Volume 96, Issue 7 -

Semi-empirical systematics of the ( p , n ) reaction cross-section was obtained at incident proton energies 7.5 MeV, 12.4 MeV and 24.8 MeV. Systematics is based on analytical formulas derived using the pre-equilibrium exciton model, evaporation model and semi-empirical mass formula Parameters of systematics were fitted to the data obtained from the analysis of available measured ( p , n ) reaction cross-section.

Copper-64 ( t ½ = 12.7 h) is a promising cancer treatment radiotherapy agent and combines positron emission tomography (PET). It was produced utilizing the 64 Ni(p,n) 64 Cu nuclear reaction channel. Natural nickel was electroplated successfully, 48 μm thick, onto a gold-coated copper backing slab. Bombardment of nickel plated target was performed with 16 MeV protons at a current of 200 μA. Copper-64 together with copper-61 was separated from Ni and other non-isotopic impurities by ion exchange chromatography. The method of separation of radiocopper has been improved.

A task-specific ionic liquid, protonated 1-carboxy- N , N , N -trimethylmethanaminium bis(trifluoromethylsulfonyl)imide trivially known as protonated betaine bis(trifluoromethylsulfonyl)-imide ([Hbet][NTf 2 ]) was prepared and the dissolution of uranium oxides, UO 3 , UO 2 and U 3 O 8 in it was studied. Dissolution of UO 3 in [Hbet][NTf 2 ] was very rapid and the saturation solubility of uranium was found to be 15 wt. % at 373 K. In contrast, dissolution of UO 2 was sluggish and it was facilitated only by the oxidation of UO 2 to UO 2 2+ . U 3 O 8 was insoluble up to 453 K. A new procedure was developed for the individual separation of uranium oxides using [Hbet][NTf 2 ] based on differences in solubilities. The electrochemical behavior of U(VI) in the resultant solution was investigated by cyclic voltammetry at glassy carbon working electrode at 373 K. A surge in the cathodic peak current at -0.48 V ( vs . Fc/Fc + ) was due to the reduction of U(VI) to U(V) and the corresponding anodic peak current was observed at a potential of 0.64 V. Increasing the potential sweeping rate increases the peak current and shifts the peak potential negatively indicating the irreversible electroreduction of U(VI) in [Hbet][NTf 2 ]. The diffusion coefficient of U(VI) in [Hbet][NTf 2 ] was determined to be of the order of ∼10 −8 cm 2 /s.

Polynuclear hydroxide complexes play an important role for the hydrolysis of tetravalent thorium ions in aqueous solution, in particular for Th(IV) concentrations exceeding some [Th(IV)]=10 −4 M. Consequently, these polymers must be considered when describing hydrolysis of Th(IV) or dissolution processes of Th(IV) solids. In the past, considerable efforts were made to obtain equilibrium formation constants of these polymers and different stoichiometries for dimers, tetramers and hexamers have been suggested. However, most information was obtained from indirect methods, in particular, from potentiometric titrations. In the present work, we present an approach of directly quantifying polymeric metal hydroxide complexes in solution. By nano-electrospray mass-spectrometry the degrees of polymerization, i.e. the numbers of Th 4+ ions and the numbers of hydroxide ligands, and as a consequence, also the charges of the complexes are measured. All mono- and polynuclear species which are present in solution are quantified simultaneously down to species contributing less than 0.1% of the total [Th(IV)] concentration. Solutions of [Th(IV)]=6×10 −6 –10 −1 M are investigated in HCl at [H + ]=10 −4 –0.1 M. More than 30 different polymeric complexes are observed with the general trend of increasing number of hydroxide ligands with decreasing acidity. A surprising finding is the presence of the pentamer Th 5 (OH) y z + , which was not described in the literature before. With decreasing Th(IV) concentration the stability field of polymers narrows continuously until polymers can no longer be detected below [Th(IV)]=10 −5 M.

The preferential accumulation of porphyrins in malignant tumor cells has been adequately documented. Hence, porphyrin derivatives radiolabeled with a suitable therapeutic radionuclide could be envisaged as potential agents for targeted tumor radiotherapy. Working in this direction, we have radiolabeled a porphyrin derivative, namely, 5,10,15,20-tetrakis[3,4-bis(carboethoxymethyleneoxy)phenyl]-porphyrin, synthesized in-house, with 109 Pd [ E β(max) =1.12 MeV, E γ =88 keV 3.6(%), T 1/2 = 13.7 h]. The envisaged rationale towards designing of this agent is based on the assumption that 109 Pd would complex with the tetrapyrrole donor array constituting the porphyrin core, thereby providing a highly stable chelated complex, and the peripheral ester groups would impart optimum lipophilicity needed for sufficiently high tumor accumulation and retention therein. 109 Pd was produced with a specific activity of ∼1.85 GBq/mg and radionuclidic purity of 100% by the thermal neutron bombardment of enriched (98% in 108 Pd) metallic Pd target at a flux of 3×10 13 n/cm 2 s 1 for 3 d. The porphyrin derivative was synthesized by a multi-step reaction and characterized by normal spectroscopic techniques. 109 Pd complex of the synthesized porphyrin derivative was prepared with excellent radiochemical purity (>98%) and the complex was observed to be stable upto 24 h at room temperature. Biodistribution studies carried out in Swiss mice bearing fibrosarcoma tumors revealed good tumor uptake [(5.28±1.46)% injected activity (IA)/g] within 30 min post-injection (p.i.). The complex exhibited favorable tumor/blood and tumor/muscle ratios [1.69±0.23 and 5.00±1.54, respectively at 3 h p.i.], albeit with high liver uptake throughout the time of study (>20% IA).

β-1–24-corticotrophin was successively labeled with [ 67 Ga]-gallium chloride after residulation with freshly prepared cyclic DTPA-dianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a β-1–24-corticotrophin pharmaceutical solution (1 mg/mL, pH=6.5) to a glass tube pre-coated with DTPA-dianhydride (0.01 mg) at 25 °C with continuous mild stirring for 30 min. Radio-thin layer chromatography showed an overall radiochemical purity of >90% at optimized conditions after labeling. HPLC showed a radiochemical purity more than 95% (specific activity =300–500 MBq/mg, labeling efficiency 77%). The stability of the radioconjugate was tested in presence of human serum at 37 °C. Preliminary in vivo studies in normal rats were performed to determine the biodistribution of the radioimmunoconjugate up to 30 min. Lungs showed to have the major tracer uptake which is consistent with the natural distribution of ACTH receptors in human body. Pretreatment of animals with cold peptide following labeled compound administration reduced lung uptake at least 10 and 3 times after 15 and 30 min, respectively, as well as significant decrease in adrenal uptake after 15 min. These data support the specific receptor binding of the radiolabeled compound. This tracer can be used in detection of ACTH receptor in lung and adrenal malignancies.

Various types of liquid radioactive wastes are released from different nuclear activities. The treatment efficiencies of these wastes depend highly on the physical and chemical composition of each waste such as pH, TDS and electrical conductivity. The treatment efficiency of some radionuclides with different valency states (such as 134 Cs, 65 Zn, 60 Co and 152+154 Eu) was tested based on the absorption capacity of cationic exchanger (KY-2) functionlized with polystyrene sulphonic group. The competitive adsorption on cationic exchanger was investigated by mono radionuclide and multi radionuclides wastes. The influence of the presence of various anionic complexants in the rad-waste on the adsorption capacity and hence the treatment efficiency was quantitatively studied using weakly base aminated anionic exchanger (AN-31). The enhancement in decontamination factor of each radionuclide is mostly attributed to the high adsorption capacity of the cationic resin in addition to the complexation capability of the radionuclide with the different complexant existed in the waste solution. The complex formation improved the decontamination factor through indirect adsorption of the anionic species on the subsequent anionic exchanger during the treatment process. The results showed that the removal percentages are around 50% for 134 Cs, 60 Co, 65 Zn and 152,154 Eu, without complexant compound. Significant enhancements of the removal percentages >85% were obtained for 60 Co, 65 Zn and 152,154 Eu, respectively, on addition of manganese sulphate while maximum removal percentage (75.3±0.7%) is obtained for 134 Cs when using 0.1 M citric acid as a complexing agent.