Yuanxiang Xie

Effects of Lanthanum on Composition, Crystal Size, and Lattice Structure of Femur Bone Mineral of Wistar Rats

The application of lanthanum (La) in industry, medicine, and agriculture may cause accumulation of the element in human body. This article examines the effects of La on the femur bone mineral of male Wistar rats after administration of La(NO3)3 by gavage at the dose of 2.0 mg La(NO3)3 · kg−1 · day−1 over a 6-month period. Chemical analysis confirmed La accumulation in bone and loss in bone mineral. Thermogravimetric analysis showed a decrease in the mineral-to-matrix ratio and an increase in carbonate content. Fourier-transform infrared spectrometry revealed elevation in the contents of labile carbonate and acidic phosphate. The synchrotron radiation small-angle X-ray scattering study presented a smaller mean thickness of the mineral crystals in the bone of La-treated rats. The synchrotron radiation-extended X-ray absorption fine structure analysis indicated that the La treatment resulted in a lowered disorder in the crystals. The smaller size, more adsorbed labile carbonate, and more acidic phosphate made the bone mineral easier to dissolve, as revealed in the kinetic measurement of bone demineralization. These findings suggest that La retards bone maturation of rats.

Newβ-delayed proton precursor135Gd

Unknownβ-delayed proton precursor135Gd has been synthesized by the reaction106Cd (32S, 3n) and identified using a helium-jet recoil fast tape-transport system with aγ(X)-p coincidence measurements. Itsβ-delayed proton spectrum has been observed. The half-life of135Gd decay has been determined to be 1.1±0.2 s.

Neaw β-delayed proton precursor121Ce near the proton drip-line

Unknown β-delayed proton precursor121Ce was produced via the reaction of92Mo(32S, 3n), and identified by an He-jet fast tape transport system with “P-γ” coincidence measurements. The half-life of121Ce decay was determined to be (1.1 ± 0. l)s. Its energy spectrum of β-delayed protons was measured and the β-delayed proton branching ratio for121decay was roughly estimated to be ∼ 1 %. After β-delayed proton decay of the precursors119Ba,121Ba and122La, some of γ-transitions from low-lying states to the ground states in their “daughters” were observed for the first time.

β-delayed proton decays near the proton drip line

We briefly reviewed the experimental study on β-delayed proton decays near the proton drip line published by our group during the period of 1996–2004, namely the first observation of the β-delayed proton decays of 9 new nuclides in the rare-earth region and the new measurements of β-delayed proton decays of 5 nuclides in the mass ∼90 region near theN=Z line with the aid of the “p-y” coincidence in combination with a He-jet tape transport system. In the meantime some important experimental technique details were supplemented. The experimental results, including the half-lives, spins, parities, deformations and production reaction cross sections for the 14 nuclei were summarized and compared with the current nuclear-model predictions, and then the following points were represented. (1) The experimental half-lives for85Mo and92Rh as well as the predicted “waiting point” nuclei89Ru and93Pd are 5–10 times longer than the theoretical predictions given by Möller et al. using a macroscopic-microscopic model. It considerably influences the predictions of the abundances of the nuclides produced in the rp-process. (2) The current-model predictions are not consistent with the experimental assignments of the spins and parities for the proton drip-line nuclei142Ho and128Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods-Saxon-Strutinsky method reproduced the experimental results. (3) The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately.