15,581 research outputs found
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A New Layer Casting System for Ceramic Laser Rapid Prototyping Apparatus
In the existing Ceramic Laser Fusion system, slurry is fed on the high
temperature surface of the green part; therefore, a part of water infiltrates into the
green block and vaporizes before the process of layer casting. As a result, the slurry
viscosity rises gradually; the quality of the layer surface is not uniform, and the green
part density is uneven. The aim of present study is to develop a new layer casting
system which can solve the problems mentioned above to obtain a green part with
uniform surface quality and density, and to shorten the time-taken of part fabrication.
The first part of the paper illustrates the major requirements and parameters of a slurry
distributor; the second part describes the integration of the slurry feeding device and
layer casting system. The integrated system can feed slurry and cast thin layer
simultaneously; consequently, the drawbacks of the existing system can be eliminated
and the time-taken of the layer casting can be shortened. A variable-frequency drive
(inverter) is used to control the motor speed. The relation between the frequency and
the slurry delivery can be included in the process control program to adjust the
quantity in accordance with the layer thickness; hence, the waste of the slurry can be
reduced.Mechanical Engineerin
Two-dimensional quasineutral description of particles and fields above discrete auroral arcs
Stationary hot and cool particle distributions in the auroral magnetosphere are modelled using adiabatic assumptions of particle motion in the presence of broad-scale electrostatic potential structure. The study has identified geometrical restrictions on the type of broadscale potential structure which can be supported by a multispecies plasma having specified sources and energies. Without energization of cool thermal ionospheric electrons, a substantial parallel potential drop cannot be supported down to altitudes of 2000 km or less. Observed upward-directed field-aligned currents must be closed by return currents along field lines which support little net potential drop. In such regions the plasma density appears significantly enhanced. Model details agree well with recent broad-scale implications of satellite observations
On the structures and mapping of auroral electrostatic potentials
The mapping of magnetospheric and ionospheric electric fields in a kinetic model of magnetospheric-ionospheric electrodynamic coupling proposed for the aurora is examined. One feature is the generalization of the kinetic current-potential relationship to the return current region (identified as a region where the parallel drop from magnetosphere to ionosphere is positive); such a return current always exists unless the ionosphere is electrically charged to grossly unphysical values. A coherent phenomenological picture of both the low energy return current and the high energy precipitation of an inverted-V is given. The mapping between magnetospheric and ionospheric electric fields is phrased in terms of a Green's function which acts as a filter, emphasizing magnetospheric latitudinal spatial scales of order (when mapped to the ionosphere) 50 to 150 km. This same length, when multiplied by electric fields just above the ionosphere, sets the scale for potential drops between the ionosphere and equatorial magnetosphere
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The Characteristics and Applications of Ceramic Laser Fusion and Ceramic Laser Sintering
The aim of present study is to investigate the possible application of the ceramic parts
which are fabricated with the process of Ceramic Laser Fusion or Ceramic Laser Sintering.
The experimental results reveal: (1) CLF can lead to a reduction in the porosity of the
ceramic part but also can induce micro-cracks. Therefore, this process cannot produce a part
with the required strength by a post-process of infiltration; (2) CLS is capable of fabricating a
ceramic part with high porosity. By adjusting the slurry formulation and varying the scanning
energy, the open porosity can be over 90vol% of the total porosity. After a post-process of
infiltration, the density can be increased to 95%; therefore, CLS can apply to produce a part
with high strength. Because the high open porosity leads to a good permeability, the process
of CLS is suitable for the fabrication of ceramic shell mold.Mechanical Engineerin
Quenched chiral logarithms in lattice QCD with exact chiral symmetry
We examine quenched chiral logarithms in lattice QCD with overlap Dirac
quark. For 100 gauge configurations generated with the Wilson gauge action at on the lattice, we compute quenched quark
propagators for 12 bare quark masses. The pion decay constant is extracted from
the pion propagator, and from which the lattice spacing is determined to be
0.147 fm. The presence of quenched chiral logarithm in the pion mass is
confirmed, and its coefficient is determined to be , in agreement with the theoretical estimate in quenched chiral perturbation
theory. Further, we obtain the topological susceptibility of these 100 gauge
configurations by measuring the index of the overlap Dirac operator. Using a
formula due to exact chiral symmetry, we obtain the mass in quenched
chiral perturbation theory, Mev, and an estimate
of , which is in good agreement with that
determined from the pion mass.Comment: 24 pages, 6 EPS figures; v2: some clarifications added, to appear in
Physical Review
Dissociation of mitochondrial depolarization from cytochrome c release during apoptosis induced by photodynamic therapy
Photodynamic therapy (PDT) with the phthalocyanine photosensitizer Pc 4 induces rapid apoptosis in mouse lymphoma (LY-R) cells, initiating with the release of cytochrome c from mitochondria. It has been proposed that the opening of the mitochondrial membrane permeability transition pores, which results in the dissipation of the mitochondrial membrane potential (Δψm), is essential for the escape of cytochrome c from mitochondria into the cytosol as well as for apoptotic cell death. Therefore, we have assessed the correlation between the loss of Δψm and the release of cytochrome c following PDT. Treatment of LY-R cells with 300 nM Pc 4 and 60, 90 or 120 mJ/cm2of red light resulted in apoptosis of 80–90% of the cells, accompanied by >20-fold elevation in caspase-3-like activity within one h. At all 3 doses of PDT employed here, the majority of the cytochrome c was released from mitochondria at 15 min after irradiation, as determined by an immunohistochemical method. In contrast, the loss of Δψm following PDT, as monitored by the uptake of JC-1 or Rh-123, depended on the PDT dose and the post-treatment time. In spite of the release of cytochrome c at 15 min after each of the 3 doses, a corresponding loss of Δψm was observed only for those cells that received the highest dose of PDT. Virtually all cells that received one of the lower doses of PDT (300 nM Pc 4 plus 60 or 90 mJ/cm2) maintained normal Δψm. Hence, our results support the conclusion that the release of cytochrome c from mitochondria resulting from Pc 4-PDT-induced photodamage is independent of the loss of Δψm. Therefore, it is important to consider a range of doses of this or other apoptotic stimuli in deciphering the relationship of metabolic responses that contribute to apoptosis. © 2001 Cancer Research Campaign http://www.bjcancer.co
Draft Genome Sequence of Mycobacterium arupense Strain GUC1.
We report the draft genome sequence of Mycobacterium arupense strain GUC1 from a sputum sample of a patient with bronchiectasis. This is the first draft genome sequence of Mycobacterium arupense, a rapidly growing nonchromogenic mycobacteria
Draft Genome Sequence of Mycobacterium elephantis Strain Lipa.
We report the draft genome sequence of Mycobacterium elephantis strain Lipa from a sputum sample of a patient with pulmonary disease. This is the first draft genome sequence of M. elephantis, a rapidly growing mycobacterium
Draft Genome Sequence of Mycobacterium obuense Strain UC1, Isolated from Patient Sputum.
We report the draft genome sequence of Mycobacterium obuense strain UC1 from a patient sputum sample. This is the first draft genome sequence of Mycobacterium obuense, a rapidly growing scotochromogenic mycobacterium
Demonstration of the asymmetric lateral Casimir force between corrugated surfaces in the nonadditive regime
The measurement of the lateral Casimir force between two aligned sinusoidally
corrugated Au-coated surfaces has been performed in the nonadditive regime. The
use of deeper corrugations also allowed to demonstrate an asymmetry in the
phase dependences of the lateral Casimir force, as predicted earlier. The
measurement data are found to be in excellent agreement with the exact
theoretical results computed at T=300 K including effect of real material
properties. The deviations between the exact theory and the proximity force
approximation are quantified. The obtained results are topical for applications
in nanomachines.Comment: 9 pages, 3 figure
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