12,082 research outputs found
Precise orientation control of a liquid crystal organic semiconductor via anisotropic surface treatment
No full textWe report a three-dimensional (3D) molecular orientation control of a liquid crystal organic semiconductor (LC-OSC) based on the long-range ordering characteristic of an LC material. To this end, a synthetic LC-OSC molecule, MeOPh-BTBT-C8, with a fluidic nematic (N) phase that is essential for alignment control over a large area and a smectic E (SmE) phase showing high ordering, was prepared. A simple flipping of a sandwich cell made of the LC-OSC material between the top and bottom substrates that have uniaxial-planar degenerated alignment as well as crossed rubbing directions responds to the given surface anchoring condition and temperature gradient. Optical observation of the alignment-controlled LC-OSC was carried out by polarized optical microscopy (POM), and the corresponding charge carrier mobility was also measured by fabricating organic field-effect transistors (OFETs). Our platform offers a facile approach for multidirectional and multifunctional organic electronic devices using the stimulus-response characteristics of LC materials
Leveraging diversity in American academic medicine. The Harold Amos Medical Faculty Development Program
No full textPeer reviewe
Landsat MSS classification of fire fuel types in Wood Buffalo National Park, northern Canada
No full textJ1: Global Ecology & Biogeography Letters; M3: Article; Milne, David Franklin, Steven E. Wilson, Bradley A. Ghitter, Geoff Heathcott, Mark McCaffrey, Thomas M. Ow, Charlotte F. Y.; Source Information: Mar1994, Vol. 4 Issue 2, p33; Subject Term: FOREST fires; Author-Supplied Keyword: Canada (Wood Buffalo National Park); Author-Supplied Keyword: Forest fire; Author-Supplied Keyword: Fuel type classification; Author-Supplied Keyword: Landsat data; Number of Pages: 0p; Document Type: Articl
Structure-Property Relationships For Nanophase Segregating Groups In SmAP Mesogens
No full textThe SmAPF liquid crystal phase of the bent-core mesogen W586 represents the first reported orthogonal ferroelectric liquid crystal material, designed and prepared in the Walba group, characterized by the Clark group, and first reported in Science in 2011. The design of W586 involved the introduction of a strongly nanophase segregating group terminating the “tail” of an antiferroelectric SmAPA mesogen published by the Sadashiva group. The SmAPF phase demonstrates interesting and potentially useful electro-optic properties, including fast phase-only electrooptic modulation of light, with analog V-shape switching with optical latching. Since the synthesis of W586, the Walba group has continued the study of the SmAPF phase through the synthesis of a variety of isomers, homologs, and derivatives of W586, designed to elucidate structure-property relationships for formation of the phase, and allowing for the design of materials with properties tuned for specific applications. This work revealed a dramatic ferroelectric-antiferroelectric odd-even effect, where homologs of W586 with an odd number of methylene groups in the mesogen tail separating the core and the nanophase segregating tail terminus exhibit the SmAPF phase, while even numbered tails exhibit the SmAPA phase, though the nanophase segregating groups themselves remain identical.
Here we report the synthesis and study of new classes of SmAP mesogens which vary the nanophase segregating groups. The new mesogens involve two distinct classes of materials: first involving changes in the structure of the carbosilane nanophase segregating group found in W586, and second, materials possessing polyfluorioinated oligoethylene glycol (PFOEG) tails as the nanophase segregating group in SmAP mesogens. The latter was first reported by Korblova et al. in a system with a very different bent core. In the process, it was discovered that the antiferroelectric SmAPA phase can also exhibit V-shaped switching. This unexpected and remarkable phenomenon is shown to result from the formation of a kinetically trapped SmAPF state after initial application of an electric field.</p
Structure-Property Relationships For Nanophase Segregating Groups In SmAP Mesogens
No full textThe SmAPF liquid crystal phase of the bent-core mesogen W586 represents the first reported orthogonal ferroelectric liquid crystal material, designed and prepared in the Walba group, characterized by the Clark group, and first reported in Science in 2011. The design of W586 involved the introduction of a strongly nanophase segregating group terminating the “tail” of an antiferroelectric SmAPA mesogen published by the Sadashiva group. The SmAPF phase demonstrates interesting and potentially useful electro-optic properties, including fast phase-only electrooptic modulation of light, with analog V-shape switching with optical latching. Since the synthesis of W586, the Walba group has continued the study of the SmAPF phase through the synthesis of a variety of isomers, homologs, and derivatives of W586, designed to elucidate structure-property relationships for formation of the phase, and allowing for the design of materials with properties tuned for specific applications. This work revealed a dramatic ferroelectric-antiferroelectric odd-even effect, where homologs of W586 with an odd number of methylene groups in the mesogen tail separating the core and the nanophase segregating tail terminus exhibit the SmAPF phase, while even numbered tails exhibit the SmAPA phase, though the nanophase segregating groups themselves remain identical.
Here we report the synthesis and study of new classes of SmAP mesogens which vary the nanophase segregating groups. The new mesogens involve two distinct classes of materials: first involving changes in the structure of the carbosilane nanophase segregating group found in W586, and second, materials possessing polyfluorioinated oligoethylene glycol (PFOEG) tails as the nanophase segregating group in SmAP mesogens. The latter was first reported by Korblova et al. in a system with a very different bent core. In the process, it was discovered that the antiferroelectric SmAPA phase can also exhibit V-shaped switching. This unexpected and remarkable phenomenon is shown to result from the formation of a kinetically trapped SmAPF state after initial application of an electric field.</p
Dynamics and folding of single two-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy
No full textWe report single-molecule measurements on the folding and unfolding conformational equilibrium distributions and dynamics of a disulfide crosslinked version of the two-stranded coiled coil from GCN4. The peptide has a fluorescent donor and acceptor at the N termini of its two chains and a Cys disulfide near its C terminus. Thus, folding brings the two N termini of the two chains close together, resulting in an enhancement of fluorescent resonant energy transfer. End-to-end distance distributions have thus been characterized under conditions where the peptide is nearly fully folded (0 M urea), unfolded (7.4 M urea), and in dynamic exchange between folded and unfolded states (3.0 M urea). The distributions have been compared for the peptide freely diffusing in solution and deposited onto aminopropyl silanized glass. As the urea concentration is increased, the mean end-to-end distance shifts to longer distances both in free solution and on the modified surface. The widths of these distributions indicate that the molecules are undergoing millisecond conformational fluctuations. Under all three conditions, these fluctuations gave nonexponential correlations on 1- to 100-ms time scale. A component of the correlation decay that was sensitive to the concentration of urea corresponded to that measured by bulk relaxation kinetics. Thetrajectories provided effective intramolecular diffusion coefficients as a function of the end-to-end distances for the folded and unfolded states. Single-molecule folding studies provide information concerning the distributions of conformational states in the folded, unfolded, and dynamically interconverting states.Author manuscript. Published in final edited form as: Proc Natl Acad Sci U S A. 2000 November 21; 97(24): 13021-13026.The final published version of this article is located at: http://www.pnas.org/cgi/reprint/97/24/13021NIH GM54616; to William F. DeGradoNIH GM12592; to Robin M. HochstrasserNIH GM48130; to William F. Degrado and Robin M. HochstrasserThis work was supported by GM54616 (to W.F.D.), GM12592 (to R.M.H.) and GM48130 (to W.F.D. and R.M.H.) with instrumentation developed under RR01348. D.S.T. was supported by National Institutes of Health Grant NRSA F32-GM18589.Also available in PubMed Central. PMCID:PMC2717
TRAUMATIC IDENTITY AND AURA IN DAVID LODGE’S AUTHOR, AUTHOR
No full textThis paper delves into David Lodge’s Author, Author (2004) as an example of neo-Victorian celebrity biofiction, more concretely on Henry James. The genre belongs to the wave of Victorian revival in current literature which also affects cultural studies in general. My main contention is that Lodge’s novel responds to current cultural anxieties, particularly the crisis of identity and authorship and the end of Walter Benjamin’s concept of aura, by sublimating them into late-nineteenth-century traumata. The choice of James is, the article argues, not casual. He represents the redeeming figure of a lost auratic world; the human in crisis, traumatized because he does not fit in the new status quo.Este artículo analiza la novela Author, Author (2004) de David Lodge como ejemplo de bioficción neo-victoriana centrada en una celebridad, en este caso concreto, Henry James. El género forma parte del renacimiento victoriano actual que afecta a los estudios culturales en su conjunto. Mi argumento central es que la novela de Lodge constituye una respuesta a las ansiedades culturales actuales, en particular a las que se refieren a la crisis identitaria y autoría literaria, así como a la pérdida del aura artística de Walter Benjamin, sublimándolas a través de los traumas de finales del siglo XIX. La elección de James, como demuestra el artículo, no es casual. Es el último representante de un mundo perdido en el que el aura aún tenía un espacio; el ser humano en crisis y traumatizado porque no encaja en un status quo nuevo
Orientation control over bent-core smectic liquid crystal phases
No full textBent-core smectic liquid crystal (LC) phases (B phases) have been widely studied since their unusual polar and chiral properties were discovered in the 1990s. Relatively few studies have examined the mechanisms by which the orientation of the B phase may be controlled to produce the type of macroscopic domain that is essential for organic semiconductor, optical device and patterning applications. This review is intended to cover recent progress towards controlling the B phases upon layering, including anisotropic treatment methods and topographical confinement methods. Finally, this review closes with a discussion of B smectic phases that have been fabricated for use in certain applications
Extreme nanoseparation by dual-confining effect : Binary mixtures of bent core and rod-like liquid crystals in confined geometry
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