Synthesis of geopolymer emulsions

The understanding of emulsion geopolymer synthesis is a major issue for several industrial applications such as the formation of hierarchically porous material for filtration, lightweight materials for civil engineering or even the conditioning of radioactive mineral oil. Emulsion stability (irreversible coarsening, creaming…) are mainly controlled by the interfacial properties (surface tension and nature of the surfactant) and the viscosity ratio between the dispersed (hd) and the continuous phase (hc). The aim of this paper is thus to study model emulsions (composed of hexadecane (C16) as dispersed phase and metakaolin based geopolymer as continuous phase) with the highest volume fraction of C16 as possible. Surfactant was added to the mixture to stabilize the C16 droplets and geopolymer emulsion was synthesis under shear stirring. The influence of the viscosity of the geopolymer paste controlled by the water content was studied and results show that emulsions are unstable for a viscosity ratio hd/hc lower than 0.01. Up to 70% in volume of C16 was incorporated within the geopolymer and hierarchical porous network was thus obtained. Indeed after removal the C16 phase, the porous network was characterized and a specific surface area of 90 m²/g, a mean mesopore diameter of 19 nm, a macropore size distribution ranged between 10-200 µm (fig 1.) and a compression strength of around 0.5 MPa were obtained. Please click Additional Files below to see the full abstract

Contrasting Population Structures of Two Vectors of African Trypanosomoses in Burkina Faso: Consequences for Control

Tsetse flies are insects that transmit trypanosomes to humans (sleeping sickness) and animals (nagana). Controlling these vectors is a very efficient way to control these diseases. In Burkina Faso, a tsetse eradication campaign is presently targeting the northern part of the Mouhoun River Basin. To attain this objective, the approach has to be area-wide, i.e. the control effort targets an entire pest population within a circumscribed area. To assess the level of this isolation, we studied the genetic structure of Glossina palpalis gambiensis and Glossina tachinoides populations in the target area and in the adjacent river basins of the Comoé, the Niger and the Sissili River Basins. Our results suggest an absence of strong genetic isolation of the target populations. We therefore recommend establishing permanent buffer zones between the Mouhoun and the other river basin(s) to prevent reinvasion. This kind of study may be extended to other areas on other tsetse species

Rapid response to the M_w 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to large damages it produced in several villages. InSAR interferograms indicated a shallow rupture about 4 km long reaching the surface and the reactivation of the ancient NE-SW La Rouviere normal fault in reverse faulting in agreement with the present-day E-W compressional tectonics. The peculiarity of this earthquake together with a poor coverage of the epicentral region by permanent seismological and geodetic stations triggered the mobilisation of the French post-seismic unit and the broad French scientific community from various institutions, with the deployment of geophysical instruments (seismological and geodesic stations), geological field surveys, and field evaluation of the intensity of the earthquake. Within 7 days after the mainshock, 47 seismological stations were deployed in the epicentral area to improve the Le Teil aftershocks locations relative to the French permanent seismological network (RESIF), monitor the temporal and spatial evolution of microearthquakes close to the fault plane and temporal evolution of the seismic response of 3 damaged historical buildings, and to study suspected site effects and their influence in the distribution of seismic damage. This seismological dataset, completed by data owned by different institutions, was integrated in a homogeneous archive and distributed through FDSN web services by the RESIF data center. This dataset, together with observations of surface rupture evidences, geologic, geodetic and satellite data, will help to unravel the causes and rupture mechanism of this earthquake, and contribute to account in seismic hazard assessment for earthquakes along the major regional Cévenne fault system in a context of present-day compressional tectonics

Solubilisation d'une huile polaire utilisée dans l'industrie nucléaire par des solutions de copolymères amphiphiles triblocs (Relation comportement-structure par résonnance magnétique nucléaire du proton et diffusion de neutrons aux petits angles)

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Monolithic zirconia foams synthesis from emulsion stabilized by colloidal clusters

International audienc

Stable uranium sols as precursors for the elaboration of nanostructured nc-UO 2 materials

International audienc

Nanoparticules à structure coeur en analogue de bleu de Prusse-coquille, leur procédé de préparation, matériaux les comprenant, et procédé d'extraction de cations métalliques

Nanoparticules à structure cœur-coquille, dans lesquelles : - le cœur de chacune desdites nanoparticules est constitué par une nanoparticule en un hexacyanométallate ou octacyanométallate de métal, répondant à la formule [Alk+ x]Mn+ y[M'(CN)m]t z-, où Alk+ est un cation monovalent choisi parmi les cations de métaux alcalins et le cation ammonium NH4 +, x est égal à 0, 1 ou 2, M est un métal de transition, n est égal à 2 ou 3, y est égal à 1, 2 ou 3, M' est un métal de transition, m est égal à 6 ou 8, z est égal à 3 ou 4, et t est égal à 1 ou 2; - la coquille desdites nanoparticules, qui entoure le cœur, est en au moins un oxyde inorganique poreux. Procédé de préparation desdites nanoparticules à structure cœur-coquille. Matériau échangeur de cations métalliques comprenant lesdites nanoparticules à structure cœur-coquille. Procédé pour extraire au moins un cation métallique à partir d'un milieu liquide le contenant, dans lequel on met en contact ledit milieu liquide avec les lesdites nanoparticules à structure-cœur coquille et/ou ledit matériau échangeur de cations métalliques

High-internal phase emulsions stabilized by colloidal Zr-based solid clusters

International audienc

Simultaneous lanthanides and surfactants micelles removal from aqueous outflows by complexation and sol–gel chemistry

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