Vesicles in Poiseuille Flow

Danker, Gerrit; Vlahovska, Petia M.; Misbah, Chaouqi

doi:10.1103/physrevlett.102.148102

Cited by 117 publications

(119 citation statements)

References 26 publications

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“…The strain rate is given as _ c ¼ 2y 0 a where y 0 is the distance between the center of the polymer and the flow axis and a is a measure of the curvature of the flow profile. 22 Simple shear flow on the other hand describes fluid flow characterized by a velocity gradient perpendicular to the flow field ( Figure 1). It is modeled as a linear superposition of rotational flow with vorticity x, and elongational flow with strain rate _ c ¼ @v x @y .…”

Section: Studying the Effect Of Shear Flow On Proteinsmentioning

confidence: 99%

The effects of shear flow on protein structure and function

Bekard

Asimakis

Bertolini³

et al. 2011

Biopolymers

181

140

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Toxoplasma gondii usually causes an asymptomatic and then latent infection in human adults; however, a potentially fatal disseminated form can occur in immunocompromised patients. Given that the diagnosis of acute Toxoplasma infection, as opposed to latent disease, relies on finding direct evidence of T. gondii infection in tissue, pathologic examination is critical. There have only been a few reports describing the cytomorphology of Toxoplasma in exfoliative cytology, and no reports of the findings in Thin Prep. In this report, we describe a fatal case of toxoplasmosis in a cardiac transplant patient that was diagnosed by respiratory cytopathology. Although the extracellular organisms were well visualized on the Wright‐Giemsa stained cytospin, they were only faintly seen on the Pap‐stained cytospin trapped within mucin and were not easily appreciated on the ThinPrep slides nor the H&E stained cell block sections. An immunohistochemical stain for Toxoplasma performed on the cell block was strongly positive, and an autopsy performed on the patient confirmed disseminated infection. Our case illustrates that the diagnosis of Toxoplasma in exfoliative cytology specimens can be challenging since organisms are not well visualized on ThinPrep or Pap‐stained material; therefore, Wright‐Giemsa stained material can be particularly helpful. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.

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Section: Studying the Effect Of Shear Flow On Proteinsmentioning

confidence: 99%

The effects of shear flow on protein structure and function

Bekard

Asimakis

Bertolini³

et al. 2011

Biopolymers

181

140

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“…In these models, it is presumed that the lift force always acts in the opposite direction of the wall to push the particle towards the centerline. Indeed, analytical 126 and numerical 127 studies have shown that vesicles, unlike surfactant-free drops, always migrate towards the central axis in Poiseuille flow, regardless of the value of the viscosity ratio. Exploiting deformability-induced particle migration opens new ways to focus and separate cells based on their inherent structural characteristics which results in passive, label-free cell sorting processes in microfluidics.…”

Section: Deformability-selective Cell Separationmentioning

confidence: 99%

Hydrodynamic mechanisms of cell and particle trapping in microfluidics

2013

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Focusing and sorting cells and particles utilizing microfluidic phenomena have been flourishing areas of development in recent years. These processes are largely beneficial in biomedical applications and fundamental studies of cell biology as they provide cost-effective and point-of-care miniaturized diagnostic devices and rare cell enrichment techniques. Due to inherent problems of isolation methods based on the biomarkers and antigens, separation approaches exploiting physical characteristics of cells of interest, such as size, deformability, and electric and magnetic properties, have gained currency in many medical assays. Here, we present an overview of the cell/particle sorting techniques by harnessing intrinsic hydrodynamic effects in microchannels. Our emphasis is on the underlying fluid dynamical mechanisms causing cross stream migration of objects in shear and vortical flows. We also highlight the advantages and drawbacks of each method in terms of throughput, separation efficiency, and cell viability. Finally, we discuss the future research areas for extending the scope of hydrodynamic mechanisms and exploring new physical directions for microfluidic applications.

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“…We believe that when studying the motion through narrow constrictions resistance to shear should be taken into account given the large viscous shear stresses that induce large deformations. Nevertheless there is a wealth of numerical studies on the motion of vesicles in shear flows which led to the observation of discocytes and slippers shapes in a Poiseuille flow [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Motion of an elastic capsule in a constricted microchannel

et al. 2015

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We study the motion of an elastic capsule through a microchannel characterized by a localized constriction. We consider a capsule with a stress-free spherical shape and impose its steady state configuration in an infinitely long straight channel as the initial condition for our calculations. We report how the capsule deformation, velocity, retention time, and maximum stress of the membrane are affected by the capillary number, Ca, and the constriction shape. We estimate the deformation by measuring the variation of the three-dimensional surface area and a series of alternative quantities easier to extract from experiments. These are the Taylor parameter, the perimeter and the area of the capsule in the spanwise plane. We find that the perimeter is the quantity that reproduces the behavior of the three-dimensional surface area the best. This is maximum at the centre of the constriction and shows a second peak after it, whose location depends on the Ca number. We observe that, in general, area-deformation correlated quantities grow linearly with Ca, while velocity-correlated quantities saturate for large Ca but display a steeper increase for small Ca. The velocity of the capsule divided by the velocity of the flow displays, surprisingly, two different qualitative behaviors for small and large capillary numbers. Finally, we report that longer constrictions and spanwise wall bounded (versus spanwise periodic) domains cause larger deformations and velocities. If the deformation and velocity in the spanwise wall bounded domains are rescaled by the initial equilibrium deformation and velocity, their behavior is undistinguishable from that in a periodic domain. In contrast, a remarkably different behavior is reported in sinusoidally shaped and smoothed rectangular constrictions indicating that the capsule dynamics is particularly sensitive to abrupt changes in the cross section. In a smoothed rectangular constriction larger deformations and velocities occur over a larger distance.

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Vesicles in Poiseuille Flow

Cited by 117 publications

References 26 publications

The effects of shear flow on protein structure and function

The effects of shear flow on protein structure and function

Hydrodynamic mechanisms of cell and particle trapping in microfluidics

Motion of an elastic capsule in a constricted microchannel

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