1,720,998 research outputs found
Thermophysical properties of liquid UO2, ZrO2 and corium by molecular dynamics and predictive models
No full textPredicting the fate of accident-melted nuclear fuel-cladding requires the understanding of the thermophysical properties which are lacking or have large scatter due to high-temperature experimental challenges. Using equilibrium classical molecular dynamics (MD), we predict the properties of melted UO2 and ZrO2 and compare them with the available experimental data and the predictive models. The existing interatomic potential models have been developed mainly for the polymorphic solid phases of these oxides, so they cannot be used to predict all the properties accurately. We compare and decipher the distinctions of those MD predictions using the specific property-related autocorrelation decays. The predicted properties are density, specific heat, heat of fusion, compressibility, viscosity, surface tension, and the molecular and electronic thermal conductivities. After the comparisons, we provide readily usable temperature-dependent correlations (including UO2-ZrO2 compounds, i.e. corium melt). (C) 2017 Elsevier B.V. All rights reserved.113sciescopu
An optical sensor of a probing system for inspection of PCBs
No full textCopyright 1998 Society of Photo-Optical Instrumentation Engineers
Metal-insulator transition and the role of electron correlation in FeO2
No full textIron oxide is a key compound to understand the state of the deep Earth. It has been believed that previously known oxides such as FeO and Fe2O3 will be dominant at the mantle conditions. However, the recent observation of FeO2 shed another light to the composition of the deep lower mantle (DLM), and thus understanding of the physical properties of FeO2 will be critical to model the DLM. Here, we report the electronic structure and structural properties of FeO2 by using density functional theory and dynamic mean-field theory. The crystal structure of FeO2 is composed of Fe2+ and O22- dimers, where the Fe ions are surrounded by the octahedral O atoms. We found that FeO2 shows a metal-insulator transition (MIT) under high pressure. The MIT is not a Mott type but a band insulator type which is driven by the O2 dimer bond length change. However, the correlation effect of Fe 3d orbitals should be considered to correctly describe O2 dimer bond length of FeO2 and the MIT. ? 2017 American Physical Society.11sciescopu
Electrodynamic Force Derived in-Channel Separation and Detection of Au Nanoparticles Using an Electrochemical AC Microfluidic Channel
No full textIn this study, we have established the separation of Au nanoparticles (AuNPs) using a symmetrical AC electric field applied-electrochemical microfluidic device composed of carbon channel and detection electrodes. The lateral movement of AuNPs in the channel under the AC field was analyzed by simulation using the mathematically derived equations, which were formulated from Newtonian fluid mechanics. It shows that the nanoparticles are precisely separated according to their respective mass or size difference in a short time. The experimental parameters affecting the separation and detection of AuNPs were optimized in terms of applied frequency, amplitude, flow rate, buffer concentration, pH dependency, and temperature. The final separation was performed at 1.0 V amplitude with 8.0 MHz frequency at 0.4 mu L/min flow rate for the separation, and the potential of 1.0 V was applied for the amperometric detection of AuNPs in a 0.1 M PBS. Before and after the separation, AuNPs (diameter range: 3-60 nm) were confirmed by UV-visible spectroscopy and transmission electron microscopy. In this case, the separation resolution was 3 nm with an enhanced separation efficiency of up to 597,503 plates/m for the AuNPs. In addition, the amperometric current response of the detection electrode under the AC field application was also enhanced by the sensitivity 5-fold compared with the absence of the AC field.11Nsciescopu
Kinematic feature analysis of a 6-degree-of-freedom in-parallel manipulator for micro-positioning
No full textGiant Rashba-Type Spin Splitting in Bi/Ag(111) from Asymmetric Interatomic-Hopping
No full textRashba-type spin splitting (RSS) has recently drawn added attention due to its central role in the field of spintronics. In that regards, designing materials with giant RSS is highly desirable for practical spintronic applications, and thus disclosing the origin of the giant RSS could pave the way. Here, we theoretically demonstrate that the giant RSS observed in Bi/Ag(111) alloy system emerges from the difference in kinetic energy or interatomic-hopping strength, not from a uniform electric field. Our density functional theory calculation and tight-binding analysis show that depending on the chirality of orbital angular momentum (OAM), the Bi orbital forms an asymmetric charge distribution in the direction towards or away from the Ag atom. As a result, opposite OAM chirality results in difference in hopping strength between Bi and Ag orbitals, and this kinetic energy difference dominates the size of RSS. This new interpretation on the RSS successfully explains the giant RSS in Bi/Ag(111) surface states and has implication for the RSS mechanism in general
Direct visualization of coexisting channels of interaction in CeSb
Full text linkOur understanding of correlated electron systems is vexed by the complexity of their interactions. Heavy fermion compounds are archetypal examples of this physics, leading to exotic properties that weave magnetism, superconductivity and strange metal behavior together. The Kondo semimetal CeSb is an unusual example where different channels of interaction not only coexist, but have coincident physical signatures, leading to decades of debate about the microscopic picture describing the interactions between the f moments and the itinerant electron sea. Using angle-resolved photoemission spectroscopy, we resonantly enhance the response of the Ce f electrons across the magnetic transitions of CeSb and find there are two distinct modes of interaction that are simultaneously active, but on different kinds of carriers. This study reveals how correlated systems can reconcile the coexistence of different modes on interaction-by separating their action in momentum space, they allow their coexistence in real space.11Ysciescopu
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Evolution of the Kondo lattice electronic structure above the transport coherence temperature
Full text linkThe temperature-dependent evolution of the Kondo lattice is a long-standing topic of theoretical and experimental investigation and yet it lacks a truly microscopic description of the relation of the basic f-c hybridization processes to the fundamental temperature scales of Kondo screening and Fermi-liquid lattice coherence. Here, the temperature dependence of f-c hybridized band dispersions and Fermi-energy f spectral weight in the Kondo lattice system CeCoIn5 is investigated using f-resonant angle-resolved photoemission spectroscopy (ARPES) with sufficient detail to allow direct comparison to first-principles dynamical mean-field theory (DMFT) calculations containing full realism of crystalline electric-field states. The ARPES results, for two orthogonal (001) and (100) cleaved surfaces and three different f-c hybridization configurations, with additional microscopic insight provided by DMFT, reveal f participation in the Fermi surface at temperatures much higher than the lattice coherence temperature, T* approximate to 45 K, commonly believed to be the onset for such behavior. The DMFT results show the role of crystalline electric-field (CEF) splittings in this behavior and a T-dependent CEF degeneracy crossover below T* is specifically highlighted. A recent ARPES report of low T Luttinger theorem failure for CeCoIn5 is shown to be unjustified by current ARPES data and is not found in the theory.11Nsciescopu
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