Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: K. Murata x
  • All content x
Clear All Modify Search

Abstract  

We have developed a system to measure electrical resistivity, thermopower and thermal conductivity of tiny fragile organic conductors simultaneously. Figure of merit Z has been successfully determined from these transport coefficients for a two-dimensional organic conductor τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y, (y≤0.875), where EDO-S,S-DMEDT-TTF is ethylenedioxy-S,S-dimethylethylenedithio-tetrathiafulvalene, for the first time.

Restricted access

Abstract  

An analytical method was developed for the measurement of low-level 54Mn in soil sample by ultra low-background g-ray spectrometry after radiochemical separation. The method consists of decomposition of sample by a mixture of HNO3 and HF, dissolution by HNO3, precipitation as hydroxide, solvent extraction with diisopropyl ether and anion exchange. Finally, for purification of Mn it was precipitated as MnO2 by adding KClO3. 54Mn in the precipitate was measured by ultra low-background well-type Ge detector at Ogoya Underground Laboratory. Measurements of 54Mn using 30-200 g of soil samples from the JCO grounds were successfully performed by the present method. The minimum detectable activity of 54Mn was about 0.01 dpm (0.2 mBq) for a 7-day counting period.

Restricted access

Abstract  

To estimate fast neutron fluence released by the JCO criticality accident in Tokai-mura, 54Mn, which is produced by the 54Fe(n,p)54Mn reaction, was determined in soil samples by ultra low background g-ray spectrometry after radiochemical separation. Activities of 54Mn, using 30-200 g soil samples were detected in soil samples from 13 points in all directions within a 20 m zone from the precipitation vessel we have used. The levels of 54Mn ranged from 0.015 to 2.12 mBq/g soil. By using these data and MCNP, the fast neutron fluences were estimated.

Restricted access

Purpose: Human hands are excellent in performing sensory and motor function. We have hypothesized that blood flow of the hand is dynamically regulated by sympathetic outflow during concentrated finger perception. To identify this hypothesis, we measured radial blood flow (RBF), radial vascular conductance (RVC), heart rate (HR), and arterial blood pressure (AP) during Braille reading performed under the blind condition in nine healthy subjects. The subjects were instructed to read a flat plate with raised letters (Braille reading) for 30 s by the forefinger, and to touch a blank plate as control for the Braille discrimination procedure. Results: HR and AP slightly increased during Braille reading but remained unchanged during the touching of the blank plate. RBF and RVC were reduced during the Braille character discrimination task (decreased by −46% and −49%, respectively). Furthermore, the changes in RBF and RVC were much greater during the Braille character discrimination task than during the touching of the blank plate (decreased by −20% and −20%, respectively). Conclusions: These results have suggested that the distribution of blood flow to the hand is modulated via sympathetic nerve activity during concentrated finger perception.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Komura, K. Komura, Y. Kuwahara, Y. Kuwahara, T. Abe, T. Abe, K. Tanaka, K. Tanaka, Y. Murata, Y. Murata, M. Inoue, and M. Inoue

Summary  

Extremely low activity levels of cosmic ray induced nuclides have been measured in freshly precipitated rainwater by quick chemical separation coupled with ultra low background gamma-spectrometry. The nuclides detected were 38S (T 1/2 = 2.83 h)-38Cl (37.2 m), 39Cl (55.6 m), 24Na (14.96 h), 28Mg (20.9 h), 7Be (53.3 d) and 22Na (2.602 y). The number of atoms in rain water were evaluated to be ranging from 400-1900 l-1 for 39Cl (n = 6, mean: 1200), 30-1500 l-1 for 24Na (n = 16, mean: 520), 80-600 l-1   for 28Mg (n = 13, mean: 260), 1 . 106-4 . 107 l-1 for   7Be (n = 16, mean: 7 . 106) and 2 . 103-1 . 105 l-1 for 22Na (n = 9, mean: 2 . 104). Measurements of activity levels and activity ratios of short-lived cosmic-ray induced short-lived nuclides will open new method to understand atmospheric processes occurred at the altitude of rain cloud.

Restricted access

Abstract  

The effect of thermal treatment on the electrical conductivity was studied for a quasi-one-dimensional organic conductor, (DIMET)2I3 (DIMET=dimethyl(ethylenedithio)tetrathiafulvalene). After heating the samples up to a temperature between 340 and 370 K, the electric resistivity was measured at low temperature down to 2 K and under pressure up to 1.6 Gpa. (DIMET)2I3 shows irreversible decrease in the electric resistivity between 350 and 356 K on heating. It was found that the heating above 350 K suppresses the spin-density-wave transition at 40 K and another metal-insulator transition appears at 18 K.

Restricted access
Acta Biologica Hungarica
Authors: Kanako Aono, A. Fusada, Y. Fusada, W. Ishii, Y. Kanaya, Mami Komuro, Kanae Matsui, S. Meguro, Ayumi Miyamae, Yurie Miyamae, Aya Murata, Shizuka Narita, Hiroe Nozaka, Wakana Saito, Ayumi Watanabe, Kaori Nishikata, A. Kanazawa, Y. Fujito, R. Okada, K. Lukowiak, and E. Ito

The pond snail, Lymnaea stagnalis , can locomote on its back utilizing the surface tension of the water. We have called this form of movement ‘back-swimming’. In order to perform this behavior, the snail must flip itself over on its back so that its foot is visible from above. Little is known about the mechanism of this back-swimming. As a first step for the elucidation of this mechanism, we measured the speed of back-swimming of Lymnaea at the different times of the day. They back-swam significantly faster in the morning than just before dark. These data are consistent with our earlier findings on circadian-timed activity pattern in Lymnaea. Lymnaea appear to secrete a thin membrane-like substance from their foot that may allow them to back-swim. To confirm the existence of this substance and to examine whether this substance is hydrophobic or hydrophilic, we applied a detergent onto the foot during back-swimming. A single drop of 1% Tween 20 drifted Lymnaea away that were still kept at the water surface. These results suggest that Lymnaea secrete a hydrophobic substance from their foot that floats to the water surface allowing Lymnaea to back-swim.

Restricted access