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    Assessment of radioactivity from groundwater samples from selected areas of Western Black Sea Region, Turkey
    (Walter De Gruyter Gmbh, 2020) Oge, Tuba Ozdemir; Ozdemir, Firdevs Banu
    In this study, radon concentration measurements and chemical analyses of groundwater samples were performed in four sampling locations of Bartin Province of Western Black Sea Region, Turkey. Rn-222 analysis was carried out in groundwater samples with liquid scintillation counting system in accordance with ASTM D5072 standard. The pH, total hardness, alkalinity and dissolved oxygen parameters of the groundwater samples were also determined. The radon concentrations for the water samples ranged between <3.00 Bq/L-12.03 Bq/L. Thirty eight percentage of the samples slightly exceeded the permissible limit of 11.1 Bq/L specified by USEPA for drinking waters. The annual effective doses of groundwater samples were calculated in the range of 7.41-30.74 mu Sv/y for ingestion of water (E-w.Ig), and in the range of 7.31-30.31 mu Sv/y for inhalation of radon released from water (E-w.Ih). The total calculated annual effective doses due to ingestion and inhalation were found to be below the limit value of 100 mu Sv/y specified by the World Health Organization (WHO). The radioactivity measurement results significantly varied for three sampling points but not for one sampling point on two different measurement dates, which is attributed to the differences in geological structure. The chemical analysis results, except for total hardness in two sampling points, were within the permissible limits specified by international standards.
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    Indoor and tap water radon (222Rn) concentration measurements at Giresun University campus areas
    (Pergamon-Elsevier Science Ltd, 2018) Buyukuslu, Halim; Ozdemir, F. Banu; Oge, Tuba Ozdemir; Gokce, Halil
    In this study, indoor (air) and tap water Radon (Rn-222) measurements were performed at various campus areas of Giresun University. The measurement and analysis results were compared with the values recommended by international and national organizations and those reported in literature studies. The measured and calculated values were found to be under the recommended limits. Also, annual effective dose values were evaluated to determine the annual radon exposure of an individual working in the measurement area. Indoor radon concentration values measured by CR-39 detectors were in the range of 76 Bq/m(3)-504 Bq/m(3) and the mean concentration value was obtained as 193.7 Bq/m(3). The radon concentrations in tap water samples were found to be in the range of 0.98 Bq/L-27.28 Bq/L. The annual mean effective doses (E-wig) of drinking water samples were calculated in the range of 9.9-150.4 (mu Sv/y) for ingestion and 0.97-14.84 (mu Sv/y) for inhalation calculations. Excess life time cancer risk (ELCR) was estimated as 0.54%. Radon dose rate in terms of mean annual working level month was calculated as 0.246 WLM/year. The study was performed with a view to contribute to further studies in the related field and constitute a basis for the measurements conducted in this area.
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    Investigation of tribological properties of polypropylene (PP)- Acrylonitrile butadiene styrene (ABS) blends reinforced with graphene nano-platelets (GNPs)
    (Elsevier Sci Ltd, 2023) Karteri, Ibrahim; Oge, Mecit; Kucuk, Yilmaz; Oge, Tuba Ozdemir; Ozdemir, Firdevs Banu; Karatasli, Muhammet; Culha, Mehmet Ali
    The tribological response of PP-ABS/GNPs nanocomposites fabricated via extrusion and injection molding with varying wt% GNPs fractions were examined under varying normal load and sliding speed wear test parameters. The specimens with 3% GNPs and 11% GNPs respectively exhibited the lowest and highest specific wear rates and COF under all test conditions. Increased load led to significantly reduced COF values, whereas increased sliding speed led to a slight reduction in COF by contributing to the formation of a continuous transfer layer. Addition of GNPs helped to retain the worn material on the contact surface and led to improved wear resistance up to the weight fraction of 3% after which non-homogeneous dispersion of GNPs occurred.