Light modulation characteristics of a single-polarizer electro-optical cell based on polymer dispersed ferroelectric liquid crystals

Features of the light passing through a single-polarizer electro-optical cell based on a uniaxially oriented film of a polymer dispersed ferroelectric liquid crystal have been studied. The optical response as a function of the applied electric field is shown to depend on the cell geometry. A detailed analysis is presented of the dependence of the maximum light transmission, modulation depth and contrast ratio on the angle between the light polarization and the film orientation direction, on its optical anisotropy and on the molecular tilt angle. An approximate formula is proposed to estimate the highest attainable contrast. Parameters under study have been measured for PDFLC films varying in optical anisotropy value. The experimental results prove to be in good agreement with theoretical estimations.     

Friedericksz threshold field in bipolar nematic droplets with strong surface anchoring

A numerical method has been developed for calculating the director configuration in ellipsoidal droplets of a nematic liquid crystal with strong tangential anchoring in a uniform magnetic field of an arbitrary orientation. A relation has been obtained for determining the Friedericksz threshold corresponding to the beginning of the reorientation of the central region of a droplet when the field is orthogonal to the biopolar axis. The effect of the breaking of the orthogonal condition on the threshold character of the orientation process is considered. The reorientation of the ensemble of bipolar droplets of the 5CB nematic liquid crystal dispersed in polyvinyl butyral has been studied by the magneto-optical method. Comparative analysis of calculation data and measured values of the threshold field has been performed.     

Ceric ammonium nitrate (CAN) catalyzed synthesis and α-glucosidase activity of some novel tetrahydropyridine phosphonate derivatives

Abstract

A simple and highly efficient multicomponent one-pot synthesis of a series of pharmaceutically interesting functionalized tetrahydropyridine phosphonate derivatives has been developed based on low-cost and environmentally benign ceric ammonium nitrate (CAN) catalyst via tandem reactions of 1,3-dicarbonyl compounds, diethylphosphoramidate and various aromatic aldehydes in acetonitrile at room temperature. High atom economy, good yields, eco-friendliness and mild reaction conditions are some of the important features of this protocol.     

5-Aryl-2,2′-bipyridines bearing fluorinated anilines residues at C6 position: synthesis and photophysical properties

Research on Chemical Intermediates - A convenient synthetic approach to 5-aryl-2,2′-bipyridines bearing a (poly)fluorine-containing aniline residue at position C6 based on sequential...     

Investigation of a stainless-steel surface irradiated with protons in an iodine medium

The surface of 1Cr18Ni10Ti stainless steel irradiated by protons with an energy of 5.7 MeV in an iodine medium is studied by Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS). Iodine bonded with oxygen and molecular I₂ is observed in a thin 10-nm-thick steel surface layer. Iodine depth profiles are obtained using the RBS and XPS spectra. The possibility of the formation of chemical compounds containing iodine on the steel surface with allowance for the proton-irradiation effect on iodine adsorption is discussed.     

Orientational changes in the nematic liquid crystal structure on a polymer surface induced by phase separation in a magnetic field

The change in the domain texture of the 5CB nematic liquid crystal on the surface of a polyvinyl butyral gelatinous polymer solution cured in a magnetic field is studied optically. The alignment of the nematic is described by the effective order parameter S* of the polydomain cells. The anchoring energy of a liquid crystal with gelatinous polymer W _ϕ = 1 × 10⁻³ erg/cm₂ is determined.     

X-Ray Diffraction Study of 8-(Pyridin-2-yl)- and 8-(1,2,4-Triazin-5-yl)-2H-chromen-2-ones

Russian Journal of General Chemistry - The molecular and crystal structures of 8-(3,6-diphenylpyridin-2-yl)-5,7-dimethoxy-4-phenyl-2H-chromen-2-one,...     

5-Aryl-6-arylthio-2,2′-bipyridine and 6-Arylthio-2,5-diarylpyridine Fluorophores: Pot,Atom, Step Economic (PASE) Synthesis and Photophysical Studies

Journal of Fluorescence - A PASE (pot, step, atom, economic) synthetic approach to 5-aryl-6-arylthio-2,2′-bipyridine and 6-arylthio-2,5-diarylpyridine ligands/fluorophores has been reported...