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[en] A fluorescence study of the orthorhombic → trigonal phase transition, in LaxEu1-xAlO3 solid solution is presented. The measurements were performed with the sample included inside an optrode at the tip of an optical fiber. A strong composition dependent structural modification is shown at -1960C. At the composition of x=0.5 the temperature of transition is about 600C. The critical evolution of the 5D0 → 7F1.2 fluorescence lines provides a good measurement of the temperature. Under the chosen temperature range, the high relative sensitivity is from 4 to 8 per cent0C. We discuss the advantages of this kind of thermal probe and its possible extensions
[fr]
Nous presentons une etude par fluorescence de la transition orthorhombique → rhomboedrique d'aluminates de terres rares mixtes LaxEu1-xAlO3. Les mesures sont realisees avec des echantillons inclus dans une optrode, a l'extremite d'une fibre optique. D'importants rearrangements structuraux, dependant de la composition, sont mis en evidence a -1960C. Pour la composition x=0.5 presentee ici, la temperature de transition est ≅ 600C et l'evolution critique des raies de fluorescence 5D0 → 7F1.2 fournit une mesure de la temperature. La sensibilite relative est elevee, de 4 a 8 pour cent0C suivant la plage d'utilisation souhaitee. Nous discutons comparativement les merites de ce type de sonde de temperature et ses extensions possiblesJournal
[en] In this review the physical basis of the ion scattering spectrometry (ISS) are presented. The justifications, consequences and limitations of the binary elastic collision model between the projectile ion and the target surface atom are reviewed critically. The choice of the experimental conditions leading to information limited to the first surface monolayers is discussed. By a few examples, the possibilities of ISS applications are suggested. 21 refs
[fr]
Dans cette mise au point, les principes physiques qui sont a la base de la spectrometrie de diffusion ionique (ISS) sont presentes. Les justifications, consequences et limitations du modele de collision elastique binaire entre l'ion projectile et l'atome cible de surface, sont revus de maniere critique. Le choix des conditions experimentales est discute en vue de l'obtention d'une information limitee aux premieres monocouches de surface. Par quelques exemples, les possibilites d'application de l'ISS sont suggereesJournal
[en] A new, simple and selective spectrophotometric method for the determination of molybdenum in rock, alloy steel, coal ash, ore, cowdung ash and fertilizer based on the formation of a ternary complex in benzene among Mo(V), SCN- and N-octyl-N-phenylbenzamidine (OPBA) has been established. The method is applicable over wide acidity range 2.0-7.0 M HCl/2.0-6.0 M H2SO4. The effect of kinds of amidines, reducing agents and organic solvents on the extraction of the metal and colour intensity of the complex are discussed. The tolerance limit of diverse ions examined is very high. Niobium interferes seriously and is removed by masking with oxalate. The molar absorptivity and detection limit of the method with OPBA are (1.95±0.02) x 104 l. mole-1 cm-1 and 0.01 μg.ml-1, respectively. The relative standard deviation of the method at a level of 30 μg Mo/15 ml is ± 1%
Journal
[en] Fluorescence of the complexes Eu-EDTA (ethylene diamine tetraacetic acid) is studied from 77 K to 373 K. The method proves to be particularly well suited for exciting fluorescence with laser (continuous or pulsed) because of the geometry of the laser beam. It is proposed to attribute the two kinds of spectra observed to the two complexes 1Eu/1EDTA and 1Eu/2EDTA the proportion of which vary with temperature, pH and the overall solution composition. Results are obtained for Eu3+ concentrations ranging from 0.15 to 0.04 M with a spectral resolution of 1 A necessary to isolate the two 5D0 → 7F0 components. Finally we try to estimate if the use of optical fibers in collecting lanthanide luminescence is suitable for other solutions such as complexes with biological compounds
[fr]
Nous presentons quelques resultats concernant la prise de donnees par fibres optiques en solution: l'exemple choisi est celui des complexes Eu-EDTA (acide ethylene diamine tetraacetique). Grace a l'emploi des fibres optiques, nous avons pu, tres commodement, realiser une etude de la fluorescence en fonction de la temperature entre 77 K et 373 K. Cette methode est particulierement bien adaptee aux excitations laser, continu ou pulse, en raison de la geometrie du faisceau. Nous discutons les resultats obtenus sur les complexes Eu-EDTA en fonction des travaux d'autres auteurs et proposons d'attribuer les deux spectres observes aux complexes 1Eu/1EDTA et 1Eu/2EDTA dont la proportion varie avec la temperature, le pH et la composition totale de la solution. Enfin, nous essayons d'estimer la possibilite d'utiliser les fibres optiques dans les mesures de fluorescence des complexes Ln -substances biologiquesJournal
[en] The use of nitroxides as contrast agents for Magnetic Resonance Imaging requires knowledge of the in vivo distribution of the product. Aqueous nitroxide solution is injected intravenously into a rat. The animal is killed 20 minutes later and the nitroxide concentrations in the tissues and biological fluids are measured using Electron Paramagnetic Resonance. Two nitroxides present interesting localization in the kidneys and in the heart
[fr]
Pour utiliser un nitroxyde comme produit de contraste en imagerie par Resonance Magnetique Nucleaire, il faut connaitre sa localisation dans l'organisme. Cette biodistribution a ete determinee par Resonance Paramagnetique Electronique sur des rats. Sur les trois nitroxydes testes par cette methode, deux presentent des biodistributions interessantes: un se fixe preferentiellement sur le coeur, un autre sur les reinsJournal
[en] A thermodynamic and kinetic study of niobium(V) complexation with 4-(pyridyl-2-azo)-resorcinol (PAR) has been done in order to define the experimental conditions for a kinetic determination of niobium(V). Fixed time kinetic measurements were used for this analysis. Interference of tatalum(V) was studied and eliminated by sodium tartrate addition. The determination range of niobium(V) is from 2.10-5 mol l-1 to 5.10-7 mol l-1 with a reproducibility of 3% (R.S.D.). The kinetic determination lasts 30 seconds instead of 30 to 45 minutes for an equilibrium method
[fr]
Une etude thermodynamique et cinetique de la reaction de complexation du niobium(V) par le 4-(pyridyl-2-azo)-resorcinol (PAR) a permis de definir les conditions d'un dosage cinetique du niobium(V). La vitesse de complexation a ete mesuree a des intervalles de temps fixes, proches du temps initial. L'interference du tantale(V) sur cette determination analytique a ete etudiee et eliminee grace a l'addition de tartrate de sodium. Le niobium(V) peut etre dose a des concentrations comprises entre 2.10-5 mol l-1 et 5.10-7 mol l-1 avec une reproductibilite de 3% (coefficient de variation) en 30 secondes par la methode cinetique au lieu de 30 a 45 minutes par une methode a l'equilibreJournal
[en] The removal of molybdenum from an aqueous solution by the combined use of sodium diethyldithiocarbamate (Na DDTC) and oleic acid γHOL) was studied by flotation technique. The effect of variables such as Na DDTC, HOL concentrations and pH on the floatability were examined. About 98% of the molybdenum could be floated under the optimum conditions. In the investigation of molybdenum by atomic absorption spectrophotometry, Na DDTC was used to eliminate the interference effects of cations by its adding to both the sample and the standard solutions of cations. Also, the mechanism of this elimination was discussed. The interfering effects of some cations in different acid media and the phenomenal interference in presence of heteropoly atoms were explained. Moreover, the effect of multicomponent mixtures of cations was elaborated. 20 refs
Journal
[en] Electronic paramagnetic resonance allows the detection of ionized food only after dry storage, avoiding reaction of radicals with water. Dry and solid parts are used for analysis (bones for meat and fish, kernels for fruits). Dosimetry is possible by EPR spectrometry of alanine-L fixed on products treated in industrial irradiators
[fr]
La resonance paramagnetique electronique permet la detection des aliments ionises si le stockage est effectue a sec les radicaux reagissant avec l'eau. La RPE peut etre utilisee en tant que preuve sur les parties seches (os pour la viande, aretes de poissons, noyaux des fruits). La RPE est aussi reconnue comme methode de dosimetrie par mesure des radicaux libres dans la L-alanine que l'on peut fixer sur les produits traites dans les irradiateurs industrielsJournal
[en] The paper reviews briefly the application of gamma radiation to preservation of cultural objects for disinsectization, disinfection and strengthening of materials such as wood or stone by impregnation with a liquid resin and in situ polymerization. As heavy equipment is required two facilities are specialized a 1000 T Bq cobalt 60 source at Grenoble (France) and 100 T Bq one at Rostoky (Czechoslovakia). Examples of treated objects are given
[fr]
On passe en revue l'application du rayonnement gamma a la conservation des biens du patrimoine culturel pour la desinsectisation, la desinfection et: - la consolidation des materiaux degrades tels que la pierre, ou le bois, par leur impregnation avec une resine liquide radiopolymerisee in situ. La mise en oeuvre de ces techniques necessitant des equipements lourds, il y a deux installations: a Grenoble (ARC-Nucleart) et a Rostoky (Tchecoslovaquie) de 1000 T Bq et 100 T Bq respectivement. On donne des exemples d'objets traitesJournal
[en] Polycrystalline and non-perfect silicon used for solar cells, cannot be controlled solely by physical methods. For that purpose, we developed multielement analytical methods able to determine very low concentrations of impurities. About thirty elements are determined by activation in neutrons and gamma photons between 0.000001 and 1 νg.g-1. Eleven elements are determined by inductively coupled plasma emission spectrometry between 0.002 and 1 νg.g-1. Both methods were used to develop a very effective purification process for silicon, based on zone refining by melting under a high pressure inductively coupled plasma
[fr]
Le silicium imparfait et polycristallin utilise dans les cellules solaires ne peut pas etre controle uniquement par des methodes physiques. Dans ce but, nous avons developpe des methodes analytiques multielementaires pour doser des concentrations tres faibles d'impuretes. Trente elements environ sont doses par activation dans les neutrons et les photons gamma entre 0,000001 et 1 νg.g-1. Onze elements sont doses par spectrometrie d'emission au plasma inductif entre 0,002 et 1 νg.g-1. Ces deux methodes, tres complementaires, ont ete utilisees pour mettre au point un procede tres efficace de purification du silicium, fonde sur la fusion de zone sous plasma inductif haute frequenceJournal
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