1,720,976 research outputs found
Biochemical evidence of Phenoloxidase Activity in Larvae of Allogamus auricollis (Insecta, Trichoptera). Comp. Biochem. and Physiol.
No full textAu-thymine, thymidine and thymidine 5’-monophosphate nanoparticles: chemical characterisation and cellular uptake studies into U87 cancer cells
No full textGold nanoparticles were obtained by reduction of a tetrachloroaurate aqueous solution in the presence of a RGD-(GC)2 peptide as stabiliser. As comparison, the behaviour of the (GC)2 peptide has been studied. The (GC)2 and RGD-(GC)2 peptides were prepared ad hoc by Fmoc syntheses. The colloidal systems have been characterised by UV-visible, ATR-FTIR, mono and bidimensional NMR techniques and Confocal and TEM microscopies. The efficient cellular uptake of Au-RGD-(GC)2 and Au-(GC)2 stabilised gold particles into U87 cells (human glioblastoma cell), were investigated by confocal microscopy and compared with the behaviour of the (GC)2 capped gold nanoparticles. A quantitative determination of the uptaken nanoparticles have been carried out by measuring the pixel brightness of the images that highlighted the importance of the RGD termination of the peptide. A deep insight of the cellular uptake mechanism was investigated by TEM microscopy. Various important evidences indicated the selective uptake of RGD-(GC)2 gold nanoparticles into the nucleus
New Au(0) sols as precursors for heterogeneous liquid-phase oxidation catalysts
No full textNew Au(0) sols were obtained by reducing antic compounds (AuCl3, NaAuC4, and HAuCl4)with reducing compounds (H2C2O4, SnCl2, and NaBH4) in the presence of protective agents [polyvinylalcohol, PVA, and poly(diallyldimethylammonium chloride), PDDA] in aqueous solutions. The sols, characterized by TEM microscopy and UV-visible spectroscopy, consisted of nanoparticles of different sizes depending on the preparation method. The colloidal solutions were immobilized on activated carbon and titania. The obtained heterogeneous catalysts were tested in the selective liquid-phase oxidation of ethylene glycol to glycolate (pO(2) = 300 kPa, T = 343 K, r.t. = 1 h, [EG] = 0.5 M, EG/Au = 1000, EG/NaOH = 1, EG = ethylene glycol). A comparison of the catalytic activity underlines the importance of using the correct sol with respect to the support. (C) 2002 Elsevier Science (USA)
Synthesis of Au(0) nanoparticles from W/O microemulsions
No full textClear W/O microemulsions of NaAuCl4 and NaBH4 Can be obtained using the four components: cetyltrimethylammonium bromide, 1-butanol, n-octane and aqueous solutions of inorganic salts. They can be mixed giving microemulsions of Au(0) nanoparticles in the micellar cores. The red gold systems have been supported on activated carbon and tested in the catalytic liquid phase selective oxidation of glycol to glycolate by O-2
Synthesis and full characterisation of nickel(II) colloidal particles and their transformation into NiO
No full textMonodispersed nickel(II) particles were achieved by ageing aqueous solutions of NiSO4·6H2O in the presence of
urea, at 90°C for 3.5 h. Working up this colloidal dispersion led to a green powder with the stoichiometry
5[Ni3(OH)5(NCO)]·[NiCO3]·[H2O]. This mixed salt was characterised by extensive spectroscopic investigations and
chemical–physical analyses. The nickel intermediate was further thermally decomposed at various temperatures,
under both aerobic and anaerobic conditions, and gave black mono dispersed particles of Ni(II) and Ni(III) oxides.
The phase transformations were studied in detail and the oxidation products (NiO and NiO(OH)) were characterised
Gold-Ligand Interaction Studies of Water-Soluble Aminoalcohol Capped Gold Nanoparticles by NMR
No full textNovel reproducible preparations of gold nanoparticles capped by aminoalcohols have been set up by reduction of
HAuCl4 with NaBH4 in aqueous solution. The characterization of Au@aminoalcohol nanoparticles performed by 1H
NMR, ATR-FTIR, UV-vis spectroscopies, and TEM microscopy highlighted the binding site and the nature of the
Au-NH bond
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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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