A lattice Boltzmann method for two-phase immiscible fluids with large density differences is proposed. The difficulty in the treatment of large density difference is resolved by using the projection ...method. The method can be applied to simulate two-phase fluid flows with the density ratio up to 1000. To show the validity of the method, we apply the method to the simulations of capillary waves, binary droplet collisions, and bubble flows. In capillary waves, the angular frequencies of the oscillation of an ellipsoidal droplet are obtained in good agreement with theoretical ones. In the simulations of binary droplet collisions, coalescence collision and two different types of separating collisions, namely reflexive and stretching separations, can be simulated, and the boundaries of the three types of collisions are in good agreement with an available theoretical prediction. In the bubble flows, the effect of mobility on the coalescence of two rising bubbles is investigated. The behavior of many bubbles in a square duct is also simulated.
Rare-earth intermetallic compounds exhibit rich phenomena induced by the interplay between localized f orbitals and conduction electrons. However, since the energy scale of the crystal-electric-field ...splitting is only a few millielectronvolts, the nature of the mobile electrons accompanied by collective crystal-electric-field excitations has not been unveiled. Here, we examine the low-energy electronic structures of CeSb through the anomalous magnetostructural transitions below the Néel temperature, ~17 K, termed the 'devil's staircase', using laser angle-resolved photoemission, Raman and neutron scattering spectroscopies. We report another type of electron-boson coupling between mobile electrons and quadrupole crystal-electric-field excitations of the 4f orbitals, which renormalizes the Sb 5p band prominently, yielding a kink at a very low energy (~7 meV). This coupling strength is strong and exhibits anomalous step-like enhancement during the devil's staircase transition, unveiling a new type of quasiparticle, named the 'multipole polaron', comprising a mobile electron dressed with a cloud of the quadrupole crystal-electric-field polarization.
We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, ...including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.
To identify oncogenes in leukemias, we performed large-scale resequencing of the leukemia genome using DNA sequence arrays that determine approximately 9 Mbp of sequence corresponding to the exons or ...exon-intron boundaries of 5648 protein-coding genes. Hybridization of genomic DNA from CD34-positive blasts of acute myeloid leukemia (n=19) or myeloproliferative disorder (n=1) with the arrays identified 9148 nonsynonymous nucleotide changes. Subsequent analysis showed that most of these changes were also present in the genomic DNA of the paired controls, with 11 somatic changes identified only in the leukemic blasts. One of these latter changes results in a Met-to-Ile substitution at amino-acid position 511 of Janus kinase 3 (JAK3), and the JAK3(M511I) protein exhibited transforming potential both in vitro and in vivo. Further screening for JAK3 mutations showed novel and known transforming changes in a total of 9 out of 286 cases of leukemia. Our experiments also showed a somatic change responsible for an Arg-to-His substitution at amino-acid position 882 of DNA methyltransferase 3A, which resulted in a loss of DNA methylation activity of >50%. Our data have thus shown a unique profile of gene mutations in human leukemia.
Ni-coated SiC chips and Cu substrates were joined by a paste of Cu nanoparticles and eutectic Sn–Bi powders as an alternative joint to conventional solders. The first thermal treatment of the joint ...was performed to melt eutectic Sn–Bi powders, while the second thermal treatment was conducted at 623 K for 5 min to eliminate the organic molecules around the Cu nanoparticles. The influence of the first thermal treatment conditions (423–473 K for 2–20 min) on the joint structure and strength was investigated. During the first thermal treatment conducted at 423 K for 20 min, or at 473 K for 2 min, Sn–Bi did not migrate to the nanoparticle area. During the second thermal treatment, Bi liquefied, migrated out of the powder, and segregated at the joint interfaces. This resulted in the formation of brittle interfaces and consequently a low bonding strength. In contrast, when the first thermal treatment was performed at 448 K for 20 min or 473 K for more than 5 min, liquefied Sn–Bi migrated out of the powder and segregated at the joint interfaces, where Bi subsequently reacted with the Ni layer at the interface to form Bi
x
Ni
y
intermetallic compounds, which prevented the formation of a brittle interface and thus improved the bonding strength.
New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from (2)H, (3)He, (4)He, (9)Be and (12)C for 0.3 < x < 0.9, Q(2) approximately 3-6 GeV(2). These data ...represent the first measurement of the EMC effect for (3)He at large x and a significant improvement for (4)He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.
We report 75As NMR experiments in heavily electron-doped LaFePnO0.75H0.25 (Pn=As1−xSbx and As1−x′Px′) compounds with the maximum Tcmax(∼33.1K), and compare with the previous results in lightly ...electron-doped LaFePn(O,F) compounds. The Tc of this series can be sensitively controlled by the pnictogen height (hPn) through the substitution at Pn site, and the electron doping level through the substitution at the O site with H or F. In heavily electron-doped LaFePnO(La1111) compounds, we found that spin fluctuations at low-energies were moderately suppressed upon cooling in the Sb-substituted high Tc compounds with high hPn (x ≥ 0), although they are completely suppressed in P-substituted non-superconducting compounds (x′ ≥ 0.2) with lower hPn. This feature is largely different from that in the lightly doped La1111 compounds with the well-nested Fermi surfaces, where the spin fluctuations are critically enhanced upon cooling. Here, we present the characteristics of spin fluctuations over wide doping region of La1111-based compounds, and discuss the relationship with the superconductivity.
Abstract
We report NMR experiments on heavily electron-doped Fe-based superconductor in comparison with the results on the parent Fe-based compounds. The typical parent Fe-based compound LaFe(As
1-
x
...′
P
x
′
)O exhibits the re-emergent antiferromagnetic (AFM) order at
x
′ ~ 0.6 (AFM2) separated from the parent AFM order at
x
′ =0 (AFM1). Systematic
31
P-NMR study on Sr
4
Sc
2
O
6
Fe
2
(As
1−
x
P
x
)
2
(SrSc42622), which has local lattice parameters of iron-pnictogen (Fe
Pn
) layer similar to the series of LaFe(As
1−
x
′
/P
x
′
)O, also revealed that the presence of AFM1 order is universal for most of parent Fe-based compounds. In contrast, the static AFM2 order was absent in this series, however, the dynamical low-energy AFM spin fluctuations are enhanced at around
x
~ 0.8, indicating that the onset of the static AFM2 is quite sensitive to the local lattice parameters of Fe
Pn
layer. In order to elucidate the further universality and diversity, we have carried out
77
Se-NMR measurement on Li
x
(NH
3
)
y
Fe
2−
δ
Se
2
(
T
c
= 44 K) in heavily electron-doped regime. Although the spin fluctuations at low energies does not significantly develops upon cooling, the moderate spin fluctuations were extracted at high temperatures from comparison of the temperature (
T
) dependences of Knight shift and nuclear relaxation rate (1/
T
1
T
). We discuss the universality and diversity of the relationship between the
T
c
and the characteristics of the spin fluctuations in the Fe-based compounds from a microscopic point of the NMR measurements.
The effects of high-temperature aging on a novel hybrid bonding layer were investigated. The hybrid layer, which consisted of Cu nanoparticles and a eutectic Bi-Sn solder powder, was formed by a ...sintering reaction of the solid-phase Cu nanoparticles and a chemical reaction involving the liquid-phase Bi and Sn in combination. The layer was used to bond a SiC chip to a direct bonded aluminum substrate. A conventional Cu nanoparticle-based bonding layer was also prepared as a reference. Samples with these bonding layers were evaluated using the thermal aging test (225 or 250°C, 100h). Bonding strength and synchrotron radiation computed laminography (SRCL) measurements were performed both before and after the thermal aging test. It was observed that thermal aging greatly decreased the bonding strength of the conventional layer. In contrast, the bonding strength of the hybrid layer was reduced only slightly by the thermal aging treatment. SRCL images showed that the conventional layer exhibited numerous cracks, which acted as passages for oxidation. On the other hand, in the hybrid layer, the liquid-phase Bi and Sn densified the Cu sintering phase through the formation of an alloyed Cu-Sn phase. As a result, the hybrid layer contained fewer passages for oxidation as compared to the conventional layer and maintained its bonding strength even against thermal aging. Therefore, the hybrid layer, which is highly stable against thermal aging, will be useful for the high-temperature operation of intelligent power modules.
•Effects of thermal aging on Cu nanoparticle/Bi-Sn hybrid bonding were investigated.•Liquid-phase Bi and Sn densify bonding layer during sintering.•Bonding layer contains few passages for oxidation.•Thermal aging has little effect on bonding strength.
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