858 research outputs found
One-dimensional steady-state thermal model for rotary kilns used in the manufacture of cement
Peer reviewedPostprin
Metal-Insulator Transition and Spin Degree of Freedom in Silicon 2D Electron Systems
Magnetotransport in 2DES's formed in Si-MOSFET's and Si/SiGe quantum wells at
low temperatures is reported. Metallic temperature dependence of resistivity is
observed for the n-Si/SiGe sample even in a parallel magnetic field of 9T,
where the spins of electrons are expected to be polarized completely.
Correlation between the spin polarization and minima in the diagonal
resistivity observed by rotating the samples for various total strength of the
magnetic field is also investigated.Comment: 3 pages, RevTeX, 4 eps-figures, conference paper (EP2DS-13
Comment on "Theory of metal-insulator transitions in gated semiconductors" (B. L. Altshuler and D. L. Maslov, Phys. Rev. Lett. 82, 145 (1999))
In a recent Letter, Altshuler and Maslov propose a model which attributes the
anomalous temperature and field dependence of the resistivity of
two-dimensional electron (or hole) systems to the charging and discharging of
traps in the oxide (spacer), rather than to intrinsic behavior of interacting
particles associated with a conductor-insulator transition in two dimensions.
We argue against this model based on existing experimental evidence.Comment: 1 page; submitted to PR
Deconstruction of the Trap Model for the New Conducting State in 2D
A key prediction of the trap model for the new conducting state in 2D is that
the resistivity turns upwards below some characteristic temperature, . Altshuler, Maslov, and Pudalov have argued that the reason why no upturn
has been observed for the low density conducting samples is that the
temperature was not low enough in the experiments. We show here that within the Altshuler, Maslov, and Pudalov trap model actually increases
with decreasing density, contrary to their claim. Consequently, the trap model
is not consistent with the experimental trends.Comment: Published version of Deconstructio
Interface charged impurity scattering in semiconductor MOSFETs and MODFETs: temperature dependent resistivity and 2D "metallic" behavior
We present the results on the anomalous 2D transport behavior by employing
Drude-Boltzmann transport theory and taking into account the realistic charge
impurity scattering effects. Our results show quantitative agreement with the
existing experimental data in several different systems and address the origin
of the strong and non-monotonic temperature dependent resistivity.Comment: Presented at SIMD, Dec. 1999 in Hawaii. To be published in
Superlattices and Microstructures, May 2000 issu
Cell Adhesion to Crystal Surfaces: A Model for Initial Stages in the Attachment of Cells to Solid Substrates
This study addresses the mechanism of the chirally-restricted, ROD-independent adhesion of A6 epithelial cells to the {011} faces of calcium {R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesion of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediated adhesion to conventional tissue culture surfaces or to the {101} faces of the same crystals. The differences are manifested by insensitivity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011} faces, nor does trypsin post-treatment cause cell detachment from the crystals. We also noticed that the rapid adhesion to the crystal surface bears several lines of similarity to the early temporal stages in cell adhesion to regular tissue culture surfaces. Based on these observations and additional theoretical considerations, it is proposed that ·the molecular interactions responsible for the cell adhesion to the {011} surfaces may serve as models for an early engagement stage in cell adhesion which precedes, and may be essential for, the formation of stable and long-term contacts
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