Browsing by Author "Akin, A"

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    Thermally stimulated luminescence glow curve structure of β-irradiated CaB4O7:Dy
    Akin, A; Ekdal, E; Arslanlar, YT; Ayvacikli, M; Karali, T; Can, N
    Thermally stimulated luminescence glow curves of CaB4O7:Dy samples after beta-irradiation showed glow peaks at similar to 335, 530 and 675 K, with a heating rate of 2 K/s. The main peak at 530 K was analyzed using the T-max-T-stop method and was found to be composed of at least five overlapping glow peaks. A curve-fitting program was used to perform computerized glow curve deconvolution (CGCD) analysis of the complex peak of the dosimetric material of interest. The kinetic parameters, namely activation energy (E) and frequency factor (s), associated with the main glow peak of CaB4O7:Dy at 520 K were evaluated using peak shape (PS) and isothermal luminescence decay (ILD) methods. In addition, the kinetics was determined to be first order (b = 1) by applying the additive dose method. The activation energies and frequency factors obtained using PS and ILD methods are calculated to be 0.72 and 0.72 eV and 8.76 x 10(5) and 1.44 x 106/s, respectively. Copyright (C) 2014 John Wiley & Sons, Ltd.
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    Determination of synthesis conditions of medium, high, and overbased alkali calcium sulfonate
    Besergil, B; Akin, A; Çelik, S
    This review covers a method for preparing an overbased detergent-dispersion additive called overbased calcium sulfonate solution (OBCSS) containing 38.9% (w/w) CaCO3, with a total base number (TBN) value of 436 mg KOH, starting from neutral calcium sulfonate solution (NCSS).(1,2) After the column conditions were optimized, the reaction parameters (P-CO2 and the amounts of Ca(OH)(2), water, and monoethanolamine (MEA)) were examined throughout the tests. The first product medium alkali calcium sulfonate solution (MACSS) with 8.5% (w/w) CaCO3 (TBN = 95 mg KOH/g) is obtained, but higher base values could not be reached. In the second stage, monoethanolamine is added to the feed as a promoter and high alkali calcium sulfonate solution (HACSS) containing 30.4% (w/w) CaCO3 with the value of TBN = 274 mg KOH/g is obtained. In the third stage of the study, targeted product OBCSS is obtained by using HACSS as a feedstock component instead of NCSS.