Wataru Sato

Nondestructive Determination of Major Elements in a Large Sample by Prompt γ Ray Neutron Activation Analysis.

An internal monostandard method is proposed for the nondestructive determination of major elements in large samples by prompt γ ray neutron activation analysis. It successfully overcomes the problems characteristic of large samples, such as the absorption and scattering of incident neutrons and the absorption of emitted γ rays. In order to make this proposed method understood theoretically, an equation is presented and its validity for the analysis of large samples discussed. In principle, the proposed method gives relative contents in large solid samples, whereas it allows absolute determination for samples in solution form. As a demonstration for the analysis of a large solid sample, we analyzed an earthen vessel, and the major elements in the sample (Na, Mg, Al, Si, K, Ca, Ti, Mn, and Fe) were determined within the uncertainty of 10%, except for Mn. This method was also tested for samples in solution form, and it was found that the absolute content of a target element could be obtained by constructing a calibration curve using several known standard solutions of different concentrations. Residual radioactivity after irradiation was also examined and found to be so little that the sample could be taken outside the radiation-controlled area within a few days after the irradiation.

New Lanthanoid Metallofullerenes and their HPLC Elution Behavior

Abstract HPLC behaviors of metallofullerenes of 14 lanthanoid elements were studied by use of radiotracers, and the species of some of the metallofullerenes were identified by mass spectroscopy. From the HPLC elution behaviors, 14 lanthanoid elements forming metallofullerenes were found to be grouped into two, namely, Sm, Eu, Tm and Yb as one group and the rest of the elements as another. Some new species of metallofullerenes like La@C74, and M@Cn (M=Eu, Tm, Yb; n=74, 82, 84, 88, 90, 92, 94) have been identified. The observed retention times of metallofullerenes are discussed in terms of the number of carbon atoms of the cage and from consideration of the electron donor and acceptor relation between the fullerene species and the HPLC stationary phases.

Analysis of archaeological samples by the internal monostandard method of PGAA

Nondestructive determination of major and trace elements within voluminous materials has been demonstrated by prompt γ-ray neutron activation analysis. Some fragmented pieces of pottery bowls considered to have been produced in the late 18th century were analyzed by a new internal monostandard method, and noticeable differences of the elemental contents and significant correlations of the elemental distributions were observed among the samples. The possibility of identification of producing areas of unearthened material is demonstrated by the analytical results and the applicability of this method to the investigation of precious samples in a completely nondestructive way is verified in practice.

Some Basic Studies on Non-Destructive Elemental Analysis of Bulky Samples by PGAA

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 k0 method except that it corrects for the change of relative γ-ray counting efficiencies caused by the absorption and scattering of neutrons and absorption of γ-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.

Nuclear Reactions and Radionuclides in the Study of Fullerenes

Radiochemical techniques have been applied in various ways to the study of fullerenes and metallofullerenes for the past several years, and they have provided invaluable information pertaining to the stability, structures, and formation of the novel carbon material. This paper reviews those experimental results that have fully shown the usefulness and uniqueness of radionuclides demonstrated in the field of fullerene science.

Robot design support system based on interactive evolutionary computation using Boltzmann selection

Recently, the need of users is changing to the efficient quality of functions with the sophisticated design and reasonable price. Furthermore, current users prefer to the personal customization of products. Accordingly, a design support system is useful and helpful for non-expert people to design products easily, but such non-expert people might take much time and load in the product design. Therefore, we proposed interactive design support system based on evolutionary computation, and applied the proposed method to the design of robot partners. However, it is very difficult to reflect human evaluation to the generation of the next design candidates. Therefore, we propose an estimation method of human evaluation using fuzzy inference in the interactive design support using the evolutionary computation. Furthermore, we use iPhone simulator to evaluate the human impression based on direct interaction with the designed robot partner. Finally, we discuss the effectiveness of the proposed system through several simulation and experimental results.

Interactive evolutionary computation for robot design support system

Recently, human-friendly support systems for product design have been developed as demands of individual user to products become diversified. In the previous works, Interactive Evolutionary Computation has been applied to support product designs. An advantage of Interactive Evolutionary Computation is that it can perform the optimization based on human preference and feeling in addition to the evaluation by fitness functions. However, the main target of the application of Interactive Evolutionary Computation lies in the design of appearance, not functionality. The simultaneous optimization of appearance and functions of a target product is very important to shorten the cycle of product development. Therefore, in this study, the final aim is to develop a support system for simultaneous design of appearance, shape, and functionality. First of all, in this paper, we focus on the development of a design system based on the users preference. We apply Interactive Evolutionary Computation to make designs based on the human preference and feeling. As an example, we apply a proposed method to design a partner robot because the systematic tools of developing robots for daily use have rarely been developed. This system aims not to make final design but to make “Relation between the user and the robot.” Next, we focus on the development of a simulation system to confirm the results of the developed. We can see images of the robot and movements, etc. by using this system, even if we do not actually make robots. Finally, we discuss the effectiveness of the proposed methods and future works.

Electronic state of Ce@C82

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.

Dynamic Motion of Ce@C80 —Comparison Study with Ce@C82—

Characterizable amount of La@C80 was prepared by means of a two-stage HPLC purification of fullerene ingredients which were extracted from carbon soot in macroscopic quantity. In the same way as the investigation of Ce@C82 and CeLa@C80 in our previous work, molecular dynamic behavior of the newly purified species has been studied by means of time-differential perturbed angular correlation measurements. The data analyzed have shown that powder Ce@C80 has somewhat slow rotational motion at room temperature compared with Ce@C82 of the same form and the electric field gradient at the encaged Ce nucleus is almost equal to that at the corresponding atom of Ce@C82.