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151.
Masaoki Oku Jin Kimura Minoru Hosoya Kunio Takada Kichinosuke Hirokawa 《Fresenius' Journal of Analytical Chemistry》1988,332(3):237-241
Summary Oxidation-reduction titration methods, Fe2+-Cr2C
7
2–
and I–-S2O
3
2–
, were applied to the determination of the oxidation state of copper in the superconductor YBa2Cu3O
y
, and related compounds. The former method presented problems in the sample dissolution and titration steps. The dissolution of the sample in low concentrations of Fe+-phosphoric acid and Fe2+-perchloric acid takes place in two steps, the oxidation of Fe2+ to Fe3+ and the liberation of oxygen gas, when the liberation results in low analytical values for Cu+. In addition the coexistence of cuprous ion and acids induces the oxidation of ferrous ion by dissolved oxygen and air. The problems were resolved by dissolution in 0.1 mol/l Fe2+-phosphoric acid and titration in an argon atmosphere. The latter method gave good results by controlling the amounts of potassium chloride, the concentration of acetic acid, and by elimination of the dissolved oxygen in acetic acid solution. The results of the two titration methods coincided with each other.
Anwendung der Eisen(II)-Chromat- und der iodometrischen Titration zur Bestimmung der Oxidationsstufe des Kupfers im Supraleiter YBa2Cu3O y相似文献
152.
N.N. Nedyalkov H. Takada M. Obara 《Applied Physics A: Materials Science & Processing》2006,85(2):163-168
High-energy synchrotron X-ray diffraction and imaging experiments were performed at the Advanced Photon Source on two ancient
Chinese bronzes from the Art Institute of Chicago with the goal to nondestructively study their microstructure. The first
object, a bronze fragment from an early Western Zhou dynasty vessel (Hu, 11th/10th century B.C.), was investigated with spatially-resolved
diffraction to reveal the depth and composition of the surface corrosion layer as well as the composition and grain size of
the underlying bronze core. The second object, a bronze dagger-axe (Ge, 3rd/2nd century B.C.) with a silver-inlaid sheath,
was studied under both diffraction and imaging conditions. It was found to have been cast as a single object, answering longstanding
scholars’ questions on whether the ceremonial object concealed an interior blade.
PACS 81.00; 01.75.+m 相似文献
153.
The objective of the present in vitro study was to examine the effect of various root surface treatments on the initial attachment of gingival fibroblasts. Cultured fibroblasts were well spread and attached to demineralized dentin with citric acid, superficially curetted cementum, and root surface with periodontal ligament, while those on the planed dentin showed a poorly spread appearance. The first three root surfaces exhibited rough and irregular surface appearances with a well-developed filopodia and the latter root surface exhibited a smooth appearance, suggesting the texture of the root surface is closely associated with cell attachment. Interiorized collagen fibrils and numerous cytoplasmic vesicles were seen along the cell membrane of fibroblasts facing the root surfaces of the planed dentin, demineralized dentin, and superficially curetted cementum. Thus even the artificially exposed tooth surface with citric acid may be subjected to further alteration by fibroblasts. 相似文献
154.
155.
A two‐dimensional 19‐velocity (D2Q19) lattice Boltzmann model which satisfies the conservation laws governing the macroscopic and microscopic mass, momentum and energy with local equilibrium distribution order O(u4) rather than the usual O(u3) has been developed. This model is applied to simulate the reflection of shockwaves on the surface of a triangular obstacle. Good qualitative agreement between the numerical predictions and experimental measurements is obtained. As the model contains the higher‐order terms in the local equilibrium distribution, it performs much better in terms of numerical accuracy and stability than the earlier 13‐velocity models with the local equilibrium distribution accurate only up to the second order in the velocity u. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
156.
Tsukada K. Kawai J. Takada Y. Adachi A. 《Applied Superconductivity, IEEE Transactions on》1995,5(3):3488-3493
The transfer function dV/dΦ and the noise characteristics of a low-Tc superconducting quantum interference device (SQUID) have been improved by annealing to adjust the critical current, thereby optimizing the McCumber parameter βc. A SQUID structure suitable for annealing and using surface nitridation and planarization has also been developed. By annealing a SQUID that initially has a βc greater than 1, the I-V characteristics can be changed from characteristics with hysteresis to characteristics without hysteresis. A SQUID with βc=0.81, close to the hysteresis limitation, had a large dV/dΦ (3.7 mV/Φ) and good noise characteristics (1.5 μΦ0/√(Hz) at 100 Hz and 3.0 μΦ0/√(Hz) at 1 Hz). These characteristics can be attained even when using a simple measuring circuit connected directly to preamplifier without adaptive components such as flux modulation or additional positive feedback (APF) 相似文献
157.
The first demonstration to compress the linearly chirped optical pulses from a gain-switched distributed-feedback laser diode (DFB-LD) is described at 1.3 ?m wavelength. By travelling through a highly dispersive single-mode fibre with 48 ps/nm normal dispersion, a 26 ps (FWHM) pulse having red-shift frequency chirping of 85 GHz (FWHM) is compressed to 8.3 ps with the time-bandwidth product of 0.71. 相似文献
158.
An all-optical spatial time-division multiplexer is demonstrated using fibre-type 2×2 couplers and fibre delay lines. 100 Gbit/s modulated optical signals are successfully generated by 32-times multiplication of 3.125 Gbit/s, 6 ps compressed pulses, from a gain-switched DFB laser diode 相似文献
159.
We describe a jaggedness-free optical low coherence reflectometer (OLCR) with a high power tunable narrow-band light source which employs a fluoride-based erbium-doped fiber amplifier. The use of the amplifier simplifies the structure of the source and enables us to generate narrow-band light with a power of 18±0.2 dBm in the 1530-1560 nm wavelength range and with a reduced background level in each spectrum. The OLCR achieves a dynamic range of 47 dB and the signal fluctuations caused by residual speckle-like noise in the Rayleigh backscattering measurement are less than ±1 dB. This is the best data yet obtained with a diode-pumped fiber amplifier. The diagnosis of fiber-optic attenuators is successfully demonstrated using the OLCR 相似文献
160.
Abe K Amako K Arai Y Asano Y Chiba M Chiba Y Daigo M Emura T Endo I Fukawa M Fukui T Fukushima Y Haba J Haidt D Hayashibara I Hemmi Y Higuchi M Hirose T Hojyo Y Homma Y Hoshi Y Ikegami Y Ishihara N Kamitani T Kanematsu N Kanzaki J Kikuchi R Kondo T Koseki T Kubo K Kurashige H Matsui T Minami M Miyake K Mori S Nagashima Y Nakamura T Nakano I Odaka S Ogawa K Ohama T Ohsugi T Ono A Osabe H Saito H Sakae H Sakamoto H Sakamoto S Sakano M Sakuda M Sasao N Sato M Shioden M Shirai J Suekane F 《Physical review letters》1988,61(8):915-918