Termómetros fotoluminescentes baseados em lantanossilicatos

The hydrothermal synthesis and structural characterization of lanthanide silicates NaLnSiO4, Ln= Gd3+, Eu3+, Tb3+, Er3+ and Yb3+ are reported. The crystal phase purity of these solid was analysed by powder X-ray diffraction and further characterized by scanning electron microscopy, 29Si MAS NMR, Infra-Red, Raman and photoluminescence spectroscopy. After having determined the best synthesis parameters to obtain the compounds, the suitability of the compounds NaGd1-x-yEuxTbySiO4 and Na[(Gd0.85Yb0.10Er0.05)SiO4 to act as ratiometric photoluminescent thermometers was assessed (Eu3+ and Tb3+ are visible emitters, and Er3+ and Yb3+ infra-red emitters). The Tb3+ to Eu3+ and Yb3+ to Er3+ energy transfers were detected, leading to a temperature dependence of the emission ratio between the Tb3+ 5D4→7F5-0 and Eu3+ 5D0→7F0-4 transitions for NaGd1-x-yEuxTbySiO4 and between Yb3+ 2F5/2→2F7/2 and Er3+ 4I13/2→4I15/2 transitions for Na[(Gd0.85Yb0.10Er0.05)SiO4. This ratio allows the determining the sensitivity of the compounds to act as thermometers. At cryogenic temperatures, the sensitivity obtained depends on the composition parameters x and y for Na[(Gd0.85Yb0.10Er0.05)SiO4. The infrared ratiometric luminescent thermometer NaGd1-x-yErxYbySiO4 presents the best performance in terms of sensitivityA síntese hidrotérmica e a caracterização estrutural de silicatos de lantanídeo, NaLnSiO4 (Ln = Gd3+, Eu3+, Tb3+, Y3+, Er3+ e Yb3+), são relatadas. A pureza cristalina destes sólidos foi analisada por difracção de raios-X de pós e adicionalmente caracterizados por microscopia electrónica de varrimento, RNM de 29Si MAS e espectroscopias de infravermelho, Raman e de fotoluminescência. Após a determinação dos melhores parâmetros de síntese para a obtenção dos compostos, avaliou-se a adequabilidade dos compostos NaGd1-x-yEuxTbySiO4 e Na[(Gd0.85Yb0.10Er0.05)SiO4 para actuarem como termómetros raciométricos fotoluminescentes (Eu3+ e Tb3+ são emissores visíveis, e Er3+ e Yb3+ são emissores infravermelhos). As transferências de energia entre do Tb3+ para o Eu3+ e do Yb3+ para o Er3+ foram detectadas, as quais levam a uma dependência com a temperatura dos rácios entre as transições 5D4→7F2 (Tb3+) e 5D0→7F2 (Eu3+) para NaGd1-x-yEuxTbySiO4 e entre as transições 2F5/2→2F7/2 (Yb3+) e 4I13/2→4I15/2 (Er3+) para Na[(Gd0.85Yb0.10Er0.05)SiO4. Esses rácios permitem determinar a sensibilidade dos compostos para actuar como termómetros. A temperaturas criogénicas, a sensibilidade obtida depende dos parâmetros de composição x e y para NaGd1-x-yEuxTbySiO4. O termómetro raciométrico luminescente no infravermelho, Na[(Gd0.85Yb0.10Er0.05)SiO4, apresenta o melhor desempenho em termos de sensibilidadeMestrado em Químic

Synthesis, Characterization, and Functionalization of 2-Vinyl-4,4-Dimethylazlactone Brushes to Create Bio-Inspired Materials

Functional materials built from polymer scaffolds inspire many potential uses, including as biomaterial surfaces or sensors. In situ functionalization using well-defined polymer “brushes” made by tethering polymer chains to a surface by one of their ends is explored. Specifically, poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) chains, which contain a reactive azlactone ring at each repeat unit, are tethered to a surface to create brushes and these films are functionalized using a variety of small molecules, primarily amines or peptides. Relationships between polymer brush thickness, size of the functionalizing molecule, solution concentration, reaction time, and extent of functionalization were determined through measurements of brush thickness and PVDMA characterizations. These synthesis-structure-property relationships help inform decisions about how to create functional polymer scaffolds with desired properties

Les plans locaux d’urbanisme intercommunaux

Editorial de Daniel Delaveau, Président de l’Assemblée des Communautés de France : L’urbanisme fait partie des sujets sur lesquels notre sensibilité d’élu local est vive ; c’est une compétence symbolique à laquelle nous sommes, je crois légitimement, très attachés. Nos décisions en matière de planification urbaine s’inscrivent durablement dans nos territoires, elles sont des marqueurs importants de nos mandats locaux. Il nous faut cependant donner un sens nouveau à cette planification urbaine au regard des évolutions très profondes qu’ont connues nos territoires ces dernières décennies. Un partage des réflexions et décisions dans le cadre collégial qu’offrent nos communautés peut indéniablement contribuer à relever ce défi. C’est une conviction désormais ancienne des instances nationales de l’AdCF qui ont souhaité poursuivre leur programme d’étude et d’observation engagé sur le sujet de l’urbanisme intercommunal dès 2006. L’enjeu est d’adapter la planification urbaine à l’échelle du fonctionnement de nos territoires. Nous observons, d’ailleurs souvent en tant que maires, que nos limites municipales sont dépassées par l’essentiel de nos enjeux. En milieu rural comme dans les espaces urbains ou périurbains, nos problématiques de déplacement, de paysage, d’habitat, de commerce, d’agriculture, de biodiversité ou encore d’environnement ne peuvent plus être traitées convenablement à notre seule échelle municipale tant elles la transgressent. Seul document opposable aux tiers, le PLU revêt une dimension stratégique majeure dans la gestion des sols ; son évolution apparaît indispensable pour la cohérence de nos politiques publiques. Dans le cadre des travaux préparatoires au Grenelle de l’Environnement, dans lesquels elle s’est beaucoup investie, l’AdCF a milité pour une élaboration intercommunale du PLU dans une logique de coproduction et de coresponsabilité entre communes. Cette logique du « faire ensemble » pour gagner collectivement en compétence continue d’animer l’ensemble de ses travaux. Diverses dispositions du Code de l’urbanisme relatives au PLUi, soutenues voire suggérées par notre association, illustrent cette volonté de respect des avis et des ambitions municipales. Mais il convient naturellement de dépasser la simple addition des volontés des communes membres ; l’enjeu est de construire un plan local d’urbanisme communautaire qui assure une mise en oeuvre des orientations stratégiques des communautés. La présente étude atteste de la réussite de nombreuses communautés compétentes en matière de PLU. Elle souligne également les difficultés que peuvent rencontrer ces 200 communautés de communes, d’agglomération ou urbaines. Par le recueil de témoignages, elle pointe les spécificités du PLUi notamment sur le champ de la gouvernance politique. Elle complète en outre les notes à caractère plus juridique ou technique régulièrement produites par l’AdCF. L’AdCF joue un rôle actif dans l’animation du « club PLUi » initié et piloté par les services du ministère de l’Égalité des territoires et du Logement. Je souhaite que cette étude alimente ses travaux et, sans attendre les très probables débats parlementaires sur un transfert plus systématique du PLU, qu’elle contribue à éclairer les nombreuses réflexions initiées sur cette compétence majeure dans nos communautés

Drawing space : from early sketches to finished artwork : rsearch on a personal language through experimentation

This final work explores my obsession about space through personal practice. Its experimental nature seeks to open new paths, as well as overcome some limitations in the exercise of drawing, and focuses on the following topics: The quest for more sensitive means of spatial representations and solutions to evoke depth, perspective and movement other than the figurative techniques. Finding my own graphical and plastic language embedded into the physical and psychological experience of space, exploring other forms of creative and sensitive expression. The practical research project that was developed is also supported by a written part which includes a critical analysis of my work as well as an element of research on the Portuguese artist Nadir Afonso, and the Ethiopian born, New York based contemporary artist Julie Mehretu; both of whom´s work is deeply rooted into the expression of space, and their abstract languages convey a strong presence of physical reality whilst going beyond our visual perception of the world; characteristics in the representation of space which I find extremely interesting and justify my choice to study them. Furthermore, I thought that the fact their narrative and style are very different from each other would make for an interesting confrontation to explore. The result of my immersion in their work, and the process of finding within it references for my own personal development, allowed me to open up my mind to a new way of looking at space, giving me new means by which to express it, and helped me clarify some underlying paradoxes with which I’ve fought about the medium. At the same time it helped me refine my interest in the relationship between the man-made and Nature linked to a more metaphysical dimension. Overall the development of this project is a testimony of how I gained confidence to break out of my comfort zone, bringing the initial sketch into becoming a fully autonomous drawing, and how engaging into the abstract opened for me a door to a whole new plane in which I can translate feelings and emotions related to the experience of spac

RAMAN SPECTRA OF AQUEOUS FLUID INCLUSIONS: EFFECT OF MINERAL BIREFRINGENCE AND METASTABILITY ON SALINITY MEASUREMENT

International audienceIntroduction: Crustal fluids play a major role in ore deposits, basin diagenesis and metamorphic reactions, among others. The knowledge of the chemical composition of individual fluid inclusions is essential for the understanding of past fluid transport and circulations. Microthermometry, by the observation of specific phase transitions as a function of temperature, is the general approach to determine salinity in aqueous fluid inclusions [1]. However in some cases, this method cannot be carried out because of, for instance, difficulties encountered in carrying optical observations, metastabil-ity, or if the thermodynamic system is not enough constraint. Besides, some minerals are highly cleavable, particularly carbonates, and consequently fluid inclusions might easily stretch, leak or decrepitate during freezing or heating on the heating-cooling stage, because of the volume expansion of the content with temperature. In replacement of microthermometry, salinity can be determined by Raman spectroscopy using a method based on the change of the shape of the water stretching vibration band with salinity. This change is due to the decrease of the strength of the hydrogen bonds in water by dissolved anions, often chloride [2,3]. An increase of the chloride concentration results in a decrease of the intensity of the OH stretching vibration band of water around 3200 cm-1. Different methods of treatment of the raw spectrum correlate the deformation of the OH stretching vibration band of water to chlorinity [4-9]. The Raman signal of water is also sensitive to the fluid density and the birefringence of the host crystal. Birefringence is critical in quartz and carbonates, and more generally in all highly birefringent minerals. Depending on the crystallographic orientation of the sample , the value obtained for salinity in quartz samples displayed variations higher than 50 % [5,7-9]. It has been observed that the " true " value is measured when the crystal is at its extinction position [6-9]. However, the optical phenomena behind the effect observed on the Raman spectra are not elucidated. Moreover, only the case of quartz was studied. Consequently, there is no general method at this time to determine salinity from the Raman signal of water in birefringent minerals. Met-astability may also affect the OH stretching vibration band of liquid water, the decrease of the fluid density affecting the strength of hydrogen bonds. Objectives: The purpose of the present study is to measure the effect of (i) metastability and (ii) mineral birefringence on the Raman spectra of water in aqueous fluid inclusions, in order to define a protocol to obtain accurate salinity measurement in any minerals, as an alternative to microthermometry