Concentration effect on the scintillation properties of Sol-Gel derived LuBO3 doped with Eu3+ and Tb3+.

International audienceLu1-xEuxBO3 and Lu1-xTbxBO3 powders have been prepared by a sol-gel process with 0 < x < 0.15 for Eu3+ and 0 < x < 0.05 for Tb3+. The purity of powders has been verified by X-Ray diffraction and the results confirm that all the materials have the vaterite type even if the calcination has been performed at 800°C. Furthermore, the solid solution for LuBO3 vaterite is observed up to x=0.15 and x=0.05 for europium and terbium ions respectively. So doping with Eu3+ or Tb3+ ions does not affect the structure. These materials have also been analyzed by Fourier Transform Infra Red Spectroscopy. The morphology of the powders has been studied by Scanning Electron Microscopy and shows a very nice morphology with small spherical particles with narrow size distribution. Optical properties have then been studied to confirm the effective substitution of Eu3+ or Tb3+ for Lu3+ ions and to determine the materials scintillation performances. The optima, in term of scintillation yield, are obtained for Eu3+ and Tb3+ concentration of x=0.05 in both cases. The afterglows have also been measured and confirm the potentiality of these materials as scintillators

Scintillation of Sol-Gel derived Lutetium orthophosphate doped with rare earth ions.

In this paper, the synthesis, the characterization and the scintillation properties of LuPO4 doped, with several concentrations of Ce3+, Eu3+ and Tb3+ ions, are presented. These materials have been synthesized by sol-gel process. The purity of powders has been verified by X-Ray diffraction and the results confirm the xenotime structure of all the materials. A thermogravimetric analysis allows the obtention of informations on the crystallisation of LuPO4 and the study of its evolution from the amorphous to crystalline form. The morphology of the powders has been studied by Scanning Electron Microscopy and shows that the powders are constituted of small particles with narrow size distribution. Optical properties have been studied in order to determine the scintillation performances of these materials. The optima are obtained for Ce3+, Eu3+ and Tb3+ concentration of respectively 0.1%, 10% and 5% with high scintillation yields. This study thus confirms the potentialities of these materials as scintillators

Characterization and Scintillation properties of Sol-Gel derived Lu2SiO5:Ln3+ (Ln = Ce, Eu, Tb) powders

International audienceIn this paper, we report the synthesis, the characterization and the scintillation properties of sol-gel derived Lu2SiO5 (LSO) powders. Ce3+, Eu3+ and Tb3+ doped LSO powders have been synthesized by an original sol-gel process. The purity of the materials has been checked by X-Ray diffraction, confirming the elaboration of monophasic powders even for doped samples. Finally, the scintillation properties of the rare earth doped materials have been studied, the substitution of Ln3+ (Ln: Ce, Eu or Tb) for Lu3+ is confirmed, the scintillation yields have been calculated and the afterglow have also been measured, confirming the potentiality of the sol-gel derived LSO

Characterization of Sol-Gel derived scintillating LuBO3 films doped with rare earth ions.

Rare earth doped LuBO3 thin films have been prepared by combining sol-gel process and coatings techniques such as spin coating and spray pyrolysis. Annealing treatment results in the crystallization of the film as vaterite phase and incorporation of the doping ions in solid solution. XPS and RBS spectrocopies showed that the composition of the films is close to the nominal one. Adventitious carbon has been observed and attributed to incomplete pyrolysis of metal-organic precursors. XPS concentrations profiles show a good homogeneity for the films. RBS demonstrated some inter-diffusion between amorphous carbon substrate and borate films resulting in a gradient of carbon at the interface between the substrate and the film itself. Finally scintillation spectra have been recorded and demonstrate the potentiality of these films to be used as X-ray intensifying screens

Elaboration par voie sol-gel et caractérisations de matériaux scintillateurs inorganiques

CLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF

Surface characterization of sol-gel derived scintillating rare-earth doped Lu2SiO5 thin films

International audienceRare earth doped Lu2SiO5 thin films have been prepared by combining sol-gel process and spin coating. Annealing treatment results in the crystallization of the film and efficient incorporation of rare earth doping ions. XPS and RBS spectrocopies showed that the composition of the films is close to the nominal one. Adventitious carbon has been observed and attributed to incomplete pyrolysis of metal-organic precursors. XPS concentrations profiles show a good homogeneity for the films. RBS demonstrated some inter-diffusion between amorphous carbon substrate and silicate films resulting in a gradient of carbon at the interface between the substrate and the film itself

Peptide-coated nanoparticles: Adsorption and desorption studies of cationic peptides on nanodiamonds

International audienceThe functionalization of nanoparticle surfaces remains a major challenge for broader applications in biology. To study the physisorption of peptides on nanodiamonds (NDs), we developed reliable and facile methods: UV titration, MALDI-TOF mass spectrometry or fluorescence spectrophotometry. These readily applicable procedures allowed us to analyze the adsorption and desorption behaviors of different cationic peptides. A rough estimate led to propose that an average of three to four shells of amphiphilic peptides rapidly adsorbed on NDs surface: about half of the molecules being adsorbed with a high affinity, while the other half may be exchanged within a few minutes. If a photoactivatable amino acid was incorporated in the peptide sequence, the subsequent irradiation allowed similarly the coating of three to five shells of peptides on the NDs surface, but in that case peptides were not exchangeable at all, even after a few days. Stable cationic nanodiamonds may be obtained by simple physisorption of amphiphilic peptides, leading to nanoparticles with a positive zeta potential in the appropriate range for biological applications

Accumulation of Cell-Penetrating Peptides in Large Unilamellar Vesicles - A straightforward Screening Assay for Investigating the Internalization Mechanism.

International audienc

Méthodologie de collecte des données socio-économiques sur la pêche professionnelle. Guyane et Guadeloupe. Année 2020

This report describes the methodology for collecting economic data on commercial fleets in Guyana and Guadeloupe during the 2020 survey. The context and the objectives for producing indicators within the EU data collection framework, the survey is presented including the organization and collection procedure, field training and reporting as well as communication. The links to the technical documents are provided in particular the questionnaire used. The collection sampling plan is detailed with a description of, the reference population, the stratified sampling frame, the calculation of the sampling allocations. The samples are also described. The annex presents a summary of the questionnaire.Ce rapport décrit la méthodologie de collecte de données économiques sur la pêche professionnelle utilisée en Guyane et Guadeloupe lors de l'enquête 2020. Après avoir décrit le contexte et les objectifs de production d'indicateurs dans de le cadre du programme européen de collecte de données, le dispositif de l'enquête est présenté incluant l'organisation et procédure de collecte, la formation sur la terrain et le rapportage ainsi que la communication. Les liens vers les documents techniques sont fournis notamment le questionnaire utilisé. Le plan d'échantillonnage de collecte est ensuite détaillé avec une description de la population de référence, de la base de sondage stratifiée, du calcul des allocations d'échantillonnage. On décrit également les échantillons tirés. L'annexe présente une synthèse du questionnaire.

The Efficacies of Cell-Penetrating Peptides in Accumulating in Large Unilamellar Vesicles Depend on their Ability To Form Inverted Micelles.

International audience: In this study, the direct translocation of cell-penetrating peptides (CPPs) into large unilamellar vesicles (LUVs) was shown to be rapid for all the most commonly used CPPs. This translocation led within a few minutes to intravesicular accumulation up to 0.5 mM, with no need for a transbilayer potential. The accumulation of CPPs inside LUVs was found to depend on CPP sequence, CPP extravesicular concentration and phospholipid (PL) composition, either in binary or ternary mixtures of PLs. More interestingly, the role of anionic phospholipid flip-flopping in the translocation process was ascertained. CPPs enhanced the flipping of PLs, and the intravesicular CPP accumulation directly correlated with the amount of anionic PLs that had been transferred from the external to the internal leaflet of the LUV bilayer, thus demonstrating the transport of peptide/lipid complexes as inverted micelles