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Physique de systèmes biologiques
(40) Production(s) de l'année 2017
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Off-equilibrium surface tension in miscible fluids 
Auteur(s): Truzzolillo D., Cipelletti L.
(Article) Publié:
Soft Matter, vol. 13 p.13-21 (2017)
Ref HAL: hal-01499947_v1
DOI: 10.1039/c6sm01026a
WoS: WOS:000395374100002
Exporter : BibTex | endNote
14 Citations
Résumé: The interfacial tension between immiscible fluids is responsible for a wealth of every-day phenomena, from the spherical shape of small drops and bubbles to the ability to walk on water of many insects.More than a century ago, physicist and mathematician D. Korteweg postulated the existence of an effective interface tension for miscible fluids, whenever a composition gradient exists, as encountered, e.g., in many flow geometries. In this mini-review, we discuss experimental work performed in the last decades that demonstrates the existence of a positive effective interface tension in a variety of systems, from molecular, near-critical liquids to complex fluids such as polymer solutions and colloidal suspensions. The various experimental strategies that have been deployed are discussed, together with their advantages and limitations. Finally, some of the key theoretical questions still open are outlined.
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Impact of solid and liquid balls on a solid surface: an unified description
Auteur(s): Arora S., Fromental J.-M., Mora S., Phou T., Ramos L., Ligoure C.
Conference: APS March meeting 2017 (La Nouvelle-Orléans, US, 2017-03-12)
Ref HAL: hal-01495935_v1
Exporter : BibTex | endNote
Résumé: We study experimentally the impact of ultra soft spherical gel balls of millimetric size d0 on a rigid substrate covered by a thin layer of liquid nitrogen to avoid viscous dissipation. The balls largely deform like a pancake at high impact velocities. We measure the maximally deformed size dmax and the the time needed to reach this maximal size after impact τmax, versus the impact velocity ui for various elastic moduli. We do the same type of experiments with liquid droplets of various surface tensions. The experiments reveal a universal scaling behavior of the maximum deformation dmax/d0 of both solid balls and liquid drops provided that both bulk and surface elasticity are properly taken into account. Moreover, we show that, in absence of viscous dissipation, the dynamics of the system can be understood as a conventional spring-mass system with a stiffness given by a combination of surface tension and bulk elasticity and a mass given by that of the ball (or drop); the deformation of the small ball (drop) during the impact linearly depends on the impact velocity, and the contact time scales as the period of this spring-mass system.
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Bursting mechanism of dilute emulsion-based liquid sheets: anti-drift application for agricultural sprays
Auteur(s): Ligoure C.
Conférence invité: CROPS AND CHEMICALS EUROPE (BERLIN, DE, 2017-02-08)
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Selection of the tagged photons by off axis heterodyne holography in ultrasound-modulated optical tomography
Auteur(s): Gross M.
(Article) Publié:
Applied Optics, vol. 56 p.1846 - 1846 (2017)
Texte intégral en Openaccess : 
Ref HAL: hal-01474043_v1
Ref Arxiv: 1702.07378
DOI: 10.1364/AO.56.001846
WoS: 000395668400007
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
3 Citations
Résumé: Ultrasound-modulated optical tomography (UOT) is a technique that images optical contrast deep inside scattering media. Heterodyne holography is a promising tool able to detect the UOT tagged photons with high efficiency. In this work, we describe theoretically the detection of the tagged photon in heterodyne holography based UOT, show how to filter the untagged photon, and discuss the effect of shot noise. The discussion considers also speckle decorrelation. We show that optimal detection sensitivity can be reached, if the frame exposure time of the camera used to perform the holographic detection is of the order of the decorrelation time.
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