1,721,021 research outputs found
Application of electrospray ionization mass spectrometry to the study of grape anthocyanins
No full textA rapid method for the qualitative and semi-quantitative determination of grape anthocyanins has been developed. It consists of extraction of anthocyanins from grape skins with an ethanol/water/hydrochloric acid solution, purification and concentration by solid phase extraction, and analysis of extracts by direct infusion electrospray mass spectrometry and ion trap multiple mass spectrometry. Two different cultivars of hybrid grapes and a cultivar of Vitis vinifera grape were analyzed and they showed different anthocyanin profiles. Among the compounds detected and characterized in the extracts, four anthocyanin-3-(6-O-p-coumaroyl)5-O-diglucosides were identified in Clinton grape for the first time and their electrospray ionization mass spectra could be obtained for the first time together with those of cyanidin, peonidin, and malvidin 3,5-O-diglucosides. For malvidin 3,5-O-diglucoside and 3-O-monoglucoside a semi-quantitative determination could be achieved that would result interesting for the identification of hybrid grapes and wine
Grape and wine contaminants: ochratoxin A, biogenic amines, trichloroanisole and ethylphenols
No full text
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
High-resolution mass spectrometry identification of secondary metabolites in four red grape varieties potentially useful as traceability markers of wines
Full text linkLiquid chromatography coupled to high-resolution mass spectrometry (LC-Q/TOF) is a powerful tool to perform chemotaxonomic studies through identification of grape secondary metabolites. In the present work, the metabolomes of four autochthonous Italian red grape varieties including the chemical classes of anthocyanins, flavonols/flavanols/flavanones, and terpenol glycosides, were studied. By using this information, the metabolites that can potentially be used as chemical markers for the traceability of the corresponding wines were proposed. In Raboso wines, relatively high abundance of both anthocyanic and non-anthocyanic acyl derivatives, is expected. Potentially, Primitivo wines are characterized by high tri-substituted flavonoids, while Corvina wines are characterized by higher di-substituted compounds and lower acyl derivatives. Negro Amaro wine’s volatile fraction is characterized by free monoterpenes, such as α-terpineol, linalool, geraniol, and Ho-diendiol I. A similar approach can be applied for the traceability of other high-quality wines
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
Changes in volatile compounds of grape pomace distillate (Italian grappa) during one-year ageing in oak and cherry barrels
No full textThe Italian grape pomace distillate grappa is often refined by ageing in wooden barrels. Chemical changes of the volatile profile of two samples produced from a Cabernet Sauvignon/Merlot blend and Prosecco pomace both at two ethanol contents (55% and 68%) were studied during one-year ageing in cherry and oak barriques. Grappa variety, ethanol content and barrel type strongly affected the volatiles profile of the distillates. Oak-aged grappa contained 10-fold the wood volatiles of the cherry-aged one, but the latter had higher levels of syringaldehyde, coniferaldehyde, and 3,4,5-trimethoxyphenol; 55% ethanol extracted higher levels of wood compounds and ethoxy-compounds were higher in the 68%-ethanol distillates. Prosecco grappa extracted higher wood compounds and showed no significant changes in the levels of fruity/floral esters and terpenols. Findings of this study can be also useful in the development of new ageing processes of distillates for which cherry barrels are still not used (e.g., brandy and whisky)
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
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