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