1,720,962 research outputs found
TRACING THE ORIGIN OF MILK AND MILK PRODUCTS: A SIMPLIFIED PROCEDURE FOR EXTRACTION/ISOLATION OF GLYCEROL FROM WHOLE MILK AND GC-IRMS ANALYSIS
No full textRecently the consumer demand of transparency and attention on foodstuff quality and safety is increasing, and, related to that, the need of qualified origin products on the market (1). Livestock feeding regimen, breeding conditions and growing environment are parameters that need to be traced to reveal origin, not only geographic, in order to certify quality, authenticity, and typicality of diary products. Isotope ratio analysis was demonstrated to be a suitable tool for determining the origin of food, milk and dairy products included (2). It is known that the ratio 13C/12C of animal products is correlated to animal diet since it discriminates between C3 and C4 plants (3), and in particular 13δ of glycerol has been shown to increase with maize amount (4). The possibility to trace OGM presence in the fodder can be speculated on the same hypothesis, since transgenic fodder is mainly made up of soybean, a typical C3 plant. Milk samples from pasture-fed and silagefed cows were collected from the Italian market and analyzed for 13C/12C ratio of glycerol. A sample preparation from whole milk was set up, specifically targeted for GC-IRMS analysis. First, proteins were precipitated, then fat was separated, and through saponification glycerol was released from triglycerides and then isolated from fat components such as fat acids. After derivatization the acetylated mixture was purified in HPLCUV. The purified fraction collected underwent GC-IRMS analysis. When compared to milk from silage-fed cows, milk from pasture-fed cows resulted enriched in 13C, showing a different diet regimen, rich in C4 plants, and therefore suggesting a GMO-free diet. Future developments of the present work will include the investigation of different isotope ratios and other parmeters such as fatty acids compositional profile and screening of milk for exogenous DNA presence. Finally the whole data collected will be processed with chemometric methods
GC-IRMS analysis to detect the use of genetically modified feed in milk production.
No full textVerifying the description of food in terms of its composition, processing or origin is challenging, but the consumers need clear and accurate information to make informed choices about their diet and the foods they buy. The problem of genetically modified organism (GMO) safety is an open question and for which the public opinion has a particular sensitivity and concern. Even if the current European standards allow the use of authorized GMOs only, it should be stressed that is mandatory to label their presence just above 0.9%, while there is no obligation to inform the consumer about their use in the production process. It follows that the consumer may be informed of the presence of GMOs in food only when it exceeds the threshold value of 0.9%, while being completely unaware if animal products were obtained by feeding the animals with even 100% GMOs. Analytical techniques based on the measurement of stable isotope ratio mass spectrometry (IRMS) were demonstrated to be a powerful tools for determining the both the geographic origin and the production system of food, milk and dairy products included. In particular, the ratio 13C/12C of animal products is able to discriminate between a diet based on C3 or C4 plants , and 13δ of glycerol has been shown to increase with maize amount. The possibility to trace OGM presence in the fodder can be speculated on the same hypothesis, since transgenic fodder is mainly made up of soybean, a typical C3 plant, largely used in conventional zootechny. Conventional and organic (GMO free) milk samples were collected from the Italian market and analyzed for 13C/12C ratio of glycerol. A sample preparation from whole milk was set up, specifically targeted for GC-IRMS analysis. When compared to conventional milk, organic milk resulted in an enrichment in 13C (P < 0.02), showing a different diet regimen, rich in C4 plants, and therefore suggesting a GMO-free diet. These encouraging results can be combined with data deriving from the investigation of different isotope ratios, to assess also the geographical origin of the milk (e.g. no EU countries, with different GM regulations) and screening of milk for transgenic DNA presence
The detection of pseudo-endogenous androgenic anabolic steroids in sports by isotope ratio mass spectrometry: A global sample purification strategy
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Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Nandrolone metabolites in urine and doping control analysis: A procedure based on GC/C/IRMS analysis of both 19-norandrosterone and 19-noretiocholanolone
No full textMetabolism of boldione in humans by mass spectrometric techniques: detection of pseudoendogenous metabolites
No full textBoldione is an anabolic androgenic steroid (AAS) related to boldenone, androstenedione, and testosterone bearing two double bonds in C1 and C4 positions. Boldione is rapidly transformed to the well-known AAS boldenone, being both compounds included in the list of prohibited substances and methods published yearly by the World Anti-Doping Agency (WADA). After the administration of boldione to a male volunteer, the already described urinary metabolites of boldenone produced after reduction in C4, oxydoreduction in C3 and C17, and hydroxylation have been detected. In addition, minor new metabolites have been detected and their structure postulated after mass spectrometric analyses. Finally, the reduction of the double bound in C1 produces metabolites identical to the endogenously produced ones. A method based on gas chromatography coupled to isotope ratio mass spectrometry (GC/C/IRMS) after a urine sample purification by high performance liquid chromatography (HPLC) permitted to confirm the main synthetic like boldione/boldenone metabolite (17-hydroxy-5-androst-1-en-3-one) and boldenone at trace levels (< 5ng/mL) and then to establish its synthetic or endogenous origin, and to determine the exogenous origin of metabolites with the same chemical structure of the endogenous ones. The detection of pseudoendogenous androgens of synthetic origin partially overlapped boldenone and its main metabolite detection, being an additional proof of synthetic steroids misuse. By the use of IRMS, the correct evaluation of the modifications of the steroid profile after the administration of synthetic AAS that could be converted into endogenous like ones is possible. Copyright (c) 2013 John Wiley & Sons, Ltd
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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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