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Full-Text Articles in Physics

Distance Of Closest Approach Of Two Arbitrary Hard Ellipses In Two Dimensions, Xiaoyu Zheng, Peter Palffy-Muhoray Oct 2013

Distance Of Closest Approach Of Two Arbitrary Hard Ellipses In Two Dimensions, Xiaoyu Zheng, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The distance of closest approach of hard particles is a key parameter of their interaction and plays an important role in the resulting phase behavior. For nonspherical particles, the distance of closest approach depends on orientation, and its calculation is surprisingly difficult. Although overlap criteria have been developed for use in computer simulations [ Vieillard-Baron J. Chem. Phys. 56 4729 (1972); Perram and Wertheim J. Comput. Phys. 58 409 (1985)], no analytic solutions have been obtained for the distance of closest approach of ellipsoids in three dimensions, or, until now, for ellipses in two dimensions. We have derived an analytic …


Model For The Director And Electric Field In Liquid Crystal Cells Having Twist Walls Or Disclination Lines, G. Panasyuk, David W. Allender Oct 2013

Model For The Director And Electric Field In Liquid Crystal Cells Having Twist Walls Or Disclination Lines, G. Panasyuk, David W. Allender

David W Allender

Two examples of the director structure and electric field in patterned electrode liquid crystal cells are studied using a recently developed calculational model. First, a display cell that exhibits a homeotropic to multidomainlike transition with twist wall structures has been considered for a liquid crystal with positive dielectric anisotropy. The model elucidates the behavior of the electric field. Calculations show good agreement between the model and direct computer solution of the Euler-Lagrange equations, but the model is at least 30 times faster. Second, the possibility that a cell has +/-1/2 disclination lines instead of a wall defect is probed. A …


Electric Field Standing Wave Effects In Ft-Ir Transflection Spectra Of Biological Tissue Sections: Simulated Models Of Experimental Variability, Tomasz P. Wrobel, Barbara Wajnchold, Hugh Byrne, Malgorzata Baranska Jan 2013

Electric Field Standing Wave Effects In Ft-Ir Transflection Spectra Of Biological Tissue Sections: Simulated Models Of Experimental Variability, Tomasz P. Wrobel, Barbara Wajnchold, Hugh Byrne, Malgorzata Baranska

Articles

The so-called electric field standing wave effect (EFSW) has recently been demonstrated to significantly distort FT-IR spectra acquired in a transflection mode, both experimentally and in simulated models, bringing into question the appropriateness of the technique for sample characterization, particularly in the field of spectroscopy of biological materials. The predicted effects are most notable in the regime where the sample thickness is comparable to the source wavelength. In this work, the model is extended to sample thicknesses more representative of biological tissue sections and to include typical experimental factors which are demonstrated to reduce the predicted effects. These include integration …