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Freeform Bioprinting of Liver Encapsulated in Alginate Hydrogels Tissue Constructs for Pharmacokinetic Study
An in vitro model that can be realistically and inexpensively used to predict human response to
various drug administration and toxic chemical exposure is needed. By fabricating a microscale
3D physiological tissue construct consisting of an array of channels and tissue-embedded
chambers, one can selectively develop various biomimicking mammalian tissues for a number of
pharmaceutical applications, for example, experimental pharmaceutical screening for drug
efficacy and toxicity along with apprehending the disposition and metabolic profile of a
candidate drug. This paper addresses issues relating to the development and implementation of a
bioprinting process for freeform fabrication of a 3D cell-encapsulated hydrogel-based tissue
construct, the direct integration onto a microfluidic device for pharmacokinetic study, and the
underlying engineering science for the fabrication of a 3D microscale tissue chamber as well as
its application in pharmacokinetic study. To this end, a prototype 3D microfluidic tissue chamber
embedded with liver cells encapsulated within a hydrogel matrix construct is bioprinted as a
physiological in vitro model for pharmacokinetic study. The developed fabrication processes are
further validated and parameters optimized by assessing cell viability and liver cell phenotype, in
which metabolic and synthetic liver functions are quantitated.Mechanical Engineerin
Tethered balloon-based measurements of meteorological variables and aerosols
Tethered balloon based measurements of the vertical distributions of temperature, humidity, wind speed, and aerosol concentrations were taken over a 4-hour period beginning at sunrise on June 29, 1976, at Wallops Island, Virginia. Twelve consecutive profiles of each variable were obtained from ground to about 500 meters. These measurements were in conjuction with a noise propagation study on remotely arrayed acoustic range (ROMAAR) at Wallops Flight Center. An organized listing of these vertical soundings is presented. The tethered balloon system configuration utilized for these measurements is described
Damping of antiferromagnetic spin waves by valence fluctuations in the double layer perovskite YBaFe2O5
Inelastic neutron scattering experiments show that spin dynamics in the
charge ordered insulating ground state of the double-layer perovskite YBaFe2O5
is well described in terms of eg superexchange interactions. Above the Verwey
transition at TV = 308 K, t2g double exchange-type conduction within
antiferromagnetic FeO2--BaO--FeO2 double layers proceeds by an electron hopping
process that requires a spin flip of the five-fold coordinated Fe ions, costing
an energy 5S^2 of approximately 0.1 eV. The hopping process disrupts
near-neighbor spin correlations, leading to massive damping of zone-boundary
spin waves.Comment: RevTeX, 4 pages, 4 figures, submitted to Phys. Rev. Let
Larkin-Ovchinnikov-Fulde-Ferrell phase in the superconductor (TMTSF)2ClO4: Theory versus experiment
We consider a formation of the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase
in a quasi-one-dimensional (Q1D) conductor in a magnetic field, parallel to its
conducting chains, where we take into account both the paramagnetic
spin-splitting and orbital destructive effects against superconductivity. We
show that, due to a relative weakness of the orbital effects in a Q1D case, the
LOFF phase appears in (TMTSF)ClO superconductor for real values of its
Q1D band parameters. We compare our theoretical calculations with the recent
experimental data by Y. Maeno's group [S. Yonezawa et al., Phys. Rev. Lett.
\textbf{100}, 117002 (2008)] and show that there is a good qualitative and
quantitative agreement between the theory and experimental data.Comment: 4 pages, 1 figur
The effect of drying on timber frame connections post flooding
Timber structures face a unique risk from flooding. Elevations in moisture content due to prolonged wetting will lead to a reduction in the mechanical properties of the building. Despite recent growth of timber construction in the UK and a known increased risk from flooding, little research has been conducted into its effects on light frame timber construction and the most efficacious drying method. This paper presents the results of experiments to determine the optimum drying conditions for light timber frame construction with oriented strand board sheathing after simulated flooding. A series of specimens were wetted for 5 d to simulate flooding before exposure to different environments. The specimens were load tested and values of ultimate strength, yield strength and stiffness were compared to those of un-wetted control specimens. It was found that the optimum drying condition for recovery of the maximum pre-wetting mechanical properties was an environment of 38°C and 40% relative humidity. Although this is an optimal setting there is still a permanent reduction in the mechanical properties of approximately 40% for strengths and 20% for stiffness. Stiffness is dependent on grain orientation; however, strength was found to be independent of grain orientation, as it is governed by the oriented strand board failure
Field Scanner Design for MUSTANG of the Green Bank Telescope
MUSTANG is a bolometer camera for the Green Bank Telescope (GBT) working at a
frequency of 90 GHz. The detector has a field of view of 40 arcseconds. To
cancel out random emission change from atmosphere and other sources, requires a
fast scanning reflecting system with a few arcminute ranges. In this paper, the
aberrations of an off-axis system are reviewed. The condition for an optimized
system is provided. In an optimized system, as additional image transfer
mirrors are introduced, new aberrations of the off-axis system may be
reintroduced, resulting in a limited field of view. In this paper, different
scanning mirror arrangements for the GBT system are analyzed through the ray
tracing analysis. These include using the subreflector as the scanning mirror,
chopping a flat mirror and transferring image with an ellipse mirror, and
chopping a flat mirror and transferring image with a pair of face-to-face
paraboloid mirrors. The system analysis shows that chopping a flat mirror and
using a well aligned pair of paraboloids can generate the required field of
view for the MUSTUNG detector system, while other systems all suffer from
larger off-axis aberrations added by the system modification. The spot diagrams
of the well aligned pair of paraboloids produced is only about one Airy disk
size within a scanning angle of about 3 arcmin.Comment: 7 pages, 9 figure
Tunable pulse delay and advancement in a coupled nanomechanical resonator-superconducting microwave cavity system
We theoretically study the transmission of a weak probe field under the
influence of a strong pump field in a coupled nanomechanical
resonator-superconducting microwave cavity system. Using the standard
input-output theory, we find that both pulse delay (slow light effect) and
advancement (fast light effect) of the probe field can appear in this coupled
system provided that we choose the suitable detuning of the pump field from
cavity resonance. The magnitude of the delay (advancement) can be tuned
continuously by adjusting the power of the pump field. This technique
demonstrates great potential in applications including microwave phase shifter
and delay line.Comment: 12pages, 3 figure
Dynamical chiral symmetry breaking and a critical mass
On a bounded, measurable domain of non-negative current-quark mass, realistic
models of QCD's gap equation can simultaneously admit two inequivalent
dynamical chiral symmetry breaking (DCSB) solutions and a solution that is
unambiguously connected with the realisation of chiral symmetry in the Wigner
mode. The Wigner solution and one of the DCSB solutions are destabilised by a
current-quark mass and both disappear when that mass exceeds a critical value.
This critical value also bounds the domain on which the surviving DCSB solution
possesses a chiral expansion. This value can therefore be viewed as an upper
bound on the domain within which a perturbative expansion in the current-quark
mass around the chiral limit is uniformly valid for physical quantities. For a
pseudoscalar meson constituted of equal mass current-quarks, it corresponds to
a mass m_{0^-}~0.45GeV. In our discussion we employ properties of the two DCSB
solutions of the gap equation that enable a valid definition of in
the presence of a nonzero current-mass. The behaviour of this condensate
indicates that the essentially dynamical component of chiral symmetry breaking
decreases with increasing current-quark mass.Comment: 9 pages, 7 figures. Minor wording change
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