Star Polymers in Shear Flow

Ripoll, Marisol; Winkler, Roland G.; Gompper, Gerhard

doi:10.1103/physrevlett.96.188302

Cited by 152 publications

(268 citation statements)

References 24 publications

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“…This technique uses a large number of coarse‐grained solvent particles to efficiently model the behavior of a fluid, including embedded structures and active swimmers. Transport behavior of MPCD was well characterized by this study and others,59, 60, 61, 62, 63, 64, 65 and applied to a diverse set of problems 66, 67, 68, 69. including sperm motility and cooperation 46, 70, 71.…”

Section: Methodsmentioning

confidence: 59%

Guidance and Self‐Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest

et al. 2017

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Male infertility is a reproductive disease, and existing clinical solutions for this condition often involve long and cumbersome sperm sorting methods, including preprocessing and centrifugation‐based steps. These methods also fall short when sorting for sperm free of reactive oxygen species, DNA damage, and epigenetic aberrations. Although several microfluidic platforms exist, they suffer from structural complexities, i.e., pumps or chemoattractants, setting insurmountable barriers to clinical adoption. Inspired by the natural filter‐like capabilities of the female reproductive tract for sperm selection, a model‐driven design, featuring pillar arrays that efficiently and noninvasively isolate highly motile and morphologically normal sperm, with lower epigenetic global methylation, from raw semen, is presented. The Simple Periodic ARray for Trapping And isolatioN (SPARTAN) created here modulates the directional persistence of sperm, increasing the spatial separation between progressive and nonprogressive motile sperm populations within an unprecedentedly short 10 min assay time. With over 99% motility of sorted sperm, a 5‐fold improvement in morphology, 3‐fold increase in nuclear maturity, and 2–4‐fold enhancement in DNA integrity, SPARTAN offers to standardize sperm selection while eliminating operator‐to‐operator variations, centrifugation, and flow. SPARTAN can also be applied in other areas, including conservation ecology, breeding of farm animals, and design of flagellar microrobots for diagnostics.

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Section: Methodsmentioning

confidence: 59%

Guidance and Self‐Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest

et al. 2017

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“…Furthermore, we have ignored the deformability of the stars under shear flow. Indeed, there is evidence that a single star will deform, albeit slightly, under strong shear (Ripoll et al 2006). Our promising results will trigger further improvements in the future, including incorporation of deformability.…”

Section: Discussionmentioning

confidence: 99%

Computer simulation of the rheology of concentrated star polymer suspensions

et al. 2009

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We use particle-based computer simulations to study the rheology of suspensions of highfunctionality star polymers with long entangled arms. Such particles have properties which are intermediate between those of soft colloidal particles and entangled polymer chains. In the simulations, each star polymer is coarse-grained to a single particle. In order to faithfully reproduce dynamical properties, it is very important to not only include time-averaged interactions (potentials of mean force) but to also account for transient interactions induced by entanglements between the arms of different star polymers. Using a model which has all these features, it is found that, for sufficiently high shear rates, the start-up shear stress displays an overshoot. With increasing concentration, the core interactions increasingly dominate the initial stress response, leading to a maximum in the stress overshoot at relatively low strain values (0.1 to 0.5). Transient forces start to dominate after this initial stage. In a simulated experi- ment in which the shear rate is suddenly stepped-down from a high to a lower value, the stress shows a clear undershoot, with the minimum stress again at a relatively low strain value (based on the new shear rate). Finally, it is shown that a stress plateau develops in the flow curve. This plateau is absent when the transient forces between the polymer stars are not taken into account.

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“…For large Weissenberg numbers, this leads to very large fluctuations of the largest intramolecular distance of a linear polymer with time, as demonstrated experimentally in Refs. [146,150], and reproduced in the MPC simulations [142], see Fig. 18.…”

Section: Ultra-soft Colloids In Shear Flowmentioning

confidence: 99%

“…Data for different L f collapse onto universal curves, which approach a plateau for small shear rates, as expected. For larger shear rates, Wi 1, a power-law behavior [142] …”

Section: Ultra-soft Colloids In Shear Flowmentioning

confidence: 99%

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Multi-Particle Collision Dynamics: A Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids

Gompper

Ihle

Kroll

et al.

Advanced Computer Simulation Approaches for Soft Matter Sciences III

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362

588

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In this review, we describe and analyze a mesoscale simulation method for fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now called multi-particle collision dynamics (MPC) or stochastic rotation dynamics (SRD). The method consists of alternating streaming and collision steps in an ensemble of point particles. The multi-particle collisions are performed by grouping particles in collision cells, and mass, momentum, and energy are locally conserved. This simulation technique captures both full hydrodynamic interactions and thermal fluctuations. The first part of the review begins with a description of several widely used MPC algorithms and then discusses important features of the original SRD algorithm and frequently used variations. Two complementary approaches for deriving the hydrodynamic equations and evaluating the transport coefficients are reviewed. It is then shown how MPC algorithms can be generalized to model non-ideal fluids, and binary mixtures with a consolute point. The importance of angular-momentum conservation for systems like phase-separated liquids with different viscosities is discussed. The second part of the review describes a number of recent applications of MPC algorithms to study colloid and polymer dynamics, the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of viscoelastic fluids.

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Star Polymers in Shear Flow

Cited by 152 publications

References 24 publications

Guidance and Self‐Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest

Guidance and Self‐Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest

Computer simulation of the rheology of concentrated star polymer suspensions

Multi-Particle Collision Dynamics: A Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids

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