Biomedical subjects

Figueiredo Neto AM

Publications and source records attributed to Figueiredo Neto AM.

At least 19 recordsLinked to original sources

PubMed2000

Analogy between unconventional superconductivity and unconventional states of liquid crystals

An analogy is stressed between the order-parameter symmetries of the two-dimensional d-pairing wave superconductors and of liquid-crystal mesophases formed from achiral bent-shaped molecules. It leads to a definition of a class of liquid-crystal states which are the analogs of the unconventional superconducting states, and are characterized by a loss of discrete symmetry operations of the parent state.

Journal Article↗

PubMed2000

Phase diagrams of lyotropic cholesteric fluids

Experimental investigations of lyotropic cholesterics fluids are presented which show that changes in the shape anisotropy and chirality of the micellar population determine the topology of the temperature-concentration phase diagrams. For given amounts of the substances which induce the chirality and modify the shape anisotropy of the micelles, two distinct biaxial cholesteric phases are disclosed in the phase diagrams. This is interpreted in the framework of the catastrophe theory of phase transitions.

Journal Article↗

PubMed2000

Coupling between tilt and polar orders in liquid crystal phases formed from achiral bent shaped molecules

A phenomenological description is given of the mesophases which may arise below a liquid formed from achiral molecules possessing a transverse dipole, as the result of a coupling between their tilt and polar orders. Six stable mesophases are found. Two of them have a cholesteric biaxial structure. The others display antiferroelectric or ferrielectric, incommensurately modulated, structures with in-plane or out-of-plane spontaneous polarization. The in-plane polarized structures become unstable under application of a longitudinal electric field. Other field-induced effects are discussed.

Journal Article↗

PubMed2000

Wetting-induced anisotropic structure at the interface of a glass and a sponge phase

Wetting a glass surface with a sponge phase is shown to induce an anisotropic, presumably lamellar, interface structure. This static effect, and the corresponding induced birefringence measurements, are described in the framework of a theoretical phase diagram involving the sponge and lamellar phases, and taking into account a surface field and the existence of a transition between two, direct and inverted, sponge regions.

Journal Article↗

PubMed1996