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Pozhidaev E.P.,Hong Kong University of Science and Technology | Srivastava A.K.,Hong Kong University of Science and Technology | Kiselev A.D.,Hong Kong University of Science and Technology | Kiselev A.D.,Ukrainian Academy of Sciences | And 5 more authors.
Optics Letters | Year: 2014

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 2φ has been obtained at subkilohertz frequency. © 2014 Optical Society of America.


Prodanov M.F.,State Scientific Institution Institute for Single Crystals | Buluy O.G.,Ukrainian Academy of Sciences | Popova E.V.,State Scientific Institution Institute for Single Crystals | Gamzaeva S.A.,State Scientific Institution Institute for Single Crystals | And 2 more authors.
Soft Matter | Year: 2016

We report the development of a highly stable nanomaterial based on ferromagnetic nanoparticles dispersed in a thermotropic liquid crystal. The long-term colloidal stability and homogeneity were achieved through surface modification of the nanoparticles with a mixture of a dendritic oligomesogenic surfactant and hexylphosphonic acid and confirmed by optical and electron microscopy. The nanomaterial has an increased sensitivity to the magnetic field possessing collective and non-collective magneto-optical responses in contrast to the undoped LC. The effective coupling of the spherical particles with the LC director is due to the arrangement of the nanoparticles in chains. © 2016 The Royal Society of Chemistry.


Pozhidaev E.P.,Hong Kong University of Science and Technology | Minchenko M.,RAS Lebedev Physical Institute | Molkin V.,RAS Lebedev Physical Institute | Torgova S.,RAS Lebedev Physical Institute | And 5 more authors.
SID Conference Record of the International Display Research Conference | Year: 2011

Newly developed ferroelectric liquid crystal (FLC) with submicron helix pitch p 0 comprises advantages of both nematic and smectic C*phases in terms of steadiness to the mechanical stress and high contrast ratio more than 7000:1 at the operation frequency range up to 1 kHz with ±IV/μm applied electric field.


Varchenko V.,State Scientific Institution Institute for Single Crystals | Bryleva E.Y.,State Scientific Institution Institute for Single Crystals | Belikov K.N.,State Scientific Institution Institute for Single Crystals | Kalchenko V.I.,Ukrainian Academy of Sciences
Journal of the Electrochemical Society | Year: 2014

Electrochemical behavior of vinpocetine at a plain carbon paste electrode and paste electrodes modified with different calixarenes and ammonium metavanadate was studied by means of cyclic and differential pulse voltammetry. The effect of pH and scan rate on the response at both plain and modified carbon paste electrodes has been revealed. Modification of an electrode with a mixture of ammonium metavanadate and some calixarenes led to considerable decrease of background current along with sensitivity increase as compared to an unmodified carbon paste electrode or an electrode modified with calixarenes only. For the most effective electrode composition, the linear working range was shown to be 2.10-8-6.10-6 M with a detection limit of 5.10-9M. © 2014 The Electrochemical Society.


Buluy O.,Ukrainian Academy of Sciences | Burseva D.,Ukrainian Academy of Sciences | Hakobyan M.R.,Yerevan State University | Goodby J.W.,University of York | And 6 more authors.
Molecular Crystals and Liquid Crystals | Year: 2012

We observe a strong effect of surfactant structure on the aggregation of ferromagnetic nanoparticles in nematic liquid crystal (LC) hosts, and the colloidal stability and ordering of the resulting nematic matrix. We find that ferromagnetic nanoparticles coated with surfactants that possess terminal mesogenic groups induce minimal aggregation of the nanoparticles, resulting in a 1.5 times reduction in the value of the Frederikscz transition field in comparison with the parent LC host. Copyright © 2012 Taylor and Francis Group, LLC.


Kharchenko V.O.,Institute of Applied Physics | Kharchenko V.O.,State Scientific Institution Institute for Single Crystals | Kharchenko V.O.,Sumy State University | Kharchenko D.O.,Institute of Applied Physics | And 14 more authors.
Nanosistemi, Nanomateriali, Nanotehnologii | Year: 2015

We study processes of pyramidal-structures' formation during epitaxial growth within the framework of the phase-field theory by taking into account interactions of adsorbate. In the case of constant surface temperature, fluctuations of the total flux of adsorbate are introduced. As shown, the pyramidal structures can be formed at elevated values of interaction energy for adsorbate. Dependences of the lateral correlation length on the control parameters are computed. As found, an increase in the multiplicative-noise intensity leads to formation of patterns with a needle-like structure. As shown within the framework of the generalized phase-field model by taking into account local change in the surface temperature during adsorption-desorption processes, at early stages of the system evolution, the oscillation regime of pattern formation is realized. As revealed, the frequency of temperature oscillations increases with the depositionrate growth. As found within the generalized model, pyramidal structures are characterized by large differences in heights between two neighbour terraces and can be formed at low values of interaction energy for adsorbate. Surface growth indicator and roughness exponents are obtained. As determined, the mean number of adsorbate islands grows in time by the power law, and the mean area of pyramidal structures falls down in time by the power law with the same absolute value of exponent. Distributions of adsorbate islands over sizes are studied in detail. An estimation of the mean linear size of adsorbate clusters gives (R) = 100-400 nm. Within the framework of the generalized kinetic approach, a theoretical model for the island-size dynamics manifesting the self-similar behaviour and universality of the probability density over the island sizes is proposed. © 2015.


Petrova O.N.,State Scientific Institution Institute for Single Crystals | Zamigajlo L.L.,State Scientific Institution Institute for Single Crystals | Ostras K.S.,State Scientific Institution Institute for Single Crystals | Shishkina S.V.,State Scientific Institution Institute for Single Crystals | And 8 more authors.
Chemistry of Heterocyclic Compounds | Year: 2015

[Figure not available: see fulltext.] Three-component reactions of 2-aminobenzimidazole with arylglyoxals and 1,3-cyclohexanedione have been studied under conventional heating and microwave irradiation. Different product types including the Michael adduct and fused heterocyclic systems were obtained. Conditions for the selective formation of 12-aroylbenzimidazo[2,1-b]quinazolin-1(2H)-ones and 3-oxo-2-(2-aryl-1H-imidazo[1,2-a]-benzimidazol-9-ium-3-yl)cyclohex-1-enolates have been determined. The structures of all compound types were established by an X-ray diffraction study. © 2015 Springer Science+Business Media New York

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