A comparative study of Tam3 and Ac transposition in transgenic tobacco and petunia plants

Transposition of the Anthirrinum majus Tam3 element and the Zea mays Ac element has been monitored in petunia and tobacco plants. Plant vectors were constructed with the transposable elements cloned into the leader sequence of a marker gene. Agrobacterium tumefaciens-mediated leaf disc transformation was used to introduce the transposable element constructs into plant cells. In transgenic plants, excision of the transposable element restores gene expression and results in a clearly distinguishable phenotype. Based on restored expression of the hygromycin phosphotransferase II (HPTII) gene, we established that Tam3 excises in 30% of the transformed petunia plants and in 60% of the transformed tobacco plants. Ac excises from the HPTII gene with comparable frequencies (30%) in both plant species. When the β-glucuronidase (GUS) gene was used to detect transposition of Tam3, a significantly lower excision frequency (13%) was found in both plant species. It could be shown that deletion of parts of the transposable elements Tam3 and Ac, removing either one of the terminal inverted repeats (TIR) or part of the presumptive transposase coding region, abolished the excision from the marker genes. This demonstrates that excision of the transposable element Tam3 in heterologous plant species, as documented for the autonomous element Ac, also depends on both properties. Southern blot hybridization shows the expected excision pattern and the reintegration of Tam3 and Ac elements into the genome of tobacco plants.

Spéciation des espèces soufrées dans les générateurs de vapeur des centrales nucléaires à réacteur à eau sous pression

Afin de mieux comprendre les processus de corrosion des tubes en alliage 600 mill annealed des générateurs de vapeur des centrales nucléaires à réacteur à eau sous pression, nous avons étudié le comportement des espèces soufrées en présence d une magnétite synthétique prise pour modèle des dépôts trouvés dans ces générateurs. Les propriétés acide-base de cette magnétite ont été déterminées par zétamétrie et titrage acide-base à 25C, et par titrage de masse entre 25 et 320C. La sorption des sulfates sur la magnétite a été étudiée entre 25 et 275C en fonction du pH et de la concentration en sulfate, avec ou sans hydrogène. Si, globalement, comme prévu pour un anion, la quantité sorbée augmente avec la diminution du pH au dessous du PIE, plusieurs comportements particuliers ont été observés, liés à la stabilité de la magnétite et aux phénomènes d oxydo-réduction. En présence d hydrogène, des espèces réduites apparaissent, dont la troilite (FeS), détectée par spectrométrie de photo-électrons (XPS). Les données thermodynamiques prévoient des réductions même sans présence d hydrogène, mais, en raison de facteurs cinétiques, seule une partie d entre elles sont observées. Les résultats et leur modélisation ont permis d améliorer la compréhension du rôle des espèces soufrées dans les générateurs de vapeur, d affiner le modèle sulfate utilisé jusqu à présent, notamment en introduisant les espèces réduites.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Deposition of hematite particles on polypropylene walls in dynamic conditions

An experimental circulating water loop has been constructed to study the deposition of hematite particles of average diameter 320 nm on polypropylene pipe walls in the ranges pH 4-11, Re 3300-17,700 at 25 degrees C. Real-time turbidimetric measurements were used to measure the deposited concentrations. Results showed that the deposition rate increased when pH decreased and when the flow rate increased. Adhesion was observed even under repulsive electrostatic conditions (pH GT 7), where the surfaces of hematite and polypropylene were both negative, indicating that the kinetic energy of at least a part of the particles Surpassed the electrostatic repulsive potentials. The experimental Curves Were fitted by a model assuming simultaneous adhesion and removal of particles, leading to adhesion and removal rate constants, whose values depend on pH and flow rate. Removal is negligible below pH 9. (c) 2008 Elsevier Inc. All rights reserved

Determination of isoelectric points of metals and metallic alloys by adhesion of latex particles

A set-up and a method were developed to determine the isoelectric point of metals and metallic alloys samples (stainless steels, inconel, zircaloy, aluminum and dural) by measuring the adhesion rate of negative latex particles. The concentration of polystyrene spheres with surface carboxylate groups (initially 0.5-1 mg L(-1)) in contact with metallic samples was measured as a function of pH and time by turbidimetry. The simulation of measurements by a model predicting the sticking coefficient based on DLVO theory was used for the determination of the isoelectric point from experimental results. It was found that the isoelectric points of aluminum (8.7) and dural (9.1), treated by boiling water, are close to those of hydrated aluminum oxides powders. For stainless steels, inconel and zircaloy, the values of isoelectric points were found to be between 2.4 and 3.0, far below the isoelectric points measured for metallic oxides constituting the alloy surface layer. This difference was explained by two different charging mechanisms: (1) deprotonation of hydroxyl groups on the surface of the metal oxide in suspension or as a thick layer. (2) adsorption of hydroxide ions on a metal surface covered by a thin oxide layer, as observed on hydrophobic surfaces. (C) 2009 Elsevier Inc. All rights reserved

Ateliers métallurgiques dans l'habitat protohistorique du Fort-Harrouard

Mohen Jean-Pierre, Aufaure Cécile, Bouet Béatrice, Collin Véronique, Courty Marie-Agnès, Eluère Christiane, Maillard Catherine, Marguerie Dominique, Menu Michel, Queixalos I., Robbiola Luc, Verney Antoine, Walter Philippe. Ateliers métallurgiques dans l'habitat protohistorique du Fort-Harrouard. In: Bulletin de la Société préhistorique française, tome 86, n°10-12, 1989. Du terrain au laboratoire : Pour un meilleur dialogue en archéologie. pp. 404-408

An inverse gas chromatography study of the adsorption of organics on nickel- and copper-hexacyanoferrates at zero surface coverage

The surface properties of Ni and Cu hexacyanoferrates were investigated by the inverse gas chromatography method. Retentions of 10 organic compounds were measured at zero surface coverage in the temperature range 80 to 95 C. The gas/solid partition coefficients and the related thermodynamic data of adsorption (standard free energy change, standard state enthalpies, and entropy changes) also at zero surface coverage were determined. The dispersive component of free surface energy of both hexacyanoferrates, at investigated temperatures, was calculated. The surface acid/base properties were also evaluated using polar adsorbates and the results obtained indicate that nickel hexacyanoferrate is more acidic than copper hexacyanoferrate