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Evaluation of Phenolic Compounds Quantity and Antioxidant Properties in Melissa officinalis L. Leave Extracts
No full textThe topic: Evaluation of Phenolic Compounds Quantity and Antioxidant Properties in Melissa
officinalis L. leave Extracts.
Keywords: lemon balm, total phenolic compounds, antioxidant activity, spectrophotometry, extracts.
The relevance of the topic: Natural antioxidants protect the human body from free radicals and prevents
certain diseases. For more than 2000 years this plant has been used to relieve and treat mental disorders.
Melissa officinalis L. contains phytocomponents such as flavanoids, phenolic acids with high antioxidant
activity and is responsible for ROS neutralization.
The problem of the research: How does the total amount of phenolic compounds and antioxidant
activity changes in lemon balm leave extracts?
The object of the research: Total phenolic compounds content and antioxidant activity in lemon balm
leave extracts.
The aim of the research: To compare the total amount of phenolic compounds and antioxidant activity
in lemon balm leave extracts.
Objectives of the research: 1. Describe the morphology of biologically active substances and the
pharmaceutical significance of the lemon balm leave (Melissa officinalis L.). 2. Isolate aqueous extracts
of lemon balm leave under different extraction conditions. 3. Compare the total amount of phenolic
compounds in the extracted lemon balm leave extracts using spectrophotometric analysis methods. 4.
Evaluate antioxidant activity of the obtained medicinal lemon balm leave extracts using DPPH reagent.
Research methods: During the theoretical research method, scientific sources are analyzed, the aim of
which is to get acquainted with the biologically active compounds accumulated in lemon balm leave.
Methods used in the study: production of aqueous extracts and ultrasonic extraction. Spectrophotometric
methods are used to evaluate the total phenolic content and antioxidant activity in vitro. Data were
processed using ,,MS Excel 2013’’ and ,,IBM SPSS 20.0’’.
Research results: The largest total amount of phenolic compounds was determined (16.95 mg GRE /
ml) by ultrasonic extraction for 60 minutes using purified water as solvent. The lowest total amount of
phenolic compounds was found (6.30 mg GRE / ml) in the aqueous extract prepared over a period of 15
minutes using boiling purified water as the extractant. The highest antioxidant activity was found in the
60-minute interval (75.00%) prepared in the aqueous extract. The lowest antioxidant activity was
determined in the extract by ultrasound for 15 minutes (17.52%) using an aqueous 10% PEG400 solvent.Darbo tema: Bendro fenolinių junginių kiekio ir antioksidacinio aktyvumo vertinimas vaistinės melisos
(Melissa officinalis L.) lapų ekstraktuose.
Raktiniai žodžiai: vaistinė melisa, bendras fenolinių junginių kiekis, antioksidacinis aktyvumas,
spektrofotometrija, ekstraktai.
Temos aktualumas: Natūralūs antioksidantai apsaugo žmogaus organizmą nuo laisvųjų radikalų ir
padeda užkirsti kelią tam tikroms ligoms. Daugiau nei 2000 metų šis augalas yra naudojamas lengvinti
ir gydyti psichikos sutrikimus. Melissa officinalis L. turi tokius fitokomponentus kaip flavanoidai,
fenolinės rūgštys, kurių antioksidacinis aktyvumas yra aukštas ir atsakingas už ROS neutralizavimą.
Tyrimo problema. Kaip kinta bendras fenolinių junginių kiekis ir antioksidacinis aktyvumas vaistinės
melisos lapų ekstraktuose?
Tyrimo objektas. Bendras fenolinių junginių kiekis ir antioksidacinis aktyvumas vaistinės melisos lapų
ekstraktuose.
Tyrimo tikslas. Palyginti bendrą fenolinių junginių kiekį ir antioksidacinį aktyvumą vaistinės melisos
lapų ekstraktuose.
Tyrimo uždaviniai: Aprašyti vaistinės melisos (Melissa officinalis L. ) morfologiją, biologiškai aktyvias
medžiagas ir farmacinę reikšmę. Išskirti vaistinės melisos vandeninius ekstraktus, taikant skirtingas
ekstrakcijos sąlygas. Palyginti bendrą fenolinių junginių kiekį išskirtuose vaistinės melisos ekstraktuose
taikant spektrofotometrinės analizės metodus. Įvertinti gautų vaistinės melisos ekstraktų antioksidacinį
aktyvumą naudojant DPPH reagentą.
Tyrimo metodika: Teorinio tyrimo metodo metu analizuojami moksliniai šaltiniai, kurių tikslas
susipažinti su vaistinės melisos kaupiamais biologiškai aktyviais junginiais. Tyrimui taikomi metodai:
vandeninių ištraukų gamyba ir ultragarsinė ekstrakcija. Atliekami spektrofotometriniai analizės metodai,
norint įvertinti bendrą fenolinių junginių kiekį ir antioksidacinį aktyvumą in vitro. Duomenys apdoroti
,,MS Excel 2013 m’’ ir ,IBM SPSS 20.0” programomis.
Pagrindiniai empirinio tyrimo rezultatai: Didžiausias bendras fenolinių junginių kiekis buvo
nustatytas (16,95 mg GRE/ml), taikant ultragarsinę ekstrakciją 60 minučių kaip tirpiklis naudotas
išgrynintas vanduo. Mažiausias bendras fenolinių junginių kiekis buvo nustatytas (6,30 mg GRE/ml)
vandeninėje ištraukoje, ruoštoje 15 minučių intervale kaip ekstrahentas naudotas verdantis išgrynintas
vanduo. Didžiausias antioksidacinis aktyvumas nustatytas vandeninėje ištraukoje, ruoštoje 60 minučių
intervale (75,00%). Mažiausias antioksidacinis aktyvumas nustatytas ekstrakte, taikant ultragarsą 15
minučių (17,52%) kaip naudotas vandeninis 10% PEG400 tirpiklis
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
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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