3,613 research outputs found
Enhanced mechanical, thermal and flame retardant properties by combining graphene nanosheets and metal hydroxide nanorods for Acrylonitrile–Butadiene–Styrene copolymer composite
Three metal hydroxide nanorods (MHR) with uniform diameters were synthesized, and then combined with graphene nanosheets (GNS) to prepare acrylonitrile–butadiene–styrene (ABS) copolymer composites. An excellent dispersion of exfoliated two-dimensional (2-D) GNS and 1-D MHR in the ABS matrix was achieved. The effects of combined GNS and MHR on the mechanical, thermal and flame retardant properties of the ABS composites were investigated. With the addition of 2 wt% GNS and 4 wt% Co(OH)2, the tensile strength, bending strength and storage modulus of the ABS composites were increased by 45.1%, 40.5% and 42.3% respectively. The ABS/GNS/Co(OH)2 ternary composite shows the lowest maximum weight loss rate and highest residue yield. Noticeable reduction in the flammability was achieved with the addition of GNS and Co(OH)2, due to the formation of more continuous and compact charred layers that retarded the mass and heat transfer between the flame and the polymer matrix
Nuclear symmetry potential in the relativistic impulse approximation
Using the relativistic impulse approximation with the Love-Franey \textsl{NN}
scattering amplitude developed by Murdock and Horowitz, we investigate the
low-energy (100 MeV MeV) behavior of the nucleon
Dirac optical potential, the Schr\"{o}dinger-equivalent potential, and the
nuclear symmetry potential in isospin asymmetric nuclear matter. We find that
the nuclear symmetry potential at fixed baryon density decreases with
increasing nucleon energy. In particular, the nuclear symmetry potential at
saturation density changes from positive to negative values at nucleon kinetic
energy of about 200 MeV. Furthermore,the obtained energy and density dependence
of the nuclear symmetry potential is consistent with those of the isospin- and
momentum-dependent MDI interaction with , which has been found to describe
reasonably both the isospin diffusion data from heavy-ion collisions and the
empirical neutron-skin thickness of Pb.Comment: 8 pages, 5 figures, revised version to appear in PR
Precise Measurement of Gravity Variations During a Total Solar Eclipse
The variations of gravity were measured with a high precision LaCoste-Romberg
D gravimeter during a total solar eclipse to investigate the effect of solar
eclipse on the gravitational field. The observed anomaly m/s during the eclipse implies that there may be a shielding
property of gravitation
Hidden itinerant-spin phase in heavily-overdoped La2-xSrxCuO4 revealed by dilute Fe doping: A combined neutron scattering and angle-resolved photoemission study
We demonstrated experimentally a direct way to probe a hidden propensity to
the formation of spin density wave (SDW) in a non-magnetic metal with strong
Fermi surface nesting. Substituting Fe for a tiny amount of Cu (1%) induced an
incommensurate magnetic order below 20 K in heavily-overdoped La2-xSrxCuO4
(LSCO). Elastic neutron scattering suggested that this order cannot be ascribed
to the localized spins on Cu or doped Fe. Angle-resolved photoemission
spectroscopy (ARPES), combined with numerical calculations, revealed a strong
Fermi surface nesting inherent in the pristine LSCO that likely drives this
order. The heavily-overdoped Fe-doped LSCO thus represents the first plausible
example of the long-sought "itinerant-spin extreme" of cuprates, where the
spins of itinerant doped holes define the magnetic ordering ground state. This
finding complements the current picture of cuprate spin physics that highlights
the predominant role of localized spins at lower dopings. The demonstrated set
of methods could potentially apply to studying hidden density-wave
instabilities of other "nested" materials on the verge of density wave
ordering.Comment: Abstract and discussion revised; to appear in Phys. Rev. Let
Geometrical structure effect on localization length of carbon nanotubes
The localization length and density of states of carbon nanotubes are
evaluated within the tight-binding approximation. By comparison with the
corresponding results for the square lattice tubes, it is found that the
hexagonal structure affects strongly the behaviors of the density of states and
localization lengths of carbon nanotubes.Comment: 7 pages, 4 figures, revised version to appear in Chin. Phys. Lett.
The title is changed. Some arguments are adde
Role of the domain encompassing Arg304–Ile328 in rat P2X2 receptor conformation revealed by alterations in complex glycosylation at Asn298
The final 25 amino acids of the ectodomain of the P2X receptors, immediately prior to the second TM (transmembrane domain) (pre-TM2: Arg304–Ile328 in rat P2X2), are highly conserved. Whole-cell patch clamp recordings showed that single cysteine substitutions in the N-terminal half of pre-TM2 (Arg304–Ile314) led to loss of function at Arg304, Leu306, Lys308 and Ile312. Cysteine substitutions within this region also resulted in a significant reduction in the apparent molecular mass of receptors, due to loss of complex glycosylation at the nearby acceptor site Asn298, which was not seen for the C-terminal portion of pre-TM2 (Asp315–Ile328). The reduction in complex glycosylation was not due to reduced cell-surface presentation, demonstrating that glycosylation at Asn298 was acting as a sensor of subtle changes in receptor conformation within the pre-TM2 region. When this N-glycan site was repositioned closer to the plasma membrane by mutagenesis (N298S together with G299N, T300N, T301N or T303N), glycosylation was restored at G299N and T300N, but was impaired for T301N and completely absent for T303N. These results suggest that the region in the vicinity of Asp315 is at the plasma membrane interface and that the N-terminal portion of pre-TM2 (Arg304–Ile314) is important for the correct conformation of the receptor at the extracellular face of the membrane
Testing Technicolor Models in Top Quark Pair Production at High Energy Photon Colliders
We study pseudo-Goldstone boson corrections to top quark pair production
rates in technicolor models with and without topcolor at the E=0.5 teV and 1.5
TeV photon colliders. We find that, for reasonable ranges of the parameters,
the corrections are large enough to be observable, and the corrections in
models with topcolor are considerably larger than those in models without
topcolor, and they are all significantly larger than the corresponding
corrections in the minimal supersymmetric standard model (MSSM) with tan(beta)
of the order of 1. So that the two kinds of technicolor models and the MSSM
with tan(beta) of the order of 1 can be experimentally distinguished.Comment: Version for publication in Phys.Rev.D with some references and
discussions added and some typos correcte
Abelian Chern-Simons field theory and anyon equation on a torus
We quantize the abelian Chern-Simons theory coupled to non-relativistic
matter field on a torus without invoking the flux quantization. Through a
series of canonical transformations which is equivalent to solving the Gauss
constraint, we obtain an effective hamiltonian density with periodic matter
field. We also obtain the many-anyon Schr\"odinger equation with periodic
Aharonov-Bohm potentials and analyze the periodic property of the wavefunction.
Some comments are given on the different features of our approach from the
previous ones.Comment: 24, SNUTP-93-9
Aortic bypass and orthotopic right renal autotransplantation for midaortic syndrome: a case report
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