Ref HAL: hal-01303522_v1
DOI: 10.3390/ijms17020223
WoS: WOS:000371830800032
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13 Citations
Résumé:

Surface activity and micelle formation of alkylguanidinium chlorides, containing 10, 12, 14, and 16 carbon atoms in the hydrophobic tail have been studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr → LC and LC → I transitions, as well as their propensity of forming birefringent phases were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (micH°), were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.

Résumé:

Liquid sheets that freely expand in air can be produced by the impact of a small drop of liquid on a cylindrical target of size comparable to that of the drop. In this talk I will illustrate with two examples how the imaging with a fast camera of the dynamics of the sheets thus formed can shed light on fundamental and industrial issues. On the one hand, we quantify the interplay between elasticity and viscosity and the effects of a strong and fast deformation on viscoelastic droplets. On the other hand, we rationalize the role of dilute emulsions in the destabilization mechanism of liquid sheets and its consequence for anti-drift phenomena in agricultural sprays.

Résumé:

Liquid sheets that freely expand in air can be produced by the impact of a small drop of liquid on a cylindrical target of size comparable to that of the drop. In this talk I will illustrate with two examples how the imaging with a fast camera of the dynamics of the sheets thus formed can shed light on fundamental and industrial issues. On the one hand, we quantify the interplay between elasticity and viscosity and the effects of a strong and fast deformation on viscoelastic droplets. On the other hand, we rationalize the role of dilute emulsions in the destabilization mechanism of liquid sheets and its consequence for anti-drift phenomena in agricultural sprays.

Ref HAL: hal-01280723_v1
DOI: 10.1140/epje/i2016-16009-6
WoS: WOS:000369330800002
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9 Citations
Résumé:

Several techniques to assemble artificial lipid bilayers involve the zipping of monolayers. Theirefficiency is determined by the renewal of the saturated monolayers to be zipped and this proceeds byadsorption of lipids dispersed in oil as aggregates. The size of these lipids aggregates is a key parameterto ensure both the stability of the suspension and a fast release of lipids at the interface. We proposea new method inspired from the solvent-shifting nucleation process allowing to control and tune thelipid aggregates size and that improves the production of artificial membranes. It is simpler and fasterthan current methods starting from a dry lipid film, which are highly sensitive to environmental conditions.This method opens the route to bilayer production processes with new potentialities in membranecomposition.

Ref HAL: hal-01285518_v1
DOI: 10.1021/acs.analchem.5b03584
WoS: 000371371400019
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8 Citations
Résumé:

We introduce a new estimator of particle size polydispersity for dynamic light scattering data, which quantifies the relative width of the intensity-weighted distribution of diffusion coefficients. Simulated dynamic light scattering data are analyzed to (i) compare the accuracy and precision of the new polydispersity indicator to polydispersity measurements from standard cumulant and moment analysis (MA) fits and (ii) establish for each method the optimum data range for fitting. Although MA is preferable at low polydispersity, the new estimator is the most accurate and precise at intermediate and large polydispersities. Finally, we successfully apply the method proposed here to real data from colloidal particles, microgels, and polymer solutions.

Ref HAL: hal-01281406_v1
Ref Arxiv: 1511.07756
DOI: 10.1088/0953-8984/28/7/075201
WoS: 000368793200012
Ref. & Cit.: NASA ADS
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10 Citations
Résumé:

We introduce a temporal scheme for data sampling, based on a variable delay between two successive data acquisitions. The scheme is designed so as to reduce the average data flow rate, while still retaining the information on the data evolution on fast time scales. The practical implementation of the scheme is discussed and demonstrated in light scattering and microscopy experiments that probe the dynamics of colloidal suspensions using CMOS or CCD cameras as detectors.

Commentaires: Published in J. Phys.: Cond. Matter. 11 pages, 5 figures + Supporting Data (Python software to implement the method described in the manuscript)

Ref HAL: hal-01332698_v1
PMID 26835961
Ref Arxiv: 1511.04257
DOI: 10.1364/AO.55.0000A8
WoS: WOS:000369055100003
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
8 Citations
Résumé:

Heterodyne holography is a variant of phase shifting holography in which reference and signal arms are controlled by acousto optic modulators. In this review paper, we will briefy describe the method and its properties, and we will illustrate its advantages in experimental applications.

Commentaires: . Réf Journal: Appl. Opt. 55, A8-A16 (2016)