Easy orientation of diblock copolymers on self-assembled monolayers using UV irradiation

A simple method based on UV/ozone treatment is proposed to control the surface energy of dense grafted silane layers for orientating block copolymer mesophases. Our method allows one to tune the surface energy down to a fraction of a mN/m. We show that related to the surface, perpendicular orientation of a lamellar phase of a PS-PMMA diblock copolymer (neutral surface) is obtained for a critical surface energy of 23.9-25.7 mN/m. Perpendicular cylinders are obtained for 24.6 mN/m and parallel cylinders for 26.8 mN/m.Comment: 3 figures, 1 tabl

Efficient DNA isolation from moroccan arar tree [Tetraclinis articulata (Vahl) Masters] leaves and optimization of the rapd-pcr molecular technique

Efficient DNA isolation from Moroccan Arar tree [Tetraclinis articulata (Vahl) Masters] leaves and optimization of the RAPD-PCR molecular technique. Molecular genetic analysis of Arar tree [Tetraclinis articulata (Vahl) Masters] is often limited by the availability of fresh tissue and an efficient and reliable protocol for high quality genomic DNA extraction. In this study, two DNA extraction protocols were specifically developed for extracting high quality genomic DNA from Arar tree leaves: modified QIAgen DNA Kit and protocol developed by Ouenzar et al. (1998). DNA yield and purity were monitored by gel electrophoresis and by determining absorbance at UV (A260/A280 and A260/A230). Both ratios were between 1.7 and 2.0, indicating that the presence of contaminating metabolites was minimal. The DNA yield obtained ranged between 20 to 40 μg/g of plant materiel. The Ouenzar and collaborators protocol gave higher yield but was more time consuming compared to QIAgen Kit. However, both techniques gave DNA of good quality that is amenable to RAPD-PCR reactions. Additionally, restriction digestion and PCR analyses of the obtained DNA showed its compatibility with downstream applications. Randomly Amplified Polymorphic DNA profiling from the isolated DNA was optimized to produce scorable and clear amplicons. The presented protocols allow easy and high quality DNA isolation for genetic diversity studies within Arar tree

Surface Tension Drives the Orientation of Crystals at the Air−Water Interface

International audienceThe fabrication of oriented crystalline thin films is essential for a range of applications ranging from semiconductors to optical components, sensors, and catalysis. Here we show by depositing micrometric crystal particles on a liquid interface from an aerosol phase that the surface tension of the liquid alone can drive the crystallographic orientation of initially randomly oriented particles. The X-ray diffraction patterns of the particles at the interface are identical to those of a monocrystalline sample cleaved along the {104} (CaCO 3) or {111} (CaF 2) face. We show how this orientation effect can be used to produce thin coatings of oriented crystals on a solid substrate. These results also have important implications for our understanding of heterogeneous crystal growth beneath amphiphile monolayers and for 2D self-assembly processes at the air−liquid interface. T he first crystals to grow from a supersaturated aqueous solution often nucleate at the air−water interface. This can happen for a variety of reasons. When crystallization is induced by cooling of a hot, saturated salt solution, for example, faster cooling at the air−water interface makes the super-saturation highest at this location. CaCO 3 nucleation from hard water occurs first at the interface because gaseous CO 2 resulting from the reaction Ca 2+ + 2 HCO 3

Les démarches de réduction des coûts dans les collectivités territoriales françaises : enjeux et état des lieux

Une étude des démarches d’efficience et de réduction des coûts dans les collectivités territoriales françaises est menée. Elle s’appuie sur une recherche documentaire systématique dans la presse spécialisée (notamment dans La Gazette des Communes) et dans les actes des congrès de l’association des fonctionnaires territoriaux en charge de la question (l’AFIGESE) et sur des entretiens avec quatorze experts menés en deux vagues : en 2012, lors de l’émergence de la problématique, puis en 2015, suite à la diminution des dotations de l’Etat. Il est montré que dans le contexte actuel de crise des finances publiques locales, les actions de restructuration des processus opérationnels dans les services publics de proximité sont pour le moment plus rhétoriques que réelles

Huge Seebeck coefficients in non-aqueous electrolytes

The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making" effects of tetraalkylammonium ions on the structure of alcohols.Comment: Submitted to J. Chem. Phy

l’Intention entrepreneuriale chez les étudiants : Enquête auprès d’un échantillon d’étudiants de l’université d’Oran 2

La création d'entreprise est un acte qui naît au sein d'un processus en construction. En amont de celui-ci, de multiples recherches ont tenté d'expliquer les causes qui amènent les individus à devenir entrepreneur (à l’instar de Kolveried, 1996 ; Autio, Keely&Klofsten, 1997 ; Filion, Heureux, Youaleu et Bellavance, 2002 ; Tounès, 2003 ; Emin, 2006 ; Boissin, Chollet et Emin, 2009). Les étudiants, par le biais de mesures spécifiques telles que les incubateurs universitaires et les pépinières d’entreprises qui proposent des formations à la création d’entreprise, ont été une cible privilégiée du développement de l’intention entrepreneuriale. L’objectif de cet article est de tester un modèle d’intention entrepreneuriale développé chez les étudiants, auprès d’étudiants de l’Université d’Oran 2 en Algérie.Les résultats ont mis en exergue l’existence d’une forte intention entrepreneuriale chez les étudiants malgré que le passage à l’acte (la création d’entreprise ou l’entrepreneuriat en général) reste encore modeste dans notre échantillon d’analyse.Mots-Clés : Entrepreneuriat étudiants, intention entrepreneuriale, modèle de Tounès, étudiants algériens

Éditorial

Ce numéro spécial de la revue eJRIEPS rassemble des contributions issues du symposium intitulé « Comment penser les articulations entre approches didactiques et ergonomiques pour étudier les pratiques d’enseignement et de formation ? » présenté lors des rencontres internationales du Réseau de recherche en éducation et en formation, au CNAM, du 4 au-6 juillet 2017. Il interroge les compatibilités et les complémentarités des approches didactiques et ergonomiques pour étudier les pratiques d’ens..

Monte-Carlo simulations of star-branched polyelectrolyte micelles

The concentration profiles of monomers and counterions in star-branched polyelectrolyte micelles are calculated through Monte-Carlo simulations, using the simplest freely-jointed chain model. We have investigated the onset of different regimes corresponding to the spherical and Manning condensation of counterions as a function of the strength of the Coulomb coupling. The Monte-Carlo results are in fair agreement with the predictions of Self-Consistent-Field analytical models. We have simulated a real system of diblock copolymer micelles of (sodium-polystyrene-sulfonate)(NaPSS)-- (polyethylene-- propylene)(PEP) with f=54 hydrophilic branches of N=251 monomers at room temperature in salt-free solution and compared the calculated form factor with our neutron-scattering data.Comment: 14 pages, 20 figure