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Matière Molle
(423) Articles dans des revues
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Dispersion and orientation of single-walled carbon nanotubes in a chromonic liquid crystal
Auteur(s): Ould-Moussa Nawell, Blanc C., Zamora-Ledezma C., D. Lavrentovich Oleg, I. Smalyukh Ivan, F. Islam Mohammad, G. Yodh A., Maugey Maryse, Poulin Philippe, Anglaret E., Nobili M.
(Article) Publié:
Liquid Crystals, vol. 40 p.1628-1635 (2013)
Ref HAL: hal-00794735_v1
DOI: 10.1080/02678292.2013.772254
WoS: 000328245700005
Exporter : BibTex | endNote
49 Citations
Résumé: A post-synthesis alignment of individual single-walled carbon nanotubes (SWCNTs) is desirable for translating their unique anisotropic properties to a macroscopic scale. Here, we demonstrate excellent dispersion, orientation and concomitant-polarised photoluminescence of SWCNTs in a nematic chromonic liquid crystal. The methods to obtain stable suspension are described, and order parameters of the liquid crystal matrix and of the nanotubes are measured independently.
Commentaires: 8 pages
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Fractures in complex fluids: the case of transient networks
Auteur(s): Ligoure C., Mora S.
(Article) Publié:
Rheologica Acta, vol. 52 p.91-114 (2013)
Texte intégral en Openaccess :
Ref HAL: hal-00776688_v1
DOI: 10.1007/s00397-012-0668-0
WoS: 000314408200001
Exporter : BibTex | endNote
53 Citations
Résumé: We present a comprehensive review of the cur- rent state of fracture phenomena in transient networks, a wide class of viscoelastic fluids. We will first define what is a fracture in a complex fluid and recall the main structural and rheological properties of transient networks. Secondly, we review experimental reports on fractures of transient networks in several configurations: shear-induced fractures, fractures in Hele-Shaw cells, and fracture in extensional geometries (filament-stretching rheometry and pendant drop experiments), including fracture propaga- tion. The tentative extension of the concepts of brittleness and ductility to the fracture mechanisms in transient net- works is also discussed. Finally, the different and appar- ently contradictory theoretical approaches developed to interpret fracture nucleation will be addressed and con- fronted to experimental results. Rationalized criteria to dis- criminate the relevance of these different models will be proposed.
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Shape of an elastic loop strongly bent by surface tension: Experiments and comparison with theory
Auteur(s): Mora S., Phou T., Fromental J.-M., Audoly Basile, Pomeau Yves
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 86 p.026119 (2012)
PMID 23005837
DOI: 10.1103/PhysRevE.86.026119
WoS: 000308133400002
16 Citations
Résumé: When a very flexible wire is dipped into a soapy solution, it collapses onto itself. We consider the regions of high curvature where the wire folds back onto itself, enclosing a capillary film. The shapes of these end loops are measured in experiments using soap films and compared to a known similarity solution. The sizes of these structures provide a simple and reliable way to measure surface tension.
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Experimental study of z resolution in acousto-optical coherence tomography using random phase jumps on ultrasound and light
Auteur(s): Lesaffre Max, Farahi Salma, Ramaz François, Gross M.
(Article) Publié:
Applied Optics, vol. 52 p.949-957 (2013)
Texte intégral en Openaccess :
Ref HAL: hal-00785372_v1
Ref Arxiv: 1302.1343
DOI: 10.1364/AO.52.000949
WoS: 000314842400005
Ref. & Cit.: NASA ADS
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2 Citations
Résumé: Acousto-Optical Coherence Tomography (AOCT) is a variant of Acousto Optic Imaging (also called Ultrasound modulated Optical Tomography) that makes possible to get resolution along the ultrasound propagation axis $z$. We present here new AOCT experimental results, and we study how the $z$ resolution depends on time step between phase jumps $T_\phi$, or on the correlation length $\Delta z$. By working at low resolution, we perform a quantitative comparison of the $z$ measurements with the theoretical Point Spread Function (PSF). We present also images recorded with different $z$ resolution, and we qualitatively show how the image quality varies with $T_\phi$, or $\Delta z$.
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Study of Antibacterial Activity by Capillary Electrophoresis Using Multiple UV Detection Points
Auteur(s): Oukacine Farid, Romestand Bernard, Goodall David M., Massiera G., Garrelly Laurent, Cottet Hervé
(Article) Publié:
Analytical Chemistry, vol. 84 p.3302-3310 (2012)
Ref HAL: hal-00777465_v1
PMID 22448657
DOI: 10.1021/ac300004t
WoS: 000302829800038
Exporter : BibTex | endNote
11 Citations
Résumé: A new methodology for an antibacterial assay based on capillary electrophoresis with multiple UV detection points has been proposed. The possible antibacterial activity of cationic molecules on bacteria (Gram-positive and Gramnegative) is studied by detecting the bacteria before, during, and after their meeting with the cationic antibacterial compound. For that, a UV area imaging detector having two loops and three detection windows was used with a 95 cm ×100 μm i.d. capillary. In the antibacterial assay, the bacteria (negatively charged) and the cationic molecules were injected separately from each end of the capillary. The bacteria were mobilized by anionic ITP mode while cationic molecules migrate in the opposite direction under conditions close to CZE. The cationic molecules were injected into the capillary as a broad band (injected volume about 16% of the volume of the capillary) to prevent dilution of the sample during the electrophoretic process. Bacteriolytic activity, as well as strong interactions between the small antibacterial molecules and the bacteria, can be investigated within a few minutes. The assay was used to study the antibacterial activity of dendrigraft poly-L-lysines on Micrococcus luteus and Erwinia carotovora. Because dendrigraft poly-L-lysines are nonimmunogenic and have low toxicity, this new class of dendritic biomacromolecules is very promising for antibacterial applications.
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Red Blood Cell Membrane Dynamics during Malaria Parasite Egress
Auteur(s): Callan-Jones A., Albarran O., Massiera G., Lorman V., Abkarian M.
(Article) Publié:
Biophysical Journal, vol. 103 p.2475-2483 (2012)
Texte intégral en Openaccess :
Ref HAL: hal-00802240_v1
PMID 23260049
DOI: 10.1016/j.bpj.2012.11.008
WoS: 000312527500009
Exporter : BibTex | endNote
17 Citations
Résumé: Precisely how malaria parasites exit from infected red blood cells to further spread the disease remains poorly understood. It has been shown recently, however, that these parasites exploit the elasticity of the cell membrane to enable their egress. Based on this work, showing that parasites modify the membrane's spontaneous curvature, initiating pore opening and outward membrane curling, we develop a model of the dynamics of the red blood cell membrane leading to complete parasite egress. As a result of the three-dimensional, axisymmetric nature of the problem, we find that the membrane dynamics involve two modes of elastic-energy release: 1), at short times after pore opening, the free edge of the membrane curls into a toroidal rim attached to a membrane cap of roughly fixed radius; and 2), at longer times, the rim radius is fixed, and lipids in the cap flow into the rim. We compare our model with the experimental data of Abkarian and co-workers and obtain an estimate of the induced spontaneous curvature and the membrane viscosity, which control the timescale of parasite release. Finally, eversion of the membrane cap, which liberates the remaining parasites, is driven by the spontaneous curvature and is found to be associated with a breaking of the axisymmetry of the membrane.
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Thermo- and pH-sensitive aggregation behavior of PDEAm-b-P(L-lysine) double hydrophilic block copolymers in aqueous solution
Auteur(s): Xuewei Zhang, Monge Sophie, In M., Giani Olivia, Robin Jean-Jacques
(Article) Publié:
Soft Matter, vol. 9 p.1301-1309 (2013)
Ref HAL: hal-00769822_v1
DOI: 10.1039/c2sm27051j
WoS: 000312553900032
Exporter : BibTex | endNote
15 Citations
Résumé: The synthesis and the aggregation behavior of novel well-defined poly(N,N-diethylacrylamide)-b-poly- (L-lysine) (PDEAm-b-PLL) double hydrophilic block copolymers are reported. PDEAm-b-PLL was prepared using an original strategy which consisted of the ring opening polymerization (ROP) of N3- trifluoroacetyl-L-lysine N-carboxyanhydride using terminated-thiol PDEAm as a macroinitiator. After deprotection of the amine group of the L-lysine, pH- and thermo-sensitive poly(N,N-diethylacrylamide)- b-poly(L-lysine) block copolymers were obtained. The structure of the copolymers was characterized by 1H NMR and FT-IR. Then, pH and temperature sensitivities were measured by 1H NMR and UV/Vis spectroscopy. At different pH values and temperatures, poly(L-lysine) and poly(N,N-diethylacrylamide) showed typical behaviors, which led to different types of aggregation in aqueous solution. The influence of both stimuli was carefully investigated by DLS, TEM, and SANS.
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