1,721,028 research outputs found
Comparison of Three Accelerated Oxidation Tests Applied to Red Wines with Different Chemical Composition
No full textBACKGROUND: Three accelerated oxidation tests were proposed to simulate red wine oxidation thus providing information useful to correctly manage moderate oxygen exposure of wine during aging in regard to phenolic composition and wine color. Since the results of the tests have never been compared on wines with different initial composition, the aim of this study was to find a suitable method to simulate oxidation of any still red wine. METHODS: Aglianico, Barbera, Gaglioppo, Magliocco, and Nerello wines were treated with (1) three cycles of air saturation, (2) the addition of hydrogen peroxide, and (3) the addition of acetaldehyde. Changes in chromatic characteristics and phenolic composition were determined by spectrophotometric and HPLC methods. RESULTS: Important differences in the behavior of the different wines were detected: the highest formation of polymeric pigments was observed in Barbera and Aglianico wines. In contrast, Gaglioppo and Magliocco wines showed a lower variability before and after the oxidation probably due to the lower anthocyanin/tannin ratio. Among the accelerated oxidation tests applied, no significant differences in color parameters and phenolic composition were detected in samples treated with the addition of H2O2 and the air saturation method. CONCLUSION: The study demonstrated that H2O2 addition is a successful tool to predict the evolution of different phenolic compounds during the air saturation treatment of wines
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
Anthocyanins and nucleation seeds are key factors affecting quercetin precipitation in red wines
No full textBackground: Climate changes have been leading to an excessive synthesis of quercetin (Q) and its glycosides (Q-Gs) in specific red grape varieties, such as Sangiovese. This has resulted in concentrations overcoming the solubility threshold of Q in wines, with the consequent formation of undesirable precipitates. This study aims at assessing the impact of various factors, including anthocyanins, temperature, nucleation seeds and time, on the precipitation of Q in red wine. Results: The influence of anthocyanins on Q solubility was examined by adding a grape skin extract rich in anthocyanins to a model solution containing 89 μmol L−1 of Q. The data revealed that the solubility of both Q and Q-Gs increased as a function of the anthocyanin concentration in the model solution. In a subsequent experiment, red wines were stored at two different temperatures (2 and 20 °C), supplemented with Q nucleation seeds, and monitored over a 10-day period. Notably, after only 3 days of contact with Q seeds at 2 °C, a reduction of over 75% in Q concentration was observed in the supernatant. Among the considered factors, contact with nucleation seeds emerged as the most significant one (P < 0.0001). Conclusion: Q precipitation in red wines is influenced by the presence of anthocyanins in solution, although it is not the sole determinant. The data also suggested that a potential strategy for wineries to mitigate the risk of Q precipitation in bottled wine would be the acceleration of this process by promoting the formation of nucleation seeds. © 2024 Society of Chemical Industry
Discovery of a novel class of reversible non-peptide caspase inhibitors via a structure-based approach
No full textIn this paper, we report a simple structure-based iterative optimizations (SUBITO) strategy to identify and optimize new protein ligands and inhibitors. The approach is based on a combination of NMR-based screening and computational docking methods and enabled the identification of novel chemical leads among hundreds of thousands of commercially available compounds by screening only a few hundred compounds from a scaffold library followed by iterative screening steps where only few dozen compounds are tested. As an application, we report on the discovery of a novel class of non-peptide reversible caspase inhibitors, with IC50 values in the low micromolar range. © 2005 American Chemical Society
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
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