Fast and Adjustable Resolution Grazing Incidence x-ray Liquid Surfaces Diffraction achieved through 2D Detector

We developed a setup using a two dimensional camera for Grazing Incidence x-ray Diffraction (GIXD) on Langmuir monolayers and more generally for surface diffraction on two dimensional powders. Compared to the classical setup using a linear detector combined with Soller's slits, the acquisition time is reduced of a factor of at least 10 (from more than one hour to a few minutes) using the same x-ray source (synchrotron bending magnet) with a comparable signal to noise ratio. Moreover, using an horizontal gap slit, the experimental resolution can be adjusted and for small values of the gap, better resolution can be achieved compared to the one obtained with the linear detector.Comment: 37pages, 11 figure

Structure of smectic defect cores: an X-ray study of 8CB liquid crystal ultra-thin films

We study the structure of very thin liquid crystal films frustrated by antagonistic anchorings in the smectic phase. In a cylindrical geometry, the structure is dominated by the defects for film thicknesses smaller than 150 nm and the detailed topology of the defects cores can be revealed by x-ray diffraction. They appear to be split in half tube-shaped Rotating Grain Boundaries (RGB). We determine the RGB spatial extension and evaluate its energy per unit line. Both are significantly larger than the ones usually proposed in the literatureComment: 4 page

Interface-templated crystal growth in sodium dodecyl sulfate solutions with NaCl

Many ionic surfactants, such as sodium dodecyl sulphate (SDS) crystallize out of solution if the temperature falls below the crystallization boundary. The crystallization temperature is impacted by solution properties, and can be decreased with the addition of salt. We have studied SDS crystallization a t the liquid/vapor interfaces from solutions at high ionic strength (sodium chloride). We show that the surfactant crystals at the surface grow from adsorbed SDS molecules, as evidenced by the preferential orientation of the crystals identified using grazing incidence X-ray diffraction. We find a unique timescale f or the crystal growth from the evolution of structure, surface tension, and visual inspection, which can be controlled through varying the SDS or NaCl concentrations

Oxidation of Porphyrins in the Presence of Nucleophiles: From the Synthesis of Multisubstituted Porphyrins to the Electropolymerization of the Macrocycles

International audienc

Self-organized arrays of dislocations in thin smectic liquid crystal films

International audienceCombining optical microscopy, synchrotron X-ray diffraction and ellipsometry, we studied the internal structure of linear defect domains (oily streaks) in films of smectic liquid crystal 8CB with thickness 100-300 nm confined between air and a rubbed PVA polymer substrate which impose hybrid anchoring conditions (normal and unidirectional planar, respectively). We show how the presence or absence of dislocations control the structure of highly deformed thin smectic films. Each domain contains smectic layers curved in the shape of flattened hemicylinders to satisfy both anchoring conditions, together with grain boundaries whose size and shape are controlled by the presence of dislocation lines. A flat grain boundary normal to the interface connects neighboring hemicylinders, while a rotating grain boundary (RGB) is located near the axis of curvature of the cylinders. The RGB shape appears such that dislocation lines are concentrated at its summit close to the air interface. The smectic layers reach the polymer substrate via a transition region where the smectic layer orientation satisfies the planar anchoring condition over the entire polymer substrate and whose thickness does not depend on the one of the film. The strength of the planar anchoring appears to be high, larger than 10 −2 J/m 2 , compensating for the high energy cost of creating an additional 2D defect between an horizontal smectic layer and perpendicular ones. This 2D defect may be melted, in order to avoid the creation of a transition region structure composed of a large number of dislocations. As a result, linear defect domains can be considered as arrays of oriented defects, straight dislocations of various Burger vectors, whose location is now known and 2D nematic defects. The possibility of easy variation between the present structure with a moderate amount of dislocations and a structure with a large number of dislocations is also demonstrated

Influence of the Surface Chemistry of Metal-Organic Polyhedra in Their Assembly into Ultrathin Films for Gas Separation

The formation of ultrathin films of Rh-based porous metal-organic polyhedra (Rh-MOPs) by the Langmuir-Blodgett method has been explored. Homogeneous and dense monolayer films were formed at the air-water interface either using two different coordinatively alkyl-functionalized Rh-MOPs (HRhMOP(diz)12 and HRhMOP(oiz)12) or by in situ incorporation of aliphatic chains to the axial sites of dirhodium paddlewheels of another Rh-MOP (OHRhMOP) at the air-liquid interface. All these Rh-MOP monolayers were successively deposited onto different substrates in order to obtain multilayer films with controllable thicknesses. Aliphatic chains were partially removed from HRhMOP(diz)12 films post-synthetically by a simple acid treatment, resulting in a relevant modification of the film hydrophobicity. Moreover, the CO2/N2 separation performance of Rh-MOP-supported membranes was also evaluated, proving that they can be used as selective layers for efficient CO2 separation. © 2022 The Authors. Published by American Chemical Society

Comparison of the effect of lps and pam3 on ventilated lungs

<p>Abstract</p> <p>Background</p> <p>While lipopolysaccharide (LPS) from Gram-negative bacteria has been shown to augment inflammation in ventilated lungs information on the effect of Gram-positive bacteria is lacking. Therefore the effect of LPS and a lipopetide from Gram-positive bacteria, PAM3, on ventilated lungs were investigated.</p> <p>Methods</p> <p>C57/Bl6 mice were mechanically ventilated. Sterile saline (sham) and different concentrations of LPS (1 μg and 5 μg) and PAM3 (50 nM and 200 nM) were applied intratracheally. Lung function parameters and expression of MIP-2 and TNFα as well as influx of neutrophils were measured.</p> <p>Results</p> <p>Mechanical ventilation increased resistance and decreased compliance over time. PAM3 but not LPS significantly increased resistance compared to sham challenge (P < 0.05). Both LPS and PAM3 significantly increased MIP-2 and TNFα mRNA expression compared to sham challenge (P < 0.05). The numbers of neutrophils were significantly increased after LPS at a concentration of 5 μg compared to sham (P < 0.05). PAM3 significantly increased the numbers of neutrophils at both concentrations compared to sham (P < 0.05).</p> <p>Conclusions</p> <p>These data suggest that PAM3 similar to LPS enhances ventilator-induced inflammation. Moreover, PAM3 but not LPS increases pulmonary resistance in ventilated lungs. Further studies are warranted to define the role of lipopetides in ventilator-associated lung injury.</p