We report the high-pressure synthesis of novel superconductor MgB 2 and some related compounds. The superconducting transition temperature of our samples of MgB 2 is found to be 36.6 K. The MgB 2 lattice parameters determined via X-ray diffraction are in excellent agreement with results of our ab initio calculations. The TDPAC measurements of 111 Cd quadrupole frequency ν Q demonstrate a small increase in ν Q with decreasing temperature from T room to T He .The electric field gradient V zz at the B site calculated from first principles is in fair agreement with V zz obtained from 11 B NMR spectra of MgB 2 reported in the literature. It is also very close to V zz found in our 111 Cd TDPAC experiments, which suggests that the 111 Cd probe substitutes for boron in the MgB 2 lattice.
Fast progressing immuno-PET asks to explore new radionuclides. One of the promising candidates is 90 Nb. It has a half-life of 14.6 h that allows visualizing and quantifying biological processes with medium and slow kinetics, such as tumor accumulation of antibodies and antibodies fragments or drug delivery systems and nanoparticles. 90 Nb exhibits a positron branching of 53% and an average kinetic energy of emitted positrons of mean = 0.35 MeV. Currently, radionuclide production routes and Nb V labeling techniques are explored to turn this radionuclide into a useful imaging probe. However, efficient separation of 90 Nb from irradiated targets remains in challenge.Ion exchange based separation of 90 Nb from zirconium targets was investigated in systems AG 1 × 8 -HCl/H 2 O 2 and UTEVA-HCl. 95 Nb ( 1/2 = 35.0 d), 95 Zr ( 1/2 = 64.0 d) and 92m Nb ( 1/2 = 10.15 d) were chosen for studies on distribution coefficients. Separation after AG 1 × 8 anion exchange yields 99% of 90/95 Nb. Subsequent use of a solidphase extraction step on UTEVA resin further decontaminates 90/95 Nb from traces of zirconium with yields 95% of 90/95 Nb.A semi-automated separation takes one hour to obtain an overall recovery of 90/95 Nb of 90%. The amount of Zr was reduced by factor of 10 8 . The selected separation provides rapid preparation (< 1 h) of high purity 90 Nb appropriate for the synthesis of 90 Nb-radiopharmaceuticals, relevant for purposes of immuno-PET. Applying the radioniobium obtained, 90/95 Nb-labeling of a monoclonal antibody (rituximab) modified with desferrioxamine achieved labeling yields of > 90% after 1 h incubation at room temperature.
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