F26. Square root relation between shear stress of blood clotting and time investigated by rotational viscometer

Biorheology ◽  
1995 ◽  
Vol 32 (2-3) ◽  
pp. 230-231
Author(s):  
F LIAO ◽  
R LIAO ◽  
W LI
Keyword(s):  
Shear Stress ◽  
Blood Clotting ◽  
Square Root ◽  
Rotational Viscometer ◽  
Root Relation

ENTROPY INFLUENCE ON THE DEPENDENCE OF THE NANOFLUIDS VISCOSITY ON TEMPERATURE AND SHEAR RATE

2021 ◽  
Vol 7 (3) ◽  
pp. 89-105
Author(s):  
Lyudmila P. SEMIKHINA ◽  
Daniil D. Korovin
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Viscous Flow ◽  
High Reliability ◽  
Narrow Particle Size Distribution ◽  
Disperse Systems ◽  
Rotational Viscometer ◽  
Surfactant Micelles ◽  
Dispersed Systems

A Brookfield DV-II + Pro rotational viscometer was used to study the viscosity of 7 samples of concentrated nanodispersed systems (nanofluids) with a similar viscosity (6-22 mPa ∙ s), the particles of the dispersed phase in which are nanosized surfactant micelles and conglomerates from them. It was found that for 5 out of 7 studied reagents, there is a decrease in viscosity typical for dispersed systems with an increase in the shear rate, and their flow curves, that is, the dependence of the shear stress on the shear rate, correspond to the ideal plastic flow of non-Newtonian fluids. Moreover, with high reliability, R2 ≥ 0.999 is described by the Bingham equation with a small value of the limiting shear stress (less than 0.2 Pa). It is shown that all the studied reagents are also characterized by an increase in the activation energy of a viscous flow Е with an increase in the shear rate. As a result, a decrease in viscosity with an increase in shear rate, typical for disperse systems, including nanofluids, is provided by a more significant increase in entropy changes ΔS compared to Е. It has been substantiated that, depending on the ratio between the activation energy of viscous flow Е and the change in entropy ΔS, the viscosity of concentrated micellar dispersed systems with an increase in the shear rate can decrease, remain unchanged, and increase. The last two cases, not typical for disperse systems and nanofluids, were identified and studied using the example of two demulsifiers, RIK-1 and RIK-2, with a maximum of a very narrow particle size distribution at 160 ± 5 nm, corresponding to the size of a special type of very stable micelles Surfactant — vesicle.

ESTIMATION OF CRITICAL SHEAR STRESS OF SEDIMENT USING ROTATIONAL VISCOMETER

2021 ◽  
Vol 77 (2) ◽  
pp. I_1039-I_1044
Author(s):  
Shinya NAKASHITA ◽  
Kyeongmin KIM ◽  
Yuki IMAMURA ◽  
Tadashi HIBINO
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Rotational Viscometer

scholarly journals Platelet Aggregation Induced by a Monoclonal Antibody to the A1 Domain of von Willebrand Factor

Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3792-3799 ◽  
Author(s):  
Hilde Depraetere ◽  
Nadine Ajzenberg ◽  
Jean-Pierre Girma ◽  
Catherine Lacombe ◽  
Dominique Meyer ◽  
...  
Keyword(s):  
Shear Stress ◽  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Inhibitory Effect ◽  
Platelet Glycoprotein ◽  
Rotational Viscometer ◽  
Induce Platelet Aggregation ◽  
Static Conditions ◽  
Von Willebrand ◽  
Willebrand Factor

Shear-induced platelet aggregation (SIPA) involves von Willebrand Factor (vWF) binding to platelet glycoprotein (GP)Ib at high shear stress, followed by the activation of αIIbβ3. The purpose of this study was to determine the vWF sequences involved in SIPA by using monoclonal antibodies (MoAbs) to vWF known to interfere with its binding to GPIb and to αIIbβ3. Washed platelets were exposed to shear rates between 100 and 4,000 seconds−1 in a rotational viscometer. SIPA was quantitated by flow cytometry as the disappearance of single platelets (DSP) in the sheared sample in the presence of vWF, relative to a control in the absence of shear and vWF. At a shear rate of 4,000 seconds−1, DSP was increased from 5.9% ± 3.5% in the absence of vWF to 32.7% ± 6.3% in the presence of vWF. This increase in SIPA was not associated with an elevation of P-selectin expression. vWF-dependent SIPA was completely abolished by MoAb 6D1 to GPIb and partially inhibited by MoAb 10E5 to αIIbβ3. Three MoAbs to vWF were compared for their effect on SIPA at 4,000 seconds−1 in the presence of vWF: MoAb 328, known to block vWF binding to GPIb in the presence of ristocetin, MoAb 724 blocking vWF binding to GPIb in the presence of botrocetin, and MoAb 9, an inhibitor of vWF binding to αIIbβ3. Similar to the effect of MoAb 6D1, MoAb 328 completely inhibited the effect of vWF, whereas MoAb 9 had a partial inhibitory effect, as MoAb 10E5 did. In contrast, MoAb 724, as well as its F(ab′)2 fragments, promoted shear-dependent platelet aggregation (165% of the DSP value obtained in the absence of MoAb 724), indicating that MoAb 724 was responsible for an enhanced aggregation, which was independent of binding to the platelet Fcγ receptor. In addition, the enhancement of aggregation induced by MoAb 724 was abrogated by MoAb 6D1 or 10E5 to the level of SIPA obtained in the presence of vWF incubated with a control MoAb to vWF. Finally, the activating effect of MoAb 724 was also found under static conditions at ristocetin concentrations too low to induce platelet aggregation. Our results suggested that on binding to a botrocetin-binding site on vWF, MoAb 724 mimics the effect of botrocetin by inducing an active conformation of vWF that is more sensitive to shear stress or to low ristocetin concentration.

Analysis of Thrombus Formation Process by Flow Induced High Shear Rate Using Optical Observation Method

2013 ◽  
Author(s):  
Masaaki Tamagawa
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Formation Process ◽  
Thrombus Formation ◽  
Laser Sheet ◽  
Formation Rate ◽  
High Shear Rate ◽  
Square Root ◽  
High Shear ◽  
Observation Method

This paper describes visualization of thrombus formation process on orifice flows by laser sheet beam and normal illumination. The aim is to investigate the effects of shear stress or shear rate on the thrombus formation or thrombus formation rate. It was found that the white thrombus formation rate is proportional to square root of shear rate, and the white thrombus is dominant when the shear rate is more than 450 (1/s).

Effect of Lattice Disorder on the Line Shape of NMR Spin Echo Signals

1969 ◽  
Vol 24 (3) ◽  
pp. 332-336 ◽  
Author(s):  
M Mehring ◽  
O Kanert
Keyword(s):  
Shear Stress ◽  
Dislocation Density ◽  
Single Crystals ◽  
Point Defects ◽  
Line Shape ◽  
Spin Echo ◽  
Square Root ◽  
Lattice Disorder ◽  
Line Shapes ◽  
The Mean

Abstract The spin echo line shapes of Rb87 and Br79.81 have been measured in undeformed and plasti­cally deformed RbBr single crystals. Analysis of the line shape of the measured echoes shows that the quadrupolar part of the echoes is given by point defects in the case of undeformed crystals, whereas in deformed crystals this term is determined by dislocations. A quantitative evaluation of the width of the quadrupolar shape yields the mean dislocation density in the samples as a function of the shear stress acting during the deformation. It was found that the square root of the dislocation density is proportional to the shear stress.

scholarly journals The effect of PGI2 and theophylline on the response of platelets subjected to shear stress

Blood ◽  
1981 ◽  
Vol 58 (4) ◽  
pp. 678-681 ◽  
Author(s):  
RA Hardwick ◽  
JD Hellums ◽  
DM Peterson ◽  
JL Moake ◽  
JD Olson
Keyword(s):  
Shear Stress ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agent ◽  
Human Platelets ◽  
Clinical Applications ◽  
Serotonin Release ◽  
Large Reduction ◽  
Prior Work ◽  
Rotational Viscometer

A specially designed rotational viscometer was used to investigate the effects of the antiplatelet agent PGI2 in combination with theophylline on the response of human platelets subjected to shear stress. Samples of citrated platelet-rich plasma (PRP) were exposed to shear stress in the viscometer for a period of 5 min at 23 degrees C. The levels of stress studied ranged from 50 to 300 dynes/sq cm. Pretreatment of the platelets with 0.01 microM PGI2 and 500 microM theophylline before exposure to shear stress caused a large reduction in shear-induced platelet aggregation. However, it was also observed that the PGI2-- theophylline pretreatment concomitantly caused a large increase in shear-induced platelet lysis and serotonin release at stress levels equal to or greater than 150 dynes/sq cm. This observed increase in platelet fragility may have important implications for clinical applications of PGI2. The results are discussed and compared to those obtained in prior work in which platelets were pretreated with acetylsalicylic acid or with PGE1.

scholarly journals Platelet Aggregation Induced by a Monoclonal Antibody to the A1 Domain of von Willebrand Factor

Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3792-3799 ◽  
Author(s):  
Hilde Depraetere ◽  
Nadine Ajzenberg ◽  
Jean-Pierre Girma ◽  
Catherine Lacombe ◽  
Dominique Meyer ◽  
...  
Keyword(s):  
Shear Stress ◽  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Inhibitory Effect ◽  
Platelet Glycoprotein ◽  
Rotational Viscometer ◽  
Induce Platelet Aggregation ◽  
Static Conditions ◽  
Von Willebrand ◽  
Willebrand Factor

AbstractShear-induced platelet aggregation (SIPA) involves von Willebrand Factor (vWF) binding to platelet glycoprotein (GP)Ib at high shear stress, followed by the activation of αIIbβ3. The purpose of this study was to determine the vWF sequences involved in SIPA by using monoclonal antibodies (MoAbs) to vWF known to interfere with its binding to GPIb and to αIIbβ3. Washed platelets were exposed to shear rates between 100 and 4,000 seconds−1 in a rotational viscometer. SIPA was quantitated by flow cytometry as the disappearance of single platelets (DSP) in the sheared sample in the presence of vWF, relative to a control in the absence of shear and vWF. At a shear rate of 4,000 seconds−1, DSP was increased from 5.9% ± 3.5% in the absence of vWF to 32.7% ± 6.3% in the presence of vWF. This increase in SIPA was not associated with an elevation of P-selectin expression. vWF-dependent SIPA was completely abolished by MoAb 6D1 to GPIb and partially inhibited by MoAb 10E5 to αIIbβ3. Three MoAbs to vWF were compared for their effect on SIPA at 4,000 seconds−1 in the presence of vWF: MoAb 328, known to block vWF binding to GPIb in the presence of ristocetin, MoAb 724 blocking vWF binding to GPIb in the presence of botrocetin, and MoAb 9, an inhibitor of vWF binding to αIIbβ3. Similar to the effect of MoAb 6D1, MoAb 328 completely inhibited the effect of vWF, whereas MoAb 9 had a partial inhibitory effect, as MoAb 10E5 did. In contrast, MoAb 724, as well as its F(ab′)2 fragments, promoted shear-dependent platelet aggregation (165% of the DSP value obtained in the absence of MoAb 724), indicating that MoAb 724 was responsible for an enhanced aggregation, which was independent of binding to the platelet Fcγ receptor. In addition, the enhancement of aggregation induced by MoAb 724 was abrogated by MoAb 6D1 or 10E5 to the level of SIPA obtained in the presence of vWF incubated with a control MoAb to vWF. Finally, the activating effect of MoAb 724 was also found under static conditions at ristocetin concentrations too low to induce platelet aggregation. Our results suggested that on binding to a botrocetin-binding site on vWF, MoAb 724 mimics the effect of botrocetin by inducing an active conformation of vWF that is more sensitive to shear stress or to low ristocetin concentration.

Generalized Models for Laminar Developing Flows in Heat Sinks and Heat Exchangers

2011 ◽  
Author(s):  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchangers ◽  
Heat Sinks ◽  
Length Scale ◽  
Square Root ◽  
Sectional Area ◽  
Cross Sectional

Recent models for laminar friction and heat transfer in non-circular ducts and channels are reviewed. Models for both hydrodynamically and thermally developing flows are presented. These models are based on the superposition of asymptotic characteristics for short and long ducts. The non-dimensional mean wall shear stress (or fRe) and non-dimensional heat transfer coefficient (or Nusselt number) are shown to be only functions the dimensionless hydrodynamic or thermal duct length, respectively, and the duct aspect ratio. This is achieved by means of using a new transversal length scale, the square root of cross-sectional area, rather than the hydraulic diameter. Additional definitions more appropriate to single fluid devices such as heat sinks are also discussed.

The Influence of Base Oil and Thixotropy on Magnetorheological Property of MRF

2013 ◽  
Vol 320 ◽  
pp. 19-24
Author(s):  
Jian Jian Yang ◽  
Hua Yan ◽  
Zhi De Hu ◽  
Shi Xiang Xu
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Magnetorheological Fluid ◽  
Mineral Oil ◽  
Dispersed Phase ◽  
Zero Field ◽  
Rotational Viscometer ◽  
Base Oil ◽  
Low Shear

Adopting carbonyl iron powder and silicone/mineral oil as suspend phase and dispersed phase separately,and silica, kaolin as lubricant additives,magnetorheological (MR) fluid was prepared by ball milling. The apparent viscosity of base oil and shear stress were measured on a modified rotational viscometer. The experimental results demonstrated that an appropriate viscosity of base oil contributed to the rheology of MRF. Adding a small amount of thixotropy into MRF had little influence on zero-field viscosity, which facilitated the application of MRF to maintain adequate liquidity. Under low shear rate conditions, the shear stress was improved by adding thixotropy to some extent, especially in the mineral oil-based magnetorheological fluid, in which the role of silica was superior to kaolin.

Effect of temperature and concentration on density and rheological properties of melon (Cucumis melo L. var. Inodorus) juice

2014 ◽  
Vol 44 (2) ◽  
pp. 168-178 ◽  
Author(s):  
Ali Mohamadi Sani ◽  
Ghazaleh Hedayati ◽  
Akram Arianfar
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Apparent Viscosity ◽  
Flow Behavior ◽  
Effect Of Temperature ◽  
Plastic Behavior ◽  
Linear Quadratic ◽  
Concentric Cylinder ◽  
Rotational Viscometer ◽  
Content Type

Purpose – The aim of this study was to measure the apparent viscosity, flow behavior and density of melon juice as a function of temperature and juice concentration and to obtain simple equations to correlate experimental data. Design/methodology/approach – Melon juice was concentrated in a rotary evaporator to 40±1, 52.5±1 and 65±1°Brix at 50°C, 80 rpm and stored at 4°C until analysis. Density of melon juice was determined with 25 ml pycnometer at 15, 25 and 35°C and was expressed as kg/m3. All experiments were conducted in triplicate. Experimental data were fitted to different models (linear, quadratic, exponential, quadratic exponential and polynomial) using Minitab 16. Significant differences in the mean values were reported at p<0.05. The flow behavior of melon juice was determined using a concentric cylinder rotational viscometer at shear rate range of 13.2-330 s−1 and temperatures of 15, 25 and 35°C. The experimental data were analyzed Slide Write V7.01 Trial Size (p<0.05) and the rheograms was plotted by Microsoft Excel 2007. Findings – Results showed that the four-term polynomial model is the best model for computing density values from temperature and concentration (R2=0.999). The measured shear stress was within 1.69-780 Pa, corresponding to viscosity range of 0.016-0.237 Pa · s. Within the tested conditions, the concentrate exhibited a pseudo plastic behavior. Temperature had an inverse effect on shear stress and apparent viscosity. Originality/value – No research had been done on production of melon juice concentrate.

Sign in / Sign up

Export Citation Format

Share Document