Biorheology - Volume 23, issue 1

Article Type: Editorial

DOI: 10.3233/BIR-1986-23107

Citation: Biorheology, vol. 23, no. 1, pp. I-III, 1986

Authors: Akeson, Stephen P. | Mel, Howard C.

Article Type: Research Article

Abstract: The red blood cell apparent-size spectrum, obtained using resistive pulse spectroscopy (RPS) with typical electrical response times, is characterized by a bimodality, which in turn is quantified by a bimodality index. The magnitude of the index reflects the non-uniformity in distribution of particle trajectories within the orifice, itself a function of cell deformability. In measurements of mixed populations of glutaraldehyde-fixed and native cells, the index is found to be linearly dependent on the fraction of deformable cells. The index, previously known to be a function of flow rate, is now found to be a function of the electric field …strength within the orifice as well. Furthermore a previously reported time-dependent loss of bimodality, for the uncounted cells remaining in a counting-vial suspension, appears to be a function of the electric field strength far outside the orifice. The relationship between the pressure drop across the orifice and the average linear fluid velocity through the orifice has been measured, and it is concluded that the flow within the orifice is non-turbulent, at all but the highest flow rates. The non-turbulent flow condition, coupled with the short resident time within the orifice, implies that the observed selection of different trajectories (as a function of cell deformability) must take place well in front of the orifice. Show more

Keywords: Computers, Cytological techniques, Erythrocyte indexes, Erythrocytes, Flow cytometry, Rheology

DOI: 10.3233/BIR-1986-23101

Citation: Biorheology, vol. 23, no. 1, pp. 1-15, 1986

Authors: Abe, K. | Takano, Y. | Oka, S.

Article Type: Research Article

Abstract: The expression for the sedimentation rate in inclined tubes given by Nakamura et al (Nakamura, H. and Kuroda, K. Keijo J. Med. 8, 256–296, 1937) is improved to be applicable to the problem that the falling velocity of a particle from the top wall of the tube v ′ differs from the one from the interface between the particle free layer and the suspended layer v . The effects of the shape at the bottom of the tube and the increase in height of the layer closely packed with particles are taken into account.

Keywords: Inclined tube, Erythrocyte, Sedimentation rate

DOI: 10.3233/BIR-1986-23102

Citation: Biorheology, vol. 23, no. 1, pp. 17-23, 1986

Authors: Grigg, C.H. | Fitz-Gerald, J.M.

Article Type: Research Article

Abstract: An acinus is the principal secretion unit of an exocrine gland. This paper sets up a mathematical model of an acinus and examines the effect on the output of varying the operating parameters, both of the secretion mechanism and the fluid properties. Particular reference is made to acini of the pancreas. The question of whether the effects of cystic fibrosis on the pancreas can be attributed to the increased viscosity of the exudate is also considered. The work identifies key parameters, and their quantitative ranges, which would need to be examined experimentally in order to resolve this question.

Keywords: secretion, pancreas, exocrine, mathematical model, acinus, cystic fibrosis

DOI: 10.3233/BIR-1986-23103

Citation: Biorheology, vol. 23, no. 1, pp. 25-50, 1986

Authors: Bitoun, J.P. | Bellet, D.

Article Type: Research Article

Abstract: A theoretical and experimental study concerning two-component fluid pulsating flow through cylindrical ducts having a slight constriction is presented. The model corresponds to blood flows through small diameter vessels (smaller than 400 μ m) affected by a singular stenosis. The theoretical approach is based on a asymptotical expansion of the stream function. The physical hypotheses used were based on findings from simultaneous visualization methods. The influence of geometrical, hydrodynamical and structural parameters is systematically examined and related to velocity profiles, hydrostatic pressure, surface stresses.

Keywords: Hemodynamics, microcirculation, plasmatic layers, stenosis, hematocrit rate, Taylor law

DOI: 10.3233/BIR-1986-23104

Citation: Biorheology, vol. 23, no. 1, pp. 51-61, 1986

Authors: McMillan, D.E. | Utterback, N.G. | Nasrinasrabadi, M. | Lee, M.M.

Article Type: Research Article

Abstract: The rheology of blood is characterized by shear thinning, viscoelasticity, and thixotropy. Its rheological evaluation is usually accomplished using a torque balance technique during rotational viscometry. Because a stable torque balance does not develop instantly, studies of thixotropy and viscoelasticity of blood have usually been carried out only at low shear rate where their development is slow enough to be monitored accurately. The torque balance technique may be converted from static to dynamic by incorporating the rate of change of sensing system angular momentum. We have modified our Couette viscometer, adding a computer-controlled stepping motor and a second digital voltmeter. …The latter is used to determine the angular position of the sensing system every 25 or 50 msec. The new approach allows rapid observation of the development and disappearance of shear stress, enabling us to examine the transient behavior of blood at moderate shear rate (1 to 100 inverse seconds). The transient flow behavior of blood at moderate shear rate is most easily compared directly with the behavior of Newtonian fluids. We present information about the response of our system using a torque balance observation rate of 20 per second. Blood’s viscoelasticity is observed to fall substantially as shear rate rises, while its thixotropic transient excess stress rises steadily with increasing shear rate. Show more

Keywords: hemorheology, viscoelasticity, thixotropy, blood viscosity

DOI: 10.3233/BIR-1986-23105

Citation: Biorheology, vol. 23, no. 1, pp. 63-74, 1986

Authors: Abe, K. | Takano, Y. | Sakanishi, A.

Article Type: Research Article

Abstract: To discuss the relaxation phenomena of bioligical cell suspensions, we calculate the complex intrinsic viscosity of dispersions of spherical cells with viscoelastic membrane as a function of the frequency taking account of interfacial tension at both the interfaces of the membrane. The Maxwell model and two kinds of the three- parameter models are used to describe the viscoelasticity of the cell membrane. The results are computed mainly for the Maxwell model similarly in case of the Voigt Model (Abe, K., Takano, Y. and Sakanishi, A. Biorheology 21 405-414, 1984). The computed results of the four models, the Voigt, the Maxwell …and the two kinds of the three-parameter viscoelastic models, are compared with the experimental data. Show more

Keywords: viscoelasticity, suspension, cell, viscoelastic membrane, maxwell model, three-parameter viscoelastic model

DOI: 10.3233/BIR-1986-23106

Citation: Biorheology, vol. 23, no. 1, pp. 75-87, 1986