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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 fractionation of micron-size particles according to physical properties of size, density and surface characteristics by centrifugation and electrophoresis is hindered when the particles behave collectively rather than individually. The formation and sedimentation of droplets containing particles is an extreme example of collective behavior and a major problem for these separation methods when large quantities of particles need to be fractionated. In this paper, experiments that measured droplet sizes and settling rates for a variety of particles and droplets are described. Expressions are developed relating the particle concentration in a drop to measurable quantities of the fluids and particles. The…number of particles in each droplet was then estimated along with the effective droplet density and certain trends are noted. Since a major application of this work is the purification of biological cells in the range of 10 microns, for which monodisperse inert particles are not available, red blood cells from different animals fixed in glutaraldehyde provided model particle groups with the necessary size range, visibility and stability for these fluid dynamical studies.
Abstract: A novel technique to prepare isolated transparent natural blood vessels was developed and used to study the detailed flow patterns in some regions of the circulation. It was found that paired spiral secondary flows and recirculation zones form downstream of venous valves, at the arterial T-junctions in the dog abdominal aorta, and in the human carotid sinus over a wide range of geometrical and flow conditions, including the time-averaged mean values of the physiological flow rates.
Abstract: Mass transfer of a solute of small molecular weight across a hydrophilic membrane is discussed and a simplification of the mass transfer analysis is proposed. It was assumed that the permeability of the boundary layer at the membrane surface depends only on the velocity gradient at that membrane surface. Theoretical results are compared with the values of oxygen output at the dialysis membrane activated with an inorganic catalyst, in the presence of hydrogen peroxide, inside a test chamber of a simple geometry and in the flat plate dialyzer. Test chamber data and the theoretical analysis allow for the prediction of…the mass transfer efficiency of the dialyzer.
Keywords: mass transfer, membrane permeability
vol. 20, no. 2, pp. 129-140, 1983
Abstract: The viscosity: shear rate relationship of whole blood is shown to be described to a good approximation by a bi-linear plot on log: log axes. This has allowed an analytical solution to be obtained which gives a full description of the flow properties of blood in rigid tubes of a size where the Fahraeus-Lindqvist effect is minimal As a result the profound effects that changing haematocrit has on blood flow in such tubes can be quantitated. The analysis also Shows that in similar circumstances altering fibrinogen concentration is of rheological significance only at flow rates below the normal physiological range.
Abstract: The problem of peristaltic transport of a fluid of variable viscosity in a non-uniform tube and channel has been investigated under zero Reynolds number, and long wavelength approximation. It is found that, the pressure rise decreases as the fluid viscosity decreases at zero flow rate, is independent of viscosity variation at a certain value of flow rate, and increases if flow rate exceeds further. The difference between two corresponding values (for constant and variable viscosity) of pressure rise, under a given set of conditions increases with increasing amplitude ratio at zero flow rate. Further, for a given zero pressure rise,…the flow rate increases as viscosity of fluid decreases. The pressure rise, in the case of non-uniform geometry is found to be much smaller than the corresponding value in the case of uniform geometry. In Part II (a companion paper), results for uniform tube and channel are obtained and comparison with other theories are made in detail. Finally, the models developed in Part I and Part II are applied and compared with observed flow rates in vas deferens of rhesus monkeys, the small intestine, and the ductus efferentes of the male reproductive tract in the other companion paper, Part III.
Abstract: Using the model of peristaltic flow in non-uniform geometry, developed in the companion paper (Part I), results for uniform tube and channel are obtained in closed form. Comparison of analysis with other theories and the effect of viscosity variation are discussed in detail. Finally, quantitative comparison are made between theory and experiments of Weinberg et al. and Latham.
Abstract: The models of peristaltic flow in non-uniform and uniform tube and channel, developed in the companion papers, Part I and Part II, are applied and compared with the observed flow rates in vas deferens of rhesus monkeys, the small intestine, and the ductus efferentes of the male reproductive tract.
Abstract: A rheological constitutive relation in shear for an apple cortex tissue has been developed based upon creep experiments on solid cylindrical samples of the soft tissue obtained from a specified location of the apple and subjected to constant torques of various magnitudes and duration using a specially developed multiaxial loading device. Results indicate that the material displays non-linear viscoelastic properties which can be characterized by a multiple integral relation between the torque and the unit angle of twist. Using this relation the creep response of the material under two step and three step torque histories and the history with torque…linearly varying with time was predicted and found to agree well with experimental results. Finally, the paper describes a method for obtaining the constitutive relation in shear from the developed unit angle of twist-torque equation. The shear constitutive relation for the tissue has been found to be of the integral type with two kernal functions specifying the rheological response.
Abstract: A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5μ Nuclepore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of…RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about ± 10%. The filtration index is shown to be an intrinsic RBC filterability property.
Abstract: In mucociliary clearance mucus has been found to be essential as coupler between ciliary beat and transport. The rheological properties of mucus are carefully matched to this task. It has to be an incipient gel and deviations from this state, to a sol or to a stiff gel, both render it defective in function. The known rheological properties of normal mucus are shown to be consistent with our understanding of how a periodically interacting set of cilia produce mucus layer flow. A dual requirement has to be met: Adequate tip penetration and adequate force transfer laterally. As a result any…biorheologically properly matched system can replace mucus. Mucociliary clearance is a clear cut, rather well understood case of a general principle of biorheological matching.
Abstract: Samples of respiratory mucus were obtained from the trachea of dogs and patients undergoing bronchoscopy. The samples were studied by laser correlation spectroscopy. The autocorrelation function of laser light scattered by both human and canine respiratory mucus was a single exponential in thick mucus or a double exponential in thin watery mucus. This finding suggests that, as in the case of uterine cervical mucus, the molecular structure of respiratory mucus is an ensemble of entangled, randomly-coiled glycoproteins forming a loose network of variable density rather than a covalently cross-linked molecular network as proposed in earlier studies.
Abstract: We studies the frequency dependence of viscoelastic behavior of human sputum using our newly developed Raised Cosine Pulse (RCP) method. This method needs only 1.5 ml sputum, and allows us to estimate the responses of storage modulus (G ′ ) and loss modulus (G ″ ) to the change of angular frequency ω = 10 − 3 − 10 0 rad.sec−1 in only 2–3 minutes by applying one small pulse strain. Measurements were made at 37°C and within 2 hours…of expulsion. The results obtained by the RCP method and by a conventional method were compared and were roughly in agreement. From the behavior of G ′ and G ″ , the presence of a relaxation region at ω = 3 × 10 − 2 − 3 × 10 − 1 rad.sec−1 could be deduced. The magnitude of relaxation increased and relaxation frequencies decreased, as the purulence of sputum increased. We also observed differences in viscoelastic behavior of sputum resulting from the application of mucolytic agents in vivo, which suggest corresponding changes of mechanical structures to the different pharmacological actions of these drugs.
Abstract: Spinability of normal mucus and of sputum collected in chronic bronchitic patients was measured using an automatic device derived from that developed by Chretien et al (1977) for cervical mucus. Spinability of sputum decreased as the purulence increased. Although significant correlations were found between spinability and apparent viscosity (r = − 0.50 , p < 0.05 ) or elasticity (r = 0.54 , P < 0.02 ), large variations in spinability were observed for sputum samples ranging in a zone of low viscosity and elasticity. Sputum with high spinability exhibited normal transport…rate on the depleted frog palate although their viscosity and elasticity were abnormally low. The significant correlation obtained between spinability and sputum transport rate (r = 0.61 , p < 0.01 ) suggests that this rheological factor, along with viscosity and elasticity, plays an important role in the mucociliary transport mechanism.
Keywords: Respiratory mucus, spinability, viscoelasticity, mucociliary transport
vol. 20, no. 2, pp. 239-249, 1983
Abstract: Nasal mucociliary clearance was measured in both healthy subjects and patients with chronic sinusitis using saccharin granule technique. Nasal mucociliary transit time (ST) was significantly slower in the patients with chronic sinusitis compared with that in controls (p < 0.005 ). Nasal mucus collected from each nasal cavity was used for in vitro bullfrog palate clearance studies and compared to the in vivo nasal ST. Mucociliary clearance rate (MTR) on frog palate was 12.5 ± 2.5 mm/min in the mucus from control subjects, 6.1 ± 1.5 mm/min in the mucus from the patients. The difference was statistically significant…(p < 0.005 ). The MTR on frog palate in the patients whose nasal ST was within normal range was significantly slower than that in controls (p < 0.005 ), but not significantly different from that in the patients whose nasal ST was over the normal range. These results suggest that the nasal mucous properties which decreased the mucociliary clearance on frog palate did not contribute to the mucociliary clearance of the patients who had a normal one. No significant correlation existed between MTR on frog palate and nasal ST in both control and chronic sinusitis. In chronic sinusitis patients, decelerated nasal ST was recovered significantly by normal saline nebulization compared with the value before the nebulization (p < 0.01 ). None of the significant change of ST was observed in control before and after the nebulization.