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    Calcium-based TLD materials for radiation applications
    (Pergamon-Elsevier Science Ltd, 2021) Yilmaz, Demet; Büyükyıldız, Mehmet
    This study focused on radiation interaction parameters of four compounds of calcium which are the most common types of thermoluminescence dosimetry (TLD). Firstly, the mass attenuation coefficients (MAC, mu/rho) and effective atomic numbers (Z(eff)) of calcium based-TLD materials such as CaSO4, CaF2, Ca5F(PO4)(3) and CaCO3 were measured in the energy region 121.87-1408.01 keV. The values of MACs and Z(eff)s of CaSO4, CaF2, Ca5F (PO4)(3) and CaCO3 were then theoretically calculated at same photon energies. Good agreements were observed between the experimental and theoretical results for MAC and Z(eff) values (diff. <= 8.17%). In addition, the mass energy absorption coefficients, Kerma relative to soft tissues, equivalent atomic number (Z(eq)), and buildup factors (energy absorption and exposure buildup factors; EABF, EBF) were theoretically calculated in the energy region 0.08-2 MeV. The results displayed significant changes in equivalent atomic number, such that these values increased with the increasing energy and after 1 MeV it generally decreased. CaCO3 was finally found the best tissue equivalent material because of fact that the values of Kerma and Z(eff) ratios were nearest to unity (1) among calcium-based TLD materials at the studied energies.
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    Closed-loop Mechanical Recycling Opportunities in Industrial Cotton Wastes
    (Taylor & Francis Inc, 2022) Yurtaslan, Ozge; Kurtoglu, Sule Altun; Yilmaz, Demet
    Reusing industrial wastes in textile production is essential to reduce the total environmental burden of textile products. This study proved that the wastes generated in the ring-spinning process of a lightweight cotton shirting-producing company could be turned into fabrics used in shirts, jackets, and trousers. A total of 21 different yarns in four different counts containing 5-100% waste were produced in OE-rotor and ring spinning lines. These yarns were used to produce 12 different fabrics. Some of the produced yarns and fabrics met the criteria required for the lightweight fabrics. Others, specifically yarns and fabrics produced from short fiber wastes, exhibited suitable properties for the medium and coarse yarn count segment. According to the gate-to-gate LCA analysis, virgin cotton yarn and 100% cotton waste-contained yarn had similar environmental impacts in terms of OE-rotor spinning process.