Novel starch-tungsten (VI) oxide biocomposites: Preparation, characterization, and comparisons between experimental and theoretical photon attenuation coefficients.

This study synthesized biocomposites containing starch and WO3 at varying ratios of 10 %, 20 %, 30 %, 40 %, and 50 % and assessed their thermal and radiation-shielding properties. These biocomposites were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD) analysis, particle-size distribution assessments, scanning electron microscopy-energy dispersive X-ray spectroscopy, and thermogravimetric analysis-differential thermogravimetry measurements. Furthermore, the linear attenuation coefficients of the biocomposites were experimentally measured using an NaI(Tl) gamma spectrometry system and theoretically computed using XCOM and GAMOS simulations for comparisons. The XRD and particle-size distribution profiles of the WO3.2H2O powder, respectively, demonstrated evident diffraction peaks and favorable pore-size distributions. Morphological characterizations revealed that the WO3 particles were homogeneously dispersed throughout the starch matrix without any agglomeration. Comparisons of the thermal degradation rates revealed that the pure starch and starch +50%WO3 biocomposite began decomposing at approximately 200°Cand 300 °C, respectively, indicating that increasing WO3 proportions enhanced thermal stability. Furthermore, the starch +50%WO3 biocomposite demonstrated the highest experimental linear attenuation coefficient, with a value of 0.2510 ± 0.0848 cm-1 at a gamma energy of 662 keV. Meanwhile, XCOM and GAMOS simulations revealed theoretical attenuation coefficients of 0.1229 and 0.1213 cm-1 for pure starch and 0.2202 cm-1 and 0.2178 cm-1 for the starch +50%WO3 biocomposite at 662 keV, respectively.

Reference levels of natural radioactivity and (137)Cs in and around the surface soils of Kestanbol pluton in Ezine region of Çanakkale province, Turkey.

The aim of the study was to conduct a systematic investigation on the natural gamma emitting radionuclides ((226)Ra, (232)Th and (40)K) as well as (137)Cs in the surface soils from Kestanbol/Ezine plutonic area in Çanakkale province as part of the environmental monitoring program on radiologic impact of the granitoid areas in Western Anatolia. The activity measurements of the gamma emitters in the surface soil samples collected from 52 sites distributed all over the region has been carried out, by means of HPGe gamma-ray spectrometry system. The activity concentrations of the relevant radionuclides in the soil samples appeared in the ranges as follows: (226)Ra was 20-521 Bq kg(-1); (232)Th, 11-499 Bq kg(-1)and; (40)K, 126-3181 Bq kg(-1), yet the (137)Cs was much lower than 20 Bq kg(-1)at most. Furthermore, based on the available data, the radiation hazard parameters associated with the surveyed soils were calculated. The present data also allowed evaluation of some correlations that may exist in the investigated natural radionuclides of the soil samples from the plutonic area in Çanakkale province. It is concluded from the above that the concerned region did not lead to any significant radiological exposure to the environment.

A survey of natural radiation levels in soils and rocks from Aliaga-Foca region in Izmir, Turkey.

The gamma spectroscopic analysis of (226)Ra, (232)Th and (40)K has been carried out in surface soil samples collected from Aliaga-Foça industrial region. The rock samples as parent materials of the soils are also collected and analysed for relevant radionuclides in order to evaluate the natural radiation levels. In the present study, the mean activity concentrations and ranges of the related radionuclides in the soil samples from 60 sites distributed all over the region are as follows: (226)Ra is 38 (14-123) Bq kg(-1); (232)Th, 63 (27-132) Bq kg(-1) and (40)K, 633 (141-1666) Bq kg(-1). Meanwhile, the ranges of natural radionuclide activities in the rock samples characterising the region are 41-95 Bq kg(-1) for (226)Ra, 10-122 Bq kg(-1) for (232)Th and 264-1470 Bq kg(-1) for (40)K, respectively. Based on the available data, the radiation hazard parameters associated with the surveyed soils/rocks are calculated and the results do not exceed the permissible recommended values except for soils originated from Foça rhyolites and tuffs. Furthermore, the collected data allowed for the mapping of the measured activities and corresponding gamma dose rates.

The natural radioactivity contents in feed coals from the lignite-fired power plants in Western Anatolia, Turkey.

Lignite burning is one of the sources of technologically enhanced exposure to humans from natural radionuclides. In the preliminary study, part of the survey, the activity concentrations of (226)Ra, (232)Th and (40)K in 112 samples of feed lignites from seven lignite-fired power plants in Western Anatolia (Seyitömer, Tunçbilek, Orhaneli, Soma, Yatagan, Yeniköy and Kemerköy) were, therefore, determined by scintillation gamma spectrometry. The ranges of the relevant radionuclides in the lignite samples are as follows: (226)Ra, 23-291 Bq kg(-1); (232)Th, 12-68 Bq kg(-1); and (40)K, 67-284 Bq kg(-1). Taking the coefficient of variation (CV) as a measure of the variability, the CV is also calculated for the natural radionuclides in the feed lignites. Furthermore, the dose rates in the coal-handling areas due to external gamma radiation are found to be within the range specified by UNSCEAR (2000) report.

Natural radioactivity (226Ra, 232Th and 40K) and assessment of radiological hazards in the Kestanbol granitoid, Turkey.

The surveys of natural gamma-emitting radionuclides in rocks and soils from the Ezine plutonic area were conducted during 2007. Direct dose measurement using a survey meter was carried out simultaneously. The present study, which is part of the survey, analysed the activity concentrations of (238)U, (232)Th and (40)K in granitoid samples from all over the region by HPGe gamma spectrometry. The activity concentrations of (226)Ra ranged from 94 to 637 Bq kg(-1), those of (232)Th ranged from 120 to 601 Bq kg(-1)and those of (40)K ranged from 1074 to 1527 Bq kg(-1) in the analysed rock samples from different parts of the pluton. To evaluate the radiological hazard of the natural radioactivity in the samples, the absorbed dose rate (D), the annual effective dose rate, the radium equivalent activity (Ra(eq)) and the external (H(ex)) hazard index were calculated according to the UNSCEAR 2000 report. The thorium-to-uranium concentration ratios were also estimated.