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Your search keyword '"Ezaki, S."' showing total 147 results
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147 results on '"Ezaki, S."'

1. Two-level system loss: Significant not only at millikelvin.

Author

Shan, W. and Ezaki, S.

Subjects
*LIQUID helium, *DIELECTRIC loss, *DIELECTRIC materials, *ELECTRIC lines, *AMORPHOUS substances
Abstract

Tow-level system (TLS) loss in amorphous dielectric materials has been intensively studied at millikelvin temperatures due to its impact on superconducting qubit devices and incoherent detectors. However, the significance of TLS loss in superconducting transmission lines at liquid helium temperatures remains unclear. This study investigates TLS loss in amorphous SiO 2 at liquid helium temperatures (about 4 K) within a frequency range of 130–170 GHz, using niobium microstrip and coplanar waveguide resonators. Our results demonstrate notable power and temperature dependence of dielectric loss, with the dielectric loss and quasiparticle loss exchanging dominance at around 4 K. These findings are consistent with TLS models and provide crucial insight for the design of superconducting devices operating at liquid helium temperatures. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Crossover from weak localization to anti-weak localization in indium oxide systems with wide range of resistivity.

Author

Shinozaki, B., Hidaka, K., Ezaki, S., Makise, K., Asano, T., Tomai, S., Yano, K., and Nakamura, H.

Subjects
WEAK localization (Quantum mechanics), INDIUM oxide, ELECTRICAL resistivity, MAGNETIC fields
Abstract

We investigated the magnetoconductivity Δσ(H)≡1/ρ(H)-1/ρ(0) in a wide range of magnetic fields for three-dimensional indium oxide films doped with zinc, tin, or gallium in the range of resistivity ρ(300K) between 4.1×10-6 Ωm and 1.7×10-3 Ωm. The weak localization theory was fitted to data for Δσ(H) at various temperatures in the range 2.0 K≤T≤50 K by the use of suitable characteristics Dτin(T) and Dτso, where D, τin, and τso are the electron diffusion constant, inelastic scattering time, and spin-orbit (s-o) scattering time, respectively. It was found that (i) for films with a large value of ρ, the sign of Δσ(H) changes from positive to negative with decreasing temperature as a precursor to an anti-weak localization effect; (ii) the ratio τso/τin decreases from ≈4000 to≈4.0 with increasing ρ; (iii) the strong ρ dependence of Dτso cannot be explained by the model with a constant atomic number Z in a formula τso∝1/Z4 proposed by Abrikozov and Gorkov Zh. Eksp. Teor. Fiz. 42, 1088 (1962); [Sov. Phys. JETP 15, 752 (1962)]. As a reason for this ρ dependence, we suggest that the s-o scattering changes with increasing ρ from light oxygen atoms to heavy atoms, i.e., indium, zinc, and gallium, because of the decrease in the number of oxygen vacancies acting as s-o scattering centers. [ABSTRACT FROM AUTHOR]

Published
2013
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40. 3116

Author

Moon, Y., primary, Ezaki, S., additional, Kawaguchi, T., additional, Kobayashi, T., additional, Iijima, T., additional, Kawanishi, J., additional, Numazaki, H., additional, Noguchi, N., additional, and Iwao, H., additional

Published
2006
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45. Presence of a structurally novel type ribulose-bisphosphate carboxylase/oxygenase in the hyperthermophilic archaeon, Pyrococcus kodakaraensis KOD1.

Author

Ezaki, S, Maeda, N, Kishimoto, T, Atomi, H, and Imanaka, T

Abstract

We have characterized the gene encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of the hyperthermophilic archaeon, Pyrococcus kodakaraensis KOD1. The gene encoded a protein consisting of 444 amino acid residues, corresponding in size to the large subunit of previously reported Rubiscos. Rubisco of P. kodakaraensis KOD1 (Pk-Rubisco) showed only 51.4% similarity with the large subunit of type I Rubisco from spinach and 47.3% with that of type II Rubisco from Rhodospirillum rubrum, suggesting that the enzyme was not a member of either type. Active site residues identified from type I and type II Rubiscos were conserved. We expressed the gene in Escherichia coli, and we obtained a soluble protein with the expected molecular mass and N-terminal amino acid sequence. Purification of the recombinant protein revealed that Pk-Rubisco was an L8 type homo-octamer. Pk-Rubisco showed highest specific activity of 19.8 x 10(3) nmol of CO2 fixed per min/mg, and a tau value of 310 at 90 degreesC, both higher than any previously characterized Rubisco. The optimum pH was 8.3, and the enzyme possessed extreme thermostability, with a half-life of 15 h at 80 degreesC. Northern blot analysis demonstrated that the gene was transcribed in P. kodakaraensis KOD1. Furthermore, Western blot analysis with cell-free extract of P. kodakaraensis KOD1 clearly indicated the presence of Pk-Rubisco in the native host cells.

Published
1999

49. Recent developments of the ISP operations at Harima works.

Author

Tomono M., Ezaki S., Makino S., Yamada K., Tomono M., Ezaki S., Makino S., and Yamada K.

Abstract

Two developments are described. Firstly, the furnace bottom design was modified for the purpose of reducing carbon consumption ratio. As a result, shaft operating condition has been satisfactory, carbon consumption ratio was improved by 2% and furnace zinc production increased by about 8%. Secondly, the oxygen enriched operation at sintering machines was tested from July 1984 to June 1985, in order to increase the sinter productivity, and to solve the capacity imbalance between sinter plant and ISP. It was found that the sulphur elimination rate was increased by approximately 10% with oxygen enrichment of 500 Nm3/hr., Two developments are described. Firstly, the furnace bottom design was modified for the purpose of reducing carbon consumption ratio. As a result, shaft operating condition has been satisfactory, carbon consumption ratio was improved by 2% and furnace zinc production increased by about 8%. Secondly, the oxygen enriched operation at sintering machines was tested from July 1984 to June 1985, in order to increase the sinter productivity, and to solve the capacity imbalance between sinter plant and ISP. It was found that the sulphur elimination rate was increased by approximately 10% with oxygen enrichment of 500 Nm3/hr.

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