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991.
Ogasawara T. Kubota Y. Makiura T. Akachi T. Hisanari T. Oda Y. Yasukochi K. 《IEEE transactions on magnetics》1983,19(3):248-251
Investigations of a.c. losses and stability of a mixed-matrix NbTi multifilamentary conductor are presented. Fine filament size of 1.0 μm and a tight twist of 5.5 times the wire diameter 0.2 mm result in a time constant of the eddy current of 0.024 msec at 1.0 T. If this conductor is used in superconducting armature windings of rotating machines or in a.c. magnets, generating a maximum field of 1.0 T, economical benefits are expected at operation frequencies below 20 Hz. 相似文献
992.
A three-dimensional (3D) Raman mapping system with a real-time calibration function was developed for detecting stress distributions in solid materials from subtle frequency shifts in Raman spectra. An atomic emission line of neon at 918.3 cm(-1) when excited at 514.5 nm was used as a wavenumber standard. An emission spectrum of neon and a Raman spectrum from a sample were introduced into a single polychromator using a bifurcated optical fiber. These two spectra were recorded simultaneously on a charge-coupled device (CCD) detector using double-track mode. Energy deviation induced by the fluctuation of laboratory temperature, etc., was removed effectively using the neon emission line. High stability during long measurements was achieved. By applying curve fitting, positions of the Raman line were determined with precision of about 0.05 cm(-1). The present system was applied to measurements of residual pressure around mineral inclusions in a natural diamond: 3D stress mapping was achieved. 相似文献
993.
Frédéric Caupin Satoshi Sasaki Sébastien Balibar 《Journal of Low Temperature Physics》2008,150(3-4):267-275
Supersolidity is a rather controversial issue which has been revived recently by a number of torsional oscillator (ac-rotation)
experiments with solid helium 4. One possibility would be that the ground state of helium 4 crystals contains a Bose-Einstein
condensate of mobile vacancies. However, the supersolid signal was shown to depend on sample history. In addition, dc-flow
experiments show that superfluid transport of mass does not occur in solid helium, except if it contains appropriate grain
boundaries. As a consequence, we believe that supersolidity is not an intrinsic property of helium single crystals, but that
it is due to quenched disorder. We report experiments on pressure relaxation in and light scattering from solid samples, that
give additional evidence for the existence of disorder in helium crystals. We also describe our recent study of the wetting
properties of grain boundaries.
相似文献
994.
Satoshi Murakawa Yuichiro Wada Yuta Tamura Masamichi Saitoh Yuki Aoki Ryuji Nomura Yuichi Okuda 《Journal of Low Temperature Physics》2008,150(3-4):154-159
We measured the complex transverse acoustic impedance of superfluid 3He in the B phase by coating a surface with 4He to study the boundary condition dependence of the surface bound states. Observed features in the temperature dependence
were similar to those without 4He coating. However, temperatures showing singularities became higher and variations in the dependence became smaller. The
small variations indicated that a specular surface was realized by the 4He coating. Increase in the singularity temperature indicated that the bandwidth of the surface Andreev bound states became
broader by the coating.
相似文献
995.
Wada S Yazawa A Hoshina T Kameshima Y Kakemoto H Tsurumi T Kuroiwa Y 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(9):1895-1899
Barium titanate (BaTiO3) nanoparticles from 27 to 192 nm were prepared by the 2-step thermal decomposition method from barium titanyl oxalate nanoparticles. These particles were dispersed well into 1-propanol, and dense BaTiO3 nanoparticle sphere arrays without stress-field were prepared by the meniscus method. Temperature dependence of dielectric properties was successfully measured using these dense nanoparticle sphere arrays, and size effect on dielectric properties was discussed. 相似文献
996.
Sukamon Hinchiranan Yi Zhang Satoshi Nagamori Tharapong Vitidsant Noritatsu Tsubaki 《Fuel Processing Technology》2008
The addition of small amount of TiO2 to silica-supported cobalt catalysts significantly increasing the dispersion of cobalt and Co metallic surface area resulting in the remarkable enhancement of the Fisher–Tropsch synthesis (FTS) activity in the slurry-phase reaction. The addition of TiO2 adjusted the interaction between cobalt and silica support quite well to realize the favorite dispersion and reduction degree of supported cobalt, leading to high catalytic activity in FTS. The properties of various catalysts were characterized by in-situ DRIFT, XRD, TPR, N2 physisorption and H2 chemisorption. 相似文献
997.
Effects of carbon source on denitrification efficiency and microbial community structure in a saline wastewater treatment process 总被引:3,自引:0,他引:3
Two different denitrifying reactors were monitored in order to evaluate the effects of carbon source on denitrification efficiency and microbial community structure under various saline conditions. Nitrogen removal performances were determined when salinity concentrations increase gradually in acetate- or methanol-fed denitrifying reactor. As a result, acetate-fed process attained high nitrate removal at 0-10% NaCl, while methanol was proven beneficial electron donors at 0-3% NaCl. A parallel analysis of T-RFLP and cloning in the acetate-fed sludge showed that a specialized microbial population (i.e. the genera Halomonas and Marinobacter) adapted to a high saline environment. Meanwhile, there were no major changes of bacterial populations in the methanol-fed reactor at 4% NaCl, although the relative abundances of the genera Azoarcus and Methylophaga increased when salinity concentration was at 1-3% NaCl, indicating that methanol-utilizing populations in activated sludge was unable to adapt to a high saline environments (>4% NaCl). 相似文献
998.
Martiradonna L Carbone L Tandaechanurat A Kitamura M Iwamoto S Manna L De Vittorio M Cingolani R Arakawa Y 《Nano letters》2008,8(1):260-264
A novel technique for the fabrication of photonic crystal (PC) nanocavities coupled with colloidal nanocrystals is presented. A waveguiding resist membrane embedding highly emitting dot-in-a-rod nanocrystals was patterned through e-beam lithography and released through wet etching process. The proposed approach makes the PC structure independent of fabrication imperfections induced by etching steps. Micro-photoluminescence spectra revealed degenerated resonant modes (Q-factor approximately 700) whose fabrication-induced spectral splitting is comparable to the full width at half-maximum of the peaks. Active nanocavities tunable from visible to infrared spectral range on GaAs or Si substrates can be easily implemented by this technique. 相似文献
999.
Koichiro Inomata Naomichi Ikeda Nobuki Tezuka Ryogo Goto Satoshi Sugimoto Marek Wojcik Eva Jedryka 《Science and Technology of Advanced Materials》2008,9(1)
The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD) using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co2Cr1 − xFexAl (CCFA(x)) and Co2FeSi1 − xAlx (CFSA(x)) and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR) of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs) using Co2FeSi0.5Al0.5 (CFSA(0.5)) Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5) at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001) substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5) electrodes depends on the structure, and is significantly higher for L21 than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe2 film deposited on a MgO (001) single crystal substrate, wherein the spinel structure of CoFe2O4 (CFO) and an epitaxial relationship of MgO(001)[100]/CoFe2 (001)]110]/CFO(001)[100] were induced. A SFD consisting of CoFe2 /CFO/Ta on a MgO (001) substrate exhibits the inverse TMR of - 124% at 10 K when the configuration of the magnetizations of CFO and CoFe2 changes from parallel to antiparallel. The inverse TMR suggests the negative spin polarization of CFO, which is consistent with the band structure of CFO obtained by first principle calculation. The - 124% TMR corresponds to the spin filtering efficiency of 77% by the CFO barrier. 相似文献
1000.