1,720,957 research outputs found
Angelica sylvestris L. (Apiaceae) of the Isle of Skye (Scotland): chemical composition of essential oil from the aerial flowering parts
No full textAngelica is a large genus of plants belonging to the Apiaceae family that includes about 100 species of biennial or perennial herbs. Several species of this genus are extensively used in various traditional medicines and, despite their content in toxic furanocoumarins, also as food. In this study, the chemical composition of the essential oil (EO) from aerial flowering parts of Angelica sylvestris L., a plant distributed in Europe, North and Central Asia, collected in the Isle of Skey (Scotland), was analyzed by GC and GC-MS. No one report has been previously published on this accession. The result showed the presence of a large quantity of monoterpene hydrocarbons with limonene (51.89%), by far, as the most abundant component. Other metabolites present in lesser quantity were β-pinene (4.61%), α-pinene (3.54%), and thymol (3.33%). Considerations with respect to all the other EOs of A. sylvestris taxa, studied so far, were carried out
Heracleum sphondylium L. subsp. sphondylium (Apiaceae) of the Isle of Skye (Scotland): the chemical composition of essential oil from the flowering aerial parts
No full textHeracleum is a large genus of plants belonging to Apiaceae family that includes about 90 species of biennial or perennial herbs. Several species of this genus are extensively used in various traditional medicines and, despite their content in toxic furanocoumarins, also as food. In the present study the chemical composition of the essential oil (EO) from flowering aerial parts of Heracleum sphondylium L. subsp. sphondylium, a plant distributed in Europe and North-West Africa, collected in the Isle of Skye (Scotland), was analyzed by GC and GC-MS. No one report has been previously published on any British accession. The result showed the presence of large quantity of sesquiterpene hydrocarbons and aliphatic esters, with bicyclogermacrene (31.6%) and octyl acetate (29.5%), by far, as the most abundant components. Considerations with respect all the other EOs of H. sphondylium taxa, studied so far, were carried out
collected in the Negev Desert (Israel)
No full textThe genus Phagnalon Cass. (Asteraceae) is widely distributed from Macaronesia in the West to the Himalayas in the East, from South France and Nord Italy to Ethiopia and Arabian Peninsula. Species of this genus have been used in folk medicine of many countries as medicinal herbs and they are also used such as food. The extracts and the essential oils (EOs) of these plants have reported antimicrobial, antioxidant, antidiabetic, antitumor, etc. properties and they have different biological applications. Phagnalon sinaicum Bornm. and Kneuck. is a very rare plant native of Middle East. It grows primarily in the desert or dry scrubland biome. Its EO, never previously investigated, was analysed by GC-MS. The EO was very rich in oxygenated monoterpenes, with artemisia ketone (20.40%), a-thujone (19.36%), and santolina alcohol (13.29%) as main constituent. Some considerations with respect to all the other EOs of Phagnalon taxa studied so far were carried out
Chemical composition, antimicrobial, and antioxidant activities of Opuntia stricta (Haw.) Haw. mucilage collected in Sicily, Italy
No full text: In this work the mucilage obtained from the cladodes of a not previously investigated accession of Opuntia stricta (Haw.) Haw. (syn. Opuntia dillenii (Ker-Gawl) Haw), collected in Sicily, was analysed by 13C-NMR. The yield of mucilage extracted from cladodes in aqueous medium was 2.55%. The monosaccharides identified, after acidic hydrolyses of the mucilage, were arabinose (36.48%), galactose (32.31%), xylose (15.33%), glucose (10.45%) and rhamnose (5.40%). The mucilage showed a sufficient antimicrobial activity and excellent antioxidant property
Opuntia ficus-indica (L.) Mill. and Opuntia stricta (Haw.) Haw. Mucilage-Based Painting Binders for Conservation of Cultural Heritage
Full text linkThe possibility of using materials from the waste of agricultural products for the conserva- tion of cultural and artistic heritage has led to important technological developments on mortars, plasters, colors, and other applications. In this experimental work, we investigated the binding properties of mucilage obtained from two different species of the genus Opuntia, both collected in Sicily, Italy: Opuntia ficus-indica (L.) Mill. and Opuntia stricta (Haw.) Haw. Through chemical acid hydrolysis, and subsequent spectroscopic analysis conducted at 13C-NMR, the main monosaccharide composition of both mucilage was studied, identifying considerable compositional differences. In fact, the mucilage of O. ficus indica had similar total amounts of arabinose (23.65%), galactose (20.87%), and glucose isomers (23.89%), while that of O. stricta was characterized by significant amounts of arabinose (36.48%) and galactose (32.31%) units. The samples were obtained by dispersing pigments on the mucilage and applying the obtained tempera by a brush onto both paper and chalk supports, in order to observe if the colors changed with different substrates. Colorimetric analysis, measuring ∆E, showed how the same pigment modifies its aspect depending on the binder used. After a two-week UV ageing process, pigments that had dispersed in O. stricta changed their aspect more than those dispersed in O. ficus-indica. Overall, it is also evident how ∆E data for organic pigments are higher than those for inorganic ones
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
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