1,721,042 research outputs found
Synthesis of 8-hydroxyquinoline functionalised DO3A ligand and Eu(III) and Er(III) complexes: Luminescence properties
No full textThe synthesis of a new DO3A-based macrocyclic ligand bearing a 8-hydroxyquinoline residue together with the preparation of its Eu(3+) and Er(3+) neutral complexes are described. In a previous report IF. Rizzo, A. Papagni, F. Meinardi, R. Tubino, M. Ottonelli, G.F Musso, G. Dellepiane. Synth. Met. 147 (2004) 1431, we have shown that lanthanide complexes display very high stability combined with a good luminescence in aqueous solution under UV radiation, which indicate an energy transfer process from the excited 8-hydroxyquinoline moiety to the metal. In this work, we correlate the ability to transfer the energy from the sensitizer to lanthanide ion with pH behaviour of the antenna. Furthermore, the variation of pH in Eu(3+) complex supports the hypothesis of presence of charge-transfer transitions. The good Solubility and sensitized emission in different solvents (organic and water) are very important aspects for their technologic applications as luminescent probes or NIR-emitting devices. (C) 2009 Elsevier B.V. All rights reserved
A study of the electrical properties controlled by residual acceptors in gallium antimonide
No full textUpconversion-induced fluorescence in multicomponent systems: Steady-state excitation power threshold
Get PDFWe have analyzed the dynamics of the upconversion-induced delayed fluorescence for a model multicomponent organic system, in which high concentrations of triplet states can be sustained in steady-state conditions. At different excitation powers, two regimes have been identified depending on the main deactivation channel for the triplets, namely, the spontaneous decay and the bimolecular annihilation. The excitation power density at which triplet bimolecular annihilation becomes dominant is the threshold (I(th)) to have efficient upconversion generation. The simple equation obtained for I(th) allows us to predict the theoretical efficiency of a generic system on the basis of few parameters of the constituent molecules
Microstructure imaging of C54-TiSi2 polycrystalline thin films by micro-Raman spectroscopy
No full textThe morphology of C54-TiSi2 polycrystalline films has been revealed by the micro-Raman imaging technique. This was based on the calculation of the symmetries of the Raman active vibrations of the C54-TiSi2 single crystal and subsequent polarized Raman measurements to detect and unambiguously label all the expected peaks. The relative intensity of two suitable peaks was monitored and mapped on C54-TiSi2 blanket films. Grains with different orientation are clearly detectable, and the microstructure properties of the film can be analyzed. (C) 1999 American Institute of Physics. [S0003-6951(99)01746-5]
DFB laser action in a flexible fully plastic multilayer
No full textAn all-plastic distributed-feedback flexible multilayer laser (FML), able to keep its lasing characteristics even upon strong bending from planarity, is proposed and the possibility of using this system to make solid-state dye lasers is suggested
Lasing in one dimensional dye-doped random multilayer
No full textLasing action in a fully organic dye doped flexible 1D random multilayer photonic crystal is reported. The emission energy can be modulated by varying layers thicknesses to fit the dye characteristics, thus showing the potential interest of such cheap materials in active devices for optoelectronic applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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