Yohtaro Matsuo

Tokyo Institute of Technology

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Kouichi Yasuda

Tokyo Institute of Technology

Shiushichi KIMURA

Tokyo Institute of Technology

Tadashi Shiota

Okayama University

Katsuhisa Jinbo

Tokyo Institute of Technology

Junichi Tatami

Yokohama National University

Tatsuya Shiogai

Sumitomo Osaka Cement (Japan)

Noboru Miyata

Comprehensive Research Organization for Science and Society

K Iwahashi

Azabu University

Ryoichi Furushima

National Institute of Advanced Industrial Science and Technology

Fumio NAGAI

Corning (United States)

Cooperative Institutions

Tokyo Institute of Technology

Osaka University

Kyoto University

Kyushu University

The University of Tokyo

Tohoku University

American Ceramic Society

University of Tsukuba

Tokyo University of Science

National Institute of Advanced Industrial Science and Technology

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Mechanical Properties of Carbon Fiber-Reinforced hBN Matrix Composites at Elevated Temperature

Key engineering materials (1998)

Yohtaro Matsuo Shogo Kumagai Kazuhiro Yasuda

Matrix (chemical analysis)

10.4028/www.scientific.net/kem.164-165.137

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Citations (3)

Reexamination of diversifying selection of polymorphic allozyme genes by using population cages in Drosophila melanogaster

Proceedings of the National Academy of Sciences (1983)

Tsuneyuki Yamazaki Shinichi Kusakabe Hidenori Tachida M. Ichinose Hiroshi Yoshimaru

Several investigators have reported increased heterozygosity for allozyme markers in laboratory experiments simulating a variable environment and have concluded that there is diversifying selection for allozyme variants. We found no change in heterozygosity in 28 large population cages where temperature, food, and light were each set at three levels, two constant and one variable, in a factorial design. Specifically, there was no change in heterozygosity when 0, 1, 2, or 3 factors were variable. The discrepancy between our negative results and earlier positive ones is that our experiments were started from a large caged population of flies which had been maintained for 6 years—long enough to be very near to linkage equilibrium. We suggest that the earlier results may have been the result of linkage between neutral, or nearly neutral, allozyme markers and selected loci or in some cases, inversions.

Linkage (software)

10.1073/pnas.80.18.5789

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Citations (26)

Nucleotide variation and divergence in the histone multigene family in Drosophila melanogaster.

Genetics (1989)

Yohtaro Matsuo Taisuke Yamazaki

Abstract Nucleotide differences in the histone H3 gene family in Drosophila melanogaster were studied on three levels: (1) within a chromosome, (2) within a population and (3) between species (D. melanogaster and Drosophila simulans). The average difference within the H3 gene within a chromosome was 0.0040 per nucleotide site, about 52% of that within a population (0.0077). The proportion of divergent sites between the two species was 0.0575, which is about 8.5 times the difference within a species. The distribution of divergence between species was similar to that of variation within a species. Divergence and variation were noted to be greatest in the 3' noncoding region and least in the coding region. Values intermediate between these were found for the 5' noncoding region. Divergence and variation in silent sites exceeded those in the total coding region, thus indicating possible purifying selection for amino-acid-altering change. Phylogenetic relations among H3 genes and genetic differences on these three levels are evidence for the concerted evolution of the histone gene family. The molecular mechanism by which variation is produced and maintained is discussed.

Melanogaster

Nucleotide diversity

Molecular evolution

Concerted evolution

Coding region

10.1093/genetics/122.1.87

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Citations (51)

A Trend of the Industrial Standards for the Environment and the Development of the Environmental Science

Refractories and Industrial Ceramics (2003)

Yohtaro Matsuo

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Damage Evaluation of Brittle Materials Subjected to Thermal and Mechanical Stresses Using Ultrasonic Pulse-echo Method

Kikai Zairyou, Zairyou Kakou Gijutsu Kouenkai kouen rombunshuu/Kikai Zairyo, Zairyo Kako Gijutsu Koenkai koen ronbunshu (2003)

Yohtaro Matsuo Takuma Okajima Tadashi Shiota Kouichi Yasuda

The damages of brittle materials (alumina-carbon refractories) subjected to compressive stress or thermal shock were evaluated using ultrasonic pulse-echo method. The changes of the wave propagation velocities obtained from the base-reflected echo were in good correspondence with the damage processes of the used materials under uniaxial compression test. It was found that the intensity of the peak frequency of the back-scattered waves analyzed by FFT decreased as the damage progressed. In compression test, damages occurred even in unloading process. In the specimen damaged by thermal shock, the greater the equivalent normal stress became, the greater the damage did in tensile stress region. It was found that even in compressive region, damage was observed to some extent.

Brittleness

Thermal shock

10.1299/jsmemp.2003.11.161

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The Influence of Grain Size and Secondary Phase on the Fracture Toughness of Sintered MgO Bodies (Part 2)

Journal of the Ceramic Society of Japan (1993)

Yasuhiko TSURU Kouichi Yasuda Yohtaro Matsuo Shiushichi KIMURA Eiichi Yasuda

The influence of grain size and secondary phase on the fracture toughness (KIC) of sintered MgO bodies was investigated. Sintered MgO bodies doped with 1-10wt% Fe2O3 were made by hot-pressing. The grain size was changed by annealing. The fracture toughness (KIC) was measured by a chevron-notched beam method. The fracture toughness of sintered MgO bodies doped with Fe2O3 was independent of the grain size. However, it increased with the increase of the amount of Fe2O3, and reached 2.5MPa√m at the sintered MgO body doped with 10wt% Fe2O3, which is 50% larger than that of pure MgO. The fractography revealed that the toughening of Fe2O3-doped MgO bodies corresponded to the increase in the fraction of stepwise transgranular fracture on the fracture surfaces. It was considered that the change in fracture mode resulted from residual thermal stresses generated around MgFe2O4 precipitates.

Transgranular fracture

Fractography

10.2109/jcersj.101.169

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Citations (1)

1444 Influence of the flaw-size distribution's parameter on the fracture strength in ceramics

The proceedings of the JSME annual meeting (2008)

Chisato Wakabayashi Yohtaro Matsuo Kouichi Yasuda Tadashi Shiota

In this report, gamma distribution is used for flaw size distribution, and their parameters are estimated by the most likelihood method by using the flaw size data reported by Nakamura et.al. Taking the logarithms of its probability density function, a term in proportion to the flaw size is several orders of magnitude larger than the other terms. Therefore, linearization of flaw size distribution can be made by neglecting the other terms. To compare the experimental data, the gamma distribution parameters are used for the linearization, so this parameter expresses the character of flaw size distribution well. To consider about the relation between the fracture strength and flaw size distribution, the fracture strength and the shape parameter of gamma distribution are discussed.

Linearization

10.1299/jsmemecjo.2008.1.0_295

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[Association between alcoholics and the genotypes of ALDH2, ADH2, ADH3 as well as P-4502E1].

PubMed (1995)

Kazuhiko Nakamura Hiroshi Suwaki Yohtaro Matsuo Yoshiyuki Ichikawa Ryosuke Miyatake

We examined the genotypes of ALDH2, ADH2, ADH3 and P-4502E1 loci of alcoholics and nonalcoholics. Also we compared the frequencies of the homozygous ALDH2*1/1 genotype and heterozygous ALDH2*1/2 genotypes in alcoholics. Our study reported differences in the allelic frequencies of ALDH2, ADH2 and ADH3 loci between alcoholics and nonalcoholics. For alcoholics, it was indicated that ADH2 and ADH3 plays an important role for alcoholism. For genotypes of P-4502E1, no significant difference was observed between alcoholics and nonalcoholics. Alcoholics with the heterozygous ALDH2*1/2 genotype had significantly higher frequency of the ADH2*1 than that of alcoholics with ALDH2*1/1 genotype. Concerning the alcoholics with the heterozygous ALDH2*1/2 genotype, we assumed that ADH2*1 plays a role for the development of alcoholism.

ALDH2

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Citations (14)

Forming of Ceramic Powders by Cyclic-CIP

Journal of the Ceramic Society of Japan (1990)

Toshiyuki Nishimura Katsuhisa Jinbo Yohtaro Matsuo Shiushichi KIMURA

The effect of the bias pressure of Cyclic-CIP. on the bulk density of alumina compact was examined, and the following results were obtained.(1) When the maximum pressure is constant, the high bulk density can be obtained with decreasing bias pressure.(2) Relative bulk density of 74.2% was obtained under the condition of 100MPa in maximum pressure, 0MPa in bias pressure and 10000 cycles.(3) In order to obtain the same bulk density, the maximum pressure of C-CIP can be decreased over one-tenth of that of static-CIP.

Relative density

Maximum density

Ambient pressure

10.2109/jcersj.98.735

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Citations (10)

Derivation of the distribution function of fracture location in a non-linear elastic body with multiple fracture origins and its application.

Journal of the Society of Materials Science Japan (1990)

Kouichi Yasuda Yohtaro Matsuo Shiushichi KIMURA

A recently established statistical theory of fracture location combined with a competing risk theory was used to derive the distribution functions of fracture location, defect size and defect orientation. In this report, a new theory was applied to non-linear elastic bodies obeying a non-symmetric constitutive equation. Practically, a square cross-sectioned beam loaded on a three point bending apparatus was analyzed to study three types of competing defects; inner defects, surface defects, edge defects as fracture origins. From these results, the effect of non-linearity of the constitutive equation on the distribution function of fracture location was discussed, and a new estimating method of the constitutive equation derived from fracture location data was suggested.

10.2472/jsms.39.138

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