Rheology of blood

1962 ◽  
Vol 202 (6) ◽  
pp. 1188-1194 ◽  
Author(s):  
L. C. Cerny ◽  
F. B. Cook ◽  
C. C. Walker
Keyword(s):  
Shape Factor ◽  
Flow Behavior ◽  
Flow Equation ◽  
Capillary Viscometer ◽  
Shear Stresses ◽  
Red Cell ◽  
Newtonian Flow ◽  
Wide Range ◽  
Citrate Dextrose

The non-Newtonian flow properties of resuspended red cells were determined in vitro by means of a capillary viscometer. In order to evaluate the rheological effect of the suspending medium, viscosity measurements were made over a wide range of shearing stresses using both plasma and an acid-citrate-dextrose solution as diluents. At low shearing stresses, the plasma exhibited non-Newtonian flow behavior. Using a technique of treating the data to obtain rate-of-shear versus shearing-stress curves without prior assumption of a flow equation showed that whole blood over a wide range of shear stresses and a twofold range of capillary radii did not show any dependence of the viscosity on the capillaries employed. This procedure was also used to examine the data of other workers. In an attempt to determine the shape factor for the red cell, an extrapolation to infinite dilution and zero rate of shear was made. The shape factor can be estimated to be 2.5±1.5 for red cell.

The Significance of Rheology in Rubber Processing. 2. Studies of Latex

1959 ◽  
Vol 32 (4) ◽  
pp. 1050-1061
Author(s):  
Kurt Edelmann ◽  
Edith Horn
Keyword(s):  
Rheological Behavior ◽  
Flow Behavior ◽  
Flow Equation ◽  
Shear Stresses ◽  
Gel Structure ◽  
Newtonian Flow ◽  
Flow Curves ◽  
General Flow ◽  
Thixotropic Behavior ◽  
Measurable Range

Abstract After referring to the importance of rheological studies for the ever growing applications of latex in industry, results are reported for the study of the rheological behavior of several Buna latexes, using a Höppler Rheo-viscometer. The flow curves obtained in this way show a different type of non-Newtonian flow from solutions of rubber. The region of η0, viscosity at rest, is absent. With increasing velocity gratient, the viscosity becomes smaller and smaller and finally reaches a constant value at a relatively high velocity gradient. That is, non-Newtonian flow passes gradually over into Newtonian flow. For those latexes whose Newtonian flow lies within the measurable range, a general flow equation is given which includes the Newtonian portion of the shear stress together with a stress correction. This equation of flow can be used to define the rheological behavior of the latexes. The cause of this type of rheological behavior is found in the thixotropic properties of the latex system. If a Höppler Rheo-viscometer is used and measurements are made first at increasing and then at decreasing shear stresses, the plotted data show a hysteresis loop which is evidence of thixotropy. With those latex systems for which the Newtonian flow behavior falls within the limits of the measurements, and whicn can be called fluids, the viscosities measured with decreasing shear stresses lie below those which are measured with increasing shear stresses. On the other hand, highly concentrated latexes which can be considered as having a gel structure throughout, such as the 70% Buna-Latex S3 used in this work, display a different kind of thixotropic behavior. In such cases, the viscosities measured with decreasing stresses are higher than those measured with increasing shear stresses. A different flow equation is needed to define this different type of thixotropy.

Non-Newtonian Flow of Polymer Solutions

1966 ◽  
Vol 39 (5) ◽  
pp. 1411-1420
Author(s):  
F. Patat ◽  
G. Spott
Keyword(s):  
Polymer Solutions ◽  
Flow Behavior ◽  
Capillary Viscometer ◽  
Poly Ethylene Glycol ◽  
Newtonian Flow ◽  
Rotational Viscometer ◽  
Weight Concentration ◽  
Polymer Interactions ◽  
Poly Ethylene ◽  
Degree Of Association

Abstract Non-Newtonian flow of solutions of polyisobutylene, poly (vinyl acetate), poly (ethylene glycol), and polyisoprene was investigated, as a function of molecular weight, concentration, temperature, and solvent, with a modified rotational viscometer with coaxial cylinders and a newly-developed, high-pressure, capillary viscometer. Analysis of the results of the viscosity experiments was based upon kinematic flow theory, and provided a consistent interpretation of the non-Newtonian flow behavior encountered. Shape of the flow curve is determined by the decreasing degree of association of the polymers with increasing shear stress. Rise in viscosity of the polymer solutions, as compared to that of the solvent, is due chiefly to solvent associated polymer interactions at each stress state involved.

scholarly journals Characterization of the Bulk Flow Properties of Industrial Powders from Shear Tests

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 540
Author(s):  
Domenico Macri ◽  
Roberto Chirone ◽  
Hamid Salehi ◽  
Daniele Sofia ◽  
Massimiliano Materazzi ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Bulk Flow ◽  
Shear Stresses ◽  
Flow Properties ◽  
Wide Range ◽  
Non Linear ◽  
Shear Cells ◽  
Best Fitting ◽  
Yield Loci ◽  
Experimental Values

Bulk flow properties from shear analysis of compacted powders can be evaluated following different approaches. Experimental values of shear stresses obtained by conventional shear cells are traditionally used to build yield loci, from which the most relevant flow properties could be found. Such flow properties play an important role in determining their performance under fluidization conditions. In this work, a useful app, named cYield, was developed by using the new Matlab’s App Developer environment. This tool enables users to calculate both linear (Coulomb) and non-linear (Warren–Spring) yield loci as the best fitting of the σ-τ experimental shear points. It also provides a wide range of statistical information related to the quality of the outcomes obtained. The different features of the tool are presented, and the crucial steps for the execution of its calculations are illustrated. Moreover, it has been applied for the yield loci analysis of four different materials traditionally used in manufacturing processes. The results confirm that the flow behavior of many industrial powders, especially if cohesive, is better described by a non-linear yield locus.

NOVEL TECHIQUES FOR QUANTIFICATION OF RBC-SHAPE (RS) AND SHEAR INDUCED RBC ELONGATION (SIRE): APPLICATION FOR ANALYSIS OF DRUG INDUCED ALTERATIONS

1987 ◽  
Author(s):  
G Artmann ◽  
R Grebe ◽  
H Wolff ◽  
R Degenhardt ◽  
H Schmid-SchÖnbein
Keyword(s):  
Membrane Curvature ◽  
Low Flow ◽  
Shear Stresses ◽  
Red Cell ◽  
Drug Induced ◽  
Cell Deformability ◽  
Red Cell Deformability ◽  
Red Cell Membrane ◽  
Filtration Method

In the past, red cell resting shape could only be assessed by subjective scaling, red cell deformability by a variety of rheological tests that are extremelydifficult to standardize and which all subject the RBC to high deforming forces. None of the latter have been accepted as reference in haematology, haemorheologyor pharmacology. A recent development from our group now allows objective, numerical analysis of red cell membrane curvature (i.e. the echinocytic or stomatocytic deviation from the discocytic resting shape) by a tangent count procedure in optical sections through freely suspended, randomly oriented RBC: (Grebe et al. Biorheology 22(6), 1985). Also, the deformation of point attached erythrocytes under the influence of extremely low shear stresses (0.05 Pa to 0.5 Pa, ARTOANN:Clin. Hemorheology 6, 1986), which are at least two orders of magnitude lower thanthat in any routinely available filtration method allows for the first time to model in vitro the extreme low flow states that occur in severe forms of haemodynamic insufficiency. These two methods in combination are ideally suited for routine tests of drug effects on normal human RBC: the drug action on RS can be monitored continuously during the action of drugs in the suspending medium; likewise, RISA can be recorded automatically on one population of adherent RBC while altering the composition and the drug concentration in the superfusate. The two methods were applied in combination to test rheological and membranological effects of two distinctly different compounds, namely Bencyclan (Bencylan-Hydrogen-Fumarate) and Vinpocitin (Aethyl vincamin) in normal cells and in cells after exposure to "stress conditions", i.e. hyperosmolarity and lactacidosis. Both olrugs given to n o r m a 1 RBC produce stomatocytosis in a done dependent fashion (1-100 uMolar). At shear stresses above o.6 Pa, the RISA is identical to controls, but is oxmsiderably less pronounced at lower shear stresses (T < 0.2 Pa). Thus, drugs of completely olifferent pharmacological action produce clear cut rheological effects on RBC in the micrcmolar concentration range; the combination of methods employed opens new possibilities for the systematic development of haemorheologically active drugs.Supported by DFG:Grant Gr 902/1-1

A new capillary viscometer for small samples of whole blood

2002 ◽  
Vol 216 (6) ◽  
pp. 385-392 ◽  
Author(s):  
G N Marinakis ◽  
J C Barbenel ◽  
S G Tsangaris
Keyword(s):  
Whole Blood ◽  
Small Samples ◽  
Capillary Viscometer ◽  
Shear Stresses ◽  
Test Volume ◽  
Shear Rates ◽  
Sucrose Solutions ◽  
Wide Range ◽  
Small Test ◽  
Good Agreement

A new capillary viscometer is described in which a column of blood is discharged under a constant pressure, producing a variety of shear stresses during a single test. Measurement of the viscosity of Newtonian sucrose solutions showed good agreement between the viscosity determined from the new system and the expected values. The viscosity of whole blood was measured in a cone-and-plate viscometer at a wide range of shear rates and characterized using a power law model; good agreement was obtained between the capillary and rotational results at low and medium shear rates. High shear rate results could also be obtained by increasing the driving pressure. The new viscometer proved to be simple to use, utilized a small test volume and produced reliable results.

Red cell magnesium in rainbow trout

1988 ◽  
Vol 66 (4) ◽  
pp. 929-933
Author(s):  
A. H. Houston ◽  
J. D. Gray
Keyword(s):  
Magnesium Content ◽  
Magnesium Concentration ◽  
Equilibrium Potential ◽  
Red Cell ◽  
High Potassium ◽  
High Sodium ◽  
Wide Range ◽  
Plasma Magnesium

In vivo erythrocytic magnesium concentration was significantly correlated with red cell potassium level and potassium equilibrium potential, but not with specimen weight, plasma magnesium, red cell sodium and chloride, or chloride equilibrium potential. To examine the relationship between magnesium and potassium, potassium levels were manipulated in vitro with catecholamine, furosemide, ouabain, and valinomycin. Over a wide range of normal and supranormal potassium concentrations, a significant correlation between magnesium and potassium levels was evident. However, depletion of potassium following exposure to ouabain and valinomycin led to a shift from the normal high potassium/low sodium relationship to a high sodium/low potassium state with progressive increases in magnesium content. Correlation of magnesium with potassium was lost, and a significant correlation with red cell sodium, but not with sodium equilibrium potential, was evident. Red cell magnesium concentration appears, therefore, to be influenced by the preponderant univalent cellular cation rather than potassium per se.

scholarly journals Studies on the Survival of Incompatible Cells in Patients with Hypogammaglobulinemia

Blood ◽  
1959 ◽  
Vol 14 (1) ◽  
pp. 24-36 ◽  
Author(s):  
HUGH CHAPLIN
Keyword(s):  
Paper Electrophoresis ◽  
In Vitro Tests ◽  
Antibody Activity ◽  
In Vitro Test ◽  
Red Cell ◽  
Survival Times ◽  
Wide Range ◽  
Group B

Abstract 1. Four adult patients are described whose sera showed a complete lack of gamma globulin by paper electrophoresis. 2. All four patients might have been considered "universal recipients" because of the absence of isohemagglutinins on routine laboratory tests. 3. Weak isohemagglutinins were detectable in the sera from three of the four subjects when the sensitivity of the in vitro test was increased. 4. Following intravenous administration of 4 ml. of ABO-incompatible cells, red cell survival was shortened in all of the patients, with a wide range of half-survival times from <10 minutes to as long as 9 days. 5. Although in vitro tests for antibody activity revealed no qualitative differences among the sera from the three patients with detectable isohemagglutinins, two different mechanisms of red cell removal were observed, one which entailed nearly equal activity by both liver and spleen, the other being primarily a function of the spleen. 6. The survival of incompatible cells under conditions of antibody "excess" and antibody "insufficiency" was compared in one of the patients. The findings emphasize the sensitivity of in vivo survival studies employing small volumes of incompatible cells to detect minute quantities of circulating antibody. 7. A fall in anti-A titer following the administration of group B cells to one hypogammaglobulinemic subject is interpreted as a possible in vivo example of the absorption of "cross-reacting" antibody in the ABO system. 8. In the light of the in vivo and in vitro findings, none of the 4 hypogammaglobulinemic patients in the present series could be categorized as "universal recipients."

Dynamic Association between Artery Shear flow Condition and Platelet Cytosolic Free Ca2+ Concentration in Human Hypertension

1990 ◽  
Vol 79 (6) ◽  
pp. 613-618 ◽  
Author(s):  
Jaime Levenson ◽  
Marie-Aude Devynck ◽  
Isabelle Pithois-Merli ◽  
Kim Hanh Le Quan Sang ◽  
Vincenzo Filitti ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Vascular Endothelial Cells ◽  
Cell Metabolism ◽  
Shear Stresses ◽  
Double Blind ◽  
Wide Range ◽  
Membrane Stretching ◽  
Positive Correlations

1. Blood cells and vascular endothelial cells are subjected to a wide range of haemodynamically generated shear stress forces. In vitro, membrane stretching or shear stress have been observed to activate ion channels and cell metabolism and to facilitate erythrocyte and platelet aggregation. 2. The present study was designed to evaluate the participation of shear stresses in the control of apparent platelet cytosolic free Ca2+ concentration in hypertensive patients. 3. Shear conditions and platelet cytosolic free Ca2+ concentration in vitro were studied after a dynamic perturbation induced by 3 months of double-blind treatment with one of two β-antagonists, carteolol and atenolol. Brachial artery wall shear rate and stress were estimated by means of a pulsed Doppler velocimeter, and blood viscosity was measured by a co-axial viscometer at a shear rate of 96 s−1. Platelet cytosolic free Ca2+ concentration was simultaneously measured by using the Quin-2 fluorescent chelator. The direct effect of atenolol and carteolol on platelet cytosolic free Ca2+ concentration in vitro was also measured after addition of the β-blockers to plateletrich plasma. 4. Atenolol and carteolol decreased blood pressure similarly but their effects on shear rate (P < 0.02), shear stress (P < 0.01) and platelet cytosolic free Ca2+ concentration (P < 0.05) differed after 3 months of therapy. In contrast, neither of the drugs significantly altered platelet cytosolic free Ca2+ concentration, in vitro per se. 5. In the overall population, strong positive correlations existed not only between changes in platelet cytosolic free Ca2+ concentration and those in shear rate (r = 0.81, P < 0.001) and shear stress (r = 0.83, P < 0.001), but also between their absolute values, suggesting a possible haemodynamic shear-dependent modulation of transmembrane Ca2+ transport.

scholarly journals IDENTIFICATION OF RHEOLOGICAL PROPERTIES OF POLY(ETHYLENE OXIDE) – WATER SOLUTIONS

2020 ◽  
Vol 63 (9) ◽  
pp. 82-87
Author(s):  
Ryszard Wójtowicz ◽  
Katarzyna Kocewiak ◽  
Andrey A. Lipin
Keyword(s):  
Ethylene Oxide ◽  
Rheological Properties ◽  
Flow Behavior ◽  
Newtonian Fluids ◽  
Shear Stresses ◽  
Water Solutions ◽  
Marquardt Algorithm ◽  
Wide Range ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

In the paper results of investigations of rheological properties for selected PEO-water solutions are presented. On the basis of measurements, carried out with use of rotational viscosimeter values of shear stresses were determined in the relatively wide range of shear rates. Rheological curves were described by the Ostwald de Waele model (or so-called power-law). The model coefficients such as the fluid consistency coefficient k and the flow behavior index n were determined using Levenberg−Marquardt algorithm for nonlinear estimation. The influence of temperature on properties and behavior examined non-Newtonian fluids was also determined. Results were processed in the curve shift parameter at. Experiments shown a significant effect of poly(ethylene oxide) concentration cPEO on rheological properties of examined solutions. For the lowest concentration (cPEO=1.2%) solutions exhibited properties similar to Newtonian fluids with values of n close to 1. With increasing of PEO concentration in water (cPEO=2.4-4.8%), solutions exhibited properties as non - Newtonian fluids, pseudoplastic, without yield limit. In these cases values of n were below unity and for the highest concentration (cPEO=4.8%) belonged to the range of n=0.5694-0.7536, depending on the temperature. Results of investigations can be used during numerical simulations, design and optimization of industrial equipment, working with fluids of this kind, including mixing vessels, columns or heat exchangers.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

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