Field Experience on Corrugated Metal Culverts

The behaviour of buried structures in earth embankments is related to the stiffness properties of the composite system comprising both the buried structure and the surrounding soil taken as a basic structural unit responding to loading imposed on the system. A field experience on corrugated metal culverts equipped with contractable seams has been carried out in order to verify the transfer of load to or away from the buried structure as a result of the difference in stiffness properties of the structure, with its adjacent encompassing material, and the surrounding expanse of soil

Facile access to a heterocyclic, sp3-rich chemical scaffold via a tandem condensation/intramolecular nitrone–alkene [3+2] cycloaddition strategy

A heterocyclic, sp3-rich chemical scaffold was synthesised in just 6 steps via a highly regio- and diastereo-selective tandem nitrone formation/intramolecular nitrone–alkene [3+2] cycloaddition reaction. A library of 543 lead-like compounds based on the scaffold core has been produced

Méthode rapide de mesure de l’activité globale d’un échantillon de produit alimentaire

Legeay G. Méthode rapide de mesure de l’activité globale d’un échantillon de produit alimentaire. In: Bulletin de l'Académie Vétérinaire de France tome 114 n°8, 1961. pp. 327-332

Surface engineering of microfluidic systems for cellular biochips

Times Cited: 1 Griscom, L Legeay, G Le Pioufle, B 3rd IEEE/EMBS Special Topic Conference on Microtechnology in Medicine and Biology May 12-15, 2005 Oahu, HI Ieee, embsInternational audienceIn this paper, we describe a rapid and cost-effective hydrophilic surface modification method for PDMS microsystems that is both durable and biocompatible. The method involves a combination of an oxygen plasma treatment followed by coating the activated surfaces with a hydrophilic and biocompatible polymer. In this case, poly(vinylpyrrolidone) (PVP) is used to increase the surface energy of PDMS microchannels and render them hydrophilic. Contact angle experiments show that the surface of the PDMS remains hydrophilic for an extended period of time under dry conditions. Uses for microfluidic and cell chip applications are demonstrated

New surfaces with hydrophilic/hydrophobic characteristics in relation to (no)bioadhesion

The possibility of biosurfaces with high or low adhesiveness for protein, bacteria or eukaryotic cells is discussed. At the interface surface object/biological milieu, biocompatibility, (no) bioadhesion and (no) biocontamination are shown to be correlated with physico-chemical surface characteristics. First consequence is the (no) possibility of biofilm formation. Substrates with low surface energy could interact only with hydrophobic biomolecules. On substrates with high surface energy, a water monolayer spontaneously formed. Modification of a surface by plasma techniques is a way for engineering biomaterials. Plasma techniques are dry processes and more suitable for biomedical applications. In the field of biomaterial medical devices, in hygienic prevention of nosocomial diseases, in food packaging, the use of substrates with a very hydrophilic character may help to prevent the proliferation of cells and bacteria. Such a technique is so efficient that antibiotic molecules are not necessary. Therefore, surface engineering is a tool for modifying and adapting materials to specific biological applications

Radio frequency plasma treatments on titanium for enhancement of bioactivity.

Item does not contain fulltextTitanium and its alloys, when treated in alkali solutions, are able to form calcium phosphate coatings on their surface after immersion in supersaturated solutions. In this study, the surfaces of titanium alloy discs were modified by an alkali treatment and a radio frequency (RF) plasma procedure (150 W and 13.56 MHz) in N(2), CO(2) or N(2)/O(2) (80/20%) atmospheres. After the alkali treatment, atomic force microscopy showed differences in the surface roughness of the samples. X-ray photoelectron microscopy indicated that the chemical composition of the surfaces changed after the different alkali and RF plasma treatments. The contact angles were also modified by approximately 5 degrees , making the original titanium surface more hydrophilic. Immersion in a supersaturated calcium phosphate solution was used to evaluate the bioactivity of the RF plasma-treated samples in vitro. Alkali-treated samples gave more homogeneous and thick coatings that those without alkali treatment. The use of RF plasma treatments enhanced the bioactivity of the samples, in particular for treatments performed in N(2) or N(2)/O(2) atmospheres. Energy-dispersive X-ray analysis indicated that coatings had Ca/P ratios between the values of octacalcium phosphate and hydroxyapatite. X-ray diffraction confirmed the presence of these two phases in most of the coatings. This study shows that an RF plasma treatment enhanced the bioactivity of titanium surfaces