Orientational Order
Mostrando 1-12 de 26 artigos, teses e dissertações.
-
1. Transições de fase em polimeros liquido-cristalinos de cadeia lateral / Phase transitions in side-chain liquid-cristaline polmers
Polymeric liquid crystals are materials that combine properties of both polymers and liquid crystals. These polymers can be thought as block copolymers made of ftexible and rigid molecular blocks. As in flexible block copolymers, the macrophase separation originated from the repulsion between different blocks is frustrated by the connectivity constraint impo
Publicado em: 2007
-
2. Efeitos de superfície nas propriedades térmicas e dinâmicas de filmes de cristais líquidos esméticos. / Surface effects on the thermal and dynamical proprieties of smectic liquid crystal filmes.
The thermal and dynamical properties of free-standing films are strongly dependent on the boundary conditions and the presence of an external field. Using distinct theoretical models and the dynamic light scattering experimental setup, we study the surface and external field effects on the relaxation dynamics, fluctuation-induced interaction energy, and phas
Publicado em: 2007
-
3. Estudo da orientação molecular em filmes automontados de azopolímeros por meio da técnica de geração de segundo harmônico (SHG) / Molecular orientation in self-assembled azo-polymer thin films studied by second harmonic generation (SHG).
Ultrathin films of polymers containing azochromophores are important for many applications such as optical data storage, formation of surface relief gratings, liquid crystal alignment layers and non-linear optical devices. Among several techniques for fabricating organic thin films, the Layer-By-Layer electrostatic self-assembly (LBL) is very attractive due
Publicado em: 2006
-
4. Surface and confinement effects on the orientational order of liquid crystals / "Efeitos de superfície e de confinamento na ordem orientacional de cristais líquidos"
Neste trabalho investigamos os efeitos de superfícies de contorno e de confinamento na ordem orientacional de cristais líquidos, onde utilizamos cristais líquidos termotrópicos e liotrópicos. A importância deste estudo deve-se à aspectos tanto de interesse tecnológico (formas de alinhamento) como de pesquisa básica. Com relação aos cristais líqui
Publicado em: 2004
-
5. Estados críticos orientacionais em cristais líquidos liotrópicos induzidos por campos magnéticos. / Orientations critical states in lyotropic liquid crystals induced by magnetic fields.
Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are u
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/12/2000
-
6. Estudo de Fases Termotrópicas por Microscopia Óptica, Medidas de Densidade, Entálpicas e Espalhamento de Raios X / Thermotropic phase study, by optical microscopy, density and calorimetric measurements and X-ray scattering.
The influence of the mean molecular length on the nature of the smectic A (SA)- cholesteric (C) liquid crystal phase transition has been studied for cholesteryl myristate (C14), cholesteryl nonanoate (C9) and binary mixtures of C14 and C9 and cholesteryl caproate (C6) and C9. Optical microscopy was carried out to determine the temperatures of the SAC as weel
Publicado em: 2000
-
7. Fast and slow orientational fluctuations in membranes
Fluorescence anisotropy measurements on isotropically distributed membranes yield the well-known orientational order parameter as a measure of orientational fluctuations of the fluorophore that are fast compared to the fluorescence lifetime. Measurements on oriented membranes provide four order parameters, two for fast orientational fluctuations and two for
-
8. Studies of highly asymmetric mixed-chain diacyl phosphatidylcholines that form mixed-interdigitated gel phases: Fourier transform infrared and 2H NMR spectroscopic studies of hydrocarbon chain conformation and orientational order in the liquid-crystalline state.
Hydrocarbon chain conformational and orientational order in liquid-crystalline bilayers of the highly chain-asymmetric 1-O-eicosanoyl, 2-O-dodecanoyl and 1-O-decanoyl, 2-O-docosanoyl phosphatidylcholines were studied by Fourier transform infrared (FTIR) and deuterium nuclear magnetic resonance (2H-NMR) spectroscopy, respectively, and compared with appropriat
The Biophysical Society.
-
9. Bond orientational order, molecular motion, and free energy of high-density DNA mesophases.
By equilibrating condensed DNA arrays against reservoirs of known osmotic stress and examining them with several structural probes, it has been possible to achieve a detailed thermodynamic and structural characterization of the change between two distinct regions on the liquid-crystalline phase diagram: (i) a higher density hexagonally packed region with lon
-
10. Correlation between lipid plane curvature and lipid chain order.
The 1-palmitoyl-2-oleoyl-phosphatidylethanolamine: 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE:POPC) system has been investigated by measuring, in the inverted hexagonal (HII) phase, the intercylinder spacings (using x-ray diffraction) and orientational order of the acyl chains (using 2H nuclear magnetic resonance). The presence of 20 wt% dodecane leads t
-
11. Structural order of lipids and proteins in membranes: evaluation of fluorescence anisotropy data.
The limiting long-time value of fluorescence anisotropy in membranes is correlated with the orientational order parameter, which characterizes the structural anisotropy of membranes. Existing experimental results for diphenylhexatriene in lipid bilayers are evaluated for the order parameter of lipid order. Steady-state measurements of fluorescence anisotropy
-
12. Orientational Order of the Lamellipodial Actin Network as Demonstrated in Living Motile CellsV⃞
Lamellipodia of crawling cells represent both the motor for cell advance and the primary building site for the actin cytoskeleton. The organization of actin in the lamellipodium reflects actin dynamics and is of critical importance for the mechanism of cell motility. In previous structural studies, the lamellipodial actin network was analyzed primarily by el
The American Society for Cell Biology.