The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Patrick S. Doyle - One of the best experts on this subject based on the ideXlab platform.
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Revisiting the Conformation and Dynamics of DNA in Slitlike Confinement
Macromolecules, 2010Co-Authors: Jing Tang, Stephen L. Levy, Daniel W. Trahan, Jeremy J. Jones, Harold G. Craighead, Patrick S. DoyleAbstract:We experimentally investigated the equilibrium conformation and dynamics of single DNA molecules in slitlike nanochannels. We measured the in-plane radius of gyration (R ) diffusivity (D), and Longest Relaxation Time (τ)ofλ-DNA (48.5 kbp) as functions of the slit height using fluorescence microscopy. Our results show that the in-plane radius of gyration increases monotonically with decreasing slit height, in contrast to results from Bonthuis et al. 15 but in agreement with our simulations and those of other groups. In strongconfinement (slit height
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Electrophoretic Stretching of DNA Molecules in Cross-Slot Nanoslit Channels
Macromolecules, 2008Co-Authors: Anthony Balducci, Jing Tang, Patrick S. DoyleAbstract:A nanofluidic cross-slot device is designed and fabricated to investigate the effects of slitlike confinement on the electrophoretic stretching of single DNA molecules. The device is capable of trapping and stretching single DNA molecules at the stagnation point of a homogeneous planar elongational electric field. Different from studies of unconfined DNA, the Longest Relaxation Time in slitlike confinement is extension-dependent, and we find the higher extension Relaxation Time allows better prediction of the drastic increase of extension with applied strain rate in confinement. The low extension Relaxation Time is important in polymer rotation and small deviations from equilibrium.
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Ionic effects on the equilibrium dynamics of DNA confined in nanoslits.
Nano letters, 2008Co-Authors: Chih-chen Hsieh, Anthony Balducci, Patrick S. DoyleAbstract:The ionic effects on the dynamics and conformation of DNA in silt-like confinement are investigated. Confined λ-DNA is considered as a model polyelectrolyte, and its Longest Relaxation Time, diffusivity, and size are measured at a physiological ionic strength between 1.7−170 mM. DNA properties change drastically in response to the varying ionic environment, and these changes can be explained by blob theory with an electrostatically mediated effective diameter and persistence length. In the ionic range we investigate, the effective diameter of DNA that represents the electrostatic repulsion between remote segments is found to be the main driving force for the observed change in DNA properties. Our results are useful for understanding the manipulation of biomolecules in nanofluidic devices.
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Relaxation of stretched DNA in slitlike confinement.
Physical review letters, 2007Co-Authors: Anthony Balducci, Chih-chen Hsieh, Patrick S. DoyleAbstract:We experimentally observe two separate Time scales governing the entropic recoil in the linear force-extension regime of single double-stranded DNA in slit confinement. We demonstrate the existence of two distinct Relaxation regimes at different extensions during Relaxation. Contrary to bulk measurements, the true Longest Relaxation Time may only be probed very close to equilibrium. A simple model of the Relaxation mechanism leads to a scaling analysis that correctly predicts the extension at the crossover between the two regimes.
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Accuracy of bead-spring chains in strong flows
Journal of Non-newtonian Fluid Mechanics, 2007Co-Authors: Patrick T. Underhill, Patrick S. DoyleAbstract:We have analyzed the response of bead-spring chain models in strong elongational flow as the amount of polymer represented by a spring is changed. We examined the Longest Relaxation Time of the chains which is used to quantify the strength of the flow in terms of a Weissenberg number. A chain with linear springs can be used to predict the Longest Relaxation Time of the nonlinear chains if the linear spring constant is modified correctly. We used the expansion of the elongational viscosity in the limit of infinite Weissenberg number to investigate the change of the viscosity as the scale of discretization was changed. We showed that the viscosity is less sensitive to the details of the spring force law because the chain is fully extended at very large Weissenberg number. However, the approach to that infinite Weissenberg number response is dependent both on the behavior of the spring force at large force and the behavior at small force. New spring force laws to represent the worm-like chain or the freely jointed chain are correct at both of these limits, while other currently used force laws produce and error. We also investigated the applicability of these expansions to chains including hydrodynamic interactions. Our results suggest that the Longest Relaxation Time may not be the appropriate Time scale needed to non-dimensionalize the strain rate in such highly extended states.
Frédéric Restagno - One of the best experts on this subject based on the ideXlab platform.
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Viscoelasticity induced onset of slip at the wall for polymer fluids
ACS Macro Letters, 2020Co-Authors: Marion Grzelka, Iurii Antoniuk, Eric Drockenmuller, Alexis Chennevière, Liliane Léger, Frédéric RestagnoAbstract:The progressive onset of slip at the wall, which corresponds to a slip length increasing with the solicitation Time before reaching a plateau, has been investigated for model viscoelastic polymer solutions, allowing one to vary the Longest Relaxation Time while keeping constant solid - fluid interactions. A hydrodynamic model based on a Maxwell fluid and the classical Navier's hypothesis of a linear response for the friction stress at the interface fully accounts for the data, without any adjustable parameter. No viscoelastic response needs be postulated for the friction, reflecting the local character of solid-liquid friction mechanisms.
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Viscoelasticity-Induced Onset of Slip at the Wall for Polymer Fluids
ACS Macro Letters, 2020Co-Authors: Marion Grzelka, Iurii Antoniuk, Eric Drockenmuller, Alexis Chennevière, Liliane Léger, Frédéric RestagnoAbstract:The progressive onset of slip at the wall, which corresponds to a slip length increasing with the solicitation Time before reaching a plateau, has been investigated for model viscoelastic polymer solutions, allowing one to vary the Longest Relaxation Time while keeping constant solid-fluid interactions. A hydrodynamic model based on a Maxwell fluid and the classical Navier's hypothesis of a linear response for the friction stress at the interface fully accounts for the data. In the limit of the linear viscoelasticity of the fluid, we could postulate a Newtonian response for the interfacial friction coefficient reflecting the local character of solid-liquid friction mechanisms. Deviations between the experiments and our model are observed when the fluid is far from its linear viscoelastic behavior.
Marion Grzelka - One of the best experts on this subject based on the ideXlab platform.
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Viscoelasticity induced onset of slip at the wall for polymer fluids
ACS Macro Letters, 2020Co-Authors: Marion Grzelka, Iurii Antoniuk, Eric Drockenmuller, Alexis Chennevière, Liliane Léger, Frédéric RestagnoAbstract:The progressive onset of slip at the wall, which corresponds to a slip length increasing with the solicitation Time before reaching a plateau, has been investigated for model viscoelastic polymer solutions, allowing one to vary the Longest Relaxation Time while keeping constant solid - fluid interactions. A hydrodynamic model based on a Maxwell fluid and the classical Navier's hypothesis of a linear response for the friction stress at the interface fully accounts for the data, without any adjustable parameter. No viscoelastic response needs be postulated for the friction, reflecting the local character of solid-liquid friction mechanisms.
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Viscoelasticity-Induced Onset of Slip at the Wall for Polymer Fluids
ACS Macro Letters, 2020Co-Authors: Marion Grzelka, Iurii Antoniuk, Eric Drockenmuller, Alexis Chennevière, Liliane Léger, Frédéric RestagnoAbstract:The progressive onset of slip at the wall, which corresponds to a slip length increasing with the solicitation Time before reaching a plateau, has been investigated for model viscoelastic polymer solutions, allowing one to vary the Longest Relaxation Time while keeping constant solid-fluid interactions. A hydrodynamic model based on a Maxwell fluid and the classical Navier's hypothesis of a linear response for the friction stress at the interface fully accounts for the data. In the limit of the linear viscoelasticity of the fluid, we could postulate a Newtonian response for the interfacial friction coefficient reflecting the local character of solid-liquid friction mechanisms. Deviations between the experiments and our model are observed when the fluid is far from its linear viscoelastic behavior.
Yogesh M. Joshi - One of the best experts on this subject based on the ideXlab platform.
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On the universality of the scaling relations during sol-gel transition
Journal of Rheology, 2020Co-Authors: Khushboo Suman, Yogesh M. JoshiAbstract:The evolution of viscoelastic properties near the sol-gel transition is studied by performing oscillatory rheological measurements on two different types of systems: a colloidal dispersion and a thermoresponsive polymer solution under isothermal and non-isothermal conditions. While undergoing sol-gel transition, both the systems pass through a critical point. An approach to the critical point is characterized in terms of divergence of zero-shear viscosity and the subsequent appearance of the low-frequency modulus. In the vicinity of the critical gel state, both the viscosity and the modulus show a power-law dependence on the relative distance from the critical point. Interestingly, the Longest Relaxation Time has been observed to diverge symmetrically on both sides of the critical point and also shows a power-law dependence on relative distance from the critical gel point. The critical (power-law) exponents of the zero-shear viscosity and modulus are observed to be related to the exponents of the Longest Relaxation Time by the hyperscaling laws. The dynamic critical exponent has also been calculated from the growth of the dynamic moduli. Remarkably, the critical Relaxation exponent and dynamic critical exponent predicted from the scaling laws precisely agree with the experimental values from the isothermal as well as non-isothermal experiments. The associated critical exponents show remarkable internal consistency and advocate the universality of scaling relations for different kinds of systems undergoing the sol-gel transition.
Anthony Balducci - One of the best experts on this subject based on the ideXlab platform.
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Electrophoretic Stretching of DNA Molecules in Cross-Slot Nanoslit Channels
Macromolecules, 2008Co-Authors: Anthony Balducci, Jing Tang, Patrick S. DoyleAbstract:A nanofluidic cross-slot device is designed and fabricated to investigate the effects of slitlike confinement on the electrophoretic stretching of single DNA molecules. The device is capable of trapping and stretching single DNA molecules at the stagnation point of a homogeneous planar elongational electric field. Different from studies of unconfined DNA, the Longest Relaxation Time in slitlike confinement is extension-dependent, and we find the higher extension Relaxation Time allows better prediction of the drastic increase of extension with applied strain rate in confinement. The low extension Relaxation Time is important in polymer rotation and small deviations from equilibrium.
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Ionic effects on the equilibrium dynamics of DNA confined in nanoslits.
Nano letters, 2008Co-Authors: Chih-chen Hsieh, Anthony Balducci, Patrick S. DoyleAbstract:The ionic effects on the dynamics and conformation of DNA in silt-like confinement are investigated. Confined λ-DNA is considered as a model polyelectrolyte, and its Longest Relaxation Time, diffusivity, and size are measured at a physiological ionic strength between 1.7−170 mM. DNA properties change drastically in response to the varying ionic environment, and these changes can be explained by blob theory with an electrostatically mediated effective diameter and persistence length. In the ionic range we investigate, the effective diameter of DNA that represents the electrostatic repulsion between remote segments is found to be the main driving force for the observed change in DNA properties. Our results are useful for understanding the manipulation of biomolecules in nanofluidic devices.
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Relaxation of stretched DNA in slitlike confinement.
Physical review letters, 2007Co-Authors: Anthony Balducci, Chih-chen Hsieh, Patrick S. DoyleAbstract:We experimentally observe two separate Time scales governing the entropic recoil in the linear force-extension regime of single double-stranded DNA in slit confinement. We demonstrate the existence of two distinct Relaxation regimes at different extensions during Relaxation. Contrary to bulk measurements, the true Longest Relaxation Time may only be probed very close to equilibrium. A simple model of the Relaxation mechanism leads to a scaling analysis that correctly predicts the extension at the crossover between the two regimes.
