1,721,050 research outputs found
Advances in LC-MS for food analysis
No full textWithin the wide host of hyphenated techniques, liquid chromatography-mass spectrometry (LCMS) has recently emerged to a central role in different fields, including food analysis. In this review, the most recent LC-MS approaches are overviewed; technical requirements for linkage of an LC system to an MS one, are also briefly discussed. In addition, advantages to be gained by the employment of on-line 2DLC in the “comprehensive” mode are illustrated, as well as selected applications for the analysis of most common foodstuffs, namely triacylglycerols, carotenoids, and polyphenols. Finally, future trends toward the use of LC-MS in the food field are reported
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
High performance characterization of triacylglycerols in milk and milk-related samples by liquid chromatography and mass spectrometry
No full texttIn this work, ultra high performance liquid chromatography was used for the characterization of non polar lipids (triacylglycerols) in milk samples of different origin, as well as milk-derivatives. For tackling sucha task, three core shell type octadecylsilica columns were serially coupled, reaching a total stationaryphase length of 45 cm, using acetonitrile-isopropanol gradient elution allowing triacylglicerol separa-tion according to increasing partition number. The employment of an ion-trap-time-of-flight detectionin conjunction with atmospheric-pressure chemical ionization mass spectrometry was carried out topositively identify a number of 243 different triacylglycerols containing up to 22 fatty acids, with 2-22carbon atom alkyl chain length, and 0-3 double bonds. This work reports an extensive characterization of the triacylglycerol fraction in milk and milk-related samples of different sources
Characterisation of lipid fraction of marine macroalgae by means of chromatography techniques coupled to mass spectrometry
No full textIn this work the characterisation of the lipid fraction of several species of marine macro algae gathered along the eastern coast of Sicily is reported. Two species of green marine algae (Chloropyceae), two species of red marine algae (Rhodophyceae) and four species of brown marine algae (Pheophyceae) were evaluated in terms of fatty acids, triacylglycerols, pigments and phospholipids profile. Advanced analytical techniques were employed to fully characterise the lipid profile of these Mediterranean seaweeds, such as GC-MS coupled to a novel mass spectra database supported by the simultaneous use of linear retention index (LRI) for the identification of fatty acid profile; LC-MS was employed for the identification of triacylglycerols (TAGs), carotenoids and phospholipids; the determination of accurate mass was carried out on carotenoids and phospholipids. Quantitative data are reported on fatty acids and triacylglycerols as relative percentage of total fraction. © 2013 Elsevier Ltd. All rights reserved
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
Syringopleural shunt as a rescue procedure in patients with syringomyelia refractory to restoration of cerebrospinal fluid flow
No full textSyringomyelia should be treated by reconstruction of the subarachnoid space and restoration of cerebrospinal fluid homeostasis. Direct intervention on the syrinx is a difficult choice and should be considered a rescue procedure. Data in the literature examining the various options are scanty, with generally unsatisfying results. We report our experience with shunting of the syrinx into the pleural space
Determination of the triacylglycerol fraction in fish oil by comprehensive liquid chromatography techniques with the support of gas chromatography and mass spectrometry data
No full textFish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge number has never been reported for a menhaden oil sample.The main disadvantage of such an approach over the stop-flow one was the longer analysis time, mainly attributable to solvent exchange between the two dimensions
Blood orange (Citrus sinensis) as a rich source of nutraceuticals: investigation of bioactive compounds in different parts of the fruit by HPLC-PDA/MS
No full text: This study is part of a wider investigation aimed to sustain the economical value of the by-products generated by the Citrus industry. In particular, the protected geographic indication (PGI) red orange of sicily (known as blood orange) has been analysed by HPLC and by the enzymatic AOAC method. All the by-products contain significant amounts of biologically active compounds (limonoids and flavonoids). The decanted pulps were the most abundant, with the highest amount of flavonoids (130 g/kg) and high amount of limonoids (5.5 g/kg). Seeds were the best source of limonoids with about 10 g/kg. Low amount of anthocyanins were found only in coarse pulps and waste water. The total, the insoluble and the soluble dietary fibre (TDF, IDF and SDF respectively) were also determined. The pulps resulted to be the best source of dietary fibre, based on the amount and on the best insoluble/soluble ratio
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