The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Elizabeth M. Van Cott - One of the best experts on this subject based on the ideXlab platform.
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Assessment of a Cohort of Primarily Pediatric Patients with a Presumptive Diagnosis of Type 1 von Willebrand Disease with a Novel High Shear Rate, Non-citRated Blood Flow Device
Thrombosis research, 2012Co-Authors: Eric F. Grabowski, Marjorie A. Curran, Elizabeth M. Van CottAbstract:Abstract Background A precise approach to the diagnosis of von Willebrand disease (vWD) remains elusive. One important reason is that vWD is a blood flow‐related disorder: a vW Factor‐platelet GPIb binding defect exists in this condition under the High Shear‐Rate (> 1000 sec‐1 in whole blood; > 3000 sec‐1 in PRP) conditions of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs. Methods We therefore studied 28 patients (mean 18.9 yrs) with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 26 healthy controls (mean 17.5 yrs). Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75 μg/ml of the Tab (anti‐CD41) monoclonal antibody directed against platelet GPIIb, and 1.0 μg/ml of an ALEXA 555‐conjugated rabbit anti‐mouse second antibody. Within 30–90 min, the blood was then withdrawn at 667 and 1330 sec− 1 through a special flow chamber allowing for real-time epifluorescence digital videomicroscopy of platelets interacting with a microfibrillar collagen substRate. With MetaMorph software (Universal Imaging) we quantified the percent area (PA) covered by and total volume (TV) of adherent platelet aggregates within a 435 μm × 580 μm field of view. Results At 667 sec− 1 after 1 min PA and TV were similar for patients and controls, but at 1330 sec− 1 PA was 9.32 ± 4.21 (mean ± SD) for patients, a value lower (p Conclusions The novel flow device found that PA and TV were significantly reduced under High Shear stress in vWD patients compared to normal controls. However, there was some overlap between the vWD and the control group, suggesting that some vWD patients had normal platelet adhesion/aggregation under the conditions studied. Further study with a Higher Shear Rate appears indicated.
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reduced volume and pattern of platelet aggregation imaged using epifluorescence digital videomicroscopy in a High Shear Rate blood flow chamber permit the sensitive and specific diagnosis of von willebrand disease
Blood, 2009Co-Authors: Eric F. Grabowski, Ming Cheung, Emily E Biliouris, Rafail I Kushak, Elizabeth M. Van CottAbstract:Abstract 3051 Poster Board II-1027 Von Willebrand disease (vWD) is one of the most common bleeding disorders worldwide, yet a precise approach to the diagnosis of this condition and prediction of its severity remains elusive. One important reason is that vWD is a blood flow-related disorder: a vW Factor-platelet GPIb binding defect in this condition exists under the High Shear-Rate conditions (>670 sec-1 in whole blood; >2000 sec-1 in PRP) of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs. We therefore studied 15 children (ages 2-17, mean 9.9 yrs) and 2 adults with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 12 healthy pediatric and adult controls. Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75 μg/ml of the Tab (anti-CD41) monoclonal antibody directed against platelet GPIIb (courtesy of R. P. McEver), 1.0 μg/ml of an ALEXA 555-conjugated rabbit anti-mouse second antibody, and PBS (9 parts blood:1 part PBS). Within 30-90 min, the blood was then withdrawn at 667 and 1330 sec-1 through a special flow chamber allowing for blood exposure to 150 μm glass cover clips precoated with microfibrillar collagen (Helena Laboratories). Using epifluorescence digital videomicroscopy, we imaged platelets interacting in real time with the collagen substRate, and quantified with Simple PCI software the percent area (PA) covered by adherent platelet aggregates, the number of platelet aggregates (NA), and the total volume (TV) of these aggregates within a 435 μm x 580 μm field of view. Resolution was better than 1 μm. Clinical bleeding score (ICTH) and ristocetin cofactor activity were also recorded. TV at 1330 sec-1 after 1 min, normalized to TV at 670 sec-1 after 1 min, to minimize patient/subject variation, was 2.65 ± 0.483 (mean ± SE) for normal subjects, but 1.55 ± 0.249 in vWD (P =0.043). The visualized pattern of platelet aggregation itself (Figs. 1 and 2, flow top-to-bottom) identified 14/16 patients, for whom aggregates were 19 μm in width or smaller but NA was 500-1000, and 6/7 controls, for whom aggregates were 32 μm in width or larger and NA was 300-600. This pattern is in accord with a greater accessibility of fresh platelets for the collagen surface in the presence of smaller aggregates, which “shield” neighboring surface sites less than do larger aggregates. Normalized TV, ristocetin cofactor activity, and bleeding score were not strongly correlated with one another, although bleeding score was positively correlated with age (P =0.0097). Platelet aggregate volume in vWD is markedly reduced in whole blood at a Shear Rate of 1330 sec-1, with a pattern of smaller but more numerous aggregates providing a High degree of sensitivity and specificity in the diagnosis of vWD. ![Figure][1] Disclosures No relevant conflicts of interest to declare. [1]: pending:yes
Patrice Estelle - One of the best experts on this subject based on the ideXlab platform.
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Stability and viscosity of CuO water nanofluids at very High Shear Rate
Journal of Nanofluids, 2017Co-Authors: Patrice Estelle, Thierry Mare, Frédéric Fraïsse, Aymeric Audfray, Cong Tam NguyenAbstract:We report the viscosity measurement of water-based nanofluids containing CuO spherical nanoparticles of about 29 nm in diameter. Using an innovative experimental procedure and a microfluidic “Viscometer Rheometer On a Chip”, (mVROCTM) viscosity data were collected for several nanoparticle volume fractions and a Shear Rate ranging up to 20,000s-1. The effect of low nanoparticle volume fraction and temperature on nanofluids viscosity was considered and discussed in this work. The stability and dispersion state of nanofluids were also studied from rheological measurements and nanoparticle tracking analysis. The possible effects due to the temperature hysteresis behavior of aggregated nanofluids under cooling and heating cycle is reported as well.
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viscosity of carbon nanotubes water based nanofluids influence of concentration and temperature
International Journal of Thermal Sciences, 2013Co-Authors: Salma Halelfadl, Patrice Estelle, Bahadir Aladag, Nimeti Doner, Thierry MareAbstract:Abstract Experimental results on the steady-state viscosity of carbon nanotubes water-based nanofluids are presented considering the influence of particle volume fraction and temperature ranging from 0 to 40 °C. The suspensions consist of multi-walled carbon nanotubes dispersed in de-ionized water and they are stabilized by a surfactant. The aspect ratio of nanotubes is close to 160 and the particle volume fraction varies between 0.0055% and 0.55%. It is shown that the nanofluids behave as Shear-thinning materials for High particle content. For lower particle content, the nanofluids are quite Newtonian. It is also observed that the relative viscosity of nanofluids at High Shear Rate does not vary with temperature. Moreover, the evolution of relative viscosity at High Shear Rate is well predicted by the Maron–Pierce model considering the effect of nanoparticles agglomeRates.
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Experimental investigations of the viscosity of nanofluids at low temperatures
Applied Energy, 2012Co-Authors: Bahadir Aladag, Salma Halelfadl, Nimeti Doner, Thierry Mare, Steven Duret, Patrice EstelleAbstract:The effects due to temperature and Shearing time on viscosity for Al 2 O 3 /water and CNT/water based nanofluids at low concentration and low temperatures are experimentally investigated. The viscosity data were collected using a stress-controlled rheometer equipped with parallel plate geometry under up and down Shear stress ramp. CNT and Al 2 O 3 water based nanofluids exhibited hysteresis behaviour when the stress is gradually loaded and unloaded, depending also on Shearing time. Experiments also showed that the nanofluid suspensions indicated either Newtonian or non-Newtonian behaviour, depending on Shear Rate. CNT water based nanofluid behaves as Newtonian fluid at High Shear Rate whereas Al 2 O 3 water based nanofluid is non-Newtonian within the range of low temperatures investigated.
Sandra Lerouge - One of the best experts on this subject based on the ideXlab platform.
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Elastic Turbulence in Shear Banding Wormlike Micelles
Physical Review Letters, 2010Co-Authors: Marc-antoine Fardin, Diego Lopez, Julien Crozo, Guillaume Grégoire, Olivier Cardoso, G.h. Mckinley, Sandra LerougeAbstract:We study the dynamics of the Taylor-Couette flow of Shear banding wormlike micelles. We focus on the High Shear Rate branch of the flow curve and show that for sufficiently High Weissenberg numbers, this branch becomes unstable. This instability is strongly subcritical and is associated with a Shear stress jump. We find that this increase of the flow resistance is related to the nucleation of turbulence. The flow pattern shows similarities with the elastic turbulence, so far only observed for polymer solutions. The unstable character of this branch led us to propose a scenario that could account for the recent observations of Taylor-like vortices during the Shear banding flow of wormlike micelles.
Thierry Mare - One of the best experts on this subject based on the ideXlab platform.
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Stability and viscosity of CuO water nanofluids at very High Shear Rate
Journal of Nanofluids, 2017Co-Authors: Patrice Estelle, Thierry Mare, Frédéric Fraïsse, Aymeric Audfray, Cong Tam NguyenAbstract:We report the viscosity measurement of water-based nanofluids containing CuO spherical nanoparticles of about 29 nm in diameter. Using an innovative experimental procedure and a microfluidic “Viscometer Rheometer On a Chip”, (mVROCTM) viscosity data were collected for several nanoparticle volume fractions and a Shear Rate ranging up to 20,000s-1. The effect of low nanoparticle volume fraction and temperature on nanofluids viscosity was considered and discussed in this work. The stability and dispersion state of nanofluids were also studied from rheological measurements and nanoparticle tracking analysis. The possible effects due to the temperature hysteresis behavior of aggregated nanofluids under cooling and heating cycle is reported as well.
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viscosity of carbon nanotubes water based nanofluids influence of concentration and temperature
International Journal of Thermal Sciences, 2013Co-Authors: Salma Halelfadl, Patrice Estelle, Bahadir Aladag, Nimeti Doner, Thierry MareAbstract:Abstract Experimental results on the steady-state viscosity of carbon nanotubes water-based nanofluids are presented considering the influence of particle volume fraction and temperature ranging from 0 to 40 °C. The suspensions consist of multi-walled carbon nanotubes dispersed in de-ionized water and they are stabilized by a surfactant. The aspect ratio of nanotubes is close to 160 and the particle volume fraction varies between 0.0055% and 0.55%. It is shown that the nanofluids behave as Shear-thinning materials for High particle content. For lower particle content, the nanofluids are quite Newtonian. It is also observed that the relative viscosity of nanofluids at High Shear Rate does not vary with temperature. Moreover, the evolution of relative viscosity at High Shear Rate is well predicted by the Maron–Pierce model considering the effect of nanoparticles agglomeRates.
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Experimental investigations of the viscosity of nanofluids at low temperatures
Applied Energy, 2012Co-Authors: Bahadir Aladag, Salma Halelfadl, Nimeti Doner, Thierry Mare, Steven Duret, Patrice EstelleAbstract:The effects due to temperature and Shearing time on viscosity for Al 2 O 3 /water and CNT/water based nanofluids at low concentration and low temperatures are experimentally investigated. The viscosity data were collected using a stress-controlled rheometer equipped with parallel plate geometry under up and down Shear stress ramp. CNT and Al 2 O 3 water based nanofluids exhibited hysteresis behaviour when the stress is gradually loaded and unloaded, depending also on Shearing time. Experiments also showed that the nanofluid suspensions indicated either Newtonian or non-Newtonian behaviour, depending on Shear Rate. CNT water based nanofluid behaves as Newtonian fluid at High Shear Rate whereas Al 2 O 3 water based nanofluid is non-Newtonian within the range of low temperatures investigated.
G.h. Mckinley - One of the best experts on this subject based on the ideXlab platform.
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Elastic Turbulence in Shear Banding Wormlike Micelles
Physical Review Letters, 2010Co-Authors: Marc-antoine Fardin, Diego Lopez, Julien Crozo, Guillaume Grégoire, Olivier Cardoso, G.h. Mckinley, Sandra LerougeAbstract:We study the dynamics of the Taylor-Couette flow of Shear banding wormlike micelles. We focus on the High Shear Rate branch of the flow curve and show that for sufficiently High Weissenberg numbers, this branch becomes unstable. This instability is strongly subcritical and is associated with a Shear stress jump. We find that this increase of the flow resistance is related to the nucleation of turbulence. The flow pattern shows similarities with the elastic turbulence, so far only observed for polymer solutions. The unstable character of this branch led us to propose a scenario that could account for the recent observations of Taylor-like vortices during the Shear banding flow of wormlike micelles.