1,720,974 research outputs found
Enantiomeric Separation of Amino-alcohols on Dinitrobenzoyl-diaminocyclohexane Chiral Stationary Phases
No full textA silica-bonded chiral stationary phase, containing the N,N'-3,5-dinitrobenzoyl derivative of 1R,2R-diaminocyclohexane, was used to separate the enantiomers of some amino alcohols with beta-blocking activity after their conversion to oxazolidin-2-ones. The influence of mobile phase composition (mixtures of hexane with dichloromethane, chloroform, dioxane and isopropanol) on the enantioselectivity and efficiency of the column was evaluated. Furthermore, a tandem arrangement of the chiral column and its racemic version was used to resolve all the stereoisomers of one amino alcohol containing two stereogenic centres
Direct High-performance Liquid-chromatography Resolution On Chiral Columns of Tiaprofenic Acid and Related-compounds In Bulk Powder and Pharmaceutical Formulations
No full textHigh-performance liquid chromatography (HPLC) was employed for the separation and determination of impurities [5-benzoyl-2-acetylthiophene (BAT), 5-benzoyl-2-ethylthiophene (BET) and (RS)-5-benzoyl-alpha-methyl-3-thiopheneacetic acid (3-isomer of tiaprofenic acid) contained in bulk racemic tiaprofenic acid and pharmaceutical formulations. Chiral columns containing the 3,5-dimethylphenylcarbamate of cellulose and amylose were used. The effect of the organic modifier, 2-propanol, in the mobile phase was studied. The HPLC method gave good performances from qualitative and a quantitative standpoints, allowing the enantiomeric ratios of tiaprofenic acid and its 3-isomer to be determined together with the related impurities BAT and BET
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
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
Direct HPLC enantioseparation of omeprazole and its chiral impurities: Application to the determination of enantiomeric purity of esomeprazole magnesium trihydrate
No full textAnalytical and semipreparative high-performance liquid chromatography (HPLC) enantioseparation of the proton-pump inhibitor omeprazole (OME) and its potential organic chiral impurities were accomplished on the immobilised-type Chiralpak IA chiral stationary phase (CSP) under both polar organic and normal-phase conditions The (S)-enantiomers were isolated with a purity of >99% cc and their absolute configuration was empirically assigned by circular dichroism (CD) spectroscopy. A chemo- and enantioselective HPLC method was validated to control the enantiomeric purity of the (S)-enantiomer of OME (ESO), an active ingredient contained in drug products, in the presence of chiral and achiral related substances The precision, linearity and accuracy of the determination of the (R)-impurity as well as the recovery of ESO from a pharmaceutical preparation were determined The proposed method uses the mixture methyl tert-butylether (MBE)-ethyl acetate (EA)-ethanol (EtOH)-diethylamme (DEA) 60 40 5 0 1 (v/v/v/v) as a mobile phase In these conditions, linearity over the concentration range 0 5-25 mu g/ml for (R)-enantiomer was obtained. The limits of detection and quantification were 99 and 333 ng/ml, respectively The intra and inter-day assay precision was less than 2% (RSD%). 2010 Elsevier B V All rights reserve
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
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
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