Influence of fibrinogen on flow properties of erythrocyte suspensions

1964 ◽  
Vol 207 (5) ◽  
pp. 1035-1040 ◽  
Author(s):  
Roe E. Wells ◽  
Thomas H. Gawronski ◽  
Paul J. Cox ◽  
Richard D. Perera
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Cell Aggregation ◽  
Cell Suspensions ◽  
Fibrinogen Concentration ◽  
Sedimentation Rates ◽  
Cell Aggregates ◽  
Red Cell ◽  
Flow Properties ◽  
Yield Value

The influence of fibrinogen on the flow properties of red cell suspensions (hematocrit 41) was studied by viscometry at low rates of shear (0.1–20 sec–1). These findings were correlated with sedimentation rates and photomicrographical studies of cell aggregation. Fibrinogen concentration was varied from 0.3 to 2.0 g/100 ml. The viscosity of the pure solutions of fibrinogen was independent of shear rate, ranging from 0.87 to 1.7 centipoise (cp) at 37 C. The viscosity of the cell suspensions at 10 sec–1 varied from 4.3 cp in 0.3 g/100 ml fibrinogen to 14 cp in 2 g/100 ml fibrinogen. All suspensions were markedly dependent on shear rate, viscosity increasing in exponential-like fashion as shear rate decreased. Extrapolation of plots of shear stress1/2 versus shear rate1/2 revealed the suspensions to sustain a finite stress without deformation or flow, the "yield value" increasing as fibrinogen concentration increased. Photomicrographs of dilute cell suspensions revealed the formation of cell aggregates and rouleaux, increasing in size and descent velocity as fibrinogen concentration increased.

Rheology and structure of blood suspensions

1964 ◽  
Vol 19 (1) ◽  
pp. 127-133 ◽  
Author(s):  
S. E. Charm ◽  
W. McComis ◽  
G. Kurland
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Structural Model ◽  
Cell Suspensions ◽  
Rate Curve ◽  
Red Cell ◽  
Shear Rates ◽  
Straight Line ◽  
Rate Plot

A structural model developed for kaolin suspensions was applied to blood in order to determine the structure and strength of the red cell suspensions. The yield stress of red cell suspensions determined in settling experiments agreed with the yield stress determined from shear stress-shear rate information employing Casson's equation. Theoretical considerations indicate that the shear stress-shear rate curve for blood should approach a straight line. This was found to be true at shear rates above 40 sec-1. The slope of this line was predicted from calculations based on sedimentation experiments and a modified Einstein's equation. The data suggest that the curvature of the shear stress-shear rate plot at low shear rates is due to aggregates of cells which break down under increasing shear rate, resulting finally in individual flocs. It is suggested that a floc consists of one to four cells with adhering plasma. The aggregate was calculated to have twice as much plasma associated with it as does a floc. However, the size of the aggregate could not be determined since the number of flocs associated with an aggregate could not be determined. shear stress-shear rate curve; red cell floc; red cell aggregate; sedimentation rate; blood viscosity and flow Submitted on February 28, 1963

Effects on Erythrocyte Aggregation and Blood Coagulation from Iohexol Solutions with and without Sodium Chloride

1995 ◽  
Vol 36 (2) ◽  
pp. 204-209
Author(s):  
C.-M. Chai ◽  
T. Almén ◽  
P. Aspelin ◽  
L. Bååth
Keyword(s):  
Sodium Chloride ◽  
Blood Coagulation ◽  
Glucose Solution ◽  
Cell Aggregation ◽  
Test Solution ◽  
Erythrocyte Aggregation ◽  
Cell Aggregates ◽  
Red Cell ◽  
Red Blood Cell Aggregation ◽  
Osmotic Effects

Solutions of the nonionic monomeric contrast medium iohexol (300 mg I/ml) with and without added NaCl were investigated for effects on red blood cell aggregation and blood coagulation. Three volumes of a test solution were mixed in test tubes with one volume of human blood. During 30 min samples of the mixture were taken for investigation. Six test solutions were used: 1) iohexol, 2) iohexol+glucose 280 mM, 3) iohexol+NaCl 150 mM, 4) glucose 280 mM, 5) glucose 140 mM+NaCl 75 mM, 6) NaCl 150 mM. Test solutions with NaCl caused no aggregation. Test solutions without NaCl always caused macroscopic red cell aggregates. These aggregates always disappeared when saline was added to the sample. The macroscopic red cell aggregates could be dispersed to microscopic aggregates by shaking the test tubes. During the next 30 min macroscopic aggregates returned in the glucose solution but not in the iohexol solutions. In 30 min, blood mixed with iohexol solutions never coagulated while blood layered on top of the same iohexol solutions always coagulated. Blood mixed with solutions 5 and 6, both without iohexol, always coagulated. It is concluded that adding 150 mM NaCl to iohexol did not eliminate its ability to antico-agulate whole blood, but inhibited its ability to aggregate red cells. This inhibition was not caused by the osmotic effects of the added NaCl.

scholarly journals Rheological properties of liquid ebonite compositions filled with shungite

2021 ◽  
pp. 65-70
Author(s):  
Y.M. Pushkarev ◽  
◽  
S.V. Saitarly ◽  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Viscous Flow ◽  
Rheological Properties ◽  
Flow Properties

The effect of shungite on the structural and viscous-flow properties of compositions based on oligobutadiene was studied. The strength of coagulation structures of ebonite compositions filled with shungite was determined. The critical filling concentration was established and it is 40 wt.% of shungite per 100 wt.% of oligobutadiene. It was shown that increasing the temperature from 200C to 800C leads to a significant reduction in the shear stress required to destroy the structure of the composition. Temperature and shear rate independently affect the structured composition. Thus, it was shown that shungite powder can be used as a filler in liquid ebonite compositions based on oligobutadiene.

Hematologic Findings in the Total Body X-irradiated Hamster

Blood ◽  
1954 ◽  
Vol 9 (6) ◽  
pp. 622-631 ◽  
Author(s):  
GEORGE P. FULTON ◽  
DAVID L. JOFTES ◽  
ROMA KAGAN ◽  
BRENTON R. LUTZ
Keyword(s):  
Mast Cells ◽  
Total Body Irradiation ◽  
Peripheral Circulation ◽  
Sedimentation Rates ◽  
Cell Aggregates ◽  
Red Cell ◽  
Cardiac Blood ◽  
Total Body ◽  
Venular Endothelium ◽  
Visual Observations

Abstract Hematologic determinations were made on cardiac blood from normal hamsters and from four groups of hamsters at daily intervals after total body irradiation with 600 r, 1000 r, 1200 r and 1500 r. Pancytopenia, lowered hematocrit, and decreased hemoglobin occurred. The clotting times were extended in the 1200 r and 1500 r groups, and this defect was correlated temporally with thrombocytopenia and disrupted mast cells. The sedimentation rates were increased terminally in the lethally-irradiated hamsters. The significance of these findings and the relationships to visual observations on the peripheral circulation such as leukocytic pavements on capillary and venular endothelium, platelet thromboembolic phenomena, erythrocytic extravasations, and circulating red cell aggregates are discussed.

The flow characteristics of halloysite suspensions

Clay Minerals ◽  
1995 ◽  
Vol 30 (2) ◽  
pp. 99-106 ◽  
Author(s):  
B. K. G. Theng ◽  
N. Wells
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Particle Shape ◽  
Flow Characteristics ◽  
Linear Increase ◽  
Point Of Zero Charge ◽  
Particle Interactions ◽  
Yield Value ◽  
Edge Surface ◽  
Rotary Viscometer

AbstractThe rheology of aqueous suspensions of Na halloysites with different particle shape has been investigated using a Haake rotary viscometer. Three halloysites from New Zealand were used: Matauri Bay (MB), Te Akatea (TA) and Opotiki (Op) which are mainly composed of thick long tubules, short thin laths, and spherules, respectively. Suspensions of the materials subsequently prepared from the MB and TA samples show a pseudoplastic consistency under shear, characterized by a steep initial rise in shear stress as shear rate increases, followed by a linear increase in stress when a certain shear rate is exceeded. The Op halloysite, on the other hand, shows Newtonian flow behaviour for which shear stress increases linearly with shear rate throughout. For MB and TA, the shear stress developed during rotor acceleration is larger than that produced during deceleration, and the corresponding flow curves enclose a hysteresis loop. As suspension pH increases, the pseudoplastic character decreases as does the amount of hysteresis. Above pH 7.5, flow approaches Newtonian and hysteresis is absent. Plots of Bingham yield value against pH at different ionic strengths (0.003, 0.03 and 0.3 M NaCl) intersect at pH 6.0 for MB and at pH 7.1 for TA. These values are identified with the point of zero charge (PZC) of the particle edge surface. The flow characteristics of halloysites may be explained in terms of the influence of particle shape, pH, electrolyte concentrations, and layer composition on particle interactions.

Time Dependent Rheological Characteristics of Pineapple Jam

2007 ◽  
Vol 3 (3) ◽  
Author(s):  
Santanu Basu ◽  
US Shivhare ◽  
GSV Raghavan
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Time Dependent ◽  
Rheological Characteristics ◽  
Fruit Pulp ◽  
Flow Properties ◽  
Thixotropic Behavior ◽  
Dependent Flow

Jam is an intermediate moisture food containing fruit pulp, pectin, sugar and acid. The effect of sugar and pectin concentration, pH, shear rate and temperature on the time dependent rheological properties of pineapple jam was studied using a rheometer. Pineapple jam exhibited thixotropic behavior. Shear stress of the pineapple jam at a particular time of shearing depended on the shear rate, temperature and composition. Weltman, Hahn, and Figoni and Shoemaker, models were applied to describe the time dependent flow properties of pineapple jam. Hahn model described adequately the rheological characteristics of pineapple jam.

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