M. Simões

University of Lisbon

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A. J. Palangana

Universidade Estadual de Maringá

N.M. Kimura

Universidade Estadual de Maringá

D.D. Lüders

Universidade Estadual de Maringá

Oscar Rodrigues dos Santos

Universidade Tecnológica Federal do Paraná

Anderson Reginaldo Sampaio

Universidade Estadual de Maringá

W.S. Braga

Universidade Tecnológica Federal do Paraná

D. S. Simeão

Universidade Tecnológica Federal do Paraná

S. M. Domiciano

Universidade Tecnológica Federal do Paraná

A. de Campos

Aix-Marseille Université

K. Yamaguti

Universidade Estadual de Londrina

Cooperative Institutions

Universidade Estadual de Londrina

Centre National de la Recherche Scientifique

Universidade Estadual de Maringá

Inserm

Université de Lille

Centre Hospitalier Universitaire de Lille

Institut Pasteur de Lille

Joint Institute for Nuclear Research

Universidade Tecnológica Federal do Paraná

Institut de Biologie Structurale

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Landau–de Gennes model for nonuniform configurations in nematic liquid crystalline elastomers

Physical Review E (2004)

M. Simões A. de Campos

Through a mean field theory, an elastic free energy describing the nonuniform elastic textures observed in nematic elastomers, is proposed. To construct it, an order parameter that describes the nematic-isotropic phase transition through the change of the elastic properties of the strain tensor at the transition point is introduced. The resulting elastic free energy can be written in a form that resembles the Frank free energy of the usual nematic liquid crystals, becoming equivalent to it when the size of the elastic nematic domains is a fixed constant along the whole sample. Using this approach, a model for nonhomogeneous deformations found by Macromolecules 33, 7675 (2000)] in elastomeric thin films of urethane/urea is proposed.

Elastic energy

Biaxial nematic

Elasticity

Mean field theory

10.1103/physreve.69.061704

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Citations (3)

An optical conoscopy study of a reentrant discotic nematic—Biaxial nematic phase transition

Journal of Molecular Liquids (2012)

W.S. Braga Oscar Rodrigues dos Santos Anderson Reginaldo Sampaio N.M. Kimura M. Simões

Reentrancy

Biaxial nematic

Lyotropic

10.1016/j.molliq.2012.03.007

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Citations (23)

A Geometrical Approach to the Miesowicz's Coefficients

Molecular Crystals and Liquid Crystals (2013)

S. M. Domiciano M. Simões D. S. Simeão F. S. Alves

Here we will show how the use of a geometrical approach leads to a reduction of the number of the viscosity coefficients of the nematic liquid crystals. Usually they are described by five free parameters; we will show that a geometrical approach can reduce this number to three. This result will follow from the modified version of the Hess-Baalss approach. As a consequence of the application of the Onsager relation, these three viscosity terms become related by the effective eccentricity of the nematic grain, leading to a connection between the Miesowicz's coefficients.

Eccentricity (behavior)

10.1080/15421406.2013.789697

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Citations (1)

Calculation of the nematic entropy using digital images

Physical Review E (2013)

F. C. M. Freire N.M. Kimura D.D. Lüders A. J. Palangana M. Simões

In this work we will use digital images to compute the entropy dependence on temperature of a nematic lyotropic sample. The set of images comprehend the entire temperature range between a reentrant nematic isotropic phase transition, at a low temperature, and a usual nematic isotropic phase transition at a higher temperature. We will show that, inside the nematic phase, the image entropy profile agrees accurately with the entropy given by the Maier-Saupe model. As far as we know, this is the first time that the entropy of a lyotropic nematic phase is evaluated by this method, which introduces a way to measure their macroscopic variables. Namely, being that the entropy is a thermodynamical potential, this result implies that digital images can be used to compute mean values of nematic random variables.

Lyotropic

Reentrancy

10.1103/physreve.88.064502

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Citations (4)

Global behaviour of the order parameter in nematic phase

Liquid Crystals (2011)

M. Simões D. S. Simeão K. Yamaguti

Abstract In this paper we study the behaviour of the order parameter of the nematic phase for all temperatures of the phase: from the neighbourhoods of the nematic crystalline phase transition region to the neighbourhoods of the nematic isotropic phase transition region. To do this, we use experimental birefringence data and thermal anisotropy conductivity data in a recursive process that makes an independent and local calculation of the order parameter exponent β(T) for each temperature value T. With these data, and with this procedure, we construct the profile of β(T) and reveal that it remains constant along the entire range of the phase. Keywords: nematic phaseorder parameterorder parameter exponent Acknowledgements We are grateful to the Brazilian Agencies CAPES, Fundação Araucária (PR) and CNPq for financial support given to this work.

Exponent

Biaxial nematic

10.1080/02678292.2011.587131

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Citations (17)

Micellar shape anisotropy on lyotropic nematic phases

Physica A Statistical Mechanics and its Applications (2010)

M. Simões M. Pazetti N.M. Kimura A. J. Palangana

In this work we show, that with the introduction of the micellar shape anisotropy in the order parameter of a lyotropic liquid crystal, it is possible to understand, in a unified way, the features observed in the phase diagram of these materials. Using the de Gennes connection between microscopic and macroscopic order parameters, such an extended order parameter is constructed from a geometrical conception of the micelles. Our theoretical results will be correlated with refractive index experimental data near the uniaxial–biaxial nematic phase transitions of a lyotropic mixture of potassium laurate, decanol and deuterium oxide.

Lyotropic

Lyotropic liquid crystal

Biaxial nematic

10.1016/j.physa.2010.05.056

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Citations (4)

Beta-neutrino angular correlation in the decay of 18Ne

Nuclear Physics A (1997)

V. Egorov Ch. Briançon V. Brudanin J.S. Dionisio J. Deutsch

Beta decay

BETA (programming language)

Coupling constant

Beta particle

10.1016/s0375-9474(97)00178-4

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Citations (21)

Corresponding states of periodic structures in nematic liquid crystals

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics (1997)

A. J. Palangana M. Simões L. R. Evangelista A. A. Arrotéia

The discovery of a universal behavior for the distortion of one-dimensional walls, formed in nematic liquid crystal samples under the action of a magnetic field, above the Fr\'eedericksz threshold is reported. By means of a simple theoretical approach it is shown that the length of these walls, when properly scaled and considered as a function of the reduced magnetic field, stays in a common line of corresponding states. This behavior is confirmed by experimental data on lyotropic as well as in thermotropic nematic liquid crystals.

Thermotropic crystal

Lyotropic

Biaxial nematic

Distortion (music)

10.1103/physreve.56.4282

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Citations (12)

Viscosity of Lyotropic Nematic Calamitic Liquid Crystals

Molecular crystals and liquid crystals science technology. Section A, Molecular crystals and liquid crystals/Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals (2001)

Anderson Reginaldo Sampaio P. R. G. Fernandes M. Simões A. J. Palangana

(2001). Viscosity of Lyotropic Nematic Calamitic Liquid Crystals. Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals: Vol. 359, No. 1, pp. 269-275.

Lyotropic

10.1080/10587250108035586

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Citations (6)

Chaotic motion of magnetotactic bacteria

Chaos Solitons & Fractals (2000)

Pedro Henrique Arruda Aragão M. Simões

Magnetotactic Bacteria

10.1016/s0960-0779(98)00257-4

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Citations (3)