209,586 research outputs found
Suzaku study of gas properties along filaments of A2744
Context: We present the results of Suzaku observations of a massive galaxy
cluster A2744, which is an active merger at . Aims: By using long
X-ray observations of A2744, we aim to understand the growth of the cluster and
the gas heating process through mass accretion along the surrounding filaments.
Methods: We analyzed data from two-pointed Suzaku observations of A2744 to
derive the temperature distribution out to the virial radius in three different
directions. We also performed a deprojection analysis to study radial profiles
of gas temperature, density, and entropy and compared the X-ray results with
multi-wavelength data to investigate correlations with the surface density of
galaxies and with radio relics. Results: The gas temperature was measured out
to the virial radius in the north-east region and to about
in the north-west and south regions. The radial profile of the gas
temperature is rather flat and the temperature is very high (even near
); it is comparable to the mean temperature of this cluster (
keV). These characteristics have not been reported in any other cluster. We
find a hint of temperature jump in the northeast region whose location
coincides with a large radio relic, indicating that the cluster experienced gas
heating because of merger or mass accretion onto the main cluster. The
temperature distribution is anisotropic and shows no clear positive correlation
with the galaxy density, which suggests an inhomogeneous mass structure and a
complex merger history in A2744.Comment: 8 pages, 8 figures, A&A accepte
Phase Diffusion in Single-Walled Carbon Nanotube Josephson Transistors
We investigate electronic transport in Josephson junctions formed by
single-walled carbon nanotubes coupled to superconducting electrodes. We
observe enhanced zero-bias conductance (up to 10e^2/h) and pronounced
sub-harmonic gap structures in differential conductance, which arise from the
multiple Andreev reflections at superconductor/nanotube interfaces. The
voltage-current characteristics of these junctions display abrupt switching
from the supercurrent branch to resistive branch, with a gate-tunable switching
current ranging from 50 pA to 2.3 nA. The finite resistance observed on the
supercurrent branch and the magnitude of the switching current are in good
agreement with calculation based on the model of classical phase diffusion
Wood-Inspired Morphologically Tunable Aligned Hydrogel for High-Performance Flexible All-Solid-State Supercapacitors
Oriented microstructures are widely found in various biological systems for multiple functions. Such anisotropic structures provide low tortuosity and sufficient surface area, desirable for the design of high-performance energy storage devices. Despite significant efforts to develop supercapacitors with aligned morphology, challenges remain due to the predefined pore sizes, limited mechanical flexibility, and low mass loading. Herein, a wood-inspired flexible all-solid-state hydrogel supercapacitor is demonstrated by morphologically tuning the aligned hydrogel matrix toward high electrode-materials loading and high areal capacitance. The highly aligned matrix exhibits broad morphological tunability (47–12 µm), mechanical flexibility (0°–180° bending), and uniform polypyrrole loading up to 7 mm thick matrix. After being assembled into a solid-state supercapacitor, the areal capacitance reaches 831 mF cm−2 for the 12 µm matrix, which is 259% times of the 47 µm matrix and 403% times of nonaligned matrix. The supercapacitor also exhibits a high energy density of 73.8 µWh cm−2, power density of 4960 µW cm−2, capacitance retention of 86.5% after 1000 cycles, and bending stability of 95% after 5000 cycles. The principle to structurally design the oriented matrices for high electrode material loading opens up the possibility for advanced energy storage applications
Stable Heteronuclear Few-Atom Bound States in Mixed Dimensions
We study few-body problems in mixed dimensions with heavy atoms
trapped individually in parallel one-dimensional tubes or two-dimensional
disks, and a single light atom travels freely in three dimensions. By using the
Born-Oppenheimer approximation, we find three- and four-body bound states for a
broad region of heavy-light atom scattering length combinations. Specifically,
the existence of trimer and tetramer states persist to negative scattering
lengths regime, where no two-body bound state is present. These few-body bound
states are analogous to the Efimov states in three dimensions, but are stable
against three-body recombination due to geometric separation. In addition, we
find that the binding energy of the ground trimer and tetramer state reaches
its maximum value when the scattering lengths are comparable to the separation
between the low-dimensional traps. This resonant behavior is a unique feature
for the few-body bound states in mixed dimensions.Comment: Extended version with 14 pages and 14 figure
Determination of a set of constitutive equations for an al-li alloy at SPF conditions
© 2015 The Authors.Uniaxial tensile tests of aluminium-lithium alloy AA1420wereconducted at superplastic forming conditions. The mechanical properties of this Al-Li alloy were then modelled by a set of physicallybased constitutive equations. The constitutive equations describe the isotropic work hardening,recovery and damage by dislocation density changes and grain size evolution. Based on a recent upgraded optimisation technique, the material constants for these constitutive equations were determined
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