1,349 research outputs found
Atomic Layer Deposition Nucleation Dependence on Diamond Surface Termination
Surface termination and interfacial interactions are critical for advanced
solid-state quantum applications. In this paper, we demonstrate that atomic
layer deposition (ALD) can both provide valuable insight on the chemical
environment of the surface, having sufficient sensitivity to distinguish
between the common diamond (001) surface termination types and passivate these
interfaces as desired. We selected diamond substrates exhibiting both smooth
and anomalously rough surfaces to probe the effect of morphology on ALD
nucleation. We use high resolution in situ spectroscopic ellipsometry to
monitor the surface reaction with sub-angstrom resolution, to evaluate the
nucleation of an ALD Al2O3 process as a function of different ex and in situ
treatments to the diamond surface. In situ water dosing and high vacuum
annealing provided the most favorable environment for nucleation of
dimethylaluminum isopropoxide and water ALD. Hydrogen termination passivated
both smooth and rough surfaces while triacid cleaning passivated the smooth
surface only, with striking effectiveness.Comment: 31 pages, 14 figure
Soliton approximation in continuum models of leader-follower behavior
Complex biological processes involve collective behavior of entities
(bacteria, cells, animals) over many length and time scales and can be
described by discrete models that track individuals or by continuum models
involving densities and fields. We consider hybrid stochastic agent-based
models of branching morphogenesis and angiogenesis (new blood vessel creation
from pre-existing vasculature), which treat cells as individuals that are
guided by underlying continuous chemical and/or mechanical fields. In these
descriptions, leader (tip) cells emerge from existing branches and follower
(stalk) cells build the new sprout in their wake. Vessel branching and fusion
(anastomosis) occur as a result of tip and stalk cell dynamics. Coarse-graining
these hybrid models in appropriate limits produces continuum partial
differential equations (PDEs) for endothelial cell densities that are more
analytically tractable. While these models differ in nonlinearity, they produce
similar equations at leading order when chemotaxis is dominant. We analyze this
leading order system in a simple quasi-one-dimensional geometry and show that
the numerical solution of the leading order PDE is well described by a soliton
wave that evolves from vessel to source. This wave is an attractor for
intermediate times until it arrives at the hypoxic region releasing the growth
factor. The mathematical techniques used here thus identify common features of
discrete and continuum approaches and provide insight into general biological
mechanisms governing their collective dynamics.Comment: 13 pages, 9 figure
Foliar Fungicides in Seed Corn Production
Since 1982, we have conducted a program to determine the fungicides that may be effective for controlling foliar diseases in inbred and hybrid com. For the past seven years we have limited our research to only inbreds or sister line hybrids. In 1990, we started a cooperative program with seed companies and have conducted our research in commercial seed production fields in five greatly different years in terms of weather patterns. Thirty experiments have been established in seed production fields and 25 fields have been harvested for yield. Five experiments were abandoned because of herbicide injury interactions (2,4-D) with the fungicides, excessive Stewarts disease (a bacterial disease that can not be controlled with fungicides and was devastating), or drought
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The Edge Admittance of a Wide Microstrip Patch Seen by an Obliquely Incident Wave
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A Generalized Edge Boundary Condition for Open Microstrip Structures
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A Note on the Edge Admittance of a Wide Microstrip Patch with electrically Thin Substrate
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