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For new chemical studies on heavy elements, we previously investigated the coprecipitation behaviors with samarium hydroxide for various elements. Herein, we report the coprecipitation experiment using multitracer produced by neutron-induced fission of 235U. The coprecipitation behaviors of 10 elements were investigated: new data were obtained for Sr, Ru, I, Pm, and Np. The present results support the previously obtained conclusion that the hydroxide precipitation properties of various elements can be qualitatively investigated through their coprecipitation behaviors.

The nuclear half-life of 235m U (the first metastable nuclear excited state of 235U) varies depending on chemical environments because the nucleus interacts only with outer-shell electrons in the nuclear internal conversion (IC) process due to its extremely low excitation energy at 76.737 ± 0.018 eV. Elucidating the mechanism of the half-life variation of this unique isomer would largely contribute to understanding interactions between nuclei and shell electrons. For elucidating the mechanism, we aim at measuring both half-lives and IC electron energy spectra of 235m U in various chemical environments. In this study, we developed a retarding-field type magnetic bottle spectrometer for measuring the half-lives and energy spectra with high signal to noise ratio ( S ∕ N ) and high energy resolution. As an evaluation of the fabricated apparatus, the collection efficiency of electrons emitted from a 235m U sample to a channeltron electron detector was measured as a function of the strong and weak magnetic fields and the collection voltage applied to a mesh placed on the entrance of the channeltron detector. Electron collection efficiencies of almost 100% were confirmed under several conditions. Due to this high efficiency together with the low dark noise of the channeltron detector, high S ∕ N measurements have been achieved successfully. An IC-electron energy spectrum of 235m U recorded under the most efficient condition showed an energy resolution ( Δ E ∕ E ) of ∼ 2%, which is sufficiently high to observe small peak shifts and splittings in the IC-electron energy spectra of 235m U compounds. This developed apparatus allows high precision measurements of half-lives and IC-electron energy spectra of 235m U in various chemical environments even with small amount of 235m U and low emission rate of IC electrons.

Kinetic studies were performed on the reactions of phenylboronic acid with L -lactic acid and mandelic acid in acidic aqueous and alkaline solutions in order to specify reactive species in these reactions. It was confirmed that the diprotonated ligand (H 2 L: L -lactic acid or mandelic acid) is less reactive than the monoprotonated ligand (HL − : L -lactate ion or mandelate ion), which made possible direct determination of the rate constants of phenylboronic acid (PhB(OH) 2 ) and its conjugate base, phenylboronate ion (PhB(OH) 3 − ). It was found that PhB(OH) 2 is more reactive than PhB(OH) 3 − . On the basis of kinetic results, it was concluded that the most reactive species are PhB(OH) 2 and HL − at physiological pH 7.4, so the reaction in the boronic acid-based sensor for L -lactate mainly would occur between these species.

Nitrogen-doped ZnO films have been grown by metalorganic vapor-phase epitaxy using diisopropylzinc, tertiary-butanol in the growth temperature range of 300–450 °C. Tertiary-butylamine was used as a nitrogen-dopant source. The nitrogen incorporation and N–H vibrational mode were observed by Raman spectroscopy. The electric properties of the as-grown samples showed n-type with carrier concentration of the order of 1018 cm−3. The N–H vibrational mode was eliminated and high electron concentration was decreased to the order of 1015 cm−3 by post-annealing at 500 °C.