2,610 research outputs found
Relativistic mean-field approximation with density-dependent screening meson masses in nuclear matter
The Debye screening masses of the , and neutral
mesons and the photon are calculated in the relativistic mean-field
approximation. As the density of the nucleon increases, all the screening
masses of mesons increase. It shows a different result with Brown-Rho scaling,
which implies a reduction in the mass of all the mesons in the nuclear matter
except the pion. Replacing the masses of the mesons with their corresponding
screening masses in Walecka-1 model, five saturation properties of the nuclear
matter are fixed reasonably, and then a density-dependent relativistic
mean-field model is proposed without introducing the non-linear self-coupling
terms of mesons.Comment: 14 pages, 3 figures, REVTEX4, Accepted for publication in Int. J.
Mod. Phys.
Ruthenium atomically dispersed in carbon outperforms platinum toward hydrogen evolution in alkaline media.
Hydrogen evolution reaction is an important process in electrochemical energy technologies. Herein, ruthenium and nitrogen codoped carbon nanowires are prepared as effective hydrogen evolution catalysts. The catalytic performance is markedly better than that of commercial platinum catalyst, with an overpotential of only -12 mV to reach the current density of 10 mV cm-2 in 1 M KOH and -47 mV in 0.1 M KOH. Comparisons with control experiments suggest that the remarkable activity is mainly ascribed to individual ruthenium atoms embedded within the carbon matrix, with minimal contributions from ruthenium nanoparticles. Consistent results are obtained in first-principles calculations, where RuCxNy moieties are found to show a much lower hydrogen binding energy than ruthenium nanoparticles, and a lower kinetic barrier for water dissociation than platinum. Among these, RuC2N2 stands out as the most active catalytic center, where both ruthenium and adjacent carbon atoms are the possible active sites
Nuclear superfluidity for antimagnetic rotation in Cd and Cd
The effect of nuclear superfluidity on antimagnetic rotation bands in
Cd and Cd are investigated by the cranked shell model with the
pairing correlations and the blocking effects treated by a particle-number
conserving method. The experimental moments of inertia and the reduced
transition values are excellently reproduced. The nuclear superfluidity is
essential to reproduce the experimental moments of inertia. The two-shears-like
mechanism for the antimagnetic rotation is investigated by examining the shears
angle, i.e., the closing of the two proton hole angular momenta, and its
sensitive dependence on the nuclear superfluidity is revealed.Comment: 14 pages, 4 figure
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