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Van, Turkey

Akin C.,Middle East Technical University | Akin C.,Yuzuncuyil University | Bilgin M.,University of Illinois at Urbana - Champaign | Can Bilgin C.,Middle East Technical University
Amphibia Reptilia | Year: 2010

The water frog form caralitana was first described as a subspecies of Rana ridibunda by Arikan (1988) from southwestern Turkey. Its orange ventral colour has been used as a diagnostic character since its description. After testing for a correlation between body size and ventral colour, we compared mtDNA and venter colour of adult specimens from 27 localities to assess the validity of this character for systematics of Anatolian water frogs. We mapped the distribution of each category and tested whether there is concordance between mtDNA haplotype and ventral colour of sampled individuals at the watershed level. Furthermore, we analyzed relationships between ventral colour and altitude. Size and ventral colouration were found to be significantly correlated. The distribution of orange ventral colour exhibited a complex clinal variation especially west of the Lake District where different coloured individuals are seen syntopically. In other regions, there were abrupt changes, presumably because of geographic barriers such as mountains. Our results indicate that although there is significant concordance between caralitana-specific mtDNA and orange venter colour, there are certain watersheds where the majority of sampled individuals exhibits discordance in mtDNA and ventral colouration. In all periphery regions, some degree of genetic introgression is indicated. These patterns clearly indicate gene flow between the caralitana lineage and non-caralitana lineages and is supported by lack of evidence for habitat-specific selection, the assignment of individuals from the same population into distinct clades, and the occurrence of an intermediate character between different forms in transition zones. © Koninklijke Brill NV, Leiden, 2010. Source


Menges N.,Middle East Technical University | Menges N.,Yuzuncuyil University | Balci M.,Middle East Technical University
Synlett | Year: 2014

A series of alkenes and alkynes was subjected to reduction with hydrazine hydrate in ethanol in the presence of oxygen. An efficient method was developed for the reduction of C-C double bonds and C-C triple bonds with diimide, generated in situ from hydrazine hydrate by oxidation with oxygen. The reduction process proceeded for 24-48Â hours with high chemoselectivity and excellent yields. This reduction procedure offers synthetic advantages over metal-catalyzed hydrogenation as well as other systems. © Georg Thieme Verlag Stuttgart New York. Source


Erdil B.,Yuzuncuyil University | Erdil B.,Middle East Technical University | Akyuz U.,Middle East Technical University | Yaman I.O.,Middle East Technical University
Materials and Structures/Materiaux et Constructions | Year: 2012

This study aims to present the mechanical behavior of carbon fiber reinforced polymers (CFRP) reinforced low strength cylindrical and prism concrete specimens under both heating-cooling cycles and sustained loading. Heating-cooling cycles range from -10 to 50°C and the applied sustained load level is 40% of the ultimate strength of concrete. After 200 heating-cooling cycles and/or sustained load testing, specimens were tested to determine the mechanical behavior under uniaxial compression. The experimental test results show that heating-cooling cycles alone have insignificant effect on the mechanical properties of CFRP-wrapped specimens. However, as for simultaneous exposure of sustained loading and heating- cooling cycles the main difference is on the shape of the stress-strain diagram, in which the bilinear response becomes clear. The other difference is on the ultimate strain, which decreases up to 29 and 15% for cylindrical and prismatic specimens, respectively. © RILEM 2011. Source


Gulcan M.,Yuzuncuyil University | Sonmez M.,University of Gaziantep | Berber I.,Sinop University
Turkish Journal of Chemistry | Year: 2012

A new Schiff base, {1-[(5-bromo-2-hydroxy-benzylidene)-amino]-4-phenyl-2- thioxo-1,2-dihyro-pyrimidin-5-yl}-phenyl-methanone, was synthesized from N-amino pyrimidine-2-thione and 5-bromsalicylaldehyde. Metal complexes of the Schiff base were prepared from acetate salts of Cu(II), Ni(II), Co(II), Pd(II), and PtCl 2 in methanol. The chemical structures of the Schiff base ligand and its metal complexes were confirmed by spectroscopic analysis. All of the compounds were evaluated for their antimicrobial against 4 grampositive bacteria, 1 gram-negative bacterium, and 3 yeast strains. The Schiff base and the Cu(II) and Co(II) complexes showed good biological activity against all tested bacteria and yeast strains. © TÜBITAK. Source


Gulcin I.,Ataturk University | Huyut Z.,Yuzuncuyil University | Elmastas M.,Gaziosmanpasa University | Aboul-Enein H.Y.,National Research Center of Egypt
Arabian Journal of Chemistry | Year: 2010

Tannic acid, a naturally occurring plant polyphenol, is composed of a central glucose molecule derivatized at its hydroxyl groups with one or more galloyl residues. In the present paper, we examines the in vitro radical scavenging and antioxidant capacity of tannic acid by using different in vitro analytical methodologies such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH{radical dot}) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination using by Fe3+-Fe2+ transformation method, superoxide anion radical scavenging by riboflavin-methionine-illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe2+) chelating activities. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant radical scavenger compounds. Tannic acid inhibited 97.7% lipid peroxidation of linoleic acid emulsion at 15 μg/mL concentration. On the other hand, the above mentioned standard antioxidants indicated an inhibition of 92.2%, 99.6%, 84.6% and 95.6% on peroxidation of linoleic acid emulsion at 45 μg/mL concentration, respectively. In addition, tannic acid had an effective DPPH{radical dot} scavenging, ABTS{radical dot}+ radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, Fe3+ reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and trolox as references antioxidant compounds. The present study shows that tannic acid is the effective natural antioxidant component that can be used as food preservative agents or nutraceuticals. © 2009. Source

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