1,720,989 research outputs found
Composition and antioxidant and antimicrobial activity of the volatile oils from Olea europaea L. fruit and stem
No full textThe aims of this study was to analyze the chemical composition of fruits and stem volatile oils of Olea europaea L. cv. Chemchali and to test the efficacy of volatile oils against four pathogenic bacteria and four phytopathogen strains and their antioxidant activity. The GC-MS analysis revealed 38 compounds representing 88.5 and 73.6% of the total oils containing 3-ethenylpyridine (12.5%), (E)-2-decenal (11.4%) and 2-ethylbenzaldehyde (7.7%) in fruit and nonanal (9.9%), (E)-2-decenal (9.6%) and benzyl alcohol (9.00%) in stem as major components, respectively. The antibacterial and antifungal activities of stem volatile oils were relatively good. Therefore, the stem of Olea europaea L. demonstrated higher activities against tested fungi and bacteria than the fruit. The DPPH and ABTS-radical-scavenging activities of the oils showed that the lowest EC50 value was detected in volatile oil from fruit
Effects of irrigation regimes on fatty acid composition, antioxidant and antifungal properties of volatiles from fruits of Koroneiki cultivar drown under Tunisian conditions
No full textThe olive tree is generally grown under rain-fed conditions. However, since the yield response to irrigation is great, even with low amounts of water, there is increasing interest in irrigated agriculture. The main goal of this study was, therefore, to investigate the effect of irrigation regimes on olive (Olea europaea L., cv. Koroneiki) obtained from an intensively-managed orchard in a semi-arid area with a Mediterranean climate in Tunisia. Different irrigation treatments 50% ETc, 75% ETc and 100% ETc were applied to the olive orchard. Accordingly, the effects of three irrigation regimes on volatile compounds, fatty acid composition and biological activities of Koroneiki cultivar were studied. The total profile of the volatile constituents of all samples revealed the predominance of 3-ethenylpyridine (from 14.9-19.6%), phenylethyl alcool (from 7.8-19.2%) and benzaldehyde (from 9.0 to 13.8%). During watering level treatments studied, the major fatty acids were oleic, palmitic and linoleic. Antioxidant activity of the fresh fruit volatiles cultivated at a watering level of 100% ETc was higher than that obtained under 50 and 75% Etc. The results of antifungal activity showed that the fruits volatiles of the three irrigation treatments had varying degrees of growth inhibition against the microorganisms teste
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
Fatty acid composition and biological activities of volatiles from fruits of two Tunisian olive cultivars
No full textThis study investigates volatile compounds, fatty acid composition and antioxidant, antibacterial and antifungal activities of fruits from two olive cultivars (Chemlali and Neb Jmel). Fatty acid profiles varied significantly between cultivars (cvs) where Neb Jmel seem to have higher contents of palmitic and oleic acids (16.4% and 66.4%, respectively) and lower of linoleic acid (9.4%). The volatile profile indicated the apparent difference between cvs. In fact, the main components detected in Chemlali cv. were (E,E)-2,4-decadienal (23.0%), (E,Z)-2,4-decadienal (14.9%) and nonanal (6.7%), while 3-ethenylpyridine (15.5%), (E)-2-decenal (14.4%) and (E)-2-undecenal (7.0%) were the major components in Neb Jmel cv. Furthermore, these volatiles were subjected to screening for their possible antioxidant activities where volatiles from Neb Jmel fruits were found to be better. Results presented here may suggest that the volatiles fraction of two cultivars possess antimicrobial and antifungal activities
Study of chemical composition, antibacterial and antioxidant activities of Rapistrum rugosum L. essential oils from flowers, leaves, and stems
Full text linkThe chemical composition of the essential oils of three organs (flowers, leaves and stems) from Rapistrum rugosum (L.) All., was studied and screened for their possible antibacterial and antioxidant properties. According to the GC and GC/ MS analysis, 28 (represent 92.5 % of the total oil composition), 23 (93.9 %), and 38 compounds (94.3 %) were identified from flowers, leaves and stems, respectively. The major compound in the leaves essential oil was found to be pentadecanal (55.3 %) followed by hexahydrofarnesylacetone (8.4 %) and tetradecanoic acid (5.7%). While hexahydrofarnesylacetone (17.2 %) followed by 1-pentadecanol (8.3 %), tetradecanoic acid (5.9 %), (E)-β-damascenone (5.7 %) were the major compounds of the flowers oil. Tetradecanoic acid (13.1 %), hexahydrofarnesylacetone (10.1 %), dodecanoic acid (10.0 %), isobornyl acetate (7.6 %), 5- methylthiopentyl isothiocyanate (6.7 %) and (E)-β-ionone (6.2 %) were the main constituents for the stem essential oil. The essential oil of flowers exhibited the higher activity in each antioxidant system (ABTS, DPPH and β-Carotene-linoleic acid methods) with an important value for DPPH assay (PI = 69.88 ± 0.02 %). Furthermore, the isolated oils were tested against five Gram-positive and Gram-negative bacteria. It was found that the essential oil of all organs exhibited interesting antibacterial activities against Gram-positive bacteria, comparable to those of Gentamicin, which was used as positive control
Aroma volatile components, fatty acids and antibacterial activity of four Tunisian Punica granatum L. flower cultivars
No full textThis study investigates the varietal effects on volatile components and fatty acids composition (analysed by GC–MS and GC, respectively) as well as the antibacterial propriety (using microdilution test) from four Tunisian pomegranate flower cultivars (Tounsi, Nabli, Gabsi and Chelfi). The Chelfi flowers seemed to be the richest in terpenoids (28.39%), aldehydes (13.24%) and alcohols (22.30%). Those volatiles seemed to be the most important groups with apparent difference between varieties. Fatty acid profiles varied significantly among cultivars. The most abundant saturated fatty acid was palmitic acid where Nabli cultivar exhibited the highest amount (435.80 μg/g). However, Gabsi cultivar had the highest content of unsaturated fatty acids where the linolenic acid and linoleic acid were the most frequent polyunsaturated fatty acids with 254.42 and 707.73 μg/g, respectively. Results presented here may suggest that the volatiles fraction of the studied cultivars possess antimicrobial activities. This work gives further knowledge for extensive development of this medicinal plan
Chemical composition and biological activities of volatile fractions from three Tunisian cultivars of olive leaves
No full textThe chemical composition, antibacterial, and antifungal activities of the volatile fractions from fresh and dried leaves of three Olea europaea L. cultivars from Tunisia (Neb jemel, Chemchali and Chemlali) have been studied. The volatile components were obtained via hydrodistillation and analyzed by GC–MS. The major constituents were (E)-3-hexenol, 3-ethenylpyridine, (E)-β-damascenone and phenylethyl alcohol, but their percentages varied according to the treatment of the leaves. Antioxidant activities were determined applying DPPH and ABTS+ radical-scavenging assays. In general, antioxidant activity of the volatile fraction obtained from fresh leaves was superior to that obtained from dried leaves. The antibacterial and antifungal activities of the volatile fractions from fresh and dried leaves were evaluated against four bacterial and four fungal strains. The volatile fractions showed significant antibacterial and antifungal effects. However, some differences were observed in the response for several microorganisms, because of the variability of the composition. This work gives further knowledge for extensive development of this medicinal plan
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