Frascati : le rôle du Laboratoire de chimie physique dans les débuts de l’utilisation du rayonnement synchrotron.

Cet article relate comment, à l’aide de l’accélérateur de Frascati, le Laboratoire de chimie physique de Paris a vérifié puis exploité les potentialités nouvelles du rayonnement synchrotron pour la spectroscopie des domaines X mous et X-UV. Il résume aussi les contacts d’Yvette Cauchois, directrice de ce laboratoire, avec les physiciens américains qui venaient de tester cette nouvelle source de rayonnement aux USA, ainsi que les démarches faites auprès des physiciens des hautes énergies d’Orsay pour tenter d’obtenir une ligne de lumière dès la mise au point du premier anneau de collision électrons positrons.This article describes how the Paris laboratory for physical chemistry with the help of the Frascati accelerator first checked and then exploited the new possibilities of synchrotron radiation for the spectroscopy of soft X and X-UV realms. It summarizes also the contacts Yvette Cauchois, the director of the laboratory, made with American physicists, who had recently tested this new source of radiation, as well as the collaboration with the high-energy physicists of Orsay in attempting to achieve a light beam on focusing the first ring of electron-positron collision

The Sciences ACO Light and Matter Museum

International audienceSciences ACO is a non-profit association based in Orsay (France). It manages a Museum of Light and Matter visited by more than 1,000 people each year. In this unique place, scientists and cultural mediators preserve, exhibit and comment on items of the history of science & technology, to pass on the knowledge of this heritage to the audience. Sciences ACO visitors – among them many high school students and teachers – come to learn about the progress of science and the technology evolution over more than four decades. Sciences ACO is more than just a historical museum: it is a driving force for the development for outreach and pedagogical activities on the Paris-Sud University campus and in the neighboring towns. The history, the present activity and the prospects of the Sciences ACO association are presented in this article

Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (mu CT). Experimental results.showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber-the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowed visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars