A simplified model of an inclusion represented by (+1)-wedge disclination and two accompanying (−1/2)-wedge disclinations on the surface of inclusion in smectic C free standing films is used to describe the elastic interaction of inclusions. The orientation of the axis connecting positions of all three disclinations relatively to the director orientation at far distances due to elastic anisotropy is investigated. The configuration with the lowest director perturbations and the lowest anisotropy elastic energy is such that the axis connecting disclinations is parallel to the distant director orientation. The interaction between inclusions at far distances is quadrupolar. The chaining of inclusions is approximately described considering their repulsion due to molecular anchoring at inclusion surfaces.PACS : 61.30.Jf

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The dielectric properties of the twist grain boundaries TGB(A) and TGB(C) of liquid crystal phases differ from the smectic-A and smectic-C phase ones: a theoretical model confirmed by experimental results shows that the Goldstone mode of the TGB(C) phase and the soft mode of the TGB(A) phase are strongly reduced. This behavior is due to elastic strain, which is connected to two parameters: the anchoring at the grain boundaries and the distance between the grain boundaries. It is shown quantitatively that a relatively flexible anchoring in the TGB(A) phase becomes rigid in the TGB(C) one. The relaxation frequencies of these modes allow analysis of the rotational viscosity variations.

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Ion transport in liquid crystals can have a negative influence on liquid crystal display performance. We introduce the importance of ion transport in industry and and the performed research. Afterwards the contribution of University of Gent will be presented in three topics: determination of concentration and mobility of ion species; influence on image sticking; role in asymmetric (reflective) cells.

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