Band 104, Heft 4

The activation cross sections of proton induced reactions on nat Sb target leading to the formation of the radioisotopes 121m,g,123m Te were measured. The experimental excitation functions were compared with the theoretical model calculations using the codes EMPIRE-3.1 and TALYS-1.4. The integral yields of the three radionuclides were calculated and the possibility of their production is discussed.

The extraction of Pu(IV) using 1.1 M solution of tri-iso-amyl phosphate (TiAP)/ n -dodecane (DD) from plutonium nitrate solutions in nitric acid media was examined as a function of equilibrium aqueous phase metal ion concentration and equilibrium aqueous phase acidity at 303 K. The nitric acid concentration in the organic phase was measured as a function of equilibrium organic phase plutonium concentration. The co-extraction of U(VI) and Pu(IV) was studied using 1.1 M TiAP/DD system as a function of their equilibrium aqueous phase metal ion concentration and compared with 1.1 M tri- n -butyl phosphate (TBP)/ n -DD system under identical conditions. Co-extraction and co-stripping of U(VI) and Pu(IV) were studied using 1.1 M TiAP/DD and 1.1 M TBP/DD systems in cross current mode to evaluate the number of stages required for the extraction and stripping of heavy metal ions (uranium and plutonium). The extraction and stripping efficiencies were calculated for both the systems. The saturation limit of the organic phase was also established in these studies.

The aim of the present study was to carry out uranium bioleaching via optimization of the leaching process using response surface methodology. For this purpose, the native Acidithiobacillus sp. was adapted to different pulp densities following optimization process carried out at a high pulp density. Response surface methodology based on Box-Behnken design was used to optimize the uranium bioleaching. The effects of six key parameters on the bioleaching efficiency were investigated. The process was modeled with mathematical equation, including not only first and second order terms, but also with probable interaction effects between each pair of factors.The results showed that the extraction efficiency of uranium dropped from 100% at pulp densities of 2.5, 5, 7.5 and 10% to 68% at 12.5% of pulp density. Using RSM, the optimum conditions for uranium bioleaching (12.5% (w/v)) were identified as pH = 1.96, temperature = 30.90 ℃, stirring speed = 158 rpm, 15.7% inoculum, FeSO 4  · 7H 2 O concentration at 13.83 g/L and (NH 4 ) 2 SO 4 concentration at 3.22 g/L which achieved 83% of uranium extraction efficiency. The results of uranium bioleaching experiment using optimized parameter showed 81% uranium extraction during 15 d. The obtained results reveal that using RSM is reliable and appropriate for optimization of parameters involved in the uranium bioleaching process.

Optimized total synthesis, radiolabeling and quality control of [ 68 Ga]-DOTA-Hyd-TRP as an efficient and possible PET radiotracer for GnRH receptor imaging in various tumors is of great interest. DOTA-Hyd-TRP was synthesized using solid phase peptide synthesis followed by conjugation to DOTA using pSCN-Bn-DOTA. [ 68 Ga]-DOTA-Hyd-TRP was prepared using generator-based [ 68 Ga]GaCl 3 and DOTA-Hyd-TRP under optimized conditions for time, temperature, ligand amount, gallium content and column cartridge purification followed by proper formulation. The biodistribution of the tracer in rats was studied using tissue counting up to 120 min. [ 68 Ga]-DOTA-Hyd-TRP was prepared at optimized conditions in 5–7 min at 95 ℃ followed by separation using C 18 cartridge (radiochemical purity ≈ 99 ± 0.88% ITLC, > 99% HPLC, specific activity: 300 ± 15 MBq/nM). The biodistribution of the tracer demonstrated high kidney uptake of the tracer in 10–20 min as well as significant testicular uptake consistent with reported GnRH receptor mappings. Block test studies by triptorelin pretreatment of the animals prior to tracer administration demonstrated significant specific uptake in receptor rich organs including testes and stomach.

Zirconium molybdosilicate (ZrMoSi) gel prepared using 99 Mo radiotracer via peroxo route was used as a base material for 99 Mo/ 99m Tc column generator. The 99m Tc elution yield and 99 Mo breakthrough in the eluate were studied as a function of the pH-value of gel precipitation, gel drying temperature and Zr:Mo:Si molar ratio. Precipitation pH-value of 2, drying temperature of 100 ℃ and Zr:Mo:Si molar ratio of 0.5:0.5:1 were found to be the optimum conditions achieving 99m Tc elution yield of 82% and 99 Mo breakthrough of 1.0E-3%. The gel prepared with the optimum conditions was characterized by BET surface area and pore size analyzer, IR spectroscopy, thermal analysis (TGA and DTA), XRD, XRF and FESEM. Technetium-99m eluted from the optimum ZrMoSi 99 Mo/ 99m Tc generator was found to have a high radiochemical purity (98% as 99m TcO 4 – ) and chemical purity meeting criteria of clinical grade.

The 211 At radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately use of 211 At is limited, because astatine as the heaviest halogen forms weak bond with carbon atoms in the biomolecules which makes 211 At bioconjugates unstable in physiological conditions. In our work we propose a new solution for binding of 211 At which consists of using nanoparticles of titanium dioxide modified with silver atoms as carriers for 211 At. Ag + cations have been absorbed on the nanometer-sized TiO 2 particles (15 and 32 nm) through ion exchange process and were reduced in Tollens' reaction. The obtained TiO 2 -Ag nanoparticles were labeled with 211 At. It was found that labeling yields were almost quantitative under reducing conditions, while under oxidizing conditions they dropped to about 80%. The labeled nanoparticles exhibited very high stability in physiological salt, PBS buffer, solutions of peptides (0.001 M cysteine, 0.001 M glutathione) and in human blood serum. To make TiO 2 /Ag nanoparticles well dispersed in water and biocompatible their surface was modified with a silane coupling agent containing poly(ethyleneglycol) molecules. The developed functionalization approach will allow us to attach biomolecules to the TiO 2 /Ag surface.

The effects of gamma and neutron irradiations on the chemical, optical and structural properties of Bayfol CR-6-2 were investigated. The samples were irradiated by γ -rays from a 60 Co source at various doses ranging between 16 and 900 kGy at room temperature in atmospheric air. For neutrons, an Am-Be neutron facility was used for the sample irradiation in thermal mode which had an activity of 185 GBq. Samples were irradiated with different doses of neutrons ranging from 15.7 to 564.2 mGy. The changes induced were analyzed using UV-Vis and Fourier transform infrared (FTIR) spectrometry. The results demonstrated an occurrence of oxidative degradation, resulting in the formation of carbonyl groups at 1700 cm – 1 . Simultaneous thermo-gravimetric investigation (TGA) has been performed on the samples of 0.3 mm thickness. The results obtained indicate that cross-linking predominates at small neutron doses and main chain scission happens at higher doses.

Twenty two chemical elements were identified by Instrumental neutron activation analysis in Marrubium vulgare (Lamiaceae) a traditional medicine plant, used indigenously in Mediterranean basin to cure several diseases. The precision of the results was assessed by analyzing the certified reference material GBW 07605 (GSV-4) Tea leaves. Results showed that K was the dominant chemical element in studied plant (4.40%). The Ca and Fe mass fractions were also relatively high. However potential toxic elements in this Lamiaceae plant were within the safety limits suggested by WHO/FAO.