1,720,954 research outputs found
Extraction and structural characterization of the polysaccharide fraction of Launaea acanthodes gum
No full textIn this work a physico-chemical characterization of the polysaccharide fraction of the exudates of Launaea acanthodes, a common medicinal species in central regions of Iran, was performed.
The extraction of the polysaccharide fraction of the exudates was described. The structure characterization of the polysaccharide was performed with mono and bi-dimensional NMR spectroscopy techniques, which allowed the chemical composition and the relative monomers abundance of the extracted fraction to be estimated. The constituent monosaccharides were predominantly galactose, rhamnose, arabinose and galacturonic acid residues. Interchain association phenomena in the main arabinogalactans component (Mw = 33.550 Da) were evidenced both from high-performance size-exclusion chromatography (HP-SEC–TDA), and by intrinsic viscosity ([η]0 = 0.323 dl g−1 in water and [η]0 = 0.115 dl g−1 in NaNO3 0.1 M at 20 °C) measurement and the Huggings coefficient λ. Due to the formation of hyperentanglements, a unique function of C[η]0 cannot be defined. The technological consequence was that once structured, the polysaccharide network did not express a sufficient degree in polymer orientation and therefore cast films showed weak mechanical properties
Estrazione e caratterizzazione strutturale della frazione polisaccaridica estratta dall’essudato di Launaea Acanthodes
No full textMediante analisi di light scattering, tecniche mono e bidimensionali di spettroscopia NMR e viscosimetria capillare la è stata caratterizzata la frazione polisaccaridica dell’essudato di Launaea Acanthodes. Le analisi strumentali hanno permesso di definire che il polisaccaride è costituito da unità di galattosio, ramnosio, arabinosio e residui di acido galatturonico. E’ stata dimostrata la presenza di strutture aggregate che vengono escluse nel calcolo della distribuzione del peso molecolare. I valori bassi dei raggi idrodinamico e di girazione indicano una compattezza strutturale delle macromolecole nelle condizioni di analisi. Il polimero possiede una conformazione random-coil ad elevata densità strutturale. Una via utile per investigare le capacità di strutturazione dell’arabinogalattano allo studio è stata la produzione di sottili pellicole di polimero ottenute per evaporazione dl solvente. I film ottenuti si presentano opachi e con scarse proprietà meccaniche: elevata fragilità, elasticità e resistenza alla trazione scarse. L’indagine morfologica tramite SEM indicano una struttura non uniforme, priva di una precisa orientazione dei polimeri
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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