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301. Conflicting effects of exercise on the establishment of a short-photoperiod phenotype in Syrian hamster

Author

Paul Pévet, Patrick Vuillez, Aurore Senser, Jerome S. Menet, Daniel Bonn, Challet, Etienne, Institut des Neurosciences Cellulaires et Intégratives (INCI), and Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Male, medicine.medical_specialty, endocrine system, Physiology, Photoperiod, Circadian clock, Hamster, Biology, Motor Activity, Physiology (medical), Internal medicine, Cricetinae, Testis, medicine, Animals, Circadian rhythm, [SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], photoperiodism, Epididymis, Mesocricetus, Suprachiasmatic nucleus, Seminal Vesicles, Feeding Behavior, Organ Size, biology.organism_classification, Adaptation, Physiological, Circadian Rhythm, Endocrinology, Phenotype, Light effects on circadian rhythm, Adipose Tissue, Hypothalamus, Suprachiasmatic Nucleus, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], sense organs, Proto-Oncogene Proteins c-fos, hormones, hormone substitutes, and hormone antagonists
Abstract

In the Syrian hamster, winter seasonal inhibition of reproduction occurs in response to decreasing day length. This inhibitory response is modulated by nonphotic cues. In particular, access to a running wheel has been shown to produce incomplete gonadal regression. The present study sought to determine whether this occurs as a consequence of wheel effect on adaptation of the circadian system to short days or whether downstream physiological responses are involved. Short-day adaptation of the circadian clock, which is located in the suprachiasmatic nucleus (SCN) of the hypothalamus, was tested by lengthening the photosensitive phase of the SCN (assayed by light-induced c-Fos expression in the SCN) as a parameter. We found that wheel-running activity does not inhibit the integration of the photoperiodic change by the SCN even if complete testicular regression is prevented. Moreover, this exercise was even capable of accelerating the lengthening of the photosensitive phase after the transfer to short day length. Thus, although wheel-running activity inhibits the short photoperiod-induced gonadal regression, it acts on the SCN to accelerate the integration of the photoperiodic change by the biological clock.

Published
2005

302. Spreading of non-Newtonian fluids and surfactant solutions on solid surfaces

Author

Daniel Bonn, Salima Rafaï, and Soft Matter (WZI, IoP, FNWI)

Subjects
Statistics and Probability, chemistry.chemical_classification, Materials science, Capillary action, Orders of magnitude (temperature), Thermodynamics, Polymer, Condensed Matter Physics, Non-Newtonian fluid, Pulmonary surfactant, chemistry, Rheology, Chemical physics, Newtonian fluid, Complex fluid
Abstract

The spreading of Newtonian fluids onto smooth solid substrates is well known; the speed of the contact line is given by a competition between capillary driving forces and viscous dissipation, yielding Tanner's law R∝t1/10R∝t1/10. Here, we study the spreading of droplets of complex fluids having either surfactants or polymers dissolved in the fluid. It turns out that both surfactants and polymers slow down the spreading. A special type of surfactants (trisiloxanes), however, leads to a “superspreading”, in which the droplet spreads out orders of magnitude quicker than with usual surfactants. The slowing down of the spreading can be explained quantitatively; however, the mechanism of the speeding up remains a puzzle.

Published
2005

303. Dislocation-mediated melting of a two-dimensional crystal

Author

Ludovic Pauchard, Jacques Meunier, and Daniel Bonn

Subjects
Stress (mechanics), Crystallography, Multidisciplinary, Congruent melting, Chemical physics, Chemistry, Free surface, Monolayer, Melting point, Slip melting point, Dislocation, Melting-point depression
Abstract

MELTING of three-dimensional solids usually starts at the free surface, which typically melts at a lower temperature than the bulk material1. In two dimensions the starting point of many studies is the Kosterlitz–Thouless theory2,3, in which melting is initiated through dislocation unbinding. Langmuir mono-layers—single layers of amphiphilic molecules formed at the air-water interface—should provide an ideal model for studying melting in two dimensions. Here we show that for monolayer crystals of fatty acids coexisting with their liquid phase, the interior melts before the edges. The melting of crystals under mechanical stress is initiated along the line at which the internal stress vanishes. We suggest that this apparently counterintuitive result arises from defect migration to the region of zero stress, where they accumulate and nucleate melting. These results support the idea that defects play a crucial role in melting of two-dimensional systems.

Published
1996

304. Rod-Climbing Effect in Newtonian Fluids

Author

Alexander Morozov, Daniel Bonn, Steffen Bohn, Mathias Kobylko, Wim van Saarloos, and Jacques Meunier

Subjects
chemistry.chemical_classification, Materials science, genetic structures, business.industry, General Physics and Astronomy, Mechanics, Polymer, Instability, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Optics, chemistry, Polymer solution, Climbing, Newtonian fluid, Meniscus, Liquid meniscus, sense organs, business, human activities, Polymer melt
Abstract

When a rotating rod is brought into a polymer melt or concentrated polymer solution, the meniscus climbs the rod. This spectacular rod climbing is due to the normal stresses present in the polymer fluid and is thus a purely non-Newtonian effect. A similar rod climbing of an interface between two fluids has therefore been taken as a signature that one of the fluids exhibits normal stress effects. We show here, however, that the effect can occur with simple Newtonian fluids: it occurs when a Taylor-Couette instability happens in the less viscous of the two liquids but not in the more viscous one.

Published
2004

305. Flow of wet granular materials

Author

Stéphane Rodts, Daniel Bonn, Nicolas Huang, Philippe Coussot, Guillaume Ovarlez, François Bertrand, and Soft Matter (WZI, IoP, FNWI)

Subjects
Materials science, Viscoplasticity, FOS: Physical sciences, General Physics and Astronomy, Thermodynamics, Mechanics, Condensed Matter - Soft Condensed Matter, Granular material, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Shear (sheet metal), Shear rate, Viscosity, Newtonian fluid, Soft Condensed Matter (cond-mat.soft), Shear flow, Couette flow
Abstract

The transition from frictional to lubricated flow of a dense suspension of non-Brownian particles is studied. The pertinent parameter characterizing this transition is the Leighton number $Le = \frac{\eta_s \dot{\gamma}}{\sigma}$, which represents the ratio of lubrication to frictional forces. The Leighton number $Le$ defines a critical shear rate below which no steady flow without localization exists. In the frictional regime the shear flow is localized. The lubricated regime is not simply viscous: the ratio of shear to normal stresses remains constant, as in the frictional regime; moreover the velocity profile has a single universal form in both frictional and lubricated regimes. Finally, a discrepancy between local and global measurements of viscosity is identified, which suggests inhomogeneity of the material under flow., Comment: Accepted for publication by Physical Review Letters (december 2004)

Published
2004

306. Nonergodic states of charged colloidal suspensions: Repulsive and attractive glasses and gels

Author

Daniel Bonn, Jacques Meunier, Hajime Tanaka, and Soft Matter (WZI, IoP, FNWI)

Subjects
Materials science, Condensed matter physics, Isotropy, Intermediate region, Condensed Matter::Disordered Systems and Neural Networks, Coulomb repulsion, Condensed Matter::Soft Condensed Matter, symbols.namesake, Colloid, symbols, Gel state, Elasticity (economics), van der Waals force, Phase diagram
Abstract

Two types of isotropic disordered nonergodic states exist in colloidal suspensions: glasses and gels. The difference between the two is that the nonergodicity, or elasticity, of gel stems from the existence of a percolated network, while that of glass stems from caging effects. Despite this clear difference in the origin of nonergodicity, it is not straightforward to distinguish the two states in a clear manner. Taking a Laponite suspension as an explicit example, we propose a general phase diagram for charged colloidal systems. It follows that a transition from the glass to the gel state can be induced by changing the interparticle interactions from predominantly repulsive to attractive. This originates from the competition between electrostatic Coulomb repulsion and van der Waals attraction. If the repulsion dominates, the system forms a Wigner glass, while in a predominantly attractive situation it forms a gel. In the intermediate region, where both repulsive and attractive interactions play roles, it may form an attractive glass.

Published
2004

307. Spreading of non newtonian fluids on hydrophilic surfaces

Author

Salima RAFAI, Daniel Bonn, Arezki Boudaoud, Rafaï, Salima, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], rheology, spreading, non newtonian, singularity, complex fluid, contact line, [PHYS] Physics [physics]
Published
2004

308. Aging and shear rejuvenation of soft glassy materials

Author

Daniel Bonn, Hajime Tanaka, Jacques Meunier, and Philippe Coussot

Subjects
Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Colloid, Materials science, Viscoplasticity, Shear (geology), Rheology, Apparent viscosity, Composite material, Critical value, Rejuvenation, Complex fluid
Abstract

Structured fluids (concentrated suspensions, emulsions, gels⋯.) typically exhibit an apparent yield stress. We show here that for a number of these fluids, a unique yield stress cannot be defined. Instead, when solicited above a critical stress, typical yield stress fluids (gels, clay suspensions) and soft glassy materials (colloidal glasses) start flowing abruptly and subsequently accelerate. We demonstrate that the competition between the spontaneous restructuration (aging) and the destruction of the internal structure (‘shear rejuvenation’) lead to a bifurcation in rheological behavior. For a stress smaller than a (time‐dependent) critical value, the viscosity increases in time and the material eventually stops flowing. For a slightly larger stresses the viscosity decreases continuously in time and the flow accelerates. Thus the viscosity jumps discontinuously to infinity at the critical stress.

Published
2004

309. Long-Range critical wetting: Observation of a critical end point

Author

Jacques Meunier, Volker C. Weiss, Emanuel Bertrand, Daniel Bonn, Joseph Indekeu, Salima Rafaï, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre Alexandre Koyré - Centre de Recherche en Histoire des Sciences et des Techniques (CAK-CRHST), Muséum national d'Histoire naturelle (MNHN)-École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS), Rafaï, Salima, Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Gas-liquid and vacuum-liquid interfaces, Materials science, critical end point, Critical phenomena, General Physics and Astronomy, Thermodynamics, Wetting, 02 engineering and technology, 01 natural sciences, [PHYS] Physics [physics], Contact angle, chemistry.chemical_compound, Transition point, Liquid-liquid transitions, 0103 physical sciences, 010306 general physics, [PHYS]Physics [physics], Aqueous solution, Water, 021001 nanoscience & nanotechnology, Wetting transition, Hexane, Pentane, Glucose, chemistry, alkanes, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; Alkanes deposited on aqueous substrates exhibit two different types of wetting behavior: alternatively to the usual first-order wetting transition, a sequential-wetting scenario of a long-range critical wetting transition preceded by a first-order thin-thick transition may be observed. Here, we present the first successful experimental attempt to locate the transition point between the standard first-order wetting and the long-range critical wetting: a critical end point, observed in a mixture of pentane and hexane which is deposited on an aqueous solution of glucose. Furthermore, we present the first direct measurement of the contact angle in the intermediate wetting state (frustrated-complete wetting) in the sequential-wetting scenario of hexane on brine and compare to theoretical predictions.

Published
2004

310. Liquid rope coiling on a solid surface

Author

Maniya Maleki, Daniel Bonn, Ramin Golestanian, Neil M. Ribe, and Mehdi Habibi

Subjects
Physics, Physics::General Physics, Quantitative Biology::Biomolecules, Oscillation, media_common.quotation_subject, Solid surface, Physics::Medical Physics, General Physics and Astronomy, Mechanics, Inertia, Instability, Volumetric flow rate, Physics::Fluid Dynamics, Gravitation, Life Science, Falling (sensation), media_common, Rope
Abstract

We present an experimental study of the coiling instability of a liquid "rope" falling on a solid surface. Coiling can occur in three different regimes--viscous, gravitational, or inertial--depending on the fluid viscosity and density, the fall height, and the flow rate. The competition among the different forces causes the coiling frequency first to decrease and subsequently to increase with increasing height. We also observe an oscillation between two coiling states in the gravitational-to-inertial transitional range, reflecting the multivaluedness of the dependence of coiling frequency on fall height. The data can be rescaled in a universal way, and agree very well with numerically predicted coiling frequencies.

Published
2004

311. Turbulent drag reduction by polymers

Author

Daniel Bonn, Olivier Cadot, Stéphane Douady, Yacine Amarouchene, Christian Wagner, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, [PHYS]Physics [physics], Quantitative Biology::Biomolecules, Drag coefficient, Turbulence, Thermodynamics, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Boundary layer, Viscosity, Flow separation, Transition point, Parasitic drag, Drag, 0103 physical sciences, General Materials Science, 010306 general physics, ComputingMilieux_MISCELLANEOUS
Abstract

The reduction of turbulent energy dissipation by addition of polymers is studied experimentally. We first address the question of where the action of the polymers is taking place. Subsequently, we show that there is a direct correlation of drag reduction with the elongational viscosity of the polymers. For this, the reduction of turbulent energy dissipation by addition of the biopolymer DNA is studied. These results open the way for a direct visualization study of the polymer conformation in a turbulent boundary layer.

Published
2004

312. FLOW OF COMPLEX FLUIDS

Author

Daniel Bonn and Jacques Meunier

Subjects
Materials science, Flow (mathematics), Mechanics, Complex fluid
Published
2003

313. Intrinsic route to melt fracture in polymer extrusion : a weakly nonlinear subcritical instability of viscoelastic Poiseuille flow

Author

Wim van Saarloos, Cornelis Storm, Christian Wagner, Bernard Meulenbroek, Daniel Bonn, and Volfango Bertola

Subjects
Materials science, Plastics extrusion, General Physics and Astronomy, Die swell, Mechanics, Hagen–Poiseuille equation, Instability, Viscoelasticity, Physics::Geophysics, Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Nonlinear system, Fracture (geology), Extrusion
Abstract

As is well known, the extrusion rate of polymers from a cylindrical tube or slit (a "die") is in practice limited by the appearance of "melt fracture" instabilities which give rise to unwanted distortions or even fracture of the extrudate. We present the results of a weakly nonlinear analysis which gives evidence for an intrinsic generic route to melt fracture via a weakly nonlinear subcritical instability of viscoelastic Poiseuille flow. This instability and the onset of associated melt fracture phenomena appear at a well-defined ratio of the elastic stresses to viscous stresses of the polymer solution.

Published
2003

314. Gravity drainage in porous media : the effect of wetting

Author

N. Shahidzadeh-Bonn, Philippe Vié, Emanuel Bertrand, J.P. Dauplait, J.C. Borgotti, Daniel Bonn, Laboratoire Central des Ponts et Chaussées (LCPC), Liquides Ioniques et Interfaces Chargées (LI2C), Université Pierre et Marie Curie - Paris 6 (UPMC)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Bertrand, Emanuel

Subjects
Petroleum engineering, Water injection (oil production), 02 engineering and technology, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, 01 natural sciences, Petroleum reservoir, 6. Clean water, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Natural gas field, Hexane, chemistry.chemical_compound, Fuel Technology, 020401 chemical engineering, chemistry, Wetting, 0204 chemical engineering, Drainage, Composite material, Oil field, Porous medium, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

In order to relate the wetting properties at the pore scale to the macroscale hydrodynamics, a series of benchmark experiments on the effect of the wetting on flow in porous media were performed. Gravity drainage of hexane (oil) in a model porous medium consisting of water-wet sand was studied using γ-ray densitometry and weight measurements. The advantage of our system is that we know and control the wetting properties perfectly: we can tune the wetting properties by changing the salinity of the water. This allows us to perform porous medium flow experiments for the different wetting states without changing the transport properties (viscosity and density) of the oil. Drainage is found to be more efficient and, consequently, oil recovery more important for partial wetting.

Published
2003

315. What Controls the Thickness of Wetting Layers near Bulk Criticality?

Author

Denis Fenistein, Gerard H. Wegdam, Salima Rafaï, Margarida M. Telo da Gama, Andrew O. Parry, Daniel Bonn, Jacques Meunier, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Phase transition, Materials science, Condensed matter physics, Critical phenomena, General Physics and Astronomy, Thermodynamics, Wetting, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Solid-liquid transitions, Theorem of corresponding states, Condensed Matter::Soft Condensed Matter, symbols.namesake, Critical point (thermodynamics), 0103 physical sciences, symbols, van der Waals force, 010306 general physics, 0210 nano-technology, Critical exponent, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Wetting layer
Abstract

We study the thickness of wetting layers in the binary-liquid mixture cyclohexane methanol. Far from the bulk critical point, the wetting layer thickness is independent of temperature, resulting from the competition between van der Waals and gravitational forces. Upon approaching the bulk critical temperature [t=(T(c)-T)/T(c)-->0], we observe that the wetting layer thickness diverges as t(-beta) with effective critical exponent beta=0.23+/-0.06. This is characteristic of a broad, intermediate scaling regime for the crossover from van der Waals wetting to critical scaling. We predict beta=beta/3 approximately 0.11, with beta the usual bulk-order parameter critical exponent, showing a small but significant difference with experiment.

Published
2002

316. Viscosity bifurcation in granular materials, foams, and emulsions

Author

Philippe Coussot, F. da Cruz, François Chevoir, and Daniel Bonn

Subjects
Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Thixotropy, Materials science, Material type, Critical stress, Rheology, Shear (geology), Thermodynamics, Porous medium, Granular material, Bifurcation
Abstract

We show that the rheological properties of dry granular materials, as well as foams and emulsions, are similar to typical thixotropic fluids: under a sufficiently strong shear the viscosity decreases in time, leading to a hysteresis in an up-and-down stress ramp. This leads to a viscosity bifurcation around a critical stress: for smaller stresses, the viscosity increases in time and the material eventually stops flowing, whereas for slightly larger stresses the viscosity decreases continuously with time and the flow accelerates. These results show that all jammed systems exhibit strong mechanical similarities around the transition between a ‘‘fluid’’ and a ‘‘solid’’ state, and that the transition between these states is discontinuous. This similarity is further emphasized by the fact that both a simple model for the dynamics of a grain on a sandpile @Quartier et al., Phys. Rev. E 62, 8299 ~2000!# and a simple model for the thixotropic behavior of ~colloidal! pastes @Coussot et al., Phys. Rev. Lett. 88, 175501 ~2002!# extrapolated to granular flows qualitatively predict this viscosity bifurcation.

Published
2002

317. Laponite: Aging and Shear Rejuvenation of a Colloidal Glass

Author

Hajime Tanaka, Sorin Tanase, Daniel Bonn, Bérengère Abou, and Jacques Meunier

Subjects
Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Shear rate, Nonlinear system, Diffusion dynamics, Colloid, Materials science, Shear (geology), Rheology, Particle dynamics, General Physics and Astronomy, Thermodynamics
Abstract

We study the nonlinear rheological behavior and the microscopic particle dynamics for a colloidal glass, to see whether recently developed models for driven glassy systems can be applied to predict the rheology. Qualitatively, all the findings predicted by the models can be retrieved in our system. Notably, the viscosity decreases strongly with the shear rate. Since it is difficult to predict non-Newtonian viscosities of colloidal systems due to long-ranged hydrodynamic interactions, this shows the promise of this approach for predicting flow behavior. In addition, the measurements allow us to relate the microscopic diffusion dynamics to the macroscopic viscosity of the system.

Published
2002

318. What controls the thickness of a wetting layer?

Author

Denis Fenistein, Daniel Bonn, Salima RAFAI, Wegdam, G. H., Meunier, J., Telo Da Gama, M., Parry, A., Rafaï, Salima, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
wetting, [PHYS.COND.CM-SM] Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], fluctuations, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], critical phenomena, [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], phase transitions, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], [PHYS.PHYS.PHYS-CHEM-PH] Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph]
Published
2002

319. Superspreading: aqueous surfactant drops spreading on hydrophobic surfaces

Author

Dipak K. Sarker, Daniel Bonn, Salima Rafaï, Vance Bergeron, Jacques Meunier, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Rafaï, Salima

Subjects
Marangoni, Aqueous solution, Chemistry, surfactant, 02 engineering and technology, Surfaces and Interfaces, Spreading, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, [PHYS.PHYS.PHYS-CHEM-PH] Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0104 chemical sciences, Chemical engineering, Pulmonary surfactant, Hydrophobic surfaces, surface tension, Electrochemistry, Organic chemistry, General Materials Science, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, Spectroscopy
Abstract

However, a fullquantitativeunderstandingoftheinfluenceofsurfactantaddition on the spreading dynamics is still lacking.In this note, we study the effect of surfactant additiononthespreadingrateofaqueousdropletsonhydrophobicsurfaces. We show that with comparable equilibriumsurface tensions, certain surfactants accelerate the spread-ing, whereas others slow it down. We demonstrate thatthe mechanism of the accelerated “superspreading”

Published
2002

320. Stick-slip instability for viscous fingering in a gel

Author

Daniel Bonn, Christian Wagner, J.-M. di Meglio, Georges Debregeas, N. Puff, D. Higgins, Institut Charles Sadron (ICS), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Jean Perrin (LJP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Biologie Paris Seine (IBPS), Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Arxiv, Import

Subjects
Materials science, Aqueous solution, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], FOS: Physical sciences, General Physics and Astronomy, Mechanics, Slip (materials science), Condensed Matter - Soft Condensed Matter, 01 natural sciences, Instability, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], 010305 fluids & plasmas, Viscous fingering, body regions, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Rheology, 0103 physical sciences, Soft Condensed Matter (cond-mat.soft), 010306 general physics, Scaling, Nonlinear Sciences::Pattern Formation and Solitons, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

The growth dynamics of an air finger injected in a visco-elastic gel (a PVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the standard Saffmann-Taylor instability, we observe - with increasing finger velocities - the existence of two new regimes: (a) a stick-slip regime for which the finger tip velocity oscillates between 2 different values, producing local pinching of the finger at regular intervals, (b) a ``tadpole'' regime where a fracture-type propagation is observed. A scaling argument is proposed to interpret the dependence of the stick-slip frequency with the measured rheological properties of the gel., Comment: 7 pages, 4 figures. Submitted to Europhysics Letters

Published
2002

321. Wetting transitions

Author

Daniel Bonn, David Ross, Emanuel Bertrand, Karine Ragil, Noushine Shahidzadeh, Daniel Broseta, Jacques Meunier, Bertrand, Emanuel, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Statistics and Probability, 0103 physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, 010306 general physics, 0210 nano-technology, Condensed Matter Physics, 01 natural sciences, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience

Published
2002

322. Wetting of alkanes on water

Author

Daniel Bonn, Joseph Indekeu, Ht Dobbs, Emanuel Bertrand, Daniel Broseta, Noushine Shahidzadeh, Jacques Meunier, Karine Ragil, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
Alkane, chemistry.chemical_classification, 02 engineering and technology, 021001 nanoscience & nanotechnology, Geotechnical Engineering and Engineering Geology, 01 natural sciences, Petroleum reservoir, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], chemistry.chemical_compound, Fuel Technology, Brine, Adsorption, chemistry, Chemical engineering, 0103 physical sciences, Petroleum, Geotechnical engineering, Wetting, 010306 general physics, 0210 nano-technology, Porous medium, Porosity, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS
Abstract

The wetting behavior of oil on water (or brine) has important consequences for the transport properties of oil in water-containing porous reservoirs, and consequently for oil recovery. The equilibrium wetting behavior of model oils composed of pure alkanes or alkane mixtures on brine is reviewed in this paper. Intermediate between the partial wetting state, in which oil lenses coexist on water with a thin film of adsorbed alkane molecules, and the complete wetting state, in which a macroscopically thick oil layer covers the water, these systems display a third, novel wetting state, in which oil lenses coexist with a mesoscopic (a few-nanometers-thick) oil film. The nature and location of the transitions between these wetting regimes depend on oil and brine compositions, temperature and pressure.

Published
2002

323. Synaptic counts approximate synaptic contact area in Drosophila.

Author

Christopher L Barnes, Daniel Bonnéry, and Albert Cardona

Subjects
Medicine, Science
Abstract

The pattern of synaptic connections among neurons defines the circuit structure, which constrains the computations that a circuit can perform. The strength of synaptic connections is costly to measure yet important for accurate circuit modeling. Synaptic surface area has been shown to correlate with synaptic strength, yet in the emerging field of connectomics, most studies rely instead on the counts of synaptic contacts between two neurons. Here we quantified the relationship between synaptic count and synaptic area as measured from volume electron microscopy of the larval Drosophila central nervous system. We found that the total synaptic surface area, summed across all synaptic contacts from one presynaptic neuron to a postsynaptic one, can be accurately predicted solely from the number of synaptic contacts, for a variety of neurotransmitters. Our findings support the use of synaptic counts for approximating synaptic strength when modeling neural circuits.

Published
2022
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324. Wetting of biological lipids on aqueous substrates

Author

Jacques Meunier, Noushine Shahidzadeh, Daniel Bonn, and Alain Mavon

Subjects
Aqueous solution, Marangoni effect, Materials science, Molecular Conformation, Water, Lipids, Phase Transition, Sebum, Solutions, symbols.namesake, Spectrometry, Fluorescence, Brine, Microscopy, Fluorescence, Chemical engineering, Ellipsometry, Lipid droplet, Wettability, symbols, Biophysics, Microscopy, Polarization, Dewetting, Wetting, van der Waals force, Sweat
Abstract

We study the dynamics and final wetting state of skin lipids on water and brine by fluorescence microscopy and ellipsometry. When a lipid droplet is brought into contact with the water surface, a lipid wetting film spreads out rapidly by a Marangoni effect. Subsequently, this film undergoes a dewetting instability. However, the final equilibrium is not partial wetting. The film breaks up into droplets with a mesoscopic (approximately 50 A) film in between. These observations result from a subtle interplay between short- and long-range forces: surfactants naturally present in the lipids favor wetting, while the van der Waals forces oppose it. In addition, this reveals the likely organization of the hydrolipid film that covers and protects the skin.

Published
2001

325. Risk Factors and Sleep Intervention Considerations in Esports: A Review and Practical Guide

Author

Daniel Bonnar, Sangha Lee, Michael Gradisar, and Sooyeon Suh

Subjects
sleep, esports, risk factors, intervention, performance, Neurosciences. Biological psychiatry. Neuropsychiatry, RC321-571
Abstract

Esports is a booming global industry and has been officially included in the lead-up to the 2020 Olympics in Tokyo. Given that esports is a cognitive based activity, and sleep is well known to be critical for optimal cognitive functioning, our research group recently proposed that sleep might be an important determinant of esports performance. The focus of the current review was to expand our limited understanding regarding the role of sleep in esports by exploring risk factors for suboptimal sleep and developing an associated intervention framework. More specifically, we aimed to 1) examine how gaming culture and game genre might negatively influence sleep behaviour, 2) describe a conceptual model to explain how sub-optimal sleep occurs in esports, and 3) outline sleep intervention considerations that specifically meet the needs of esports athletes. We conclude that gaming culture and game genre could both impact the sleep behaviour of esports athletes, via cognitive and behavioural mechanisms. Furthermore, adapting Spielman’s three-factor model to esports may provide a useful and easy to understand conceptualisation for sub-optimal sleep in esports. Lastly, sleep interventions for traditional athletes can be suitably modified for esports but must be comprehensive and extend from a theoretically grounded conceptual model.

Published
2019
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326. Avalanche behavior in yield stress fluids

Author

Daniel Bonn, Philippe Coussot, H. T. Huynh, and QD Nguyen

Subjects
Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Colloid, Viscosity, Materials science, Critical stress, Rheology, Flow (psychology), General Physics and Astronomy, Mechanics, Granular material, Bifurcation
Abstract

We show that, above a critical stress, typical yield stress fluids (gels and clay suspensions) and soft glassy materials (colloidal glasses) start flowing abruptly and subsequently accelerate, leading to avalanches that are remarkably similar to those of granular materials. Rheometrical tests reveal that this is associated with a bifurcation in rheological behavior: for small stresses, the viscosity increases in time; the material eventually stops flowing. For slightly larger stresses the viscosity decreases continuously in time; the flow accelerates. Thus the viscosity jumps discontinuously to infinity at the critical stress. We propose a simple physical model capable of reproducing these effects.

Published
2001

327. Crossover from first-order to critical wetting: short-range tricritical wetting

Author

Anna Posazhennikova, Jacques Meunier, Joseph Indekeu, Daniel Bonn, and David L. Ross

Subjects
Alkane, chemistry.chemical_classification, Materials science, General Physics and Astronomy, Thermodynamics, chemistry.chemical_compound, chemistry, Mean field theory, Exponent, Ising model, Wetting, Nonane, Undecane, Critical exponent
Abstract

We study wetting in liquid mixtures of methanol and the n-alkanes. Mixing alkanes of different chain lengths, we can examine the crossover between critical (continuous) and first-order (discontinuous) wetting transitions. Measurements of the film thickness and surface specific heat exponent indicate that for carbon number n between 11 (undecane) and 9 (nonane), there is a crossover from first-order to critical wetting with a tricritical wetting point between an effective alkane carbon number of 9.6 and 10. The observed variation of the specific heat exponent in the tricritical region agrees fairly well with the predictions of a simple mean-field model with only short-range interactions.

Published
2001

328. Aging dynamics in a colloidal glass

Author

Bérengère Abou, Daniel Bonn, and Jacques Meunier

Subjects
Materials science, Diffusion, Dynamics (mechanics), Relaxation (NMR), Viscometer, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter::Soft Condensed Matter, Viscosity, Colloid, Nuclear magnetic resonance, Dynamic light scattering, Chemical physics, Phase (matter), 0103 physical sciences, 010306 general physics, 0210 nano-technology
Abstract

The aging dynamics of colloidal suspensions of Laponite, a synthetic clay, is investigated using dynamic light scattering (DLS) and viscometry after a quench into the glassy phase. DLS allows to follow the diffusion of Laponite particles and reveals that there are two modes of relaxation. The fast mode corresponds to a rapid diffusion of particles within ``cages'' formed by the neighboring particles. The slow mode corresponds to escape from the cages: its average relaxation time increases exponentially fast with the age of the glass. In addition, the slow mode has a broad distribution of relaxation times, its distribution becoming larger as the system ages. Measuring the concomitant increase of viscosity as the system ages, we can relate the slowing down of the particle dynamics to the viscosity.

Published
2001

329. Viscous Fingering in a Gel

Author

Daniel Bonn, Anke Lindner, and P. Coussot

Subjects
Materials science, Capillary action, technology, industry, and agriculture, Computer Science::Human-Computer Interaction, Mechanics, Viscous liquid, equipment and supplies, Instability, Capillary number, body regions, Physics::Fluid Dynamics, Shear rate, Viscous fingering, Viscosity, biological sciences, Newtonian fluid, natural sciences, Nonlinear Sciences::Pattern Formation and Solitons
Abstract

When a less viscous fluid pushes a more viscous fluid in a Hele-Shaw cell, the interface between the two fluids develops an instability leading to the formation of fingerlike patterns, called viscous fingers. This is the so-called Saffman-Taylor or viscous fingering instability [1]. The width of these viscous fingers is, for Newtonian fluids, determined by the capillary number Ca = ΔμU/γ which represents the ratio of viscous forces over capillary forces; Δe is the viscosity difference between the two fluids, U the finger velocity and γ the surface tension. The viscous forces tend to narrow the finger, whereas the capillary forces tend to widen it: the width of the finger decreases with increasing finger velocity. Due to its relative simplicity the viscous fingering instability has received much attention as an archetype of pattern forming systems, both theoretically and experimentally [1, 2] and is by now well understood.

Published
2001

330. Fluctuation effects on wetting films

Author

Bernard P. Binks, Hamid Kellay, Daniel Bonn, Jacques Meunier, Emanuel Bertrand, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
Materials science, General Physics and Astronomy, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Surface tension, Hexane, chemistry.chemical_compound, Membrane, Wetting transition, Pulmonary surfactant, chemistry, 0103 physical sciences, Physical chemistry, Wetting, 010306 general physics, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Physics::Atmospheric and Oceanic Physics, ComputingMilieux_MISCELLANEOUS
Abstract

We provide a quantitative experimental determination of the fluctuation repulsion that stabilizes wetting films in systems for which the interfacial tension of one of the two interfaces bounding the wetting film is low. This is achieved by studying the wetting of different alkanes on water, in the presence of a surfactant. The results agree well with the theoretical calculation of the fluctuation repulsion of a membrane under vanishing surface tension.

Published
2001

331. Complex wetting phenomena in liquid mixtures: Frustrated-complete wetting and competing intermolecular forces

Author

Karine Ragil, Noushine Shahidzadeh, H. Dobbs, AI Posazhennikova, Joseph Indekeu, Daniel Broseta, Jacques Meunier, Emanuel Bertrand, Daniel Bonn, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
Mesoscopic physics, Chemistry, Critical phenomena, Intermolecular force, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, London dispersion force, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Wetting transition, Chemical physics, 0103 physical sciences, Physical chemistry, General Materials Science, Dewetting, Wetting, 010306 general physics, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, Wetting layer
Abstract

We give a phenomenological overview of recently discovered complex wetting states in simple liquid mixtures relevant to both fundamental research and industrial applications such as oil recovery. Alkanes on water show a sequence of two wetting transitions, from partial wetting to `frustrated-complete wetting', and finally to complete wetting: a first-order thin-thick transition between a microscopic and a mesoscopic adsorbed alkane film is followed by a long-range critical wetting transition to a macroscopic wetting layer. The existence of the new `frustrated-complete wetting' state follows from a competition between short-range and long-range components of the intermolecular forces, the latter opposing wetting. The effective long-range forces between interfaces consist of Debye dipolar and London dispersion contributions, which can also be in mutual competition. The London component is ultimately responsible for the frustration preventing complete wetting at ambient temperatures and pressures.

Published
2001

332. Controlling droplet deposition with polymer additives

Author

Jean Yves Martin, Daniel Bonn, Louis Vovelle, and Vance Bergeron

Subjects
chemistry.chemical_classification, Multidisciplinary, Aqueous solution, Drop (liquid), Kinetics, Aqueous two-phase system, Polymer, engineering.material, chemistry, Rheology, Coating, Chemical engineering, engineering, Organic chemistry, Wetting
Abstract

Controlling the impact of drops onto solid surfaces is important for a wide variey of coating and deposition processes--for example, the treatment of plants with herbicides and pesticides requires precise targeting in order to meet stringent toxicological regulations. However, the outer wax-like layer of the leaves is a non-wetting substrate that causes sprayed droplets to rebound; often less than 50% of the initial spray is retained by the plant. Although the impact and subsequent retraction of non-wetting aqueous drops on a hydrophobic surface have been the subjects of extensive experimental and theoretical work, non-newtonian rheological effects have not been considered in any detail. Here we report that, by adding very small amounts of a flexible polymer to the aqueous phase, we can inhibit droplet rebound on a hydrophobic surface and markedly improve deposition without significantly altering the shear viscosity of the solutions. Our results can be understood by taking into account the non-newtonian elongational viscosity, which provides a large resistance to drop retraction after impact, thereby suppressing droplet rebound.

Published
2000

333. Dynamics of wetting layer formation

Author

Daniel Bonn, Jacques Meunier, R. Blossey, Emanuel Bertrand, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
Materials science, Thermodynamic equilibrium, business.industry, Hamaker constant, Nucleation, General Physics and Astronomy, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], symbols.namesake, Optics, Wetting transition, Phase (matter), 0103 physical sciences, symbols, Wetting, van der Waals force, 010306 general physics, 0210 nano-technology, business, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, Wetting layer
Abstract

We study the formation and growth of wetting layers in the binary liquid mixture cyclohexane- methanol. By progressively deuterating the methanol we can tune the equilibrium wetting layer thick- ness. Hysteresis of the transition is observed for large thicknesses and is absent for thinner ones. This can be understood by calculating the activation energy for wetting layer nucleation as a function of the film thickness. We also show that the late-stage growth of the wetting layer after the nucleation process follows a power law in time, in agreement with a diffusion-limited growth mechanism proposed theoretically. PACS numbers: 68.45.Gd, 68.10. - m lating the nucleation probability for the thick film, it turns out that the nucleation probability decreases rapidly with increasing film thickness so that in some cases long-lived metastable states can indeed be observed, whereas in other cases they cannot. We also show that the growth of the wetting layer towards its final equilibrium state is driven by the long-range van der Waals forces and limited by dif- fusion. Thus we arrive at a complete characterization of the dynamics of this first-order surface phase transition. We study the demixed binary liquid system of cyclo- hexane and methanol at the critical composition. Previous studies (2,9) demonstrated that upon approaching the up- per consolute temperature Tc from below, a wetting layer of the heavier methanol-rich phase intrudes between the cyclohexane-rich phase and the vapor. Three different kinds of methanol are used, which differ in their degree of deuteration: one is normal methanol CH3OH, one is partly deuterated CH3OD, and one is completely deuter- ated CD3OD. This specific system is used because for normal methanol, the two liquid phases are almost den- sity matched. By progressive deuteration, we can subse- quently reach density differences characteristic of those for other binary liquid systems (3). The main effect of the deuteration is a change in the density difference. The other parameters, notably the Hamaker constant A, re- main virtually unchanged. Explicit calculation, follow- ing the method outlined by Israelachvili (10), yields A 8.5 6 0.5 3 10 223 J for the three systems T 25 ± C. Ellipsometry (11) is used to study the thickness of the wetting layer. The measured quantity is the ellipticity at the Brewster angle; using the Drude equation (12), the ellipticity can be related to the integral of the dielectric constant profile in the interfacial region. Considering the intruding wetting layer as a slab, the ellipticity is directly proportional to the thickness of the wetting layer. Here, we are interested only in the formation of the equilibrium wetting layer, starting out from a thin film. We consequently discuss the dynamics of wetting and do

Published
2000

334. First-order and critical wetting of alkanes on water

Author

H. T. Dobbs, Jacques Meunier, Joseph Indekeu, Daniel Broseta, Daniel Bonn, Emanuel Bertrand, Bertrand, Emanuel, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Alkane, chemistry.chemical_classification, Materials science, General Physics and Astronomy, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, First order, 01 natural sciences, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Chain length, Wetting transition, chemistry, Ellipsometry, Critical point (thermodynamics), 0103 physical sciences, Wetting, 010306 general physics, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, Phase diagram
Abstract

Ellipsometry measurements of the wetting behavior of different alkanes on water show a sequence of two wetting transitions: a first-order (discontinuous) transition followed by a critical (continuous) one. We report temperature-induced wetting transitions for different alkanes and a novel pressure-induced wetting transition for an alkane mixture. The experiments enable us to determine the global wetting phase diagram as a function of chain length and temperature which we subsequently calculate theoretically. The two transition lines are found to be approximately parallel, in accordance with basic theoretical arguments. PACS numbers: 68.10. – m, 64.70.Ja, 68.45.Gd

Published
2000

335. Coupling between flow and structure for a lamellar surfactant phase

Author

O. Greffier, Aurélien Léon, Hamid Kellay, Daniel Bonn, Jacques Meunier, Amer Al-Kahwaji, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Milieux Denses (IPEC), Pôle Universitaire Européen de Nancy-Metz, Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS), and Bergeret, Bernadette

Subjects
Materials science, Nucleation, General Physics and Astronomy, Thermodynamics, 02 engineering and technology, 01 natural sciences, Viscoelasticity, [PHYS] Physics [physics], Physics::Fluid Dynamics, Viscosity, Optics, Pulmonary surfactant, Lamellar phase, 0103 physical sciences, Lamellar structure, 010306 general physics, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Rheometry, business.industry, fungi, food and beverages, 021001 nanoscience & nanotechnology, Condensed Matter::Soft Condensed Matter, Shear (geology), 0210 nano-technology, business
Abstract

The flow-structure relation of lamellar phases is studied using rheometry and cross-polarized microscopy under flow. The equilibrium phases show different defects. Low salinities lead to very viscous, "onion" phases, whereas at high salinity, a low viscosity plane lamellar phase is found. Under shear, the latter shows a sudden transition to a viscoelastic gel, with a texture and viscosity very similar to that of the onions. Gelation occurs after a certain delay time, increasing rapidly with salinity, by the nucleation of onions. This allows one to relate the delay time to the defect energy.

Published
2000

336. Bertrand, Bonn, and Meunier reply

Author

Daniel Bonn, Jacques Meunier, Emanuel Bertrand, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
Materials science, 010304 chemical physics, 0103 physical sciences, General Physics and Astronomy, Art history, 010306 general physics, 01 natural sciences, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience

Published
2000

337. Yield Stress Fluids Slowly Yield to Analysis

Author

Daniel Bonn, Morton M. Denn, and Soft Matter (WZI, IoP, FNWI)

Subjects
Propellant, Stress (mechanics), Cement, Multidisciplinary, Materials science, Yield (engineering), Settling, Critical stress, Flow (psychology), Radioactive waste, Composite material
Abstract

We are surrounded in everyday life by yield stress fluids: materials that behave as solids under small stresses but flow like liquids beyond a critical stress. For example, paint must flow under the brush, but remain fixed in a vertical film despite the force of gravity. Food products (such as mayonnaise), other consumer products (such as toothpaste), concrete, and even radioactive nuclear waste sludge exhibit yield stresses. The yield stress may serve to keep particulate fillers from settling, as in many consumer products and gelled propellants, or determine whether bubbles remain trapped in cement. For handling and using these materials, it is paramount to know the stress at which the material starts to flow, but a consensus on the mechanical behavior of these materials is only slowly emerging.

Published
2009

338. Optical studies of low-dimensional phase transitions

Author

Noushine Shahidzadeh, Jacques Meunier, Ludovic Pauchard, Daniel Bonn, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Statistics and Probability, Phase transition, Langmuir, Brewster's angle, Materials science, business.industry, Condensed Matter Physics, symbols.namesake, Optics, Wetting transition, Chemical physics, Ellipsometry, Free surface, symbols, Wetting, Thin film, business, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; Optical techniques such as ellipsometry and Brewster angle and fluorescence microscopy have considerably enhanced our understanding of the physics of thin films. We discuss a few recent results obtained by these techniques. In the domain of wetting phase transitions, ellipsometry experiments have revealed that long range forces can split the classical first order wetting transition into two transitions: a first order transition followed by a second order or critical wetting transition upon increasing the temperature. For Langmuir films, a single molecular layer of an insoluble amphiphilic at the free surface of water, the properties of a number of condensed phases have been studied using Brewster angle and fluorescence microscopy. Unexpected and surprising results have been obtained for both the fracture properties and the melting of two-dimensional crystals.

Published
1999

339. Wetting of hydrocarbon mixtures on water under varying pressure or composition

Author

Jacques Meunier, Daniel Bonn, Emanuel Bertrand, Daniel Broseta, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Bertrand, Emanuel

Subjects
chemistry.chemical_classification, Alkane, Equation of state, Hamaker constant, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Geotechnical Engineering and Engineering Geology, 01 natural sciences, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Pentane, Hexane, chemistry.chemical_compound, Fuel Technology, Hydrocarbon, chemistry, 0103 physical sciences, Wetting, Binary system, 010306 general physics, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS
Abstract

The wetting/spreading properties of oil on water in the presence of gas are related to the Hamaker constant W of the water/oil/gas system: a negative W corresponds to a stable thick (macroscopic) oil film wetting water, whereas a positive W corresponds to oil lenses that do not wet water. A simple calculation scheme is presented in this paper, based on a combination of an approximation of the Dzyaloshinskii–Lifshitz–Pitaevskii (DLP) theory and either an adequate equation of state or refractive index measurements, to predict the wetting properties as a function of thermodynamic variables such as temperature, pressure and fluid composition. This paper also presents ellipsometry measurements of the wetting behavior of a propane/ n -hexane binary system on water at 20°C under varying pressure (controlled by the injection of the gaseous propane component into the ellipsometry cell). These measurements indicate that this system displays the same wetting behavior and goes through the same sequence of wetting transitions under increasing pressures as those encountered for pure n -alkanes (e.g., n -pentane or n -hexane) under increasing temperatures. Namely, we observed upon increasing the pressure (or the propane content in the system) a transition between the usual partial wetting state (at low pressures), and the so-called pseudo-partial wetting state, in which oil lenses coexist with an oil film with thickness ≈100 A. A continuous (or critical) transition between this pseudo-partial wetting state and complete wetting occurs for a higher pressure corresponding to the vanishing of the Hamaker constant W . Our expectation is that most condensates and volatile oils (or at least those mostly composed of alkanes) spread on brines under reservoir (high pressures and temperature) conditions.

Published
1999

340. Wetting Phase Transitions and Petroleum Reservoirs

Author

Daniel Bonn, Jacques Meunier, Daniel Broseta, Karine Ragil, and Joseph Indekeu

Subjects
chemistry.chemical_compound, symbols.namesake, Phase transition, Wetting transition, Chemistry, Phase (matter), Flow (psychology), symbols, Petroleum, Thermodynamics, Wetting, van der Waals force, Porosity
Abstract

The wetting properties of oil on water are relevant to the industrial problem of oil recovery from porous reservoirs. The location of wetting phase transitions, a subject of fundamental interest for experimentalists and theorists, is also of practical importance for petroleum engineering because the hydrodynamics of oil flow is different on either side of the transition. This seminar treats the application of the phenomenological wetting theory of Cahn to fluids with van der Waals forces, and in particular to alkanes on water. Including the long-range substrate-adsorbate interaction in the theory allows one to reproduce the experimentally observed sequence of two wetting-like transitions. A critical wetting transition, which arises from the subtle action of the van der Waals forces, is preceded by a first-order transition between a thin and a thick film at a lower temperature. The three wetting regimes separated by these two transitions presumably lead to three different oil recovery efficiencies.

Published
1999

341. Aging of a colloidal 'Wigner' glass

Author

Hajime Tanaka, Daniel Bonn, Jacques Meunier, Hamid Kellay, Gerard H. Wegdam, WZI (IoP, FNWI), Centre de physique moléculaire optique et hertzienne (CPMOH), Université Sciences et Technologies - Bordeaux 1-Centre National de la Recherche Scientifique (CNRS), and Bergeret, Bernadette

Subjects
[PHYS]Physics [physics], Materials science, Condensed matter physics, Relaxation (NMR), General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, [PHYS] Physics [physics], Condensed Matter::Soft Condensed Matter, Low volume, Colloid, Correlation function, 0103 physical sciences, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

We study the aging of a colloidal glass, which is obtained for extremely low volume fractions due to strong electrostatic repulsions, leading to the formation of a "Wigner glass". During the aging, a new crossover between a complete and incomplete decay of the correlation function is observed, accompanied by an increase in the non-ergodicity parameter. The dynamics can be described as a cage-diffusion process. For short times, the escape of the particles from "cages" formed by neighbouring particles dominates; for long times the particles cannot escape anymore and the system becomes strongly non-ergodic.

Published
1999

342. In Situ Quantitative Measurement of Concentration Profiles in a Microreactor with Submicron Resolution Using Multiplex CARS Microscopy

Author

Mischa Bonn, Jan H. van Maarseveen, Daniel Bonn, Michiel Müller, Dawn Schafer, Jeffrey A. Squier, Soft Matter (WZI, IoP, FNWI), Synthetic Organic Chemistry (HIMS, FNWI), and Molecular Cytology (SILS, FNWI)

Subjects
In situ, Pyrrolidines, Chemistry, Microfluidics, Resolution (electron density), technology, industry, and agriculture, Analytical chemistry, Infrared spectroscopy, General Chemistry, Hydrogen-Ion Concentration, Microfluidic Analytical Techniques, Spectrum Analysis, Raman, Biochemistry, Catalysis, symbols.namesake, Colloid and Surface Chemistry, Microscopy, symbols, Microreactor, Image resolution, Raman scattering, Acetic Acid
Abstract

In situ quantitative imaging of concentration profiles of reactants and products inside a microfluidic reactor is achieved, with submicron spatial resolution with similar to mM sensitivity and on similar to ms time scales, for a given position. The label-free approach relies on quantitative vibrational spectroscopy, using Coherent Anti-Stokes Raman scattering microscopy in a spectrally resolved fashion, and is demonstrated on an elementary acid-base reaction.

Published
2008

343. Photoperiodic control of the seasonal variations in the daily pattern of melatonin synthesis in the European hamster, Cricetus cricetus

Author

Bruno Pitrosky, André Malan, Daniel Bonn, Berthe Vivien-Roels, Paul Pévet, Mohamed Zitouni, and B. Canguilhem

Subjects
Daily pattern, photoperiodism, medicine.medical_specialty, General Neuroscience, Photoperiod, Biology, biology.organism_classification, Pineal Gland, General Biochemistry, Genetics and Molecular Biology, European hamster, Circadian Rhythm, Melatonin, Pineal gland, medicine.anatomical_structure, Endocrinology, History and Philosophy of Science, Internal medicine, Cricetinae, medicine, Animals, Melatonin synthesis, Circadian rhythm, Seasons, medicine.drug
Published
1998

344. Delayed fracture of an inhomogeneous soft solid

Author

Michaël Prochnow, Hamid Kellay, Jacques Meunier, Daniel Bonn, and Karim Ben-Djemiaa

Subjects
chemistry.chemical_classification, Multidisciplinary, Materials science, Nucleation, Mineralogy, Activation energy, Mechanics, Polymer, Fractal dimension, Breaking strength, Physics::Geophysics, Condensed Matter::Soft Condensed Matter, chemistry, Fracture (geology), Delayed fracture, Polymer gel, Computer Science::Databases
Abstract

The spontaneous fracture of polymer gels was studied. Contrary to crystalline solids, where fracture usually happens instantaneously at a well-defined breaking strength, the fracture of a polymer gel can occur with a delay. When a constant force was applied, the cracks nucleated and started to propagate after a delay that can be as long as 15 minutes, depending on the force. This phenomenon can be understood by calculating the activation energy for crack nucleation in arbitrary dimension and accounting for the inhomogeneity of the gel network in terms of its fractal dimension.

Published
1998

345. Viscous fingering and related instabilities in complex fluids

Author

Daniel Bonn, Hamid Kellay, Jacques Meunier, and Bergeret, Bernadette

Subjects
chemistry.chemical_classification, Chemistry, Capillary action, General Chemical Engineering, General Physics and Astronomy, Thermodynamics, Polymer, Non-Newtonian fluid, [PHYS] Physics [physics], body regions, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Viscous fingering, Surface tension, Hele-Shaw flow, Pulmonary surfactant, Chemical physics, ComputingMilieux_MISCELLANEOUS, Complex fluid
Abstract

We study the viscous fingering instability for different polymer and surfactant solutions. For the polymers, for similar non-Newtonian viscosities, the results are strikingly different; flexible polymers widen the viscous fingers, whereas stiff polymers narrow the fingers. We show that the difference is due to normal stress effects; these are large for the flexible polymer and undetectable for the stiff polymer. For the surfactant systems, two different regimes are found. For low surfactant concentrations, the dominant effect occurs at the surface; the advection of surfactant molecules from the interface results in dynamic surface tension. For high concentrations, volume effects become important, notably the non-Newtonian flow properties of the surfactant phases, which leads to the formation of extremely thin fracture-like fingers.

Published
1998

346. Bonn and Indekeu reply

Author

Joseph Indekeu and Daniel Bonn

Subjects
Information retrieval, Materials science, General Physics and Astronomy
Published
1996

347. Viscous fingering in complex fluids

Author

M. Ben Amar, Hamid Kellay, Jacques Meunier, M. Bräunlich, Daniel Bonn, Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre de physique moléculaire optique et hertzienne (CPMOH), Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1, Max-Planck-Institut für Chemie (MPIC), Max-Planck-Gesellschaft, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Statistics and Probability, Materials science, Capillary action, Thermodynamics, Viscous liquid, Condensed Matter Physics, 01 natural sciences, Instability, Capillary number, 010305 fluids & plasmas, Surface tension, Viscous fingering, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Viscosity, 0103 physical sciences, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], ComputingMilieux_MISCELLANEOUS, Complex fluid
Abstract

International audience; Viscous fingers form when in a thin linear channel a fluid pushes a more viscous fluid. The instability of the interface results from a competition between viscous and capillary forces. We show here by acting on the viscosity or the surface tension by means of surfactants or polymers that the instability can be modified drastically. For the two different systems, unlike in the classical system, the width of the finger can go through a minimum and increases with increasing velocity before settling at a plateau value larger than half the channel width. A numerical resolution of the relevant hydrodynamic equations reveals that these large deviations from the classical result can be interpreted in terms of a velocity dependent dynamic interfacial tension for the surfactant system and viscosity for the polymer solution.

Published
1995

348. VISCOUS FINGER WIDENING WITH SURFACTANTS AND POLYMERS

Author

Daniel Bonn, Jacques Meunier, Hamid Kellay, M. Ben Amar, Bergeret, Bernadette, Centre de physique moléculaire optique et hertzienne (CPMOH), and Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1

Subjects
[PHYS]Physics [physics], Maximum bubble pressure method, Materials science, Capillary action, General Physics and Astronomy, Mechanics, 01 natural sciences, Instability, Capillary number, 010305 fluids & plasmas, [PHYS] Physics [physics], Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Viscous fingering, Surface tension, Viscosity, Settling, 0103 physical sciences, 010306 general physics, ComputingMilieux_MISCELLANEOUS
Abstract

We study the viscous fingering instability which results from a competition between capillary and viscous forces. We show that for two different systems the instability is modified drastically by changing the surface tension or viscosity by means of surfactants or polymers. For both systems the width of the finger can increase with increasing velocity before settling at a plateau value larger than half the channel width. A numerical study shows that the large deviations from the classical result can be attributed to a velocity dependence of the dynamic interfacial tension and viscosity.

Published
1995

350. Pattern formation by dewetting and evaporating sedimenting suspensions

Author

Daniel Bonn, Mehdi Habibi, Abdoulaye Fall, Peder Moller, Salima Rafaï, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département Electronique et Physique (TSP - EPH), Institut Mines-Télécom [Paris] (IMT)-Télécom SudParis (TSP), Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères] (LIPhy), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Soft Matter (WZI, IoP, FNWI), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Département Electronique et Physique (EPH), and Fall, Abdoulaye

Subjects
Length scale, Materials science, Evaporation, Pattern formation, 01 natural sciences, [PHYS] Physics [physics], 010305 fluids & plasmas, Viscosity, Optics, 0103 physical sciences, Life Science, Dewetting, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Thin film, 010306 general physics, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], business.industry, Contact line, General Chemistry, Condensed Matter Physics, [PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Chemical physics, Particle, business, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat]
Abstract

Pattern formation from drying droplets containing sedimenting particles and dewetting of thin films of such suspensions was studied. The dewetting causes the formation of finger-like patterns near the contact line which leave behind a deposit of branches. We find that the strikingly low speed of dewetting is due to the high particle concentration in the contact line region, leading to a strongly enhanced viscosity. For pattern formation from drying droplets (containing particles), evaporation also causes dewetting. In both cases, we find a similar relationship between the size of the patterns and the dewetting speed. The coefficient of this relationship gives us the effective viscosity at the contact line. We present a simple model that accounts for this, and that shows that the size of the particles is the relevant length scale in both problems.

Published
2012

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