Restitution de la température de la mer à partir des données du satellite NOAA/AVHRR

ABSTRACT This paper reviews first the basic problems raised by the Sea Surface Temperature (SST) restitution from A VHRR data, and the solutions adopted at CMS. In particular some results concerning the split window lagorithm errors at large satellite zenith angle will be discussed. Its lain topic concerns however the techniques Used in the operational small scale SST restitution at CMS. The objective of this activity is to provide the French Navy, the océanographie campaigns and some fishing activities with real time or climatological concerning the sea surface temperatures over the European seas. Six zones (2 000 * 2 000 km) have been defined inside the CMS acquisition circle : North Sea, Biscay, Canary Islands, Western Mediterranean, Eastern Mediterranean, Norwegian Sea. After preprocessing on the main computer, each zone (corresponding after sampling and mapping onto a stereopolar grid to a 1 024 * 1 024 pixel image) is analysed, every day, on the image processing system. Various studies or products are based on this processing suite, ranging from daily, weekly (etc.) charts to the making of an SST Atlas over Europe.RÉSUMÉ Ce texte passe d'abord en revue les problèmes de base posés par la restitution de la Température de Surface de la Mer (TSM) à partir des données de l'Advanced Very High Resolution Radiometer (AVHRR) embarqué sur les satellites polaires de la National Oceanic and Atmospheric Administration (NOAA), et les solutions adaptées au CMS. On présentera en particulier la dernière version de l'algorithme de calcul de température de surface tenant compte de l'angle d'incidence de la visée satellitaire. Il aborde ensuite les aspects techniques de la restitution opérationnelle des structures thermiques de la surface des mers européennes à l'échelle fine. Six zones (2 000 * 2 000 km) ont été définies à l'intérieur du cercle d'acquisition du CMS : mer du Nord, golfe de Gascogne, Canaries, Méditerranée occidentale, Méditerranée orientale, mer de Norvège. Après prétraitement sur calculateur principal, chaque zone (correspondant après échantillonage et mise en projection stéréopolaire à une image 1 024 * 1 024) est analysée quotidiennement sur un système interactif de traitement d'image. Divers études et produits sont basés sur cette chaîne opérationnelle, depuis les cartes quotidiennes, hebdomadaires, etc., jusqu'à réalisation d'un Atlas de TSM sur l'Europe.Antoine Jean-Yves, Derrien M, Gaillard O, Le Borgne P, Le Goas C, Marsouin A. Restitution de la température de la mer à partir des données du satellite NOAA/AVHRR. In: Norois, n°155, Juillet-Septembre 1992. pp. 297-304

(In)stability of ligands at the surface of inorganic nanoparticles : a forgotten question in nanomedicine?

Multiple inorganic nanoparticles (NPs) are currently being developed for nanomedicine. Various core materials and shapes are explored, but they all display a common hybrid structure, with organic ligands on their surface. These ligands play a key role in the NP colloidal stability and surface properties, and therefore strongly impact the biological fate of the NPs. However, ligands may be subject to reorganization, degradation, desorption, and exchange, both during their shelf-life and upon exposure to a biological environment. The question of ligand (in)stability at the surface of inorganic NPs has been little addressed in the literature. The goal of this review is to provide a portrait of this critical phenomenon. We identify and review here the different mechanisms likely to promote ligand instability and discuss the resulting biological fate of ligands. This review is aimed to provide a better understanding of these phenomena and to help researchers to design NP-based medicines with better clinical efficacy and translation ability

Irradiation Effects on Polymer-Grafted Gold Nanoparticles for Cancer Therapy

International audienceIn the context of cancer treatment, gold nanoparticles (AuNPs) are considered as very promising radiosensitizers. Here, well-defined polymer-grafted AuNPs were synthesized and studied under gamma irradiation to better understand the involved radiosensitizing mechanisms. First, various water-soluble and well-defined thiol-functionalized homopolymers and copolymers were obtained through Atom Transfer Radical Polymerization. They were then used as ligands in the one-step synthesis of AuNPs, resulting in stable hybrid metal-polymer nanoparticles. Second, these nano-objects were irradiated in solution by gamma rays at different doses. Structures were fully characterized through SEC, SAXS and SANS measurements, prior and after irradiation. We were thus able to quantify and to localize radiation impacts onto the grafted polymers, revealing the production sites of reactive species around AuNPs. Both external and near-surface scissions were observed. Interestingly, the ratio between these two effects was found to vary according to the nature of polymer ligands. Medium-range and long-distance dose enhancements could not be identified from the calculated scission yields, but several mechanisms were considered to explain high yields found for near-surface scissions. Then, cytotoxicity was shown to be equivalent for both non-irradiated and irradiated polymer-grafted NPs, suggesting that released polymer fragments were non-toxic. Finally, the potential to add bioactive molecules such as anticancer drugs has been explored by grafting doxorubicin (DOX) onto the polymer corona. This may lead to nano-objects combining both radiosensitization and chemotherapy effects. This work is the first one to study in details the impact of radiation on radiosensitizing nano-objects combining physical, chemical and biological analyses