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- Author or Editor: H. Nakahara x
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Abstract
An attempt was made to see if there is any correlation between the trace element concentrations in the human blood serum and some specific disease. The serum samples of the patients suffering from cancer, Down syndrome, and Banti syndrome were analyzed by the neutron activation method and compared with the trace element concentrations observed among the clinically healthy men. The cancer patients gave below normal concentrations in Rb, Mn, Fe, Co, Cu, Zn, Al and Se. The Down syndrome patients were found to have similar deficiencies in Cr, Mn, Fe, Co, Zn, Cu and Sb.
Abstract
We made systematic studies of lanthanoid metallofullerenes on the following three properties using the radiochemical method: (1) the relative production yields of metallofullerene species, (2) variation of the HPLC retention time among M(III)@C82 species, and (3) the effects of the reactor irradiation on the survival yields of each metallofullerene species. The production yields of M@C82 relative to La@C82 were found to decrease as the atomic number of M became larger and as the number of atom ratio, M/C, in the carbon rod became larger. On the other hand, the production yields of M1M2@C82, relative to that of LuM@C82 were found to increase for the larger atomic number. The retention time for the M(III)@C82 species in the Buckyprep column was found to become slightly longer for the larger atomic number but it becomes abruptly larger for Gd, and Tb by about 5%. The overall effects of the reactor irradiation on the survival yields (or retention yields) of M@C82 species were found to be (19.7±2.1)%.
Abstract
The primary fragment mass-yield distribution for the asymmetric fission path in heavy nuclei, 233Pa, 239Np, 245Am and 249Bk at the excitation energy of ~20 MeV are experimentally constructed based on the intensities of total kinetic energies for individual mass splits. The results revealed an interesting phenomenon: in all the studied fissioning systems, the inner wings of the mass-yield distributions in the asymmetric fission path appear along the same mass-wall of A = 130 fragment mass. The asymmetric mass-yield distribution indicates the strong effect of structural shells in fragments on the final mass division process of the asymmetric fission path.
Abstract
Chondritic meteorite samples were analyzed nondestructively by photon activation analysis. Powdered samples weighing about 50 mg each were irradiated with photons (
-rays) converted from electrons accelerated by a linear electron accelerator at 20 and 30 MeV. With 30-minute and 6-hour irradiations, 11 and 12 elements with duplication of 6 elements could be determined, respectively. Considering that several major elements including Mg, Si and Fe can be determined in addition to Ti, Rb, Sr, Y and Zr, which cannot or hardly be determined by instrumental neutron activation analysis (INAA) with rather high sensitivity, instrumental photon activation analysis is as effective as INAA.
Abstract
Prompt γ-ray analysis using the internal monostandard method was applied to voluminous archaeological bronze mirrors produced in ancient China. Sn/Cu content ratios were determined nondestructively by this method. Furthermore, Au/Cu, As/Cu, and Sb/Cu content ratios were determined by means of measuring decay γ-rays emitted from radioactive nuclides produced within samples via (n,γ) reactions. It is clear that the Sn/Cu content ratios in bronze mirrors produced in the Sung era is smaller than in ones produced in between the Han and the Tung era.
Abstract
We have, previously, reported on the HPLC elution behavior of the Th, Pa, U, Np, and Am metallofullerenes and the UV/vis/NIR absorption spectra of the Th@C84 and U@C82 species. In this paper, the followings are reported: (1) Pu metallofullerenes were produced and their HPLC elution behavior was investigated using a radiotracer technique. The HPLC chromatogram of this metallofullerene was found to be almost the same as that of the Np and Am metallofullerenes. (2) The oxidation states of Th@C84 and U@C82 produced in macroscopic quantities were examined by XANES (X-ray absorption near edge structure) measurements. The oxidation state of the U atom in the C82 fullerene cage was estimated to be 3+ with the formal charge of the ionic molecule being U3+@C82 3-.
Abstract
Two kinds of scission configurations for certain mass division have been verified by the accurate measurements of fragment velocities in protoninduced fission of actinides: compact and elongated scission configurations. A correlation between the binary scission configurations and mass yield distributions reveals that elongated scission configurations are associated with the symmetric mass distribution and compact scission configurations with the asymmetric mass distribution. The elongation properties of nuclei at scission in a wide range of actinides fissions are studied. The results suggest that the compact and the elongated scission configurations in light actinides fission smoothly change to the scission properties of the symmetric and the asymmetic modes in heavy actinides fission.
Abstract
An internal monostandard method for PGAA is proposed for completely non-destructive analysis of elements in bulky samples by the use of a neutron beam guided out from the reactor. The method is essentially the same as the k
0 method except that it corrects for the change of relative 
-ray counting efficiencies caused by the absorption and scattering of neutrons and absorption of -rays within the sample. Some examples of applications to archaeological samples of earthen wares, bronze mirrors, and to voluminous meteorite samples are demonstrated, and its future application to the in-situ studies of distribution and metabolism of a certain elements in animals is also explained.
Abstract
Time-differential perturbed angular correlation method was applied to Ce@C82 in order to investigate the electronic properties of the encaged Ce atom. The nuclear quadrupole frequency of the nuclear spin of the Ce was successfully determined as ωQ = 6.5(3)·107 rad/s, which is much greater than what has already been estimated for Ce4+ and La3+ in other compounds. By comparing the present value with the values for the Ce4+ and La3+, it was inferred that the valence state of the encaged Ce atom is trivalent.
Abstract
Advantages and uniqueness of radiochemical techniques in fullerene studies are pointed out. Some experimental data are presented on metallofullerenes production yields, HPLC elution behaviors of Y, La, Gd containing fullerenes, encapsulation of a new metal in the carbon cage, stability of the carbon cage against recoil energy, and the distribution of metallofullerenes among various organs of rats.
