Interplay between dipole and quadrupole modes of field influence in liquid-crystalline suspensions of ferromagnetic particles

In the framework of continuum theory we study orientational transitions induced by electric and magnetic fields in ferronematics, i.e., in liquid-crystalline suspensions of ferromagnetic particles. We have shown that in a certain electric field range the magnetic field can induce a sequence of re-entrant orientational transitions in ferronematic layer: nonuniform phase --- uniform phase --- nonuniform phase. This phenomenon is caused by the interplay between the dipole (ferromagnetic) and quadrupole (dielectric and diamagnetic) mechanisms of the field influence on a ferronematic structure. We have found that these re-entrant Freedericksz transitions exhibit tricritical behavior, i.e., they can be of the first or the second order. The character of the transitions depends on a degree of redistribution of magnetic admixture in the sample exposed to uniform magnetic field (magnetic segregation). We demonstrate how electric and magnetic fields can change the order of orientational transitions in ferronematics. We show that electric Freedericksz transitions in ferronematics subjected to magnetic field have no re-entrant nature. Tricritical segregation parameters for the transitions induced by electric or magnetic fields are obtained analytically. We demonstrate the re-entrant behavior of ferronematic by numerical simulations of the magnetization and optical phase lag.Comment: 12 pages, 9 figures, to be published in Soft Matte

New fast-relaxed liquid crystal materials for optical communication networks

Recording the dynamic holograms with microsecond relaxation times under action of laser pulses was obtained in composites based on the novel class of liquid crystals (LC), namely in ionic metal-alkanoates. Holographic parameters of the recording and relaxation characteristics were studied for doped lyotropic ionic LC and sandwich-like cells with photo-sensitive impurities for purposes of real-time dynamic holography applications. The thin cells demonstrate high-velocity dynamic grating recording under laser pulses both of nanosecond and picosecond durations at the visible wavelengths. The cells exhibit a fast temperature relaxation time (with the time constant 30 μs for the store heat density more than 50 kJ/s). Ionic lyotropic smectic LCs possess a high intrinsic anisotropic conductivity as compared with other LCs – dielectrics. To explain the relaxation mechanisms in ionic smectic LC matrix, the temperature dependences of the electro-conductivity have been investigated. The charge currier mobility and activation energy in cells were estimated. The mechanism of high-velocity resonance nonlinearity due to the saturation of excited states in photosensitive centers and mechanisms of the grating erasure connected with charge transport in the ionic LC matrix were discussed

Nanomaterials in Liquid Crystals as Ion-Generating and Ion-Capturing Objects

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this paper, a recently developed model of contaminated nanomaterials in liquid crystals is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed

Kinetics of Ion-Capturing/Ion-Releasing Processes in Liquid Crystal Devices Utilizing Contaminated Nanoparticles and Alignment Films

Various types of nanomaterials and alignment layers are considered major components of the next generation of advanced liquid crystal devices. While the steady-state properties of ion-capturing/ion-releasing processes in liquid crystals doped with nanoparticles and sandwiched between alignment films are relatively well understood, the kinetics of these phenomena remains practically unexplored. In this paper, the time dependence of ion-capturing/ion-releasing processes in liquid crystal cells utilizing contaminated nanoparticles and alignment layers is analyzed. The ionic contamination of both nanodopants and alignment films governs the switching between ion-capturing and ion-releasing regimes. The time dependence (both monotonous and non-monotonous) of these processes is characterized by time constants originated from the presence of nanoparticles and films, respectively. These time constants depend on the ion adsorption/ion desorption parameters and can be tuned by changing the concentration of nanoparticles, their size, and the cell thickness

On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals

Nanomaterials in liquid crystals are a hot topic of contemporary liquid crystal research. An understanding of the possible effects of nanodopants on the properties of liquid crystals is critical for the development of novel mesogenic materials with improved functionalities. This paper focuses on the electrical behavior of contaminated nanoparticles in liquid crystals. More specifically, an analogy between electrolytes and ion-generating nanomaterials in liquid crystals is established. The physical consequences of this analogy are analyzed. Under comparable conditions, the number of ions generated by nanomaterials in liquid crystals can be substantially greater than the number of ions generated by electrolytes of similar concentration

La traductologie russe de la Révolution d’Octobre à la Russie post-soviétique

Research into Russian traductology of the 20th century has been conducted abroad, notably in French-speaking countries. It began with a phase dominated by an empirical approach ; the first theoretical text, written by Tchoukovsky and Goumiliov, appeared in 1919. Russian traductology proper only began with the work of Fedorov, Kachkin and Komissarov. It was marked by a programmatic intention emanating at first from Gorki, who thought that a theory of literary translation would assist in the education of the masses. Later, Russian traductology became the preserve of the universities, and was brought under state control. After the 2nd World War Russian theories of translation became broader, with linguistics playing a leading role. Questions of of translatibility and equivalence came to dominate the field. The soviet school of interpreration developed in parallel during the 1940s, inspired by the likes of Goffman, Minjar-Belorutchev and Tchernov. We can thus affirm that a recognisably soviet traductology was present throughout most of the 20th century.La traductologie russe du XXe siècle a été étudiée à l’étranger, notamment dans l’univers francophone. Elle commence par un stade empirique et le premier texte théorique verra le jour en 1919 sous la plume de Tchoukovsky et Goumiliov. Il faudra attendre les travaux de Fedorov, de Kachkin et de Komissarov pour qu’elle acquière une dimension proprement traductologique. Elle a été marquée par une volonté programmatique décidée dans un premier temps par Gorki qui souhaitait une théorie de la traduction littéraire, afin d’éduquer les masses populaires. Plus tard, la traductologie russe se développera exclusivement dans le contexte universitaire et sous le contrôle de l’État. Après la Seconde guerre mondiale, la théorie russe de la traduction s’élargira à une conception généraliste où la linguistique occupera une place prépondérante. Ce sont les soucis de traduisibilité et d’équivalence qui dominent alors les débats. Parallèlement, se développera dans les années 1940 l’école soviétique d’interprétation, incarnée par des figures de proue comme Goffman, Minjar-Belorutchev ou Tchernov. On peut donc affirmer l’existence d’une véritable traductologie soviétique qui coïncide avec la majeure partie du XXe siècle.Garbovskiy Nikolay. La traductologie russe de la Révolution d’Octobre à la Russie post-soviétique. In: Équivalences, 43e année-n°1-2, 2016. pp. 31-86

Un siècle de traductologie russe

La période de l’histoire de la traductologie russe que je voudrais envisager s’étend sur cent ans (de la révolution russe de 1917 à nos jours), il s’agit donc de l’histoire contemporaine de la pensée traductologique. Lors de l’histoire séculaire de la traductologie, trois courants de recherches, avec la prédominance littéraire, linguistique, ou interdisciplinaire, se succèdent, ce qui nous permet de voir des traits similaires dans l’évolution de la pensée traductologique russe et celle des pays occidentaux

Ion-Generating and Ion-Capturing Nanomaterials in Liquid Crystals

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this presentation, a recently developed model of contaminated nanomaterials is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed