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Najafi R.,Islamic Azad University | Kucuk G.D.,Igdr University | Celik E.,Atatürk University
Mathematical Methods in the Applied Sciences | Year: 2017

This paper is devoted to the time-fractional gas dynamics equation with Caputo derivative. Fractional operators are very natural tools to model memory-dependent phenomena. Modified iteration method is proposed to obtain the approximate and analytical solution of the fractional gas dynamics equation. This method is a combined form of the new iteration method and Laplace transform. Modified iteration method really is powerful and simple method compared with other methods. Existence and uniqueness of solution are proven. Numerical results for different cases of the equation are obtained. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.


Palabiyik I.,Namik Kemal University | Toker O.S.,Yildiz Technical University | Karaman S.,Erciyes University | Yildiz O.,Igdr University
Journal of Cereal Science | Year: 2017

In this work, starch pasting curves were reinterpreted with suitable models to show deficiency of widely used starch pasting parameters in the literature. The aim was to attract scientific attentions to the behavior and dynamics of the curve with respect to process parameters instead of values on the curve. Mainly, pasting curve was separated into four parts combining sigmoidal gelatinization model, exponential thinning model and Arrhenius temperature model. For the gelatinization part, starch swelling rate, water binding capacity and starch resistivities to heat and shear might be compared by the proposed model parameters. Amylose and damaged starch contents of starches had a good relation with Arrhenius and exponential model parameters. Activation energy values gave clues about retrogradation rate of starches and changed between 7142 and 17,327 kJ/mol. © 2017 Elsevier Ltd


GA14lASin I.,Atatürk University | GA14lASin I.,King Saud University | Scozzafava A.,University of Florence | Supuran C.T.,University of Florence | And 6 more authors.
Journal of Enzyme Inhibition and Medicinal Chemistry | Year: 2016

Rosmarinic acid (RA) is a natural polyphenol contained in many aromatic plants with promising biological activities. Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread and intensively studied metalloenzymes present in higher vertebrates. Acetylcholinesterase (AChE, E.C. 3.1.1.7) is intimately associated with the normal neurotransmission by catalysing the hydrolysis of acetylcholine to acetate and choline and acts in combination with butyrylcholinesterase (BChE) to remove acetylcholine from the synaptic cleft. Lactoperoxidase (LPO) is an enzyme involved in fighting pathogenic microorganisms, whereas glutathione S-transferases (GSTs) are dimeric proteins present both in prokaryotic and in eukaryotic organisms and involved in cellular detoxification mechanisms. In the present study, the inhibition effects of rosmarinic acid on tumour-associated carbonic anhydrase IX and XII isoenzymes, AChE, BChE, LPO and GST enzymes were evaluated. Rosmarinic acid inhibited these enzymes with Kis in the range between micromolar to picomolar. The best inhibitory effect of rosmarinic acid was observed against both AChE and BChE. © 2016 Informa UK Limited, trading as Taylor & Francis Group.


Gulcin I.,Atatürk University | Gulcin I.,King Saud University | Scozzafava A.,University of Florence | Supuran C.T.,University of Florence | And 4 more authors.
Journal of Enzyme Inhibition and Medicinal Chemistry | Year: 2016

Caffeic acid phenethyl ester (CAPE) is an active component of honeybee propolis extracts. Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread and intensively studied metalloenzymes present in higher vertebrates including humans as many diverse isoforms. Acetylcholinesterase (AChE) is responsible for acetyl choline (ACh) hydrolysis and plays a fundamental role in nerve impulse transmission by terminating the action of the ACh neurotransmitter at cholinergic synapses and neuromuscular junctions. Butyrylcholinesterase (BChE) is another enzyme abundantly present in the liver and released into blood in a soluble form. Lactoperoxidase (LPO) is an enzyme involved in fighting pathogenic microorganisms whereas glutathione S-transferases (GSTs) are dimeric proteins present both in prokaryotic and eukaryotic organisms and involved in cellular detoxification mechanisms. In the present study, the inhibition effect of CAPE on human carbonic anhydrase (hCA) isoforms I, II, IX, and XII, AChE, BChE, LPO, and GST was evaluated. CAPE inhibited these enzymes with Ki s in the range between micromolar to picomolar. The best inhibitory effect was observed against AChE and BChE. © 2015 Informa UK Limited, trading as Taylor & Francis Group.


Topkaya R.,Igdr University
Journal of Superconductivity and Novel Magnetism | Year: 2017

Fe/Cu/Fe multilayer thin film was grown on Si (100) substrate by using magnetron sputtering technique at room temperature. Dynamic and static magnetisations of the film have been investigated using ferromagnetic resonance (FMR) and vibrating sample magnetometer (VSM) techniques in the temperature range of 10–300 K. From the room-temperature in-plane FMR measurements, a growth-induced uniaxial magnetic anisotropy was observed. Out-of-plane FMR measurements exhibited a large magnetic anisotropy due to a large saturation magnetisation of Fe. A computer code was written to simulate the experimental FMR data and to obtain the magnetic parameters of the Fe/Cu/Fe multilayer thin film. g value, effective magnetisation, uniaxial anisotropy field and perpendicular anisotropy constant from the fitting of the angular dependence of the resonance field at both the in-plane and out-of plane geometries were determined. The exchange bias effect was observed from the low-temperature VSM measurements. The saturation magnetisation and coercive field decrease with increasing temperature due to the increase of the thermal fluctuations. © 2016, Springer Science+Business Media New York.


Meristem derived in vitro plantlets of potato (Solanum tuberosum L.) cultivars Pasinler, Granola, and Caspar were micropropagated on agar-solidified MS medium containing different concentrations of jasmonic acid (JA) using single-node stem cuttings. The results of the study showed that inclusion of 1.0 µM JA in the MS medium provided a substantial and visible increase in most of the plantlet characteristics studied and the effect of this concentration was more pronounced compared to the control and all other JA concentrations. The highest number of shoots (8.00), nodes (19.00), leaves (19.00), and roots (15.75) on cv. Caspar and a maximum shoot length (15.13 cm) was observed on cv. Granola from 1.0 µM JA concentration. This concentration of JA also helped to induce longest roots (14.95 cm) on cv. Pasinler. The highest plantlet fresh weight from cv. Pasinler (649.38 mg), and cv. Caspar (630.18 mg), and maximum dry weight of plantlets from cv. Pasinler (98.58 mg), cv. Caspar (93.89 mg) and cv. Granola (79.03 mg) were noted on MS medium containing 1.0 µM of JA. Since the application of JA accelerates the multiplication of young plantlets throughout the year without depending on the season, this allows fast commercial propagation of new potato cultivars. These results may also serve as basis for the mass production of these economically important potato cultivars through in vitro micropropagation techniques and microtuberization studies. © 2016, Centenary University. All rights reserved.


Topkaya R.,Igdr University
Journal of Superconductivity and Novel Magnetism | Year: 2017

CoTa alloy thin films were prepared by using magnetron sputtering technique on Si substrates at room temperature. The effect of post-annealing on structural and magnetic properties of CoTa alloy thin films has been investigated in the temperature range of 10–300 K using X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) and vibrating sample magnetometer (VSM) techniques. It has been observed that the structural and magnetic properties of the prepared films depend on post-annealing. From XRR measurements, the thicknesses of the samples were determined. SEM images indicate the formation of the clusters on the surfaces of CoTa alloy thin film with the post-annealing. The cobalt core peaks indicate the existence of metallic cobalt in the samples. EPR spectra with paramagnetic behaviour appear for both as-grown and annealed CoTa alloy thin films. EPR and VSM measurements have indicated that after the post-annealing, paramagnetic behaviour weakens, ferromagnetic behaviour enhances and effective magnetic anisotropy forms. © 2017 Springer Science+Business Media New York


Topkaya R.,Igdr University
Applied Physics A: Materials Science and Processing | Year: 2017

Bi–La-substituted M-type barium hexaferrites, BaBixLaxFe(12-2x)O19 (0.0 ≤ x ≤ 0.2), were prepared by the standard solid-state reaction method. The effect of temperature and concentration on the structural and magnetic properties of BaBixLaxFe(12-2x)O19 hexaferrite powders has been comprehensively investigated. XRD analysis confirms the formation of M-type hexagonal crystal structure with P63/mmc space group. The average crystallite size of the powders was determined using Scherrer’s formula (in the range of 66–77 nm.). Lattice parameters were found to increase with the increase in Bi–La substitution. Magnetic properties were enhanced by substitution. Magnetic hysteresis loops were analysed using a ‘Law of Approach to Saturation’ method. It was obtained the saturation magnetization value close to the bulk value. Bi–La substitution gives rise to increase of saturation magnetization, coercive field, and effective magnetic anisotropy constant for both 10 and 300 K. It is observed from FMR measurements that resonance field increases with the concentration. The broad FMR linewidth of almost 2.5 kOe indicates the existence of the particles with randomly distributed anisotropy axis. The enhanced magnetic properties make these powders a good candidate for potential applications in permanent magnets at low cost and microwave absorption devices. © 2017, Springer-Verlag GmbH Germany.


Topkaya R.,Igdr University
Journal of Alloys and Compounds | Year: 2017

Zinc doped barium hexaferrite powders with chemical composition BaFe12-xZnxO19 (0.0 ≤ x ≤ 0.3) were synthesized by sol-gel auto combustion method. The effect of zinc ion concentration on the temperature-dependent magnetic properties of BaFe12-xZnxO19 hexaferrites has been comprehensively investigated in the temperature range of 10–300 K and magnetic field of ±50 kOe. XRD powder patterns showed a pure single phase structure. The Rietveld refinement of the XRD patterns revealed the existence of hexagonal structure with P63/mmc space group. The average crystallite size of the powders was found to be in the range of 46–51 nm. The ratio of lattice constants (c/a) lower than 3.98 proves that BaFe12-xZnxO19 hexaferrite powders have a M-type hexagonal ferrite structure. The nonmagnetic zinc ions strongly affect the magnetic properties of the powders. The magnetic hysteresis loops were fitted by using a ‘law of approach to saturation’. From the linear fitting, the magnetic parameters were calculated such as saturation magnetization, effective magnetic anisotropy and anisotropy field. The saturation magnetization values close to bulk values were determined as 66.67 and 95.47 emu/g for 300 and 10 K, respectively, which makes the samples a promising candidate for electronic applications. The saturation magnetization slowly decreases and then increases, whereas the coercive field continuously decreases with the increasing of Zn2+ concentration (x). The squareness ratio (Mr/Ms) of about 0.5 confirmed that the hexaferrite powders have a uniaxial anisotropy. The effective magnetic anisotropy constant (Keff) was observed to decrease with the increase in Zn2+concentration. When the temperature increases, the saturation magnetization continuously decreases because of the weakening of superexchange interaction and the coercive field increases due to the increasing of anisotropy field. FMR measurements confirmed the ferromagnetic behaviour of the substituted barium hexaferrite powders. The high resonance field values of the powders (a maximum resonance field of 16 kOe) originate from the hard magnetic property of the hexaferrites used in this study. The absorption curves have a broad FMR linewidth due to an anisotropy axis randomly distributed and the competing between anisotropy and exchange fields. © 2017 Elsevier B.V.


The main aim of this study was to model avocado production in Turkey for 2016-2025 period using 1988-2015 years FAOSTAT data. Avocado production time series data for the 1988-2015 period was found non-stationary. Stationarity was obtained after taking the first difference of the time series. Three Exponential Smoothing (Holt, Brown and Damped) methods were compared to model avocado production. Brown exponential smoothing model was the most appropriate forecasting model for avocado production. We forecasted that the avocado production in Turkey will show increase from 2004 tons to 3156 tons for the 2016-2025 period. The results of this study could help policy makers to develop macro-level policies for food safety and more powerful strategies for better planning avocado production in Turkey for the future. © 2017, Centenary University. All rights reserved.

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