77,469 research outputs found
In situ transmission electron microscopy study on the epitaxial growth of CoSi2 on Si(111) at temperatures below 150 °C
We report an in situ transmission electron microscopy study on the epitaxial growth of CoSi2 on Si(111) from a 10-nm-thick amorphous mixture of Co and Si in the ratio 1:2 which was formed by codeposition of Co and Si near room temperature. Nuclei of CoSi2 are observed in the as-deposited film. These nuclei are epitaxial and extend through the whole film thickness. Upon annealing, these columnar epitaxial CoSi2 grains grow laterally at temperatures as low as 50 °C. The kinetics of this lateral epitaxial growth was studied at temperatures between 50 and 150 °C. The activation energy of the growth process is 0.8±0.1 eV
Axisymmetric Dynamic Response of Spherical and Cylindrical Shells
Axisymmetric dynamic response of spherical and cylindrical shell
Intrinsic Josephson Effects in the Magnetic Superconductor RuSr2GdCu2O8
We have measured interlayer current transport in small sized RuSr2GdCu2O8
single crystals. We find a clear intrinsic Josephson effect showing that the
material acts as a natural
superconductor-insulator-ferromagnet-insulator-superconductor superlattice. So
far, we detected no unconventional behavior due to the magnetism of the RuO2
layers.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let
Crumpling wires in two dimensions
An energy-minimal simulation is proposed to study the patterns and mechanical
properties of elastically crumpled wires in two dimensions. We varied the
bending rigidity and stretching modulus to measure the energy allocation,
size-mass exponent, and the stiffness exponent. The mass exponent is shown to
be universal at value . We also found that the stiffness exponent
is universal, but varies with the plasticity parameters and
. These numerical findings agree excellently with the experimental
results
Cross sections for pentaquark baryon production from protons in reactions induced by hadrons and photons
Using hadronic Lagrangians that include the interaction of pentaquark
baryon with and , we evaluate the cross sections for its
production from meson-proton, proton-proton, and photon-proton reactions near
threshold. With empirical coupling constants and form factors, the predicted
cross sections are about 1.5 mb in kaon-proton reactions, 0.1 mb in rho-nucleon
reactions, 0.05 mb in pion-nucleon reactions, 20 b in proton-proton
reactions, and 40 nb in photon-proton reactions.Comment: 14 pages, 7 figure
Mixing and transient interface condensation of a liquid hydrogen tank
Experiments were conducted to investigate the effect of axial jet-induced mixing on the pressure reduction of a thermally stratified liquid hydrogen tank. The tank was nearly cylindrical, having a volume of about 0.144 cu m with 0.559 m in diameter and 0.711 m long. A mixer/pump unit, which had a jet nozzle outlet of 0.0221 m in diameter was located 0.178 m from the tank bottom and was installed inside the tank to generate the axial jet mixing and tank fluid circulation. The liquid fill and jet flow rate ranged from 42 to 85 percent (by volume) and 0.409 to 2.43 cu m/hr, respectively. Mixing tests began with the tank pressure ranging from 187.5 to 238.5 kPa at which the thermal stratification results in 4.9 to 6.2 K liquid sub cooling. The mixing time and transient vapor condensation rate at the liquid-vapor interface are determined. Two mixing time correlations, based on the thermal equilibrium and pressure equilibrium, are developed. Both mixing time correlations are expressed as functions of system and buoyancy parameters and compared well with other experimental data. The steady state condensation rate correlation of Sonin et al. based on steam-water data is modified and expressed as a function of jet subcooling. The limited liquid hydrogen data of the present study shows that the modified steady state condensation rate correlation may be used to predict the transient condensation rate in a mixing process if the instantaneous values of jet sub cooling and turbulence intensity at the interface are employed
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
CD4+ T-cell responses to Epstein-Barr virus nuclear antigen EBNA1 in Chinese populations are highly focused on novel C-terminal domain-derived epitopes
Epstein-Barr virus nuclear antigen EBNA1, the one viral protein uniformly expressed in nasopharyngeal carcinoma (NPC), represents a prime target for T-cell-based immunotherapy. However, little is known about the EBNA1 epitopes, particularly CD4 epitopes, presented by HLA alleles in Chinese people, the group at highest risk for NPC. We analyzed the CD4 T-cell responses to EBNA1 in 78 healthy Chinese donors and found marked focusing on a small number of epitopes in the EBNA1 C-terminal region, including a DP5- restricted epitope that was recognized by almost half of the donors tested and elicited responses able to recognize EBNA1-expressing, DP5-positive target cells
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