Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables

Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by Eumetsat onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfill these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interferences between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential for strongly benefiting the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative

Synthèse d'oligosaccharides de chondroïtines et de sulfates de chondroïtines biotinylés pour l'étude de la biosynthèse des protéoglycanes du cartilage

L arthrose est la plus fréquente des maladies articulaires pour laquelle aucun traitement efficace n est aujourd hui disponible. Elle est caractérisée par une destruction du cartilage et de ses composants, dont font partie les protéoglycanes. Les principaux protéoglycanes cartilagineux sont les sulfates de chondroïtines, qui sont de longs polysaccharides linéaires hétérogènes composés d unités disaccharidiques répétitives constituées d un acide-D-glucuronique et d une N-acétyl-D-galactosamine. Dans le but d étudier la biosynthèse de ces composés et ainsi de mieux comprendre le mécanisme d action des enzymes qui y sont impliquées, la synthèse chimique d oligosaccharides de chondroïtines et de sulfates de chondroïtines biotinylés a été réalisée. Grâce à une méthodologie efficace et innovante basée sur une hydrolyse acide d un polymère de sulfates de chondroïtines, des intermédiaires clés ont rapidement été obtenus. Une stratégie d élongation les utilisant a ensuite été appliquée pour conduire à une première famille de sept oligosaccharides non sulfatés (du disaccharide à l octasaccharide). Deux nouvelles familles d oligosaccharides de sulfates de chondroïtines A et C, sulfatés de façon homogène ont été préparées, à partir d un précurseur commun par stratégie divergente. Pour la première fois, deux oligosaccharides de sulfate de chondroïtine A, présentant une sulfatation hétérogène, ont également été synthétisés. Ces travaux ont mené à la préparation de treize oligosaccharides biotinylés finaux.Osteoarthritis is the most frequent articular disease but until now no treatment exists. It is characterized by a destruction of cartilage and its components as proteoglycans. Major cartilage s proteoglycans are chondroitin sulfate, which are linear and heterogeneous polysaccharides composed of disaccharidic repeating units constituted of a D-glucuronic acid and an N-acetyl-D-galactosamine. In order to study biosynthesis of those compounds and so to better understand working mechanism of the implicated enzymes, chemical syntheses of biotinylated chondroitin and chondroitin sulfate oligomers have been achieved. Thanks to an efficient hydrolysis of a starting chondroitin sulfate polymer, key building blocks were quickly obtained. An elongation strategy using them has been then applied to give a first family of seven non sulfated oligosaccharides (from disaccharide to octasaccharide). Two new families of chondroitin sulfate A and C oligosaccharides, with homogeneous sulfation have been prepared from a common precursor by divergent strategy. For the first time, two chondroitin sulfate A oligosaccharides with an heterogeneous sulfation have been synthetized. This work has led to thirteen final biotinylated oligosaccharides.ORLEANS-SCD-Bib. electronique (452349901) / SudocSudocFranceF

Synthèse d'oligosaccharides de chondroitines sulfate D

ORLEANS-BU Sciences (452342104) / SudocSudocFranceF

Synthèse de fragments de dermatane sulfate

ORLEANS-BU Sciences (452342104) / SudocSudocFranceF

Isomer separation and effect of the polymerization degree on the gas-phase structure of chondroitine sulfate oligosaccharides analyzed by ion mobility-tandem mass spectrometry

International audienc

Matrix-assisted laser desorption/ionization mass spectrometric analysis of polysulfated-derived oligosaccharides using pyrenemethylguanidine.

International audienc

Discrimination of sulfated isomers of chondroitin sulfate disaccharides by HILIC-MS

International audienceChondroitin sulfate (CS) glycosaminoglycans are biologically active sulfated polysaccharides that pose an analytical challenge for their structural analysis and functional evaluation. In this study, we developed a hydrophilic interaction liquid chromatography separation method and its on-line coupling to mass spectrometry (MS) allowing efficient differentiation and sensitive detection of mono-, di-, and trisulfated CS disaccharides and their positional isomers, without requiring prior derivatization. The composition of the mobile phase in terms of pH and concentration showed great influence on the chromatographic separation and was varied to allow the distinction of each CS without signal overlap for a total analysis time of 25 min. This methodology was applied to determine the disaccharide composition of biological reaction media resulting from various enzymatic transformations of CS, such as enzymatic desulfation of CS disaccharides by a CS 4-O-endosulfatase, and depolymerization of the CS endocan by chondroitinase lyase ABC