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447 results on '"Wyatt, Peter"'

6. Grating aligned ferroelectric liquid crystal devices

Author

Wyatt, Peter James McCormack, Jones, J. Cliff, and Nagaraj, Mamatha

Subjects
530.4
Abstract

This thesis is concerned with the vertical grating alignment of ferroelectric liquid crystals (FLCs). FLCs exhibit fast electro-optic response times compared to traditional nematic devices, and so are of particular interest for use in micro-displays and liquid crystal on silicon (LCoS) spatial light modulators. Unfortunately such materials are highly susceptible to shock induced ow. This work introduces the VGA-FLC device geometry: a vertical grating aligned ferroelectric liquid crystal display. The vertical alignment gives preferential alignment to the smectic layers, and the amplitude and pitch of the grating ensure stable alignment of the c-director of the FLC. The combined effect is shown to result in a shock-stable FLC geometry. The device is addressed with in-plane electric fields, and is shown to obtain fast optical response times. The theory and physics of the device is explored, and further experiments are suggested that can be performed for device optimisation.

Published
2019

8. (S)-1-Methyl-2-oxoimidazolidine-4-carboxylic Acid.

Author

Dey, Ashley L., Motevalli, Majid, Abrahams, Isaac, and Wyatt, Peter B.

Subjects
HYDROGEN bonding, PEPTIDE hormones, PROPIONIC acid, SPACE groups, MASS spectrometry
Abstract

(S)-1-Methyl-2-oxoimidazolidine-4-carboxylic acid 1 is an analog of (S)-pyroglutamic acid, a key component of naturally occurring peptide hormones and synthetic pharmaceutical candidates. The reaction of (S)-2-amino-3-(methylamino)propionic acid with COCl2 and aqueous NaHCO3 followed by ion exchange afforded 1, which was recrystallized from acetonitrile and then characterized by IR, 1H NMR, 13C NMR, polarimetry, elemental microanalysis, high-resolution mass spectrometry and single-crystal X-ray diffraction. The acid 1 crystallized in the orthorhombic chiral space group P212121 with cell constants a = 6.2275(4) Å, b = 8.3963(5) Å, c = 24.9490(14) Å. The X-ray crystal structure revealed that two distinct conformers of 1 occur at alternating positions within helices which are supported by hydrogen bonds. Each molecule of 1 is linked to its two neighbors in the helix by a total of three hydrogen bonds, and four molecules of 1 are contained within each turn of the helix. The pattern of hydrogen bonds illustrates a preference for the carboxylic acid group to act as a hydrogen bond donor and for the urea unit to be a hydrogen bond acceptor. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Epitaxial graphene transistors on SiC substrates

Author

Kedzierski, Jakub, Hsu, Pei-Lan, Healey, Paul, Wyatt, Peter, Keast, Craig, Sprinkle, Mike, Berger, Claire, and de Heer, Walt

Subjects
Condensed Matter - Materials Science
Abstract

This paper describes the behavior of top gated transistors fabricated using carbon, particularly epitaxial graphene on SiC, as the active material. In the past decade research has identified carbon-based electronics as a possible alternative to silicon-based electronics. This enthusiasm was spurred by high carbon nanotube carrier mobilities. However, nanotube production, placement, and control are all serious issues. Graphene, a thin sheet of graphitic carbon, can overcome some of these problems and therefore is a promising new electronic material. Although graphene devices have been built before, in this work we provide the first demonstration and systematic evaluation of arrays of a large number of transistors entirely produced using standard microelectronics methods. Graphene devices presented feature high-k dielectric, mobilities up to 5000 cm2/Vs and, Ion/Ioff ratios of up to 7, and are methodically analyzed to provide insight into the substrate properties. Typical of graphene, these micron-scale devices have negligible band gaps and therefore large leakage currents.

Published
2008
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25. An SOI-Based 3D Circuit Integration Technology

Author

Burns, James, Aull, Brian, Berger, Robert, Checka, Nisha, Chen, Chang-Lee, Chen, Chenson, Gouker, Pascale, Keast, Craig, Knecht, Jeffrey, Soares, Antonio, Suntharalingam, Vyshnavi, Tyrrell, Brian, Warner, Keith, Wheeler, Bruce, Wyatt, Peter, Yost, Donna, Tan, Chuan Seng, editor, Gutmann, Ronald J., editor, and Reif, L. Rafael, editor

Published
2008
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