Search results for "synthesis"

Synthèse et réactivité chimiques et électrochimiques de dérivés d'imidazoliums : vers des procédés éco-responsables

2015

This work deals with the use of electrochemistry as a tool for alternative synthesis of new azolium-based molecules.A new electrosynthesis method was developed for the synthesis of imidazolium carboxylates (masked carbenes) leading to a wide library of compounds. This approach was compared to already reported chemical syntheses. In the current context of sustainable development, bio based products have been synthesized and optimization of the process was achieved in order to reduce waste and energy consumption.The key role of the hydrogenoxalate anion was demonstrated in the synthesis of ionic liquids and/or imidazolium salts. Some of them were employed as recyclable catalysts for Fischer e…

Mixotrophy in Pyroleae (Ericaceae) from Estonian boreal forests does not vary with light or tissue age

2017

SPE IPM UB; International audience; In temperate forests, some green plants, namely pyroloids (Pyroleae, Ericaceae) and some orchids, independently evolved a mode of nutrition mixing photosynthates and carbon gained from their mycorrhizal fungi (mixotrophy). Fungal carbon is more enriched in 13C than photosynthates, allowing estimation of the proportion of carbon acquired heterotrophically from fungi in plant biomass. Based on 13C enrichment, mixotrophic orchids have previously been shown to increase shoot autotrophy level over the growth season and with environmental light availability. But little is known about the plasticity of use of photosynthetic versus fungal carbon in pyroloids. Met…

The influence of fermentation conditions on biomass composition during ethanol biosynthesis from cheese whey lactose concentrate by Kluyveromyces mar…

2014

ChemInform Abstract: Organocatalytic Enantioselective Friedel-Crafts Alkylation of 1-Naphthol Derivatives and Activated Phenols with Ethyl Trifluorop…

2016

Financial support from the MINECO [Gobierno de Espana and FEDER (EU)] (CTQ2013-47949-P) and from Generalitat Valenciana (ISIC2012/001) is gratefully acknowledged. M.M.-M. thanks the Universitat de Valencia for a predoctoral grant. C. V. thanks MINECO for JdC contract. Access to NMR and MS facilities from the Servei central de support a la investigacio experimental (SCSIE)-UV is also acknowledged.

Diastereo- and enantioselective synthesis of orthogonally protected 2,4-diaminocyclopentanecarboxylates: a flip from beta-amino- to beta,gamma-diamin…

2007

Conformationally restricted, orthogonally protected 2,4-diaminocarboxylates with a cyclopentane skeleton were efficiently synthesized from beta-lactam 6, the syntheses involving strategies of diastereoselective epoxidation of the beta-lactam and the corresponding monoprotected amino esters with opposite selectivities followed by regioselective opening of the oxirane ring with sodium azide. The enantiomers were also prepared. This new class of compounds can be regarded not only as conformationally constrained beta,gamma-diamino acid derivatives but also as potential functionalized carbocyclic nucleoside precursors.

Changes of 1-Aminocyclopropane-1-Carboxylic Acid Oxidase Activity in Stressed Pinus Sylvestris Needles

2001

Stimulation of ethylene biosynthesis in pine needles by hydrogen peroxide and sodium bisulfite coincided with the activation of ACC oxidase at the level of protein synthesis. Decrease in ethylene production at high concentrations of sodium bisulfite (above 7 mM) was apparently due to inhibition of ACC oxidase activity. Treatment of pine needles with aminotriazole caused an inhibition of both ethylene production and ACC oxidase activity. Both methylviologen and methyl jasmonate stimulated ACC oxidase activity in a concentration-dependent manner with no parallel changes in ethylene production. The presented results suggest that ACC oxidase plays an important role in regulation of ethylene for…

Determination of transport and kinetic properties in self-propagating high-temperature synthesis

2007

International audience; Exothermic reactions in solid powders are analyzed using the usual macroscopic modeling based on the heat transfer equation coupled to an Arrhenius type of dynamics. This problem have important applications in the synthesis of intermetallics and ceramic materials which occur when a high temperature reaction wave propagates throughout the system. Understanding the mechanism of such processes are thus crucial in mastering real laboratory experiments. We first analyze the model, both theoretically and numerically, for a set of representative parameters. We then use traditional data analyses procedures to estimate from the temperature profiles the same set of representat…

Combustion synthesis of MoSi2 and MoSi2–Mo5Si3 composites: Multilayer modeling and control of the microstructure

2010

International audience; In this work, we present a multilayer modeling for the formation of molybdenum silicides in the exothermic reaction between Mo and Si under the influence of a temperature pulse. The heating rate can either be a well-controlled ramp or be generated spontaneously by the propagation of a combustion synthesis front. The model addresses the specific situation above the melting point of silicon and describes the solid–liquid reaction taking place in a single representative particle of molybdenum surrounded by the melt of silicon. We obtain a set of kinetic equations for the propagation of the interfaces between the different layers (Mo/Mo5Si3 and Mo5Si3/MoSi2) in the solid…

Expression patterns of matrix genes during human skeletal development.

1994

Estimating crop primary productivity with Sentinel-2 and Landsat 8 using machine learning methods trained with radiative transfer simulations

2019

Abstract Satellite remote sensing has been widely used in the last decades for agricultural applications, both for assessing vegetation condition and for subsequent yield prediction. Existing remote sensing-based methods to estimate gross primary productivity (GPP), which is an important variable to indicate crop photosynthetic function and stress, typically rely on empirical or semi-empirical approaches, which tend to over-simplify photosynthetic mechanisms. In this work, we take advantage of all parallel developments in mechanistic photosynthesis modeling and satellite data availability for an advanced monitoring of crop productivity. In particular, we combine process-based modeling with …