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Erzurum, Turkey

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.

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.

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.

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.

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