler microscope. Since the laser Doppler microscope yields a particle biased mean of flow velocity, a method was postulated to estimate approximately the virtual velocity. The flow velocity at the central, median and marginal portions as well as the pressure gradient along the stream axis varied in response to the cardiac cycle and with a certain time lag. The virtual velocity profile differed from the one predicted from a Newtonian fluid.
vol. 16, no. 3, pp. 163-170, 1979
Abstract: Vascular diseases and risk factors such as smoking are accompanied by an increase in blood viscosity due to the enhancement of aggregation of the red blood cells. This is demonstrated both for smokers and for patients with peripheral vascular disease by comparing the viscoelasticity of the blood with that from healthy donors. Also, the hematocrit values measured by centrifugation for the smokers and patients were found to be significantly higher than for the healthy donors, this difference being attributed to the effects of aggregation. A new unit, the calculated hematocrit, is recommended. This unit, calculated from measured values of blood…and plasma densities, is independent of the conditions of aggregation.
vol. 16, no. 3, pp. 171-178, 1979
Abstract: The viscoelastic parameters of synovial fluids (SF) from various joint diseases and pure hyaluronic acid (HA) solutions of various concentrations were investigated. The complex coefficient of viscosity for these fluids confirmed to show non newtonian flow effects and to be also a function of the HA content. HA solutions at higher concentrations and SF with meniscus defects and degenerative joint disease show higher elastic components than the viscous. This effect is reversed in the case of traumatic and rheumatic arthritis. The latter display a decrease in both viscous and elastic components. The elastic component proved to be a more sensitive…indicator of the changes in joint effusions.
vol. 16, no. 3, pp. 179-184, 1979
Abstract: The complex rheological behavior of the sy.in under biaxial deformations is exhibited in terms of its experimental stress-strain relationships under constant strain level. The stress-strain relationships are anisotropic, nonlinear, strain rate dependent and have considerable hysteresis. The stress-relaxation modes are strain dependent and different for different components of the stress. The sY.in is therefore nonlinear viscoelastic. An attempt is made to develop a rheological model for the skin which is based on the observed structure of its constituents and their mechanical properties. The model emphasizes the importance of the nonuniformities in the skin’s structure as the possible sources of…the skin’s nonlinear and anistropic behavior. It is shown that these nonuniformities can indeed account for the skin rheological behavior. The model consists of two material parameters and four material functions which can be determined for each specimen from results of specific experiments.
vol. 16, no. 3, pp. 191-202, 1979
Abstract: The experimental findings hitherto reported on the permeability of serum albumin have been interpreted theoretically. Serum albumin may be transported either by vesicles through the protoplasm of endothelial cells or through intercellular junctions. Based on a new molecular picture of protoplasm and the junction, it is concluded that there exist weak bonds between protein molecules in the system and that a part of the bonds is broken down by mechanical disturbances. This facilitates the transport of serum albumin across the endothelium. Thus it is expected that the permeability is enhanced by wall shear stress, oscillatory flow, stretch and vibration. It…is further expected that positive circumferential tension of a blood vessel wall enhances its permeability. This prediction is in good agreement with the experimental finding that hypertensive arterial lesion is apt to develop in those regions where positive circumferential tension is easily induced.
vol. 16, no. 3, pp. 203-209, 1979