Photoinduced optical anisotropy (PIA) in condensed media - nature, properties, applications.100 anniversary of weigert effect

In 1919 F. Weigert published a paper on an effect detected by him. In solid solutions of complex molecules of organic dyes induced anisotropy of optical properties appeared under ecitation by polarized light. This paper stimulated investigation of anisotropy of different materials by optical methods. Significant results have been obtained for data on anisotropy of primary processes of light radiation and absorption that relate to specific features of intermolecular interaction in condensed matter. The effect is used in holography, integrated, fiber and polarization optics, in systems for information recording, storage, processing and displaying

Nanomesh aluminum films for LC alignment : theoretical and experimental modeling

A porous system for LC alignment is reviewed. Fabrication of nanomesh aluminum films and their porous structure are described. Methods of the nanomesh parameters for optimal LC alignment are discussed. A model of the LC alignment in a porous system is proposed. The LC orientation type is determined by the free anchoring energy and the micropore diameter. The difference between planar and homeotropic anchoring energies appears to be lower than the interaction energy by two orders of magnitude

Some New Reactions and Properties of Xanthane Hydride (5-Amino-1,2,4-dithiazole-3-thione)

Aminomethylation of xanthane hydride (5-amino-1,2,4-dithiazole-3-thione) with the RNH2–HCHO system has resulted in the formation of the derivatives of new heterocyclic system (3,7-dihydro-5H-[1,2,4]-dithiazolo[4,3-a][1,3,5]triazine) in low yields. The reaction of xanthane hydride with dicyandiamide has led to thioammeline [4,6-diamino-1,3,5-triazine-2(5Н)-thione]. Some practically important properties of xanthane hydride and its derivatives have been investigated. Xanthane hydride has efficiently exhibited carbon steel corrosion in neutral aqueous media. The prepared compounds have not exhibited growth-regulating or antidote activity to herbicide 2,4-D

Novel Biocompatible with Animal Cells Composite Material Based on Organosilicon Polymers and Fullerenes with Light-Induced Bacteriostatic Properties

A technology for producing a nanocomposite based on the borsiloxane polymer and chemically unmodified fullerenes has been developed. Nanocomposites containing 0.001, 0.01, and 0.1 wt% fullerene molecules have been created. It has been shown that the nanocomposite with any content of fullerene molecules did not lose the main rheological properties of borsiloxane and is capable of structural self-healing. The resulting nanomaterial is capable of generating reactive oxygen species (ROS) such as hydrogen peroxide and hydroxyl radicals in light. The rate of ROS generation increases with an increase in the concentration of fullerene molecules. In the absence of light, the nanocomposite exhibits antioxidant properties. The severity of antioxidant properties is also associated with the concentration of fullerene molecules in the polymer. It has been shown that the nanocomposite upon exposure to visible light leads to the formation of long-lived reactive protein species, and is also the reason for the appearance of such a key biomarker of oxidative stress as 8-oxoguanine in DNA. The intensity of the process increases with an increase in the concentration of fullerene molecules. In the dark, the polymer exhibits weak protective properties. It was found that under the action of light, the nanocomposite exhibits significant bacteriostatic properties, and the severity of these properties depends on the concentration of fullerene molecules. Moreover, it was found that bacterial cells adhere to the surfaces of the nanocomposite, and the nanocomposite can detach bacterial cells not only from the surfaces, but also from wetted substrates. The ability to capture bacterial cells is primarily associated with the properties of the polymer; they are weakly affected by both visible light and fullerene molecules. The nanocomposite is non-toxic to eukaryotic cells, the surface of the nanocomposite is suitable for eukaryotic cells for colonization. Due to the combination of self-healing properties, low cytotoxicity, and the presence of bacteriostatic properties, the nanocomposite can be used as a reusable dry disinfectant, as well as a material used in prosthetics

Influence of the order parameter on the anchoring energy of liquid crystals

No theory of the polar and azimuthal anchoring energies of liquid crystals (LCs) has been developed on a molecular level, despite the scientific and practical topicality of the problem. The interaction energies of mesogenic molecules with graphite and polyethylene surfaces calculated previously by the method of atom-atom potentials are in good agreement with the experimental data, but, at the same time, the calculated polar and azimuthal anchoring energies are larger than their experimental values by one and two orders of magnitude, respectively. To explain these values, the anchoring energy has been assumed to depend not only on the interaction with the surface but also on the interaction between the LC molecules arranged in the model in the form of quasi-layers. The mesogenic molecules have been modeled by rods with virtual C' atoms (carbon atoms with hydrogen atoms attached to them) "threaded" on them. The molecule orientation has been specified by the polar and azimuthal angles theta (i) , phi (i) and theta (j) , phi (j) relative to the directors of the ith and jth layers. The derived polar and azimuthal anchoring energies as well as their dependences on the order parameter have turned out to be close to the experimental data

Anchoring Energy of Liquid Crystals

The liquid crystals anchoring theory is considered on the molecular level. Earlier calculations of mesogenic molecules interaction energy with graphite and PE surface give results being one-two orders higher than experimentally obtained values. To explain the experimental values of anchoring energy we proposed its dependence on the interaction between liquid crystal layers. In our calculations we have simulated the mesogen molecules by virtual rod-like molecules. The molecules orientation was given by polar and azimuthal angles towards the directors of neighboring liquid crystal layers. Obtained values of polar and azimuthal anchoring energy as well as their dependences on the order parameter are in good agreement with experimental data