Band 110, Heft 10

In this study we investigated the production cross sections of nat Cu(p, x) 63,65 Zn, nat Ti(p, x) 48 V, nat Ni(p, x) 55 Co, 61 Cu and nat Cu(α, x) 66,67,68 Ga, nat Ti(α, x) 49,51 Cr, nat Ni(α, x) 63,65 Zn reactions in the low energy range using the foil activation technique. The samples were activated in vacuum at 5 MV tandem (Pelletron) accelerator installed at National Centre for Physics (NCP), Islamabad, Pakistan. The reaction products were identified with the help of off-line gamma ray spectroscopy system connected with Genie 2000 software. The data analysis revealed the production of different radioisotopes that have valuable importance in monitoring charged-particle beams and medical applications. The measured results were verified by comparing them with earlier evaluated data as well as with the theoretical values given in the TENDL-library based on TALYS-1.9 code calculations.

This work exhibits the very first experimentally determined cross sections for 26 Al and 41 Ca as proton-induced spallation products of metallic vanadium targets. Additionally, the authors describe a radiochemical separation of 26 Al and 41 Ca from the vanadium matrix and present the theoretically calculated cross-section values as a reference for the experimental ones.

The effects of feeding location on crystals size and distribution, precipitation percentage of Pu(IV) oxalate were investigated in a vortex continuous precipitator when the apparent average residence time was 25 min at 50 °C. The results showed that when oxalic acid was into the free vortex zone and Pu(IV) nitrate solution was into the forced vortex one, the VMD of the particles near the outlet of the precipitator increased from 36.8 ± 1.2 µm to 45.8 ± 2.1 µm, the precipitation percentage of Pu(IV) oxalate from 97.90% ± 1.0–99.79% ± 0.05%, compared with another feeding location, both oxalic acid and Pu(IV) nitrate solution into the forced vortex zone. The two feeding methods could both prevent Pu(IV) oxalate nuclei contacting the inner wall of the precipitator during nucleation. The results showed agglomeration happened during crystals growth even under stirring. Both local supersaturations and agglomeration decided particles size distribution and the average size of Pu(IV) oxalate.

The existence of Pb which formed polyatomic ions such as PbCl + , PbAr + would interfere the determination of ultra-trace Am by ICP-MS. An extraction chromatography method for the removal of Pb interference was provided in this work to improve the determination accuracy of ultra-trace Am by ICP-MS. In this study, Sr resin was applied to separate Am and Pb because of the great difference between Am and Pb on adsorption ability. The variable parameters including nitric acid concentration, loading volume, column height and loading amount were investigated to optimize the separation conditions for high recovery of Am ( R (Am)) as well as high decontamination factor of Pb (DF(Pb)). The optimal separation method was recommended in the study with the recovery of Am over 99% and the decontamination factor of Pb over 2 × 10 5 . Moreover, the method was successfully applied to the analysis of 241 Am in the simulated samples.

In this study, for the first time the organic gas steam-liquid extraction (OGS-LE) method is used as a simple, efficient and scalable to industrial application technique for the extraction and separation of uranium (VI) from aqueous samples. OGS-LE is done by a special handmade extraction cell. In this method, the organic solvent vapor produced in the evaporator unit is introduced into the aqueous sample by using nitrogen as a carrier gas. By inserting the vapor bubbles of the organic solvent into the aqueous sample, the organic solvent dissolves in water and the organic solvent concentration in water reaches supersaturation. During this process, equilibrium occurs between the dissolved organic solvent and the insoluble organic solvent, and it is collected on top of the aqueous phase. Uranium has been extracted with cyanex 272 and tetrabutylammonium bromide (TBAB) as extractant into n-heptane from the alkaline aqueous media by the OGS-LE method. Cyanex 272 and TBAB were used as the complexing ligand and the ion pairing reagent, respectively. The mechanism of extraction was proposed depending on the deprotonating of cyanex 272 and ionic interaction with the quaternary ammonium bases. Face Central Composite Design (FCCD) was used to evaluate the effect of various factors. Under the optimized conditions, uranium extraction could be completed in a single stage with the extraction efficiency of more than 90% from an aqueous solution containing alkali, alkaline Earth and transition metal ions. The precision, obtained by performing five replicates under the optimized conditions, was 90.12% ± 0.75% (percentage of extraction ± RSD).

Extraction and carrier mediated transport of thorium (IV) ions through bulk liquid membrane containing di-2-ethylhexyl phosphoric acid (DEHPA) in kerosene as metal ion carrier. The feed comprised of thorium (IV) ions solutions containing various concentrations of hydrochloric acid, while sulfuric acid solutions of different concentrations are used as a stripping agent. Various parameters about thorium (IV) ion extraction and transport were investigated: the feed solution acidity, initial metal ions aqueous solution concentration, carrier concentration and stripping agent concentration. More than 85% thorium (IV) is recovered in 960 min using 0.2 M DEHPA/kerosene as carrier and 1.5 M H 2 SO 4 as stripping agent from the 0.0001 M HCl solution containing 50 mg L −1 thorium (IV) as feed. Assuming a consecutive, irreversible extraction and back-extraction (stripping) reactions a simple kinetic model was proposed for estimating the reaction rate constant or reaction rate coefficient under the investigated experimental conditions. The activation energy values of extraction and back-extraction reactions were calculated to be 29.94 kJ mol −1 and 20.55 kJ mol −1 , respectively, which indicates that the extraction process was controlled by the mixed regime (both kinetic and diffusion), and the back-extraction process was mainly controlled by diffusion process.

In this study, concerning the advantages of rhenium-188 over other therapeutic radionuclides, such as its stock availability from  188 W/ 188 Re generator and radiolabeled peptide therapy in the treatment of patients with widespread disease, preparation and quality control of  188 Re-HYNIC-TOC were studied. Optimized conditions for radiolabeling of HYNIC-TOC with  188 Re were assessed by several experiments.  188 Re-HYNIC-TOC was prepared with radiochemical purity >97%. The radiolabelled compound showed high stability both in PBS buffer and in human serum even after 24 h. Biodistribution of the complex in male Wistar rats was examined up to 24 h after intravenous injection and indicated fast blood clearance and significant accumulation in the kidney. The radiation absorbed dose assessment resource (RADAR) method was used to estimate the equivalent and effective absorbed dose of human organs. Kidney received the absorbed dose of 0.72 mSv/MBq, the highest estimated amount, after injection of the complex. The results showed fast preparation, easy quality control, and relatively similar biodistribution of  188 Re-HYNIC-TOC to other peptides. This complex can be considered as an agent for the treatment of patients with medium-sized tumors expressing somatostatin receptors. However, more biological studies are still needed.

Chemical and radiochemical studies have been carried out on flower samples of the plant Tecoma stans (L) Juss. Ex Kunth which is now increasingly cultivated all over Egypt because of its many useful properties. This plant is considered as an important source of many medicinal phytochemicals. The flower samples analyzed were collected from plants cultivated at different sites in some governorates in Egypt. Nondestructive instrumental neutron activation analysis (INAA) technique has been performed in order to determine the inorganic elemental contents of these flower samples. INAA has been carried out under chosen irradiation and decay time conditions. Thus, the irradiations have been for under short and long times. The analyzed elements were: Ag, Al, Au, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Sb, Sc, Se, Sm, Th, Ti, U, V, Yb, and Zn. Some elements were major or minor elements whereas others were trace elements. 17 elements were found in all analyzed samples where others were only found in some samples. The determined concentrations of some of the analyzed elements were much higher than those found in soil or earth crust, which may indicate that these elements are important. Generally, plants have high tendency to concentrate elements from sites. On the other hand, some other elements are considered toxic, e.g. Ag, Br, Co, Cr, and Sb. Three certified slandered reference materials have been used to assure the accuracy and precision of the INAA technique; these are IAEA soil-7, IAEA 140/TM (seaweed) and IAEA-155 (whey).