1,720,965 research outputs found
Characterization of antioxidant properties of strawberry tree (Arbutus unedo L.) and trace elements determination
No full textStrawberry tree (Arbutus unedo L.) is a species that generally grows in the Mediterranean region and coasts and has been consumed as food since ancient times. Its fruits are mostly used in alcoholic beverages and various jams and desserts. Its fruits and leaves contain different phenolic compounds, because of this it is used in traditional folk medicine. They have different biological properties like, anti-diabetic, anti-inflammatory, urinary antiseptic, anti-hypertension, astringent, anti-diarrheal due to their high quantity of tannins. In this study, we aimed that to determine the total antioxidant capacity of fruits and leaves and trace element contents of Arbutus unedo L. which were collected in Yalova (TURKEY). The antioxidant activities of samples were examined by ferric reducing/antioxidant power (FRAP) method, cupric reducing antioxidant capacity (CUPRAC) method and trolox equivalent antioxidant capacity (TEAC) assay with ABTS radical cation. In the samples of the amount of total phenolic and tannins contents were determined using the Folin-Ciocalteu reagent (FCR) method. In adddition to, we determined the concentrations of Al, Cd, Cu, Cr, Fe, Mn, Pb, Zn in the samples by using ICP-MS. As a result, Arbutus unedo L. is a good source of antioxidants and minerals, it was stated that single antioxidant activity test would present limited information about the power of the antioxidant capacity and it was emphasized that use of combination of various methods should be used in assessing the antioxidant activities in vitro. It has been determined that the trace elements are within the determined limits
Development of spectrophotometric determination method for Au(III) and Ag(I)
No full textIn this research, a potentiometric and spectrophotometric method was developed to determine Ag(I) and Au(III) based on their reaction with m and p-phenylenediamine. As a result reactions between Ag(I) and Au(III) and m-and p-phenylenediamine mixtures was revealed that, there is an oxidation by means of complexation via oxidation, a diazo compound occured from amines and Ag(I) was reducted to elementel form, Au(III) was reducted to Au(I). Also the formation conditions of the reactions of these metals with amines were investigated, the pH range that the reactions took place, time needed for the formation of the reactions and the mol ratios needed for the complete reaction of the metals with amines. Mole ratios were determined as follows: Ag(I) / (m+p) phenylenediamine= 1; Au(III) / (m+p) phenylenediamine= 1/
ALUMINIUM(III), Fe(II) COMPLEXES AND DYEING PROPERTIES OF APIGENIN (5,7,4 '-TRIHYDROXY FLAVONE)
No full textApigenin and its metal complexes are used extensively in chemistry, biology and the dye industry. In this study, the interactions of flavonoids with metal ions and dyeing properties of these complexes are studied and these complexes of apigenin with aluminium and iron are examined by spectrophotometric and potentiometric methods. The stability constants of these complexes were determined potentiometrically. The evaluated protonation constants of the apigenin were found: logK(1) = 8.21 and logK(2) = 2.83 at the 25 degrees C. Logarithms of the stability constants were found: for aluminium complex: logK(1) = 8.24, logK(2) = 7.46, and logK(3) = 7.04 and for iron complex: logK(1) = 7.52, logK(2) = 5.80, and logK(3) = 5.00 at the 25 degrees C. The components of metal-apigenin complexes are given: 1:3 (metal: apigenin ratio) both Al(III) and Fe(II) from the results. According to our work; it can be said that Al(III) apigenin and Fe(II) apigenin complexes are formed in the dyeing process and this increases the lightfastness of the dyeing
Aluminium(III), Fe(II) Complexes and Dyeing Properties of Apigenin(5,7,4 '-trihydroxy flavone)
No full textApigenin and its metal complexes are used extensively in chemistry, biology and dye industry. In this study, the interactions of flavonoids with metal ions and dyeing properties of these complexes are studied and the complexes of apigenin with aluminium and iron are examined by spectrophotometric and potentiometric methods. The evaluated protonation constants of the apigenin were found: logK(1) = 8.21 and logK(2) = 2.83 at the 25 degrees C. Logarithms of the stability constants were found: for Aluminium complex : logK(1) = 8.24, logK(2) = 7.46, and logK(3) = 7.04 and for Iron complex : logK(1) = 7.52, logK(2) =5.80, and logK(3) = 5.00 at the 25 degrees C. The stoichiometry of metal-apigenin complexes are given 1:3 (metal: apigenin ratio) 100 both Al(III) and Fe(II) from the results. According to our works; it can be said that Al(III) -apigenin and Fe(II)- apigenin complexes are formed the dyeing process and this increases the lightfastness of the dyeing
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
Determining stability constants of naringenin (4',5,7-trihydroxy flavanone) complexes with aluminium (III) and iron (II) by potentiometric and spectrophotometric methods
No full textNaringenin and its metal complexes are used extensively in chemistry, biology and dye industry. In this study, complexes of naringenin with aluminium and iron are examined by spectrophotometric and potentiometric methods. The stability constants of these complexes were determined potentiometrically by using Calvin-Bjerrum and Irving Rossotti methods. The evaluated protonation constants of the naringenin were found: logK(1),= 10.19, logK(2) = 8.31, and logK(3) = 7.06 at the 25 degrees C. Logarithms of the stability constants were found: for Aluminium complex : logK(1)= 15.39 logK(2) = 7.12, and logK(3)= 6.47 and for Iron complex : logK(1)= 10.11, logK(2)= 6.40, and logK(3) = 6.11 at the 25 degrees C. The components of metal-naringenin complexes are given 1:3 (metal: naringenin ratio) both Al(III) and Fe(II) from the results
Determination of heavy metals in herbal teas marketed in Istanbul
No full textHerbal teas are being used pretty much in Turkey. Besides having a lot of beneficial speciality, teas carry heavy metals in their structure and heavy metal pollution increase with environmental pollution. In this study; sage, rosemary, St. John'swort, linden, mint, thyme, chamomile, fennel, green tea, blueberries were used and lead and cadmium metals in this teas which were bought from herbalist, have been researched with Atomic Absorption Spectrophotometer. According to the results, cadmium and lead concentrations in all dried samples have been found in the limits of Turkish Food Codex
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