Université PSL

Publications

RECHERCHER

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RAB-35 and ARF-6 GTPases Mediate Engulfment and Clearance Following Linker Cell-Type Death
Laboratoire pour la biologie quantitative du développement - Kutscher LM, Keil W, Shaham S
Dev Cell - 47(2) 222-238 - doi: 10.1016/j.devcel.2018.08.015. - 2018
Clearance of dying cells is essential for development and homeostasis. Conserved genes mediate apoptotic cell removal, but whether these genes control non-apoptotic cell removal is a major open question. Linker cell-type death (LCD) is a prevalent non-apoptotic developmental cell death process with features conserved from C. elegans to vertebrates. Using microfluidics-based long-term in vivo imaging, we show that unlike apoptotic cells, the C. elegans linker cell, which dies by LCD, is competitively phagocytosed by two neighboring cells, resulting in cell splitting. Subsequent cell elimination does not require apoptotic engulfment genes. Rather, we find that RAB-35 GTPase is a key coordinator of competitive phagocytosis onset and cell degradation. RAB-35 binds CNT-1, an ARF-6 GTPase activating protein, and removes ARF-6, a degradation inhibitor, from phagosome membranes. This facilitates phosphatidylinositol-4,5-bisphosphate removal from phagosome membranes, promoting phagolysosome maturation. Our studies suggest that RAB-35 and ARF-6 drive a conserved program eliminating cells dying by LCD.
High density gold nanoparticles immobilized on surface via plasma deposited APTES film for decomposing organic compounds in microchannels
Laboratoire Procédés - Plasmas - Microsystèmes - XiRao, CédricGuyo, StephanieOgnier, Bradley Da Silva, Chenglin Chu, MichaëlTatoulian, Ali AbouHassan
Applied Surface Science - 439 272-281 - https://doi.org/10.1016/j.apsusc.2018.01.009 - 2018
Immobilization of colloidal particles (e.g. gold nanoparticles (AuNps)) on the inner surface of micro-/nano- channels has received a great interest for catalysis. A novel catalytic ozonation setup using a gold-immobilized microchannel reactor was developed in this work. To anchor AuNps, (3-aminopropyl) triethoxysilane (APTES) with functional amine groups was deposited using plasma enhanced chemical vapor deposition (PECVD) process. The results clearly evidenced that PECVD processing exhibited relatively high efficiency for grafting amine groups and further immobilizing AuNPs. The catalytic activity of gold immobilized microchannel was evaluated by pyruvic acid ozonation. The decomposition rate calculated from High Performance Liquid Chromatography (HPLC) indicated a much better catalytic performance of gold in microchannel than that in batch. The results confirmed immobilizing gold nanoparticles on plasma deposited APTES for preparing catalytic microreactors is promising for the wastewater treatment in the future.

Isothermal crystallization of glycine in semi-continuous mode by anti-solvent addition
Laboratoire Procédés - Plasmas - Microsystèmes - Wail El Bazi, Marie-Thérèse Moufarej Abou Jaoude, Catherine Porte, Isabelle Mabille
Journal of Crystal Growth - 3 498 - DOI: 10.1016/j.jcrysgro.2018.06.013 - 2018
This article focuses on the isothermal semi-continuous crystallization of glycine aqueous solution by adding an anti-solvent, ethanol. The effect of the ethanol concentration on solubility and the impact of the ethanol flow rate on the metastable zone width and on the size distribution of the crystals were investigated. The study showed that increasing the ethanol concentration in the medium decreases solubility for the studied temperatures and that increasing the ethanol flow rate causes a widening of the metastable zone without inducing any noticeable effect on the crystals’ size distribution. In addition, nucleation kinetic models were determined for two temperatures (30 and 56 °C).
Microfluidic chips for plasma flow chemistry: application to controlled oxidative processes
Laboratoire Procédés - Plasmas - Microsystèmes - Julien Wengler, Stéphanie Ognier, Mengxue Zhang, Etienne Levernier, Cedric Guyon, Cyril Ollivier, Louis Fensterbank and Michael Tatoulian
Reaction Chemistry & Engineering - 3 930-941 - https://doi.org/10.1039/C8RE00122G - 2018
The present paper reports the integration of nonthermal plasma into a biphasic gas–liquid microfluidic chip. It evaluates the potential of plasma activation to become a synthetic tool in organic chemistry, operating under mild conditions (room temperature, atmospheric pressure) and without a catalyst. Few preceding works on plasma chemistry involved a liquid phase and none of them was able to handle the high reactivity of plasma to achieve both high conversion rates and selective reactions. We fabricated a glass-polymer microfluidic chip comprising a one metre long serpentine channel, in which a parallel gas–liquid flow was stabilized thanks to a specific step-like cross-sectional shape. Transparent ITO electrodes, deposited on both sides of the chip and linked to an AC high voltage source, produced a dielectric barrier discharge along the channel. We assessed the behaviour of the flow through optical observations and characterized the discharge through electrical measurements and real time intensified-CCD monitoring. We report the successful treatment of liquid cyclohexane with oxygen plasma inside our chip. The GC analysis of the outflowing liquid revealed only a partial oxidation of cyclohexane into a mixture of cyclohexanol and cyclohexanone (industrially known as “KA oil”), and cyclohexyl hydroperoxide, with a total selectivity above 70% and conversion up to 30%. This indicates that alkanes can be activated and functionalized by means of plasma discharges, in a controlled way. In that respect, we claim to have successfully overcome some of the barriers to industrially relevant plasma chemistry. We believe that the combined use of plasma and microfluidic technologies is essential to the development of this new field of research.
Cover Picture: Plasma Process. Polym
Laboratoire Procédés - Plasmas - Microsystèmes - Fatemeh Rezaei Yury Gorbanev Michael Chys Anton Nikiforov Stijn W. H. Van Hulle Paul Cos Annemie Bogaerts Nathalie De Geyter
First published - 15 6 - doi.org/10.1002/ppap.201870013 - 2018
Front Cover: Electrospinning solutions of polylactic acid in chloroform and 5,5‐N‐dimethylformamide were subjected to preelectrospinning plasma treatment (PEPT). A broad range of spectroscopic analytical techniques, mainly EEM and EPR, were performed to investigate the plasma‐induced chemistry in the organic solutions. The enhanced conductivity of the solutions was ascribed to the formation of plasma‐induced acids during PEPT. The synergistic effect of chemical changes leads to poly lactic acid nanofibers with uniform morphology.

Further details can be found in the article by Fatemeh Rezaei et al. (e1700226).
Electrostrictive polymer composites based on liquid crystalline graphene for mechanical energy harvesting
MIE - Matériaux Innovants pour l'Energie - Jinkai Yuan, Wilfrid Neri, Cécile Zakri, Philippe Poulin, Annie Colin
Multifunctional Materials - 43922 - - 2018
High electromechanical coupling is critical to perform effective conversion between mechanical and electrical energy for various applications of electrostrictive polymers. Herein, a giant electrostriction effect is reported in liquid crystalline graphene doped dielectric elastomers. The materials are formulated by an original phase transfer method which allows the solubilization of graphenic monolayers in non-polar solvents. Dielectric spectroscopy is combined with tensile test devices to measure the true electrostriction coefficients with differentiating the Maxwell stress effect. Because of their unique liquid crystal structure, the resultant composites show a giant relative permittivity and ultralarge electrostriction coefficient. This work offers a promising pathway to design novel high performance electrostrictive polymer composites as well as to provide insights into mechanisms of true electrostriction in electrically …
Microporous electrostrictive materials for vibrational energy harvesting
MIE - Matériaux Innovants pour l'Energie - Mickaël Pruvost, Wilbert J Smit, Cécile Monteux, Philippe Poulin, Annie Colin
Multifunctional Materials - 1 15004 - - 2018
We present electrostrictive materials with excellent properties for vibrational energy harvesting applications. The developed materials consist of a porous carbon black composite, which is processed using water-in-oil emulsions. In combination with an insulating layer, the investigated structures exhibit a high effective relative dielectric permittivity (up to 182 at 100 Hz) with very low effective conductivity (down to 2.53 10− 8 S m− 1). They can generate electrical energy in response to mechanical vibrations with a power density of 0.38 W m− 3 under an applied bias electric field of 32 V. They display figures or merit for energy harvesting applications well above reference polymer materials in the field, including fluorinated co-and ter-polymers synthetized by heavy chemical processes. The production process of the present materials is based on non hazardous and low-cost chemicals. The soft dielectric materials are …
Shear Rheology Control of Wrinkles and Patterns in Graphene Oxide Films
MIE - Matériaux Innovants pour l'Energie - Franco Tardani, Wilfrid Neri, Cécile Zakri, Hamid Kellay, Annie Colin, Philippe Poulin
Langmuir - 9(34) 2996-3002 - - 2018
Drying graphene oxide (GO) films are subject to extensive wrinkling, which largely affects their final properties. Wrinkles were shown to be suitable in biotechnological applications; however, they negatively affect the electronic properties of the films. Here, we report on wrinkle tuning and patterning of GO films under stress-controlled conditions during drying. GO flakes assemble at an air–solvent interface; the assembly forms a skin at the surface and may bend due to volume shrinkage while drying. We applied a modification of evaporative lithography to spatially define the evaporative stress field. Wrinkle alignment is achieved over cm2 areas. The wavelength (i.e., wrinkle spacing) is controlled in the μm range by the film thickness and GO concentration. Furthermore, we propose the use of nanoparticles to control capillary forces to suppress wrinkling. An example of a controlled pattern is given to elucidate the …
All-organic microelectromechanical systems integrating electrostrictive nanocomposite for mechanical energy harvesting
MIE - Matériaux Innovants pour l'Energie - Hussein Nesser, Hélène Debéda, Jinkai Yuan, Annie Colin, Philippe Poulin, Isabelle Dufour, Cédric Ayela
Nano energy - 44 43983 - - 2018
Recent advances in the field of microelectromechanical systems (MEMS) have generated great interest in the substitution of inorganic microcantilevers by organic ones, due to their low cost, high flexibility and a simplified fabrication by means of printing methods. Here, we present the integration of electrostrictive nanocomposites into organic microcantilever resonators specifically designed for mechanical energy harvesting from ambient vibrations. Strain sensitive nanocomposite materials composed of reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) are integrated into all-organic MEMS by means of an innovative low-cost and environment friendly process by combining printing techniques and xurography. Static tests of the electrostrictive nanocomposite with 3.7 wt% rGO show good performances with variations of capacitance that exceeds 4% for strain values lower than 0.55% as the …
Giant Electrostriction of Soft Nanocomposites Based on Liquid Crystalline Graphene
MIE - Matériaux Innovants pour l'Energie - Jinkai Yuan, Alan Luna, Wilfrid Neri, Cécile Zakri, Annie Colin, Philippe Poulin
ACS nano - 12(2) 1688-1695 - - 2018
High electromechanical coupling is critical to perform effective conversion between mechanical and electrical energy for various applications of electrostrictive polymers. Herein, a giant electrostriction effect is reported in liquid crystalline graphene-doped dielectric elastomers. The materials are formulated by a phase-transfer method which allows the solubilization of graphenic monolayers in nonpolar solvents. Dielectric spectroscopy is combined with tensile test devices to measure the true electrostriction coefficients with differentiating the Maxwell stress effect. Because of their liquid crystal structure, the resultant composites show an ultralarge electrostriction coefficient (∼10–14 m2/V2 at 0.1 Hz) coupled with good reproducibility during cycles at high deformation rates. This work offers a promising pathway to design high-performance electrostrictive polymer composites as well as to provide insights into mechanisms …

414 publications.