Origin of critical-temperature enhancement of an iron-based high-T_c superconductor, LaFeAsO_{1-x}F_{x} : NMR study under high pressure

Nuclear magnetic resonance (NMR) measurements of an iron (Fe)-based superconductor LaFeAsO_{1-x}F_x (x = 0.08 and 0.14) were performed at ambient pressure and under pressure. The relaxation rate 1/T_1 for the overdoped samples (x = 0.14) shows T-linear behavior just above T_c, and pressure application enhances 1/T_1T similar to the behavior of T_c. This implies that 1/T_1T = constant originates from the Korringa relation, and an increase in the density of states at the Fermi energy D(E_F) leads to the enhancement of T_c. In the underdoped samples (x = 0.08), 1/T_1T measured at ambient pressure also shows T-independent behavior in a wide temperature range above T_c. However, it shows Curie-Weiss-like T dependence at 3.0 GPa accompanied by a small increase in T_c, suggesting that predominant antiferromagnetic fluctuation suppresses development of superconductivity or remarkable enhancement of T_c. The qualitatively different features between underdoped and overdoped samples are systematically explained by a band calculation with hole and electron pockets

Observation of Allende and Antarctic meteorites by monochromatic X-ray CT based on synchrotron radiation

Three-dimensional CT images of the Allende meteorite with a high resolution of 10μm have been obtained nondestructively by a monochromatic X-ray computed tomography (CT) based on synchrotron radiation (SR). The metallic minerals, matrix and chondrules can be clearly observed in the CT images. The CT values, which express the image intensity, allow a quantitative elemental analysis including such as difference in the metallic minerals, i. e., pentlandite and troilite, using the comparison of CT images and elemental images measured by a computer-aided microanalyzer (CMA). The three-dimensional CT images indicate that the metallic minerals surround some chondrules, and the largest chondrule has two humps and well crystallized olivine in its center. These observations suggest that the three-dimensional SR-CT system is a useful method for identification of internal structures of stony meteorites. Additionally, information obtained from the CT images of Antarctic meteorites confirms that the SR-CT system can be applied to classification of stony chondrites

Hydrogen-bond-assisted isotactic-specific radical polymerization of N-vinyl-2-pyrrolidone with tartrate additives in toluene at low temperatures : high-resolution 1H NMR analysis

A diethyl L-tartrate (L-EtTar)-assisted radical polymerization of N-vinyl-2-pyrrolidone has been developed as the first reported example of the synthesis of isotactic-rich poly(N-vinyl-2-pyrrolidone) (PVP). The addition of L-EtTar in toluene at temperatures of –40°C and lower led to a significant increase in the polymer yield by one order of magnitude compared with the reaction in the absence of L-EtTar. Decreasing the polymerization temperature led to increases in the isotacticity of the PVP, with the mm triad reaching 66.4% at −93 °C. 1H NMR measurement at 920 MHz was conducted to establish a reliable strategy for quantifying the triad tacticities. High-temperature NMR measurements at 250 °C were performed using a specially-designed NMR probe, which led to dramatic narrowing of the 1H line width

JASMINE: Near-infrared astrometry and time-series photometry science

The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, the Japan Aerospace Exploration Agency. JASMINE has two main science goals. One is Galactic archaeology with a Galactic Center survey, which aims to reveal the Milky Way’s central core structure and formation history from Gaia-level (∼25 ${\mu}$as) astrometry in the near-infrared (NIR) Hw band (1.0–1.6 ${\mu}$m). The other is an exoplanet survey, which aims to discover transiting Earth-like exoplanets in the habitable zone from NIR time-series photometry of M dwarfs when the Galactic Center is not accessible. We introduce the mission, review many science objectives, and present the instrument concept. JASMINE will be the first dedicated NIR astrometry space mission and provide precise astrometric information on the stars in the Galactic Center, taking advantage of the significantly lower extinction in the NIR. The precise astrometry is obtained by taking many short-exposure images. Hence, the JASMINE Galactic Center survey data will be valuable for studies of exoplanet transits, asteroseismology, variable stars, and microlensing studies, including discovery of (intermediate-mass) black holes. We highlight a swath of such potential science, and also describe synergies with other missions

印刷物・映像情報の電子ファイル化とＷｅｂ上で高速検索可能なシステムの構築(4)

本研究では, 防災研究所に蓄積されてきた研究成果の印刷物・映像情報を電子ファイル化し, Ｗｅｂ上で高速検索可能なシステムの構築を目指している。平成18年度では, 統合型防災情報検索システムの完成度を高め, 職員総覧, OPAC, 機関リポジトリといった, 他のデータベースとも連携できるように構築を行った。また, データの位置情報表記として, GoogleMapsを採用し, データの地理的な表現方法の新しい可能性を示した。At Disaster Prevention Research Institute (DPRI), a large amount of disaster prevention research materials has stored since 1951. The aim of assignment research subject of Division of Technical Affairs is that these base materials are widely exhibited to society, and can be used. In this paper, we show digitization of the materials that is made by the DPRI, and construction of the search engine which can search the disaster prevention research materials on the Internet website at high speed. In last year, we constructed the search engines to search data of the materials published by the DPRI for users efficiently and conveniently on the Internet website. Additionally, the system can search various (not limited to single) information media integrated in media of the format which conformed to an international standard.本研究では, 防災研究所に蓄積されてきた研究成果の印刷物・映像情報を電子ファイル化し, Ｗｅｂ上で高速検索可能なシステムの構築を目指している。平成18年度では, 統合型防災情報検索システムの完成度を高め, 職員総覧, OPAC, 機関リポジトリといった, 他のデータベースとも連携できるように構築を行った。また, データの位置情報表記として, GoogleMapsを採用し, データの地理的な表現方法の新しい可能性を示した。At Disaster Prevention Research Institute (DPRI), a large amount of disaster prevention research materials has stored since 1951. The aim of assignment research subject of Division of Technical Affairs is that these base materials are widely exhibited to society, and can be used. In this paper, we show digitization of the materials that is made by the DPRI, and construction of the search engine which can search the disaster prevention research materials on the Internet website at high speed. In last year, we constructed the search engines to search data of the materials published by the DPRI for users efficiently and conveniently on the Internet website. Additionally, the system can search various (not limited to single) information media integrated in media of the format which conformed to an international standard