1,720,960 research outputs found
Occurrence and determination of herbicides and their major transformation products in environmental waters
No full textA method for the simultaneous determination of selected maize and grain herbicides (amidosulfuron, N-([{[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl}amino)sulfonyl]-N-methylmethanesulfonamide; bentazone, 3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one2,2-dioxide; 2,4-D, (2,4-dichlorophenoxy)acetic acid; MCPA, (4-chloro-2-methylphenoxy)acetic acid; metosulam, N-(2,6'-dichloro-3-methylphenyl)-5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide) and their transformation products (TPs) (8-hydroxybentazone, 1H-2,1,3-benzothiadiazin-4(3H)-one,8-hydroxy-3-(1-methylethyl)-2, 2-dioxide; bifenox acid, 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid; clodinafop acid; 2,4-dichlorophenol; 4-chloro-2-methylphenol) in environmental waters was developed. The procedure combines a solid-phase extraction (SPE) with column liquid chromatography-tandem mass spectrometry detection utilizing a pneumatically assisted and heat-assisted electrospray interface in negative mode. The extraction of analytes from filtered drainage or river water samples was performed using as sorbent a graphitized carbon. The recovery, for drinking water, ranged from 91 to 98%, and from 84 to 95% for river water. Excellent method precision was demonstrated with percent relative standard deviation of less than 10% for all analytes at fortification level. Detection limits were at level of few nanograms per liter, except for 2,4-dichlorophenol and 4-chloro-2-methylphenol, that was in the range of tens of nanogram per liter. The present methodology was used for searching in river and drainage waters of maize-grain fields of the Tiber valley, during a typical period of herbicides application from April to July 2001. The levels detected of four compounds were in the range of: non-detectable (ND)-6.1, ND-27, ND-1.9 and ND-0.5 mug l(-1), for MCPA, bentazone, 8-hydroxybentazone and 2,4-D, respectively. Detectable amounts of bentazone-8-hydroxy at level of 0,3 mug l(-1) was found to be transported into river. The highly satisfactory results for all target analytes demonstrate the potential of liquid chromatography-tandem mass spectrometry for the identification and the quantification of the polar and acidic herbicides at below 100 ng l(-1) levels. (C) 2002 Elsevier Science B.V. All rights reserved
Determination of chemical compositions of essential oils by GC-MS analysis related with inhibition of microorganisms in food
No full textMicrobial contamination is a serious problem in food safety, which can lead to
spoilage of food products and/or cause health problems for consumers, so alternative sources of
safe, effective natural antimicrobial compounds could be a useful tool. Some essential oils have
shown antibacterial activity but seldom the synergic effects of EO combinations have been
investigated. In this work the chemical composition of five EOs was investigated: the
identification of the analytes was carried out by means of a double GC-MS analysis matching
the spectra with the NIST Library, while semi-quantitative analysis has been carried out by
means of GC-FID
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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