Makale 2010-2019 yılları

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Browsing Makale 2010-2019 yılları by Publisher "Elsevier"

Now showing 1 - 6 of 6
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    An EPR study of clinoptilolite from Bigadiç in Turkey
    (Elsevier, 2016-01) Bıyık, Recep; Tapramaz, Recep; 0000-0001-7929-4395; TAEK-ÇNAEM
    Natural and synthetic zeolites are industrial materials. They are used in many applications as food additives, molecular sieve to trap unwanted ingredients, as heavy metallic ions and groups, as shielding against radiations etc. EPR spectroscopy is a tool to characterize paramagnetic centers and radicals in the zeolite and clay type minerals. In this study natural cliptonilolite obtained from a mine in Bigadiç in western Anatolia, Turkey, was studied using electron paramagnetic resonance spectroscopy (EPR) at room temperature in natural form,following treatment of the samples: adsorbing of CO2, H2S, and SO2 gases, [Cu(H2O)6]2 ions and exposure to gamma rays. Mn atoms become paramagnetic Mn2+ ions when CO2 and H2S gases are adsorbed to clinoptilolite and when SO2 gas is adsorbed the system becomes unstable and the structure of the paramagnetic center changes with time. When Cu2+ ions are adsorbed to the Bigadiç clinoptilolite, the values of the EPR parameters are consistent with the distorted octahedral symmetry environment and after the exposure to gamma rays from a Co-60 source gives O23- radical.
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    Application of CNUREAS and MCNP5 codes to VVER-1000 MOX core computational Benchmark
    (Elsevier, 2015) Şentürk Lüle, Senem; Özdemir, Levent; Erdoğan, Adem; TAEK-ÇNAEM
    In order to strengthen the nuclear design calculation capacity in Turkey, CNUREAS (Cekmece Nuclear Reactor System) was developed to provide easy usage of neutronic and thermal hydraulic nuclear codes included in the CNUREAS package. It was tested and used for research reactors and PWR type power reactors. Modifications were performed to add hexagonal geometry support taking into account VVER type reactors employing hexagonal fuel assemblies that will be built in Turkey. “VVER-1000 MOX Core Computational Benchmark” was used to test new features of the CNUREAS. The maximum deviation in effective multiplication factor results of CNUREAS was 0.7% with deterministic codes and 1.5% with Monte Carlo codes. It was concluded that CNUREAS can be used for neutronic calculations of VVER type power reactors with appropriate cross section libraries and deterministic and Monte Carlo techniques give comparable results when both provided with appropriate cross section libraries.
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    Effect of particle size on TL dosimetric properties of household salt
    (Elsevier, 2017-07) Yüce, Ülkü Rabia; Engin, Birol; TAEK-SANAEM
    This work investigates the effect of particle size in the thermoluminescence (TL) response of household salt that classified into five size fractions between 63 and 250 µm. Irradiation induced two TL peaks at 110°C and 240°C for each particle size fraction. Besides these peaks, two additional glow peaks were also observed at 80°C and 300°C for small particle size fractions < 90µm. The complexity of the glow curve pattern increased with decreasing particle size (<125 µm). The intensity of the dosimetric TL peak at 240°C increases with increasing particle size. The maximum beta radiation sensitivity of salt samples was obtained for the particle sizes of 125-180 µm and 180-250 µm. For different particle sizes, the stability of dosimetric TL peak at room temperature was studied over a storage period of 30 days.The kinetic parameters of dosimetric TL peak were determined at different particle sizes using the initial rise (IR), peak shape (PS) and variable heating rate (VHR) methods and the results are discussed in detail. Moreover, the variations of the glow peaks depending on the heating rate were also studied.
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    Investigation of gamma irradiation and storage period effects on the nutritional and sensory quality of chickpeas, kidney beans and green lentils
    (Elsevier, 2017) Aylangan, Ayça; Özyardımcı, Berna; İç, Erhan; TAEK-SANAEM
    The objectives of this study were to determine the effects of gamma irradiation and storage period on the content of the total carotenoids, the oligosaccharides raffinose and stachyose, and the vitamins thiamine (B1) and riboflavin (B2) in pulses. Chickpea, kidney bean and green lentil samples were subjected to gamma irradiation doses of 0.25, 0.50 and 1.0 kGy followed by storage at room temperature for 12 months. The total carotenoids content was measured by spectrophotometer. Raffinose and stachyose were determined by high-performance liquid chromatography (HPLC) with refraction index detection and thiamine and riboflavin concentrations by HPLC with fluorescence detection. The impact of the irradiation dose can be seen in the result of the total carotene tests for lentils. The three different irradiation doses applied did not have significant effects on the levels of riboflavin and thiamine. The effect of the storage period was found to be significant on the raffinose and stachyose content but there were no significant changes following the applied irradiation doses. In the sensory evaluation the testers were not be able to differentiate between the 0.25, 0.50 and 1 kGy applied irradiation doses and the unirradiated samples. The results of these studies suggest that irradiation with 1.0 kGy gamma rays cause tolerable losses in the nutrients studied in chickpeas, kidney beans and green lentils.
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    Measurement of enhanced radium isotopes in oil production wastes in Turkey
    (Elsevier, 2015-03) Parmaksız, Aydın; Ağuş, Yusuf; Bulgurlu, Figen; Bulur, Emine; Öncü, Tolga; Özkök, Yücel Özer; AAH-5187-2020; /0000-0003-4000-5175; TAEK-SANAEM
    Gamma dose rates of oil production equipment and wastes were measured externally by survey meter. They were found to be between 0.2 μSv h−1 and 25.7 μSv h−1. Activity concentrations of radium isotopes in crude oil, scale, sludge, contaminated soil and water samples were determined by gamma spectrometric method. Activity concentrations of 224Ra, 226Ra and 228Ra in samples varied from MDA to 132,000 Bq kg−1. Radium isotopes enriched up to 14,667 times in scale samples. The highest value of 226Ra was found to be 35,122 ± 1,983 Bq kg−1 for sludge samples. Activity concentrations of a considerable number of samples were found to be higher than the exemption level recommended by IAEA. Measurement results revealed that oil production wastes caused soil contamination up to 70,483 Bq kg−1. They may pose a radiological risk for workers and members of the public.
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    Synthesis, characterization, and evaluation of (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate as a biological agent and an anion sensor
    (Elsevier, 2016) Zeyrek, C. Tuğrul; Boyacıoğlu, Bahadır; Yıldız, Mustafa; Ünver, Hüseyin; Yolal, Devrim; Demir, Neslihan; Elmalı, Ayhan; Aslan, Kadir; 0000-0001-6744-7841; TAEK-ANAEM
    An amino acid derived and bidentate Schiff base, (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate (ligand), was synthesized from the reaction of glycine-methyl ester hydrochloride with 2-hydroxy-1-naphthaldehyde. Characterization of the ligand was carried out using theoretical quantum-mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV-Visible spectroscopy, which were in good agreement with the structure predicted by the theoretical calculations using density functional theory (DFT). Antimicrobial activity of the ligand was investigated for its minimum inhibitory concentration (MIC) to several bacteria and yeast cultures. UV-visible spectroscopy studies also shown that the ligand can bind calf thymus DNA (CT-DNA) electrostatic binding. In addition, DNA cleavage study showed that the ligand cleaved DNA without the need for external agents. Energetically most favorable docked structures were obtained from the rigid molecular docking of the compound with DNA. The compound binds at the active site of the DNA proteins by weak non-covalent interactions. The colorimetric response of the ligand in DMSO to the addition of equivalent amount of anions (F-, Br-, I-, CN-, SCN-, ClO4-, HSO4-, AcO-, H2PO4-, N3- and OH-) was investigated and the ligand was shown to be sensitive to CN- anion.