Relaxation dynamics in covalently bonded organic monolayers on silicon

We study the dynamic electrical response of a silicon-molecular monolayer-metal junctions and we observe two contributions in the admittance spectroscopy data. These contributions are related to dipolar relaxation and molecular organization in the monolayer in one hand, and the presence of defects at the silicon/molecule interface in the other hand. We propose a small signal equivalent circuit suitable for the simulations of these molecular devices in commercial device simulators. Our results concern monolayers of alkyl chains considered as a model system but can be extended to other molecular monolayers. These results open door to a better control and optimization of molecular devices.Comment: 1 pdf file including text, figures and tables. Phys. Rev. B, in pres

Evaluation of a gate capacitance in the sub-aF range for a chemical field-effect transistor with a silicon nanowire channel

An evaluation of the gate capacitance of a field-effect transitor (FET) whose channel length and width are several ten nanometer, is a key point for sensors applications. However, experimental and precise evaluation of capacitance in the aF range or less has been extremely difficult. Here, we report an extraction of the capacitance down to 0.55 aF for a silicon FET with a nanoscale wire channel whose width and length are 15 and 50 nm, respectively. The extraction can be achieved by using a combination of four kinds of measurements: current characteristics modulated by double gates, random-telegraph-signal noise induced by trapping and detrapping of a single electron, dielectric polarization noise, and current characteristics showing Coulomb blockade at low temperature. The extraction of such a small gate capacitance enables us to evaluate electron mobility in a nanoscale wire using a classical model of current characteristics of a FET.Comment: To be published in IEEE Trans. Nanotechno

Global Optimization of H ∞ problems: Application to robust control synthesis under structural constraints

International audienceIn this paper, a new technique to compute a synthesis structured Robust Control Law is developed. This technique is based on global optimization methods using a Branch-and-Bound algorithm. The original problem is reformulated as a min/max problem with non-convex constraint. Our approach uses interval arithmetic to compute bounds and accelerate the convergence

Specifying the behavior of graphical objects using Esterel

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Etude de la synthèse du resvératrol et de ses dérivés (viniférines) par des suspensions de cellules de vigne et optimisation de la production en bioréacteur

Le travail effectué au cours de cette thèse a permis une avancée importante dans la connaissance de l élicitation des cellules de vigne. Nous avons étudié les effets de deux éliciteurs, le méthyljasmonate et la méthyl-b-cyclodextrine, employés seuls et en élicitation croisée sur des suspensions de cellules de vigne (porte-greffe 41B et Vitis labrusca), pour la production de stilbènes (resvératrol et viniférines). Ceci a permis d atteindre des concentrations de resvératrol très élevées pour un métabolite secondaire et les relations entre la concentration d éliciteur, la biomasse à l inoculum et la durée de l élicitation ont été étudiées. D autre part, le travail a également porté sur le changement d échelle quant à la culture cellulaire et son élicitation et sur le suivi de plusieurs phénomènes et paramètres (croissance cellulaire, consommation des sucres, production du resvératrol, suivi du taux d oxygène dissous et du pH). Des essais en bioréacteur clos de 5L ont ainsi abouti à une production significative de resvératrol à cette échelle et ont permis l élaboration de modèles cinétiques rendant compte de la croissance de la biomasse et de la production du resvératrol. Un autre aspect de l étude s est intéressé à la localisation intracellulaire de la synthèse du resvératrol. Les résultats obtenus par microscopie confocale ont confirmé que le resvératrol s accumulait majoritairement dans la paroi de la cellule et dans des vésicules cytoplasmiques (organites sphériques présents à proximité de la paroi), avant d être excrété dans le milieu de culture. Enfin, une démarche a été initiée en vue de la production d autres métabolites à partir du resvératrol notamment l -viniférine.The work presented here addressed two main subjects, namely that of grapevine cells elicitation for the production of stilbenes (resveratrol and viniferins) and the scale up of such culture in bioreactors. Shake-flask cultures of grapevine (rootstock 41B and Vitis labrusca) were elicited with methyl jasmonate or methyl-b-cyclodextrin, alone or in combination. This resulted in a significant accumulation of resveratrol in the medium. The relationship between the production of resveratrol and factors such as the elicitor concentration, inoculation rate and the duration of elicitation phase were studied. The second part of this work was concerned with scale up of the culture from shake-flask to 5 L bioreactor. Several parameters were monitored such as cell growth, sugars consumption, resveratrol production, dissolved oxygen concentration and pH. Kinetic models explaining growth and resveratrol production were developed using the results from three bioreactor batches. Preliminary work was performed to initiate the study of metabolites related to resveratrol such as -viniferin. The study also completed previous work that looked at the localisation of resveratrol synthesis within the cells using confocal microscopy. The results confirmed that resveratrol was accumulated mainly in the cell wall and in the cytoplasmic vesicles before being excreted/secreted into the culture medium.CHATENAY MALABRY-Ecole centrale (920192301) / SudocSudocFranceF

L'éducation à la santé : analyse comparative des manuels scolaires de biologie de 3 pays méditerranéens

International audienceCe travail présente une analyse comparative de manuels scolaires de trois pays méditerranéens (France, Liban et Maroc) en utilisant la même grille spécifique d'analyse. Nous travaillons principalement dans le domaine de la biologie et de la santé. Notre point de vue est résolument didactique, c'est à dire que nos analyses (et donc nos instruments) sont centrés sur des contenus et objectifs relatifs à un enseignement disciplinaire et à un thème précis au sein de cette discipline, celui de l'éducation à la santé et de la prévention. Quelle est la nature des images pour l'éducation à la santé ? Quel modèle d'éducation à la santé et de prévention est privilégié dans ces manuels? Quels sont les styles pédagogiques utilisés ? Telles sont les trois questions qui sont au centre des enjeux de la promotion et de l'éducation à la santé à l'école et auxquelles nos analyses essaient d'apporter une réponse

A simple applicative language: Mini-ML

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Flagellin concentrations in expectorations from cystic fibrosis patients.

International audienceBACKGROUND: The aim was to measure flagellin concentrations in the expectorations of CF patients and to examine whether there are correlations with the level of respiratory insufficiency and inflammation. METHODS: Sputum samples from 31 adult patients chronically colonized with P. aeruginosa were collected and analysed for their content of flagellin and IL-8. Clinical data were extracted from patient files. RESULTS: Regardless of whether patients are colonized with mucoid strains or not, they carry clones of P. aeruginosa that express flagellin. While flagellin was present in airways of all of our CF patients, it is difficult to ascertain its contribution to inflammation (IL-8) and lung function deterioration. CONCLUSIONS: This is the first demonstration that flagellin is present in the sputum of patients. Thus, attempts to down regulate inflammation by the use of TLR5 (flagellin receptor) antagonists remain a possibility. However, this result needs to be extended to a larger number of patients to validate it for future research on this subject

Natural semantics on the computer

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The Sophtalk reference manual

This is the reference manual for the LeLisp implementation of the Sophtalk system. Sophtalk is a set of tools that enable one to program the interaction between objects following an event model of communication. System objects, called stnodes emit messages when significant events occur such as the termination of a computation a request for a service from another object, error conditions, etc. Messages circulate asynchronously in a network of stnodes. An stnode's type determines which messages it will receive, upon reception an action corresponding to the message and stnode instance is triggered. Messages may also circulate between processes. The manual describes the three modules of Sophtalk : stnode, a multicast communication mechanism : stio an extension of the standard LeLisp asynchronous and synchronous i/o mechanisms : and stservice, which offers interprocess communication at the shell and LeLisp levels