Novel route to mono- and diglycerides synthesis in miniemulsion catalyzed by lipases

In summary, it could be shown that the lipolysis and glycerolysis in miniemulsion catalyzed by lipases lead to a significant increase of selectivity and presents an important route to obtain mono- and diglycerides. The miniemulsion offers an interfacial area, which allows increasing the yields and the kinetics of reactions. The reaction mechanism of most lipases is ruled by the interfacial activation between the oil phase and the aqueous phase. In this dissertation, a screening of lipases has been done and a sn-1,3 specific lipase was chosen not only to study the lipolysis and the glycerolysis in miniemulsion but also the influence of the homogeneity of the miniemulsion and the influence of the miniemulsion interfacial area through the variation of the miniemulsion droplet size. First of all, the lipolyses of tricaprylin catalyzed by the Rhizopus Arrhizus lipase, by the Pseudomonas Cepacia lipase, and by the Rhizomucor Miehei lipase were carried out and compared using the free fatty acid titration and 1H-NMR. Secondly, the homogeneity of the miniemulsion was observed to be a parameter influencing not only the activity but also the regioselectivity. Thirdly, the miniemulsion specific surface area was observed to play a determining role in the interfacial activation. This variation shows a relation between the lipase catalytic activity and the miniemulsion specific surface area. Fourthly, the glycerolysis reaction of tricaprylin by Rhizopus Arrhizus lipase in miniemulsion was studied. Finally, the hydrolysis of tricaprylin by weak bases in miniemulsion was performed to study their selectivity and activity. Like the caustic soda, some weak bases show a strong uncontrolled activity until they are used at high concentrations and under defined temperature conditions. Otherwise, the activity of the weak bases remains low. A thermodynamic selectivity is observed leading to the preferential formation of the thermodynamic stable isomers, 1,3-diglyceride and 1-monoglyceride

Propriétés de transport de membranes de verre en milieu sel fondu

Des mesures de potentiels de membranes de verre « Pyrex » dans des mélanges nitrate de lithium-nitrate de sodium fondus ont pu être interprétés par l’équation d’Eisenman (1959-1967) dont le paramètre n est pris égal à 1, conformément à la théorie le Lesourd, Peneloux et Doucet (1975). On aboutit, à 357 °C, à une constante de sélectivité de l’ion lithium par rapport à l’ion sodium de 0,53 ± 0,04 et à un paramètre d’interaction dans le mélange nitrate de lithium-nitrate de sodium fondu (solution « simple » au sens de Guggenheim) de — 590 ± 250 cal. mol-1. La détermination des nombres de transport des ions lithium et sodium dans la membrane conduit à une valeur de la constante de sélectivité en bon accord avec le chiffre donné ci-dessus

Thin-dielectric-layer engineering for 3D nanostructure integration using an innovative planarization approach

International audienceThree-dimensional (3D) nanostructures are emerging as promising building blocks for a large spectrum of applications. One critical issue in integration regards mastering the thin, flat, and chemically stable insulating layer that must be implemented on the nanostructure network in order to build striking nano-architectures. In this letter, we report an innovative method for nanoscale planarization on 3D nanostructures by using hydrogen silesquioxane as a spin-on-glass (SOG) dielectric material. To decouple the thickness of the final layer from the height of the nanostructure, we propose to embed the nanowire network in the insulator layer by exploiting the planarizing properties of the SOG approach. To achieve the desired dielectric thickness, the structure is chemically etched back with a highly diluted solution to control the etch rate precisely. The roughness of the top surface was less than 2 nm. There were no surface defects and the planarity was excellent, even in the vicinity of the nanowires. This newly developed process was used to realize a multilevel stack architecture with sub-deca-nanometer-range layer thickness

Propriétés de transport de membranes de verre en milieu sel fondu

Un calcul des coefficients phénoménologiques d’Onsager dans les membranes de verre est présenté. Ce calcul permet d’aboutir à une expression inédite des conductivités des verres mixtes, et donne directement l’équation d’Eisenman des potentiels de membranes à courant nul. L’existence d’un potentiel d’asymétrie non nul apparaît comme une conséquence nécessaire de la théorie, qui est appliquée à la détermination des propriétés thermodynamiques des solutions en contact avec la membrane. Pour cette détermination, la connaissance des propriétés thermodynamiques n’est pas nécessaire

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Novel route to mono- and diglycerides synthesis in miniemulsion catalyzed by lipase

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Towards greener nanoimprint processes

The purpose of this work is to develop nano-imprint processes using “greener” polymers. PLA, a bio-sourced, bio-degradable and bio-compatible polymer, will be directly nano-structured via a thermal nano-imprint process (T-NIL). PVA, a synthetic bio-compatible and bio-degradable polymer, will be used as water-soluble sacrificial layers for lift-off process

Towards greener nanoimprint processes

The purpose of this work is to develop nano-imprint processes using “greener” polymers. PLA, a bio-sourced, bio-degradable and bio-compatible polymer, will be directly nano-structured via a thermal nano-imprint process (T-NIL). PVA, a synthetic bio-compatible and bio-degradable polymer, will be used as water-soluble sacrificial layers for lift-off process

Wet thermal oxidation of AlAsSb for lateral confinement in GaSb-based VCSELs

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Fabrication of versatile calibration samples for 3D super-resolution optical imaging with <5nm Z resolution using greyscale e-beam lithography and Nano-Imprint replication

National audienceWe present a 3D mold fabrication process to produce high precision calibration samples with few nanometers steps in the vertical direction. After imprinting into a resist layer of adequate refractive index using nano-imprint lithography, these molds can produce calibration samples valuable for super-resolution Direct Optical Nanoscopy with Axially Localized Detection (DONALD). This novel method is dedicated to the 3D mapping of labeled biomolecules into biological samples by fluorescence and requires calibration samples with well-characterized steps ranging from 5 nm to 125 nm in height