Kobayashi Institute of Physical Research

Japan

Kobayashi Institute of Physical Research

Japan
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Kunimatsu S.,Japan Advanced Institute of Science and Technology | Kitamura Y.,Kobe University | Hirao Y.,Kobayashi Institute of Physical Research | Ohta K.,OYO Seismic Instrumentation Corporation
Recent Advances in Environmental Vibration - Proceedings of 6th International Symposium on Environmental Vibration, ISEV 2013 | Year: 2013

Since it is supposed that environmental vibrations in a house are influenced by the house; structure, the foundation structure of house and the ground where a house is built, it is important to grasp the vibration transfer characteristics from the ground near a residential house to the house in-side by using a reproducible exciting method not the general vibration source such as the road traffic. This paper deals with the development of an exciting system for examination of environmental vibration and its application to measurement of vibration in several houses.


Ishii H.,Tokyo University of Science | Nakajima T.,Tohoku University | Furukawa T.,Kobayashi Institute of Physical Research | Okamura S.,Tokyo University of Science
Japanese Journal of Applied Physics | Year: 2013

The polarization switching times of vinylidene fluoride (VDF)/trifluoroethylene (TrFE) copolymer thin films with a thickness of 40nm were measured at temperatures ranging from -50 to 50 °C and applied fields ranging from 75 to 600 MV/m. The switching time was drastically reduced by increasing the applied field at all temperatures. The relationship between the switching time and the reciprocal applied field obeyed the exponential law in the low-field region and the power law in the high-field region. The threshold field between the exponential law and the power law became monotonically lower with decreasing temperature. Furthermore, the exponent value in the power law increased with decreasing temperature. This seems to be caused by a change in domain growth from two-dimensional-like to three-dimensional-like or in nucleation mechanism with decreasing temperature. © 2013 The Japan Society of Applied Physics.


Hirai N.,University of Shizuoka | Sobue N.,University of Shizuoka | Date M.,Kobayashi Institute of Physical Research
Journal of Wood Science | Year: 2011

This article reports the piezoelectric moduli of wood d31, d32, and d36. The piezoelectric moduli of wood d31 and d32 have not been previously reported, although there has been much research on the d14 and d25 moduli of wood. The moduli d31, d32, and d36 were measured carefully because their absolute values were considerably smaller than those of d14 and d25. For Softwoods, d36 values were mostly negative, whereas the values for hardwoods had either positive or negative values. The other moduli, d31 and d32, were a mixture of positive and negative values in softwoods and hardwoods. The existence of d31 and d32 suggests the presence of an electrical polarity of the cellulose crystal in the fiber direction of the wood. The polarities of d31 and d32 became clear from wood in the outer part of the trunk, where the crystallinity of cellulose is large and the alignment of the crystals becomes parallel to the fiber direction. © 2010 The Japan Wood Research Society.


Hamashima H.,Kumamoto Industrial Research Institute | Hokamoto K.,Kumamoto University | Yamashita M.,Gifu University | Sato Y.,Dr. Y. Satos Office | Furukawa T.,Kobayashi Institute of Physical Research
Materials Science Forum | Year: 2011

Stress-strain relationships of polycarbonate (PC) were determined over a very wide range of strain rates including shock wave regime. High-velocity plate impact tests, drop-weight tests, and quasi-static tests using universal and Instron testing machines were used for the high strain rate (107 s-1), medium strain rate (102 s-1) and low strain rate (10-4 s-1) tests, respectively. The revised unsteady wave sensing system (UWSS) for plate impact tests was newly developed to determine the stress-strain relationships and Hugoniot linear relation of PC. The system consists of a powder gun for plate impact tests and three polyvenylidene fluoride (PVDF) gauges embedded in the PC utilizing a newly developed nanosecond UWSS. As originally proposed, UWSS is aimed in obtaining experimental inputs for the Lagrangian analysis used to determine the dynamic behavior of materials. The new method to determine also the shock Hugoniot stress-strain curves is proposed for PC at medium particle velocities up to about 1 km/s. The revised, unsteady wave sensing system (M-UWSS, which we proposed before) using plate impact experiment with three PVDF gauges embedded is applied to construct stress-strain curves under shock loading up to Hugoniot stress σH and Hugoniot strain εH. Linear relationship between shock velocity Us and particle velocity Up: Us = C0+ S x Up, where C0 and S are material constants, is used to determine the constant S, since the constant C0 is determined as bulk sound velocity at ambient pressure. By using the momentum conservation and the mass conservation relations, S = (1 - C0 / CH) /εH, is derived from the linear relationship described above, where , CH =(σ H/ρ/εH)1/2 is density and CH ≈ Us. © (2011) Trans Tech Publications.


Wada E.,University of Tokyo | Yoshida M.,University of Tokyo | Kojima Y.,National Institute of Neuroscience | Nonaka I.,National Institute of Neuroscience | And 7 more authors.
American Journal of Pathology | Year: 2014

Duchenne muscular dystrophy is a lethal X-linked disease with no effective treatment. Progressive muscle degeneration, increased macrophage infiltration, and ectopic calcification are characteristic features of the mdx mouse, a murine model of Duchenne muscular dystrophy. Because dietary phosphorus/phosphate consumption is increasing and adverse effects of phosphate overloading have been reported in several disease conditions, we examined the effects of dietary phosphorus intake in mdx mice phenotypes. On weaning, control and mdx mice were fed diets containing 0.7, 1.0, or 2.0 g phosphorus per 100 g until they were 90 days old. Dystrophic phenotypes were evaluated in cryosections of quadriceps and tibialis anterior muscles, and maximal forces and voluntary activity were measured. Ectopic calcification was analyzed by electron microscopy to determine the cells initially responsible for calcium deposition in skeletal muscle. Dietary phosphorus overload dramatically exacerbated the dystrophic phenotypes of mdx mice by increasing inflammation associated with infiltration of M1 macrophages. In contrast, minimal muscle necrosis and inflammation were observed in exercised mdx mice fed a low-phosphorus diet, suggesting potential beneficial therapeutic effects of lowering dietary phosphorus intake on disease progression. To our knowledge, this is the first report showing that dietary phosphorus intake directly affects muscle pathological characteristics of mdx mice. Dietary phosphorus overloading promoted dystrophic disease progression in mdx mice, whereas restricting dietary phosphorus intake improved muscle pathological characteristics and function. © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.


PubMed | Kobayashi Institute of Physical Research, Hitachi Ltd., National Institute of Neuroscience and University of Tokyo
Type: Journal Article | Journal: The American journal of pathology | Year: 2014

Duchenne muscular dystrophy is a lethal X-linked disease with no effective treatment. Progressive muscle degeneration, increased macrophage infiltration, and ectopic calcification are characteristic features of the mdx mouse, a murine model of Duchenne muscular dystrophy. Because dietary phosphorus/phosphate consumption is increasing and adverse effects of phosphate overloading have been reported in several disease conditions, we examined the effects of dietary phosphorus intake in mdx mice phenotypes. On weaning, control and mdx mice were fed diets containing 0.7, 1.0, or 2.0 g phosphorus per 100 g until they were 90 days old. Dystrophic phenotypes were evaluated in cryosections of quadriceps and tibialis anterior muscles, and maximal forces and voluntary activity were measured. Ectopic calcification was analyzed by electron microscopy to determine the cells initially responsible for calcium deposition in skeletal muscle. Dietary phosphorus overload dramatically exacerbated the dystrophic phenotypes of mdx mice by increasing inflammation associated with infiltration of M1 macrophages. In contrast, minimal muscle necrosis and inflammation were observed in exercised mdx mice fed a low-phosphorus diet, suggesting potential beneficial therapeutic effects of lowering dietary phosphorus intake on disease progression. To our knowledge, this is the first report showing that dietary phosphorus intake directly affects muscle pathological characteristics of mdx mice. Dietary phosphorus overloading promoted dystrophic disease progression in mdx mice, whereas restricting dietary phosphorus intake improved muscle pathological characteristics and function.


Shiomi Y.,Kansai University | Onishi K.,Kansai University | Nakiri T.,Kansai University | Imoto K.,Imoto Mechanical Engineering Co. | And 5 more authors.
Japanese Journal of Applied Physics | Year: 2013

By using additives to change the higher-order structure of a poly(L-lactide) (PLLA) film, an improvement in its piezoelectricity was realized. The additive used was a triblock copolymer, which is a pure acrylic symmetric block copolymer consisting of a center block of poly(butyl acrylate) (PBA), corresponding to its soft part, and two side blocks of poly(methyl methacrylate) (PMMA), corresponding to its hard part. The triblock copolymer is hereafter denoted as PMMA-b-PBA-b-PMMA. The piezoelectric e-constant of the PLLA film with added PMMA-b-PBA-b-PMMA (PLLA/PMMA-PBA-PMMA film) was over two times higher than that of the PLLA film without adding PMMA-b-PBA-b-PMMA (reference PLLA film). Also, we found that the glass transition temperature increases with increasing PMMA-b-PBA-b-PMMA content. From atomic force microscopy (AFM) images, it was found that a new higher-order structure was formed in the PLLA/PMMA-PBA-PMMA film with high piezoelectricity. The method of using PMMA-b-PBA-b-PMMA has high productivity and its promising for industrial use. © 2013 The Japan Society of Applied Physics.


Kunimatsu S.,Japan National Institute of Advanced Industrial Science and Technology | Hirao Y.,Kobayashi Institute of Physical Research | Kitamura Y.,Construction Engineering Research Institute Foundation
Journal of Modern Transportation | Year: 2012

Ground-borne vibrations caused by vibration sources such as road traffic and construction exhibit complicated properties during propagation from the vibration source to the inside of a building. In the present paper, a numerical analysis technique for the system of vibration source and propagation path of ground vibration is developed in order to systematically determine the propagation properties of the vibration as part of developing a predictive technique for exposure evaluations by vibrations in three directions at receiving points of vibration in the human body. First, the exciting forces in three directions for input into the numerical computation are inversely-estimated by using the measured acceleration records of the measurement points, which are near the vibration source. The thin-layered element method is used for numerical computation of the ground vibration. Then, the calculation results for the ground vibration obtained by using the estimated exciting force are compared with the measured results, and the influence of the stratified structure of the ground on the exciting force and the propagation properties of the ground vibration are studied. From these results, in a prediction of the ground vibration in three directions, it is emphasized that it is necessary to consider the influence of horizontal exciting force, although attention has been paid to only the vertical exciting force for simulating ground vibration. © 2012 JMT. All rights reserved.


Motomatsu J.,Tokyo University of Agriculture and Technology | Kodama H.,Kobayashi Institute of Physical Research | Furukawa T.,Kobayashi Institute of Physical Research | Tominaga Y.,Tokyo University of Agriculture and Technology
Macromolecular Chemistry and Physics | Year: 2015

A new class of polymer electrolytes, consisting of poly(ethylene carbonate) (PEC) and metal salts, is expected to find application in all-solid-state batteries because of its excellent performance as an electrolyte. To study the ion-conductive mechanism in PEC-based electrolytes, broadband dielectric spectroscopy is used to analyze the correlation between dielectric relaxation and ionic conduction in PEC-lithium bis-(trifluoromethanesulfonyl) imide electrolytes over a broad range of salt concentration (0-150 mol%) at 40°C. The PEC system has two relaxation modes, α and β, associated respectively with the segmental motion and the local motion of PEC chains. The conductivity increases exponentially with increasing salt concentration, while the α relaxation frequency (fα) decreases with increasing strength (Δεα) at low salt concentrations, whereas in contrast fα increases with Δεα being saturated at high salt concentrations above 10 mol%. It is believed that the mobility of PEC segment at high concentration is enhanced by two factors. The first is that intermolecular interactions decrease, given the existence of many ion pairs and aggregated ions around saturated PEC domains where the dissociated ions are highly concentrated. The second is that intramolecular interactions between C=O and CH2 are lowered by the ion-dipole interaction. Poly(ethylene carbonate)-based electrolytes are promising materials for lithium batteries because of their unique ion-conductive properties. Broadband dielectric spectroscopy is used to investigate the correlation between ionic conductivity and dielectric relaxation, and additionally the FT-IR spectroscopy is used to investigate the conformation of polymer chains with ions. These results clarify the ion-conductive mechanism of novel decoupling polymer electrolyte systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ito S.,Imoto Mechanical Engineering Co. | Imoto K.,Imoto Mechanical Engineering Co. | Takai K.,Imoto Mechanical Engineering Co. | Kuroda S.,Imoto Mechanical Engineering Co. | And 6 more authors.
Japanese Journal of Applied Physics | Year: 2012

To realize a new polymer sensor fabricated from a piezoelectric chiral polymer fiber, we attempted to detect the response signal induced by the shear piezoelectricity of the chiral polymer poly(L-lactic acid) (PLLA) under the application of stress and strain, and we confirmed that the piezoelectric response signal was sufficiently large for use as a sensor signal. We then prepared a left-hand helical torsion coil (PLLA fiber lefthand coil), which was formed by drawing a PLLA fiber ten times. It was observed that, when twisted and released suddenly, the coil exhibited a torsion vibration, and we confirmed that the piezoelectric response signal followed the torsion vibration. Next, we prepared a system in which a PLLA fiber coil was linked to a personal computer used for simple image processing. The PLLA fiber left- and right-hand coils were placed on the arm of a subject, and the inward rotation and outward rotation of the forearm and upper arm were measured. Finally, using this system, we were able to visualize the rotation of the forearm and upper arm. © 2012 The Japan Society of Applied Physics.

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