Morphological studies of a (self-assembling oil gelator/liquid crystal) composite system

The aggregation structure of a novel (self-assembling oil gelator/liquid crystal) composite was investigated using light scattering studies and morphological observations. The oil gelator forms a self-assembled-networks aggregate in an organic solvent with a low molecular weight liquid crystal (LC). It became apparent from Hv light scattering patterns and polarizing optical microscopy that two types of LC molecular alignments exist in the composite: a random orientation and a spherulite type one in a nematic gel state. Also, optical and atomic force microscopic observations revealed that fibrils which formed bundles in the fibre-like and spherulite-like aggregates, were formed in the composite. The alignment of the liquid crystal molecules was related to the aggregation structure of the self-assembling oil gelator in a liquid crystal gel state.     

Thermal switching characteristics based on smectic-A↔chiral nematic phase transitions of (liquid crystals/chiral dopant) composites,with and without side chain-type liquid crystalline polymer

The light switching characteristics induced by a thermal smectic A (SmA) ? chiral nematic (N*) phase transition were studied for homeotropically aligned [smectic A liquid crystal (SmA-LC)/nematic liquid crystal (N-LC)/chiral dopant] and [side chain type smectic A liquid crystalline polymer (SmA-LCP)/N-LC/chiral dopant] composites. A drastic change from a transparent SmA phase to a light-scattering N* phase occurred in both composites upon heating. In the case of the heat-induced N* phase for the (SmA-LC/N-LC/chiral dopant) composite, the N* phase exhibited weak light scattering due to formation of a scroll texture. On the other hand, in the case of the heat-induced N* phase for the (SmA-LCP/N-LC/chiral dopant) composite, the N* phase showed strong light scattering due to formation of a focalconic texture. The existence of a SmA-LCP was responsible for a higher contrast ratio between the transparent SmA phase and the light scattering N* phase for the (SmA-LCP/ N-LC/chiral dopant) composite than for the (SA-LCN/N-LC/chiral dopant) composite.     

Practical synthesis of 4′-selenopyrimidine nucleosides using hypervalent iodine

We report herein a synthesis of 4′-selenouridine 12 and 4′-selenocytidine 14, substrates for the synthesis of 4′-selenoRNA. The Pummerer-like reaction between the selenoxide 9 and a silylated uracil afforded the desired 4′-selenouridine derivative 10; however, the chemical yield of 10 was rather low. In addition, the reproducibility of this reaction was poor because of the instability of the selenoxide 9. Improvement of this Pummerer-like reaction to give 10 was achieved when the 4-selenosugar 8 was treated with TMSOTf, 2,6-lutidine and the silylated uracil in the presence of iodosylbenzene.     

Improved resolution for aerial imaging by retro-reflection with two transparent spheres

Optical Review - This paper proposes a method to improve the modulation transfer function (MTF) of aerial images by combining an aerial imaging optical system by retro-reflection with conjugated...