Browsing by Author "Aydin, Fatih"

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A Novel Numerical Approach for the Third Order Emden-Fowler Type Equations
(Wiley-v C H verlag Gmbh, 2024) Sakar, Mehmet Giyas; Saldir, Onur; Aydin, Fatih; Rece, M. Yasin
This article aims to achieve robust numerical results by applying the Chebyshev reproducing kernel method without homogenizing the initial-boundary conditions of the Emden-Fowler (E-F) equation, thereby introducing a new perspective to the literature. A novel numerical approach is presented for solving the initial-boundary value problem of third-order E-F equations using Chebyshev reproducing kernel theory. Unlike previous applications, which were confined to homogeneous initial-boundary value problems or required homogenization, the proposed method is effective for both homogeneous and nonhomogeneous cases. To handle the initial-boundary conditions of the E-F equations, additional basis functions are introduced rather than imposing conditions on the reproducing kernel Hilbert space. The method's effectiveness is demonstrated through five examples, which validate the theoretical analysis. Overall, the results emphasize the method's efficiency.
Purification and Characterization of Angiotensin-Converting Enzyme (Ace) From Sheep Lung
(Springer, 2021) Aydin, Fatih; Turkoglu, Vedat; Bas, Zehra
Angiotensin-converting enzyme (ACE, EC 3.4.15.1) in the renin-angiotensin system regulates blood pressure by catalyzing angiotensin I to the vasoconstrictor angiotensin II. In this study, the ACE was purified and characterized from sheep lung. The kinetic properties of the ACE were designated. The inhibition effect of captopril, a specific ACE inhibitor, was determined. ACE was purified from sheep lung using the affinity chromatography method in one step. NHS-activated Sepharose 4 Fast Flow as column filler and lisinopril as a ligand in this method used. The molecular weight and purity of ACE were designated using the SDS-PAGE method. Optimum temperature and optimum pH were found for purified ACE. K-M and V-max values from Lineweaver-Burk charts determined. The inhibition type, IC50, and K-i values of captopril on purified ACE were identified. ACE was 6405-fold purified from sheep lung by affinity chromatography in one step and specific activity was 16871 EU/mg protein. The purity and molecular weight of ACE were found with SDS-PAGE and observed two bands at around 60 kDa and 70 kDa on the gel. Optimum temperature and optimum pH were designated for purified ACE. Optimum temperature and pH were found as 40 degrees C and pH 7.4, respectively. V-max and K-M values were calculated to be 35.59 (mu mol/min).mL(-1) and 0.18 mM, respectively. IC50 value of captopril was found as 0.51 nM. The inhibition type of captopril was determined as non-competitive from the Lineweaver-Burk graph and the K-i value was 0.39 nM. As a result, it was observed in this study that the ACE enzyme can be successfully purified from sheep lungs in one step. Also, it was determined that captopril, which is a specific ACE inhibitor, has a significant inhibitory effect with a very low IC50 value of 0.51 nM.
Wear Resistance and Tribological Properties of Gnps and Mwcnt Reinforced Alsi18cunimg Alloys Produced by Stir Casting
(Elsevier Sci Ltd, 2021) Turan, Muhammet Emre; Aydin, Fatih; Sun, Yavuz; Zengin, Huseyin; Akinay, Yuksel
The present work aims to produce Multiwalled Carbon Nanotube (MWCNT) and Graphene Nanoplatelets (GNPs) reinforced AlSiCuNiMg alloy matrix composites via stir casting. The wear resistance and tribological performances of produced materials are examined by steel balls in dry sliding conditions under loads of 10 N, 20 N, and 40 N. The composites were produced by the combination of semi powder metallurgy and stir casting techniques and then a solid-solution + aging process was applied. The microstructures and phase-type of all specimens were examined by Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). The results of this study show that the wear rates of the matrix decreased significantly with the addition of GNPs and MWCNTs reinforcements. When sliding speed increased, wear rates for all produced samples decrease. Graphene reinforced composite exhibited the best tribological behavior among the prepared samples. The design of test conditions and the analysis of output responses were studied by statistical analysis of Taguchi array, analysis of variance (ANOVA) and regression models. ANOVA indicated that the wear rate was mainly affected by material content followed by sliding speed and applied load. The wear mechanisms were identified by characterizations of worn surface, wear debris and counterface material.