Volume 90, Issue 4 -

Formation cross sections of about forty fission products have been determined using recoil catcher technique followed by off line gamma-ray spectrometry in 7 Li induced fission of 232 Th at E lab = 41.9, 36.6 and 31.4 MeV. The measured data have been used to deduce charge and mass distributions. Mass distribution is found to be asymmetric at all the three energies. Cross sections of evaporation residues formed in both transfer reactions ( 232,233,234 Pa) as well as in complete fusion ( 234 Np), have also been measured. The measured evaporation residue cross sections and the decay probabilities of target like nuclei ( 233,234,235 Pa) formed in the various transfer reactions, as calculated by PACE2, have been used to estimate the transfer induced fission cross sections. The data indicated that the magnitude of transfer induced fission is very small.

In anion exchange resin systems with LiCl-aqueous and LiCl-(H 2 O + CH 3 OH) solutions, the extent of chloro complexation of M(III) (M = Eu, Cm) was estimated from inner-sphere hydration number ( N H2O ), i.e. , the number of water molecules in the first coordination sphere of M(III) and from peak area ratio ( A 2 / A 1 ) of 5 D 0 → 7 F 2 transition ( A 2 ) to 5 D 0 → 7 F 1 transition ( A 1 ) in emission spectrum of Eu(III), which reflects the ligand environment both in the inner- and outer-spheres of Eu(III). The N H2O of M(III) both in the solution and resin phases decreased with an increase of LiCl and CH 3 OH concentrations, indicating the formation of an inner-sphere M(III)-chloro complex. From the comparison of N H2O between the both phases, it was found that the extent of the inner-sphere chloro complexation of M(III) in the resin phase is higher than that in the solution phase. The A 2 / A 1 ratio in the both phases increased with an increase of interaction of Eu(III) with Cl − , which are well correlated with the results of N H2O . The sorption equilibrium of M(III) was discussed by comparing the extent of the chloro complexation with the distribution coefficient.

The separation of plutonium from marine sediments (IAEA-135 reference material) by solvent extraction and determination with Photon Electron Rejecting Liquid Alpha Spectrometry (PERALS ® ) has been performed. Two extraction schemes, TOANO 3 and HDEHP, were compared for the separation of plutonium, uranium, thorium and americium from the matrix components. The TOANO 3 separation method showed plutonium recovery of 85% with an accuracy of ±20%, while for the HDEHP separation the plutonium recovery was only 9.3%. Minimum detectable activities of plutonium for a counting time of 120000 seconds for 0.25 g sample material were 0.18 Bq/kg for TOANO 3 and 1.62 Bq/kg for HDEHP separation methods, respectively.

The extraction of trivalent lanthanide (Sm 3+ , Eu 3+ ) and actinide (Am 3+ , Cm 3+ ) cations from 1.0 M NaNO 3 into n -dodecane solutions of bis(2,4,4-trimethylpentyl)phosphinic acid (HC272), bis(2,4,4-trimethylpentyl)monothiophosphinic acid (HC302), and bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HC301) is reported. In each case, the dependence of the distribution ratios on the total extractant concentration is approximately second power. Using NMR, the dimerization constant of HC301 is determined to be 0.67 ± 0.06 at 25.0 °C in deuterated n -heptane, implying that the average aggregation of the extractant changes greatly across the extractant concentration range studied. When the effect of aggregation is considered for each of the extractants, the stoichiometries of the extracted complexes are found to be M(H(C272) 2 ) 3 , M(C302) 3 , and M(C301) 3 .

Purified humic acid has been covalently bound on activated epoxy silica gel particles. Determination of physical properties and chemical properties was conducted in order to characterize the material at different stages of the preparation. FTIR spectra and the PEC of the surface bound humic acid is very similar to that of humic acid starting material. This shows that the humic acid was not deteriorated during the surface binding process. This humic gel can be used as an analogue for sediment associated humic acid, with the advantage that covalently bound humic acid does not desorb, and thus allows for simple species separation between non-complexed and humic bound metal ions in batch and column experiments.

Three new quinoline derivatives were synthesised and characterized. These compounds were found to be insoluble in water and different acids such as HNO 3 , HCl until 6 M and soluble in NaOH at 2 M concentration. Chloroform was found to be the suitable solvent for quinoline derivatives. The extraction of Ag from nitric acid by 8-methyl-2,4-dithiol-quinoline (1H) (MDTQ), 4-chloro-8-methyl-quinoline (1H) thione (CMTQ) and 3-formyl-4-hydroxy N-methyl 2(H) quinoline (FHMQ) has been investigated. The effects of shaking time, nitric acid concentration, metal ion concentration and the concentration of extractant were studied. The results showed that the distribution ratio of Ag decreased with increase in the nitric acid and metal concentration, and increased by increasing the extractant concentration. It was found that an equilibrium time of 10 min was required to reach equilibrium. The results showed that (MDTQ) is very selective for the separation of Ag.

For quantitative determination of in vivo dosimetry of 90 Y-labeled radiotherapeuticals by means of PET, the positron emitting analogue yttrium-86 was produced at a low energy (“medical”) cyclotron via the known 86 Sr( p , n ) 86 Y reaction. Using 200 mg of 86 SrCO 3 (enrichment 95.6%) and protons of 15.1 MeV energy, average yields of 86 Y of 48 ± 8 MBq/µA h were produced. After dissolution of 86 SrCO 3 in 3 ml of 0.6 N HNO 3 , 86 Y was deposited in a simple and highly efficient electrochemical two-step procedure onto a platinum cathode at 450 mA (= 20 mA/cm 2 ). The isotope was finally removed from the electrode by 100–300 µl of 0.5–1.0 N HCl or 0.3–0.6 N HNO 3 resulting in an overall recovery of 88 ± 6% (corrected for decay). Up to 1 GBq of 86 Y with high radionuclidic and radiochemical purity were obtained after a 2.5 h irradiation and a radiochemical separation time of 2 h. An ICP/AES analysis of the separated fraction showed a very small amount of strontium (< 0.1 ppm). The chemical purity of 86 Y, essential for efficient labeling, was successfully demonstrated by means of complex formation with DOTA and a DOTA-conjugated peptide, exhibiting labeling yields higher than 98%.

Closo -dodecaborate dianion is a three-dimensional aromatic inorganic molecule, which can be easily halogenated forming a stable halogen-boron bond. Derivatives of closo -dodecaborate were considered as a convenient chemical form of delivery of enriched 10 B to malignant tumors for boron neutron capture therapy (BNCT). Some properties of closo -dodecaborate (hydrophilicity, strength of halogen-boron bond, charge at lysosomal pH) make it attractive as a potential prosthetic group for attachment of radioactive halogens to tumor-targeting proteins. Bromine radioisotopes possess a variety of useful nuclear characteristics, and can be used in different areas of clinical diagnostics and therapy. In this work, a basic chemistry of closo -dodecaborate radiobromination was studied. It was found, that di(triethylamonium) dodecahydro- closo -dodecaborate can be labelled in high yield, more then 90%, in a wide pH range. By decreasing the pH, the bromination can be directed to closo -dodecaborate in the presence of phenolic compounds. The results of the study indicate a possibility of using the radioactive bromine label for investigation of pharmacokinetics of boronated compounds for BNCT.

A water-soluble polymer, polyethyleneimine functionalised with methylene phosphonate groups (PEI-MP) and labelled with 99m Tc, has shown selective uptake into bone tumours. Apparent formation constants for the complexation of important blood plasma metal-ions and metal-ions of radionuclides used in therapeutic radiopharmaceuticals (excluding Tc) with PEI-MP were measured potentiometrically. These were added to the ECCLES data base in order to construct a blood plasma model for PEI-MP. From this model it could be predicted that the polymer would not deliver the therapeutic radionuclides 153 Sm, 166 Ho, 212 Pb, 213 Pb and 89 Sr to bone. This was clinically verified for 153 Sm. However good uptake of 99m Tc-PEI-MP could be demonstrated in dogs. Due to the similar chemistry of Re as compared to Tc, it can be expected that PEI-MP labelled with 186 Re or 188 Re could result in effective therapeutic radiopharmaceuticals for bone cancer.