In order to clarify the effect of tritium(3H or T)on both the ecosystem and the reactivity of compounds including H atom(s), the hydrogen-isotope exchange reaction (T-for-H exchange reaction) between each benzaldehyde derivative and tritium-labeled poly (vinyl alcohol) was observed in the range of 50 to 90°C. As a result, the radioactivity of the compounds increased with the reaction time. Applying the A"-McKay plot method to the observed data, the rate constants(k) of the functional group in each compound were obtained. Comparing these k with each other, the following six matters have been clarified in the reaction. (1)The reactivity of benzaldehyde derivatives depends on temperature. (2)The order of the temperature dependence in the reactivity of the fluorobenzaldehyde tends to o-substitute > m-substitute > p-substitute, and that in the reactivity of the chlorobenzaldehyde tends to m-substitute > o-substitute > p-substitute. (3)The order of reactivity in each chlorobenzaldehyde derivatives tends to o-position > m-position > p-position. (4)The reactivity of the formyl group in the benzaldehyde derivative can be estimated by applying both the A"-McKay plot method and the Hammett rule. (5)The method used in this work is useful for evaluating the influence of T on environment.
The rapid analysis method of 89Sr and 90Sr in effluent has been investigated using a liquid scintillation counter, which could distinguish the difference of β energy. Analyzed the imitation effluent samples including interference radionuclides such as 54Mn, 60Co, 106Ru, 137Cs, the good accuracy, precision and chemical recovery were obtained in the analyses. It took only 3 or 4 days to analyze them by this method, though it took a few weeks by the conventional methods. These facts made it sure that this method was worth enough for the analysis of 89Sr and 90Sr in effluent.
In this review a list of commercially available 99mTc-labeled radiopharmaceuticals was presented, and the significance to use them clinically was described in the face of this difficult situation due to the 99mTc shortage. The supply history and the chronological change in the sales of 99Mo/99mTc generators in Japan were also described. I emphasize the importance of a nationwide spread of dedicated SPECT/CT equipments, which provide not only a simultaneous acquisition of dual tracers, but also information on both function and morphology. The present issues to address this difficult situation were discussed, referring to the summary of the OECD/NEA workshop held in Paris and the press conference at the 56th SNM annual meeting held in Toronto. The results of a questionnaire survey conducted in Saitama prefecture suggested the procedures, such as a domestic self-supply of 99Mo, to resolve the issues related to the shortage. In addition, the ongoing JMTR project regarding self-supply of 99Mo was described. Based on a reliable supply of 99mTc, the following suggestions to develop nuclear medicine were presented from the viewpoint of a nuclear medicine specialist; development of a brand-new SPECT/CT equipment using semi-conductor, clinical application of new tracers, and reassessment of the existing SPECT studies.
Structural studies of amorphous alloys and hydrogen absorption amorphous alloys by taking advantage of neutron and X-ray diffractions and using the reverse Monte Carlo (RMC) modeling for getting information of the three dimensional atom configuration are reviewed. Voronoi analysis of the RMC models is powerful to elucidate the structural origin of the stability of amorphous state, since Ni-Zr amorphous alloys are unstable in comparison with Cu-Zr ones. The polyhedra around Ni atoms are dominated by trigonal prism-like polyhedra. In contrast, icosahedron-like polyhedra are preferred for Cu. The Ni-Zr amorphous alloys have been reported to stabilize by adding Al. The Voronoi analysis informs us that trigonal prism-like polyhedra decreased in number by adding Al to the Ni-Zr system. On the contrary, the number of icosahedron-like polyhedra was found to increase. The results apparently indicate that the icosahedron-like polyhedra play an important role to stabilize the amorphous state. Moreover, neutron diffraction is a powerful tool to clarify the location of hydrogen atoms in the hydrogen absorption materials. For TbFe2D3.8 and TbNi2D2.4 amorphous alloys, the RMC model structure based on the diffraction data teach us that about 98% of hydrogen atoms occupy tetrahedral sites formed by metal atoms and stabilize the amorphous state.
A diffraction pattern with wide Q-range is obtained by using intense pulsed neutron beam, resulting in the accurate atomic pair distribution function (atomic correlation function, PDF) after Fourier transformation of the diffraction pattern. The atomic pair distribution function can be used for structural analyses of wide range of materials such as amorphous and disordered crystalline materials without periodicity, in addition to the in-between materials. The recent research examples are shown in conjunction with the relationship between the disordered structure and the physical property.