Biorheology - Volume 5, issue 2

Authors: Murata, Tadayoshi | Oka, Syoten

Article Type: Research Article

Abstract: It is shown how to determine parameters of a material obeying Casson’s equation by some rheometers. Casson has proposed an equation for the flow of varnishes relating the shear stress F to the rate of shear D . This relation has the form, ( F ) = k 0 + k 1 ( D ) , k 0 and k 1 being constants. This equation is generally called Casson’s equation. We have determined the …parameters k 0 and k 1 , that is, the viscosity η c corresponding to k 1 2 and the yield value τ f corresponding to k 0 , by a rotating coaxial cylinder viscometer and a cone and plate viscometer. The determination of the parameters can be made by the following procedure. First, we substitute the flow curve for Casson’s equation into the general relationship between the torque M and the angular velocity Ω for a non-Newtonian fluid. From a plot of Ω vs. M we can get an asymptote. Then we can determine η c from the slope of the asymptote and τ f from the intersection of the asymptote with the abscissa. Show more

DOI: 10.3233/BIR-1968-5201

Citation: Biorheology, vol. 5, no. 2, pp. 95-102, 1968

Authors: Cerny, L.C. | Grauz, J.D. | James, H.

Article Type: Research Article

Abstract: The osmotic pressures of mixtures containing albumin, various dextrans and one hydroxyethyl starch sample were determined. The interaction coefficient was calculated in order to access the effectiveness of these plasma expanders as osmotic colloidal agents. A series of commercially prepared hydroxyethyl starch solutions was used in a viscometric evaluation of cell-protein interactions with resuspended red cells at low shear rates.

DOI: 10.3233/BIR-1968-5202

Citation: Biorheology, vol. 5, no. 2, pp. 103-110, 1968

Authors: Kline, K.A. | Allen, S.J. | DeSilva, C.N.

Article Type: Research Article

Abstract: A continuum model of fluid suspensions is applied to the Poiseuille flow of a fluid in which suspension deformations are negligible. A substructure spin boundary condition intermediate between zero spin and zero antisymmetric stress is formulated by introducing a wall condition parameter. A simple relation is postulated between the wall condition parameter and the suspension concentration and an expression is obtained for the relative viscosity of the fluid suspension. The resulting expression is found to agree closely with the experimental results of Vand [J. Phys. Colloid Chem. 52 , 300, 1948].

DOI: 10.3233/BIR-1968-5203

Citation: Biorheology, vol. 5, no. 2, pp. 111-118, 1968

Authors: Ferguson, J. | Boyle, J.A. | McSween, R.N.M. | Jasani, M.K.

Article Type: Research Article

Abstract: Using a Weissenberg rheogoniometer the steady shear flow properties of a series of synovial fluids from patients suffering from various forms of arthritis were examined. Clear differences in flow behavior were detected. In certain cases peak stresses were encountered in both the tangential and normal directions at the onset of shearing. Joint stiffness in anyone patient and hyaluronic acid/protein complex concentration were found to correlate with viscosity. Rheumatoid factors and antinuclear factors did not. Synovial fluid flow behavior showed no sign of circadian changes.

DOI: 10.3233/BIR-1968-5204

Citation: Biorheology, vol. 5, no. 2, pp. 119-131, 1968

Authors: Charm, S. | Paltiel, B. | Kurland, G.S.

Article Type: Research Article

DOI: 10.3233/BIR-1968-5205

Citation: Biorheology, vol. 5, no. 2, pp. 133-145, 1968

Authors: Benis, A.M. | Lacoste, J.

Article Type: Research Article

Abstract: The problem of regional blood flow distribution in small vessels is considered by means of a passive model of a portion of the vascular bed. The following complexities are considered: (1) non-Newtonian behavior of blood including effects of red cell aggregation, (2) the complexity of the vascular geometry including taper, curvature and effects at bifurcations, and (3) flow unsteadiness. Three rheological models are considered, namely Newtonian, power-law and Casson fluids. It is shown that changes in flow distribution and even reversal of flow direction can occur if the fluid is non-Newtonian but not a power-law fluid. It is shown that …this condition is satisfied for blood in the low flow-rate regime where erythrocyte aggregation is important. Computations indicate that local pressure changes due to inertial effects as a result of vessel non-uniformity are not important. It is suggested that alterations in blood flow distribution due to rheological changes will show up experimentally in measurements of ventilation-perfusion relationships in the lung or in analysis of in vivo dye-dilution curves. Show more

DOI: 10.3233/BIR-1968-5206

Citation: Biorheology, vol. 5, no. 2, pp. 147-161, 1968

Authors: Scott Blair, G.W. | Burnett, J.

Article Type: Research Article

Abstract: Hartert’s thrombelastograph is used to help in the diagnosis of abnormal conditions of blood clotting. Its practical usefulness lies in its capacity to distinguish borderline cases. It is felt that its efficiency for this purpose would be enhanced if the equations for the rate of increase of the complex modulus during coagulation and of its decrease during subsequent softening (fibrinolysis and/or retraction) were known. The parameters of these equations could then be used for diagnostic and prognostic purposes and the equations should also throw some light on the mechanism of fibrin polymerization and of softening. Experiments have been done …on bovine blood (also using a somewhat similar but larger torsiometer) and on human blood as well as on fibrinogen-thrombin. The polymerization process, especially in the case of fibrinogen-thrombin, appears to consist of two well-defined stages, an equation proposed in a previous paper holding in the earlier stage and a still simpler equation in the later stage; but the very last stage of coagulation does not follow any known equation. The effects of additions of substances known to induce or inhibit fibrinolysis and retraction in human blood were confirmed; but considerable differences were found, in some cases, in the behavior of bovine blood. Some marked effects on rate and extent of coagulation produced by these substances do not appear to have been previously recorded. Show more

DOI: 10.3233/BIR-1968-5207

Citation: Biorheology, vol. 5, no. 2, pp. 163-176, 1968

Authors: Scott Blair, G.W. | Burnett, J.

Article Type: Letter

DOI: 10.3233/BIR-1968-5208

Citation: Biorheology, vol. 5, no. 2, pp. 177-177, 1968

Article Type: Other

DOI: 10.3233/BIR-1968-5209

Citation: Biorheology, vol. 5, no. 2, pp. 179-179, 1968

Article Type: Correction

DOI: 10.3233/BIR-1968-5210

Citation: Biorheology, vol. 5, no. 2, pp. 181-181, 1968

Authors: Stalker, A.L.

Article Type: Abstract

DOI: 10.3233/BIR-1968-5211

Citation: Biorheology, vol. 5, no. 2, pp. 183-188, 1968