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Essential oil from the leaves of Hibiscus surattensis L. from Nigeria
No full textThe phytochemical analysis of the essential oil obtained by hydrodistillation from the leaves of Hibiscus surattensis L. (Malvaceae) is being reported. The oil, analyzed by gas chromatography-flame ionization detector (GC-FID) and GC-mass spectrometry (GC-MS), was dominated by monoterpenes (34.1%) and sesquiterpene compounds (41.2%). The major oil constituents were β-caryophyllene (12.9%), menthol (10.6%), methyl salicylate (9.7%) and camphor (9.2%). There were significant amounts of germacrene D (5.5%), hexadecanoic acid (4.3%), α-humulene (4.0%), 1, 8-cineole (3.0%) and menthone (3.0%). This is the first report on the volatile compounds of H. surattensi
Essential Oil of Phyllanthus reticulatus Poiret from Nigeria
Get PDFThe chemical composition of the essential oil obtained by hydrodistillation from the leaves of Phyllanthus reticulatus Poiret (Euphorbiaceae) growing in Nigeria has been studied. The constituents of the oil were analyzed by means of gas chromatography (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). Monoterpenes (64.9%) were the dominant class of compounds, followed by sesquiterpenes (23.0%). The major constituents were α-pinene (6.0%), sabinene (7.6%), β-pinene (18.1%), linalool (6.9%) and camphor (7.7%), among the monoterpenes, and β-caryophyllene (11.9%) and germacrene D (8.6%) among the sesquiterpenes. This is
the first report on the volatile constituents of Phyllanthus reticulatu
Chemical compostion of the leaf oils of Croton zambesicus Müll.-Arg. grown in Lagos, South-West Nigeria
No full textThe chemical composition of the leaf essential oil of Croton zambesicus Müll.-Arg., collected from Agbara-Lagos, Nigeria, was analysed by means of Gas chromatography-flame ionization detector (GC-FID) and Gas chromatography coupled with Mass spectrometry (GC-MS). Sixty constituents accounting for 98.9% of the total oil contents were identified from the oil sample. The classes of compounds identified in the oil were monoterpene hydrocarbons (35.3%), oxygenated monoterpenes (22.9%), sesquiterpene hydrocarbons (32.4%) and oxygenated sesquiterpenes (5.6%). The oil was dominated by β-pinene (15.1%), β-caryophyllene (12.6%), germacrene D (10.9%), camphor (7.3%), linalool (7.0%), sabinene (6.4%) and α-pinene (5.2%).
Aims: The aim of the research is to investigate the volatile constituents from C. zambesicus harvested in Lagos, Nigeria.
Study Design: Extraction of essential oil from the air-dried leaf samples of C. zambesicus and investigation of its chemical constituents.
Place and Duration of Study: Leaf samples of C. zambesicus were collected from Agbara, Lagos, on April 2011.
Methodology: Air-dried and pulverized leaves were hydrodistilled in a Clevenger-type apparatus to obtained pale yellow volatile oil whose chemical constituents was analyzed by GC and GC/MS.
Results: A total of sixty compounds were identified, amounting to 98.9%of the total oil contents. The major were compounds β-pinene (15.1%), β-caryophyllene (12.6%), germacrene D (10.9%) and camphor (7.3%). Variations in compositional pattern were observed between this result and the previous studies.
Conclusion: The literature about the C. zambesicus indicates a high variability in the chemical composition of the essential oils
Volatile constituents and potatoes tuber sprout suppressant activity of Pimenta racemosa (Mill) J.W. Moore
No full textEssential oil was obtained by hydrodistillation from air dried aerial part of Pimenta racemosa (Mill) J.W: Moore. The oil was analysed for its constituents by means of gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). Sesquiterpene compounds (63.1%) occurred in higher proportion. The major consttuents of the oil were germacrene D (10.6%), β-elemene (8.8%), germacrene A (7.3%), selin-11-en-4-a-ol (6.3%), δ-cadinene (5,9%), β-caryophylene (5.8%), germacrene B (5.3%) and α-copaene (5.2%). The essential oil of Pimenta racemosa applied as dust formulation, was effective as a potato tuber sprout suppressan
A new chemical form of essential oil of Hyssopus officinalis L. (Lamiaceae) from Nigeria
No full textEssential oil obtained by hydrodistillation from the air-dried leaves of Hyssopus officinalis L. (Lamiaceae) collected in Ajangbadi area, West of Lagos, Nigeria, was analyzed comprehensively for its constituents by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The monoterpene hydrocarbons, α-pinene (70.9%) and β-pinene (10.9%) are the dominant constituents of the oil of H. officinalis. A cluster analysis was performed for comparison and characterization of H. officinalis essential oil from Nigeria with other oils reported in the literature from different locations across the world, and reveals chemical variation in this species with at least 8 different chemotypes. The compositional pattern of Nigerian oil sample was being reported for the first time and represents another chemotype of the oil of H. officinali
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
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
Chemical composition of Citrus limon (L.) Osbeck growing in southwestern Nigeria: essential oil chemotypes of both peel and leaf of lemon
Get PDFThe leaf and peel essential oils of Citrus limon, collected from the Agboku area of Ado-Odo Local government Area in Ogun state, Nigeria, were obtained by hydro distillation and analysed by GC-FID and GC-MS. The leaf oil was rich in limonene (31.5%), sabinene (15.9%), citronellal (11.6%), linalool (4.6%), neral (4.5%), and geranial (4.5%), while the peel essential oil was dominated by limonene (85.9%). A numerical cluster analysis of leaf and peel essential oils reported in the literature revealed three identifiable clusters of peel oil (a limonene chemotype and two mixed chemotypes, limonene/citral/β-pinene and limonene/linalool/linalyl acetate). The leaf essential oils fell into four clusters (limonene/citral/β-pinene, β-pinene/γ-terpenene, limonene/sabinene, and linalool/linalyl acetate). The leaf and peel essential oils from Agboku, Nigeria occupied the limonene/sabinene and the limonene chemotypes, respectively
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