711 research outputs found
Tuning the electrically evaluated electron Lande g factor in GaAs quantum dots and quantum wells of different well widths
We evaluate the Lande g factor of electrons in quantum dots (QDs) fabricated
from GaAs quantum well (QW) structures of different well width. We first
determine the Lande electron g factor of the QWs through resistive detection of
electron spin resonance and compare it to the enhanced electron g factor
determined from analysis of the magneto-transport. Next, we form laterally
defined quantum dots using these quantum wells and extract the electron g
factor from analysis of the cotunneling and Kondo effect within the quantum
dots. We conclude that the Lande electron g factor of the quantum dot is
primarily governed by the electron g factor of the quantum well suggesting that
well width is an ideal design parameter for g-factor engineering QDs
Influence of the Host Cultivar on Disease and Viral Accumulation Dynamics in Tomato under Mixed Infection with Potato virus X and Tomato mosaic virus
The primary leaves of seedlings of tomato (Lycopersicon esculentum Mill.) cultivar Fukuju No. 2 (a common
Japanese cultivar that is susceptible to Tobacco mosaic virus (TMV, genus Tobamovirus) were inoculated at the
five-true leaf stage with the O strain of Potato virus X (PVX, genus Potexvirus) and with a mixture of that strain plus
Tomato mosaic virus (ToMV, genus Tobamovirus). Inoculation resulted in varying degrees of disease manifestation.
During the acute stage of the resulting severe disease (between 5 and 12 days postinoculation), PVX and ToMV levels
rose considerably in both the inoculated and the systematically infected leaves. Furthermore, levels of PVX in the
systemically infected upper leaves (positions 5 to 7) of plants with a mixed infection were three to six times as high as
in plants given the single infection, as determined by direct double antibody sandwich-enzyme linked immunosorbent
assay (DAS-ELISA). In tomato cv. GCR 236 (+/+), symptom manifestation and the accumulation of both PVX and
ToMV closely followed the pattern recorded for cv. Fukuju No. 2. In cv. GCR 237 (Tm-1) plants, however, only PVX
accumulated while ToMV whether inoculated singly or mixed with PVX was detected neither in the inoculated nor in
the systemically infected leaves even 14 days after inoculation. In contrast to other cultivars, SDS-PAGE, Western
blot and Northern blot hybridization did not reveal any enhancement of the coat protein and genomic RNA of PVX in
such systemically infected leaves. Consequently, the characteristic severe symptoms normally associated with mixed
infection in TMV-susceptible cultivars were absent
Light scattering and phase behavior of Lysozyme-PEG mixtures
Measurements of liquid-liquid phase transition temperatures (cloud points) of
mixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG)
show that the addition of low molecular weight PEG stabilizes the mixture
whereas high molecular weight PEG was destabilizing. We demonstrate that this
behavior is inconsistent with an entropic depletion interaction between
lysozyme and PEG and suggest that an energetic attraction between lysozyme and
PEG is responsible. In order to independently characterize the lysozyme/PEG
interactions, light scattering experiments on the same mixtures were performed
to measure second and third virial coefficients. These measurements indicate
that PEG induces repulsion between lysozyme molecules, contrary to the
depletion prediction. Furthermore, it is shown that third virial terms must be
included in the mixture's free energy in order to qualitatively capture our
cloud point and light scattering data. The light scattering results were
consistent with the cloud point measurements and indicate that attractions do
exist between lysozyme and PEG.Comment: 5 pages, 2 figures, 1 tabl
Tests of mode coupling theory in a simple model for two-component miscible polymer blends
We present molecular dynamics simulations on the structural relaxation of a
simple bead-spring model for polymer blends. The introduction of a different
monomer size induces a large time scale separation for the dynamics of the two
components. Simulation results for a large set of observables probing density
correlations, Rouse modes, and orientations of bond and chain end-to-end
vectors, are analyzed within the framework of the Mode Coupling Theory (MCT).
An unusually large value of the exponent parameter is obtained. This feature
suggests the possibility of an underlying higher-order MCT scenario for dynamic
arrest.Comment: Revised version. Additional figures and citation
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