Search results

1

Positron Annihilation in Carbon Nanotubes Studied by Coincidence Doppler Broadening Spectroscopy

100%

Murakami H., Sato K., Kanazawa I., Sano M.

Acta Physica Polonica A

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2008

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vol. 113

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issue 5

1479-1484

EN

In order to assign the sites of positron annihilation, coincidence Doppler broadening spectra were measured for a highly oriented pyrolytic graphite crystal, graphite powder, multi-walled carbon nanotubes (MNTs) and cup-stacked carbon nanotubes (CNTs). The spectrum for graphite powder normalized to that for highly oriented pyrolytic graphite (HOPG) is almost flat in the momentum region from 7×10^{-3} to 13×10^{-3} m_{e}c, having a ratio close to unity. The flat spectrum demonstrates that positrons injected into graphite powder annihilate in the interlayer spaces of piled graphite sheets, in the same manner as positrons in highly oriented pyrolytic graphite annihilate in the bulk. The coincidence Doppler broadening spectra for MNTs and CNTs are quite different from that for highly oriented pyrolytic graphite, which indicates that positrons injected into MNTs and CYTs annihilate not in the bulk, but on surface. The positron lifetime spectrum for multi-walled carbon nanotubes is analyzed in terms of a single component due to surface-trapped positrons, while that for CNTs is decomposed into three components attributable to para-positronium surface-trapped positrons and ortho-positronium. The difference between the coincidence Doppler broadening spectrum for CNTs and that for MNTs is explained in terms of positron annihilation on zigzag surfaces of CNTs which are composed of both graphite-sheet and graphite-edge planes.

2

Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

88%

Sato K., Murakami H., Ito K., Hirata K., Kobayashi Y.

Acta Physica Polonica A

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2008

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vol. 113

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issue 5

1511-1516

EN

Positron (e⁺) and positronium (Ps) annihilation processes in polymers are studied by positron age-momentum correlation spectroscopy, which can sensitively probe momentum distributions of e⁺, p-Ps, and o-Ps. For polyether sulfone and ethylene tetrafluoroethylene copolymer belonging to oxygen-containing polymers (O group) and fluorine-containing polymers (F group), respectively, significant effects of positron trapping by polar element are observed. The Doppler profile of o-Ps pick-off annihilation is strongly influenced by F atoms, giving rise to anomalous broadening. The results are discussed together with our previous data of the S-I₃ correlation in order to explore the feasibility of chemical analysis around the free volumes by age-momentum correlation spectroscopy.

3

Body weight of high and low aggression mice under various population densities

88%

Oikawa T., Kawamoto Y., Nakamura S., Morimasa T., Sato K.

Journal of Applied Genetics

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2000

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vol. 41

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issue 1

35-42

EN

The body weight of 21st generation mice selected divergently according to their aggression was compared in different population densities. The mice under isolated housing demonstrated higher levels of aggression in both lines. The growth of the mice was similar among the groups of different population densities in both lines. Only the males of the high aggression line showed a large phenotypic variance in the medium and high population densities, whereas no differences were observed among the population densities in males of the low aggression line or in the females of both lines. Our study suggested that the aggression of males was a source of extra variance in the high population density, resulting in heterogeneity of variance and genotype by sex interaction.

4

Detection of Shallow Dislocations on 4H-SiC Substrate by Etching Method

64%

Ishikawa Y., Yao Y., Sato K., Sugawara Y., Danno K., Suzuki H., Bessho T., Kawai Y., Shibata N.

Acta Physica Polonica A

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2011

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vol. 120

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issue 6A

A-25-A-27

EN

Correlation between dislocation types in epitaxial 4H-SiC and etch pit types on the 4H-SiC wafer surface were investigated by etch pit method and transmission electron microscope. Shallow dislocation on the wafer was found to form round pit without core. The shallow dislocation was estimated half-loop type in wafer and this estimation explains that step-flow growth converts half-loop dislocation into complex dislocation composed by threading dislocation and basal plane dislocation.

5

The utility of patent ductus arteriosus closure with hemostatic clip in dogs

55%

Takeuchi A., Uemura A., Goya S., Shimada K., Yoshida T., Hara S., Sato K., Shiraishi K., Yairo A., Kto K., Matsuura K., Takeuchi A., Uemura A., Goya S., Shimada K., Yoshida T., Hara S., Sato K., Shiraishi K., Yairo A., Kto K., Matsuura K.

Polish Journal of Veterinary Sciences

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2020

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vol. 23

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issue 2

Refine search results

Positron Annihilation in Carbon Nanotubes Studied by Coincidence Doppler Broadening Spectroscopy

Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

Body weight of high and low aggression mice under various population densities

Detection of Shallow Dislocations on 4H-SiC Substrate by Etching Method

The utility of patent ductus arteriosus closure with hemostatic clip in dogs