Atatrk University

Erzurum, Turkey

Atatrk University

Erzurum, Turkey
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Gocer H.,Atatrk University | Gulcin I.,Atatrk University | Gulcin I.,Agri Ibrahim Cecen University
International Journal of Food Sciences and Nutrition | Year: 2011

Caffeic acid phenethyl ester (CAPE), a plant polyphenolic concentrated in honeybee propolis, has been found to be biologically active in a variety of pathways. The aim of this study was to determine the antioxidant activity of CAPE using different methods such as total antioxidant activity by the thiocyanate method, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid radicals, 1,1-diphenyl-2-picryl-hydrazyl free radicals, N,N-dimethyl-p- phenylenediamine dihydrochloride radicals and superoxide anion radicals scavenging activities, reducing power and ferrous ions (Fe 2+) chelating activities. CAPE showed 97.9% inhibition on lipid peroxidation of linoleic acid emulsion. On the other hand, butylated hydroxyanisole, butylated hydroxytoluene, α-tocopherol and trolox indicated an inhibition of 87.3, 97.6, 75.3 and 90.3% on peroxidation in the same system, respectively. © 2011 Informa UK, Ltd.


Sara Y.,Atatrk University
Journal of Computational and Nonlinear Dynamics | Year: 2013

We get symbolic and numeric solutions developing a MAPLE program which uses the initial velocity on the state variable of a wave equation as control function. Solution of this problem implies the minimization at the final time of the distance measured in a suitable norm between the solution of the problem and a given target. An iterative algorithm is constructed to compute the required optimal control as the limit of a suitable subsequence of controls. Results are tested with some numerical examples. © 2013 American Society of Mechanical Engineers.


Emin Ozdemir M.,Atatrk University | Avci M.,Atatrk University | Kavurmaci H.,Atatrk University
Computers and Mathematics with Applications | Year: 2011

In this paper, we establish several new inequalities for functions whose second derivative in absolute value aroused to the qth(q<1) power are (α,m)-convex. Some applications to special means of positive real numbers are also given. © 2011 Elsevier Ltd. All rights reserved.


Patterson K.,California State University, San Marcos | Cakmak T.,California State University, San Marcos | Cakmak T.,Atatrk University | Cooper A.,California State University, San Marcos | And 3 more authors.
Plant, Cell and Environment | Year: 2010

Nitrogen is the only macronutrient that is commonly available to plants in both oxidized and reduced forms, mainly nitrate and ammonium. The physiological and molecular effects of nitrate supply have been well studied, but comparatively little is known about ammonium nutrition and its differential effects on cell function and gene expression. We have used a physiologically realistic hydroponic growth system to compare the transcriptomes and redox status of the roots of ammonium- and nitrate-supplied Arabidopsis thaliana plants. While ∼60% of nitrogen-regulated genes displayed common responses to both ammonium and nitrate, significant 'nitrate-specific' and 'ammonium-specific' gene sets were identified. Pathways involved in cytokinin response and reductant generation/distribution were specifically altered by nitrate, while a complex biotic stress response and changes in nodulin gene expression were characteristic of ammonium-supplied plants. Nitrate supply was associated with a rapid decrease in H2O2 production, potentially because of an increased export of reductant from the mitochondrial matrix. The underlying basis of the nitrate- and ammonium-specific patterns of gene expression appears to be different signals elaborated from each nitrogen source, including alterations in extracellular pH that are associated with ammonium uptake, downstream metabolites in the ammonium assimilation pathway, and the presence or absence of the nitrate ion. © 2010 Blackwell Publishing Ltd.


Gultekin L.,Atatrk University
Florida Entomologist | Year: 2012

Larvae of Conorhynchus hololeucus (Coleoptera: Curculionidae: Lixinae) construct a trehala-like capsule for the immature stages. The host plant is Atriplex sp. (Caryophyllales: Amaranthaceae), and this weevil species is a new record for Turkey. Adults feed on leaves; females lay eggs in root neck of host plants; larvae make an external trehala-like capsule on the root; pupation and adult emergence occur in the capsule. This weevil produces one generation per year.


Sonmez E.,Atatrk University | Meral K.,Atatrk University
Journal of Nanomaterials | Year: 2012

We have investigated correlation of photoluminescence lifetime between zinc oxide (ZnO) nanorods and thiourea-doped ZnO nanorods (tu: CH 4N 2S). Aqueous solutions of ZnO nanorods were deposited on glass substrate by using pneumatic spray pyrolysis technique. The as-prepared specimens were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and time-resolved photoluminescence spectroscopy (TRPL). The photoluminescence lifetime of ZnO nanorods and ZnO nanorods containing thiourea was determined as τ = 1.56 ± 0.05 ns (χ 2 = 0.9) and τ = 2.12 ± 0.03 ns (χ 2 = 1.0), respectively. The calculated lifetime values of ZnO nanorods revealed that the presence of thiourea in ZnO nanorods resulted in increasing the exciton lifetime. In addition to the optical quality of ZnO nanorods, their exciton lifetime is comparable to the longest lifetimes reported for ZnO nanorods. The structural improvement of ZnO nanorods, containing thiourea, was also elucidated by taking their SEM images which show the thinner and longer ZnO nanorods compared to those without thiourea. Copyright © 2012 Erdal Snmez and Kadem Meral.


Gltekin L.,Atatrk University | Korotyaev B.A.,Russian Academy of Sciences
Coleopterists Bulletin | Year: 2012

We present new data on the host plants, biology, and distribution of Cosmobaris discolor (Boheman, 1836) and Hypolixus pica (F., 1798) (Coleoptera: Curculionidae). Larval host plants are ascertained for the first time for both species in the eastern Mediterranean region of Turkey. Amaranthus spinosus L. and Amaranthus viridis L. (Amaranthaceae) are the host plants of C. discolor. Immature stages of C. discolor develop inside the main stem and lateral branches of both plants. Amaranthus spinosus is a host plant of H. pica, whose immature stages develop inside the root system. This is a new country record for C. discolor in Turkey.


Gur E.,Atatrk University | Gur E.,Ohio State University | Zhang Z.,Ohio State University | Krishnamoorty S.,Ohio State University | And 2 more authors.
Applied Physics Letters | Year: 2011

Schottky diode properties of semitransparent Ag(4 nm)/Au(4 nm) metal stack on In0.2Ga0.8N were investigated and defect characterization was performed using capacitance deep level transient (DLTS) and optical spectroscopy (DLOS). DLTS measurements made on the In 0.2Ga0.8N Schottky diodes, which displayed a barrier height of 0.66 eV, revealed the presence of two deep levels located at Ec-0.39 eV and Ec-0.89 eV with nearly identical concentrations of ∼1.2 10 15cm-3. Three deeper defect levels were observed by DLOS at Ec-1.45 eV, Ec-1.76 eV, and Ec-2.50 eV with concentrations of 1.3 10 15cm-3, 3.2 1015cm-3, and 6.1 1016cm-3, respectively. The latter, with its high trap concentration and energy position lying 0.4 eV above the valance band, suggests a possible role in compensation of carrier concentration, whereas the mid-gap positions of the other two levels imply that they will be important recombination-generation centers © 2011 American Institute of Physics.


Cho H.,University of Massachusetts Boston | Madden R.,University of Massachusetts Boston | Nisanci B.,University of Massachusetts Boston | Nisanci B.,Atatrk University | Torok B.,University of Massachusetts Boston
Green Chemistry | Year: 2015

A new, modified synthesis of pyrroles is described. The reaction of 2,5-hexandione with a variety of amines yielded the expected pyrrole analogues in excellent yields. The reactions were carried out under the ultimate green conditions excluding both catalyst and solvent applying simple stirring at room temperature. The variety of amines include aqueous ammonium hydroxide for the synthesis of pyrroles with a free NH group, and benzylamines, anilines and phenylene-diamines for the synthesis of several N-derivatized pyrroles. The reaction also occurs efficiently with a variety of 1,4-diketones, although the reaction rates and yields are lower for the diketones that do not possess terminal methyl group(s). This journal is © The Royal Society of Chemistry 2015.


Sarikaya M.Z.,University of Science and Arts of Iran | Set E.,Atatrk University | Ozdemir M.E.,Atatrk University
Computers and Mathematics with Applications | Year: 2010

In this paper, we establish some new inequalities of Simpson's type based on s-convexity. Some applications to special means of real numbers are also given. © 2010 Elsevier Ltd. All rights reserved.

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