1,721,829 research outputs found
Colloidal dispersion of gold nanoparticles
Full text linkStable sols of gold nanoparticles with an average diameter of about 13 nm were prepared from hydrogen tetrachloroaurate (prepared from bulk metallic gold) and trisodium citrate dihydrate. The organic salt acts as reducing as well as stabilizing agent for the gold nanoparticles, having an average diameter of 13±4 nm. The deep purple colloidal suspension is stable for several weeks. UV-Vis absorption spectra shows the typical surface plasmon resonance band of nanosized gold with an absorption maximum at 521.5 ± 0.5 nm
Potassium uptake in the epiphytic lichen Hypogymnia physodes at concentrations and pH conditions as found in stemflow
No full textSamples of the foliose epiphytic lichen Hypogymnia physodes were incubated with 0, 100, 500, and 1000 muM KCl solution for up to 120 min. K was absorbed by H. physodes only in single replicates of the most highly concentrated solutions. Otherwise a release of K of up to 26 mumol g(-1) d. wt. was observed. This can be attributed to the low affinity of K for the cation exchange sites in lichen cell walls. The K concentrations applied with the incubation medium correspond to concentrations found in stemflow from dieback-affected Picea abies forests in the Harz Mountains, northern Germany. The results suggest that stemflow is not a major source of K for H. physodes. The loss of K in the present experiment could be due to changes of the water content in the lichen thalli or due to membrane damage caused by S or heavy metals in the field
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
Construction and Characterization of Ru(II)Tris(bipyridine)-Based Silica Thin Film Electrochemiluminescent Sensors. L. Armelao, R. Bertoncello, S. Gross, D. Badocco and P. Pastore,
No full textRu(II) tris-bipyridine based ECL sensors were produced by embeddingthe complex inside silica glass thin films
deposited via a sol-gel dipping procedure on K-glass conducing substrates. Films were prepared starting from a prehydrolyzed
ethanolic solution of Si(OC2H5)4 and Ru(bpy)3Cl2. Transparent, crack-free and homogeneous reddish
silica layers, havinga thickness of 20020 nm, were obtained. The films, either deposited at room temperature or
thermally annealed at 100, 200 and 300 C for 30 h, were structurally and chemically characterized. Ru(bpy)3Cl2
thermal stability was previously checked by thermogravimetric analysis (TGA). The films were investigated by X-Ray
photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and UV-vis spectroscopy. XPS in-depth
profiles revealed a homogeneous distribution of the ruthenium complex inside the silica thin layers. SIMS data
suggested that the embedded Ru(bpy)3Cl2 did not react with oxygen inside the oxygen-rich silica matrix to give Ru-O
bonds. Electrochemical and ECL characterization of the thin film electrodes were made by means of cyclic
voltammetry (CV) and controlled potential step experiments. The ECL sensor showed a diffusive redox behavior of
the Ru(bpy)3
2+/Ru(bpy)3 3+ system. Light emission produced from the reaction between oxalic acid and the
electrogenerated Ru(bpy)3
3+ was larger and stable when thermally treated electrodes were used after a suitable
hydration period. The 300°C treated sample was the best performingsensor both in terms of low complex leakage and
sensitivity. Calibration plots relative to oxalic acid were obtained both in stationary and in flowingsolutions in the
concentration range 2uM - 300 uM. A linear behavior appeared in the former case, while in the latter a slight
curvature was evident as a consequence of a finite diffusion time of the analyte inside the thin film. The signal
repeatability, obtained by multiple 100 uL of 10 uM oxalic acid injections in flowingsolutions , was better than 4%.
The obtained detection limit (computed as three times the standard deviation of the base-line noise) was 10-6M as
oxalic acid
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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