12,297 research outputs found
Treatment of Metal Wastes Containing Ni, Co and Mn with Deep-Sea Manganese Nodules
The spent Ni-Cd battery and the spent catalyst containing cobalt were treated by reductionsmelting process with deep-sea Manganese nodules for recovery of nickel and cobalt metals. The nickel in the spent Ni-Cd battery could be recovered with adding 5% coke as a reducing
agent regardless of the amount of battery added. However, to recover cobalt from the spent catalyst, it is required to add more coke for reduction of cobalt oxide in the catalyst. The treatment of metal wastes with manganese nodules can contribute to lower the cost for the proce-ssing of nodules and to facilitate the recycling of metal wastes
Free Energy Approach to the Formation of an Icosahedral Structure during the Freezing of Gold Nanoclusters
The freezing of metal nanoclusters such as gold, silver, and copper exhibits
a novel structural evolution. The formation of the icosahedral (Ih) structure
is dominant despite its energetic metastability. This important phenomenon,
hitherto not understood, is studied by calculating free energies of gold
nanoclusters. The structural transition barriers have been determined by using
the umbrella sampling technique combined with molecular dynamics simulations.
Our calculations show that the formation of Ih gold nanoclusters is attributed
to the lower free energy barrier from the liquid to the Ih phases compared to
the barrier from the liquid to the face-centered-cubic crystal phases
Pairing Reentrance Phenomenon in Heated Rotating Nuclei in the Shell Model Monte Carlo Approach
Rotational motion of heated 72-Ge is studied within the microscopic Shell
Model Monte Carlo approach. We investigate the the angular momentum alignment
and nuclear pairing correlations associated with J-pi Cooper pairs as a
function of the rotational frequency and temperature. The reentrance of pairing
correlations with temperature is predicted at high rotational frequencies. It
manifests itself through the anomalous behavior of specific heat and level
density.Comment: 4 pages; 4 figure
Propagation of Exchange Bias in CoFe/FeMn/CoFe Trilayers
CoFe/FeMn, FeMn/CoFe bilayers and CoFe/FeMn/CoFe trilayers were grown in
magnetic field and at room temperature. The exchange bias field
depends strongly on the order of depositions and is much higher at CoFe/FeMn
than at FeMn/CoFe interfaces. By combining the two bilayer structures into
symmetric CoFe/FeMn()/CoFe trilayers, and
of the top and bottom CoFe layers, respectively, are both enhanced.
Reducing of the trilayers also results in enhancements of
both and . These results evidence the propagation of
exchange bias between the two CoFe/FeMn and FeMn/CoFe interfaces mediated by
the FeMn antiferromagnetic order
Origin of the anomalous long lifetime of 14C
We report the microscopic origins of the anomalously suppressed beta decay of
14C to 14N using the ab initio no-core shell model (NCSM) with the Hamiltonian
from chiral effective field theory (EFT) including three-nucleon force (3NF)
terms. The 3NF induces unexpectedly large cancellations within the p-shell
between contributions to beta decay, which reduce the traditionally large
contributions from the NN interactions by an order of magnitude, leading to the
long lifetime of 14C.Comment: 4 pages, 2 figures and 2 table
SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop
We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He
II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed
with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR)
instrument, also known as FIMS. The spatial distribution of FUV emission
generally corresponds with a limb-brightened shell, and is similar to optical,
radio and X-ray images. The features found in the present work include a
``carrot'', diffuse interior, and breakout features, which have not been seen
in previous FUV studies. Shock velocities of 140-160 km/s is found from a line
ratio of O IV] to O III], which is insensitive not only to resonance scattering
but also to elemental abundance. The estimated velocity indicates that the fast
shocks are widespread across the remnant. By comparing various line ratios with
steady-state shock models, it is also shown that the resonance scattering is
widespread.Comment: 13 pages, 3 figures, 1 table, accepted for publication in ApJ
High-efficiency WSi superconducting nanowire single-photon detectors for quantum state engineering in the near infrared
We report on high-efficiency superconducting nanowire single-photon detectors
based on amorphous WSi and optimized at 1064 nm. At an operating temperature of
1.8 K, we demonstrated a 93% system detection efficiency at this wavelength
with a dark noise of a few counts per second. Combined with cavity-enhanced
spontaneous parametric down-conversion, this fiber-coupled detector enabled us
to generate narrowband single photons with a heralding efficiency greater than
90% and a high spectral brightness of
photons/(smWMHz). Beyond single-photon generation at large rate,
such high-efficiency detectors open the path to efficient multiple-photon
heralding and complex quantum state engineering
- …