30,738 research outputs found
Chirality Selection in Open Flow Systems and in Polymerization
As an attempt to understand the homochirality of organic molecules in life, a
chemical reaction model is proposed where the production of chiral monomers
from achiral substrate is catalyzed by the polymers of the same enatiomeric
type. This system has to be open because in a closed system the enhanced
production of chiral monomers by enzymes is compensated by the associated
enhancement in back reaction, and the chiral symmetry is conserved. Open flow
without cross inhibition is shown to lead to the chirality selection in a
general model. In polymerization, the influx of substrate from the ambience and
the efflux of chiral products for purposes other than the catalyst production
make the system necessarily open. The chiral symmetry is found to be broken if
the influx of substrate lies within a finite interval. As the efficiency of the
enzyme increases, the maximum value of the enantiomeric excess approaches unity
so that the chirality selection becomes complete.Comment: 8 pages, 4 figure
Case of Almost Redundant Components in 3 alpha Faddeev Equations
The 3 alpha orthogonality condition model using the Pauli-forbidden bound
states of the Buck, Friedlich and Wheatly alpha alpha potential can yield a
compact 3 alpha ground state with a large binding energy, in which a small
admixture of the redundant components can never be eliminated.Comment: Revtex V4.0, 4 pages, no figure
Dewetting of a solid monolayer
We report on the dewetting of a monolayer on a solid substrate, where mass
transport occurs via surface diffusion. For a wide range of parameters, a
labyrinthine pattern of bilayer islands is formed. An irreversible regime and a
thermodynamic regime are identified. In both regimes, the velocity of a
dewetting front, the wavelength of the bilayer island pattern, and the rate of
nucleation of dewetted zones are obtained. We also point out the existence of a
scaling behavior, which is analyzed by means of a geometrical model.Comment: to be published in PhysRevLet
Microscopic observation of superconducting fluctuations in -(BEDT-TTF)Cu[N(CN)]Br by C NMR spectroscopy
We performed C-NMR experiment and measured spin-lattice relaxation
rate divided by temperature near the superconducting (SC) transition
temperature in -(BEDT-TTF)Cu[N(CN)]Br (-Br
salt), and -(BEDT-TTF)Cu(NCS) (-NCS salt). We
observed the reduction of starting at the temperature higher than
in -Br salt. Microscopic observation of quasi-particle density of
states in the fluctuating SC state revealed the effects of short-range Cooper
pairs induced in the normal state to the quasi-particle density of states. We
also performed systematic measurements in the fields both parallel and
perpendicular to the conduction plane in -Br and -NCS salts,
and confirmed that the reduction of above is observed only
in -Br salt regardless of the external field orientation.Comment: Accepted for publication in PR
Controlling edge states of zigzag carbon nanotubes by the Aharonov-Bohm flux
It has been known theoretically that localized states exist around zigzag
edges of a graphite ribbon and of a carbon nanotube, whose energy eigenvalues
are located between conduction and valence bands. We found that in metallic
single-walled zigzag carbon nanotubes two of the localized states become
critical, and that their localization length is sensitive to the mean curvature
of a tube and can be controlled by the Aharonov-Bohm flux. The curvature
induced mini-gap closes by the relatively weak magnetic field. Conductance
measurement in the presence of the Aharonov-Bohm flux can give information
about the curvature effect and the critical states.Comment: 5 pages, 4 figure
Spin-dependent Polarizability of Nucleon with Dispersion Relation in the Skyrme Model
We calculate the spin-dependent polarizability of the nucleon in the Skyrme
model. The result is compared with that of a heavy baryon chiral perturbation
theory(HBChPT), and is shown to be the same as that of HBChPT up to the
-pole terms in the narrow width limit of the state and with
the experimental physical constants. The effect of the channel is
rather small and is numerically quite similar to that of the loop in
the HBChPT. The electric and magnetic polarizabilities are recalculated using
the transverse photon and a consistent inclusion of the width.Comment: 11 pages, LaTeX, no figures. misprints correcte
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