Biorheology - Volume 23, issue s1

Authors: Radtke, H. | Roggenkamp, H.G. | Wolf, S. | Mrowietz, Ch. | Kiesewetter, H.

Article Type: Research Article

Abstract: A new experimental method is described which permits estimation of flow ability of blood: measuring the yield shear stress with the erythrocyte-stasis-meter (ESM). This method is based on the phenomenon that pathological blood under low pressure behaves like a solid body. Knowing the pressure difference at the transition point from solid to fluid behavior and the geometry of the channel, the yield shear stress can be calculated.

DOI: 10.3233/BIR-1984-23S111

Citation: Biorheology, vol. 23, no. s1, pp. 75-77, 1984

Authors: Ravey, J.C. | Ikemoto, S. | Stoltz, J.F.

Article Type: Research Article

Abstract: Blood suspensions have been studied by using an air-bearing viscosimeter which is driven by a rotating magnetic induction. Each transient motion (rise, relaxation with zero or intermittent field) can be considered as a quasi-static motion, from which the curve viscosity-shear gradient can be obtained. Combining several transient motions allows an easier determination of the parameters describing a non newtonian fluid like blood.

Keywords: Viscosimeter, blood rheology, transient flow

DOI: 10.3233/BIR-1984-23S112

Citation: Biorheology, vol. 23, no. s1, pp. 79-82, 1984

Authors: Brancher, J.P. | Lucius, M. | Bernardin, D. | Raihani, R. | Stoltz, J.F.

Article Type: Research Article

Abstract: The viscometer described in this paper comprises a vertical cylinder containing the fluid to be tested and an inner, hollow cylinder floating in the fluid and filled with magnetic liquid. The magnetic liquid and inner cylinder are set in motion by applying a rotating magnetic field. Torque is balanced by the stresses in the fluid and the inertia of the rotating cylinder. The main characteristics of this new apparatus are: - possibility of applying various torques to the rotor. Measurements of angular velocity are made on the inner cylinder (in general, conventional viscometers are built on the opposite principle), …- study in transient flow. Various measurements on Newtonian fluids (water, plasma, oils, etc.) and on blood suspensions have made it possible to improve the accuracy of the method. Show more

Keywords: Viscometer, Magnetic liquid, blood

DOI: 10.3233/BIR-1984-23S113

Citation: Biorheology, vol. 23, no. s1, pp. 83-88, 1984

Authors: Doffin, J. | Perrault, R. | Garnaud, G.

Article Type: Research Article

Abstract: A falling ball viscometer is used to measure whole blood and plasma viscosities. The principle of the device is to determine the fall time of a ball contained in a disposable syringe; the periodic run of the sphere prevents blood sedimentation during the measuring cycle but does not prevent the aggregation process which takes place with a short relaxation time. The analysis of the flow field is discussed relative to previous papers. The study of the dynamics of the falling ball provides two characteristic rates of deformation for the mixed extensional and shear flow field. The Reynolds numbers are calculated …using different velocities and radii. Results on blood and plasma viscosity of patients suffering from rheumatoid arthritis are given in relation with clinical and biological indexes. Show more

Keywords: viscosity, viscometer, blood, rheumatoid, arthritis

DOI: 10.3233/BIR-1984-23S114

Citation: Biorheology, vol. 23, no. s1, pp. 89-93, 1984

Authors: Adjizian, J.C. | Droulle, C. | Osterman, G. | Pignon, B. | Potron, G.

Article Type: Research Article

Abstract: We have studied some rheological parameters in different clinical status by using two coaxial viscometers. The Contraves Low Shear sinus 30 allows available shear rates range from γ ˙ (128s-1 to 0.0175 s-1), and the parameters studied were viscoelastiticy, thixotropy and blood viscosity. The Ecktacytometer1 1 Technicon is another method for measuring cell deformation in couette flow. The aim of our study was to compare these two technics, to consider their clinical interest and finally to visualize an eventual correlation. Technicon

Keywords: blood viscosity, blood thixotropy, blood viscoelasticity, erythrocyte deformability, diffractometry

DOI: 10.3233/BIR-1984-23S115

Citation: Biorheology, vol. 23, no. s1, pp. 95-97, 1984

Authors: Matrai, A. | Flute, P.T. | Dormandy, J.A.

Article Type: Research Article

Abstract: Aggregation and sedimentation of the red cells in the viscometer makes it difficult to obtain good reproducibility at low shear rates. A simple method is described to obtain repeatable torque-time curves with the Contraves LS30. Before starting rotation, the blood sample is agitated by an up and down movement of the bob. This results in identical (within 1-2% of the actual amplitude) repeated tracings even at the lowest shear rates, even with extremely time-dependent samples. The subsequent torque-time curve of the disaggregated and unsettled samples provides an experimental basis for the quantitave description of blood viscoelasticity and for dynamic analysis …of red cell aggregation: furthermore it results in more accurate measurements when comparing different samples and testing therapeutic effects. The method is applicable to any coaxial cylinder type viscometer with manual lowering of the bob. Show more

Keywords: Low shear viscometry, aggregation, sedimentation, time dependence

DOI: 10.3233/BIR-1984-23S116

Citation: Biorheology, vol. 23, no. s1, pp. 99-101, 1984

Authors: Matrai, A. | Warburton, B. | Dormandy, J.A.

Article Type: Research Article

Abstract: The weak interactions between plasma proteins are of possible importance both in haemorheology and in the pathology of several diseases. The use of surface rheology is a convenient way to study the forces arising between surface adsorbed protein molecules. A surface rheological measuring head has been designed for the Contraves LS-30 viscometer. Plasma samples of healthy human subjects showed a rapidly developing viscous surface layer with a mean peak value of 2.10−3 Ns/m surface viscosity at 30–60 seconds. After that the viscosity of the surface layer gradually decreased to zero between 8–20 minutes. The rate of the observed decrease …was not related to shearing. There was no difference between samples anticoagulated with heparin or EDTA. The time course of the described phenomenon coincides with that of thrombocyte and white cell adherence to solid surfaces exposed to plasma. Show more

Keywords: surface rheology, plasma-air interface

DOI: 10.3233/BIR-1984-23S117

Citation: Biorheology, vol. 23, no. s1, pp. 103-105, 1984

Authors: Maurice, G. | Lucius, M. | Stoltz, J.F.

Article Type: Research Article

Abstract: The determination of a constitutive law of a fluid, the red blood can be obtained by fitting the parameters of a theorical law with experimental results. For an experience, several expressions can be agreed, each of them explain a particular property. The aim of my purpose is to describe some mathematical ans numerical methods, in relation with two experiences, able to give the value of an unknown quantity by computation and to fit it with measured quantity. The first method use finite element to modelize a couette nonlinear flow. It can be approach by a very simple model using only …the computation of a nonlinear differential equation. The second use the perturbation method and the expansion in power serie. Show more

Keywords: Blood, Viscosimeter

DOI: 10.3233/BIR-1984-23S118

Citation: Biorheology, vol. 23, no. s1, pp. 107-110, 1984

Authors: Whittington, R.B. | Harkness, J.

Article Type: Research Article

Abstract: This work was done as the first part of a continuing study of neonatal blood. In a recent paper (1), two parameters, “A” (relative whole-blood viscosity at unit rate of shear and 1% haematocrit) and “β ” (shear-sensitivity exponent) were proposed, as characteristics of a given blood-sample. Here, some 60 placentae yielded (after plasma-manipulation) 130 sub-samples having haematocrits ranging from 3% to 90%. Their viscosities were measured in a capillary viscometer set for a constant wall shear-stress of 1855 mPa. “A” and “β ” were calculated by the method given in (1). Multiple calculations on a number of …sub - samples revealed systematic variations within anyone blood; but when every A/β ratio is plotted against the corresponding A, the results follow a smooth curve. This curve occupies a striking, almost central location when A-and-β values from adult normal and pathological bloods (rotational viscometry) are superimposed on the diagram. An analytic form for the close correlation between haematocrit and relative placental blood-viscosity is given by the adoption of a single “group A” and “group β ” for all 130 results. Show more

Keywords: Placental-blood viscosity, haematocrit, shear

DOI: 10.3233/BIR-1984-23S119

Citation: Biorheology, vol. 23, no. s1, pp. 111-114, 1984

Authors: Jung, F. | Roggenkamp, H.G. | Körber, N. | Schneider, R. | Kiesewetter, H.

Article Type: Research Article

Abstract: A new capillary viscometer was developed to eliminate the measuring errors due to insufficient cleaning or the residue of cleaning solution in the capillary. A disposable polyurethane tube which can be discarded after each determination is used as a measuring chamber. This device has been constructed for bed-side application (light weight, dry, thermostat-controlled measuring capillaries, short measuring period, automated process, and easy operation). The Pearson correlation coefficient for comparative measurements with the Coulter-Harkness viscometer was r = 0.979 .

DOI: 10.3233/BIR-1984-23S120

Citation: Biorheology, vol. 23, no. s1, pp. 115-117, 1984