Redox grafting of diazotated anthraquinone as a means of forming thick conducting organic films

Thick conductive layers containing anthraquinone moieties are covalently immobilized on gold using redox grafting of the diazonium salt of anthraquinone (i.e., 9,10-dioxo-9,10-dihydroanthracene-1-diazonium tetrafluoroborate). This grafting procedure is based on using consecutive voltammetric sweeping and through this exploiting fast electron transfer reactions that are mediated by the anthraquinone redox moieties in the film. The fast film growth, which is followed by infrared reflection absorption spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and coverage calculation, results in a mushroom-like structure. In addition to varying the number of sweeps, layer thickness control can easily be exerted through appropriate choice of the switching potential and sweep rate. It is shown that the grafting of the diazonium salt is essentially a diffusion-controlled process but also that desorption of physisorbed material during the sweeping process is essentially for avoiding blocking of the film due to clogging of the electrolyte channels in the film. In general, sweep rates higher than 0.5 V s(-1) are required if thick, porous, and conducting films should be formed.     

Gigantic exchange enhancement of spin g-factor for two-dimensional electron gas in GaAs

Gigantic, oscillatory values of the spin g-factor for two-dimensional electron gas in GaAs have been measured, using the Shubnikov-deHaas effect in GaAs - Al_0.3Ga_0.7As heterojunctions. The effect has been attributed to the exchange interaction and compared with the theory of Ando and Uemura. The observed g-factor enhancement is, together with the fractional quantum Hall effect, the strongest evidence for the decisive role of many-body interactions in the 2D electron gas.     

Multifunctional Redox Polymers: Electrochrome,Polyelectrolyte, Sensor,Electrode Modifier,Nanoparticle Stabilizer,and Catalyst Template

Simple “click” polycondensation metallopolymers of redox‐robust bis(ethynyl)biferrocene (biFc) and di(azido) poly(ethylene glycol) (PEG400 and PEG1000) were designed for multiple functions including improvement of water solubility and biocompatibility, the introduction of mixed valency and sensing capabilities, and as nanoparticle stabilizers for catalysis.     

Design of In-Line Emulsification Processes for Water-in-Oil Emulsions

The fabrication of water-in-oil emulsions is a process with widespread applications in formulation engineering. The most common process approach is to use a stirred vessel provided with a high speed dispersing impeller or a rotor-stator head and operated in batch or semi-batch mode. The mean drop size and the drop size distribution are usually correlated by the properties of the surfactants and the specific mechanical energy dissipated by the mixer among others. The present paper addresses an application in the oil industry: the large-scale manufacturing of a fine water-in-oil emulsion. Instead of using a tank-based operation, the idea is to create the emulsion in line and operate the process in a continuous mode. Several commercial in-line dispersing technologies are available and the purpose is here to determine the process and dispersing technology parameters that make possible the fabrication of a stable emulsion. Likewise in stirred tank, it is shown that apart from the energy dissipation rate, the kinetics properties of the surfactants and the process configuration also play a major role in obtaining a stable emulsion.     

Continuité lipschitzienne des solutions d'un problème en calcul des variations

In this Note, we describe some recent developments concerning the regularity of the minimizers u of ${\int }_{\Omega }F(\mathrm{?}u)+G(x,u)$, over the functions $u\in W^{1,1}(\Omega )$ that assume given boundary values ? on ?Ω. The classical Hilbert–Haar theory derives regularity of u from an assumption on ?, the well-known bounded slope condition. Instead of this, we impose the less restrictive lower (or upper) bounded slope condition, which is satisfied if ? is the restriction to ?Ω of a convex (or even semiconvex) function. Under this new assumption and some convexity hypotheses on F and Ω, we show that any minimizer u is locally Lipschitz in Ω. In some cases we are also able to assert that u is continuous on $\overline{\Omega }$. To cite this article: P. Bousquet, F. Clarke, C. R. Acad. Sci. Paris, Ser. I 343 (2006).     

Qualitative and quantitative investigation of chromium-polluted soils by laser-induced breakdown spectroscopy combined with neural networks analysis

Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of three chromium-doped soils. Two chemometric techniques, principal components analysis (PCA) and neural networks analysis (NNA), were used to discriminate the soils on the basis of their LIBS spectra. An excellent rate of correct classification was achieved and a better ability of neural networks to cope with real-world, noisy spectra was demonstrated. Neural networks were then used for measuring chromium concentration in one of the soils. We performed a detailed optimization of the inputs of the network so as to improve its predictive performances and we studied the effect of the presence of matrix-specific information in the inputs examined. Finally the inputs of the network—the spectral intensities—were replaced by the line areas. This provided the best results with a prediction accuracy and precision of about 5% in the determination of chromium concentration and a significant reduction of the data, too. Awarded a poster prize on the occasion of the Euro-Mediterranean Symposium on Laser-induced Breakdown Spectroscopy (EMSLIBS 2005), Aachen, Germany, 6–9 September 2005.     

Large Scale Integration of Functional Radio-Frequency Flexible MEMS under Large Mechanical Strain

A versatile industrial recipe of transferring nitride microelectronic components such as micro-electromechanical systems (MEMS) onto flexible and stretchable substrates is demonstrated. This method bypasses difficulties of temperature-related processing, and is applicable to large-scale and mass production. The technological process of fabrication is presented along with its underlying structural and radio-frequency characterizations. In particular, the Raman strain shifts of aluminum nitride (AlN) thin films are determined for uniaxial and biaxial mechanical deformations. The transferring process onto polymer is also demonstrated by an adhesive bonding of AlN-based MEMS onto a 200 mm silicon (Si) wafer. The devices microstructure is assessed using X-ray before and after transferring, as well as their electrical radio-frequency (RF) features when on Si and polymer substrates. Then, RF measurements are also performed on the transferred and flexible devices; some in their relaxed states, and others in an in situ manner under an increasing macroscopic strain. It is shown that bulk acoustic wave resonator MEMS are fully functional even under 12% uniaxial stretching of the substrate.     

Irradiation ageing of CSPE/EPR control command electric cables. Correlation between mechanical properties and oxidation

In this paper, correlations between the elongation at break and the oxidation of chlorosulfonated polyethylene and ethylene propylene rubber (EPR) polymers in instrumentation and control cables irradiated at different dose rates are brought to evidence. During irradiation, the following phenomena are observed: an increase of oxygen consumption, a degradation of the mechanical properties and a reduction of the oxidation induction time (OIT) measured for EPR.

A correlation between the mechanical properties and the OIT of the EPR has only been established in the case of irradiation at low dose rate. This reveals a difference in the oxidative degradation process at low and high dose rates. This study shows the possibility to assess the ageing of electric cables installed inside nuclear power plants by OIT measurements.     

Etude de la stabilite thermique des ethylates alcalins

Résumé La décomposition thermique des éthylates de Li, Na, K, Rb, Cs et de leurs solvates a été étudiée par thermogravimétrie couplée à un dispositif de microsublimation et par analyse thermique différentielle. La réaction de décomposition thermique des éthylates alcalins est complexe et conduit à la formation simultanée d'hydrogène et d'éthylène; les résidus de décomposition ne correspondent à aucun composé défini.

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The thermal dissociation of Li, Na, K, Rb and Cs alcoholates and their respective solvates has been studied by DTA and TG coupled with a gas analysis device. The reaction of decomposition is complex, and hydrogen and ethylene are evolved. The solid residue is a mixture of several compounds.

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Zusammenfassung Die thermische Zersetzung der Äthylate von Li, Na, K, Rb, Cs und ihrer Solvate wurde durch thermogravimetrische Analyse mit einer Mikrosublimierungsvorrichtung gekoppelt, sowie mit der Differentialthermoanalyse untersucht. Die thermische Zersetzungsreaktion der alkalischen Äthylate ist komplex und führt zur simultanen Bildung von Wasserstoff und Äthylen; die Zersetzungsrückstände entsprechen keiner definierten Verbindung.

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Nous tenons à remercier la Société ELF-ERAP à Solaize (Rhône) et plus particulièrement Monsieur Finas qui ont eu l'amabilité de nous fournir un mélange étalon de différents hydrocarbures gazeux.