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Öğe Design, preparation and application of a Pirkle-type chiral stationary phase for enantioseparation of some racemic organic acids and molecular dynamics studies(ACG Publications, 2017-11) Çakmak, Reşit; Ercan, Selami; Sünkür, Murat; Yılmaz, Hayrullah; Topal, GirayThis study consists of two parts. In the first part of the study; a Pirkle-type chiral stationary phase was prepared by synthesizing an aromatic amine derivative of (R)-2-amino-1-butanol as a chiral selector and binding to L-tyrosine-modified cyanogen bromide (CNBr)-activated Sepharose 4B and then, packed into the separation column. The chromatographic performance of the separation column was evaluated with racemic mandelic acid and 2-phenylpropionic acid by using phosphate buffers at three different pHs as mobile phase. In the resolution processes, the prepared solutions were loaded onto the separation column at two different concentrations and at three different pHs for each racemic organic acid, separately. Enantiomeric excess (ee%) of the eluates was determined on CHIRALPAK AD-H chiral analytical column by HPLC. The maximum ee% for mandelic acid and 2-phenylpropionic acid was determined to be 60.84 and 27.4, respectively. Separation factors (k1 ’ , k2 ’ , α, and Rs) were calculated for each acid. The structures of the obtained compounds were characterized using the spectroscopic methods (NMR, and elemental analysis). In the second part of the study; enantioselective interactions between the prepared CSP and the analytes have been widely studied by docking, molecular dynamics simulation and quantum mechanical computation methods. The reason of column eluation of rac-2-phenylpropionic acid with lower enantiomeric yield was explained by these techniques.Öğe Electronic properties of Cu/n-InP metal-semiconductor structures with cytosine biopolymer(Polska Akademia Nauk, 2015-09) Güllü, Ömer; Türüt, AbdülmecitThis work shows that cytosine biomolecules can control the electrical characteristics of conventional Cu/n-InP metal-semiconductor contacts. A new Cu/n-InP Schottky junction with cytosine interlayer has been formed by using a drop cast process. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Cu/cytosine/n-InP structure were investigated at room temperature. A potential barrier height as high as 0.68 eV has been achieved for Cu/cytosine/n-InP Schottky diodes, which have good I-V characteristics. This good performance is attributed to the effect of interfacial biofilm between Cu and n-InP. By using C-V measurement of the Cu/cytosine/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as a function of frequency. Also, the interface-state density of the Cu/cytosine/n-InP diode was found to vary from 2:24 × 1013 eV-1cm-2 to 5.56× 1012 eV-1 cm-2.Öğe On solving partial differential eqauations of fractional order by using the variational iteration method and multivariate padé approximation(European Journal of Pure and Applied Mathematics, 2013-04) Turut, Veyis; Güzel, NuranIn this article, multivariate Padé approximation and variational iteration method proposed by He is adopted for solving linear and nonlinear fractional partial differential equations. The fractional derivatives are described in the Caputo sense. Numerical illustrations that include nonlinear timefractional hyperbolic equation and linear fractional Klein-Gordon equation are investigated to show efficiency of multivariate Padé approximation. Comparison of the results obtained by the variational iteration method with those obtained by multivariate Padé approximation reveals that the present methods are very effective and convenient.Öğe Multivariate padé approximation for solving nonlinear partial differential equations of fractional order(Hindawi, 2013-03-16) Turut, Veyis; Güzel, NuranTwo tecHniques were implemented, the Adomian decomposition method (ADM) and multivariate Pade approximation (MPA), for ´ solving nonlinear partial differential equations of fractional order. The fractional derivatives are described in Caputo sense. First, the fractional differential equation has been solved and converted to power series by Adomian decomposition method (ADM), then power series solution of fractional differential equation was put into multivariate Pade series. Finally, numerical results were ´ compared and presented in tables and figures
