Band 103, Heft 9

The cross sections of the 138 Ce( n , 2 n ) 137m,g Ce reactions and their isomeric cross section ratios σ m / σ g were measured at three neutron energies between 13.5 and 14.8 MeV using the activation technique. CeO 2 samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The monoenergetic neutron beams were formed via the 3 H( d ,  n ) 4 He reaction. The activities induced in the reaction products were measured using high-resolution γ -ray spectroscopy. The pure cross section of the ground-state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. The cross sections were also estimated using the nuclear model code, TALYS-1.6 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature data.

New measurements have been undertaken to determine the half-life of 151 Sm. A pure 151 Sm solution was obtained after chemical separation from a samarium solution resulting from the dissolution of an irradiated samarium sample. The concentration of 151 Sm in the solution was measured by mass spectrometry, combined with the isotope dilution technique. The activity of the solution was measured by liquid scintillation counting by six European laboratories as part of an international comparison. These combined results lead to a half-life of T 1/2  = 94.6(6) a.

The kinetics of reductive stripping of Np(VI) by Acetohydroxamic Acid from 30%TBP/kerosene was investigated using a high-speed stirred cell designed by ourselves. The phase separator for sampling was simple and powerful. The interfacial areas of different stirring speeds were determined by microphotograph method at 21 ℃ before the experiments. The effects of the different parameters as well as temperature were investigated systemically. The results showed that, at 21 ℃ the rate equation is − d[Np(VI)]/d t  =  k ( S / V )[Np(VI)] 0.78 [AHA] 0.46 [HNO 3 ] −0.20  −  k ′( S / V )[Np(V)] 2.87 , where k  = (8.7 ± 0.7) × 10 −7  (mol/L) – 0.04 m s – 1 , k ′ = 1.1 ± 0.2 (mol/L) – 2.87  m s – 1 , as c [HNO 3 ] <= 1.0 mol/L, − d[Np(VI)]/d t  =  k ( S / V )[Np(VI)] 0.78 [AHA] 0.46 [HNO 3 ] −1.42  −  k ′( S / V )[Np(V)] 2.87 , where k  = (3.2 ± 0.3) × 10 −7  (mol/L) 1.18  m s – 1 , k ′ = 1.1 ± 0.2(mol/L) – 2.87  m s – 1 as c [HNO 3 ] >= 1.0 mol/L, and S is the interfacial area, V the organic phase volume. The reductive stripping process is controlled by chemical reactions (kinetics regime) taking place at the interface. The apparent activation energy is 13.5 ± 0.2 kJ/mol.

In line with our previously conducted researches, various instrumental methods were applied to evaluate the adsorption features and mechanism of Th 4+ from highly acidic solution (4 M HNO 3 ) by rice and wheat bran. Although the results of cation exchange confirmed the existence of ion-exchange interaction in Th 4+ adsorption, it had a trivial contribution in the biosorption process. The presence of Th 4+ ions on the biomass surface was obviously revealed in SEM images and EDS elemental analysis. Moreover, the linkage of C=O , O–H and N–H functional groups on the biomass surface with Th 4+ ions was clearly represented in the ATR-FTIR spectroscopic analysis. Additionally, desorption studies indicated that ammonium oxalate (>81.3%) and ammonium carbonate (>75.4%) were effective in desorbing Th 4+ from the biomass surface due to strong interactions of hard functional groups of C=O with Th 4+ . The overall observations unfold the fact that electrostatic complexation mechanism is dominant between biomass and Th 4+ ions.

The flotation kinetics of Co(II)-EDTA complexes from aqueous solutions using cetylpyridinium chloride (CPyCl) is studied and discussed in the present work. The effects of many variables on the ultimate recovery and the flotation rate are investigated. The data obtained from solutions of different pH values showed that Co(II)-EDTA complexes are successfully floated at pH 7.8. While at pH 3.4 and 11.2, both the ultimate recovery and the flotation rate are dependent on the concentration of CPyCl. Flotation of Co(II)-EDTA at different air flow rates, CPyCl concentrations and ionic strength showed that the ultimate recovery and the flotation rate are markedly affected. The other parameters (cobalt, EDTA and ethanol concentrations) had no effect on the ultimate recovery, while significantly affected the flotation rate. At the optimum conditions (Co(II) : EDTA = 1:1; CPyCl : Co(II) = 4:1; pH7.8; G  = 25 cm 3 /min), removals more than 99% are achieved for radiocobalt. The classical first-order and the second-order kinetic models are used throughout the work to analyze the experimental kinetic data. At all the studied parameters, the kinetic data of Co(II)-EDTA complexes are better fitted to the classical first-order model.

An early diagnosis of bone metastases is very important for providing a profound decision on a subsequent therapy. In this study, a new agent for SPECT-imaging of bone metastases, 111 In-(4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl) acetic acid ( 111 In-BPAMD) complex has been developed with specific activity of 2.85 TBq/mmol. Radiochemical purity of the radiolabeled complex was checked by instant thin layer chromatography method indicated high radiochemical purity > 95% at the optimal conditions. The complex demonstrated significant stability at room temperature and in human serum at least for 48 h. Hydroxyapatite (HA) binding assay showed high binding ability of the radiolabeled complex even at the low amounts of HA. Also, log  P measurements highlighted the strong hydrophilic nature of the complex. Biodistribution studies as well as planar imaging after injection of the complex into the male Syrian mice showed major accumulation of the labelled compound in the bone tissue. Totally, the obtained results indicated that 111 In-BPAMD has interesting characteristics as an agent for SPECT-imaging of the bone metastases.

In heterogeneous conditions, water soluble Chitosan-Vitamin C Complex (CSVC) is successfully synthesized via the ionic interaction between γ -degraded CS and VC. Chitosan (CS) of low molecular weight (MW) is prepared using γ -irradiation method. The coupling of CS and vitamin C (VC) is carried out by the chemical treatment of VC with the γ -degraded CS. The formation of CSVC complex instead of physical mixture is confirmed by FT-IR and UV spectrometry. Characterization by transmission electron microscope (TEM) and dynamic light scattering (DLS) shows the formation of a nanostructure in 40 nm range. The preparation of labeled CSVC was performed using chloramines-T oxidation method. The labeling feasibility of CSVC nanostructure by Iodine-125 ( 125 I) is investigated. The optimized conditions of labeling are thought to be 50 μg of oxidizing agent, pH 3, and one minute reaction time. The Biodistribution activity of 125 I radiolabeled CSVC nanostructure ( 125 I-CSVC) is examined on a group of different ascites tumor bearing mice. Calculation of the biodistribution percentages shows that the tumor, liver, and kidney are the targeting organs of 125 I-CSVC nanostructure.

Instrumental neutron-activation analysis (INAA) was applied to estimate trace contaminations in polyethylene (PE) used as a neutron shield for low background setup of the EDELWEISS Dark Matter search experiment. PE samples with masses of 1–10 grams each were irradiated at the WWR-SM nuclear reactor by neutron flux of 1 · 10 14  n/(cm 2  s) for 5–48 h. The radioactivity was measured by high-resolution γ -ray spectrometry. In PE samples of two types, more than 30 trace elements were determined at a concentration level of 10 −5 to 10 – 11  g/g.