50 research outputs found
Multi-Particle Tunneling Transport at Strongly-Correlated Interfaces
We elucidate the multi-particle transport of pair- and spin-tunnelings in
strongly correlated interfaces. Not only usual single-particle tunneling but
also interaction-induced multi-particle tunneling processes naturally arise
from a conventional microscopic model without any empirical parameters, through
the overlap of the many-body wave functions around the interface. We
demonstrate how anomalous tunneling currents occur in a strongly interacting
system due to the pair-tunneling process which we derived microscopically. Our
formulation is useful for junction systems in various disciplines, including
atomtronics, spintronics, and nuclear reactions.Comment: 9 pages, 2 figure
Spin transport between polarized Fermi gases near the ferromagnetic phase transition
We theoretically study the spin current between two polarized Fermi gases
with repulsive interactions near the itinerant ferromagnetic phase transition.
We consider a two-terminal model where the left reservoir is fixed to be fully
polarized while the polarization of the right reservoir is tuned through a
fictitious magnetic field defined by the chemical-potential difference between
different atomic hyperfine states. We calculate the spectra of the spin-flip
susceptibility function, which displays a magnon dispersion emerging from the
Stoner continuum at low momentum in the ferromagnetic phase. Based on the
spin-flip susceptibility and using Keldysh Green's function formalism, we
investigate the spin current induced by quasiparticle and spin-flip tunneling
processes, respectively, and show their dependence on the polarization bias
between two reservoirs. The one-body (quasiparticle) tunneling demonstrates a
linear dependence with respect to the polarization bias. In contrast, the
spin-flip process manifests a predominantly cubic dependence on the bias. While
indicating an enhanced magnon tunneling in the strong-coupling regime, our
results also demonstrate a characteristic behavior around the critical
repulsive strength for ferromagnetic phase transition at low temperatures.Comment: 9 pages, 6 figure
Exploring Superfluid in Dilute Spin-Polarized Neutron Matter
We explore the theoretical possibility of neutron superfluid in
dilute spin-polarized neutron matter, which may be relevant to the crust region
of a magnetized neutron star. In such a dilute regime where the neutron Fermi
energy is less than 1 MeV, the neutron superfluid can be suppressed by
a strong magnetic field of the compact star. In the low-energy limit relevant
for dilute neutron matter, the interaction is stronger than the
one which is believed to induce the triplet superfluid in the core. We present
the ground-state phase diagram of dilute neutron matter with respect to the
magnetic field and numerically estimate the critical temperature of the
neutron superfluid, which is found to exceed K.Comment: 6 pages, 3 figure
First measurements of p11B fusion in a magnetically confined plasma
Proton-boron (p11B) fusion is an attractive potential energy source but technically challenging to implement. Developing techniques to realize its potential requires first developing the experimental capability to produce p11B fusion in the magnetically-confined, thermonuclear plasma environment. Here we report clear experimental measurements supported by simulation of p11B fusion with high-energy neutral beams and boron powder injection in a high-temperature fusion plasma (the Large Helical Device) that have resulted in diagnostically significant levels of alpha particle emission. The injection of boron powder into the plasma edge results in boron accumulation in the core. Three 2 MW, 160 kV hydrogen neutral beam injectors create a large population of well-confined, high -energy protons to react with the boron plasma. The fusion products, MeV alpha particles, are measured with a custom designed particle detector which gives a fusion rate in very good relative agreement with calculations of the global rate. This is the first such realization of p11B fusion in a magnetically confined plasma
Purification of an Antiviral Substance Produced by Alteromonas sp. and Its Virucidal Activity against Fish Viruses
An antiviral substance of a high molecular weight, low cytotoxity and potent virucidal activity was purified from the culture supernatant of a marine Alteromonas sp. 48HS-27. Maximum production of this antiviral substance by the strain in MCYG broth was attained by 72 h-incubation at 25℃. By the purification procedure involving ultrafiltration, precipitation with ammonium sulfate and acetone, gel filtration and native-polyacrylamide gel electrophoresis (PAGE), a polypeptide (48HS-27A) with antiviral activity was obtained at a 270-fold purification with 6.20% yield from the culture supernatant. Molecular weight of the purified 48HS-27A was estimated as approximately 52kDa by both native and sodium dodecyl sulfate (SDS) PAGE. The 50% infection inhibitory concentrations of this substance were from 0.09 to 2.51 μg/ml against one herpesvirus and five rhabdoviruses, whereas the minimal cytotoxic concentration of the substance was 144μg/ml against FHM and CHSE-214 cells. The purified 48HS-27A had proteolytic activity against casein and bovine serum albumin
Electrochemical stability of self-assembled monolayers on nanoporous Au.
Desorption of thiolate self-assembled monolayers (SAMs) seriously limits the fabrication of thiol-based devices. Here we demonstrate that nanoporous Au produced by dealloying Au-Ag alloys exhibits high electrochemical stability against thiolate desorption. Nanoporous Au has many defective sites, lattice strain and residual Ag on the ligament surface. First-principles calculations indicate that these surface aspects increase the binding energy between a SAM and the surface of nanoporous Au