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Metodo per la concentrazione di soluzioni acquose concentrate, quali osmotizzanti o simili
No full textPoly(1,4-naphthylene sulfide) oligomers: electronic and vibrational spectra of the pristine and oxidized forms
No full textSintesi su Fase Solida di Oligopeptidi Modificati via Reazione Multicomponente di Passerini
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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
Reazioni Multicomponente Seguite da Trasformazioni Secondarie: un Valido Strumento per la Chimica Combinatoriale
No full textGels of zirconium phosphate in organic solvents and their use for thepreparation of polymeric nanocomposites
No full textGels of a-zirconium phosphate (a-ZrP) in water have been prepared by exfoliation of crystalline a-ZrP induced by intercalation–deintercalation of propylamine. Although these gels are X-ray amorphous, their Raman spectra indicate that the a-type layers of the starting material remain essentially unaltered. Replacement of gel water with water miscible organic solvents has allowed the formation of a-ZrP gels in a great variety of solvents, such as alkanols, N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), acetone, tetrahydrofuran (THF) and even chloroform. Particular attention has been devoted to a-ZrP gels in DMF. On the basis of the surface area of the dry gels, the average thickness of the particles of exfoliated a-ZrP has been estimated between 25 and 80 nm for a-ZrP percentages in the starting gels between 2.5 and 10 wt%, respectively, in agreement with SEM images. a-ZrP gels in THF have been used for the preparation of polystyrene/ a-ZrP nanocomposites with filler loadings up to 8 wt%. The presence of exfoliated a-ZrP delays the beginning of thermal decomposition of the polymer by a maximum of 45 uC for 4 wt% filler loading.The state of filler exfoliation has been confirmed by transmission electron microscopy
Vibrational and XRD study of the system CdWO4-CdMoO4
No full textMixed oxide powders belonging to the system CdMoxW1-xO4 have been prepared by a hydrothermal method. They have been characterized by the Rietveld analysis of their XRD patterns and by IR and Raman skeletal spectroscopies. Virtually pure wolframite-type structures have been obtained for x less than or equal to 0.25 and virtually pure scheelite-type structures have been obtained for x greater than or equal to 0.75. The vibrational spectra of both phases have been interpreted on the basis of the correlation method. In both solid solutions the Raman peaks due to the stretching modes of ''terminal'' W,Mo-O bonds split, while the corresponding IR bands shift significantly. The effect of the nature of tungsten coordination on the vibrational spectra is briefly discussed in relation to the use of vibrational spectroscopies to determine the structure of the surface species in supported tungsten oxide catalysts
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