Cholesteric
Mostrando 1-12 de 20 artigos, teses e dissertações.
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1. Calculation of reflectance and transmittance of optical birefringent networks based on cholesteric liquid crystals
Abstract In this paper we calculated reflectance and transmittance of different optical birefringent networks sandwiched between two isotropic media. To model optical phenomena in the considered systems, we applied the 4×4 matrix method. Some interesting reflectance and transmittance spectra and polar plots for different system parameters and arbitrary inci
Lat. Am. j. solids struct.. Publicado em: 18/02/2019
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2. Experimental evidence of an optical shutter in cholesteric phase of a double hydrogen bonded liquid crystal
A novel series of double hydrogen bonded liquid crystals have been isolated. Hydrogen bond was formed between non mesogen chiral ingredient levo tartaric acid (LTA) and mesogenic undecyloxy benzoic acids (11BA) Thermal and electrical properties exhibited by levo tartaric acid and undecyloxy benzoic acid (LTA+11BA) were discussed. Interesting feature of the p
Brazilian Journal of Physics. Publicado em: 2009-12
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3. DEVELOPMENT AND CHARACTERIZATION OF A CHOLESTERIC LIQUID CRYSTAL LASER SYSTEM COUPLED TO AN OPTICAL FIBER / DESENVOLVIMENTO E CARACTERIZAÇÃO DE UM SISTEMA LASER DE CRISTAL LÍQUIDO COLESTÉRICO ACOPLADO À FIBRA ÓPTICA
Neste trabalho estudamos a viabilidade do desenvolvimento de um sistema laser de cristal líquido colestérico (CLC) acoplado a fibra óptica visando sua aplicação como um sensor de temperatura. Sensores laser de CLC acoplados a fibra óptica são atrativos devido às enormes vantagens que as fibras ópticas apresentam e à resposta de cristais líquidos a
Publicado em: 2004
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4. Fiber coupled cholesteric liquid crystal laser
Lasing in cholesteric liquid crystals is an exciting new phenomenon. Cholesteric liquid crystals (CLC) are inherently periodic. In their ground state, they form a structure where the optic axis of the uniaxial material twists to form a helix and leads to one dimensional photonic band-gap behavior. If a fluorescent dye with emission matching the reflection ba
Brazilian Journal of Physics. Publicado em: 2002-06
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5. Twenty years of research on cholesteric lyotropic liquid crystals at the Chemistry Institute of the University of São Paulo
In this paper we present a review of twenty years of research on cholesteric liquid crystals at the Chemistry Institute of the University of São Paulo. The results on the interaction forces, responsible for the maintenance of the helical structure, are a function of the chemical variability obtained in these systems. The last results obtained using rheologi
Brazilian Journal of Physics. Publicado em: 2002-06
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6. Smectic A: cholesteric phase transition investigated by small angle X-ray diffraction and viscosity measurements
We have studied the in influence of the mean molecular length on the nature of the cholesteric (N*) – smectic A (A) liquid crystal phase transition for thermotropic compounds of cholesteryl myristate (C14), cholesteryl nonanoate (C9), and binary mixtures of C14 – C9 and cholesteryl caproate (C6) phase (dA), the mean molecular length ( Brazilian Journal of Physics. Publicado em: 2002-06
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7. 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
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8. Propriedades reológicas e magnéticas de liomesofases colestéricas uni e biaxiais / Rheological and magnetic properties of uni and biaxial cholesteric liomesophases
In this work, several techniques were used to study mesophases constituted by potassium laurate, decylammonium chloride, water and brucine sulfate. This system was chosen for presenting a cholesteric biaxial phase, whose characterization continues to be worthy of investigation. Rheological measurements were made on nematic and cholesteric systems, in differe
Publicado em: 1999
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9. Investigações envolvendo titulação termometrico catalitica
The influence of the composition of titrand and titrant on the shape of titration graph involved in the alkalimetric titration of acids in water-dimethylsulfoxide-acrylonitrile medium by catalytic thermometric titrimetry has been investigated. In this study it was possible to suggest the reaction responsible for the rise in temperature for different composit
Publicado em: 1989
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10. Polyamine structural effects on the induction and stabilization of liquid crystalline DNA: potential applications to DNA packaging, gene therapy and polyamine therapeutics
DNA undergoes condensation, conformational transitions, aggregation and resolubilization in the presence of polyamines, positively charged organic molecules present in all cells. Under carefully controlled environmental conditions, DNA can also transform to a liquid crystalline state in vitro. We undertook the present work to examine the ability of spermidin
Oxford University Press.
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11. Supramolecular ordering of DNA in the cholesteric liquid crystalline phase: an ultrastructural study.
Aqueous solutions of 146-base pair DNA fragments form a cholesteric liquid crystalline phase in the range of about 160-290 mg/ml. We present a structural analysis of this phase by comparing the data obtained from polarizing and electron microscopy. This phase shows multiple aspects or "textures" which are presented and interpreted. They mainly depend on the
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12. Study of DNA films by the CD, X-ray and polarization microscopy techniques.
DNA films with psi +/- CD spectra have been investigated. X-ray analysis has shown the sign of the psi spectra to be independent of the secondary structure of DNA. The appearance of the psi spectra is attended by the formation of a characteristic polygonal texture of the cholesteric type in the DNA film.