Browsing by Author "Aktas B."

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    Magnetic anisotropy studies on FeNiCo/Ta/FeNiCo three layers film by layer sensitive ferromagnetic resonance technique
    (2004) Yildiz F.; Kazan S.; Aktas B.; Tarapov S.; Samofalov V.; Ravlik A.
    Two ferromagnetic layers that are separated by a non-magnetic spacer have been deposited in the presence of an external DC magnetic field that has been applied in a mutually perpendicular direction during the deposition of each layer. This thin three-layer film of FeNiCo/Ta/FeNiCo was then studied by electron spin resonance (ESR) technique for different directions of the external magnetic field with respect to the film plane. Beside very anisotropic and strong two main modes, relatively well-resolved and very weak subsidiary peaks in ESR spectra were observed on low field side of the main modes for almost every direction of the external field. The anisotropic behavior as the field is rotated from the film normal towards to the film plane is due to strong demagnetizing field. However, two fold (axial) small anisotropies having 90 degrees phase shifts with respect to the peaks from two different layers were seen to originate from field-induced anisotropy. The small peaks are attributed to magnetostatics modes as well. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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    Ferromagnetic resonance studies on (Co40Fe40B20)x (SiO2)1-x granular magnetic films
    (2006) Yildiz F.; Kazan S.; Aktas B.; Tarapov S.I.; Tagirov L.; Granovsky B.
    Magnetic properties of granular (Co40Fe40B20)x(SiO2)1-x thin films (x = 0.3 7 - 0.5 3) have been studied by ferromagnetic resonance (FMR) technique. Samples have been prepared by ion-beam deposition of Co-Fe-B particles and SiO2 on sitall ceramic substrate. The FMR measurements have been done for different orientations of DC magnetic field with respect to the sample plane. It was found that the deduced value of effective magnetization from FMR data of the thin granular film is reduced by the volume-filling factor of the bulk saturation magnetization. The overall magnetization changes from 152 to 515 G depending on the ratio of the magnetic nanoparticles in the SiO2 matrix. From angular measurements an induced in-plane uniaxial anisotropy has been obtained due to the preparation of the film conditions as well. © 2005 Elsevier B.V. All rights reserved.
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    The value of echocardiography versus cardiac troponin i levels in the early detection of anthracycline cardiotoxicity in childhood acute leukemia: Prospective evaluation of a 7-year-long clinical follow-up
    (2011) Oztarhan K.; Guler S.; Aktas B.; Arslan M.; Salcioglu Z.; Aydogan G.
    The present study was designed to evaluate the significance of echocardiography versus cardiac troponin I levels in early detection of anthracycline dependent cardiotoxicity in acute lymphoblastic leukemia (ALL) patients. A total of 276 pediatric ALL patients were included in the study prospectively along 3 phases of data collection lasted from 2002 to 2009; including phase I (March 2002 to February 2003; n = 25; 53.3% females), phase II (September 2003 to April 2004; n = 35; 57.1% females), and phase III (January 2005 to June 2009; n = 216; 52.7% females) with respect to cumulative anthracycline doses applied. Anthracycline was administered in accordance with berlin-Franfurt-Munich (BFM)-2000 protocol in doses of 30 to 350 mg/m (in the first phase) and 30 to 240 mg/m (in the following phases). Evaluation of cardiotoxicity was performed via echocardiography and measurement of cardiac troponin I levels. Patients in each phase were homogenous in terms of gender and age. Diastolic dysfunction determined via reduction E/A ratio below the cutoff value was demonstrated to deteriorate earlier than systolic functions and alteration in cardiac enzymes. Being similar between dose groups, cTnI levels were shown to rise in the presence of congestive heart failure. In conclusion, anthracycline cardiotoxicity appears to be detected in an earlier stage by using diastolic parameters compared to systolic parameters and cardiac enzymes. © 2011 Informa Healthcare USA, Inc.