Aqueous dispersions of silane-functionalized laponite clay platelets. A first step towards the elaboration of water-based polymer/clay nanocomposites

International audienc

STRUCTURAL EFFECTS IN THE ELECTROLYTES GLASS (LiC1) xH2O AND THE NUCLEATION OF METASTABLE PHASES

L'intérêt des électrolytes aqueux pour la compréhension de l'état vitreux est montré par la diffusion ou la diffraction de neutrons et par D.S.C. Sur deux gammes de compositions, le verre formé ne cristallise pas et un verre avec deux Tg différentes est obtenu. L'effet endothermique observé par D.S.C. pendant Tg, est attribué à un réarrangement du verre. L'effet thermique, se produisant dans le liquide très au-dessus de Tg, est probablement dû au réarrangement des molécules d'eau.The interest of aqueous electrolytes for the understanding of the glassy state is shown by neutron scattering or neutron diffraction and Differential Scanning Calorimetry (D.S.C.). In two ranges of composition the formed glass does not crystallize, and a glass with two different Tg is shown. The overshot as observed by D.S.C. during Tg is attributed to a reordering of the glass. The thermal effect occuring in the liquid well above Tg is probably due to a rearrangement of the water molecules

Thermal characteristics of crude oils treated with rheology modifiers

Thermal characteristics of eight crude oils and their treatment with additives were studied by differential scanning calorimetry (DSC), thermomicroscopy, viscometer and pour point tester. Different additives were found as more effective for different type of crude oils depending on the wax content. Crude oils showed a reduced pour point after treatment with additives. Effects of different additives were also discussed by analysing the DSC curves and thermomicroscopy result

Devenir de polluants organiques dans les sols Extraction et dosage des composes organiques halogenes volatils

SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3406) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Characterisation of a haemoglobin protease secreted by pathogenic Escherichia coli.

Many pathogenic bacteria can use heme compounds as a source of iron. Pathogenic Escherichia coli strains are capable of using hemoglobin as an iron source. However, the mechanism of heme acquisition from hemoglobin is not understood for this microorganism. We present the first molecular characterization of a hemoglobin protease (Hbp) from a human pathogenic E. coli strain. The enzyme also appeared to be a heme-binding protein. Affinity purification of this bifunctional protein enabled us to identify the extracellular gene product, and to clone and analyze its gene. A purification procedure developed for Hbp allowed us to perform functional studies. The protein interacted with hemoglobin, degraded it and subsequently bound the released heme. These results suggest that the protein is involved in heme acquisition by this human pathogen. Hbp belongs to the so-called IgA1 protease-like proteins, as indicated by the kinetics of its membrane transfer and DNA sequence similarity. The gene of this protein apr pears to be located on the large pCoIV-K30 episome, that only has been isolated from human and animal pathogens. All these characteristics indicate that Hbp may be an important violence factor that may play a significant role in the pathogenesis of E. coli infections