Effect of shear on a lyotropic lamellar phase

Diat, Olivier; Roux, D.; Nallet, Frédéric

doi:10.1051/jp2:1993211

Cited by 420 publications

(699 citation statements)

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“…It is presumably similar to the one described by Oswald and KlŽman for thermotropic systems [8]. At higher shear rate or for more dilute systems, a new state appears where the smectic layers (membranes) form multilayer spherical droplets of well defined size, controlled by the shear rate, ranging typically from 10 mm to less than 1 mm (region 2) [5] and [9]. At even higher shear rates, a state where the membranes are parallel to the flow with the smectic director parallel to the gradient of velocity direction is stable.…”

Section: Reofêsicas De Fases Laminaressupporting

confidence: 68%

“…It is stabilized by undulation interactions [7]. Using Couette cells and different techniques, we have shown that a shear diagram can be described corresponding to different orientations of the smectic layers respecting the flow field [5] (see Fig. 1).…”

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 96%

“…We have been able to show that the orientation taken by a lyotropic lamellar phase under shear can be described as steady states separated by transitions as a function of the characteristic distance between membranes and the shear rate [5]. Three different states of orientation of the lamellar phase have been described: an isotropic state where the membranes form onion-like structures (multilayer spherical objects of size R much larger than the repeating distance d) exists at intermediate shear rates in between two other states (at either lower or higher shear rates) where layers are mainly parallel to the flow.…”

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 98%

“…This diagram exhibits three states of orientation as shown in ref. [5]. At very low shear rates (g × < 1 s Ð1 ) and high surfactant concentrations, the membranes are mainly parallel to the flow with the smectic director parallel to the velocity gradient direction (region 1).…”

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 98%

“…Three different states of orientation of the lamellar phase have been described: an isotropic state where the membranes form onion-like structures (multilayer spherical objects of size R much larger than the repeating distance d) exists at intermediate shear rates in between two other states (at either lower or higher shear rates) where layers are mainly parallel to the flow. The location of these regions in the shear rate/smectic-period plane has been called the shear diagram [5] (see Fig. 1).…”

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 99%

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Rheophysics of Lamellar Phases

Roux

1997

Rev. Inst. Fr. Pét.

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RHƒOPHYSIQUES DE PHASES LAMELLAIRESNous avons dŽveloppŽ plusieurs techniques pour Žtudier l'effet du cisaillement sur des fluides complexes. Ces techniques sont basŽes sur des cellules de cisaillement spŽcialement adaptŽes aux techniques de dispersion ou aux propriŽtŽs de transport. Une courte description des cellules sera donnŽe en m•me temps que les rŽsultats qui ont pu •tre obtenus en utilisant ces techniques. Des exemples sur les syst•mes lyotropes seront dŽcrits en dŽtail. RHEOPHYSICS OF LAMELLAR PHASESWe have developed several techniques to study the effect of shear on complex fluids. These techniques are based on shear cells specially adapted to scattering techniques or transport properties. A brief description of the cells will be given together with the results that can be obtained using these techniques. Exemples on lyotropic systems will be detailed.

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Section: Reofêsicas De Fases Laminaressupporting

confidence: 68%

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 96%

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 98%

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 98%

Section: Reofêsicas De Fases Laminaresmentioning

confidence: 99%

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Rheophysics of Lamellar Phases

Roux

1997

Rev. Inst. Fr. Pét.

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Engineering Lipid Spherulites for the Sustained Release of Highly Dosed Small Hydrophilic Compounds

Montanari

Krupke

Leroux

2023

Adv Healthcare Materials

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Currently, there is a lack of parenteral sustained release formulations for the delivery of highly dosed small hydrophilic drugs. Therefore, parenteral lipid spherulites are engineered capable of entrapping large amounts of such compounds and spontaneously releasing them in a sustained fashion. A library of spherulites is prepared with a simple green process, using phosphatidylcholine (PC) and/or phosphatidylethanolamine (PE), nonionic surfactants and water. The vesicle formulations exhibiting appropriate size distribution and morphology are selected and loaded with 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), ((OEG 2 ) 2 -IP4), an inositol phosphate derivative currently under clinical evaluation for the treatment of aortic valve stenosis. The loading efficiency of spherulites is up to 12.5-fold higher than that of liposomes produced with the same materials. While the PC-containing vesicles showed high stability, the PE spherulites gradually lost their multilayer organization upon dilution, triggering the active pharmaceutical ingredient (API) release over time. In vitro experiments and pharmacokinetic studies in rats demonstrated the ability of PE spherulites to increase the systemic exposure of (OEG 2 ) 2 -IP4 up to 3.1-fold after subcutaneous injection, and to completely release their payload within 3-4 d. In conclusion, PE spherulites represent a promising lipid platform for the extravascular parenteral administration of highly dosed small hydrophilic drugs.

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Multilamellar‐Vesicle‐Assisted Electrodeposition of Inorganic Nanodots

et al. 2006

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Dots with dimensions below 100 nm are important in materials science for their original properties (luminescence, magnetism, catalysis, etc.), [1] and have been used to achieve higher data-storage densities, increased signal intensities, and higher reactivities, finding use in the computer industry, biotechnology, and catalysis. Although several techniques such as electron-and ion-beam lithography and scanning-probe methods are available today for producing nanostructures with size-dependent properties, [2][3][4] these are so expensive and time consuming that they hardly fulfill industrial requirements. Other techniques such as those based on masked surfaces [5,6] are less costly but are multistep approaches and usually limited to metallic deposition. We report a new process that combines a low-cost implementation and only a single step to produce nanodots over large areas with controlled size and density. This process is based on multilamellar vesicles, which serve as nanovectors. They incorporate metal ions such as copper ions, and under an appropriate electric field they can be directed towards an electrode. The reduction of ions on the electrode causes metal-nanodot production. Their density is controlled by the vesicle density and their size by the electric-field parameters.The manufacture of dots with sizes below 100 nm is motivated firstly by the specific properties exhibited by such nanostructures. These properties are due to surface effects and size reduction.[1] As an example, quantum dots are crystalline particles of semiconductor materials having unique optical properties. Since these are smaller in size than the wavelength of visible light, they cannot be seen under normal conditions, but become luminescent under UV light. The size of the particle controls the color of the emitted light. Also, magnetic nanostructures often exhibit interesting properties, such as when the sample size becomes comparable to that of the spin-flip diffusion length and magnetic-domain-wall width.[7]The production of small dots of controlled size usually requires very sophisticated techniques. A highly efficient technique for the deposition of monodisperse and size-controlled clusters on surfaces uses size-selected molecular beams.[8] Dots with a controlled number of atoms are then produced by laser evaporation or a sputter source. Electron-beam [2] or ion-beam lithography, [3] or nanolithography with scanning probe microscopes [4,9] such as dip-pen lithography, [10] are other examples of available techniques for deposition of dots with controlled size. However, these bottom-up techniques are so costly due to intricate fabrication processes and expensive equipment, and so time-consuming because of their step-by-step processes, that they are unsuitable as mass-production techniques.In some applications, like biosensor, biomaterial, or catalytic applications, the number of dots and the surface coverage are also of importance. Tailoring both features is essential to obtain functional structures inducing measurable signals [11]...

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Effect of shear on a lyotropic lamellar phase

Cited by 420 publications

References 0 publications

Rheophysics of Lamellar Phases

Rheophysics of Lamellar Phases

Engineering Lipid Spherulites for the Sustained Release of Highly Dosed Small Hydrophilic Compounds

Multilamellar‐Vesicle‐Assisted Electrodeposition of Inorganic Nanodots

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