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301.
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Radny MW Smith PV Reusch TC Warschkow O Marks NA Shi HQ McKenzie DR Schofield SR Curson NJ Simmons MY 《The Journal of chemical physics》2007,127(18):184706
Using first-principles density functional theory, we discuss doping of the Si(001) surface by a single substitutional phosphorus or arsenic atom. We show that there are two competing atomic structures for isolated Si-P and Si-As heterodimers, and that the donor electron is delocalized over the surface. We also show that the Si atom dangling bond of one of these heterodimer structures can be progressively charged by additional electrons. It is predicted that surface charge accumulation as a result of tip-induced band bending leads to structural and electronic changes of the Si-P and Si-As heterodimers which could be observed experimentally. Scanning tunneling microscopy (STM) measurements of the Si-P heterodimer on a n-type Si(001) surface reveal structural characteristics and a bias-voltage dependent appearance, consistent with these predictions. STM measurements for the As:Si(001) system are predicted to exhibit similar behavior to P:Si(001). 相似文献
304.
G. W. Milton R. C. McPhedran D. R. McKenzie 《Applied Physics A: Materials Science & Processing》1981,25(1):23-30
Formalisms are presented which enable the accurate calculation of the polarizability of an isolated square prism, and of the
transport properties of square arrays of both circular cylinders and square prisms, over the entire range of volume fractions.
For volume fractions close to zero and to unity, the results are shown to agree with dipolar formulae based on the appropriate
polarizability. For volume fractions close to touching, the transport property varies rapidly but smoothly through the multipolar
region. The results are shown to be in good qualitative agreement with experimental curves. 相似文献
305.
P. Mullen A. McKenzie D. Pavlov L. Durant Y. Tong E. Kanso J. E. Marsden M. Desbrun 《Foundations of Computational Mathematics》2011,11(2):151-149
In this paper, we present a numerical technique for performing Lie advection of arbitrary differential forms. Leveraging advances
in high-resolution finite-volume methods for scalar hyperbolic conservation laws, we first discretize the interior product
(also called contraction) through integrals over Eulerian approximations of extrusions. This, along with Cartan’s homotopy formula and a discrete
exterior derivative, can then be used to derive a discrete Lie derivative. The usefulness of this operator is demonstrated
through the numerical advection of scalar fields and 1-forms on regular grids. 相似文献
306.
P. Mullen A. McKenzie D. Pavlov L. Durant Y. Tong E. Kanso J. E. Marsden M. Desbrun 《Foundations of Computational Mathematics》2011,11(2):131-149
In this paper, we present a numerical technique for performing Lie advection of arbitrary differential forms. Leveraging advances in high-resolution finite-volume methods for scalar hyperbolic conservation laws, we first discretize the interior product (also called contraction) through integrals over Eulerian approximations of extrusions. This, along with Cartan’s homotopy formula and a discrete exterior derivative, can then be used to derive a discrete Lie derivative. The usefulness of this operator is demonstrated through the numerical advection of scalar fields and 1-forms on regular grids. 相似文献
307.
Lafleur L Stevens D McKenzie K Ramachandran S Spicar-Mihalic P Singhal M Arjyal A Osborn J Kauffman P Yager P Lutz B 《Lab on a chip》2012,12(6):1119-1127
In many low resource settings multiple diseases are endemic. There is a need for appropriate multi-analyte diagnostics capable of differentiating between diseases that cause similar clinical symptoms. The work presented here was part of a larger effort to develop a microfluidic point-of-care system, the DxBox, for sample-to-result differential diagnosis of infections that present with high rapid-onset fever. Here we describe a platform that detects disease-specific antigens and IgM antibodies. The disposable microfluidic cards are based on a flow-through membrane immunoassay carried out on porous nitrocellulose, which provides rapid diffusion for short assay times and a high surface area for visual detection of colored assay spots. Fluid motion and on-card valves were driven by a pneumatic system and we present designs for using pneumatic control to carry out assay functions. Pneumatic actuation, while having the potential advantage of inexpensive and robust hardware, introduced bubbles that interfered with fluidic control and affected assay results. The cards performed all sample preparation steps including plasma filtration from whole blood, sample and reagent aliquoting for the two parallel assays, sample dilution, and IgG removal for the IgM assays. We demonstrated the system for detection of the malarial pfHRPII antigen (spiked) and IgM antibodies to Salmonella Typhi LPS (patient plasma samples). All reagents were stored on card in dry form; only the sample and buffer were required to run the tests. Here we detail the development of this platform and discuss its strengths and weaknesses. 相似文献
308.
We analyze the low-energy electronic structure of a series of symmetric cationic diarylmethanes, which are bridge-substituted derivatives of Michler's Hydrol Blue. We use a four-electron, three-orbital complete active space self-consistent field and multi-state multi-reference perturbation theory model to calculate a three-state diabatic effective Hamiltonian for each dye in the series. We exploit an isolobal analogy between the active spaces of the self-consistent field solutions for each dye to represent the electronic structure in a set of analogous diabatic states. The diabatic states can be identified with the bonding structures in classical resonance-theoretic models of cyanine dyes. We identify diabatic states with opposing charge and bond-order localization, analogous to the classical resonance structures, and a third state with charge on the bridge. While the left- and right-charged structures are similar for all dyes, the structure of the bridge-charged diabatic state, and the Hamiltonian matrix elements connected to it, change significantly across the series. The change is correlated with an inversion of the sign of the charge carrier on the bridge, which changes from an electron pair to a hole as the series is traversed. 相似文献
309.
310.
Tove Wiklund Christine J. McKenzie Anders Lennartson 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(8):o410-o413
2‐[(2‐Ammonioethyl)amino]acetate dihydrate, better known as N‐(2‐aminoethyl)glycine dihydrate, C4H10N2O2·2H2O, (I), crystallizes as a three‐dimensional hydrogen‐bonded network. Amino acid molecules form layers in the ac plane separated by layers of water molecules, which form a hydrogen‐bonded two‐dimensional net composed of fused six‐membered rings having boat conformations. The crystal structure of the corresponding hydroiodide salt, namely 2‐[(2‐ammonioethyl)ammonio]acetate iodide, C4H11N2O2+·I−, (II), has also been determined. The structure of (II) does not accommodate any solvent water molecules, and displays stacks of amino acid molecules parallel to the a axis, with iodide ions located in channels, resulting in an overall three‐dimensional hydrogen‐bonded network structure. N‐(2‐Aminoethyl)glycine is a molecule of considerable biological interest, since its polyamide derivative forms the backbone in the DNA mimic peptide nucleic acid (PNA). 相似文献