296,110 research outputs found
Biodegradable Polylactic Acid (PLA) Microstructures for Scaffold Applications
In this research, we present a simple and cost effective soft lithographic
process to fabricate PLA scaffolds for tissue engineering. In which, the
negative photoresist JSR THB-120N was spun on a glass subtract followed by
conventional UV lithographic processes to fabricate the master to cast the PDMS
elastomeric mold. A thin poly(vinyl alcohol) (PVA) layer was used as a mode
release such that the PLA scaffold can be easily peeled off. The PLA precursor
solution was then cast onto the PDMS mold to form the PLA microstructures.
After evaporating the solvent, the PLA microstructures can be easily peeled off
from the PDMS mold. Experimental results show that the desired microvessels
scaffold can be successfully transferred to the biodegradable polymer PLA.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Extraction of nuclear matter properties from nuclear masses by a model of equation of state
The extraction of nuclear matter properties from measured nuclear masses is
investigated in the energy density functional formalism of nuclei. It is shown
that the volume energy and the nuclear incompressibility depend
essentially on , whereas the symmetry energy
and the density symmetry coefficient as well as symmetry incompressibility
depend essentially on , where
, and are the
neutron and proton chemical potentials respectively, the nuclear energy,
and the Coulomb energy. The obtained symmetry energy is ,
while other coefficients are uncertain within ranges depending on the model of
nuclear equation of state.Comment: 12 pages and 7 figure
Effective nucleon-nucleon interactions and nuclear matter equation of state
Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and
Tondeur interactions are written as polynomials of the cubic root of density,
with coefficients that are functions of the relative neutron excess .
In the extrapolation toward states far away from the standard one, it is shown
that the asymmetry dependence of the critical point ()
depends on the model used. However, when the equations of state are fitted to
the same standard state, the value of is almost the same in Skyrme
and in Myers-Swiatecki interactions, while is much lower in Tondeur
interaction. Furthermore, does not depend sensitively on the choice
of the parameter in Skyrme interaction.Comment: 15 pages, 9 figure
Nuclear matter properties and relativistic mean-field theory
Nuclear matter properties are calculated in the relativistic mean field
theory by using a number of different parameter sets. The result shows that the
volume energy and the symmetry energy are around the acceptable
values 16MeV and 30MeV respectively; the incompressibility is
unacceptably high in the linear model, but assumes reasonable value if
nonlinear terms are included; the density symmetry is around for
most parameter sets, and the symmetry incompressibility has positive sign
which is opposite to expectations based on the nonrelativistic model. In almost
all parameter sets there exists a critical point , where
the minimum and the maximum of the equation of state are coincident and the
incompressibility equals zero, falling into ranges
0.014fmfm and ; for a few
parameter sets there is no critical point and the pure neutron matter is
predicted to be bound. The maximum mass of neutron stars is predicted
in the range 2.45MM, the corresponding
neutron star radius is in the range 12.2kmkm.Comment: 10 pages, 5 figure
Energy dependence of Normal Branch Oscillation in Scorpius X-1
We report the energy dependence of normal branch oscillations (NBOs) in
Scorpius X-1, a low-mass X-ray binary Z-source. Three characteristic quantities
(centroid frequency, quality factor, and fractional root-mean-squared (rms)
amplitude) of a quasi-periodic oscillation signal as functions of photon energy
are investigated. We found that, although it is not yet statistically well
established, there is a signature indicating that the NBO centroid frequency
decreases with increasing photon energy when it is below 6-8 keV, which turns
out to be positively correlated with the photon energy at the higher energy
side. In addition, the rms amplitude increases significantly with the photon
energy below 13 keV and then decreases in the energy band of 13-20 keV. There
is no clear dependence on photon energy for the quality factor. Based on these
results, we suggest that the NBO originates mainly in the transition layer.Comment: 6 pages, 4 figure
Single charge sensing and transport in double quantum dots fabricated from commercially grown Si/SiGe heterostructures
We perform quantum Hall measurements on three types of commercially available
modulation doped Si/SiGe heterostructures to determine their suitability for
depletion gate defined quantum dot devices. By adjusting the growth parameters,
we are able to achieve electron gases with charge densities 1-3 X 10^{11}/cm^2
and mobilities in excess of 100,000 cm^2/Vs. Double quantum dot devices
fabricated on these heterostructures show clear evidence of single charge
transitions as measured in dc transport and charge sensing and exhibit electron
temperatures of 100 mK in the single quantum dot regime.Comment: Related papers at http://pettagroup.princeton.ed
The nature of the continuum limit in strongly coupled quenched QED
We review the results of large scale simulations of noncompact quenched
which use spectrum and Equation of State calculations to determine the theory's
phase diagram, critical indices, and continuum limit. The resulting anomalous
dimensions are in good agreement with Schwinger-Dyson solutions of the ladder
graphs of conventional and they satisfy the hyperscaling relations
expected of a relativistic renormalizable field theory. The spectroscopy
results satisfy the constraints of the Goldstone mechanism and PCAC, and may be
indicative of Technicolor versions of the Standard Model which are strongly
coupled at short distances.Comment: (talk given at the XXVI ICHEP, Dallas, TX, Aug 6-12 92), 6 pp.,
ILL-(TH)-92-#2
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