Volume 106, Issue 5

Activation cross-section of photon-induced reaction on structural materials 58 Ni and 59 Co was measured at the bremsstrahlung endpoint energy 15 MeV from an S band electron linac. The uncertainties in the (γ,n) reaction cross-section of both 58 Ni and 59 Co were estimated by using the concept of covariance analysis. The cross-section of 58 Ni(γ,n) 57 Ni reaction in the present work is slightly lower than the previous experimental data and the TENDL-2015 data. The cross-section of 59 Co(γ,n) 58 Co reaction has been measured for the first time. However, the present experimental data of 59 Co(γ,n) 58 Co reaction is very low in comparison to the TENDL-2015 and JENDL/PD-2004 data.

Solvent extraction of U(VI), Th(IV), Am(III) and lanthanides(III) from aqueous nitric acid solutions with 1,2,3-triazole–modified carbamoylmethylphosphine oxide (L) and [C 4 mim][Tf 2 N] ionic liquid dissolved in 1,2-dichloroethane was studied. A considerable synergistic effect in this system was observed. This effect is associated with the high hydrophobicity of the IL anions which participate in the formation of metal extracted ion species. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. The synergistic effect for metal ion extraction from aqueous nitric acid solutions with compound L and [C 4 mim][Tf 2 N] in 1,2-dichloroethane becomes weaker when the acidity of the aqueous phase increases. The partition of Tf 2 N − anions between the organic and aqueous phases is the major factor governing the extractability of metal ions in the L – IL synergistic system. The interaction of L with HTf 2 N and HNO 3 also substantially affects the efficiency of metal ion extraction.

An unexplored novel monoamide N,N′-bis(2-ethyl hexyl) α-hydroxy acetamide (BEHGA) was used as a carrier for transport of Am(III), Eu(III), Pu(IV/VI) and U(VI) from HNO 3 medium across a supported liquid membrane (SLM). Various parameters were investigated to obtain the optimum transport conditions. Transport rates followed the trend Pu(IV)>Am(III)≥Eu(III)>U(VI)> Pu(VI). The effects of macro concentrations of U(VI) and Nd(III) on the transport rate of Am(III) were studied. The diffusion coefficient value for the Am(III)-BEHGA system in HNO 3 medium was found to be ~1.8×10 −6 cm 2 /s. The standard deviation of the results obtained from transport experiments by this extractant was found to be ±5%. The membrane was found to be highly selective for actinides and lanthanides with respect to different fission products.

The adsorption of thorium(IV) was studied using a pseudo-polyrotaxane, which was obtained by the reaction of poly(propyleneglycol) (PPG) and 6-OTs- β -CD. The adsorption of thorium(IV) was examined as a function of the contact time, pH of the solution, adsorbent dose, concentration of thorium(IV) and temperature using batch adsorption experiments. The experimental results suggested that the optimum conditions were found to be at pH 3.5, contact time 40 min, 10 mg adsorbent doses, 20 mg L −1 thorium(IV) concentration and 298 K. The maximum adsorption capacity was found to be 15.366 mg g −1 . The thermodynamic parameters (Δ G 0 <0, Δ H 0 <0) were calculated, the result showed that the adsorption of thorium(IV) was exothermic and spontaneous process.

A nanoparticles chelating solution was synthesized by copolymerization of acrylonitrile (AN) and methacrylic acid (MAA) by radiation induced polymerization technique using 17 kGy irradiation doses. A high copolymer yield was obtained by using 80/20% of AN/MAA and comonomer concentration of 50% (w/w) at a dose rate of 2.58 KGy/h. The resultant cyano group (–CN) of nano-poly(AN/MAA) was converted by chemical modification using hydroxylamine (NH2–OH) to an amidoxime group [–C(=NOH)NH2], which was then confirmed by Fourier transform infrared spectroscopy (FTIR). The physico-chemical properties of poly(AN/MAA) and amidoximated poly(AN/MAA) nanoparticles were studied by FTIR, transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermal gravimetric analysis (TGA). The morphological analysis by TEM and DLS showed a spherical and uniform size of the amidoximated poly(AN/MAA) nanoparticles. TGA results indicated that the thermal stability of poly(AN/MAA) increased by the amidoximation process. The surface decontamination due to uranium was also investigated by the prepared chelating nanoparticles solution. A high purity germanium detector (HPGe) was used as a surface contamination detection tool. The results showed the presence of peaks at different energies, namely, 186.2 keV for Ra-226 (U-238) and 143.76 keV, 163.35 keV and 205.31 for U-235 before the decontamination process. The disappearance of these peaks after decontamination confirmed the applicability and efficiency of the nanoparticles solution in uranium surface decontamination.

This study aims to evaluate newly radioiodinated mesalamine (Mes) as a tracer for ulcerative colitis imaging. Mes was labeled with [ 125 I] with chloramine-T (Ch-T) as the oxidizing agent. Labeling factors such as pH, reaction temperature, reaction time, substrate amount and oxidizing agent amount were investigated to optimize the radiochemical yield (98.5%). The labeled compound was separated and purified using thin layer chromatography (TLC), paper electrophoreses and high performance liquid chromatography (HPLC). The biological distribution indicated that the radioiodinated mesalamine localization was highest (72.28%) in microbial model compared to normal mice (29.25%) at 120 min post injection. So, 125 I-Mes could be considered as a new radiotracer for ulcerative colitis.

The aim of this study is to determine the levels of background radiation in nine districts of Kırıkkale, Turkey. The outdoor gamma dose rate in the air was measured using a portable digital environmental radiation detector at 170 locations. The mean outdoor gamma dose rate in the air was determined as 121 nGy h −1 with a range between 23 and 320 nGy h −1 . The annual effective dose for districts was between 0.04 and 0.59 mSv year −1 with a mean value of 0.23 mSv year −1 . Excess lifetime cancer risk values for districts ranged from 0.14×10 −3 to 2.07×10 −3 with a mean of 0.80×10 −3 . The activity concentrations of 226 Ra, 232 Th, 40 K and 137 Cs in 84 soil samples were determined using HPGe detector. The mean activity values (ranges) of 226 Ra, 232 Th, 40 K and 137 Cs in soil samples were found to be 20.4 (4.9±3.0–53.0±0.8) Bq kg −1 , 38.8 (3.7±0.2–163.5±1.8) Bq kg −1 , 598.0 (108.5±70.2–1500.5±38.7) Bq kg −1 and 3.9 (0.2±0.1–11.9±0.7) Bq kg −1 , respectively. The mean activity concentration of 232 Th and 40 K was higher than the world’s mean value. The mean radium equivalent activity was 119.76 Bq kg −1 which is lower than the recommended maximum value of 370 Bq kg −1 . The mean external terrestrial gamma dose rate was found to be 56.71 nGy h −1 . This mean value was lower than the world mean of 60 nGy h −1 . The calculated external hazard value was 0.32 and within the acceptable limit which is less than unity (H ex ≤1). The indoor radon concentration in 150 houses for the summer and winter seasons was determined using solid state nuclear track detector (CR-39). The mean indoor concentration for the summer season was found to be 63.27 Bq m −3 ranging from 14.0±1.5 to 288.0±21.9 Bq m −3 . On the other hand, the mean indoor concentration in the winter season was found to be 86.94 Bq m −3 ranging from 17.0±4.5 to 484.0±26.9 Bq m −3 . The present results showed that the radon activity concentrations in winter were 42.3% higher than in the summer. The mean annual effective dose equivalent and lifetime cancer risk were also calculated.

Buildings materials contain natural primordial radionuclides of 40 K, 232 Th and 226 Ra ( 238 U). The research measures activity concentrations of 40 K, 232 Th and 226 Ra in different types of raw materials with different origins: volcanic, calcareous, zirconium minerals, silico-aluminous etc., used in Romanian building industry. This is important as these materials lead to an exposure of the public and workers from their ionizing radiations. Based on these activity concentrations an estimation of the radiological hazard is also made by analyzing radiological parameters such as radium equivalent activity ( Ra eq ), absorbed dose ( D ), annual effective dose equivalent ( AEDE ), external hazard index ( H ex ), internal hazard index ( H in ), gamma and alpha index and dose criterion. Important conclusions can be drawn from the analysis of these indexes in respect with the radiological hazard for the population health by using these materials. Most of materials measured in this work showed fairly low levels of radioactivity.

This manuscript reports the synthesis and characterization of caprylpyrazolone tailored silica nanospheres, synthesized through sol–gel procedure by activating the silica nanospheres with organosilane precursor and grafting with caprylpyrazolone. Its successful attachment to the silica is confirmed by FTIR, TGA and elemental techniques. The feasibility of the synthesized nanospheres as adsorbent was systematically checked by elimination of trace level of Cr(III) from aqueous medium, using radiotracer technique. A number of factors such as effect of pH, agitation time, adsorbent and adsorbate dosage were optimized to guarantee the use of the adsorbent for practical use. Various counter ions were added to the matrix solution to check the selectivity of the synthesized sorbent. Various rate equations and adsorption isotherms such as Freundlich, D-R and Langmuir were employed to suggest the mechanistic pathway of the adsorption process. The Cr(III) extraction was monitored at room and elevated temperatures and thermodynamic parameters such as change in enthalpy, entropy, and Gibbs free energy of the metal ion uptake were computed. The removal of Cr(III) is endothermic (∆ H =30.00 J mol −1 K −1 ) and spontaneous (∆ S =105.43 J mol −1 K −1 ) in nature. Application of the adsorbent to real water samples demonstrated the practical utility of the adsorbent. The sorbent displayed good stability. Its cleaning efficiency is not significantly affected after various adsorption-desorption cycles and so it can be used repeatedly.