Band 101, Heft 9

Cross sections for (γ, n) reaction at bremsstrahlung end point energies of 10 and 12.5MeV on niobium have been measured by the activation technique. Induced activities were measured by a high-resolution γ-ray spectrometer with a high-purity germanium (HPGe) detector. Theoretically the (γ, n) cross-section of 93 Nb as a function of photon energies were also calculated using TALYS 1.4 computer code. We compared the measured data with the flux weighted average values from the available literature data based on experiments with mono-energetic photons and the theoretical calculation by the model code TALYS 1.4. The experimental values are found to be in good agreement with the theoretical value from TALYS 1.4 but are slightly higher than the flux-weighted values from mono-energetic photons

The design of a new type of electroreduction mixer-settler for the partitioning of uranium and plutonium during the Purex process, which is featured with E-shaped cathodes and U-shaped anodes in settling chamber, is described and the operational results achieved using this equipment are presented. The results show that this new type of mixer-settler has excellent separation performances. The flow rate of organic feed solution is 3 mL / min and the flow ratio of feed solution (1BF) to aqueous back extraction stream (1BX) and to organic wash stream (1BS) is 4 / 1 / 1. For an organic feed of 84 g / L uranium and 1 . 40 ⁓ 2 . 64 g / L plutonium, both the separation factor of plutonium from uranium and that of uranium from plutonium are apparently higher than 10 4

The influence of 14 C-labeled M42 humic acid (HA) on the interaction between neptunium(V) and natural clay rock (Opalinus Clay (OPA), Switzerland) has been investigated in batch sorption and diffusion experiments under ambient air conditions. The effect of 10 mg/L HA on the diffusion of 8 μM Np(V) in OPA has been investigated in synthetic OPA pore water (pH 7.6, I = 0.4M) for the first time. Batch sorption experiments as a function of solid-to-liquid ratio (4-20 g/L) were performed under same experimental conditions to compare distribution coefficients obtained from both diffusion and sorption experiments. These experiments showed only a slight influence of HA on Np(V) uptake by OPA in both cases and provided comparable distribution coefficients (presence of HA: K d = 22-32 L/kg, absence of HA: K d = 30-46 L/kg). As it is known that the interactions of humic substances with actinides depend on various experimental parameters, the effect of HA on Np(V) sorption on 15 g/L OPA was also investigated as a function of pH (6-10) and initial Np concentration (8 μM and 7 pM). A saturated calcite solution was used as a background electrolyte in this case to prevent any dissolution of calcite contained in OPA at low pH. The results showed that the presence of M42 HA increases Np(V) sorption at pH < 7 while lower sorption was obtained above pH 8. Higher sorption at acidic pH can be attributed to strong sorption of HA which increases the number of sorption sites, while sorption decreases at higher pH probably due to formation of soluble ternary neptunium humate carbonate species.

Sorption plays a major role in the safety assessment of nuclear waste disposal. In the present theoretical study we focused on understanding the interaction of trivalent lanthanides and actinides (La 3+ , Eu 3+ and Cm 3+ ) with the corundum (110) surface. Optimization of the structures were carried out using density functional theory with different basis sets. Additionally, Møller-Plesset perturbation theory of second order was used for single point energy calculations. We studied the structure of different inner-sphere complexes depending on the surface deprotonation and the number of water molecules in the first coordination shell. The most likely structure of the inner-sphere complex (tri- or tetradentate) was predicted. For the calculations we used a cluster model for the surface. By deprotonating the cluster a chemical environment at elevated pH values was mimicked. Our calculations predict the highest stability for a tetradentate inner-sphere surface complexes with five water molecules remaining in the first coordination sphere of the metal ions. The formation of the inner-sphere complexes is favored when a coordination takes place with at most one deprotonated surface aluminol group located beneath the inner-sphere complex. The mutual interaction between sorbing metal ions at the surface is studied as well. The minimal possible distance between two inner-sphere sorbed metal ions at the surface was determined to be 530 pm.

A new (radio)iodinated AMPA receptor ligand has been developed and pharmacologically evaluated in vitro and ex vivo using rodents. The new radioligand was directly labeled by electrophilic radioiodo-destannylation with iodine- 131 in high radiochemical yields of 97% within 2 min. The new radioligand showed an excellent initial brain uptake of 2.1%ID/g at 10 min post injection, but a fast wash-out reduced the uptake by about 10-fold at 60 min post injection. Due to high nonspecific binding accompanied with a uniform distribution in brain tissue, however, the new radiotracer appears not suitable for AMPA receptor imaging in vivo.

In this study, bevacizumab was successively labeled with 111 In-InCl 3 after conjugation with DOTA-NHS-ester followed by molecular filtration and determination of the average number ofDOTAconjugated per mAb (6 : 1) by spectrophotometric method. Radiochemical purity ( > 97%, measured by ITLC and HPLC), integrity of protein after radiolabeling (gel electrophoresis) and stability of 111 In-DOTA-Bevacizumab (in final formulation, human serum, liver / kidney homogenates) were determined in 24-72 h as well as biodistribution studies in wild-type rats and human colon cancer (SW-480) bearing mice. The accumulation of the radiolabeled antibody was consistent with the former reported Bevacizumab conjugates. Significant tumor uptake (8%) was observed at 72 h p.i. Tumor / muscle uptake ratios were 2.6 (24 h), 9.74 (48 h) and 25 (72 h). 111 In- DOTA-Bevacizumab was prepared as a SPECT molecular imaging agent for diagnosis and follow-up of vascular endothelial growth factor A (VEGF-A) expression in oncology.

It is known that medicinal plants like olive have biological activities due to their flavonoid content such as olueropein, tyrosol, hydroxytyrosol etc. In current study, hydroxytrosol (HT) which is one of the major phenolic compounds in olive, olive leaves and olive oil, was isolated after methanol extraction and purification of olive leaves which are grown in the northern Anatolia region of Turkey. The isolated HT was radiolabeled with 131 I ( 131 I-HT) and the bioaffinity of this radiolabeled component of olive leaves extract was investigated by using in vivo/in vitro methods. It was found that HT could be radiolabeled with 131 I in yields of 95.6±4.4% (n = 8), and in vivo studies showed that 131 I-HT is taken up by urinary bladder, stomach, small intestine, large intestine, breast and prostate. Significant incorporation of activity was observed in cell lines via in vitro studies.

Retaining radioactive daughter products at a clinically relevant target site remains one of the major challenges in development of in vivo α generators with radionuclides such as 225 Ac and 223 Ra. In this work, we examine the ability of layered nanoparticle constructs to retain 225 Ac and the first decay daughter, 221 Fr. Actinium-225 is cocrystalized in a lanthanide phosphate nanoparticle consisting of varying amounts of La and Gd. Additional lanthanide phosphate layers improve retention capability while an outer layer of gold facilitates the attachment of targeting moieties for in vivo use. Retention of 225 Ac in the nanoparticles is near quantitative while the 221 Fr retention varies from 60-89% as a function of time, the number of layers, and nanoparticle composition. Decay corrected radiochemical yield in the multi-shell syntheses are high (76%) and comparable to or better than existing delivery approaches.

Miniature neutron source reactors (MNSR) are known for their stable neutron flux characteristics and are mostly employed for neutron activation analysis (NAA). Interfering reactions are sometimes observed in instrumental neutron activation analysis (INAA). Failure to correct for these interferences produces significant systematic positive errors. This paper provides correction factors for the interferences caused by the threshold reactions and fission products of 235 U. These factors were calculated by using the experimentally determined thermal, epithermal and fast neutron flux and epithermal neutron flux shape factor and the nuclear data from the literature using the Høgdahl convention. Correction factors were calculated for ( n, p ) and ( n, α ) reactions for the most commonly observed radionuclides in INAA. Similarly, correction factors for uranium fission were calculated for 9 elements (Ce, Ba, La, Mo, Nd, Pd, Ru, Sm and Zr). The correction factors were validated by analyzing different materials. A comparison of uranium fission factors with those published in the literature showed a good agreement except for 97 Zr, 99 Mo and 131 Ba which is due to difference in the flux characteristics. In general, these factors can be used with confidence.