Scientific Rationale of Saturn's In Situ Exploration

Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustratedby the exploration of Jupiter, where key measurements such as the determination of the noble gases abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. This paper describes the main scienti-c goals to be addressed by the future in situ exploration of Saturn placing the Galileo probe exploration of Jupiter in a broader context and before the future probe exploration of the more remote ice giants. In situ exploration of Saturn's atmosphere addresses two broad themes that are discussedthroughout this paper : rst, the formation history of our solar system and second, the processes at play in planetary atmospheres. In this context, we detail the reasons why measurements of Saturn's bulk elemental and isotopiccomposition would place important constraints on the volatile reservoirs in the protosolar nebula. We also show that the in situ measurement of CO (or any other disequilibrium species that is depleted by reaction with water) in Saturn's upper troposphere may help constraining its bulk OH ratio. We compare predictions of Jupiter and Saturn's bulk compositions from different formation scenarios, and highlight the key measurements required to distinguish competing theories to shed light on giant planet formation as a common process in planetary systems with potential applications to mostextrasolar systems. In situ measurements of Saturn's stratospheric and tropospheric dynamics, chemistry and cloud-forming processes will provide access to phenomena unreachable to remote sensing studies. Dierent mission architectures are envisaged, which would benet from strong international collaborations, all based on an entry probe that would descend through Saturn's stratosphere and troposphere under parachute down to a minimum of 10 bars of atmospheric pressure. We rally discuss the science payload required on a Saturn probe to match the measurement requirements

POLYMORPHISMES BIOCHIMIQUES DE LA POULE DOMESTIQUE. I. — ANALYSE GÉNÉTIQUE DES PROTÉINES DU BLANC D'ŒUF CHEZ DES POULES DE RACES FRANÇAISES ET ÉTRANGÈRES

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Photosynthese et elaboration des reserves des graines chez divers types de soja a croissance indeterminee, semi-indeterminee et determinee

National audienceDevelopment, photosynthesis and storage in the seeds of soybean (Glycine max (L.), Merr.) were studied comparatively in two indeterminate genotypes (« Kingsoy» currently grown in France and « L 65 » nonnodulating), one semi-determinate line (« 59-9-1-2 ») and one determinate genotype (« Hobbit », so-called « semi-dwarf »). Canopy photosynthesis and seed production were not affected by growth type ; the nonnodulating line, with lower N-nutrition and photosynthetic activity, was clearly less productive. Assimilates synthesized during seed filling were not sufficient for seed development, so compounds stored in the shoots during vegetative growth were found to be redistributed. Accordingly, seed proteogenesis made great use of nitrogenous compounds stored in the leaves. On the other hand, lipid synthesis preferentialy used fixed carbon during seed filling. Nitrogen stress of non-nodulating genotype « L 65 » led to higher lipidogenesis and a lower protein content. The seed protein/lipid ratio was more affected by nitrogen nutrition than by growth type.Une étude comparative du développement, de la photosynthèse et de l’élaboration des réserves des graines de soja (Glycine max (L.), Merr.) est réalisée pour deux variétés à croissance indéterminée : « Kingsoy » la plus cultivée en France et « L 65 » lignée non nodulante, une lignée à croissance semi-déterminée « 59-9-1-2 » et une variété de type déterminé, dit demi-nain, « Hobbit ». Le type de croissance n’influe pas sur la photosynthèse du couvert végétal ni sur la production des graines ; la lignée non nodulante est déficiente en N : son activité assimilatrice est plus faible et sa productivité réduite. Les assimilats synthétisés durant la période de remplissage ne suffisent pas à assurer le développement des graines qui nécessite une redistribution des constituants biochimiques de l’appareil végétatif. Ainsi la protéogenèse dans les graines bénéficie largement de la mobilisation de molécules carbonées et azotées préalablement stockées. En revanche, la formation des lipides dépend davantage du carbone fixé pendant la période de remplissage. L’alimentation déficiente en azote de la lignée « L 65 » se traduit par une synthèse lipidique plus importante et une moindre teneur en protéines. Le rapport protéines/lipides des graines apparaît beaucoup plus conditionné par l’alimentation azotée que par le type de croissance

Changes in RuBisCO activity and net photosynthesis under several crop managements applied to sunflower (Helianthus annus L., cv Topflor)

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Influence de l'alimentation en azote sur la participation des feuilles au developpement des graines chez le soja

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ABA content and some key enzyme activities in response to water stress

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Influence de la nutrition azotee sur l'assimilation nette et la formation du rendement du tournesol.

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Variation de la photosynthese nette de la Rubisco et de l'assimilation globale estimee selon l'intensite des pratiques de culture du soja.

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Surface functionalization of plasticized chitosan films through PNIPAM grafting via UV and plasma graft polymerization

International audienceChitosan films were formulated and subsequently given thermosensitive properties by modifying the surfaces. The first step involved the incorporation of poly(ethylene glycol) (PEG) plasticizers at various ratios into the chitosan blends. Tensile tests showed that the molecular weight of the PEG impacted the mechanical properties, while the plasticizing effect was optimal for a PEG content of 20%. The addition of glycerol, in combination with PEG, increased the elongation at break without altering the tensile strength. In order to add thermosensitive properties to the chitosan films, poly(N-isopropylacrylamide) (PNIPAM) was graft polymerized on the surface via two methods: UV irradiation or plasma treatment. The surface modification was evaluated in terms of surface characteristics (XPS, SEM, contact angle) and bulk swelling abilities, with a specific focus on the thermosensitive nature due to the lower critical solution temperature (LCST) transition of the PNIPAM. The two grafting methods implied differences in terms of thermal responsiveness. Indeed, due to the presence of particles on their surfaces, UV grafted samples exhibited higher hydrophilicity and thermosensitivity, whereas their lower content of PNIPAM involved lower swelling thermal dependence. All of these results support the interest in PNIPAM grafted chitosan surfaces for the development of smart biomaterials