1,721,006 research outputs found
The chemical composition of the aerial parts’ essential oil of Limonium lobatum (L.f.) Chaz. growing wild in Algeria
No full textThe Limonium genus (Plumbaginaceae) includes several species of perennial herbs and shrubs belonging to a particular type of halophytes, known as 'recretohalophytes'. Limonium species are widely distributed in the Mediterranean region, mainly in the North-Eastern and Southern countries and several bioactivities have been well documented. In the present study, the chemical composition of the essential oil (EO) of the aerial parts of Limonium lobatum (L.f.) Chaz., a species never chemically previously studied and collected in Algeria, which grows in South Spain, North Africa, and SW Asia, was analysed using GC-MS. The main constituents of the EO were monoterpenes involving eucalyptol (14.21%), beta-pinene (8.62%), beta-myrcene (8.18%). Among the sesquiterpene compounds beta-caryophyllene (8.94%) was the major one. The chemical profile of the EO presented here was compared with the EOs of previously investigated Limonium taxa. Furthermore, a complete literature review on the ethno-pharmacological uses of Limonium species was performed.[GRAPHICS]
The chemical composition of the essential oils of two Mediterranean species of Convolvulaceae: Convolvulus althaeoides subsp. tenuissimus collected in Sicily (Italy) and Calystegia silvatica collected in Algeria
No full textConvolvulus L. and Calystegia R.Br. are two closely related genera of the Convolvulaceae family distributed in Asia, Mediterranean, Macaronesia, East Africa, and Arabia, including about 210 and 30 accepted species, respectively, of flowering plants, present as trees, shrubs, and herbs. The ethnomedical use of Convolvulus species dates to 1730s as they displayed profuse medicinal properties. In the present study, the not previously investigated chemical compositions of the essential oils from aerial parts of Convolvulus althaeoides subsp. tenuissimus (Sm.) Bat., collected in Sicily, and Calystegia sylvatica (Kit.) Griseb., collected in Algeria, were evaluated by GC-MS. The main components of the essential oil of the first one were β-caryophyllene (28.68%), γ-muurolene (23.75%), and γ-elemene (17.55%), whereas the C. silvatica essential oil was shown to be rich of valeranone (10.77%), viridiflorol (9.45%), and germacrene D (8.61%). Furthermore, a complete literature review on the ethno-pharmacological uses of Convolvulus and Calystegia species was performed
Phytochemical analysis of Clinopodium candidissimum (Munby) Kuntze growing in Algeria by an integrated HS-SPME-GC-MS, NMR and HPLC-DAD-MSn approach: valorisation of an endemic natural source of bioactive compounds
No full textClinopodium candidissimum (Munby) Kuntze (Lamiaceae) is used in traditional medicine and as a food condiment in Algeria, where it is known as Zaater cheleuh and Nabta elbida. Here, we report the comprehensive characterisation of non-volatile polar constituents extracted from C. candidissimum aerial parts (a mixture of inflorescences, stems and leaves), and their aroma profile. Qualitative H-1-NMR and quali-quantitative HPLC-MSn analyses of fractions obtained with solvents at different polarity revealed the presence of aglyconic and glycosylated flavonoids (3.1%), phenylpropanoids (3.6%), gallic acid derivatives (0.76%), and triterpenoids (0.62%), among the others. On the other hand, HS-SPME-GC-MS allowed to identify 38 volatile constituents, among which the oxygenated monoterpenes pulegone (44.8%), piperitenone (6.6%), isopulegone (5.8%) and neo-menthol (3.8%), and the sesquiterpene hydrocarbons germacrene D (16.2%) and bicyclogermacrene (3.0%) were the most abundant. Overall, results indicate that C. candidissimum represents an endemic natural source of antioxidants and bioactive compounds, and they will be useful for further studies on this species
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
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
- …
