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481.
Hideo Harada Atsushi Kimura Fumito Kitatani Mitsuo Koizumi Harufumi Tsuchiya Bjorn Becker 《Journal of Nuclear Science and Technology》2013,50(6):837-843
Neutron resonance densitometry (NRD) is a non-destructive analysis method, which can be applied to quantify special nuclear materials (SNM) in small particle-like debris of melted fuel that are formed in severe accidents of nuclear reactors such as the Fukushima Daiichi nuclear power plants. NRD uses neutron resonance transmission analysis (NRTA) to quantify SNM and neutron resonance capture analysis (NRCA) to identify matrix materials and impurities. To apply NRD for the characterization of arbitrary-shaped thick materials, a generalized method for the analysis of NRTA data has been developed. The method has been applied on data resulting from transmission through thick samples with an irregular shape and an areal density of SNM up to 0.253 at/b (≈100 g/cm2). The investigation shows that NRD can be used to quantify SNM with a high accuracy not only in inhomogeneous samples made of particle-like debris but also in samples made of large rocks with an irregular shape by applying the generalized analysis method for NRTA. 相似文献
482.
Ishizaka K Bahramy MS Murakawa H Sakano M Shimojima T Sonobe T Koizumi K Shin S Miyahara H Kimura A Miyamoto K Okuda T Namatame H Taniguchi M Arita R Nagaosa N Kobayashi K Murakami Y Kumai R Kaneko Y Onose Y Tokura Y 《Nature materials》2011,10(7):521-526
There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin-orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin-orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions. 相似文献
483.
The aim of this study is to reveal the temporal and spatial heat transfer performance of an isothermally heated sphere placed in a uniform, downwardly directed flow using a micro-foil heat flow sensor (HFS). A HFS, whose response time is about 0.02 s, was pasted on the surface of a heated copper sphere. Experiments were carried out using air with a Grashof number of 3.3 × 105 and with several Reynolds numbers (Re) up to 1800. Three flow patterns appeared: a chaotic flow at Re<240; a two-dimensional steady separated flow at 240 Re<500, and a three-dimensional unsteady separated flow at Re 500. In addition, the instantaneous and time-averaged heat transfer performance around the sphere in each of the three regions was clarified. Next, enhancement of the latent heat storage rate of a solid phase change material (PCM) in a spherical capsule was performed. The flow around the spherical capsule, in which the solid PCM was filled and placed in a heated, upwardly directed flow, is the approximate adverse flow phenomenon around the heated sphere which was placed in a downwardly directed flow. In other words, the buoyant flow and the forced flow are in the opposite directions in these two cases. Tests of latent heat storage were run for two Reynolds numbers which represented different flow characteristics in the heat transfer experiments, Re=150 and 1800. Furthermore, copper plates were inserted into the solid PCM, of which thermal conductivity was considerably low, to enhance the latent heat storage rate for the two Reynolds number flows. 相似文献
484.
Hydrothermal synthesis of LiFePO<Subscript>4</Subscript> as a cathode material for lithium batteries
LiFePO4 (space group: Pnma) was prepared by hydrothermal method at 170 °C. LiFePO4 was prepared from precursor solutions consisting of FeSO4 · 7H2O, (NH4)2HPO4, and three kinds of Li sources. LiCl, Li(CH3COO), and LiOH · H2O were used as Li sources. The pH of the precursor solution varied depending on Li source. The particle size, particle shape,
and crystal texture of the obtained LiFePO4 changed depending on pH. The electrochemical properties of the prepared LiFePO4 were characterized as a cathode material for lithium batteries in an organic electrolyte at room temperature. The LiFePO4 particle prepared from the precursor solution with Li(CH3COO) was flake-like crystal (particle size: 1–2 μm) and had a preferred crystal orientation with a (020) texture. This LiFePO4 exhibited a discharge capacity of 147 mA h g−1, which was 85% of the theoretical capacity 170 mA h g−1. 相似文献
485.
Takehisa Mochizuki Daichi Hongo Takuya Satoh Naoto Koizumi Muneyoshi Yamada 《Catalysis Letters》2008,121(1-2):52-57
Co/SiO2 catalysts were prepared by a stepwise impregnation of aqueous solutions containing Co nitrate or chelating agent, nitrilotriacetic
acid (NTA) or trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA), with various concentrations of Co2+ and the chelating agent. Fischer–Tropsch synthesis activity of Co/SiO2 catalysts having Co loadings of 5–20 mass% as metallic Co was improved by the stepwise impregnation method with these chelating
agents. The catalyst prepared with CyDTA (Co loading = 20 mass%, Co2+/CyDTA = 4 mol mol−1) yielded 1,500 and 815 g kg-cat−1 h−1 of C5+ and C10–20 hydrocarbons at 503 K and 1.1 MPa, respectively, which was much greater than that with the catalyst prepared from the aqueous
solution containing both Co nitrate and NTA. 相似文献
486.