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Search Results: 1 - 10 of 2078 matches for " Hiroaki Kawasaki "
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Effects of Polysilane-Coating on Interface of Electrofusion Joints for Maintaining Strength  [PDF]
Hiroaki Murase, Shinichi Kawasaki, Toshimichi Kitaoka, Jouji Furukawa, Hirofumi Ueda, Hiroyuki Nishimura, Kazushi Yamada
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.64037
Abstract: The fusion strength of electrofusion joints using the polyethylene (PE) pipe connection greatly depends on the amount of sand which adheres to the interface by wind and so on, because there is no flow of melted resin at the fusion interface on electrofusion joints. Therefore, it is necessary to develop a method to prevent the fusion strength from reducing even in the case of sand adhesion. In this study, the fusion interface coated with polysilane, a kind of silicon polymer, effectively prevented the reduction of the fusion strength even if contaminated by sand. It was found that it brought the improvement of the fusion strength since when there was polysilane on the fusion interface. PS deeply permeated the polyethylene layer and lowered the viscosity of polyethylene.
Effect of Brewer's Yeast-Induced Pyrexia on Aminophylline-Elicited Convulsions in Mice
Acta Medica Okayama , 2009,
Abstract: Theophylline-associated convulsions have been observed most frequently in children with fever, but the mechanism is not fully understood. In this study, we investigated the basic mechanism of aminophylline [theophylline-2-ethylenediamine]-induced convulsions and the effects of Brewer's yeast-induced pyrexia in mice. Diazepam (5-10mg/kg, i.p.), a benzodiazepine receptor agonist, significantly prolonged the onset and significantly decreased the incidence of convulsions induced by aminophylline (350mg/kg, i.p.). However, the gamma aminobutyric acid (GABA)A receptor agonist muscimol (1-4mg/kg, i.p.), the GABAB receptor agonist baclofen (2-4mg/kg, i.p.) and the N-methyl-D-aspartic acid receptor antagonist dizocilpine (0.1-0.3mg/kg, i.p.) failed to protect against the convulsions. 20% Brewer's yeast (0.02ml/g, s.c.) increased body temperature by 1.03, and also significantly shortened the onset and significantly increased the incidence of convulsions induced by aminophylline. The anticonvulsant action of diazepam (2.5-10mg/kg, i.p.) on the convulsions induced by aminophylline was reduced by Brewer's yeast-induced pyrexia. The proconvulsant actions of the GABAA receptor antagonists picrotoxin (3-4mg/kg, i.p.) and pentylenetetrazol (40-60mg/kg, i.p.) were enhanced by Brewer's yeast. These results suggest that the anticonvulsant action of diazepam against aminophylline is reduced by Brewer's yeast-induced pyrexia, and that GABAA receptors are involved in the aggravation of the convulsions by Brewer's yeast in mice.
Proteomic analysis of endogenous nitrotryptophan-containing proteins in rat hippocampus and cerebellum
Munehiro Uda,Hiroaki Kawasaki,Ayako Shigenaga,Takeshi Baba
Bioscience Reports , 2012, DOI: 10.1042/bsr20120032
Abstract: Nitration of tryptophan residues is a novel post-translational modification. In the present study, we examined whether NO2Trp (nitrotryptophan)-containing proteins are produced in the hippocampus and cerebellum of the adult rat under physiological conditions in vivo. Using Western blot analysis with anti-6-NO2Trp-specific antibody, we found many similar immunoreactive spots in the protein extracts from both regions. These spots were subsequently subjected to trypsin digestion and LC-ESI-MS/MS (LC-electrospray ionization-tandem MS) analysis. We identified several cytoskeletal proteins and glycolytic enzymes as NO2Trp-containing proteins and determined the position of nitrated tryptophan residues with significant ion score levels (P<0.05) in several proteins in both regions. We also observed that the total amount of NO2Trp-containing proteins in the cerebellum was significantly greater than that in the hippocampus (P<0.05). Moreover, IP (immunoprecipitation) assays using anti-aldolase C antibody showed that the relative intensity of immunostaining for NO2Trp over aldolase C was much higher in cerebellum than in hippocampus. The amounts of nNOS (neuronal nitric oxide synthase) and eNOS (endothelial nitric oxide synthase) were much greater in cerebellum than in hippocampus. This is the first evidence of several specific sites of nitrated tryptophan in proteins under physiological conditions in vivo.
Fabrication of binary FeSe superconducting wires by novel diffusion process
Toshinori Ozaki,Keita Deguchi,Yoshikazu Mizuguchi,Yasuna Kawasaki,Takayoshi Tanaka,Takahide Yamaguchi,Hiroaki Kumakura,Yoshihiko Takano
Physics , 2011, DOI: 10.1063/1.4726243
Abstract: We report successful fabrication of multi- and mono-core FeSe wires with high transport critical current density Jc using a simple in-situ Fe-diffusion process based on the powder-in-tube (Fe-diffusion PIT) method. The seven-core wire showed transport Jc of as high as 1027 A/cm2 at 4.2 K. The superconducting transition temperature Tczero was observed at 10.5 K in the wire-samples, which is about 2 K higher than that of bulk FeSe. The Fe-diffusion PIT method is suitable for fabricating multi-core wires of the binary FeSe superconductors with superior properties.
Enhancing the Superconducting Transition Temperature in the Absence of Spin Correlations in Heavy Fermion Compound CeIrIn$_5$
Shinji Kawasaki,Guo-qing Zheng,Hiroki Kan,Yoshio Kitaoka,Hiroaki Shishido,Yoshichika ōnuki
Physics , 2004, DOI: 10.1103/PhysRevLett.94.037007
Abstract: We report on a pressure($P$)-induced evolution of superconductivity and spin correlations in CeIrIn$_5$ via the $^{115}$In nuclear-spin-lattice-relaxation rate measurements. We find that applying pressure suppresses dramatically the antiferromagnetic fluctuations that are strong at ambient pressure. At $P$ = 2.1 GPa, $T_{\rm c}$ increases to $T_{\rm c}$ = 0.8 K that is twice $T_{\rm c}$($P$ = 0 GPa), in the background of Fermi liquid state. This is in sharp contrast with the previous case in which negative, chemical pressure (replacing Ir with Rh) enhances magnetic interaction and increases $T_{\rm c}$. Our results suggest that multiple mechanisms work to produce superconductivity in the same compound CeIrIn$_5$.
Enhancing the Superconducting Transition Temperature due to Strong-Coupling Effect under Antiferromagnetic Spin Fluctuations in CeRh1-xIrxIn5 : 115In-NQR Study
Shinji Kawasaki,Mitsuharu Yashima,Yoichi Mugino,Hidekazu Mukuda,Yoshio Kitaoka,Hiroaki Shishido,Yoshichika Onuki
Physics , 2006, DOI: 10.1103/PhysRevLett.96.147001
Abstract: We report on systematic evolutions of antiferromagnetic (AFM) spin fluctuations and unconventional superconductivity (SC) in heavy-fermion (HF) compounds CeRh$_{1-x}$Ir$_{x}$In$_5$ via $^{115}$In nuclear-quadrupole-resonance (NQR) experiment. The measurements of nuclear spin-lattice relaxation rate $1/T_1$ have revealed the marked development of AFM spin fluctuations as a consequence of approaching an AFM ordered state with increasing Rh content. Concomitantly the superconducting transition temperature $T_{\rm c}$ and the energy gap $\Delta_0$ increase drastically from $T_{\rm c} = 0.4$ K and $2\Delta_0/k_{\rm B}T_{\rm c} = 5$ in CeIrIn$_5$ up to $T_{\rm c} = 1.2$ K and $2\Delta_0/k_{\rm B}T_{\rm c} = 8.3$ in CeRh$_{0.3}$Ir$_{0.7}$In$_5$, respectively. The present work suggests that the AFM spin fluctuations in close proximity to the AFM quantum critical point are indeed responsible for the onset of strong-coupling unconventional SC with the line node in the gap function in HF compounds.
New Superconducting and Magnetic Phases Emerge on the Verge of Antiferromagnetism in CeIn$_3$
Shinji Kawasaki,Takeshi Mito,Yu Kawasaki,Hisashi Kotegawa,Guo-qing Zheng,Yoshio Kitaoka,Hiroaki Shishido,Shingo Araki,Rikio Settai,Yoshichika ōnuki
Physics , 2004, DOI: 10.1143/JPSJ.73.1647
Abstract: We report the discovery of new superconducting and novel magnetic phases in CeIn$_3$ on the verge of antiferromagnetism (AFM) under pressure ($P$) through the In-nuclear quadrupole resonance (NQR) measurements. We have found a $P$-induced phase separation of AFM and paramagnetism (PM) without any trace for a quantum phase transition in CeIn$_3$. A new type of superconductivity (SC) was found in $P=2.28-2.5$ GPa to coexist with AFM that is magnetically separated from PM where the heavy fermion SC takes place. We propose that the magnetic excitations such as spin-density fluctuations induced by the first-order magnetic phase transition might mediate attractive interaction to form Cooper pairs.
A 7-Year-Old Boy with Light Cupula of the Horizontal Semicircular Canal  [PDF]
Hiroaki Ichijo
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2014, DOI: 10.4236/ijohns.2014.32018

Report of childhood positional vertigo is very rare. We present a 7-year-old boy who revealed persistent direction-changing geotropic positional nystagmus. In the supine position, horizontal nystagmus toward the left continued as long as the position was maintained. However, it ceased when the head was turned to the right side by 45°. With greater head turn (right-ear-down), nystagmus toward the right lasted for more than 1 minute. In the left-ear-down position, horizontal nystagmus toward the left occurred and lasted for more than 1 minute. After the disappearance of positional nystagmus, we detected canal paresis of the right ear by caloric test. We considered that the pathophysiology of the persistent type of geotropic nystagmus is a result of light debris cupulolithiasis of the horizontal canal.

Determination of Shear Center of Arbitrary Cross-Section  [PDF]
Hiroaki Katori
World Journal of Mechanics (WJM) , 2016, DOI: 10.4236/wjm.2016.68020
Abstract: In structural analysis, it is often necessary to determine the geometrical properties of cross section. The location of the shear center is greater importance for an arbitrary cross section. In this study, the problems of coupled shearing and torsional were analyzed by using the finite element method. Namely, the simultaneous equations with respect to the warping, shear deflection, angle of torsion and Lagrange’s multipliers are derived by finite element approximation. Solving them numerically, the matrix of the shearing rigidity and torsional rigidity is obtained. This matrix indicates the coupled shearing and torsional deflection. The shear center can be obtained determining the coordinate axes so as to eliminate the non-diagonal terms. Several numerical examples are performed and show that the present method gives excellent results for an arbitrary cross section.
Inverse Problems for an Euler-Bernoulli Beam: Identification of Bending Rigidity and External Loads  [PDF]
Hiroaki Katori
World Journal of Mechanics (WJM) , 2018, DOI: 10.4236/wjm.2018.85014
Abstract: We present a method for identifying the flexural rigidity and external loads acting on a beam using the finite-element method. We used mixed beam elements possessing transverse deflection and the bending moment as the primary degrees of freedom. The first step is to determine the bending moment from the transverse deflection and boundary conditions. The second step is to substitute the bending moment into the final equations with respect to the unknown parameters (flexural rigidity or external load). The final step solves the resulting system of equations. We apply this method to some inverse beam problems and provide an accurate estimation. Several numerical examples are performed and show that present method gives excellent results for identifying bending stiffness and distributed load of beam.
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