Broad temperature range ferrielectric liquid crystal as a highly sensitive quadratic electro-optical material.

A chiral smectic liquid crystal in which a ferrielectric phase with a helix pitch p less than 125 nm exists over a temperature range of at least from -3°C to +36°C has been developed. Such a wide temperature range (including room temperatures) of the ferrielectric phase with a subwavelength helix pitch has been achieved for the first time, to the best of our knowledge, which creates opportunities for the practical use of ferrielectric liquid crystals. A quadratic electro-optical effect caused by deformations of the helix in an electric field is observed in the ferrielectric phase, and the Kerr coefficient, which reaches almost 200 nm/V, is significantly higher than the same coefficient for the blue phase and for the smectic C* phase, which means a higher sensitivity of the developed ferrielectric liquid crystal to the electric field.

Short bent-core molecules: X-ray, polarization, dielectricity, texture and electro-optics investigations.

Bent-core liquid crystals based on 1,2,4-oxadiazole as a central unit have been the first mesogens to exhibit a ferroelectric response in the nematic phase. This behavior has been widely recognized as due to the presence of smectic-like polar cybotactic clusters permeating the nematic phase. Unfortunately, these compounds exhibited rather high melting points, about 120 °C, due to the presence of four benzene rings in the molecules.

Enhanced orientational Kerr effect in vertically aligned deformed helix ferroelectric liquid crystals.

We disclose the vertically aligned deformed helix ferroelectric liquid crystal whose Kerr constant (Kkerr≈130  nm/V2 at λ=543  nm) is around one order of magnitude higher than any other value previously reported for liquid crystalline structures. Under certain conditions, the phase modulation with ellipticity less than 0.05 over the range of continuous and hysteresis-free electric adjustment of the phase shift from zero to 2π has been obtained at subkilohertz frequency.

Neural migration. Structures of netrin-1 bound to two receptors provide insight into its axon guidance mechanism.

Netrins are secreted proteins that regulate axon guidance and neuronal migration. Deleted in colorectal cancer (DCC) is a well-established netrin-1 receptor mediating attractive responses. We provide evidence that its close relative neogenin is also a functional netrin-1 receptor that acts with DCC to mediate guidance in vivo.

Orientational Kerr effect and phase modulation of light in deformed-helix ferroelectric liquid crystals with subwavelength pitch.

We study both theoretically and experimentally the electro-optical properties of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLC) with subwavelength pitch that are governed by the electrically induced optical biaxiality of the smectic helical structure. The key theoretical result is that the principal refractive indices of homogenized VADHFLC cells exhibit the quadratic nonlinearity and such behavior might be interpreted as an orientational Kerr effect caused by the electric-field-induced orientational distortions of the FLC helix. In our experiments, it has been observed that, for sufficiently weak electric fields, the magnitude of biaxiality is proportional to the square of electric field in good agreement with our theoretical results for the effective dielectric tensor of VADHFLCs.