Volume 108, Issue 5

Cross sections of a prospective medical radionuclide 117m Sn along with 113 Sn, 120m,122 Sb, 111,114m In and 118,119m,119g,121m,121g,123m Te generated in natural and enriched antimony targets by protons in a wide energy range up to 145 MeV were determined. A stacked-foil technique followed by gas chemical separation and γ-ray spectrometry were used. The obtained data were compared with experimental values reported in literature and with theoretical computations by ALICE, TALYS and Cascade-Evaporation-Fission codes. Production yields of 117m Sn and the main impurity 113 Sn were estimated for different irradiation modes.

Several 238 Pu-doped Eu monazite single crystals stored at ambient conditions are monitored for 15 years using Scanning and Transmission electron microscopy, spectroscopy, diffraction and optical microscopy. Despite preservation of high crystalline quality, mechanical cracking and formation of small flakes is observed. After several month of aging, a new phase appeared on surfaces of the crystals, which later formed a continuous shell of most crystallographic faces. Electron diffraction indicated that the shell consists of submicron Pu-containing rhabdophanes. Its formation likely occurs due to combined action of atmospheric moisture and recrystallisation of radiation damage in monazite domains adjacent to external and internal surfaces. Extent of the rhabdophane formation appears to be influenced by crystallography and Pu content of corresponding growth sectors of the parent monazite. Whereas macroscopic rhabdophanes and monazites are relatively stable against irradiation, formation of sub-microscopic particles is a point of concern for development of monazite-based ceramic forms for actinide immobilization.

The uranyl (UO 2 2+ )-aliphatic dicarboxylic acid complexes are studied by luminescence and UV-Vis spectroscopy in acetonitrile (MeCN) medium. The ligands used are malonic acid (MA), succinic acid (SA), glutaric acid (GA), adipic acid (AA) and pimelic acid (PA). The complexes of UO 2 2+ with the above ligands showed well resolved luminescence spectra at pH 4.0 with M/L = 5. Both luminescence and UV-Vis spectra indicated the formation of 1:2 and 1:3 complexes of UO 2 2+ with MA and GA, AA, PA, respectively. DFT computations indicated the formation of 1:2 chelate complex of UO 2 2+ with MA and two types of 1:3 complexes of UO 2 2+ with SA, GA, AA and PA. Furthermore, the effect of solvent (water and acetonitrile) on the UO 2 2+ -ligand complexes has been performed using COSMO model. The present study demonstrates, for the first time, the formation of tris complexes of uranyl with these ligands in acetonitrile medium.

Distribution of tritium between vapor and lithium chloride aqueous solutions at 30–80 °C has been studied with the aid of vacuum distillation technique. “Positive” H/T VPIE (separation ratio increases with solute concentration) was observed. This ratio depends linearly on the salt molality and decreases with temperature. The results are in agreement with theoretical estimates of “free” water – hydrate shell H/T isotope equilibrium constants done with DFT force field calculations and harmonic oscillator quantum statistics. Found growth of the separation ratio may be practically important for developing extractive distillation process to remove tritium from technological solutions and liquid wastes of nuclear industry.

The complexation of Eu(III) by hydro-soluble degradation products (HDPs) from a radio-oxidized polyesterurethane is investigated. The polyesterurethane Estane 5703 ® (PURe) is radio-oxidized at 1000 kGy with γ-rays at room temperature. The polymer is then hydrolysed by a simplified artificial cement pore water solution (pH 13.3) for 31 days at 60 °C. The HDPs within the leachate are characterized using gas chromatography-mass spectrometry, ionic chromatography, and TOC analyser. The complexation of Eu(III) is studied by time-resolved luminescence spectroscopy (TRLS). The main HDPs are adipic acid – hexane-1,6-dioic acid – and butane-1,4-diol. Unlike HDPs from non-irradiated PURe, the HDPs from 1000 kGy γ-irradiated PURe do form complexes with Eu(III) at pH 13.3. Neither adipate nor butane-1,4-diol are responsible for this complexation. The existence of several types of complexes is evidenced by TRLS and electrospray ionization mass spectroscopy (ESI-MS): complexation reactions and operational constants are proposed. The complexes formed at high pH (from 10 to 13) are different from the lower pH complexes. The lower pH complexes are studied by ESI-MS and two ligands are identified: adipate and an oligomer.

The imaging of organs is very important in the field of diagnosis especially in case of liver diseases. In the present work, carnosine was successfully labeled with iodine-131 at room temperature in acidic medium using chloramine-T (Ch-T) as moderate oxidizing agent. The parameters affecting labeling of carnosine such as amount of oxidizing agent, amount of substrate, pH value of the reaction mixture, reaction temperature and reaction time, were investigated. The best conditions for formation of 131 I-carnosine ( 131 I-CAR) complex were 40 μg of chloramine-T (Ch-T), 75 μg of carnosine, pH 4 and 45 min reaction time at room temperature. The radiochemical yield for 131 I-CAR complex was (91 ± 0.11) % at optimum conditions and the labeled complex was stable for 2 h after labeling process. Biodistribution study was achieved using three groups of rats (normal, treated by inactive carnosine and hepatotoxicity rats induced by CCl 4 ). Hepatotoxicity of liver was evaluated using different biochemical markers such as ALT, AST and ALK.P. The 131 I-CAR complex showed selective bio-localization in stomach and liver and its selectivity increases in acquired hepatotoxicity. The biological distribution indicates that the suitability of 131 I-CAR as a potential hepatotoxicity imaging to detect hepatitis and medical prognosis.

Technetium-99 is a long-lived fission product present in nuclear wastes, found mainly as Tc(VII) and Tc(IV) in the environment. The quantification of the equilibrium constants for the formation of Tc(IV) aqueous complexes has been limited to carboxylate ligands and interactions with the halides is mostly unknown. This work reports equilibrium constants of the formation of the TcO(OH) + complexes with Br − , in a 3 M NaClO 4 solution of pcH 2 and varied temperature, using a liquid-liquid extraction system. Neutron activation confirmed the suitability of the extraction technique for this work. Under the working conditions, Br − forms a weak exothermic TcO(OH)Br complex, with a Gibbs free energy (ΔG r ) of 3 ± 3 kJ · mol −1 at a temperature of 273.15 K. The values for ΔH r (−32 ± 3 kJ · mol −1 ) and ΔS r (106 ± 9 J · mol −1  · K −1 ) of the complexation reaction were quantified using a van’t Hoff analysis. This work also showed that bromide addition does not displace the hydroxide from TcO(OH) + , as the equilibrium constant of bromide addition is much weaker than the first hydrolysis constant of the metal.

L X-ray intensity ratios for CeO 2 , Sm 2 (SO 4 ) 3 , Ho 2 O 3 , and Yb 2 O 3 compounds were experimentally investigated. The measurements were gauged following excitation by 59.54 keV γ -rays from a 100 mCi 241 Am radioactive annular source at different temperatures in situ . Temperature change occurred between 50 °C and 400 °C. L X-ray emission spectra were obtained by using a solid-state Si(Li) X-ray detector. L X-ray production cross sections, intensity ratios, and full-width half maximum (FWHM) values for the compounds were determined by evaluating the emission spectra varying with the temperature. According to the results obtained, it was observed that L β 1 X-rays were less influenced in comparison with L α X-rays while L α X-rays were also less influenced in comparison with L β 2 X-rays.