1,720,959 research outputs found
A global survey of the stable isotope and chemical compositions of bottled and canned beers as a guide to authenticity
No full textThis study presents a dataset, derived from the analysis of 162 bottled and canned beers from around the globe, which may be used for comparison with suspected counterfeit or substitute products. The data comprise δ2H and δ18O compositions of the whole beer and δ13C compositions of the dry residue (mostly sugar) together with the concentrations of five anions (F, Cl, NO3, SO4, PO4) and seven cations (Ca, K, Mg, SiO2, V, Mn, Sr). A strong correlation, consistent with natural waters but offset from the Global Meteoric Water Line, was observed between the δ2H/δ18O composition of the beers. The extent of the offset could be explained by the brewing process and the alcohol and sugars present in the beers. Correlations between inorganic analytes were consistent with the addition of salts in the brewing process. Beers were classified as follows: ale, lager, stout or wheat-beer and the chemical composition was found to be characteristic of the assigned type, with lagers being the most readily classified. A combination of chemical and isotopic data was found to be characteristic of the geographical origin (on a continental scale) and could most easily identify beers from Australasia or Europe. A global map of δ18O data revealed a geo-spatial distribution that mirrored existing maps of the isotopic composition of annual precipitation. This confirmed a commonsense view that local precipitation will be the primary source for the water used in brewing. Using this isoscape (or alcoscape) it may be possible to assess the geographical origins of samples for which genuine comparative samples cannot be obtained.No Full Tex
Ion chromatography and ion chromatography / mass spectrometry as a complementary analysis technique for amino acid analysis in food, a review
No full textBackground: Amino acids are the building blocks of life. Nine of the 20 common amino acids need to be consumed from food, as they are not created within the body. Current amino acid analyser methodology requires either derivatisation which can be problematic or use of a mass spectrometer which can be costly. Scope and Approach: This review presents the contemporary knowledge of amino acid analysis in food by Ion Chromatography as reported recently (last 20 years). This review covers all aspects of sample types, hydrolysis methods, extraction techniques and comparisons to more conventional methodology. Chromatography methods and detector waveforms are also presented, so that between method comparisons can be achieved. Similarities and differences between these methods are discussed. Key Findings and Conclusions: Most sample extraction, chromatography and waveform methodology used for ion chromatography amino acid analysis can be drawn back to a foundational paper published in 2002. Neutralisation and rehydration methodology in contrast, differs from paper to paper. No literature was found on ion chromatography / mass spectrometry for amino acid analysis in food, which allows for a vast avenue of future directions to be explored using this evolving technique.Full Tex
Fraction collection of bioactive compounds from ion chromatography: No longer mission impossible
No full textThis paper demonstrates the fraction collection of the novel sugar trehalulose, using a modified ion chromatograph. The Ion Chromatography (IC) method, previously published for the analysis of trehalulose, was augmented with a suppressor and purpose-made switching valve unit. A sample of stingless bee honey was then run, following the three main steps:
•Separation of trehalulose fraction
•Lyophilization
•Confirmation of trehalulose
The method should be applicable to not only sugar analysis but to any bioactive compound separable by IC. The authors were not able to find a similar method within currently published literature.Full Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
