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As a new damping material, the authors first developed a Zn-22wt.%-Al eutectoid alloy with ultra-fine grains exhibiting superplasticity at room temperature by means of thermomechanical controlling processes (TMCPs). The Zn-Al alloy has a few advantages such as low work-hardening rate and high ductility over a conventional seismic damping material, for instance, a low-yield-point steel. In addition, Zn-Al alloys are environment-conscious because of no harmful metal like Pb. However, when Zn-Al alloys are subjected to plastic deformation, since its work hardening is small, plastic deformation proceeds locally so that required absorption energy cannot be sufficiently obtained, and local fracture and local deformation instability can take place easily, which is the intrinsic characteristic of superplastic materials. Therefore we attempted to develop a shear panel type, a brace type damper for tall buildings and a bending type damper for Japanese wooden houses using FEM analysis in order to minimize localized strain and local deformation and to determine the optimum shape for this Zn-Al superplastic seismic damper. As a result, an ecological and high-energy absorption seismic dampers, so-called “maintenance-free seismic damper,” was successfully developed.

To allow adoption of serum pepsinogen as a screening indicator of gastric cancer, serum pepsinogen I & II levels, the ratios of PG I / PG II and the serum gastrin levels in a general population were studied using 850 samples selected at random from a rural area in Japan. The collected data were analyzed statistically to determine the distribution characteristics by various categories of sex and age. The following results were obtained: 1. The distributions of PG I and PG II, the ratios of PG I/PG II and serum gastrin values largely deviated from the normal distribution. Therefore, the use of non-parametrical methods was recommended for analysis of these data. 2. Although no significant difference between all selected men and all selected women was observed in any of the three parameters of PG I and PG II levels and the ratios of PG I / PG II, a significant difference between men and women was observed for PG I levels in under-fifty age groups. On the other hand, the median serum gastrin value (92.0 pg/ml) in all selected men was significantly lower than that (101.0 pg/ml) in all selected women. A statistically significant difference between men and women was observed in serum gastrin levels both in the under-forty age group and in the sixty and over age group. 3. No significant difference was observed in the pattern of changes in PG I levels with increasing age in either men or women. While PG II levels in men varied irregularly with advancing age, PG II levels in women showed obvious increases with advancing age. The ratios of PG I / PG II showed a tendency to decrease with advancing age in both men and women. Conversely, serum gastrin levels increased with advancing age in both men and women.

Natural gas hydrate, existing in marine sediments worldwide and in permafrost regions, is anticipated to be a promising energy resource. It is essential to consider the mechanical properties, including their time dependence, of a gas hydrate reservoir to simulate the geomechanical response to gas extraction from a reservoir. Recently it has been revealed that gas-hydrate-bearing sediments have rocklike mechanical characteristics due to the cementation effect of the hydrate between soil particles. To obtain information about the time dependence of gas-hydrate-bearing sediments, experimental methods for drained triaxial compression tests including a procedure for the preparation of artificial methane-hydrate-bearing sediment specimens have been established. Using these methods, constant-strain-rate tests and creep tests on artificial methane-hydrate-bearing sediment specimens have been conducted. In this report, the methods and results of the tests are presented, and the time-dependent behaviors of methane-hydrate-bearing sediment are discussed. On the basis of the results, the strain-rate dependence of the peak strength was examined, and it was found that the time dependence of the artificial methane-hydrate-bearing sediment is as strong as that of frozen sand and stronger than that of many other geological materials. It was also found that the creep deformation of methane-hydrate-bearing sediment is much larger than that of water-saturated sand without the hydrate. The experimental data presented in this report are expected to be used to obtain a full understanding of the deformation mechanism of methane-hydrate-bearing sediments and to formulate a constitutive equation for methane-hydrate-bearing sediments in future studies.

2006年度～2008年度科学研究費補助金（基盤研究(Ｂ)）研究成果報告書, 研究概要：ドミニカ共和国（ド国）、タンザニア、中国で上部消化管疾患に関する健康調査を実施し、ヘリコバクター・ピロリ（H. pylori）感染および慢性萎縮性胃炎(CAG)に関与すると考えられる因子の疫学的検討を行った。すなわち、性・年齢、人種・民族、食習慣・食生活を含めた生活習慣、生活環境、並びに上部消化管疾患関連症状や既往歴、などがH. pylori感染およびCAGの罹患、並びにH. pylori菌の病原性に関与するCagA抗体保有の有無に及ぼす影響について検討した。

In order to evaluate a methane gas productivity of methane hydrate reservoirs, it is necessary to develop a numeric simulator predicting gas production behavior. For precise assessment of long-term gas productivity, it is important to develop a mathematical model which describes mechanical behaviors of methane hydrate reservoirs in consideration of their time-dependent properties and to introduce it into the numeric simulator. In this study, based on previous experimental results of triaxial compression tests of Toyoura sand containing synthetic methane hydrate, stress-strain relationships were formulated by variable-compliance-type constitutive model. The suggested model takes into account the time-dependent property obtained from laboratory investigation that time dependency of methane hydrate bearing sediment is influenced by methane hydrate saturation and effective confining pressure. Validity of the suggested model should be verified by other laboratory experiments on time-dependent behaviors of methane hydrate bearing sediment.