1,720,979 research outputs found
DEVELOPMENT OF SPECTROPHOTOMETRICAL ASSAY FOR THE STUDY OF THE INTERACTION OF ANTIOXIDANT STANDARDS WITH 1,1-DIPHENYL-2-PICRYLHYDRAZYL FREE RADICALS
No full textThe aim of the present study was to develop a spectrophotometric based assay for the determination of binding parameters like binding constant and binding free energy of the free and 1,1-diphenyl-2-picrylhydrazyl (DPPH) bound forms of a set of antioxidant standards (AS). The determination of binding constant and binding free energy is based upon the decrease in absorbance of the electronic absorption spectrum of a 10-4 M acetonitrile solution of DPPH in the presence of a given concentration of a solution of antioxidant standards in the same solvent
THE EFFECT OF SOXHLET AND ULTRASONIC-ASSISTED EXTRACTION ON ANTIOXIDANT COMPONENTS AND ANTIOXIDANT PROPERTIES OF SELECTED SOUTH ALGERIAN RED POTATOES CULTIVARS
No full textThe present work aimed to study the effect of two different commonly applied extraction techniques for the evaluation of total phenolic contents (TPC), total flavonoid contents (TFC) and total antioxidant capacity (TAC) of fresh south Algerian red potatoes cultivars (Solanum tuberosum L). These techniques are namely Soxhlet extraction (SE) and ultrasonic-assisted extraction combines with maceration (UAE-M) for 5 min, 2 hours and 24 hours. A 40 kHz probe was used for the sonication at 3 different amplitudes (30 %, 50 %, and 70 %) with a mixture of ethanol/water at ratios of 70:30 and 100 % v/v as solvent. TPC and TFC obtained using SE are respectively 13.94 mg gallic acid equivalents (GAE) / g extract and 11.32 mg rutin equivalents (RE) / g extract, the amount of these contents is increased to 22.29 mg GAE / g extract and 85.93 mg RE / g extract using UAE-M with 100 % ethanol at amplitude 30 % and 24 hours maceration time. HPLC analysis of samples extract shows four contents with different concentration. In addition, all the results demonstrate a statistically significant with (p < 0.001). It should be noted that the use of UAE-M proved to be faster and more efficient process when compared to Soxhlet extraction
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
EXTENSION OF REKKER METHOD FOR THE PREDICTION OF NOCTANOL / WATER COEFFICIENT OF FERROCENE DERIVATIVES
No full textOctanol/water partition coefficients logP of many selected substituted ferrocenes were predicted by calculation for thefirst time using the fragmental Rekker method. The calculated values of logP were compared with the experimentalvalues. For estimation of the logP of the selected substituted ferrocenes, the average absolute error of logP is 0.08.Although the obtained values of logP by the proposed method are all very close to the experimental values, the valuesof logP obtained for ferrocene derivatives that do not contain a bulky group in their structure were significantly betterthan the results obtained for those containing a bulky group
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
PHYSICOCHEMICAL AND BIOCHEMICAL PROPERTIES OF HONEY BEE PRODUCTS IN SOUTH ALGERIA
No full textThe aim of the present study was to characterize the physical, biochemical and antioxidant properties of south Algeria honey samples (n = 5). Physical parameters, such as pH, moisture content, electrical conductivity, total dissolved solids, color intensity, total sugar content were measured. Several biochemical and antioxidant tests were performed to determine the antioxidant properties of the honey samples. The mean pH was 4.54, and moisture content was 14.88 %. The mean electrical conductivity was 0.597 mS∙cm-1, and the mean total dissolved solid was 0.14 % and the mean color was 163.6 mm Pfund. The mean total sugar contents was 82.76 %. High mean values of phenolic and flavonoid contents were respectively 697.22 mg GAE∙kg-1 and 290.70 mgREE∙kg-1. Antioxidant activity was also measured using DPPH assays, value of 26.19 mg∙mL-1 was detected for south Algeria (El-Oued) honey
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