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Sample records for ternary liquid crystals

  1. Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Klaus Mann

    2009-11-01

    Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.

  2. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  3. Liquid-liquid equilibria for ternary polymer mixtures

    Science.gov (United States)

    Oh, Suk Yung; Bae, Young Chan

    2011-01-01

    A molecular thermodynamic model for multicomponent systems based on a closed-packed lattice model is presented based on two contributions; entropy and energy contribution. The calculated liquid-liquid equilibria of ternary chainlike mixtures agreed with Monte Carlo simulation results. The proposed model can satisfactorily predict Types 0, 1, 2 and 3 phase separations of the Treybal classification. The model parameters obtained from the binary systems were used to directly predict real ternary systems and the calculated results correlated well with experimental data using few adjustable parameters. Specific interactions in associated binary systems were considered using a secondary lattice.

  4. Liquid-liquid equilibria for ternary polymer mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Suk Yung [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133-791 (Korea, Republic of); Bae, Young Chan, E-mail: ycbae@hanyang.ac.kr [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2011-01-24

    Graphical abstract: We developed a molecular thermodynamic model for multicomponent systems and discribed the phase equilibrium for ternary polymer mixtures by using the model parameters obtained from the binary systems. Research highlights: {yields} Model parameters were obtained from the binary systems. {yields} The obtained parameters were directly used to predict the ternary data. {yields} The undetermined parameters were used to correlate the ternary data. {yields} The proposed model agreed well with the experimental data. - Abstract: A molecular thermodynamic model for multicomponent systems based on a closed-packed lattice model is presented based on two contributions; entropy and energy contribution. The calculated liquid-liquid equilibria of ternary chainlike mixtures agreed with Monte Carlo simulation results. The proposed model can satisfactorily predict Types 0, 1, 2 and 3 phase separations of the Treybal classification. The model parameters obtained from the binary systems were used to directly predict real ternary systems and the calculated results correlated well with experimental data using few adjustable parameters. Specific interactions in associated binary systems were considered using a secondary lattice.

  5. Phase field crystal modeling of ternary solidification microstructures

    OpenAIRE

    Berghoff, Marco; Nestler, Britta

    2015-01-01

    In the present work, we present a free energy derivation of the multi-component phase-field crystal model [1] and illustrate the capability to simulate dendritic and eutectic solidification in ternary alloys. Fast free energy minimization by a simulated annealing algorithm of an approximated crystal is compared with the free energy of a fully simulated phase field crystal structure. The calculation of ternary phase diagrams from these free energies is described. Based on the free energies rel...

  6. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium.......We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  7. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Sabine Laschat; Axenov, Kirill V

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  8. Liquid Crystal Airborne Display

    Science.gov (United States)

    1977-08-01

    with the drive capability of the present state-of-the- art microm.ziiaturized integi ated circuits. The impact of microminiaturizing the drive circuits...7 Advantages /Disadvantages of Prior Art .........- 8 Performance of the Liquid Crystal Matrix Display . . .. 8 Liquid Crystal...Holographic HUD Light Source ...................... .... 99 Design of a Special Purpose Mercury Art - Plo.?hcr La np . 104 V LARGE SCALE INTEGRATION FOR DISPLAY

  9. Liquid-liquid equilibria for binary and ternary polymer solutions with PC-SAFT

    DEFF Research Database (Denmark)

    Lindvig, Thomas; Michelsen, Michael Locht; Kontogeorgis, Georgios

    2004-01-01

    are used for investigating the correlative and predictive capabilities of the thermodynamic model PC-SAFT. The investigation shows that the model correlates well experimental LLE data for binary as well as ternary systems but further predicts the behavior of the ternary systems with reasonably good......Two algorithms for evaluating liquid-liquid equilibria (LLE) for binary and ternary polymer solutions are presented. The binary algorithm provides the temperature versus concentration cloud-point curve at fixed pressure, whereas the ternary algorithm provides component 1 versus component 2...

  10. Dynamic light scattering and viscosity measurements in a ternary and quaternary discotic lyotropic nematic liquid crystal: Tuning the backflow with salt

    Science.gov (United States)

    Risi, C. L. S.; Figueiredo Neto, A. M.; Akpinar, E.; Santos, M. B. Lacerda

    2013-08-01

    Using a dynamic light scattering technique, we measure the damping rate of thermal fluctuations of the nematic director for the so-called disklike nematic ND phase of both the ternary lyotropic K-laurate-1-decanol-H2O system and the quaternary one of similar composition except for the addition of salt (K2SO4). By varying the scattering angle in suitable geometries and polarizations, we are able to measure the orientational diffusivities associated with the pure deformations of splay and twist. A previous study made in the ND phase of the same ternary system yielded a large deviation between the splay and twist diffusivities. The effect was then interpreted in terms of the anisotropy between their associated viscosities due to induced flows, or backflow. In the present work we observe a strong increase of the backflow as an effect of the added salt. In addition, we make auxiliary measurements of shear viscosity and magnetic instabilities, which help to characterize the effect of the salt in the orientational diffusivities as they are mixed quantities involving elastic constants and viscosity coefficients.

  11. Liquid crystals fundamentals

    CERN Document Server

    Singh, Shri

    2001-01-01

    Liquid crystals are partially ordered systems without a rigid, long-range structure. The study of these materials covers a wide area: chemical structure, physical properties and technical applications. Due to their dual nature - anisotropic physical properties of solids and rheological behavior of liquids - and easy response to externally applied electric, magnetic, optical and surface fields liquid crystals are of greatest potential for scientific and technological applications. The subject has come of age and has achieved the status of being a very exciting interdisciplinary field of scienti

  12. Studies on Molecular Interaction in Ternary Liquid Mixtures

    Directory of Open Access Journals (Sweden)

    R. Uvarani

    2010-01-01

    Full Text Available Ultrasonic velocity, density and viscosity for the ternary liquid mixtures of cyclohexanone with 1-propanol and 1-butanol in carbon tetrachloride were measured at 303 K. The acoustical parameters and their excess values were calculated. The trends in the variation of these excess parameters were used to discuss the nature and strength of the interactions present between the component molecules.

  13. Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment

    Science.gov (United States)

    Su, Ching-Hua

    2014-01-01

    A low gravity material experiment will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). There are two sections of the flight experiment: (I) crystal growth of ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, by physical vapor transport (PVT) and (II) melt growth of CdZnTe by directional solidification. The main objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the grown crystals as results of buoyancy-driven convection and growth interface fluctuations caused by irregular fluid-flows on Earth. The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent flight experimentation. This talk will focus on the ground-based studies on the PVT crystal growth of ZnSe and related ternary compounds. The objectives of the ground-based studies are (1) obtain the experimental data and conduct the analyses required to define the optimum growth parameters for the flight experiments, (2) perfect various characterization techniques to establish the standard procedure for material characterization, (3) quantitatively establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the crystals grown in a low-gravity environment and (4) develop theoretical and analytical methods required for such evaluations. ZnSe and related ternary compounds have been grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals have been characterized extensively by various techniques to correlate the grown crystal properties with the growth conditions.

  14. Liquid crystals in tribology.

    Science.gov (United States)

    Carrión, Francisco-José; Martínez-Nicolás, Ginés; Iglesias, Patricia; Sanes, José; Bermúdez, María-Dolores

    2009-09-18

    Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs), only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs). Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.

  15. Liquid crystal dimers

    CERN Document Server

    Kumar Pal, Santanu

    2017-01-01

    This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

  16. Liquid crystal colloids

    CERN Document Server

    Muševič, Igor

    2017-01-01

    This book brings together the many concepts and discoveries in liquid crystal colloids contributed over the last twenty years and scattered across numerous articles and book chapters. It provides both a historical overview of the development of the field and a clear perspective on the future applications in photonics. The book covers all phenomena observed in liquid crystal colloids with an emphasis on experimental tools and applications of topology in condensed matter, as well as practical micro-photonics applications. It includes a number of spectacular manifestations of new topological phenomena not found or difficult to observe in other systems. Starting from the early works on nematic colloids, it explains the basics of topological defects in ordered media, charge and winding, and the elastic forces between colloidal particles in nematics. Following a detailed description of experimental methods, such as optical tweezing and particle tracking, the book eases the reader into the theoretical part, which de...

  17. Pyrrolidinium Ionic Liquid Crystals

    OpenAIRE

    Goossens, Karel; Lava, Kathleen; Nockemann, Peter; Van Hecke, Kristof; Van Meervelt, Luc; Driesen, Kris; Görller-Walrand, Christiane; Binnemans, Koen; Cardinaels, Thomas

    2009-01-01

    N-Alkyl-N-methylpyrrolidinium cations have been used for the design of ionic liquid crystals, including a new type of uranium-containing metallomesogen. Pyrrolidinium salts with bromide, bis(trifluoromethylsulfonyl)-imide, tetrafluoroborate, hexafluorophosphate, thiocyanate, tetrakis(2-thenoyltrifluoroacetonato)europate(III) and tetrabromouranyl] counteranions were prepared. For the bromide salts and tetrabromouranyl compounds, the chain length of the alkyl group CnH2n+1 was varied from eight...

  18. Instabilities in liquid crystals

    CERN Document Server

    Barclay, G J

    1998-01-01

    and we examine the differences which occur for differing dielectric anisotropies. Finally, in Chapter 7 we study how a sample of smectic C liquid crystal behaves when it is subjected to a uniform shear flow within the smectic plane. We find travelling wave solutions for the behaviour of the c-director and adapt these solutions to incorporate the effects of an applied field. This thesis contains theoretical work dealing with the effects of magnetic and electric fields on samples of nematic, smectic A and smectic C liquid crystals. Some background material along with the continuum theory is introduced in Chapter 2. In Chapter 3 we consider the effect on the director within an infinite sample of nematic liquid crystal which is subjected to crossed electric and magnetic fields. In particular we examine the stability of the travelling waves which describe the director motion by considering the behaviour of the stable perturbations as time increases. The work of Chapter 4 examines a bounded sample of smectic A liqu...

  19. Crystal growth and property characterization for PIN–PMN–PT ternary piezoelectric crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-01-01

    Full Text Available Binary piezoelectric crystal Pb(Mg1/3Nb2/3O3–PbTiO3 (PMN–PT has excellent dielectric and piezoelectric properties, which has led to the commercialization for medical ultrasound imaging. Recently, there is a growing demand for piezoelectric crystals with improved thermal and electrical properties. Ternary piezoelectric crystals Pb(In1/2Nb1/2O3–Pb(Mg1/3Nb2/3O3–PbTiO3 (PIN–PMN–PT have increased depoling temperature and coercive field than binary PMN–PT. To better understand the ternary crystal system and improve crystal properties, we systematically investigated crystal growth of PIN–PMN–PT with modified Bridgman method. Like PMN–PT, PIN–PMN–PT crystals have excellent piezoelectric properties (e.g., k33 ~ 0.87–0.92, d33 ~ 1000–2200 pm/V. Higher PIN content leads to ~40°C increase in depoling temperature and more than doubling of coercive field(~7.0 kV/cm. Such improvements are advantageous for applications where high temperature and/or high-drive are needed.

  20. Analysis of liquid crystal properties for photonic crystal fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2009-01-01

    We analyze the bandgap structure of Liquid Crystal infiltrated Photonic Crystal Fibers depending on the parameters of the Liquid Crystals by means of finite element simulations. For a biased Liquid Crystal Photonic Crystal Fiber, we show how the tunability of the bandgap position depends...

  1. Nanoparticles Doped, Photorefractive Liquid Crystals

    National Research Council Canada - National Science Library

    Kaczmarek, Malgosia

    2005-01-01

    ...: The main objectives of this exploratory, short project will concern the study of the quality of liquid crystal cells with diluted suspensions of ferroelectric nanoparticles and their photorefractive properties...

  2. Adaptive Liquid Crystal Windows

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31

    Energy consumption by private and commercial sectors in the U.S. has steadily grown over the last decade. The uncertainty in future availability of imported oil, on which the energy consumption relies strongly, resulted in a dramatic increase in the cost of energy. About 20% of this consumption are used to heat and cool houses and commercial buildings. To reduce dependence on the foreign oil and cut down emission of greenhouse gases, it is necessary to eliminate losses and reduce total energy consumption by buildings. To achieve this goal it is necessary to redefine the role of the conventional windows. At a minimum, windows should stop being a source for energy loss. Ideally, windows should become a source of energy, providing net gain to reduce energy used to heat and cool homes. It is possible to have a net energy gain from a window if its light transmission can be dynamically altered, ideally electronically without the need of operator assistance, providing optimal control of the solar gain that varies with season and climate in the U.S. In addition, the window must not require power from the building for operation. Resolution of this problem is a societal challenge and of national interest and will have a broad global impact. For this purpose, the year-round, allclimate window solution to provide an electronically variable solar heat gain coefficient (SHGC) with a wide dynamic range is needed. AlphaMicron, Inc. (AMI) developed and manufactured 1ft × 1ft prototype panels for the world’s first auto-adjusting Adaptive Liquid Crystal Windows (ALCWs) that can operate from sunlight without the need for external power source and demonstrate an electronically adjustable SHGC. This novel windows are based on AlphaMicron’s patented e-Tint® technology, a guesthost liquid crystal system implemented on flexible, optically clear plastic films. This technology is suitable both for OEM and aftermarket (retro-fitting) lamination to new and existing windows. Low level of

  3. Liquid Crystals for Laser Applications

    Science.gov (United States)

    1992-07-01

    Structures, Leonard Hill, Philadelphia, PA, 1984. 5. Gray, G. W., Ed., Thermotropic Liquid Crystals, Series (Critical Reports on Applied Chemistry, Vol. 22...crystal, Phys. Rev. A, 29, 297-307, 1984. 331. Khyzhniak, A., Odoulov, S., Reznikov, Yu., and Soskin , M., Dynamic hologram recording and phase conjugation

  4. [Are liquid crystals living organisms?].

    Science.gov (United States)

    Snelders, H A

    1997-01-01

    In 1888 the Austrian botanist F. Reinitzer made the observation that the solid compound cholesteryl-benzoate changes - when melting at 145.5 oC - into a cloudy liquid, that however, turns into a clear liquid at 178.5 oC and higher temperatures. The cloudy liquid seemed to be doubly refracting. Soon a number of these so-called 'liquid crystals' were discovered; in 1908 D. Vorländer, professor of organic chemistry at Halle, described more than 250 of these substances. It was O. Lehmann, professor of physics at Aachen (1885), Dresden (1888) and Karlsruhe (1889), who immediately after Reinitzer's observation began a systematic study of these liquid crystals. In The Netherlands the Amsterdam professor of physican chemistry H. W. Bakhuis Roozeboom was interested in liquid crystals, in particular because of their place in his phase system. F.M. Jaeger, at that time teaching chemistry in a secondary school in Zaandam (near Amsterdam) and working as an unpaid university lecturer at the Amsterdam university (by recommendation of Bakhuis Roozeboom), investigated liquid crystals (1906), as did a number of doctoral students (A.C. de Kock, 1903; A. Prins, 1907). At the university of Utrecht L.S. Ornstein, professor of physics, gave the study of liquid crystals a prominent place in his research programme. The discovery of liquid crystals, which seemed to be able to grow, move, divide, copulate, and so on, led to a discussion on the nature of these substances. Time and again Lehmann called them 'apparently living crystals', although without considering them as 'real living beings'. In his book Flüssige Kristalle und die Theorien des Lebens (1906), Lehmann proved to be an obvious adherent of the monistic views of the biologist E. Haeckel. Haeckel considered the existence of liquid crystals as proof of the unity between the inorganic and the organic world that he believed in so strongly. In his last book, Kristallseelen. Studien über das Anorganische Leben (1917), he considered

  5. Serpentine diffusion trajectories and the Ouzo effect in partially miscible ternary liquid mixtures

    NARCIS (Netherlands)

    Krishna, R.

    2015-01-01

    This work investigates the transient equilibration process when partially miscible ternary liquid mixtures of two different compositions are brought into contact with each other. Diffusional coupling effects are shown to become increasingly significant as the mixture compositions approach the

  6. Liquid - liquid equilibria of the water + butyric acid + decanol ternary system

    Directory of Open Access Journals (Sweden)

    S.I. Kirbaslar

    2006-09-01

    Full Text Available Liquid-liquid equilibrium (LLE data for the water + butyric acid + decanol ternary system were determined experimentally at temperatures of 298.15, 308.15 and 318.15 K. Complete phase diagrams were obtained by determining the solubility curve and the tie lines. The reliability of the experimental tie line data was confirmed with the Othmer-Tobias correlation. The UNIFAC method was used to predict the phase equilibrium of the system using the interaction parameters for groups CH3, CH2, COOH, OH and H2O determined experimentally. Distribution coefficients and separation factors were evaluated for the immiscibility region.

  7. Ternary liquid-liquid equilibria measurement for epoxidized soybean oil + acetic acid + water.

    Science.gov (United States)

    Cai, Shuang-Fei; Wang, Li-Sheng; Yan, Guo-Qing; Li, Yi; Feng, Yun-Xia; Linghu, Rong-Gang

    2012-01-01

    Liquid-liquid equilibria (LLE) data were measured for ternary system epoxidized soybean oil (ESO) + acetic acid + water at 313.15, 323.15 and 333.15 K, respectively. The consistency of the measured LLE data was tested, using Othmer-Tobias correlation and root-mean-square deviation (sigma) in mass fraction of water in the lower phase and average value of the absolute difference (AAD) between experimental mass fraction of epoxidized soybean oil in the upper phase and that calculated using Othmer-Tobias correlation.

  8. Crystallization, data collection and processing of the chymotrypsin–BTCI–trypsin ternary complex

    Energy Technology Data Exchange (ETDEWEB)

    Esteves, Gisele Ferreira; Teles, Rozeni Chagas Lima; Cavalcante, Nayara Silva; Neves, David; Ventura, Manuel Mateus [Laboratório de Biofísica, Instituto de Ciências Biológicas, Universidade de Brasília, 70910-900 Brasília-DF (Brazil); Barbosa, João Alexandre Ribeiro Gonçalves, E-mail: joao@lnls.br [Center for Structural Molecular Biology (CeBiME), Brazilian Synchrotron Light Laboratory (LNLS), CP 6192, 13083-970 Campinas-SP (Brazil); Freitas, Sonia Maria de, E-mail: joao@lnls.br [Laboratório de Biofísica, Instituto de Ciências Biológicas, Universidade de Brasília, 70910-900 Brasília-DF (Brazil)

    2007-12-01

    A ternary complex of the proteinase inhibitor (BTCI) with trypsin and chymotrypsin was crystallized and its crystal structure was solved by molecular replacement. A ternary complex of the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) with trypsin and chymotrypsin was crystallized by the sitting-drop vapour-diffusion method with 0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 6000 and 5%(v/v) 2-methyl-2,4-pentanediol as precipitant. BTCI is a small protein with 83 amino-acid residues isolated from Vigna unguiculata seeds and is able to inhibit trypsin and chymotrypsin simultaneously by forming a stable ternary complex. X-ray data were collected from a single crystal of the trypsin–BTCI–chymotrypsin ternary complex to 2.7 Å resolution under cryogenic conditions. The structure of the ternary complex was solved by molecular replacement using the crystal structures of the BTCI–trypsin binary complex (PDB code) and chymotrypsin (PDB code) as search models.

  9. (Vapour + liquid) equilibria of ternary systems with ionic liquids using headspace gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtarani, Babak [Chemistry and Chemical Engineering Research Center of Iran, P.O. Box 14335-186, Tehran (Iran, Islamic Republic of); Gmehling, Juergen, E-mail: gmehling@tech.chem.uni-oldenburg.d [Carl von Ossietzky Universitaet Oldenburg, Technische Chemie, D-26111 Oldenburg (Germany)

    2010-08-15

    (Vapour + liquid) equilibrium (VLE) data for the ternary systems (hexane + benzene), (hexane + cyclohexane), (benzene + cyclohexane), and (ethanol + water) with an ionic liquid as entrainer for extractive distillation were measured by headspace gas chromatography. As ionic liquids, 1-hexyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [HMIM][BTI], 1-octyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [OMIM][BTI], 1-octyl-3-methyl-imidazolium trifluoro-methanesulfonate [OMIM][OTF], and 1-butyl-3-methyl-imidazolium trifluoro-methanesulfonate [BMIM][OTF] were used. The experimental data show that the ionic liquids investigated have a great influence on the separation factors of the systems (hexane + benzene), (hexane + cyclohexane), and (benzene + cyclohexane). The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data.

  10. Fundamentals of liquid crystal devices

    CERN Document Server

    Yang, Deng-Ke

    2014-01-01

    Revised throughout to cover the latest developments in the fast moving area of display technology, this 2nd edition of Fundamentals of Liquid Crystal Devices, will continue to be a valuable resource for those wishing to understand the operation of liquid crystal displays. Significant updates include new material on display components, 3D LCDs and blue-phase displays which is one of the most promising new technologies within the field of displays and it is expected that this new LC-technology will reduce the response time and the number of optical components of LC-modules. Prof. Yang is a pion

  11. Bicontinuous liquid crystals

    CERN Document Server

    Lynch, Mathew L

    2005-01-01

    PrefaceIntroduction AcknowledgmentsBicontinuous Cubic Liquid Crystalline Materials: A Historical Perspective and Modern Assessment; Kr̄e LarssonIntermediate Phases; Michael C. Holmes and Marc S. LeaverCubic Phases and Human Skin: Theory and Practice; Steven Hoath and Lars NorlňThe Relationship between Bicontinuous Inverted Cubic Phases and Membrane Fusion; D.P. SiegelAspects of the Differential Geometry and Topology of Bicontinuous Liquid-Crystalline Phases; Robert W. CorkeryNovel L3 Phases and Their Macroscopic Properties; R. Beck and H. HoffmannBicontinuous Cubic Phases of Lipids with Entra

  12. Thermotropic liquid crystals recent advances

    CERN Document Server

    Ramamoorthy, Ayyalusamy

    2007-01-01

    This book covers developments in the field of thermotropic liquid crystals and their functional importance. It also presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these areas. New physical techniques that are powerful in characterizing these materials are discussed.

  13. Statistical theory of solid and liquid crystals

    Science.gov (United States)

    Bazarov, I. P.; Gevorkian, E. V.

    The statistical theory of solid and liquid crystals is presented with allowance for many-particle interactions. Statistical variational principles and various representations of Bogoliubov's equations are examined, and the thermodynamic properties of anharmonic solid crystals and microscopic models of liquid crystals are then discussed. Attention is given to the application of the theory developed here to the description of phase transitions in solid and liquid crystals. The stability of the far-range orientational and translational orders in solid and liquid crystals is discussed using a continuum model of liquid crystals and rigorous methods of statistical mechanics based on Bogoliubov's inequality.

  14. Cohesion energy calculations for ternary ionic novel crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez P, G.; Cabrera, E. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, 01000 Mexico D.F. (Mexico); Mijangos, R.R. [Centro de Investigacion en Fisica, Universidad de Sonora, A.P. 5-88, 83190 Hermosillo, Sonora (Mexico); Valdez, E. [Escuela Nacional de Estudios Profesionales Acatlan, Universidad Nacional Autonoma de Mexico, Santa Cruz Acatlan, Naucalpan (Mexico); Duarte, C. [Departamento de Geologia, Universidad de Sonora, 83000 Hermosillo, Sonora (Mexico)

    2001-07-01

    The present work calculates the value of the link energy of a crystalline ternary structure newly formed by alkali halides. The ternary structure prepared with different concentrations of KCl{sub x}KBrRbCl{sub 2} maintains a very good miscibility and stability. The calculation is based on the use of a generalization of the Vegard law (which generally is valid for binary compounds) for calculating the values of the lattice constant and the repulsive m exponent. The value of the lattice parameter given by X-ray diffractometry agrees with the close approximation of the calculated value of the method used. It also compares the value of energy cohesion obtained by the Born expression with more complex approximations. (Author)

  15. APPLICATION OF THE UNIFAC MODEL TO LIQUID-LIQUID EQUILIBRIA OF WATER-PROPIONIC ACID-SOLVENT TERNARIES*

    Directory of Open Access Journals (Sweden)

    Süheyla ÇEHRELİ

    2003-01-01

    Full Text Available The liquid-liquid equilibria of Water-Propionic Acid-Benzyl Alcohol, Water-Propionic Acid-Benzyl Acetate and Water-Propionic Acid-Dibenzyl Ether ternary systems were predicted by means of UNIFAC Model. For this purpose, multivariable Newton-Raphson convergence procedure was used. Experimental and model results were compared.

  16. Nanoassembly of Polydisperse Photonic Crystals based on Binary and Ternary Polymer Opal Alloys

    CERN Document Server

    Zhao, Qibin; Schafer, Christian; Spahn, Peter; Gallei, Markus; Herrmann, Lars; Petukhov, Andrei; Baumberg, Jeremy J

    2016-01-01

    Ordered binary and ternary photonic crystals, composed of different sized polymer-composite spheres with diameter ratios up to 120%, are generated using bending induced oscillatory shearing (BIOS). This viscoelastic system creates polydisperse equilibrium structures, producing mixed opaline colored films with greatly reduced requirements for particle monodispersity, and very different sphere size ratios, compared to other methods of nano-assembly.

  17. Liquid-liquid equilibria of the ternary system thiophene + octane + dimethyl sulfoxide at several temperatures.

    Science.gov (United States)

    Zhang, Wenlin; Hou, Kaihu; Mi, Guanjie; Chen, Na

    2010-01-01

    Liquid-liquid equilibria (LLE) data of the ternary system thiophene + octane + dimethyl sulfoxide at 40 degrees C, 50 degrees C, and 60 degrees C under atmospheric pressure were determined using an equilibrium cell with the standard curve method. The distribution of thiophene between extract and raffinate was measured and a practical formula of equilibria data for industrial extraction was proposed. NRTL model and UNIQUAC model were used to correlate and calculate LLE data of the system, and model parameters were determined using the simplex optimization method and imitative Newton method with a minimized objective function of mole fraction deviation. The rule of thermodynamic equilibria was used to deal with multi-roots problem in correlating process. Agreement between predicted and experimental data was satisfactory. The average absolute deviations of the NRTL and UNIQUAC models of thiophene mass fraction were 0.0040 and 0.0078, respectively. Both NRTL and UNIQUAC models were suitable for the calculation of LLE data of the ternary system thiophene + octane + dimethyl sulfoxide. The correlation accuracy of NRTL model is inferior to that of UNIQUAC model.

  18. Novel types of ionic thermotropic liquid crystals

    Science.gov (United States)

    Bruce, Duncan W.; Dunmur, David A.; Lalinde, Elena; Maitlis, Peter M.; Styring, Peter

    1986-10-01

    Liquid crystals are usually categorized as either lyotropic mesophases in which fluid anisotropy results from polar headgroup packing of amphiphilic molecules, or as thermotropic mesophases where the orientational order arises from interactions between partially rigid anisotropic molecules. The phase types exhibited by lyotropic and thermotropic liquid crystals have distinctive structures, optical textures and physical properties. Inclusion of a rigid anisotropic moiety into a lyotropic liquid crystal gives an additional source of orientational ordering, and can lead to phase behaviour encompassing both thermotropic and lyotropic liquid crystals. We have prepared a series of silver-containing thermotropic liquid crystals based on the bis(stilbazole) silver (I) cation. Some members of this series, in association with the amphiphilic counter-ion lauryl sulphate, form liquid crystal mesophases characteristic of both lyotropic and thermotropic liquid crystals.

  19. Understanding the vapor-liquid-solid growth and composition of ternary III-V nanowires and nanowire heterostructures

    Science.gov (United States)

    Dubrovskii, V. G.

    2017-11-01

    Based on the recent achievements in vapor-liquid-solid (VLS) synthesis, characterization and modeling of ternary III-V nanowires and axial heterostructures within such nanowires, we try to understand the major trends in their compositional evolution from a general theoretical perspective. Clearly, the VLS growth of ternary materials is much more complex than in standard vapor-solid epitaxy techniques, and even maintaining the necessary control over the composition of steady-state ternary nanowires is far from straightforward. On the other hand, VLS nanowires offer otherwise unattainable material combinations without introducing structural defects and hence are very promising for next-generation optoelectronic devices, in particular those integrated with a silicon electronic platform. In this review, we consider two main problems. First, we show how and by means of which parameters the steady-state composition of Au-catalyzed or self-catalyzed ternary III-V nanowires can be tuned to a desired value and why it is generally different from the vapor composition. Second, we present some experimental data and modeling results for the interfacial abruptness across axial nanowire heterostructures, both in Au-catalyzed and self-catalyzed VLS growth methods. Refined modeling allows us to formulate some general growth recipes for suppressing the unwanted reservoir effect in the droplet and sharpening the nanowire heterojunctions. We consider and refine two approaches developed to date, namely the regular crystallization model for a liquid alloy with a critical size of only one III-V pair at high supersaturations or classical binary nucleation theory with a macroscopic critical nucleus at modest supersaturations.

  20. Single-Crystal Growth of the Ternary BaFe2As2 Phase Using the Vertical Bridgman Technique

    Science.gov (United States)

    Morinaga, Rei; Matan, Kittiwit; Suzuki, Hiroyuki S.; Sato, Taku J.

    2009-01-01

    Ternary Ba-Fe-As system has been studied to determine a primary solidification field of the BaFe2As2 phase. We found that the BaFe2As2 phase most likely melts congruently and primarily solidifies either in the FeAs excess or BaxAs100-x excess liquid. Knowing the primary solidification field, we have performed the vertical Bridgman growth using the starting liquid composition of Ba15Fe42.5As42.5. Large single crystals of the typical size 10×4×2 mm3 were obtained and their quality was confirmed by X-ray Laue and neutron diffraction.

  1. Liquid crystals in biotribology synovial joint treatment

    CERN Document Server

    Ermakov, Sergey; Eismont, Oleg; Nikolaev, Vladimir

    2016-01-01

    This book summarizes the theoretical and experimental studies confirming the concept of the liquid-crystalline nature of boundary lubrication in synovial joints. It is shown that cholesteric liquid crystals in the synovial liquid play a significant role in the mechanism of intra-articular friction reduction. The results of structural, rheological and tribological research of the creation of artificial synovial liquids - containing cholesteric liquid crystals in natural synovial liquids - are described. These liquid crystals reproduce the lubrication properties of natural synovia and provide a high chondroprotective efficiency. They were tested in osteoarthritis models and in clinical practice.

  2. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    Science.gov (United States)

    Wang, W. L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-11-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate.

  3. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    Science.gov (United States)

    Wang, W .L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-01-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate. PMID:26552711

  4. Cohesion energy calculations for ternary ionic novel crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez Polo, G; Valdes, E. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Mijngos, R. R; Duarte, D. [Universidad de Sonora, Hermosillo, Sonora (Mexico)

    2001-12-01

    The present work calculates the value of the link energy of a crystalline ternary structure newly formed by alkali halides. The ternary structure prepared with different concentrations of KCI{sub x}KBr{sub y}RbCl{sub z} maintains a very good miscibility and stability. The calculation is based on the use of a generalization of the Vegard's law (which generally is valid for binary compounds) for calculating the values of the lattice constant and the repulsive m exponent. The values of the lattice parameter given X-ray diffractometry agrees with the close approximation of the calculated value of the method used. It also compares the value of energy cohesion obtained by the Born expression with more complex approximations. [Spanish] En el presente trabajo se calcula el valor de la energia de amarre de una estructura ternaria cristalina nueva formada por halogenuros alcalinos. La estructura ternaria preparada con diferentes concentraciones KCI{sub x}KBr{sub y}RbCl{sub z} mantiene una muy buena estabilidad y miscibilidad. El calculo se basa en el uso de una generalizacion de la ley de Vegard (que en general es valida para compuestos binarios) para calcular los valores de la constante de red y de exponente repulsivo m. El valor del parametro de red medido por difractometria de rayos X, concuerda en buena aproximacion con el valor calculado por el metodo usado. Tambien se compara el valor de la energia de cohesion obtenido por la expresion de Born con aproximaciones mas complejas.

  5. Liquid crystal infiltration of complex dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Gottardo, Stefano; Wiersma, Diederik S.; Vos, W.L

    2003-10-01

    Liquid crystal infiltration is becoming an important tool to control the optical properties of complex dielectric systems like photonic crystals and disordered dielectrics. We discuss the technical aspects of liquid crystal infiltration in meso-porous structures, give some details of the sample preparation process, and discuss possibilities for tuning the optical properties of both ordered and disordered systems.

  6. Thermoluminescence response of a mixed ternary alkali halide crystals exposed to gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez M, R.; Perez S, R. [Universidad de Sonora, Departamento de Investigacion en Fisica, Apdo. Postal 5-088, 83190 Hermosillo, Sonora (Mexico); Vazquez P, G.; Riveros, H. [UNAM, Instituto de Fisica, Apdo. Postal 20-364, 01000 Mexico D. F. (Mexico); Gonzalez M, P., E-mail: mijangos@cifus.uson.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-08-15

    Ionic crystals, mainly alkali halide crystals have been the subject of intense research for a better understanding of the luminescence properties of defects induced by ionizing radiation. The defects in crystals can be produced in appreciable concentration due to elastic stresses, radiation, and addition of impurities. These defects exhibit remarkable thermoluminescence properties. This work is concerned with the Tl properties of a ternary alkali halide crystal after being irradiated with gamma and beta rays. It has been found that the Tl glow peak of the crystal follows a rule of average associated to the Tl Temperatures of the components of the mixture, similarly to the response of europium doped binary mixed crystals KCl{sub x}KBr{sub 1-x} and KBr{sub x}RbBr{sub 1-x}. (Author)

  7. Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

    Science.gov (United States)

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

    Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

  8. Liquid-liquid phase equilibria for ternary systems of several polyethers with NaCl and H2O

    NARCIS (Netherlands)

    Milosevic, M.; Staal, K.J.J.; Schuur, Boelo; de Haan, A.B.

    2014-01-01

    Liquid–liquid extraction using polymers followed by induced phase separation is a potential energy reducing technology for water–salt separation. Ternary equilibrium data have been determined and reported for the (block co)poly ethers–sodium chloride–water systems at two different temperatures at

  9. Nanoscopic Manipulation and Imaging of Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Rosenblatt, Charles S. [Case Western Reserve Univ., Cleveland, OH (United States)

    2014-02-04

    This is the final project report. The project’s goals centered on nanoscopic imaging and control of liquid crystals and surfaces. We developed and refined techniques to control liquid crystal orientation at surfaces with resolution as small as 25 nm, we developed an optical imaging technique that we call Optical Nanotomography that allows us to obtain images inside liquid crystal films with resolution of 60 x 60 x 1 nm, and we opened new thrust areas related to chirality and to liquid crystal/colloid composites.

  10. Biased liquid crystal infiltrated photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Scolari, Lara

    2009-01-01

    partial differential equations. From the liquid crystal alignment the full tensorial dielectric permittivity in the capillaries is derived. The transmission spectrum for the photonic crystal fiber is obtained by solving the generalized eigenvalue problem deriving from Maxwell’s equations using a vector......A simulation scheme for the transmission spectrum of a photonic crystal fiber infiltrated with a nematic liquid crystal and subject to an external bias is presented. The alignment of the biased liquid crystal is simulated using the finite element method to solve the relevant system of coupled...

  11. Amplification of chirality in liquid crystals

    NARCIS (Netherlands)

    Eelkema, Rienk; Feringa, Ben L.

    2006-01-01

    The amplification of molecular chirality by liquid crystalline systems is widely applied in investigations towards enantioselective solvent - solute interactions, chiral supramolecular assemblies, smart materials, and the development of liquid crystal displays. Here we present an overview of recent

  12. Experimental and predicted refractive index properties in ternary mixtures of associated liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sechenyh, Vitaliy V.; Legros, Jean-Claude [MRC - Microgravity Research Centre, Universite Libre de Bruxelles (ULB), CP165/62, Avenue F.D. Roosevelt 50, B-1050 Brussels (Belgium); Shevtsova, Valentina, E-mail: vshev@ulb.ac.be [MRC - Microgravity Research Centre, Universite Libre de Bruxelles (ULB), CP165/62, Avenue F.D. Roosevelt 50, B-1050 Brussels (Belgium)

    2011-11-15

    Highlights: > Measurements of refractive indices of 200 different aqueous ternary mixtures have been performed for two wave lengths. > Refractive indices of the associated ternary mixtures can be modeled with a relative error of about 0.9. > Difference between experimental and calculated derivatives of refractive index with concentration is unsatisfactory large. - Abstract: Refractive indices of ternary mixtures formed by (water + ethanol + k-ethylene glycol) (when k is mono, di or tri) and (water + t-butanol + dimethyl sulfoxide) are presented over a wide range of mixture compositions. All measurements have been conducted at 298.15 K and atmospheric pressure using two light sources: one in the visible ({lambda} = 670 nm) and the other in the infrared ({lambda} = 925 nm) spectrum. The performance of several mixing rules that are commonly used in modeling optical constants are examined. We demonstrate that the refractive indices of the associated ternary mixtures can be modeled with a relative error of about 0.9% by using the thermodynamical properties of the pure components. The concentration derivatives of the refractive index are an important parameter, as they are required for different experimental techniques. These derivatives have been determined from the experimental data on refractive indices. However, applying mixing rules for calculation of the derivatives of the refractive indices with respect to concentrations does not provide satisfactory results in the case of ternary mixtures of associated liquids.

  13. Ternary liquid-liquid equilibria for mixtures of toluene + n-heptane + an ionic liquid

    NARCIS (Netherlands)

    Meindersma, G.W.; Podt, J.G.; de Haan, A.B.

    2006-01-01

    This research has been focused on a study of sulfolane and four ionic liquids as solvents in liquid–liquid extraction. Liquid–liquid equilibria data were obtained for mixtures of (sulfolane or 4-methyl-N-butylpyridinium tetrafluoroborate ([mebupy]BF4) or 1-ethyl-3-methylimidazolium ethylsulfate

  14. Liquid crystal tunable metamaterial absorber.

    Science.gov (United States)

    Shrekenhamer, David; Chen, Wen-Chen; Padilla, Willie J

    2013-04-26

    We present an experimental demonstration of electronically tunable metamaterial absorbers in the terahertz regime. By incorporation of active liquid crystal into strategic locations within the metamaterial unit cell, we are able to modify the absorption by 30% at 2.62 THz, as well as tune the resonant absorption over 4% in bandwidth. Numerical full-wave simulations match well to experiments and clarify the underlying mechanism, i.e., a simultaneous tuning of both the electric and magnetic response that allows for the preservation of the resonant absorption. These results show that fundamental light interactions of surfaces can be dynamically controlled by all-electronic means and provide a path forward for realization of novel applications.

  15. Characterising laser beams with liquid crystal displays

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2016-09-01

    Full Text Available decomposition of light has been known for a long time, applied mostly to pattern recognition, we illustrate how this technique can be implemented with the use of liquid-crystal displays. We show experimentally how liquid crystal displays can be used to infer...

  16. Liquid Crystals - The 'Fourth' Phase of Matter

    Indian Academy of Sciences (India)

    most well-known application is the liquid crystal-display (LCD), used in watches, calculators, flat panel displays used recently even in TV sets, and so on. The anisotropic properties of liquid crystals in refractive index and dielectric constant can be exploited for the purposes of creating flat-panel displays. Usually what is done ...

  17. Nanotube networks in liquid crystals

    Science.gov (United States)

    Urbanski, Martin; Lagerwall, Jan Peter F.; Scalia, Giusy

    2016-03-01

    Liquid crystals (LCs) are very attractive hosts for the organization of anisotropic nanoparticles such as carbon nanotubes (CNTs) because of the macroscopic organization resulting in properties of nanoparticles manifest at a macroscopic scale. Different types of LCs have demonstrated the ability to organize nanotubes, showing the generality of the approach, i.e., that the liquid crystallinity per se is the driving factor for the organization. Compared to standard nanotube composites (e.g. with disordered polymer hosts) the introduction of carbon nanotubes into an LC allows not only the transfer of the outstanding CNT properties to the macroscopic phase, providing strength and conductivity, but these properties also become anisotropic, following the transfer of the orientational order from the LC to the CNTs. The LC molecular structure plays an important even if ancillary role since it enters in the surface interactions, fulfilling a mediating action between the particle and the bulk of the LC. Isolated nanotubes can be obtained by optimized dispersions at lower concentrations and this process requires the use or development of tailored strategies like using solvents or even another LC for pre-dispersing CNTs. Aggregates or networks can be observed in poor dispersions and at higher nanoparticle concentrations. In those, due to surface interactions, the LC behaviour can be strongly affected with changes in phase sequences or transition temperatures and the effect is expected to be more pronounced as the concentration of nanotubes increases. We present preliminary investigations and observations on nanotube - LC systems based on a smectic LC host.

  18. Phototropic liquid crystals comprising one component

    Science.gov (United States)

    Sobolewska, Anna; Zawada, Joanna; Bartkiewicz, Stanislaw; Galewski, Zbigniew

    2013-09-01

    Phototropic liquid crystals (PtLC), in which the phase transition can be controlled by the light, are a new class of liquid crystal materials possessing number of potential applications, especially in photonic devices. So far a significant majority of PtLC materials has been realized by the doping a classical liquid crystal with a photochromic dye. Here we report PtLCs comprising a single compound. Liquid-crystalline and photochromic properties have been accomplished in alkylo-alkoxy derivatives of azobenzene. Such compounds show a rich polymorphism which can be controlled by the light. The phenomenon of the photochemical phase transition has been investigated by means of holographic grating recording.

  19. (Liquid + liquid) equilibria in ternary aqueous mixtures of phosphoric acid with organic solvents at T = 298.2 K

    Energy Technology Data Exchange (ETDEWEB)

    Ghanadzadeh, H., E-mail: hggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Department of Chemical Engineering, University of Guilan, Rasht (Iran, Islamic Republic of); Ghanadzadeh, A., E-mail: aggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Aghajani, Z.; Abbasnejad, S.; Shekarsaraee, S. [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of)

    2010-06-15

    (Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of left bracewater (1) + phosphoric acid (2) + organic solvents (3)right brace were determined at T = 298.2 K and atmospheric pressure. The organic solvents were cyclohexane, 2-methyl-2-butanol (tert-amyl alcohol), and isobutyl acetate. All the investigated systems exhibit Type-1 behaviour of LLE. The immiscibility region was found to be larger for the (water + phosphoric acid + cyclohexane) ternary system. The experimental LLE results were correlated with the NRTL model, and the binary interaction parameters were obtained. The reliability of the experimental tie-line results was tested through the Othmer-Tobias and Bachman correlation equations. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to these factors. The experimental results indicate the superiority of cyclohexane as the preferred solvent for the extraction of phosphoric acid from its aqueous solutions.

  20. The Crystal Growth and Characterization of CeT2Si2 Ternary Intermetallics (T = Ni, Pd, Pt)

    NARCIS (Netherlands)

    Menovsky, A.A.; Snel, C.E.; Gortenmulder, T.J.; Palstra, T.T.M.

    1986-01-01

    Bulk single crystals of the ternary intermetallic compounds CeNi2Si2, CePd2Si2 and CePt2Si2 have been grown from the melt with a modified “tri-arc” Czochralski method. The as-grown crystals were characterized by X-ray, microprobe, and chemical analyses. The measured densities were compared with the

  1. Stimuli-responsive photoluminescent liquid crystals.

    Science.gov (United States)

    Yamane, Shogo; Tanabe, Kana; Sagara, Yoshimitsu; Kato, Takashi

    2012-01-01

    We describe mechanochromic and thermochromic photoluminescent liquid crystals. In particular, mechanochromic photoluminescent liquid crystals found recently, which are new stimuli-responsive materials are reported. For example, photoluminescent liquid crystals having bulky dendritic moieties with long alkyl chains change their photoluminescent colors by mechanical stimuli associated with isothermal phase transitions. The photoluminescent properties of molecular assemblies depend on their assembled structures. Therefore, controlling the structures of molecular assemblies with external stimuli leads to the development of stimuli-responsive luminescent materials. Mechanochromic photoluminescent properties are also observed for a photoluminescent metallomesogen and a liquid-crystalline polymer. We also show thermochromic photoluminescent liquid crystals based on origo-(p-phenylenevinylene) and anthracene moieties and a thermochromic photoluminescent metallocomplex.

  2. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2017-10-01

    Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  3. Ternary liquid scintillator for optical-fiber applications

    Energy Technology Data Exchange (ETDEWEB)

    Franks, L.A.; Lutz, S.S.

    1981-06-01

    A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 5-amino-9-diethylaminobenz (a) phenoxazonium nitrate (Nile Blue Nitrate) as a solute in a fluor solvent such as benzyl alcohol. The use of PPD as an additional solute is also disclosed. The system is controllable by addition of a suitable quenching agent, such as phenol.

  4. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

    NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions

  5. Nanoparticles in discotic liquid crystals

    Science.gov (United States)

    Kumar, Sandeep

    The self-assembly of disc-shaped molecules creates discotic liquid crystals (DLCs). These nanomaterials of the sizes ranging from 2-6 nm are emerging as a new class of organic semiconducting materials. The unique geometry of columnar mesophases formed by discotic molecules is of great importance to study the one-dimensional charge and energy migration in organized systems. A number of applications of DLCs, such as, one-dimensional conductor, photoconductor, photovoltaic solar cells, light emitting diodes and gas sensors have been reported. The conductivity along the columns in columnar mesophases has been observed to be several orders of magnitude greater than in perpendicular direction and, therefore, DLCs are described as molecular wires. On the other hand, the fields of nanostructured materials, such as gold nanoparticles, quantum dots, carbon nanotubes and graphene, have received tremendous development in the past decade due to their technological and fundamental interest. Recently the hybridization of DLCs with various metallic and semiconducting nanoparticles has been realized to alter and improve their properties. These nanocomposites are not only of basic science interest but also lead to novel materials for many device applications. This article provides an overview on the development in the field of newly immersed discotic nanoscience. After a brief introduction of DLCs, the article will cover the inclusion of various zero-, one- and two-dimensional nanoparticles in DLCs. Finally, an outlook into the future of this newly emerging intriguing field of discotic nanoscience research will be provided.

  6. Octupolar tensors for liquid crystals

    Science.gov (United States)

    Chen, Yannan; Qi, Liqun; Virga, Epifanio G.

    2018-01-01

    A third-rank three-dimensional symmetric traceless tensor, called the octupolar tensor, has been introduced to study tetrahedratic nematic phases in liquid crystals. The octupolar potential, a scalar-valued function generated on the unit sphere by that tensor, should ideally have four maxima (on the vertices of a tetrahedron), but it was recently found to possess an equally generic variant with three maxima instead of four. It was also shown that the irreducible admissible region for the octupolar tensor in a three-dimensional parameter space is bounded by a dome-shaped surface, beneath which is a separatrix surface connecting the two generic octupolar states. The latter surface, which was obtained through numerical continuation, may be physically interpreted as marking a possible intra-octupolar transition. In this paper, by using the resultant theory of algebraic geometry and the E-characteristic polynomial of spectral theory of tensors, we give a closed-form, algebraic expression for both the dome-shaped surface and the separatrix surface. This turns the envisaged intra-octupolar transition into a quantitative, possibly observable prediction.

  7. Solid-liquid equilibria for a pyrrolidinium-based common-cation ternary ionic liquid system, and for a pyridinium-based ternary reciprocal ionic liquid system: an experimental study and a thermodynamic model.

    Science.gov (United States)

    Mirarabrazi, Meysam; Stolarska, Olga; Smiglak, Marcin; Robelin, Christian

    2017-12-20

    The present paper describes an experimental study and a thermodynamic model for the phase diagrams of the common-cation ternary system [C 4 MPyrr]Cl-[C 4 MPyrr]Br-[C 4 MPyrr]BF 4 (where [C 4 MPyrr] refers to 1-butyl-1-methyl-pyrrolidinium) and of the ternary reciprocal system [C 2 Py], [C 4 Py]‖Cl, Br (where [C n Py] refers to 1-alkyl-pyridinium). Phase equilibria were measured by Differential Scanning Calorimetry (DSC) for two isoplethal sections in the common-cation pyrrolidinium-based ternary system. Phase diagram measurements were recently performed for the four common-ion binary subsystems and the two diagonal sections in the pyridinium-based ternary reciprocal system. In each case, the Modified Quasichemical Model was used to model the liquid solution, and the Compound Energy Formalism was used for the relevant solid solutions. For the ternary reciprocal system, the missing thermodynamic properties of the pure compounds were assessed using the Volume-based Thermodynamics (VBT) from Glasser and Jenkins, making it possible to estimate the exchange Gibbs free energy for the reaction [C 2 Py]Br (liquid) + [C 4 Py]Cl (liquid) = [C 2 Py]Cl (liquid) + [C 4 Py]Br (liquid). The experimental diagonal sections [C 4 Py]Br-[C 2 Py]Cl and [C 4 Py]Cl-[C 2 Py]Br were satisfactorily reproduced using solely the optimized model parameters for the four common-ion binary subsystems.

  8. Formation mechanism of the low-frequency locally resonant band gap in the two-dimensional ternary phononic crystals

    Science.gov (United States)

    Wang, Gang; Liu, Yao-Zong; Wen, Ji-Hong; Yu, Dian-Long

    2006-02-01

    The low-frequency band gap and the corresponding vibration modes in two-dimensional ternary locally resonant phononic crystals are restudied successfully with the lumped-mass method. Compared with the work of C. Goffaux and J. Sánchez-Dehesa (Phys. Rev. B 67 14 4301(2003)), it is shown that there exists an error of about 50% in their calculated results of the band structure and one band is missing in their results. Moreover, the in-plane modes shown in their paper are improper, which results in the wrong conclusion on the mechanism of the ternary locally resonant phononic crystals. Based on the lumped-mass method and better description of the vibration modes according to the band gaps, the locally resonant mechanism in forming the subfrequency gaps is thoroughly analysed. The rule used to judge whether a resonant mode in the phononic crystals can result in a corresponding subfrequency gap is also verified in this ternary case.

  9. Photonics and lasing in liquid crystal materials

    National Research Council Canada - National Science Library

    Peter Palffy-Muhoray; Wenyi Cao; Michele Moreira; Bahman Taheri; Antonio Munoz

    2006-01-01

    Owing to fundamental reasons of symmetry, liquid crystals are soft materials. This softness allows long length-scales, large susceptibilities and the existence of modulated phases, which respond readily to external fields...

  10. Liquid crystal on subwavelength metal gratings

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P.; Barnik, M. I.; Artemov, V. V.; Shtykov, N. M.; Geivandov, A. R.; Yudin, S. G.; Gorkunov, M. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences, Leninsky pr. 59, 119333 Moscow (Russian Federation)

    2015-06-14

    Optical and electrooptical properties of a system consisting of subwavelength metal gratings and nematic liquid crystal layer are studied. Aluminium gratings that also act as interdigitated electrodes are produced by focused ion beam lithography. It is found that a liquid crystal layer strongly influences both the resonance and light polarization properties characteristic of the gratings. Enhanced transmittance is observed not only for the TM-polarized light in the near infrared spectral range but also for the TE-polarized light in the visible range. Although the electrodes are separated by nanosized slits, and the electric field is strongly localized near the surface, a pronounced electrooptical effect is registered. The effect is explained in terms of local reorientation of liquid crystal molecules at the grating surface and propagation of the orientational deformation from the surface into the bulk of the liquid crystal layer.

  11. Structure and Properties of Liquid Crystals

    CERN Document Server

    Blinov, Lev M

    2011-01-01

    This book by Lev M. Blinov is ideal to guide researchers from their very first encounter with liquid crystals to the level where they can perform independent experiments on liquid crystals with a thorough understanding of their behaviour also in relation to the theoretical framework. Liquid crystals can be found everywhere around us. They are used in virtually every display device, whether it is for domestic appliances of for specialized technological instruments. Their finely tunable optical properties make them suitable also for thermo-sensing and laser technologies. There are many monographs written by prominent scholars on the subject of liquid crystals. The majority of them presents the subject in great depth, sometimes focusing on a particular research aspect, and in general they require a significant level of prior knowledge. In contrast, this books aims at an audience of advanced undergraduate and graduate students in physics, chemistry and materials science. The book consists of three parts: the firs...

  12. Liquid crystal interfaces: Experiments, simulations and biosensors

    Science.gov (United States)

    Popov, Piotr

    Interfacial phenomena are ubiquitous and extremely important in various aspects of biological and industrial processes. For example, many liquid crystal applications start by alignment with a surface. The underlying mechanisms of the molecular organization of liquid crystals at an interface are still under intensive study and continue to be important to the display industry in order to develop better and/or new display technology. My dissertation research has been devoted to studying how complex liquid crystals can be guided to organize at an interface, and to using my findings to develop practical applications. Specifically, I have been working on developing biosensors using liquid-crystal/surfactant/lipid/protein interactions as well as the alignment of low-symmetry liquid crystals for potential new display and optomechanical applications. The biotechnology industry needs better ways of sensing biomaterials and identifying various nanoscale events at biological interfaces and in aqueous solutions. Sensors in which the recognition material is a liquid crystal naturally connects the existing knowledge and experience of the display and biotechnology industries together with surface and soft matter sciences. This dissertation thus mainly focuses on the delicate phenomena that happen at liquid interfaces. In the introduction, I start by defining the interface and discuss its structure and the relevant interfacial forces. I then introduce the general characteristics of biosensors and, in particular, describe the design of biosensors that employ liquid crystal/aqueous solution interfaces. I further describe the basic properties of liquid crystal materials that are relevant for liquid crystal-based biosensing applications. In CHAPTER 2, I describe the simulation methods and experimental techniques used in this dissertation. In CHAPTER 3 and CHAPTER 4, I present my computer simulation work. CHAPTER 3 presents insight of how liquid crystal molecules are aligned by

  13. (Liquid + liquid) equilibria for ternary mixtures of (alkane + benzene + [EMpy] [ESO{sub 4}]) at several temperatures and atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Emilio J.; Calvar, Noelia; Gonzalez, Begona [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain); Dominguez, Angeles [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain)], E-mail: admguez@uvigo.es

    2009-11-15

    In this work, the separation of benzene from aliphatic hydrocarbons (hexane, or heptane) is investigated by extraction with 1-ethyl-3-methylpyridinium ethylsulphate ionic liquid, [EMpy][ESO{sub 4}]. (Liquid + liquid) equilibria (LLE) data are determined for the ternary systems: {l_brace}hexane (1) + benzene (2) + [EMpy][ESO{sub 4}] (3){r_brace} at T = (283.15, 293.15, 298.15, and 303.15) K and {l_brace}heptane (1) + benzene (2) + [EMpy][ESO{sub 4}] (3){r_brace} at T = (283.15 and 298.15) K and atmospheric pressure. The selectivity and distribution coefficient, derived from the tie line data, were used to determine whether the ionic liquid is a good solvent for the extraction of aromatic from aliphatic compounds. The consistency of the tie line data was ascertained by applying the Othmer-Tobias and Hand equations. The experimental results for the ternary systems were well correlated with the NRTL equation. A study of the temperature effect and the influence of the chain length of the alkanes were realized. The results obtained were compared with other ionic liquids. There are no literature data for the mixtures discussed in this paper.

  14. Polymer-dispersed liquid crystal elastomers

    OpenAIRE

    Resetic, A; Milavec, J; B Zupancic; Domenici, V; Zalar, B.

    2016-01-01

    The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. Here we report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty. Their thermal shape memory anisotropy is imprinted by curing in external magnetic field, providing for conventional moulding of macroscopically siz...

  15. Vacuum pyrolysis characteristics and kinetic analysis of liquid crystal from scrap liquid crystal display panels.

    Science.gov (United States)

    Chen, Ya; Zhang, Lingen; Xu, Zhenming

    2017-04-05

    Recycling of waste liquid crystal display (LCD) panels is an urgent task with the rapid expanding LCD market. However, as important composition of LCD panels, the treatment of liquid crystal is seldom concerned for its low concentration. In present study, a stripping product enriched liquid crystal and indium is gained by mechanical stripping process, in which liquid crystal is enriched from 0.3wt.% to 53wt.% and indium is enriched from 0.02wt.% to 7.95wt.%. For the stripping product, liquid crystal should be removed before indium recovery because (a) liquid crystal will hinder indium recycling; (b) liquid crystal is hazardous waste. Hence, an effective and green approach by vacuum pyrolysis is proposed to treat liquid crystal in the stripping product. The results are summarized as: (i) From the perspective of apparent activation energy, the advantages of vacuum pyrolysis is expounded according to kinetic analysis. (ii) 89.10wt.% of liquid crystal is converted and the content of indium in residue reaches 14.18wt.% under 773K, 15min and system pressure of 20Pa. This study provides reliable information for further industrial application and an essential pretreatment for the next step of indium recycling. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Analysis of cutoff frequency in one dimensional ternary superconducting photonic crystal

    Science.gov (United States)

    K. P., Sreejith; Maria D'souza, Nirmala; Mathew, Vincent

    2017-09-01

    By means of two fluid model and transfer matrix method, we have theoretically investigated the transmittance property of a one dimensional ternary photonic crystal consist of a pair of superconducting materials and a dielectric in the infrared frequency region. We mainly focus on the analysis of cutoff frequency since the calculations can be useful in the fabrication of optical devices such as reflector, high pass filter etc. The study reveals that the cutoff frequency is sensitive to thickness of superconducting materials, dielectric layer thickness, operating temperature and refractive index of intermediate dielectric. Cutoff frequency shifted to higher frequency region on increasing number of periods and superconductor layer thickness where as it reduces on increasing dielectric thickness, operating temperature and refractive index of intermediate dielectric. Furthermore, we compared the cutoff frequency of three different 1D ternary photonic crystals comprising of a dielectric and a pair of high-high, high-low and low-low temperature superconducting materials. Our comparison results shows that the cutoff frequency can be effectively modified with different combination of superconducting materials.

  17. Liquid crystals of carbon nanotubes and graphene.

    Science.gov (United States)

    Zakri, Cécile; Blanc, Christophe; Grelet, Eric; Zamora-Ledezma, Camilo; Puech, Nicolas; Anglaret, Eric; Poulin, Philippe

    2013-04-13

    Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic liquid crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene liquid crystals are reported. The possibility to obtain water-based liquid crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as liquid crystals and provides new methodologies for the still challenging characterization of such materials.

  18. Molecular Models of Liquid Crystal Elastomers

    Science.gov (United States)

    Rajshekhar

    Liquid crystal elastomers combine the elastic properties of conventional rubbers with the optical properties of liquid crystals. This dual nature gives rise to unusual physical properties, including the stress induced transition from a polydomain state, consisting of multiple nematic regions with independent orientations, to a monodomain state consisting of a single nematic region with a uniform director. We propose several molecular-scale coarse-grained models of liquid crystal elastomers with varying degrees of resolution. The models employ the Gay-Berne soft potential, and exhibit the chain connectivity of a diamond network. Simulation results show that these models are able to capture the polydomain state exhibited by liquid crystal elastomers in the absence of any external stress. When subjected to uniaxial stress, our models exhibit a polydomain to monodomain transition. We explain that the polydomain state occurs through the aggregation of liquid crystal molecules assisted by crosslinking sites, and conclude that the transition mechanism to the monodomain state is based on the reorientation of nematic domains along the direction of applied stress. Our modeling efforts are primarily focused on three models. The first two models consider the effects of rigid and flexible crosslinkers in liquid crystal elastomers with a diamond topology for chain connectivity. The third model deviates from the diamond network topology and adopts a random network topology.

  19. Viscoelastic modes in chiral liquid crystals

    Indian Academy of Sciences (India)

    amit@fs.rri.local.net (Amit Kumar Agarwal)

    our studies on the viscoelastic modes of some chiral liquid crystals using dynamic light scattering. We discuss viscoelastic modes corresponding to the C director fluctuations in the chiral smectic C phase and the behaviour of the Goldstone-mode near the chiral smectic C–smectic A phase transition. In cholesteric liquid ...

  20. Passive Sensor Materials Based on Liquid Crystals

    Science.gov (United States)

    2011-03-12

    Seminar, Chemical Engineering,,Virginia Tech, October, 2008. Abbott, N.L. “Biomolecular Analysis based on Liquid Crystals”, Innovative Molecular Analysis ...of Liquid Crystals" Columbia University, February, 2010, "Novel Colloidal and Interfacial Phenomena in Liquid Crystalline Systems" CBD Conference...extended to other oils (silicone oil and paraffin oil droplets) and the size of capsule templates was also varied (0.7 to 10 μm, Figure 15) to

  1. Electro-osmosis in nematic liquid crystals

    Science.gov (United States)

    Tovkach, O. M.; Calderer, M. Carme; Golovaty, Dmitry; Lavrentovich, Oleg; Walkington, Noel J.

    2016-07-01

    We derive a mathematical model of a nematic electrolyte based on a variational formulation of nematodynamics. We verify the model by comparing its predictions to the results of the experiments on the substrate-controlled liquid-crystal-enabled electrokinetics. In the experiments, a nematic liquid crystal confined to a thin planar cell with surface-patterned anchoring conditions exhibits electro-osmotic flows along the "guiding rails" imposed by the spatially varying director. Extending our previous work, we consider a general setup which incorporates dielectric anisotropy of the liquid-crystalline matrix and the full set of nematic viscosities.

  2. Key Developments in Ionic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Alexandra Alvarez Fernandez

    2016-05-01

    Full Text Available Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

  3. Crystal structure of the ternary silicide Gd2Re3Si5

    Directory of Open Access Journals (Sweden)

    Vitaliia Fedyna

    2014-12-01

    Full Text Available A single crystal of the title compound, the ternary silicide digadolinium trirhenium pentasilicide, Gd2Re3Si5, was isolated from an alloy of nominal composition Gd20Re30Si50 synthesized by arc melting and investigated by X-ray single-crystal diffraction. Its crystal structure belongs to the U2Mn3Si5 structure type. All atoms in the asymmetric lie on special positions. The Gd site has site symmetry m..; the two Mn atoms have site symmetries m.. and 2.22; the three Si atoms have site symmetries m.., ..2 and 4.. . The coordination polyhedra of the Gd atoms have 21 vertices, while those of the Re atoms are cubooctahedra and 13-vertex polyhedra. The Si atoms are arranged as tricapped trigonal prisms, bicapped square antiprisms, or 11-vertex polyhedra. The crystal structure of the title compound is also related to the structure types CaBe2Ge2 and W5Si3. It can be represented as a stacking of Gd-centred polyhedra of composition [GdSi9]. The Re atoms form infinite chains with an Re—Re distance of 2.78163 (5 Å and isolated squares with an Re—Re distance of 2.9683 (6 Å.

  4. Charge transfer reactions in nematic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.]|[Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry

    1998-07-01

    Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.

  5. separation of strontium and cesium from ternary and quaternary lithium chloride-potassium chloride salts via melt crystallization

    Directory of Open Access Journals (Sweden)

    Ammon N. Williams

    2015-12-01

    Full Text Available Separation of cesium chloride (CsCl and strontium chloride (SrCl2 from the lithium chloride-potassium chloride (LiCl-KCl salt was studied using a melt crystallization process similar to the reverse vertical Bridgeman growth technique. A ternary SrCl2-LiCl-KCl salt was explored at similar growth rates (1.8–5 mm/h and compared with CsCl ternary results to identify similarities. Quaternary experiments were also conducted and compared with the ternary cases to identify trends and possible limitations to the separations process. In the ternary case, as much as 68% of the total salt could be recycled per batch process. In the quaternary experiments, separation of Cs and Sr was nearly identical at the slower rates; however, as the growth rate increased, SrCl2 separated more easily than CsCl. The quaternary results show less separation and rate dependence than in both ternary cases. As an estimated result, only 51% of the total salt could be recycled per batch. Furthermore, two models have been explored to further understand the growth process and separation. A comparison of the experimental and modeling results reveals that the nonmixed model fits reasonably well with the ternary and quaternary data sets. A dimensional analysis was performed and a correlation was identified to semipredict the segregation coefficient.

  6. Crystal Structures of Murine Carnitine Acetyltransferase in Ternary Complexes with Its Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao,Y.; Jogl, G.; Tong, L.

    2006-01-01

    Carnitine acyltransferases catalyze the reversible exchange of acyl groups between coenzyme A (CoA) and carnitine. They have important roles in many cellular processes, especially the oxidation of long-chain fatty acids in the mitochondria for energy production, and are attractive targets for drug discovery against diabetes and obesity. To help define in molecular detail the catalytic mechanism of these enzymes, we report here the high resolution crystal structure of wild-type murine carnitine acetyltransferase (CrAT) in a ternary complex with its substrates acetyl-CoA and carnitine, and the structure of the S554A/M564G double mutant in a ternary complex with the substrates CoA and hexanoylcarnitine. Detailed analyses suggest that these structures may be good mimics for the Michaelis complexes for the forward and reverse reactions of the enzyme, representing the first time that such complexes of CrAT have been studied in molecular detail. The structural information provides significant new insights into the catalytic mechanism of CrAT and possibly carnitine acyltransferases in general.

  7. Polymer-dispersed liquid crystal elastomers

    Science.gov (United States)

    Rešetič, Andraž; Milavec, Jerneja; Zupančič, Blaž; Domenici, Valentina; Zalar, Boštjan

    2016-10-01

    The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. Here we report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty. Their thermal shape memory anisotropy is imprinted by curing in external magnetic field, providing for conventional moulding of macroscopically sized soft, thermomechanically active elastic objects of general shapes. The binary soft-soft composition of isotropic elastomer matrix, filled with freeze-fracture-fabricated, oriented liquid crystal elastomer microparticles as colloidal inclusions, allows for fine-tuning of thermal morphing behaviour. This is accomplished by adjusting the concentration, spatial distribution and orientation of microparticles or using blends of microparticles with different thermomechanical characteristics. We demonstrate that any Gaussian thermomechanical deformation mode (bend, cup, saddle, left and right twist) of a planar sample, as well as beat-like actuation, is attainable with bilayer microparticle configurations.

  8. Characterising laser beams with liquid crystal displays

    Science.gov (United States)

    Dudley, Angela; Naidoo, Darryl; Forbes, Andrew

    2016-02-01

    We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. Although the modal decomposition of light has been known for a long time, applied mostly to pattern recognition, we illustrate how this technique can be implemented with the use of liquid-crystal displays. We show experimentally how liquid crystal displays can be used to infer the intensity, phase, wavefront, Poynting vector, and orbital angular momentum density of unknown optical fields. This measurement technique makes use of a single spatial light modulator (liquid crystal display), a Fourier transforming lens and detector (CCD or photo-diode). Such a diagnostic tool is extremely relevant to the real-time analysis of solid-state and fibre laser systems as well as mode division multiplexing as an emerging technology in optical communication.

  9. Full color waveguide liquid crystal display.

    Science.gov (United States)

    Zhou, Xiaochen; Qin, Guangkui; Wang, Long; Chen, Zhuo; Xu, Xiaoguang; Dong, Youmei; Moheghi, Alireza; Yang, Deng-Ke

    2017-09-15

    We developed a waveguide liquid crystal display from a liquid crystal (LC)/polymer composite. It does not need polarizers or color filters. It is illuminated by color LEDs installed on its edge. The light produced by the edge LEDs is coupled into the display and then waveguided through the display. When the LC is in the transparent state, the incident light is waveguided through and no light comes out of the viewing side of the display. When the LC is in the scattering state, the incident light is scattered and comes out of the display. It can be used either for transparent display or for direct view display. The composite has a submillisecond response time, and a field sequential scheme can be used to display full color images. Because the display does not need polarizers or color filters, its energy efficiency is much higher than current liquid crystal displays.

  10. Microfluidic Flow of Cholesteric Liquid Crystals

    CERN Document Server

    Wiese, Oliver; Henrich, Oliver

    2016-01-01

    We explore the rheology and flow-induced morphological changes of cholesteric liquid crystal patterns subject to Poiseuille flow within a slab geometry, and under different anchoring conditions at the wall. Our focus is particularly on the behaviour of Cholesteric Fingers of the first kind and of Blue Phase II. Depending on the applied pressure gradient, we observe a number of dynamic regimes with different rheological properties. Our results provide the first insight into the flow response of cholesteric phases with fully two- or three-dimensional director field patterns and normal and planar degenerate anchoring conditions as commonly realised in experiments. They are also of high relevance for a fundamental understanding of complex liquid crystals in confinement and an important step towards future microfluidic applications that are based on cholesteric liquid crystals.

  11. Calculation of liquid-liquid phase separation in a ternary system of a polymer in a mixture of a solvent and a nonsolvent

    NARCIS (Netherlands)

    Altena, Frank W.; Smolders, C.A.

    1982-01-01

    A numerical method for the calculation of the binodal of liquid-liquid phase separation in a ternary system is described. The Flory-Huggins theory for three-component systems is used. Binodals are calculated for polymer/solvent/nonsolvent systems which are used in the preparation of asymmetric

  12. Liquid-liquid equilibria for the ternary systems sulfolane + octane + benzene, sulfolane + octane + toluene and sulfolane + octane + p-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Kim, H. [Seoul National Univ. (Korea, Republic of). Dept. of Chemical Engineering

    1995-03-01

    Sulfolane is widely used as a solvent for the extraction of aromatic hydrocarbons. Ternary phase equilibrium data are essential for the proper understanding of the solvent extraction process. Liquid-liquid equilibrium data for the systems sulfolane + octane + benzene, sulfolane + octane + toluene and sulfolane + octane + p-xylene were determined at 298.15, 308.15, and 318.15 K. Tie line data were satisfactorily correlated by the Othmer and Tobias method. The experimental data were compared with the values calculated by the UNIQUAC and NRTL models. Good quantitative agreement was obtained with these models. However, the calculated values based on the NRTL model were found to be better than those based on the UNIQUAC model.

  13. Liquid-liquid equilibrium measurement of ternary system containing β-caryophyllene in the water and 2-propanol mixture

    Science.gov (United States)

    Tetrisyanda, Rizky; Kuswandi, Wibawa, Gede

    2017-01-01

    To obtain a high purity of clove oil, it is needed to separate β-caryophyllene from the oil mixtures.The separation of this component could be obtained by solvent extraction. In this work, liquid-liquid equilibrium (LLE) data were measured for the ternary system of water β-caryophyllene (1) + 2-propanol (2) + water (3) at temperature 303.15 K, 313.15 K and 323.15K under atmospheric pressure. The experimental LLE data were correlated with the NRTL and UNIQUAC models. The reliability of these models is tested by comparison with experimental results. The varied temperatures studied in this work have significant influence to the two-phase area and the solubility of 2-propanol and β-caryophyllene in the aqueous phase.

  14. Solid-liquid equilibria in the ternary system NaBr-KBr-H2O at 398 K

    Science.gov (United States)

    Cui, Rui-Zhi; Zhang, Ting-Ting; Wang, Wei; Sang, Shi-Hua

    2017-09-01

    The solubilities of the ternary system NaBr-KBr-H2O were investigated by isothermal method at 398 K. On the basis of the experimental data, the phase diagram was plotted. In the phase diagram of ternary system NaBr-KBr-H2O at 398 K, no complex salt or solid solution was found. It belongs to simple co-saturation type. There are only one invariant point, two univariant curves, and two crystallization fields corresponding to NaBr and KBr. Using the equilibrium solubilities data of the ternary system at 398 K, mixing ioninteraction parameter ΨNa,K,Br of Pitzer's equation was fitted by multiple linear regression method. Based on the Pitzer model and its extended Harvie-Weare (HW) model, the solubilities of phase equilibrium in the ternary system NaBr-KBr-H2O at 398 K were calculated. The phase diagram of the ternary system was plotted. The results show that calculated values have a good agreement with measured experimental data. It can demonstrate the accuracy of the experimental data, and it also shows that reasonable parameters of the Pitzer model can be used in ternary system NaBr-KBr-H2O at 398 K.

  15. Infrared scintillation in gases, liquids and crystals

    NARCIS (Netherlands)

    Belogurov, S.; Bressi, G; Carugno, G.; Conti, E; Iannuzzi, D; Meneguzzo, AT

    2000-01-01

    We report about experimental evidences of infrared scintillation in gaseous, liquid and crystal samples. We firstly studied noble gases at room temperature and near atmospheric pressure in the wavelength range between 0.7 and 1.81 mum. Ar gas emits infrared photons when irradiated by a proton beam.

  16. Characteristics of bulk liquid undercooling and crystallization ...

    Indian Academy of Sciences (India)

    157–161. c Indian Academy of Sciences. Characteristics of bulk liquid undercooling and crystallization behaviors of jet electrodeposition Ni–W–P alloy. J K YU. ∗. , Y H WANG, G Z XING, Q QIAO, B LIU, Z J CHU, C L LI and F YOU. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University,.

  17. Characteristics of bulk liquid undercooling and crystallization ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 1. Characteristics of bulk liquid undercooling and crystallization behaviors of jet electrodeposition Ni–W–P alloy. J K Yu Y H Wang G Z Xing Q Qiao B Liu Z J Chu C L Li F You. Volume 38 Issue 1 February 2015 pp 157-161 ...

  18. Supramolecular liquid crystal displays : construction and applications

    NARCIS (Netherlands)

    Hoogboom, Joannes Theodorus Valentinus

    2004-01-01

    This thesis describes chemical methodologies, which can be ued to construct alignment layers for liquid crystal display purposes in a non-clean room environment, by making use of supramolecular chemistry. These techniques are subsequently used to attain control over LCD-properties, both pre- and

  19. Ultrabroadband terahertz spectroscopy of a liquid crystal

    DEFF Research Database (Denmark)

    Vieweg, N.; Fischer, B. M.; Reuter, M.

    2012-01-01

    Liquid crystals (LCs) are becoming increasingly important for applications in the terahertz frequency range. A detailed understanding of the spectroscopic parameters of these materials over a broad frequency range is crucial in order to design customized LC mixtures for improved performance. We p...

  20. Goethite liquid crystals and magnetic field effects

    NARCIS (Netherlands)

    van den Pol, E

    2010-01-01

    In this thesis the liquid crystal phase behavior of colloidal, boardlike, goethite (alpha-FeOOH) particles is described. Apart from the nematic phase, a smectic A phase is formed in systems with a low and high polydispersity. Strong fractionation occurs which is able to reduce the local length

  1. Electric heating effects in nematic liquid crystals

    Science.gov (United States)

    Yin, Y.; Shiyanovskii, S. V.; Lavrentovich, O. D.

    2006-07-01

    Electric heating effects in the nematic liquid crystal change the liquid crystal physical properties and dynamics. We propose a model to quantitatively describe the heating effects caused by dielectric dispersion and ionic conductivity in the nematic liquid crystals upon the application of an ac electric field. The temperature increase of the liquid crystal cell is related to the properties of the liquid crystal such as the imaginary part of the dielectric permittivity, thermal properties of the bounding plates, and the surrounding medium as well as frequency and amplitude of the electric field. To study the temperature dynamics experimentally, we use a small thermocouple inserted directly into the nematic bulk; we assure that the thermocouple does not alter the thermal behavior of the system by comparing the results to those obtained by a noncontact birefringent probing technique recently proposed by Wen and Wu [Appl. Phys. Lett. 86, 231104 (2005)]. We determine how the temperature dynamics and the stationary value of the temperature increase depend on the parameters of the materials and the applied field. We used different surrounding media, from extremely good heat conductors such as aluminum cooling device to extremely poor conductor, Styrofoam; these two provide two limiting cases as compared to typical conditions of nematic cell exploitation in a laboratory or in commercial devices. The experiments confirm the theoretical predictions, namely, that the temperature rise is controlled not only by the heat transfer coefficient of the surrounding medium (as in the previous model) but also by the thickness and the thermal conductivity coefficient of the bounding plates enclosing the nematic layer. The temperature increase strongly depends on the director orientation and can change nonmonotonously with the frequency of the applied field.

  2. ETHANOL, ACETIC ACID, AND WATER ADSORPTION FROM BINARY AND TERNARY LIQUID MIXTURES ON HIGH-SILICA ZEOLITES

    Science.gov (United States)

    Adsorption isotherms were measured for ethanol, acetic acid, and water adsorbed on high-silica ZSM-5 zeolite powder from binary and ternary liquid mixtures at room temperature. Ethanol and water adsorption on two high-silica ZSM-5 zeolites with different aluminum contents and a h...

  3. Ultrashort silica liquid crystal photonic crystal fiber polarization rotator.

    Science.gov (United States)

    Hameed, Mohamed Farhat O; Obayya, Salah S A

    2014-02-15

    In this Letter, an ultra-compact polarization rotator (PR) based on silica photonic crystal fiber with liquid crystal core is introduced and analyzed using full-vectorial finite difference approaches. The analyzed parameters of the suggested PR are the conversion length, modal hybridness, power conversion and crosstalk. In addition, the fabrication tolerance analysis of the reported design is investigated in detail. The proposed PR has an ultra-compact device length of 4.085 μm and an almost 100% polarization conversion ratio.

  4. Temperature Dependence of Light Transmittance in Polymer Dispersed Liquid Crystals

    OpenAIRE

    Bloisi, F.; Ruocchio, C.; Vicari, L

    1997-01-01

    Polymer Dispersed Liquid Crystals (PDLC) axe composite materials made of a dispersion of liquid crystal droplets in a polymeric matrix. When the liquid crystal is in the nematic phase, droplets appeax as optically anisotropic spheres and the material is opaque white. Sample transmittance is a function of the temperature. If the liquid crystal refractive index in the isotropic phase is equal to the one of the polymer, after the nematic-isotropic transition the material is transparent. We prese...

  5. Atomic mobility in a ternary liquid Ga-In-Sn alloy of the eutectic composition

    Science.gov (United States)

    Nefedov, D. Yu.; Antonenko, A. O.; Podorozhkin, D. Yu.; Uskov, A. V.; Charnaya, E. V.; Lee, M. K.; Chang, J. L.; Haase, J.; Michel, D.; Kumzerov, Yu. A.; Fokin, A. V.; Samoilovich, M. I.; Bugaev, A. S.

    2017-02-01

    The nuclear spin-lattice relaxation and Knight shift of 71Ga, 69Ga, and 115In nuclei in a ternary liquid gallium-indium-tin alloy of the eutectic composition, which was introduced into pores of an opal matrix and porous glasses with pore sizes of 18 and 7 nm, have been investigated and compared with those for the bulk melt. It has been found that longitudinal relaxation is accelerated and the Knight shift is decreased, depending on the size of pores. The correlation time of the atomic motion has been calculated for the nanostructured melt in porous matrices. It has been shown that the atomic mobility in the melt decreases with decreasing size of pores in the glasses.

  6. Ternary liquid-liquid equilibria for the phenolic compounds extraction from artificial textile industrial waste

    Science.gov (United States)

    Fardhyanti, Dewi Selvia; Prasetiawan, Haniif; Hermawan, Sari, Lelita Sakina

    2017-03-01

    Liquid waste in textile industry contains large amounts of dyes and chemicals which are capable of harming the environment and human health. It is due to liquid waste characteristics which have high BOD, COD, temperature, dissolved and suspended solid. One of chemical compound which might be harmful for environment when disposed in high concentration is phenol. Currently, Phenol compound in textile industrial waste has reached 10 ppm meanwhile maximum allowable phenol concentration is not more than 0.2 ppm. Otherwise, Phenol also has economic value as feedstock of plastic, pharmaceutical and cosmetic industry. Furthermore, suitable method to separate phenol from waste water is needed. In this research, liquid - liquid extraction method was used with extraction time for 70 minutes. Waste water sample was then separated into two layers which are extract and raffinate. Thereafter, extract and raffinate were then tested by using UV-Vis Spectrophotometer to obtained liquid - liquid equilibrium data. Aim of this research is to study the effect of temperature, stirring speed and type of solvent to obtain distribution coefficient (Kd), phenol yield and correlation of Three-Suffix Margules model for the liquid - liquid extraction data equilibrium. The highest extraction yield at 80.43 % was found by using 70% methanol as solvent at extraction temperature 50 °C with stirring speed 300 rpm, coefficient distribution was found 216.334. From this research it can be concluded that Three-Suffix Margules Model is suitable to predict liquid - liquid equilibrium data for phenol system.

  7. Chem I Supplement: Liquid Crystals--The Chameleon Chemicals.

    Science.gov (United States)

    Brown, Glenn H.

    1983-01-01

    Presents information relevant to everyday life so as to stimulate student interest in the properties of the two basic types of liquid crystals: thermotropic and lyotropic. Describes the applications of liquid crystals to electronics, biomedicine, and polymer science and appraises the future of liquid crystal research. (JM)

  8. 21 CFR 880.2200 - Liquid crystal forehead temperature strip.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Liquid crystal forehead temperature strip. 880... Personal Use Monitoring Devices § 880.2200 Liquid crystal forehead temperature strip. (a) Identification. A liquid crystal forehead temperature strip is a device applied to the forehead that is used to indicate...

  9. Formation of Metastable Crystals from Supercooled, Supersaturated, and Supercompressed Liquids: Role of Crystal-Liquid Interfacial Free Energy

    Directory of Open Access Journals (Sweden)

    Geun Woo Lee

    2017-10-01

    Full Text Available The formation mechanism of metastable crystals from metastable liquids still remains elusive, although controlling the metastability of crystals and liquids already plays a crucial role in designing new materials in physics, chemistry, biology, and materials science. This review article describes how metastable phases can be obtained by controlling temperature, concentration, and pressure. In particular, I show the role of crystal-liquid interfacial free energy in the formation of metastable crystals from metastable liquids at a given driving force. In a microscopic viewpoint, local structure similarity between the metastable crystals and liquid determines the crystal-liquid interfacial free energy, and thus the nucleation barrier for the metastable crystals. The effect of the interfacial free energy on the formation of metastable crystals from supercooled, supersaturated, and supercompressed liquids will be demonstrated with metallic liquids, aqueous solutions, and water.

  10. Experimental measurements of vapor-liquid equilibria of the H2O + CO2 + CH4 ternary system

    Science.gov (United States)

    Qin, J.; Rosenbauer, R.J.; Duan, Zhenhao

    2008-01-01

    Reported are the experimental measurements on vapor-liquid equilibria in the H2O + CO2 + CH4 ternary system at temperatures from (324 to 375) K and pressures from (10 to 50) MPa. The results indicate that the CH4 solubility in the ternary mixture is about 10 % to 40 % more than that calculated by interpolation from the Henry's law constants of the binary system, H2O + CH4, and the solubility of CO2 is 6 % to 20 % more than what is calculated by the interpolation from the Henry's law constants of the binary mixture, H 2O + CO2. ?? 2008 American Chemical Society.

  11. Crystal morphology of binary and ternary mixtures of hydrogenated fats and soybean oil

    Directory of Open Access Journals (Sweden)

    Ilka Sumiyoshi Simões

    2000-01-01

    Full Text Available The objective of this study was to verify the influence of temperature on crystallization of binary and ternary mixtures of two hydrogenated fats and soybean oil, by polarized light microscopy at temperatures of 30° C, 35° C, and 40° C. The types of crystals observed were spherulites type A, and B and the polymorphic forms were ß , and ß -prime. The soybean oil does not contribute statistically to total area or maximum diameter of the crystals. At 35° C the positive relative coefficients to the interactions presented, in general, absolute values higher than the negative ones, pointing that the crystals were larger than what could be expected, if there was no interaction among the components. At 40° C the negative relative coefficients revealed, in general, absolute values higher than the positive ones, indicating that the samples were close to the melting point, showing the presence of some small crystals.Os triacilgliceróis sofrem transições de fase sólido-líquido entre as temperaturas ambiente e corporal, e estas são altamente desejáveis para gorduras que atuam como ingredientes funcionais de alimentos. O objetivo foi estudar a influência da temperatura na cristalização de misturas binárias e ternárias de duas gorduras hidrogenadas e óleo de soja, por microscopia sob luz polarizada, às temperaturas de 30° C, 35° C e 40° C. Os tipos de cristais observados foram esferulitos A e B e as formas polimórficas eram ß e ß -prima. O óleo de soja não contribuiu estatisticamente para a área total ou para o diâmetro máximo dos cristais. A 35° C os coeficientes positivos relativos às interações entre os componentes apresentaram, geralmente, valores absolutos superiores aos negativos, indicando que os cristais eram maiores que o esperado se não houvesse interação. A 40° C os coeficientes negativos relativos às interações apresentaram, geralmente, valores absolutos superiores aos positivos, indicando que as amostras

  12. Particle tracking microrheology of lyotropic liquid crystals.

    Science.gov (United States)

    Alam, Mohammad Mydul; Mezzenga, Raffaele

    2011-05-17

    We present comprehensive results on the microrheological study of lyotropic liquid crystalline phases of various space groups constituted by water-monoglyceride (Dimodan) mixtures. In order to explore the viscoelastic properties of these systems, we use particle tracking of probe colloidal particles suitably dispersed in the liquid crystals and monitored by diffusing wave spectroscopy. The identification of the various liquid crystalline phases was separately carried out by small-angle X-ray scattering. The restricted motion of the particles was monitored and identified by the decay time of intensity autocorrelation function and the corresponding time-dependent mean square displacement (MSD), which revealed space group-dependent behavior. The characteristic time extracted by the intersection of the slopes of the MSD at short and long time scales, provided a characteristic time which could be directly compared with the relaxation time obtained by microrheology. Further direct comparison of microrheology and bulk rheology measurements was gained via the Laplace transform of the generalized time-dependent MSD, yielding the microrheology storage and loss moduli, G'(ω) and G''(ω), in the frequency domain ω. The general picture emerging from the microrheology data is that all liquid crystals exhibit viscoelastic properties in line with results from bulk rheology and the transition regime (elastic to viscous) differs according to the specific liquid crystal considered. In the case of the lamellar phase, a plastic fluid is measured by bulk rheology, while microrheology indicates viscoelastic behavior. Although we generally find good qualitative agreement between the two techniques, all liquid crystalline systems are found to relax faster when studied with microrheology. The most plausible explanation for this difference is due to the different length scales probed by the two techniques: that is, microscopical relaxation on these structured fluids, is likely to occur at

  13. The sweet world of liquid crystals : The synthesis of non-amphiphilic carbohydrate-derived liquid crystals

    NARCIS (Netherlands)

    Smits, E

    1998-01-01

    The research in carbohydrate-derived liquid crystals was initiated by a review article by Jeffrey in 1986. This is rather late if one considers that the research on liquid crystals underwent a revival already in the 1960s after the discovery of the liquid crystal display (LCD). Carbohydrates were

  14. Topological defects in cholesteric liquid crystal shells.

    Science.gov (United States)

    Darmon, Alexandre; Benzaquen, Michael; Čopar, Simon; Dauchot, Olivier; Lopez-Leon, Teresa

    2016-11-23

    We investigate experimentally and numerically the defect configurations emerging when a cholesteric liquid crystal is confined to a spherical shell. We uncover a rich scenario of defect configurations, some of them non-existent in nematic shells, where new types of defects are stabilized by the helical ordering of the liquid crystal. In contrast to nematic shells, here defects are not simple singular points or lines, but have a large structured core. Specifically, we observe five different types of cholesteric shells. We study the statistical distribution of the different types of shells as a function of the two relevant geometrical dimensionless parameters of the system. By playing with these parameters, we are able to induce transitions between different types of shells. These transitions involve interesting topological transformations in which the defects recombine to form new structures. Surprisingly, the defects do not approach each other by taking the shorter distance route (geodesic), but by following intricate paths.

  15. Design considerations for liquid crystal contact lenses

    Science.gov (United States)

    Bailey, J.; Kaur, S.; Morgan, P. B.; Gleeson, H. F.; Clamp, J. H.; Jones, J. C.

    2017-12-01

    Switchable liquid crystal contact lenses with electrically controllable focal powers have previously been investigated as an alternative to bifocal contact lenses and spectacles for the correction of presbyopia. The simplest lens design uses a meniscus shaped cavity within the lens to contain the liquid crystal. The design of such a lens is considered in detail, including the nematic alignment and electrodes materials. The organic transparent conductor PEDOT:PSS was used as both electrode and planar alignment. Four different configurations are considered, using both planar and homeotropic orientations with either homogenous or axial alignment. Controllable switching of the focal power was demonstrated for each mode and focal power changes of up to ΔP  =  3.3  ±  0.2 D achieved. Such lens designs offer significant potential for a novel form of correction for this common visual problem.

  16. Carbon nanotubes dispersed in liquid crystal elastomers

    Science.gov (United States)

    Yang, Yang; Ji, Yan

    Liquid crystal elastomers (LCEs), as the name indicates, unite the anisotropic order of liquid crystals and rubber elasticity of elastomers into polymer networks. One of the most notable features of LCEs is that properly aligned LCEs exhibit dramatic and reversible shape deformation (e.g. elongation-contraction) in response to various stimuli. In recent years, carbon nanotubes (CNTs) were introduced into LCEs. Besides enabling remote and spatial control of the actuation via light and electronic field, CNTs are also utilized to align mesogens as well as to improve the mechanical and electronic property of the composites. Some potential applications of CNT-LCE nanocomposites have been demonstrated. This chapter describes the preparation of CNT dispersed LCEs, new physical properties resulted from CNTs, their actuation and their proposed applications.

  17. Biaxial nematic liquid crystals theory, simulation and experiment

    CERN Document Server

    Luckhurst, Geoffrey R

    2015-01-01

    Liquid Crystals are a state of matter that have properties between those of conventional liquid and those of a solid crystal. Thermotropic liquid crystals react to changes in temperature or, in some cases, pressure. The reaction of lyotropic liquid crystals, which are used in the manufacture of soaps and detergents, depends on the type of solvent they are mixed with. Since the accidental discovery of the chiral nematic (ordered) phase in 1888 many liquid crystal phases have been found, sometimes by chance and sometimes by design. The existence of one such phase was predicted by Freiser in 197

  18. Spectral characterization, crystal structures and biological activities of iminodiacetate ternary complexes

    Science.gov (United States)

    Shahid, M.; Anjuli; Tasneem, Sana; Mantasha, I.; Ahamad, M. Naqi; Sama, Farasha; Fatma, Kehkeshan; Siddiqi, Zafar A.

    2017-10-01

    The ternary complexes with stoichiometry [M(imda)(bipy)]·6H2O (M = Cu) and [M(imda)(bipy)(H2O)]·4H2O (M = Ni, Co and Mn) where H2imda = iminodiacetic acid and bipy = 2,2‧-bipyridine, are prepared and characterized to exploit as novel antimicrobial agents and SOD mimics. The chemical structures were elucidated by IR, FAB-Mass, 1H, 13C NMR, EPR and spectral techniques. Single crystal X-ray and spectral studies of the complexes (1) and (2) have confirmed a square pyramidal geometry around Cu(II) ion while a saturated six coordinate (distorted octahedral) geometry around the Ni(II), Co(II) and Mn(II) ions due to the additional coordination from water. A supramolecular network is formed by extensive H-bonding in complex (1). The supramolecular assembly in complex (1) is additionally consolidated via the existence of unusual cyclic hexameric water clusters. The antimicrobial activities for the present complexes have been examined against Escherichia coli (K-12), Bacillus subtilis (MTC-121), Staphylococcus aureus (IOASA-22), Salmonella typhymurium (MTCC-98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei. The superoxide dismutase (SOD) activity of the Cu(II) complex (1) is also assessed employing nitrobluetetrazolium (NBT) assay.

  19. Optical Power Limiting Liquid Crystal Composites

    Science.gov (United States)

    1994-11-10

    Kent, Ohio 44242-0001 Ba. NAME OF FUNDING/SPONSORING Bb. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If aplicable ) Fy/gl...Results Tabulation 119 4 2 Introduction This research effort carried out a wide range of investigations of both linear and nonlinear optical phenomena in...due to self-defocusing of the beam by the liquid crystal sample. The damage is produced on the interior surface of the glass; there is no apparent

  20. Fast-Response Liquid Crystal Microlens

    Directory of Open Access Journals (Sweden)

    Su Xu

    2014-06-01

    Full Text Available Electrically tunable liquid crystal microlenses have attracted strong research attention due to their advantages of tunable focusing, voltage actuation, low power consumption, simple fabrication, compact structure, and good stability. They are expected to be essential optical devices with widespread applications. However, the slow response time of nematic liquid crystal (LC microlenses has been a significant technical barrier to practical applications and commercialization. LC/polymer composites, consisting of LC and monomer, are an important extension of pure LC systems, which offer more flexibility and much richer functionality than LC alone. Due to the anchoring effect of a polymer network, microlenses, based on LC/polymer composites, have relatively fast response time in comparison with pure nematic LC microlenses. In addition, polymer-stabilized blue phase liquid crystal (PS-BPLC based on Kerr effect is emerging as a promising candidate for new photonics application. The major attractions of PS-BPLC are submillisecond response time and no need for surface alignment layer. In this paper, we review two types of fast-response microlenses based on LC/polymer composites: polymer dispersed/stabilized nematic LC and polymer-stabilized blue phase LC. Their basic operating principles are introduced and recent progress is reviewed by examples from recent literature. Finally, the major challenges and future perspectives are discussed.

  1. Synthesis, Crystal Structure, and Characterization of Ternary Copper(II Complex Derived from N-(salicylidene-L-valine

    Directory of Open Access Journals (Sweden)

    Sundaramurthy Santha Lakshmi

    2016-01-01

    Full Text Available Ternary Schiff base copper(II complex [CuL(tmpda] (where H2L is N-(salicylidene-L-valine; tmpda is N,N,N′,N′-tetramethyl-1,3-propanediamine has been characterized by UV-Vis., FTIR, and single crystal XRD. The crystal structure displays a distorted square pyramidal geometry in which Schiff base is bonded to the Cu(II ion via phenolate oxygen, imine nitrogen, and an oxygen atom of the carboxylate group through the basal plane and the chelating diamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, displays an axial and equatorial mode of binding via NN-donor atoms.

  2. Liquid Crystal Elastomer Actuators from Anisotropic Porous Polymer Template.

    Science.gov (United States)

    Wang, Qian; Yu, Li; Yu, Meina; Zhao, Dongyu; Song, Ping; Chi, Hun; Guo, Lin; Yang, Huai

    2017-08-01

    Controlling self-assembly behaviors of liquid crystals is a fundamental issue for designing them as intelligent actuators. Here, anisotropic porous polyvinylidene fluoride film is utilized as a template to induce homogeneous alignment of liquid crystals. The mechanism of liquid crystal alignment induced by anisotropic porous polyvinylidene fluoride film is illustrated based on the relationship between the alignment behavior of liquid crystals and surface microstructure of anisotropic polyvinylidene fluoride film. Liquid crystal elastomer actuators with fast responsiveness, large strain change, and reversible actuation behaviors are achieved by the photopolymerization of liquid crystal monomer in liquid crystal cells coated with anisotropic porous films. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Properties of the Band Gaps in 1D Ternary Lossy Photonic Crystal Containing Double-Negative Materials

    Directory of Open Access Journals (Sweden)

    Alireza Aghajamali

    2014-01-01

    Full Text Available Theoretically, the characteristics matrix method is employed to investigate and compare the properties of the band gaps of the one-dimensional ternary and binary lossy photonic crystals which are composed of double-negative and double-positive materials. This study shows that by varying the angle of incidence, the band gaps for TM and TE waves behave differently in both ternary and binary lossy structures. The results demonstrate that, by increasing the angle of incidence for the TE wave, the width and the depth of zero-n¯, zero-μ, and Bragg gap increase in both ternary and binary structures. On the other hand, the enhancement of the angle of incidence for the TM wave contributes to reduction of the width and the depth of the zero-n¯ and Bragg gaps, and they finally disappear for incidence angles greater than 50° and 60° for the binary structure and 40° and 45° for the ternary structures, respectively. In addition, the details of the edges of the band gaps variations as a function of incidence angle for both structures are studied.

  4. Liquid-liquid equilibria for binary and ternary systems containing glycols, aromatic hydrocarbons, and water: Experimental measurements and modeling with the CPA EoS

    DEFF Research Database (Denmark)

    Folas, Georgios; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2006-01-01

    Liquid-liquid equilibrium data of four binary glycol + aromatic hydrocarbon systems and three ternary systems containing water have been measured at atmospheric pressure. The measured systems are monoethylene glycol (MEG) + benzene or toluene, triethylene glycol (TEG) + benzene or toluene, MEG...... + water + benzene, MEG + water + toluene, and TEG + water + toluene. The binary systems are correlated with the Cubic-Plus-Association (CPA) equation of state while the ternary systems are predicted from interaction parameters obtained from the binary systems. Very satisfactory liquid-liquid equilibrium...... correlations are obtained for the binary systems using temperature-independent interaction parameters, while adequate predictions are achieved for multicomponent water + glycol + aromatic hydrocarbons systems when accounting for the solvation between the aromatic hydrocarbons and glycols or water....

  5. The micro-flow reaction system featured the liquid-liquid interface created with ternary mixed carrier solvents in a capillary tube.

    Science.gov (United States)

    Masuhara, Yuji; Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2012-01-01

    A micro-flow reaction system was developed in which liquid-liquid interface was created based on the tube radial distribution of ternary mixed carrier solvents. The system was constructed from double capillary tubes having different inner diameters (100 and 250 µm i.d.). The smaller tube was inserted into the larger one through a T-type joint. The reaction of a protein with a fluorescence derivatizing reagent was adopted as a model. A water-acetonitrile mixture (3:1 volume ratio) including bovine serum albumin (hydrophilic) was delivered into the large tube from the inside through the small tube and an acetonitrile-ethyl acetate mixture (7:4 volume ratio) containing fluorescamine (hydrophobic) as a derivatizing reagent was delivered from the outside through the joint. Solutions were mixed through the double capillary tubes to promote ternary mixed carrier solvents (water-acetonitrile-ethyl acetate; 1:2:1 volume ratio). The liquid-liquid interface was created based on the tube radial distribution of ternary solvents in the larger tube. The derivatization reaction was performed in the larger, or reaction, tube in the micro-flow system. The fluorescence intensity of the fluorescamine-derivatized bovine serum albumin obtained by the system, which specifically included the kinetic liquid-liquid interface in the tube, was greater than that obtained through a batch reaction using a homogeneous solution of water-acetonitrile (1:2 volume ratio).

  6. Liquid crystal parameter analysis for tunable photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2010-01-01

    We investigate the tunability of splay-aligned liquid crystals for the use in solid core photonic crystal fibers. Finite element simulations are used to obtain the alignment of the liquid crystals subject to an external electric field. By means of the liquid crystal director field the optical...... permittivity is calculated and used in finite element mode simulations. The suitability of liquid crystal photonic bandgap fiber devices for filters, waveplates or sensors is highly dependent on the tunability of the transmission spectrum. In this contribution we investigate how the bandgap tunability...... is determined by the parameters of the liquid crystals. This enables us to identify suitable liquid crystals for tunable photonic bandgap fiber devices...

  7. Temperature independent low voltage polymer stabilized blue phase liquid crystals

    Science.gov (United States)

    Kemiklioglu, E.; Hwang, J. Y.; Chien, L.-C.

    2012-03-01

    Blue phases are types of liquid crystal phase which can appear in a narrow temperature range between a chiral nematic phase and isotropic liquid phase. Blue Phase (BP) liquid crystals have been known to exist in a small temperature range. Recently, broadening the temperature range of a BP liquid crystal has occurred by using a mixture of nematic bimesogenic liquid crystals or by polymerizing a small amount of monomer in a BP to stabilize the cubic lattice against temperature variation. In this study, we report a low switching voltage polymer stabilized blue phase (PSBP) liquid crystal device. We showed the stabilization of blue phases over a temperature range of 30.4 °C including room temperature. We observed the temperature independent of Bragg wavelength. Furthermore, the polymer effect on the electo-optic properties of a self assembled nanostructured blue phase liquid crystal composites have been investigated. As well as the ratio between two monomers, the overall monomers concentration is controlled.

  8. Electrically tunable liquid crystal photonic bandgap fiber laser

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei

    2010-01-01

    We demonstrate electrical tunability of a fiber laser by using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all...

  9. Liquid crystal nanocomposites produced by mixtures of hydrogen bonded achiral liquid crystals and functionalized carbon nanotubes

    Science.gov (United States)

    Katranchev, B.; Petrov, M.; Keskinova, E.; Naradikian, H.; Rafailov, P. M.; Dettlaff-Weglikowska, U.; Spassov, T.

    2014-12-01

    The liquid crystalline (LC) nature of alkyloxybenzoic acids is preserved after adding of any mesogenic or non-mesogenic compound through hydrogen bonding. However, this noncovalent interaction provokes a sizable effect on the physical properties as, e. g. melting point and mesomorphic states. In the present work we investigate nanocomposites, prepared by mixture of the eighth homologue of p-n-alkyloxybenzoic acids (8OBA) with single-walled carbon nanotubes (SWCNT) with the purpose to modify the optical properties of the liquid crystal. We exercise optical control on the LC system by inserting SWCNT specially functionalized by carboxylic groups. Since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level, molecular modification can lead to different macroscopical nanocomposite symmetry. The thermal properties of the functionalized nanocomposite are confirmed by DSC analyses. The mechanism of the interaction between surface-treated nanoparticles (functionalized nanotubes) and the liquid crystal 8OBA bent- dimer molecules is briefly discussed.

  10. Perdeuterated liquid crystals for near infrared applications

    Science.gov (United States)

    Kula, P.; Bennis, N.; Marć, P.; Harmata, P.; Gacioch, K.; Morawiak, P.; Jaroszewicz, L. R.

    2016-10-01

    For majority of Liquid Crystalline compounds the absorption occurs at two spectral regions: ultraviolet UV (due to electronic excitations) and infrared IR (caused by molecular vibrations). Both cause the absorption which deteriorates electro-optical modulation abilities of LC. In the MWIR and LWIR regions, there are many fundamental molecular vibration bands. The most intense are the ones with high anharmonicity, which in the case of LCs corresponds to the Csbnd H bonds, especially present in the aliphatic chains. In the NIR region, overtone molecular vibration bands derived from IR region begin to appear. In the case of Csbnd H bond system, the first overtones are present at 1.6-1.7 μm. To reduce NIR absorptions, perdeuterated Liquid crystal has been proposed. In this paper, we report the physical and optical properties of liquid crystals based on polarimetry measurements method. We also provide a polar decomposition of experimentally measured Mueller matrix in order to determine polarization properties of the device such as depolarization and diattenuation which cannot be obtained from absorption spectra.

  11. Smectic phases in ionic liquid crystals.

    Science.gov (United States)

    Bartsch, Hendrik; Bier, Markus; Dietrich, S

    2017-11-22

    Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry charges and therefore combine properties of liquid crystals, e.g. the formation of mesophases, and of ionic liquids, such as low melting temperatures and tiny triple-point pressures. Previous density functional calculations have revealed that the phase behavior of ILCs is strongly affected by their molecular properties, i.e. their aspect ratio, the loci of the charges, and their interaction strengths. Here, we report new findings concerning the phase behavior of ILCs as obtained by density functional theory and Monte Carlo simulations. The most important result is the occurrence of a novel, wide smectic-A phase [Formula: see text], at low temperature, the layer spacing of which is larger than that of the ordinary high-temperature smectic-A phase [Formula: see text]. Unlike the ordinary smectic S A phase, the structure of the [Formula: see text] phase consists of alternating layers of particles oriented parallel to the layer normal and oriented perpendicular to it.

  12. Phototropic liquid crystal materials containing naphthopyran dopants

    Science.gov (United States)

    Rumi, Mariacristina; Cazzell, Seth; Kosa, Tamas; Sukhomlinova, Ludmila; Taheri, Bahman; Bunning, Timothy; White, Timothy

    2015-03-01

    Dopant molecules dispersed in a liquid crystalline material usually affects the order of the system and the transition temperature between various phases. If the dopants undergo photoisomerization between conformers with different shapes, the interactions with the liquid crystal molecules can be different for the material in the dark and during exposure to light of appropriate wavelength. This can be used to achieve isothermal photoinduced phase transitions (phototropism). With proper selection of materials components, both order-to-disorder and disorder-to-order photoinduced transition have been demonstrated. Isothermal order-increasing transitions have been observed recently using naphthopyran derivatives as dopants. We are investigating the changes in order parameter and transition temperature of liquid crystal mixtures containing naphthopyrans and how they are related to exposure conditions and to the concentration and molecular structure of the dopants. We are also studying the nature of the photoinduced phase transitions, and comparing the behavior with that of azobenzene-doped mixtures, in which exposure to light leads to a decrease, instead of an increase, in the order of the system.

  13. Poincaré-sphere representation of phase-mostly twisted nematic liquid crystal spatial light modulators

    Science.gov (United States)

    Durán, V.; Clemente, P.; Martínez-León, Ll; Climent, V.; Lancis, J.

    2009-08-01

    We establish necessary conditions in order to build a phase-only wavefront modulation system from a liquid crystal display. These conditions determine the dependence of the polarization state of the light emerging from the display on the addressing gray level. The analysis, which is carried out by means of the coherence-matrix formalism, includes the depolarization properties of the device. Two different types of polarization distributions at the output of the liquid crystal cells are found. This approach is applied to a twisted nematic liquid crystal display. In this case, an optimization algorithm must be designed in order to select the input polarization state that leads to the required distributions. We show that the Poincaré-sphere representation provides a convenient framework to design the optimization algorithm as it allows for a reduced number of degrees of freedom. This feature significantly decreases the computation time. Laboratory results are presented for a liquid crystal on silicon display showing a phase modulation depth greater than 2π rad with an intensity variation lower than 6%. In addition, a hybrid ternary modulation (HTM), an operation regime employed in holographic data storage, is achieved.

  14. Solid–liquid equilibria for binary and ternary systems with the Cubic-Plus-Association (CPA) equation of state

    DEFF Research Database (Denmark)

    Fettouhi, André; Thomsen, Kaj

    2010-01-01

    A systematic investigation of the CPA model's performance within solid-liquid equilibria (SLE) in binary mixtures (methane + ethane, methane + heptane, methane + benzene, methane + CO2, ethane + heptane, ethane + CO2, 1-propanol + 1,4-dioxane, ethanol + water, 2-propanol + water) is presented. Th....... The results from the binary mixtures are used to predict SLE behaviour in ternary mixtures (methane + ethane + heptane, methane + ethane + CO2). Our results are compared with experimental data found in the literature....

  15. (Liquid + liquid) equilibrium for ternary mixtures of {l_brace}heptane + aromatic compounds + [EMpy][ESO{sub 4}]{r_brace} at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Mirkhani, S.A. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Vossoughi, M., E-mail: vosoughi@sharif.edu [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Pazuki, G.R. [Department of Chemical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Safekordi, A.A. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Heydari, A.; Akbari, J. [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Yavari, M. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2011-10-15

    Highlights: > This paper reports the LLE data of ternary systems {l_brace}heptane (1) + aromatic compounds (2) + [EMpy][ESO{sub 4}] (3){r_brace}. > The distribution coefficient and the selectivity were obtained from the experimental data. > The consistency of LLE data was successfully correlated with Othmer-Tobias and Hand equation. - Abstract: (Liquid + liquid) equilibrium (LLE) data for the ternary systems (heptane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate) and (heptane + benzene + 1-ethyl-3-methylpyridinium ethylsulfate) were measured at T = 298.15 K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of aromatic compounds from heptane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations.

  16. Ternary (liquid + liquid) equilibria of (diethyl carbonate + ethanol or 1-propanol + water) systems at 303.15 K under atmospheric pressure

    Science.gov (United States)

    Ginting, Rizqy Romadhona; Mustain, Asalil; Gunardi, Ignatius; Wibawa, Gede

    2017-01-01

    Ternary (liquid + liquid) equilibria data of diethyl carbonate (DEC) + ethanol or 1-propanol + water systems were accurately determined at 303.15 K using jacketed equilibrium cell under atmospheric pressure. The reliability of experimental tie-line data were checked by using Bachman-Brown correlation giving an r-squared value of 0.9933 and 0.9996, respectively. Both systems studied in this work exhibit Treybal's Type I ternary phase behavior. The experimental tie-line data were correlated well using the Non-Random Two Liquid (NRTL) and Universal Quasi-Chemical (UNIQUAC) activity coefficient models giving root-mean-square deviation (RMSD) of 0.95 and 1.18% for DEC + ethanol + water system.,While DEC + 1-propanol + water system gives RMSD value of 0.30 and 0.37%, respectively. The effect of carbon chain length of alcohol to the phase boundary of both systems was observed and discussed in detail.

  17. New triazolium based ionic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Stappert, Kathrin [Ruhr-Universitat Bochum; Unal, Derya [Ruhr-Universitat Bochum; Mallick, Bert [Ruhr Universitat Bochum; Mudring, Anja-Verena [Ames Laboratory

    2014-01-01

    A set of novel 1,2,3-triazolium based ionic liquid crystals was synthesized and their mesomorphic behaviour studied by DSC (differential scanning calorimetry), POM (polarizing optical microscopy) and SAXS (small angle X-ray scattering). Beside the variation of the chain length (C10, C12 and C14) at the 1,2,3-triazolium cation also the anion has been varied (Br-, I-, I3-, BF4-, SbF6-, N(CN)2-, Tf2N-) to study the influence of ion size, symmetry and H-bonding capability on the mesophase formation. Interestingly, for the 1,3-didodecyl-1,2,3-triazolium cation two totally different conformations were found in the crystal structure of the bromide (U-shaped) and the triiodide (rod shaped).

  18. Liquid Crystals and Photonic Bandgap Fiber Components

    DEFF Research Database (Denmark)

    Weirich, Johannes; Wei, Lei; Scolari, Lara

    Liquid Crystal(LC)filled Photonic Crystal Fibers(PCFs) represent a promising platform for the design and the fabrication of tunable all-in fiber devices. Tunability is achieved by varying the refractive index of the LC thermally, optically or electrically. In this contribution we present important...... parts of the LC theory as well as an application of a LC infiltrated PCF subject to an external electrostatic field. The fiber is placed between two electrodes and the voltage is increased step by step leading to the reorientation of the LC in the fiber capillaries. This mechanism can be used to produce...... a swichable polarizer, and an on chip LC photonic bandgap fiber polarimeter is presented, which admits strong attenuation of one polarization direction while the other one is nearly unaffected....

  19. Successive Transitions in Cholesteric Liquid Crystals

    Science.gov (United States)

    Hirata, Shoji; Matsuzaki, Ichiro; Yanagita, Akihiro; Tako, Toshiharu

    1981-12-01

    Successive transitions in an AC electric field in cholesteric liquid crystals with negative dielectric anisotropy have been investigated systematically. According to the relations between the frequency of applied AC field and the threshold voltage Vth of successive transitions and between Vth and cell thickness divided by cholesteric pitch D/P0 several features are observed. The threshold voltage for the dielectric regime extends to a DC electric regime. Quenching of the conduction regime is observed in a thinner sample cell. Some curious behaviors of the domain corresponding to the dielectric regime are also observed. A new model which can explain the mechanism of successive transitions in conduction regime is proposed.

  20. Interference coloring by polymer dispersed liquid crystals

    Science.gov (United States)

    Maksimyak, P. P.; Nehrych, A. L.

    2015-11-01

    We analyze the effects of coloring of a beam traversing a light-scattering medium. Spectral investigation of the effects of coloring has been carried out using a solution of liquid crystal in a polymer matrix (PDLC). It is shown that the result of coloring of the beam at the output of the medium depends on the magnitudes of the phase delays of the singly forward scattered partial signals. We consider the influence of interference coloring effect on the transmission scattering and spatial-frequency filtering of the radiation which has passed through the PDLC.

  1. Laser damage resistant nematic liquid crystal cell

    Science.gov (United States)

    Raszewski, Z.; Piecek, W.; Jaroszewicz, L.; Soms, L.; Marczak, J.; Nowinowski-Kruszelnicki, E.; Perkowski, P.; Kedzierski, J.; Miszczyk, E.; Olifierczuk, M.; Morawiak, P.; Mazur, R.

    2013-08-01

    There exists a problem in diagnostics of a dense plasma (so-called Thomson diagnostics). For this purpose, the plasma is illuminated by series of high energy laser pulses. Such pulses are generated by several independent lasers operating sequentially, and these pulses are to be directed along an exactly the same optical path. In this case, the energy of each separate pulse is as large as 3 J, so it is impossible to generate a burst of such pulses by a single laser. In this situation, several independent lasers have to be used. To form optical path with λ = 1.064 μm and absolute value of the energy of laser pulse through of 3 J, a special refractive index matched twisted Nematic Liquid Crystal Cell (NLCC) of type LCNP2 with switching on time τON smaller than 5 μs might be applied. High laser damage resistance of NLCC and short τON can be fulfilled by preparation of liquid crystal cells with Liquid Crystal Mixture (LCM), well tuned to twisted nematic electro-optical effect, and well tuned all optical interfaces (Air - Antireflection - Quartz Plate - Electrode - Blocking Film - Aligning Layer - LCM - Aligning Layer - Blocking Film - Electrode - Quartz Plate - Antireflection - Air). In such LCNP2 cell, the transmission is higher than 97% at λ = 1.064 μm, as it is presented by Gooch and Tarry [J. Phys. D: Appl. Phys. 8, 1575 (1975)]. The safe laser density energy is about 0.6 J/cm2 for a train of laser pulses (λ = 1.064 μm, pulse duration 10 ns FWHM, pulse repetition rate 100 pps, train duration 10 s), so the area of liquid crystal cell tolerating 3 J through it shall be as large as 5 cm2. Due to the presence of two blocking film layers between electrodes, LCNP2 can be driven by high voltages. Switching on time smaller than τON = 5 μs was obtained under 200 V switching voltage.

  2. Liquid crystals for holographic optical data storage

    DEFF Research Database (Denmark)

    Matharu, Avtar; Jeeva, S.; Ramanujam, P.S.

    2007-01-01

    A tutorial review is presented to inform and inspire the reader to develop and integrate strong scientific links between liquid crystals and holographic data storage, from a materials scientist's viewpoint. The principle of holographic data storage as a means of providing a solution...... to the information storage demands of the 21st century is detailed. Holography is a small subset of the much larger field of optical data storage and similarly, the diversity of materials used for optical data storage is enormous. The theory of polarisation holography which produces holograms of constant intensity...

  3. Nanoparticle-doped isotropic liquid crystals

    Science.gov (United States)

    Parfenov, Alexander; Xia, Xiaowei; Shapoury, Alireza; DeHoog, Edward A.; Zhang, Fang; Pradhan, Shilpa; Aye, Tin M.; Shih, Min-Yi; Hall, Arlynn Z.; Cooper, Thomas M.

    2011-10-01

    We demonstrate a new material composed of isotropic liquid crystal (ILC) blended with semiconductor nanoparticles, which could result in a novel high-speed, multiple-notch broadband passive optical switch to selectively discriminate bands of electromagnetic radiation in intelligence, surveillance, or reconnaissance systems. The new material has been demonstrated high nonlinear 3rd order optical Kerr coefficients (light-induced refractive index change, n2) exceeding 100 times of classic nonlinear material CS2 with n2 = 1.2E-11 esu. Details of fabrication and experimental results are presented.

  4. Liquid crystal photoalignment: history and future

    Science.gov (United States)

    Chigrinov, V. G.; Kwok, H. S.; Takada, Hirokazu; Takatsu, Haruyoshi

    2007-02-01

    In this original review we briefly consider the novel azo-dye photo-aligning technology: history and the perspectives for future applications in liquid crystal (LC) devices. The review describes the following items. The brief introduction to the history of photoalignment and the basic classes of the photoaligning materials: photosensitive polymers, azodyes and monolayers will follow with an introduction to the physical mechanisms of the photo-aligning and photo-patterning technology. The advantages and drawbacks of various photo-aligning materials are analyzed from the point of view of practical applications. The detail description of the diffusion photo-aligning in azo-dye materials is provided. The characteristics of azo-dye photoaligning LC layers are compared with those ones prepared by polyimide rubbing method. The characterization of LC-surface interaction, such as pretilt angle and azimuthal anchoring energy is discussed. The newly developed materials should have a controllable pretilt angle and anchoring energy, thus enabling to develop a new generation of the LC devices: with low voltage, fast response and wide viewing angles. The problem of image sticking can be considerably reduced due to the high anchoring energy of azo-dye materials. Promising results, obtained for voltage holding Ratio (VHR) and residual DC voltage (RDC) in azodye photo-aligning materials are also shown. This implies that the azo-dyes can be applied as aligning layers in active matrix liquid crystal displays (AM-LCDs). The possibility to use the photo-aligning layers for new types of liquid crystal displays such as FLCD, VAN-LCD, π-BTN LCD, optical rewritable memory, microdisplays, and TN-LCD on plastic substrates is demonstrated. The photoaligning of liquid crystal polymers (LCP) and the new classes of devices based on them (optical retarders and compensators) is discussed. Special types of 3D LC alignment, LC alignment inside thin micro tubes, and grating surface were concerned

  5. Tuning Fluidic Resistance via Liquid Crystal Microfluidics

    Directory of Open Access Journals (Sweden)

    Anupam Sengupta

    2013-11-01

    Full Text Available Flow of molecularly ordered fluids, like liquid crystals, is inherently coupled with the average local orientation of the molecules, or the director. The anisotropic coupling—typically absent in isotropic fluids—bestows unique functionalities to the flowing matrix. In this work, we harness this anisotropy to pattern different pathways to tunable fluidic resistance within microfluidic devices. We use a nematic liquid crystalline material flowing in microchannels to demonstrate passive and active modulation of the flow resistance. While appropriate surface anchoring conditions—which imprint distinct fluidic resistances within microchannels under similar hydrodynamic parameters—act as passive cues, an external field, e.g., temperature, is used to actively modulate the flow resistance in the microfluidic device. We apply this simple concept to fabricate basic fluidic circuits, which can be hierarchically extended to create complex resistance networks, without any additional design or morphological patterning of the microchannels.

  6. Ternary liquid mixtures control the multiplicity, shape and internal structure of emulsion droplets

    Science.gov (United States)

    Haase, Martin F.; Brujic, Jasna

    2014-03-01

    It is important to control the shape, internal structure and stability of emulsion droplets for drug delivery, biochemical assays, and the design of materials with novel physical properties. Successful methods involve the mechanical manipulation of the flow of oil in water using complex microfluidic devices to make multiple emulsions with a sequential introduction of specific reactants. Instead, here we show how the thermodynamics of immiscible liquid mixtures tailor emulsions using a single dripping instability. For example, the initial composition and choice of surfactant govern the multiplicity of concentric alternating oil and water layers inside the droplets. Stabilizing ternary droplets using nanoparticles gives rise to a plethora of shapes whose geometry is defined by the deformability of the shell and the flow rate. Another option is to incorporate lipids to the multiple emulsion droplet, which form vesicles upon expulsion of the inner water droplets. Depending on the number of initial water droplets, these vesicles eventually form complex hollow topologies, which can be used as junctions or scaffolds for the self-assembly of colloidal particles in the future.

  7. Solubility measurement and solid-liquid equilibrium model for the ternary system MgBr2 + MgSO4 + H2O at 288.15 K

    Directory of Open Access Journals (Sweden)

    Li Dan

    2014-06-01

    Full Text Available The solubility of magnesium minerals and the refractive index of the ternary system MgBr2 + MgSO4 + H2O at 288.15 K were investigated using an isothermal dissolution method. It was found that there are two invariant points in the phase diagram and the solubility isotherm of this ternary system consists of three branches, corresponding to equilibrium crystallization of Epsomite (MgSO4·7H2O, Eps, hexahydrite (MgSO4·6H2O, Hex and magnesium bromide hexahydrate (MgBr2·6H2O, Mb. Neither solid solutions nor double salts were found. The refractive indices calculated from empirical equation are in good agreement with the experimental data. Combining the results from solubility measurements with the single-salt parameters for MgBr2 and MgSO4, and the mixed ion-interaction parameter θBr,S0(4, the parameter ψMg,Br,S0(4 at 288.15 K was fitted using the Pitzer theory and Harvie-Weare (HW approach. In addition, the average equilibrium constants of the stable equilibrium solids at 288.15 K were obtained by a method using the activity product constant. A chemical model, which combined the Pitzer parameters and the average equilibrium constants, was constructed to calculate the solid + liquid equilibria in the ternary system MgBr2 + MgSO4 + H2O at 288.15 K. The model agreed well with the equilibrium solubility data for the magnesium salts.

  8. Partially exposed polymer dispersed liquid crystals for boundary layer investigations

    Science.gov (United States)

    Parmar, Devendra S.; Singh, Jag J.

    1992-01-01

    A new configuration termed partially exposed polymer dispersed liquid crystal in which the liquid crystal microdroplets dispersed in a rigid polymer matrix are partially entrapped on the free surface of the thin film deposited on a glass substrate is reported. Optical transmission characteristics of the partially exposed polymer dispersed liquid crystal thin film in response to an air flow induced shear stress field reveal its potential as a sensor for gas flow and boundary layer investigations.

  9. A microstructure-composition map of a ternary liquid/liquid/particle system with partially-wetting particles.

    Science.gov (United States)

    Yang, Junyi; Roell, David; Echavarria, Martin; Velankar, Sachin S

    2017-11-22

    We examine the effect of composition on the morphology of a ternary mixture comprising two molten polymeric liquid phases (polyisobutylene and polyethylene oxide) and micron-scale spherical silica particles. The silica particles were treated with silanes to make them partially wetted by both polymers. Particle loadings up to 30 vol% are examined while varying the fluid phase ratios across a wide range. Numerous effects of particle addition are catalogued, stabilization of Pickering emulsions and of interfacially-jammed co-continuous microstructures, meniscus-bridging of particles, particle-induced coalescence of the dispersed phase, and significant shifts in the phase inversion composition. Many of the effects are asymmetric, for example particle-induced coalescence is more severe and drop sizes are larger when polyisobutylene is the continuous phase, and particles promote phase continuity of the polyethylene oxide. These asymmetries are likely attributable to a slight preferential wettability of the particles towards the polyethylene oxide. A state map is constructed which classifies the various microstructures within a triangular composition diagram. Comparisons are made between this diagram vs. a previous one constructed for the case when particles are fully-wetted by polyethylene oxide.

  10. Study of the ternary system Al-H-RE (RE = Er, La and Y) in liquid state

    OpenAIRE

    Prigent, Jocelyn; Joubert, Jean-Marc; Latroche, Michel

    2016-01-01

    Hydrogen is the only gas able to dissolve in aluminum. The solubility S of hydrogen in Al obeys the Sieverts’ law and S is much larger in the liquid phase (above 660.4°C) than in the solid one. This might lead to the formation of porosity during aluminum casting. In the present work, the ternary system Al-H-RE (RE= Er, La, Y) is investigated. The equilibria between the different phases are determined in the presence of liquid Al, RE and H2 gas by both experimental measurements and phase diagr...

  11. Application of artificial neural network for vapor liquid equilibrium calculation of ternary system including ionic liquid: Water, ethanol and 1-butyl-3-methylimidazolium acetate

    Energy Technology Data Exchange (ETDEWEB)

    Fazlali, Alireza; Koranian, Parvaneh [Arak University, Arak (Iran, Islamic Republic of); Beigzadeh, Reza [Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Rahimi, Masoud [Razi University, Kermanshah (Iran, Islamic Republic of)

    2013-09-15

    A feed forward three-layer artificial neural network (ANN) model was developed for VLE prediction of ternary systems including ionic liquid (IL) (water+ethanol+1-butyl-3- methyl-imidazolium acetate), in a relatively wide range of IL mass fractions up to 0.8, with the mole fractions of ethanol on IL-free basis fixed separately at 0.1, 0.2, 0.4, 0.6, 0.8, and 0.98. The output results of the ANN were the mole fraction of ethanol in vapor phase and the equilibrium temperature. The validity of the model was evaluated through a test data set, which were not employed in the training case of the network. The performance of the ANN model for estimating the mole fraction and temperature in the ternary system including IL was compared with the non-random-two-liquid (NRTL) and electrolyte non-random-two- liquid (eNRTL) models. The results of this comparison show that the ANN model has a superior performance in predicting the VLE of ternary systems including ionic liquid.

  12. Strong flexoelectric behavior in bimesogenic liquid crystals

    Science.gov (United States)

    Coles, H. J.; Clarke, M. J.; Morris, S. M.; Broughton, B. J.; Blatch, A. E.

    2006-02-01

    In this paper, we demonstrate strong flexoelectric coupling in bimesogenic liquid crystals. This strong coupling is determined via the flexoelectro-optic effect in chiral nematic liquid crystals based on bimesogenic mixtures that are doped with low concentrations of high twisting power chiral additive. Two mixtures were examined: one had a pitch length of p~300 nm, the other had a pitch length of p~600 nm. These mixtures exhibit enantiotropic chiral nematic phases close to room temperature. We found that full-intensity modulation, that is, a rotation of the optic axis of 45° between crossed polarizers, could be achieved at significantly lower applied electric fields (E<5 V μm-1) than previously reported. In fact, for the condition of full-intensity modulation, the lowest electric-field strength recorded was E=2 V μm-1. As a result of a combination of the strong flexoelectric coupling and a divergence in the pitch, tilt angles of the optic axis up to 87°, i.e., a rotation of the optic axis through 174°, were observed. Furthermore, the flexoelastic ratios, which may be considered as a figure-of-merit parameter, were calculated from the results and found to be large, ranging from 1.3 to 2 C/Nm for a temperature range of up to 40 °C.

  13. Beam steering by liquid crystal elastomer fibres.

    Science.gov (United States)

    Nocentini, S; Martella, D; Wiersma, D S; Parmeggiani, C

    2017-11-22

    The problem of utilizing a laser beam as an information vehicle and dividing it into different channels is an open problem in the telecommunication field. The switching of a signal into different ports has been demonstrated, to date, by employing complex devices and mechanisms such as the electro optic effect, microelectromechanical system (MEMS) mirrors, or liquid crystal-based spatial light modulators (SLMs). We present here a simple device, namely a mirror held by a liquid crystal elastomer (LCE) fibre, as an optically and remotely driven beam steerer. In fact, a considered signal (laser beam) can be addressed in every in-plane direction by controlling the fibre and mirror rotation, i.e., the deflected probe beam angle. Such movement is possible due to the preparation of LCE fibres able to rotate and contract under a selective light stimulus. By adjusting the irradiation stimulus power, elastic fibres are able to rotate with a specific angle, performing more than one complete revolution around their axis. The described movement is perfectly reversible as soon as the stimulus is removed.

  14. Multistability in planar liquid crystal wells

    KAUST Repository

    Luo, Chong

    2012-06-08

    A planar bistable liquid crystal device, reported in Tsakonas, is modeled within the Landau-de Gennes theory for nematic liquid crystals. This planar device consists of an array of square micrometer-sized wells. We obtain six different classes of equilibrium profiles and these profiles are classified as diagonal or rotated solutions. In the strong anchoring case, we propose a Dirichlet boundary condition that mimics the experimentally imposed tangent boundary conditions. In the weak anchoring case, we present a suitable surface energy and study the multiplicity of solutions as a function of the anchoring strength. We find that diagonal solutions exist for all values of the anchoring strength W≥0, while rotated solutions only exist for W≥W c>0, where W c is a critical anchoring strength that has been computed numerically. We propose a dynamic model for the switching mechanisms based on only dielectric effects. For sufficiently strong external electric fields, we numerically demonstrate diagonal-to-rotated and rotated-to-diagonal switching by allowing for variable anchoring strength across the domain boundary. © 2012 American Physical Society.

  15. Electrically Tuned Microwave Devices Using Liquid Crystal Technology

    Directory of Open Access Journals (Sweden)

    Pouria Yaghmaee

    2013-01-01

    Full Text Available An overview of liquid crystal technology for microwave and millimeter-wave frequencies is presented. The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies. This paper describes physical theory and fundamental electrical properties arising from the anisotropy of liquid crystals and overviews selected realized liquid crystal devices, throughout four main categories: resonators and filters, phase shifters and delay lines, antennas, and, finally, frequency-selective surfaces and metamaterials.

  16. Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

    OpenAIRE

    Shanks, Robert A.; Daniel Staszczyk

    2012-01-01

    Liquid crystals are compounds that display order in the liquid state above the melting temperature and below the mesogenic isotropic temperature. Polymer-dispersed liquid crystals (PDLCs) are composite materials in which liquid crystalline material is dispersed within a polymer matrix to form micron-sized droplets. The aim was to prepare several cholesteryl esters or alkoxybenzoic acid PDLCs and characterise thermal and optical properties. Differential scanning calorimetry and polarized optic...

  17. Phase relations and crystal structures in the ternary systems Sr-{Ag, Au}-{Si, Ge}

    Energy Technology Data Exchange (ETDEWEB)

    Zeiringer, Isolde [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, 1090 Vienna (Austria); Grytsiv, Andriy [Christian Doppler Laboratory for Thermoelectric Research, Vienna (Austria); Bauer, Ernst [Christian Doppler Laboratory for Thermoelectric Research, Vienna (Austria); Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna (Austria); Giester, Gerald [Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse14, 1090 Vienna (Austria); Rogl, Peter [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, 1090 Vienna (Austria); Christian Doppler Laboratory for Thermoelectric Research, Vienna (Austria)

    2015-07-15

    Phase equilibria in the isothermal sections of the ternary systems Sr-{Ag, Au}-{Si, Ge} were determined in the (Si) or (Ge) rich part up to 33.3 at % Sr after annealing at 700 C (Sr-{Ag, Au}-Ge) or 800 C (Sr-{Ag, Au}-Si). Tentative liquidus projections were constructed for the Si, Ge-rich part of all the four phase diagrams. These systems are characterized by a series of ternary compounds, exhibiting in some cases extended homogeneity regions at a constant Sr content. Compounds in the Si, Ge-rich region essentially form along two sections: at 33.3 at % Sr (AlB{sub 2}-family) and at 20 at % Sr (BaAl{sub 4}-family of structure types). The crystal structures of the novel equilibrium phases were derived by X-ray single crystal diffraction: Sr{sub 2}Ag{sub 1+x}Si{sub 3-x-y}□{sub y} [Sr{sub 2}LiSi{sub 3} type; x = 0.17, y = 0.43: a = 8.4488(2), b = 14.6376(2), c = 18.4018(2) Aa], SrAg{sub 2-x}Si{sub 2+x} [ThCr{sub 2}Si{sub 2} type; x = 0.1: a = 4.37664(6), c = 10.4517(2) Aa], Sr(Au{sub 1-y}□{sub y})(Si{sub 1-x}Au{sub x}){sub 3} [BaNiSn{sub 3} type; x = 0.59, y = 0.64: a = 4.4594(2), c = 10.1013(6) Aa] and SrAu{sub 5-x}□{sub x}Si{sub 2} [BaAu{sub 5}Si{sub 2} type; x = 0.7: a = 8.7557(3), b = 6.9945(2), c = 9.8873(3) Aa]. The crystal structures of Sr(Ag{sub x}Ge{sub 1-x}){sub 2} [AlB{sub 2} type; x = 0.25: a = 4.3431(2), c = 4.5938(1) Aa], SrAg{sub 2-x}Ge{sub 2+x} [ThCr{sub 2}Si{sub 2} type; x = 0.2: a = 4.4476(2), c = 10.822(1) Aa] and Sr(Au{sub x}Ge{sub 1-x}){sub 2} [AlB{sub 2} type; x = 0.25: a = 4.3263(2), c = 4.5852(7) Aa] were evaluated by X-ray powder Rietveld analysis. Composition dependent polymorphism was observed among the BaAl{sub 4}-type derivative structures for SrAu{sub 2-x}Ge{sub 2+x}: CaBe{sub 2}Ge{sub 2} type [x = 0.45: a = 4.4796(2), c = 10.6315(5) Aa], BaCu{sub 2}Sb{sub 2} type [x = 0.35: a = 4.4866(2), c = 31.808(1) Aa] and ThCr{sub 2}Si{sub 2} type [x = 0.2: a = 4.5214(4), c = 10.336(1) Aa]. Similarly, Sr(Au{sub x}Si{sub 1-x}){sub 2} exhibits

  18. Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic disp...

  19. Alignment technology and applications of liquid crystal devices

    CERN Document Server

    Takatoh, Kohki; Hasegawa, Ray; Koden, Mitsushiro; Itoh, Nobuyuki; Hasegawa, Masaki

    2005-01-01

    Alignment phenomena are characteristic of liquid crystalline materials, and understanding them is critically important in understanding the essential features and behavior of liquid crystals and the performance of Liquid Crystal Devices (LCDs). Furthermore, in LCD production lines, the alignment process is of practical importance. Alignment Technologies and Applications of Liquid Crystal Devices demonstrates both the fundamental and practical aspects of alignment phenomena in liquid crystals. The physical basis of alignment phenomena is first introduced in order to aid the understanding of the various physical phenomena observed in the interface between liquid crystalline materials and alignment layer surfaces. Methods for the characterization of surfaces, which induce the alignment phenomena, and of the alignment layer itself are introduced. These methods are useful for the research of liquid crystalline materials and devices in academic research as well as in industry. In the practical sections, the alignme...

  20. Tunable liquid crystal multifocal microlens array.

    Science.gov (United States)

    Algorri, José Francisco; Bennis, Noureddine; Urruchi, Virginia; Morawiak, Przemek; Sánchez-Pena, José Manuel; Jaroszewicz, Leszek R

    2017-12-11

    A novel liquid crystal microlens array with tunable multifocal capability, high optical power and fill-factor is proposed and experimentally demonstrated. A specific hole pattern design produces a multifocal array with only one voltage control. Three operations modes are possible, "Off", "Tunable Multifocal" and "Unifocal". The design is patterned in both substrates. Then, the substrates are arranged in symmetrical configuration. The result is a high optical power in comparison with typical hole patterned structures. Besides, it is proposed a hexagonal pattern that produces a high fill factor, specially indicated for some applications as Integral Imaging. The array has several useful characteristics for this type of application: tunability for the loss of resolution; multifocal for extended DOF; high fill factor for increase the number of views; and low power consumption for integration in portable devices. Moreover, the optical characteristics of the proposed device could bring new applications in other fields.

  1. Lipid decorated liquid crystal pressure sensors

    Science.gov (United States)

    Lopatkina, Tetiana; Popov, Piotr; Honaker, Lawrence; Jakli, Antal; Mann, Elizabeth; Mann's Group Collaboration; Jakli's Group Collaboration

    Surfactants usually promote the alignment of liquid crystal (LC) director parallel to the surfactant chains, and thus on average normal to the substrate (homeotropic), whereas water promotes tangential (planar) alignment. A water-LC interface is therefore very sensitive to the presence of surfactants, such as lipids: this is the principle of LC-based chemical and biological sensing introduced by Abbott et al.Using a modified configuration, we found that at higher than 10 micro molar lipid concentration, the uniformly dark texture seen for homeotropic alignment between left-, and right-handed circular polarizers becomes unstable and slowly brightens again. This texture shows extreme sensitivity to external air pressure variations offering its use for sensitive pressure sensors. Our analysis indicates an osmotic pressure induced bending of the suspended films explaining both the birefringence and pressure sensitivity. In the talk we will discuss the experimental details of these effects. This work was financially supported by NSF DMR No. DMR-0907055.

  2. Highly anisotropic conductivity in organosiloxane liquid crystals

    Science.gov (United States)

    Gardiner, D. J.; Coles, H. J.

    2006-12-01

    In this paper, we present the conductivity and dielectric characterization of three homologous series of smectic A siloxane containing liquid crystals. The materials studied include one monomesogenic series, which consists of a 4-(ω-alkyloxy)-4'-cyanobiphenyl unit terminated by pentamethyldisiloxane, and two bimesogenic series, which consist of twin 4-(ω-alkyloxy)-4'-cyanobiphenyls joined via tetramethyldisiloxane or decamethylpentasiloxane. All of the compounds exhibit wide temperature range enantiotropic smectic A phases; the effect of the siloxane moiety is to suppress nematic morphology even in the short chain homologs. We find that these compounds exhibit a highly anisotropic conductivity: the value perpendicular to the director is to up to 200 times that parallel to the director. For the nonsiloxane analog 4-(ω-octyl)-4'-cyanobiphenyl (8CB), this value is approximately 2. It is also found that the dielectric anisotropy is reduced significantly; a typical value is ˜1 compared to 8.4 for 8CB. We propose that the origin of these unusual properties is in the smectic structure; the microphase separation of the bulky, globular siloxane moieties into liquidlike regions severely inhibits the mobility parallel to the director and across the smectic layers. Further, the inclusion of this unit acts to increase the antiparallel correlations of molecular dipoles in the aromatic and alkyloxy sublayers, reducing the dielectric anisotropy significantly compared to nonsiloxane analogs. The highly anisotropic conductivity suggests that these materials are particularly suitable for application in electro-optic effects which exploit this property, e.g., the bistable electro-optic effect in smectic A liquid crystals.

  3. Microwave modulation characteristics of twisted liquid crystals with chiral dopant

    Directory of Open Access Journals (Sweden)

    Rui Yuan

    2017-01-01

    Full Text Available Adding a chiral dopant in twisted nematic (TN liquid crystal cell can stabilize the orientation of liquid crystal molecules, particularly in high TN (HTN or super TN (STN liquid crystal cells. The difference in pitches in liquid crystal is induced by the chiral dopant, and these different pitches affect the orientation of liquid crystal director under an external applied voltage and influence the characteristics of microwave modulation. To illustrate this point, the microwave phase shift per unit length (MPSL versus voltage is calculated on the basis of the elastic theory of liquid crystal and the finite-difference iterative method. Enhancing the pitch induced by the chiral dopant in liquid crystal increases the MPSLs, but the stability of the twisted structures is decreased. Thus, appropriate pitches of 100d, 4d, and 2d can be applied in TN, HTN, and STN cells with cell gap d to enhance the characteristics of microwave modulation and stabilize the structures in twisted cell. This method can improve the characteristics of liquid crystal microwave modulators such that the operating voltage and the size of such phase shifters can be decreased.

  4. Synthesis and Physical Properties of Liquid Crystals: An Interdisciplinary Experiment

    Science.gov (United States)

    Van Hecke, Gerald R.; Karukstis, Kerry K.; Hanhan Li; Hendargo, Hansford C.; Cosand, Andrew J.; Fox, Marja M.

    2005-01-01

    A study involves multiple chemistry and physics concepts applied to a state of matter that has biological relevance. An experiment involving the synthesis and physical properties of liquid crystals illustrates the interdisciplinary nature of liquid crystal research and the practical devices derived from such research.

  5. Liquid-crystal intraocular adaptive lens with wireless control

    NARCIS (Netherlands)

    Simonov, A.N.; Vdovine, G.V.; Loktev, M.

    2007-01-01

    We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low- and high-ohmic electrodes, respectively.

  6. Electrochromic blueshift in polymer-dispersed liquid-crystal cells.

    Science.gov (United States)

    Ramsey, R A; Sharma, S C

    2004-10-01

    Electrochromic blueshift in the absorption band of polymer-dispersed liquid-crystal cells is reported as a function of applied electric field. The changes in the peak absorption wavelength, absorption broadening, and their possible relationships with the nonlinear optical properties of polymer-dispersed liquid-crystal cells are discussed.

  7. Quantum Liquid Crystal Phases in Strongly Correlated Fermionic Systems

    Science.gov (United States)

    Sun, Kai

    2009-01-01

    This thesis is devoted to the investigation of the quantum liquid crystal phases in strongly correlated electronic systems. Such phases are characterized by their partially broken spatial symmetries and are observed in various strongly correlated systems as being summarized in Chapter 1. Although quantum liquid crystal phases often involve…

  8. Orientation control of dye molecules in a liquid crystal.

    Science.gov (United States)

    Urisu, T; Kajiyama, K; Mizushima, Y

    1978-08-01

    Laser dye molecules (coumarin 6) were dissolved in a nematic liquid crystal MBBA + BBCA. Great changes in polarization and fluorescence vs applied voltage were found as well as a change in dielectric constant. Molecular orientation of the liquid crystal under the electric field and association of the dye molecules are identified as having the greatest effect on the fluorescence intensity.

  9. Graphene-based liquid crystal microlens arrays

    Science.gov (United States)

    Hu, Wei; Chen, Cheng; Wu, Yong; Luo, Jun; Lei, Yu; Tong, Qing; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-12-01

    In this paper, we design and fabricate a kind of liquid crystal microlens arrays (LCMAs) with patterned electrodes made of monolayer graphene, which is grown on copper sheet by chemical vapor deposition (CVD). Graphene is the first two-dimensional atomic crystal. It uniquely combines extreme mechanical strength, high optically transmittance from visible light to infrared spectrum, and excellent electrical conductivity. These properties make it highly attractive for various applications in photonic devices that require conductive but transparent thin films. The graphene-based LCMAs have shown excellent optical performances in the tests. By adjusting the voltage signal loaded over the graphene-based LCMAs, the point spread functions (PSF) and focusing images of incident laser beams with different wavelengths, could be obtained. At the same time, we also get the focusing images of the common ITO-based LCMAs under the same experimental conditions to discuss the advantages and disadvantages between them. Further, the graphene-based LCMAs are also used in visible imaging. During the imaging tests, the graphene electrodes in the LCMAs work well.

  10. LIQUID-LIQUID EQUILIBRIA OF THE TERNARY SYSTEMS PROPIONIC ACID - WATER - SOLVENT (n-AMYL ALCOHOL AND n-AMYL ACETATE

    Directory of Open Access Journals (Sweden)

    Dilek ÖZMEN

    2005-02-01

    Full Text Available The experimental liquid-liquid equilibrium (LLE data have been obtained at 25 oC for ternary systems propionic acid-water-n-amyl alcohol and propionic acid-water-n-amyl acetate. The reliability of the experimental tie line data are checked using the methods of Othmer-Tobias and Hand. The distribution coefficients and separation factors were obtained from experimental results and are also reported. The predicted tie line data obtained by UNIFAC method are compared with experimental data. It is concluded that n-amyl alcohol and n-amyl acetate are suitable separating agents for dilute aqueous propionic acid solutions.

  11. LIQUID-LIQUID EQUILIBRIA OF THE TERNARY SYSTEMS PROPIONIC ACID - WATER - SOLVENT (n-AMYL ALCOHOL AND n-AMYL ACETATE)

    OpenAIRE

    Dilek ÖZMEN

    2005-01-01

    The experimental liquid-liquid equilibrium (LLE) data have been obtained at 25 oC for ternary systems propionic acid-water-n-amyl alcohol and propionic acid-water-n-amyl acetate. The reliability of the experimental tie line data are checked using the methods of Othmer-Tobias and Hand. The distribution coefficients and separation factors were obtained from experimental results and are also reported. The predicted tie line data obtained by UNIFAC method are compared with experimental data. It i...

  12. Plasmonic Photopatterning of Complex Molecular Orientations in Liquid Crystals

    Science.gov (United States)

    Guo, Yubing; Jiang, Miao; Peng, Chenhui; Sun, Kai; Yaroshchuk, Oleg; Lavrentovich, Oleg; Wei, Qi-Huo

    Aligning liquid crystal (LC) molecules in spatially non-uniform patterns are highly demanded for applications such as programmable origami and liquid crystal enabled nonlinear electrokinetics. We developed a high resolution projection photoalignment technique for patterning arbitrary LC alignment fields. The photoalignment is based on carefully engineered metasurfaces, or dubbed as plasmonic metamasks (PMMs). When illuminated by light, the PMMs generate patterns of both light intensity and polarization. By projecting the light transmitted through the PMMs onto liquid crystal cells coated with photosensitive materials, alignment patterns predesigned in polarization patterns of the PMMs can be imposed in liquid crystals. This technique makes the liquid crystal alignment a repeatable and scalable process similar to conventional photolithography, promising various applications. National Science Foundation CMMI-1436565.

  13. Graphene chiral liquid crystals and macroscopic assembled fibres

    Science.gov (United States)

    Xu, Zhen; Gao, Chao

    2011-12-01

    Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles.

  14. Simulation of liquid crystals. Disclinations and surface modification

    CERN Document Server

    Downton, M

    2001-01-01

    In this thesis we investigate the behaviour of molecular models liquid crystals in several different situations. Basic introductory material on liquid crystals and computer simulations is discussed in the first two chapters, we then discuss the research. The third chapter investigates the interaction between a liquid crystal and a modified surface. A confined system of hard spherocylinders in a slab geometry is examined. The surface consists of planar hard walls with elongated molecules grafted perpendicularly onto them. The concentration of grafted molecules is varied to give different surfaces. Several different behaviours are found including planar, homeotropic and tilted anchorings of the liquid crystal. Molecular dynamics simulations of a nematic liquid crystal in slab geometry with twisted boundary conditions are performed. By arranging the initial configuration suitably it is possible to create a simulation cell with two regions of opposite twist separated by a strength half disclination line. The prop...

  15. Insertion of liquid crystal molecules into hydrocarbon monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Popov, Piotr, E-mail: ppopov@kent.edu; Mann, Elizabeth K. [Department of Physics, Kent State University, Kent, Ohio 44242 (United States); Lacks, Daniel J. [Department of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Jákli, Antal [Liquid Crystal Institute, Kent State University, Kent, Ohio 44242-0001 (United States)

    2014-08-07

    Atomistic molecular dynamics simulations were carried out to investigate the molecular mechanisms of vertical surface alignment of liquid crystals. We study the insertion of nCB (4-Cyano-4{sup ′}-n-biphenyl) molecules with n = 0,…,6 into a bent-core liquid crystal monolayer that was recently found to provide good vertical alignment for liquid crystals. The results suggest a complex-free energy landscape for the liquid crystal within the layer. The preferred insertion direction of the nCB molecules (core or tail first) varies with n, which can be explained by entropic considerations. The role of the dipole moments was found to be negligible. As vertical alignment is the leading form of present day liquid crystal displays (LCD), these results will help guide improvement of the LCD technology, as well as lend insight into the more general problem of insertion of biological and other molecules into lipid and surfactant layers.

  16. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R

    2013-01-01

    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  17. Dynamic Photonic Materials Based on Liquid Crystals (Postprint)

    Science.gov (United States)

    2013-09-01

    in liquid-crystalline side chain polymers. Liquid Crystals, 33, 1421–1427. Atkins , P.W. (1987). Physical chemistry . Oxford: Oxford University Press...Journal of Physical Chemistry C, 114, 7496–7501. Kogelnik,H. (1969). Coupled wave theory for thick hologram gratings. Bell SystemTechnical Journal, 48... Physical Chemistry B, 103, 4212–4217. Lu, S.-Y. & Chien, L.-C. (2007). A polymer-stabilized single-layer color cholesteric liquid crystal display with

  18. H-Bond stabilized columnar discotic liquid crystals

    NARCIS (Netherlands)

    Paraschiv, I.

    2007-01-01

    Since 1977, more than 2300 publications on discotic (disk-like) liquid crystalline materials have appeared. Discotic liquid crystals, which usually consist of polyaromatic molecules surrounded by long peripheral alkyl tails, can form liquid crystalline mesophases in a wide temperature range. Within

  19. Partially crystalline systems in lyophilization: I. Use of ternary state diagrams to determine extent of crystallization of bulking agent.

    Science.gov (United States)

    Chatterjee, Koustuv; Shalaev, Evgenyi Y; Suryanarayanan, Raj

    2005-04-01

    Two model ternary systems: water-glycine-raffinose and water-glycine-trehalose were investigated to determine the extent of glycine crystallization in frozen solutions. The use of such partially crystalline systems allows primary drying to be carried out substantially above the collapse temperature. Differential scanning calorimetry (DSC) and variable temperature X-ray diffractometry (XRD) were used to monitor phase transitions in frozen systems as well as to determine the T'g. Aqueous solutions containing different glycine to carbohydrate weight ratios were first cooled to -60 degrees C and then warmed to room temperature. In both raffinose and trehalose systems, when the initial glycine to sugar (raffinose pentahydrate or trehalose dihydrate) ratio was or=1, partial glycine crystallization was observed during warming. The presence of amorphous glycine caused the T'g to be substantially lower than that of the solution containing only the carbohydrate. To determine the extent of glycine crystallization, the solutions were annealed for 5 h just above the temperature of glycine crystallization. The T'g observed in the second warming curve was very close to that of the carbohydrate solution alone, indicating almost complete glycine crystallization. These studies enabled the construction of the water-rich sections of the raffinose-glycine-water and trehalose-glycine-water state diagrams. These diagrams consist of a kinetically stable freeze-concentrated solution and a doubly unstable glassy region, which readily crystallizes during cooling or subsequent warming. In addition, there is an intermediate region, where during the experimental timescale, there appears to be hindered glycine nucleation but unhindered crystal growth. To obtain substantially crystalline glycine in the frozen solutions, the glycine to carbohydrate ratios should be >or=1. Copyright (c) 2005 Wiley-Liss, Inc.

  20. Crystal-liquid-gas phase transitions and thermodynamic similarity

    CERN Document Server

    Skripov, Vladimir P; Schmelzer, Jurn W P

    2006-01-01

    Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

  1. Liquid crystals in micron-scale droplets, shells and fibers

    Science.gov (United States)

    Urbanski, Martin; Reyes, Catherine G.; Noh, JungHyun; Sharma, Anshul; Geng, Yong; Subba Rao Jampani, Venkata; Lagerwall, Jan P. F.

    2017-04-01

    The extraordinary responsiveness and large diversity of self-assembled structures of liquid crystals are well documented and they have been extensively used in devices like displays. For long, this application route strongly influenced academic research, which frequently focused on the performance of liquid crystals in display-like geometries, typically between flat, rigid substrates of glass or similar solids. Today a new trend is clearly visible, where liquid crystals confined within curved, often soft and flexible, interfaces are in focus. Innovation in microfluidic technology has opened for high-throughput production of liquid crystal droplets or shells with exquisite monodispersity, and modern characterization methods allow detailed analysis of complex director arrangements. The introduction of electrospinning in liquid crystal research has enabled encapsulation in optically transparent polymeric cylinders with very small radius, allowing studies of confinement effects that were not easily accessible before. It also opened the prospect of functionalizing textile fibers with liquid crystals in the core, triggering activities that target wearable devices with true textile form factor for seamless integration in clothing. Together, these developments have brought issues center stage that might previously have been considered esoteric, like the interaction of topological defects on spherical surfaces, saddle-splay curvature-induced spontaneous chiral symmetry breaking, or the non-trivial shape changes of curved liquid crystal elastomers with non-uniform director fields that undergo a phase transition to an isotropic state. The new research thrusts are motivated equally by the intriguing soft matter physics showcased by liquid crystals in these unconventional geometries, and by the many novel application opportunities that arise when we can reproducibly manufacture these systems on a commercial scale. This review attempts to summarize the current understanding of

  2. Liquid crystals beyond displays chemistry, physics, and applications

    CERN Document Server

    Li, Quan

    2012-01-01

    The chemistry, physics, and applications of liquid crystals beyond LCDs Liquid Crystals (LCs) combine order and mobility on a molecular and supramolecular level. But while these remarkable states of matter are most commonly associated with visual display technologies, they have important applications for a variety of other fields as well. Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications considers these, bringing together cutting-edge research from some of the most promising areas of LC science. Featuring contributions from respected researchers from around the globe, th

  3. Structural Transitions in Cholesteric Liquid Crystal Droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye; Bukusoglu, Emre; Martínez-González, José A.; Rahimi, Mohammad; Roberts, Tyler F.; Zhang, Rui; Wang, Xiaoguang; Abbott, Nicholas L.; de Pablo, Juan J.

    2016-07-26

    Confinement of cholesteric liquid crystals (ChLC) into droplets leads to a delicate interplay between elasticity, chirality, and surface energy. In this work, we rely on a combination of theory and experiments to understand the rich morphological behavior that arises from that balance. More specifically, a systematic study of micrometer-sized ChLC droplets is presented as a function of chirality and surface energy (or anchoring). With increasing chirality, a continuous transition is observed from a twisted bipolar structure to a radial spherical structure, all within a narrow range of chirality. During such a transition, a bent structure is predicted by simulations and confirmed by experimental observations. Simulations are also able to capture the dynamics of the quenching process observed in experiments. Consistent with published work, it is found that nanoparticles are attracted to defect regions on the surface of the droplets. For weak anchoring conditions at the nanoparticle surface, ChLC droplets adopt a morphology similar to that of the equilibrium helical phase observed for ChLCs in the bulk. As the anchoring strength increases, a planar bipolar structure arises, followed by a morphological transition to a bent structure. The influence of chirality and surface interactions are discussed in the context of the potential use of ChLC droplets as stimuli-responsive materials for reporting molecular adsorbates.

  4. Artificial muscles based on liquid crystal elastomers.

    Science.gov (United States)

    Li, Min-Hui; Keller, Patrick

    2006-10-15

    This paper presents our results on liquid crystal (LC) elastomers as artificial muscle, based on the ideas proposed by de Gennes. In the theoretical model, the material consists of a repeated series of main-chain nematic LC polymer blocks, N, and conventional rubber blocks, R, based on the lamellar phase of a triblock copolymer RNR. The motor for the contraction is the reversible macromolecular shape change of the chain, from stretched to spherical, that occurs at the nematic-to-isotropic phase transition in the main-chain nematic LC polymers. We first developed a new kind of muscle-like material based on a network of side-on nematic LC homopolymers. Side-on LC polymers were used instead of main-chain LC polymers for synthetic reasons. The first example of these materials was thermo-responsive, with a typical contraction of around 35-45% and a generated force of around 210 kPa. Subsequently, a photo-responsive material was developed, with a fast photochemically induced contraction of around 20%, triggered by UV light. We then succeeded in preparing a thermo-responsive artificial muscle, RNR, with lamellar structure, using a side-on nematic LC polymer as N block.Micrometre-sized artificial muscles were also prepared. This paper illustrates the bottom-up design of stimuli-responsive materials, in which the overall material response reflects the individual macromolecular response, using LC polymer as building block.

  5. Lenticular arrays based on liquid crystals

    Science.gov (United States)

    Urruchi Del Pozo, V.; Algorri Genaro, J. F.; Sánchez-Pena, J. M.; Geday, M. A.; Arregui, X. Q.; Bennis, N.

    2012-09-01

    Lenticular array products have experienced a growing interest in the last decade due to the very wide range of applications they can cover. Indeed, this kind of lenses can create different effects on a viewing image such as 3D, flips, zoom, etc. In this sense, lenticular based on liquid crystals (LC) technology is being developed with the aim of tuning the lens profiles simply by controlling the birefringence electrically. In this work, a LC lenticular lens array has been proposed to mimic a GRIN lenticular lens array but adding the capability of tuning their lens profiles. Comb control electrodes have been designed as pattern masks for the ITO on the upper substrate. Suitable high resistivity layers have been chosen to be deposited on the control electrode generating an electric field gradient between teeth of the same electrode. Test measurements have allowed us to demonstrate that values of phase retardations and focal lengths, for an optimal driving waveform, are fairly in agreement. In addition, results of focusing power of tuneable lenses were compared to those of conventional lenses. The behaviour of both kinds of lenses has revealed to be mutually similar for focusing collimated light and for refracting images.

  6. The research on temperature sensing properties of photonic crystal fiber based on Liquid crystal filling

    Directory of Open Access Journals (Sweden)

    Zan Xiangzhen

    2016-01-01

    Full Text Available Based on the photonic bandgap-photonic crystal fibers( PBG-PCF fiber core fills the namitic liquid crystal. By readjusting the temperature to change the refractive index, constitute new liquid fiber-optic temperature sensor. In this paper, we use finite element COMSOL software to simulate and analyze photonic crystal optical fiber sensitive properties. The research show that after the PBG – PCF filling the liquid crystal, its mode field distribution, effective refractive index, waveguide dispersion etc changing with temperature is so big. Therefore, the properties that the refractive index of PCF mode CF changing with temperature sensitive medium, provides the theoretical basis for designing optic fiber temperature sensors.

  7. Holographic Polymer-Dispersed Liquid Crystals: Materials, Formation, and Applications

    Directory of Open Access Journals (Sweden)

    Y. J. Liu

    2008-01-01

    Full Text Available By combining polymer-dispersed liquid crystal (PDLC and holography, holographic PDLC (H-PDLC has emerged as a new composite material for switchable or tunable optical devices. Generally, H-PDLC structures are created in a liquid crystal cell filled with polymer-dispersed liquid crystal materials by recording the interference pattern generated by two or more coherent laser beams which is a fast and single-step fabrication. With a relatively ideal phase separation between liquid crystals and polymers, periodic refractive index profile is formed in the cell and thus light can be diffracted. Under a suitable electric field, the light diffraction behavior disappears due to the index matching between liquid crystals and polymers. H-PDLCs show a fast switching time due to the small size of the liquid crystal droplets. So far, H-PDLCs have been applied in many promising applications in photonics, such as flat panel displays, switchable gratings, switchable lasers, switchable microlenses, and switchable photonic crystals. In this paper, we review the current state-of-the-art of H-PDLCs including the materials used to date, the grating formation dynamics and simulations, the optimization of electro-optical properties, the photonic applications, and the issues existed in H-PDLCs.

  8. NATO Advanced Research Workshop on Incommensurate Crystals, Liquid Crystals, and Quasi-Crystals

    CERN Document Server

    Clark, N

    1988-01-01

    In this NATO-sponsored Advanced Research Workshop we succeeded in bringing together approximately forty scientists working in the three main areas of structurally incommensurate materials: incommensurate crystals (primarily ferroelectric insulators), incommensurate liquid crystals, and metallic quasi-crystals. Although these three classes of materials are quite distinct, the commonality of the physics of the origin and descrip­ tion of these incommensurate structures is striking and evident in these proceedings. A measure of the success of this conference was the degree to which interaction among the three subgroups occurred; this was facili­ tated by approximately equal amounts of theory and experiment in the papers presented. We thank the University of Colorado for providing pleasant housing and conference facilities at a modest cost, and we are especially grate­ ful to Ann Underwood, who retyped all the manuscripts into camera-ready form. J. F. Scott Boulder, Colorado N. A. Clark v CONTENTS PART I: INCO...

  9. Mechanism of the emergence of the photo-EMF upon silicon liquid crystal-single crystal contact

    Science.gov (United States)

    Budagov, K. M.; Guseinov, A. G.; Pashaev, B. G.

    2017-03-01

    The effect light has on a silicon liquid crystal-single crystal contact at different temperatures of the surface doping of silicon, and when BaTiO3 nanoparticles are added to the composition of a liquid crystal, is studied. The mechanism of the emergence of the photo-EMF in the liquid crystal-silicon structure is explained.

  10. Effect of binder liquid type on spherical crystallization.

    Science.gov (United States)

    Maghsoodi, Maryam; Hajipour, Ali

    2014-11-01

    Spherical crystallization is a process of formation of agglomerates of crystals held together by binder liquid. This research focused on understanding the effect of type of solvents used as binder liquid on the agglomeration of crystals. Carbamazepine and ethanol/water were used respectively as a model drug and crystallization system. Eight solvents as binder liquid including chloroform, dichloromethane, isopropyl acetate, ethyl acetate, n-hexane, dimethyl aniline, benzene and toluene were examined to better understand the relationship between the physical properties of the binder liquid and its ability to bring about the formation of the agglomerates. Moreover, the agglomerates obtained from effective solvents as binder liquid were evaluated in term of size, apparent particle density and compressive strength. In this study the clear trend was observed experimentally in the agglomerate formation as a function of physical properties of the binder liquid such as miscibility with crystallization system. Furthermore, the properties of obtained agglomerates such as size, apparent particle density and compressive strength were directly related to physical properties of effective binder liquids. RESULTS of this study offer a useful starting point for a conceptual framework to guide the selection of solvent systems for spherical crystallization.

  11. Controllable light diffraction in woodpile photonic crystals filled with liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Chih-Hua; Zeng, Hao; Wiersma, Diederik S. [European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Cheng, Yu-Chieh; Maigyte, Lina; Trull, Jose; Cojocaru, Crina [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom 11, 08222 Terrassa (Spain); Staliunas, Kestutis [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom 11, 08222 Terrassa (Spain); Institucio Catalana de Reserca i Estudis Avançats (ICREA), passeig Lluis Companys 23, 08010 Barcelona (Spain)

    2015-01-12

    An approach to switching between different patterns of light beams transmitted through the woodpile photonic crystals filled with liquid crystals is proposed. The phase transition between the nematic and isotropic liquid crystal states leads to an observable variation of the spatial pattern transmitted through the photonic structure. The transmission profiles in the nematic phase also show polarization sensibility due to refractive index dependence on the field polarization. The experimental results are consistent with a numerical calculation by Finite Difference Time Domain method.

  12. Electrically tunable bandpass filter using solid-core photonic crystal fibers filled with multiple liquid crystals

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2010-01-01

    An electrically tunable bandpass filter is designed and fabricated by integrating two solid-core photonic crystal fibers filled with different liquid crystals in a double silicon v-groove assembly. By separately controlling the driving voltage of each liquid-crystal-filled section, both the short......-wavelength edge and the long-wavelength edge of the bandpass filter are tuned individually or simultaneously with the response time in the millisecond range....

  13. Ternary liquid-liquid equilibria of dimethyl carbonate + 2-propanol + water system at 303.15 and 313.15 K

    Science.gov (United States)

    Ginting, Rizqy Romadhona; Mustain, Asalil; Tetrisyanda, Rizki; Gunardi, Ignatius; Wibawa, Gede

    2015-12-01

    In this work, liquid-liquid equilibria data of dimethyl carbonate (DMC) + 2-propanol + water system were accurately determined at 303.15 and 313.15 K using stirred and jacketed equilibrium cell under atmospheric pressure. The reliabilities of the experimental data were confirmed using Bachman-Brown correlation giving r-squared value of 0.9993 and 0.9983 at 303.15 and 313.15 K, respectively. Experimental data obtained in this work exhibit Treybal's Type I ternary phase behavior. The selectivity and distribution coefficient of DMC increases with addition of DMC concentration in the organic phase. On the other hand, the effect of temperature to phase boundary was found to be not significant. The data were correlated well using the Non-Random Two Liquid (NRTL) and Universal Quasi-Chemical (UNIQUAC) activity coefficient models with root-mean-square deviation of 1.5% and 1.3%, respectively.

  14. Field induced heliconical structure of cholesteric liquid crystal

    Science.gov (United States)

    Lavrentovich, Oleg D.; Shiyanovsii, Sergij V.; Xiang, Jie; Kim, Young-Ki

    2017-06-27

    A diffraction grating comprises a liquid crystal (LC) cell configured to apply an electric field through a cholesteric LC material that induces the cholesteric LC material into a heliconical state with an oblique helicoid director. The applied electric field produces diffracted light from the cholesteric LC material within the visible, infrared or ultraviolet. The axis of the heliconical state is in the plane of the liquid crystal cell or perpendicular to the plane, depending on the application. A color tuning device operates with a similar heliconical state liquid crystal material but with the heliconical director axis oriented perpendicular to the plane of the cell. A power generator varies the strength of the applied electric field to adjust the wavelength of light reflected from the cholesteric liquid crystal material within the visible, infrared or ultraviolet.

  15. Controlling chirality with helix inversion in cholesteric liquid crystals

    NARCIS (Netherlands)

    Katsonis, Nathalie Hélène; Lacaze, E.; Ferrarini, A.

    2012-01-01

    The helical organization of cholesteric liquid crystals is omnipresent in living matter. Achieving control over the structure of the cholesteric helix consequently holds great potential for developing stimuli-responsive materials matching the level of sophistication of biological systems. In

  16. Liquid crystal phase behaviour of colloidal platelets in external fields

    NARCIS (Netherlands)

    Beek, David van der

    2005-01-01

    In this thesis, the liquid crystal phase behaviour of colloidal platelets in external fields is studied. We have specifically investigated the influence of morphological, gravitational, magnetic and centrifugal fields. Part I of this thesis involves sterically stabilised colloidal gibbsite

  17. Phase Change Enthalpies and Entropies of Liquid Crystals

    National Research Council Canada - National Science Library

    Acree, William E; Chickos, James S

    2006-01-01

    .... A group additivity approach used to estimate total phase change entropies of organic molecules applied to 627 of these liquid crystals is found to significantly overestimate their total phase change entropies...

  18. Dynamic self-stiffening in liquid crystal elastomers

    Science.gov (United States)

    Agrawal, Aditya; Chipara, Alin C.; Shamoo, Yousif; Patra, Prabir K.; Carey, Brent J.; Ajayan, Pulickel M.; Chapman, Walter G.; Verduzco, Rafael

    2013-04-01

    Biological tissues have the remarkable ability to remodel and repair in response to disease, injury and mechanical stresses. Synthetic materials lack the complexity of biological tissues, and man-made materials that respond to external stresses through a permanent increase in stiffness are uncommon. Here we report that polydomain nematic liquid crystal elastomers increase in stiffness by up to 90% when subjected to a low-amplitude (5%), repetitive (dynamic) compression. Elastomer stiffening is influenced by liquid crystal content, the presence of a nematic liquid crystal phase and the use of a dynamic as opposed to static deformation. Through rheological and X-ray diffraction measurements, stiffening can be attributed to a mobile nematic director, which rotates in response to dynamic compression. Stiffening under dynamic compression has not been previously observed in liquid crystal elastomers and may be useful for the development of self-healing materials or for the development of biocompatible, adaptive materials for tissue replacement.

  19. Omnidirectional photonic band gap enlarged by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haifeng [College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Nanjing Artillery Academy, Nanjing 211132 (China); Liu Shaobin [College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); State Key Laboratory of Millimeter Waves of Southeast University, Nanjing Jiangsu 210096 (China); Kong Xiangkun; Bian Borui; Dai Yi [College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2012-11-15

    In this paper, an omnidirectional photonic band gap realized by one-dimensional ternary unmagnetized plasma photonic crystals based on a new Fibonacci quasiperiodic structure, which is composed of homogeneous unmagnetized plasma and two kinds of isotropic dielectric, is theoretically studied by the transfer matrix method. It has been shown that such an omnidirectional photonic band gap originates from Bragg gap in contrast to zero-n gap or single negative (negative permittivity or negative permeability) gap, and it is insensitive to the incidence angle and the polarization of electromagnetic wave. From the numerical results, the frequency range and central frequency of omnidirectional photonic band gap can be tuned by the thickness and density of the plasma but cease to change with increasing Fibonacci order. The bandwidth of omnidirectional photonic band gap can be notably enlarged. Moreover, the plasma collision frequency has no effect on the bandwidth of omnidirectional photonic band gap. It is shown that such new structure Fibonacci quasiperiodic one-dimensional ternary plasma photonic crystals have a superior feature in the enhancement of frequency range of omnidirectional photonic band gap compared with the conventional ternary and conventional Fibonacci quasiperiodic ternary plasma photonic crystals.

  20. Isothermal section of the phase diagram and crystal structures of the compounds in the ternary system Tm-Cu-Sb at 870 K

    Science.gov (United States)

    Fedyna, L. O.; Fedorchuk, A. O.; Mykhalichko, V. M.; Shpyrka, Z. M.; Fedyna, M. F.

    2017-07-01

    The isothermal section of the Tm-Cu-Sb phase diagram at 870 K was constructed using X-ray phase analysis. The existence of one ternary compound was confirmed - TmCu1-xGe2 (x = 0.109) (structure type HfCuSi2, space group P4/nmm, Pearson code tP8-0.22, a = 4.24170(2), c = 9.73942(9) Å). New ternary copper antimonides Tm3Cu20+xSb11-x (x = 2) (structure type Dy3Cu20+xSb11-x, space group F-43 m, Pearson code cF272, a = 16.55784(4) Å) and TmCu4-xSb2 (x = 1.065) (structure type ErFe4Ge2 (LTM), space group Pnnm, Pearson code oP14-2.13, a = 7.00565(6), b = 7.83582(6), c = 4.25051(3) Å) were found. The crystal structures of compounds were refined by full-profile Rietveld method using X-ray powder diffraction data. The solubility of the third component in all binary phases was found to be negligible. The crystal structures of known ternary antimonides were analyzed and relationship among the crystal structures of compounds in the ternary system Tm-Cu-Sb was illustrated.

  1. Damping Effect of Lminated Beam Using Liquid Crystal

    OpenAIRE

    谷, 順二; 高木, 敏行; 中庭, 博文; 大友, 規矩雄; 越河, 和男; 藤田, 豊; Junji, TANI; Toshiyuki, TAKAGI; Hirofumi, NAKANIWA; Kikuo, OHTOMO; Kazuo, KOSUGO; Yutaka, FUJITA; 東北大院; 東北大流体研; ロディック(株)

    1996-01-01

    This paper describes an experimental study on the vibration suppression of a laminated beam with a nematic liquid crystal under electric and magnetic fields. Firstly, a laminated beam is constructed of two thin outer aluminum beams with nematic liquid crystal layers and a thin inside aluminum beam. The results under an electric field show that the resonance point of the beam is shifted higher, and the response displacement amplitude decreases as electric field strength increases. This is beca...

  2. Optical detection of sepsis markers using liquid crystal based biosensors

    Science.gov (United States)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  3. Nonlocal gap soliton in liquid infiltrated photonic crystal fibres

    DEFF Research Database (Denmark)

    Bennet, F.H.; Rosberg, C.R.; Rasmussen, Per Dalgaard

    We report on the observation of nonlocal gap solitons in infiltrated photonic crystal fibres. We employ the thermal defocusing nonlinearity of the liquid to study soliton existence and effect of boundaries of the periodic structure.......We report on the observation of nonlocal gap solitons in infiltrated photonic crystal fibres. We employ the thermal defocusing nonlinearity of the liquid to study soliton existence and effect of boundaries of the periodic structure....

  4. Gaussian Filtering with Tapered Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2006-01-01

    We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm......We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm...

  5. Twisting and tweezing liquid crystals with lasers

    Science.gov (United States)

    Gleeson, Helen F.; Dickinson, Mark R.; Sanders, Jennifer E.; Yang, Yiming

    2014-02-01

    Exciting new directions for liquid crystals (LCs) are emerging on the length scale of the wavelength of light. Two complementary micron-sized systems are formed by LC droplets and by dispersions of colloidal particles in LCs. The dimensions of each of these systems are ideal for laser tweezer manipulation, allowing a new range of photon-addressed LC systems to be envisaged. Trapping and moving micron-sized particles in LCs is a beautiful approach that can build novel colloidal photonic materials. However, it is also a unique way of studying fundamental LC properties, particularly anisotropic viscosity coefficients in the low Ericksen regime, which can be accessed by laser trapping. Rather few nematic materials have been studied using laser traps; we describe two different approaches to deduce the viscosity coefficients of nematic mixtures. Micron-sized LC droplets are emerging as intriguing photonic systems in their own right. Angular momentum can be transferred from laser traps to droplets, with specific polarization properties and droplet geometries resulting in a variety of novel photon-driven effects. Fast optical switches, rotating at speeds >1kHz, can be produced from nematic droplets in circularly polarized beams. Both droplet geometry and beam polarization influence the droplet rotation, allowing control of the phenomenon. Surprisingly, a chiral nematic droplet can sometimes undergo continuous rotation in a linearly polarized trap, a phenomenon caused by optically-induced changes in chirality. We describe this remarkable effect which demonstrates how the control of chirality through polarization can result in an optically driven transducer.

  6. Defects in liquid crystal nematic shells

    Science.gov (United States)

    Fernandez-Nieves, A.; Utada, A. S.; Vitelli, V.; Link, D. R.; Nelson, D. R.; Weitz, D. A.

    2006-03-01

    We generate water/liquid crystal (LC)/water double emulsions via recent micro-capillary fluidic devices [A. S. Utada, et.al. Science 308, 537 (2005)]. The resultant objects are stabilized against coalescence by using surfactants or adequate polymers; these also fix the boundary conditions for the director field n. We use 4-pentyl-4-cyanobiphenyl (5CB) and impose tangential boundary conditions at both water/LC interfaces by having polyvinyl alcohol (PVA) dispersed in the inner and outer water phases. We confirm recent predictions [D. R. Nelson, NanoLetters 2, 1125 (2002)] and find that four strength s=+1/2 defects are present; this is in contrast to the two s=+1 defect bipolar configuration observed for bulk spheres [A. Fernandez-Nieves, et.al. Phys. Rev. Lett. 92, 105503 (2004)]. However, these defects do not lie in the vertices of a tetrahedron but are pushed towards each other until certain equilibration distance is reached. In addition to the four defect shells, we observe shells with two s=+1 defects and even with three defects, a s=+1 and two s=+1/2. We argue these configurations arise from nematic bulk distortions that become important as the shell thickness increases. Finally, by adding a different surfactant, sodium dodecyl sulphate (SDS), to the outer phase, we can change the director boundary conditions at the outermost interface from parallel to homeotropic, to induce coalescing of the two pair of defects in the four defect shell configuration to yield two defect bipolar shells.

  7. (Liquid + liquid) equilibrium data for the ternary systems (cycloalkane + ethylbenzene + 1-ethyl-3-methylimidazolim ethylsulfate) at T = 298.15 K and atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Emilio J. [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain); Laboratory of Separation and Reaction Engineering, LSRE, Departamento de Engenharia Quimica, Facultade de Engenharia, Universidade de Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Calvar, Noelia, E-mail: noecs@uvigo.e [Laboratory of Separation and Reaction Engineering, LSRE, Departamento de Engenharia Quimica, Facultade de Engenharia, Universidade de Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Dominguez, Irene; Dominguez, Angeles [Departamento de Ingenieria Quimica de la Universidad de Vigo, 36310 Vigo (Spain)

    2011-05-15

    Research highlights: [EMim][ESO{sub 4}] was studied as solvent to extract ethylbenzene from cycloalkanes. (Liquid + liquid) equilibrium data were measured at 298.15K and atmospheric pressure. Selectivity and solute distribution ratio were obtained and compared with literature. Experimental data were satisfactorily correlated using NRTL and UNIQUAC models. [EMim][ESO{sub 4}] can be used as solvent for the studied (liquid + liquid) extraction. - Abstract: In this paper, (liquid + liquid) equilibrium (LLE) data for the ternary systems (cyclohexane, or cyclooctane, or methylcyclohexane + ethylbenzene + 1-ethyl-3-methylimidazolium ethylsulfate) have been determined experimentally at T = 298.15 K and atmospheric pressure. The solubility curves and the tie-line compositions of the conjugate phases were obtained by means of density. The degree of consistency of the tie-lines was tested using the Othmer-Tobias equation, and the Non-Random Two-Liquid (NRTL) and the Universal Quasi-Chemical (UNIQUAC) models were used to correlate the phase equilibrium in the systems. Selectivity and solute distribution ratio were evaluated for the immiscible region.

  8. Flexoelectricity of a Calamitic Liquid Crystal Elastomer Swollen with a Bent-core Liquid Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, M.; Verduzco, R; Gleeson, J; Sprunt, S; Jakli, A

    2009-01-01

    We have measured the electric current induced by mechanical distortion of a calamitic liquid crystal elastomer (LCE) swollen with a low molecular weight bent-core nematic (BCN) liquid crystal, and have determined, for the first time, the bend flexoelectric coefficient e{sub 3} of such a BCN-LCE composite. In one method, we utilize air-pressure to induce a mechanical bend deformation and flexoelectric polarization in a BCN-LCE film, and then measure the polarization current as a function of time. An alternative technique uses a rotary-motor driven scotch yoke to periodically flex the BCN-LCE; in this case, the magnitude and phase of the induced current are recorded via a lock-in amplifier. The flexoelectric coefficient, e{sub 3}, was found to be {approx}20 nC/cm{sup 2}, and is stable in magnitude from room temperature to {approx}65 C. It is about one third the value measured in samples of the pure BCN; this fraction corresponds closely to the molar concentration of BCN in the LCE. The flexoelectric current increases linearly with the magnitude of the bend deformation and decays with frequency. These observations indicate a promising way forward towards producing very low-cost, self-standing, rugged electromechanical energy conversion devices.

  9. Ferroelectric Nanoparticles in Liquid Crystals: Recent Progress and Current Challenges.

    Science.gov (United States)

    Garbovskiy, Yuriy; Glushchenko, Anatoliy

    2017-11-01

    The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i) the control of the size, shape, and the ferroelectricity of nanoparticles; (ii) the production of a stable and aggregate-free dispersion of relatively small (~10 nm) ferroelectric nanoparticles in liquid crystals; (iii) the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv) the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v) the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed.

  10. Ferroelectric Nanoparticles in Liquid Crystals: Recent Progress and Current Challenges

    Directory of Open Access Journals (Sweden)

    Yuriy Garbovskiy

    2017-11-01

    Full Text Available The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i the control of the size, shape, and the ferroelectricity of nanoparticles; (ii the production of a stable and aggregate-free dispersion of relatively small (~10 nm ferroelectric nanoparticles in liquid crystals; (iii the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed.

  11. Liquid crystals: a new topic in physics for undergraduates

    Science.gov (United States)

    Pavlin, Jerneja; Vaupotič, Nataša; Čepič, Mojca

    2013-05-01

    This paper presents a teaching module about liquid crystals. Since liquid crystals are linked to everyday student experiences and are also a topic of current scientific research, they are an excellent candidate for a modern topic to be introduced into education. We show that liquid crystals can provide a pathway through several fields of physics such as thermodynamics, optics and electromagnetism. We discuss what students should learn about liquid crystals and what physical concepts they should know before considering them. In the presentation of the teaching module, which consists of a lecture and experimental work in a chemistry and physics laboratory, we focus on experiments on phase transitions, polarization of light, double refraction and colours. A pilot evaluation of the module was performed among pre-service primary school teachers who have no special preference for natural sciences. The evaluation shows that the module is very efficient in transferring knowledge. A prior study showed that the informally obtained pre-knowledge on liquid crystals of the first-year students from several different fields of study was negligible. Since social science students are the least interested in natural sciences, it can be expected that students in any study programme will on average achieve at least as good qualitative knowledge of phenomena related to liquid crystals as the group involved in the pilot study.

  12. Reflective liquid crystal light valve with hybrid field effect mode

    Science.gov (United States)

    Boswell, Donald D. (Inventor); Grinberg, Jan (Inventor); Jacobson, Alexander D. (Inventor); Myer, Gary D. (Inventor)

    1977-01-01

    There is disclosed a high performance reflective mode liquid crystal light valve suitable for general image processing and projection and particularly suited for application to real-time coherent optical data processing. A preferred example of the device uses a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state. The liquid crystal thus modulates the polarization of the coherent read-out or projection light responsively to the non-coherent image. An analyzer is used to create an intensity modulated output beam.

  13. Lyotropic chromonic liquid crystals: From viscoelastic properties to living liquid crystals

    Science.gov (United States)

    Zhou, Shuang

    Lyotropic chromonic liquid crystal (LCLC) represents a broad range of molecules, from organic dyes and drugs to DNA, that self-assemble into linear aggregates in water through face-to-face stacking. These linear aggregates of high aspect ratio are capable of orientational order, forming, for example nematic phase. Since the microscopic properties (such as length) of the chromonic aggregates are results of subtle balance between energy and entropy, the macroscopic viscoelastic properties of the nematic media are sensitive to change of external factors. In the first part of this thesis, by using dynamic light scattering and magnetic Frederiks transition techniques, we study the Frank elastic moduli and viscosity coefficients of LCLC disodium cromoglycate (DSCG) and sunset yellow (SSY) as functions of concentration c , temperature T and ionic contents. The elastic moduli of splay (K1) and bend (K3) are in the order of 10pN, about 10 times larger than the twist modulus (K2). The splay modulus K1 and the ratio K1/K3 both increase substantially as T decreases or c increases, which we attribute to the elongation of linear aggregates at lower T or higher c . The bend viscosity is comparable to that of thermotropic liquid crystals, while the splay and twist viscosities are several orders of magnitude larger, changing exponentially with T . Additional ionic additives into the system influence the viscoelastic properties of these systems in a dramatic and versatile way. For example, monovalent salt NaCl decreases bend modulus K3 and increases twist viscosity, while an elevated pH decreases all the parameters. We attribute these features to the ion-induced changes in length and flexibility of building units of LCLC, the chromonic aggregates, a property not found in conventional thermotropic and lyotropic liquid crystals form by covalently bound units of fixed length. The second part of the thesis studies a new active bio-mechanical hybrid system called living liquid crystal

  14. Resolution of Ternary Mixture of Aspirin, Atorvastatin, and Clopidogrel by Chemometric-Assisted UV Spectroscopic and Liquid Chromatography Methods

    Directory of Open Access Journals (Sweden)

    Mahmoud Mohamed Issa

    2013-01-01

    Full Text Available Two chemometrics-assisted UV spectrophotometric methods were proposed for the resolution of ternary mixtures without any chemical pretreatment. The first method is based on modification of H-point standard addition method which permits simultaneous analysis of three species from a unique calibration set by making the simultaneous addition of the three analytes. Quotient between the spectra of aspirin, atorvastatin, and clopidogrel was obtained and the results showed that simultaneous determination of aspirin, atorvastatin, and clopidogrel can be obeyed in the linear range 2.5–20 μg mL−1 of aspirin, 2.5–17.5 μg mL−1 of atorvastatin, and 2.5–20 μg mL−1 of clopidogrel in ternary mixture. The second method is based on the combination of the first derivative spectra and Cramer's matrix rule. In the matrix calculation, clopidogrel has zero crossing point at 316.8 and 212 nm, while for atorvastatin the zero crossing point at 250 nm where the matrix is greatly simplified and easily solved. The linear concentration ranges were 2.5–20 μg mL−1 aspirin, 2.5–17.5 μg mL−1 atorvastatin and 2.5–20 μg mL−1 clopidogrel in ternary mixtures. The results proved that the simultaneous determination of aspirin, atorvastatin, and clopidogrel could be obeyed. Both methods were applied for capsules containing the three ingredients and results were in good concordance with alternative liquid chromatography.

  15. NMR studies of liquid crystals and molecules dissolved in liquid crystal solvents

    Energy Technology Data Exchange (ETDEWEB)

    Drobny, Gary Peter [Univ. of California, Berkeley, CA (United States)

    1982-11-01

    This thesis describes several studies in which nuclear magnetic resonance (nmr) spectroscopy has been used to probe the structure, orientation and dynamics of liquid crystal mesogens and molecules dissolved in liquid crystalline phases. In addition, a modern high field nmr spectrometer is described which has been used to perform such nmr studies. Chapter 1 introduces the quantum mechanical formalisms used throughout this thesis and briefly reviews the fundamentals of nuclear spin physics and pulsed nmr spectroscopy. First the density operator is described and a specific form for the canonical ensemble is derived. Then Clebsch-Gordon coefficients, Wigner rotation matrices, and irreducible tensor operators are reviewed. An expression for the equilibrium (Curie) magnetization is obtained and the linear response of a spin system to a strong pulsed r.f. irradiation is described. Finally, the spin interaction Hamiltonians relevant to this work are reviewed together with their truncated forms. Chapter 2 is a deuterium magnetic resonance study of two 'nom' liquid crystals which possess several low temperature mesomorphic phases. Specifically, deuterium quadrupolar echo spectroscopy is used to determine the orientation of the liquid crystal molecules in smectic phases, the changes in molecular orientation and motion that occur at smectic-smectic phase transitions, and the order of the phase transitions. For both compounds, the phase sequence is determined to be isotropic, nematic, smectic A, smectic C, smectic BA, smectic BC, and crystalline. The structure of the smectic A phase is found to be consistent with the well-known model of a two dimensional liquid in which molecules are rapidly rotating about their long axes and oriented at right angles to the plane of the layers. Molecules in the smectic C phase are found to have their long axes tilted with respect to the layer normal, and the tilt angle is temperature dependent, increasing from

  16. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber.

    Science.gov (United States)

    Zito, Gianluigi; Pissadakis, Stavros

    2013-09-01

    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a prepolymer/liquid crystal solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG, are discussed. Experimental data presented here demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal phase separation inside the PCF capillaries is examined using scanning electron microscopy, and is discussed further.

  17. Ordering in nematic liquid crystals from NMR cross-polarization ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... The measurement of dipolar couplings between nuclei is a convenient way of obtatining directly liquid crystalline ordering through NMR since the coupling is dependent on the average orientation of the dipolar vector in the magnetic field which also aligns the liquid crystal. However, measurement of the ...

  18. Ordering in nematic liquid crystals from NMR cross-polarization ...

    Indian Academy of Sciences (India)

    Abstract. The measurement of dipolar couplings between nuclei is a convenient way of obtatining directly liquid crystalline ordering through NMR since the coupling is dependent on the average orientation of the dipolar vector in the magnetic field which also aligns the liquid crystal. However, measurement of the dipolar ...

  19. Optical wave-mixing and photorefractivity in liquid crystals

    Science.gov (United States)

    Ding, Jianwu

    Optical wave-mixing has a lot of applications such as optical amplification, adaptive optics, harmonic wave generation, and multi-photon microscopy. Photorefractivity has been utilized in many important applications including high density optical data storage, image processing, spatial light modulation, phase conjugation, and optical limiting. They have been investigated, theoretically and experimentally, in this thesis, in the contexts of stimulated orientational scattering and photorefractivity in liquid crystals. Stimulated orientational scattering is a unique optical wave-mixing phenomenon that a scattered noise beam, generated by liquid crystal director oscillation, gets amplified through its interaction with the transmitted beam and director reorientation grating under an intense laser illumination. In this research work, I developed the first steady-state SOS theory without the compromise of non-pump-depletion approximation. I successfully implemented polarization conversion in the infrared wavelength regime and the experimental observations agree well with our developed theory. The control of an external AC field to the stimulated orientational scattering was also experimentally investigated. Furthermore, I investigated the dynamics of this liquid crystal director reorientational process by analyzing the Fourier spectrum of the stimulated signal. The influence of a modulating AC field to the stimulated signal was also studied. The oscillating frequency of the liquid crystal director grating agreed with theoretically calculated characteristic frequency. In addition, I have theoretically and experimentally studied the photorefractivity in liquid crystals. Based on the transport band model, the generated space charge field was developed. With the help of an externally applied DC field, the space charge field is able to induce liquid crystal director reorientation and analytical solutions have been derived for both the director reorientational angle and the

  20. Tunable waveguides based on liquid crystal-infiltrated silicon photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cos, Joaquin; Ferre-Borrull, Josep; Pallares, Josep; Marsal, Lluis F. [Universitat Rovira i Virgili, Nano-electronic and Photonic Systems, Avda. Paisos Catalans 26, 43007 Tarragona (Spain)

    2011-03-15

    A methodology for the study of the practical implementation of tunable waveguides based on Silicon Photonic Crystals with liquid crystal-infiltrated pores is presented. First, by using the FDTD method, the transmission properties of the waveguide depending on the liquid crystal optical axis orientation are studied. Then by means of the plane wave expansion method and taking into account the anisotropy of the photonic crystal components and considering adequate supercells, the transmission or rejection of the optical beam are explained. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Liquid-crystal order during synthesis affects main-chain liquid-crystal elastomer behavior.

    Science.gov (United States)

    Traugutt, N A; Volpe, R H; Bollinger, M S; Saed, M O; Torbati, A H; Yu, K; Dadivanyan, Natalia; Yakacki, C M

    2017-10-11

    This study presents the first direct comparison of the influence of liquid-crystal order during synthesis on the thermo-mechanical behaviors of main-chain liquid-crystal elastomers (LCEs) in thiol-acrylate networks. Six polydomain nematic elastomer (PNE) chemistries were compared directly by synthesizing with the mesogens in either an isotropic state (i-PNE) or a nematic state (n-PNE). The i-PNE networks were created in the presence of solvent, which disrupted any liquid-crystal order during network formation. Conversely, the n-PNE networks were created without the presence of solvent below the isotropic transition (TNI). Differential scanning calorimetry (DSC) was first performed, and it showed that i-PNE networks experienced a clearly defined nematic-to-isotropic transition upon heating, whereas the transition in n-PNE networks was unable to be identified, which may be the result of a nematic-to-paranematic phase transition. Dynamic mechanical analysis (DMA) tests revealed that while both networks maintained elevated loss tangent in the nematic region, only i-PNE networks prominently displayed dynamic soft elasticity behavior. The two-way shape switching behaviors of LCE networks were examined using actuation tests under a 100 kPa bias stress. It showed that the strain amplitude strongly depends on synthesis history; it ranges from 66% to 126% in i-PNE samples and 3% to 61% in n-PNE samples. To help interpret the different actuation strain behaviors between i-PNEs and n-PNEs, wide-angle X-ray scattering (WAXS) was then performed where the LCE samples were strained to 40%. The results showed that order parameter (S) in n-PNE samples (ranging from 0.37 to 0.50) is lower than that in i-PNE samples (0.54 for all cases), and the parameter decreased as the cross-linking density increased. The stress-strain behaviors of the LCE networks measured from uniaxial tension tests revealed that all i-PNE samples had a lower soft-elasticity plateau during loading compared to the

  2. Ternary liquid-liquid equilibrium for eugenol + tert-butanol + water system at 303.15 and 323.15K and atmospheric pressure

    Science.gov (United States)

    Sucipto, Retno Kumala Hesti; Kuswandi, Wibawa, Gede

    2017-05-01

    The objective of this study was to determine ternary liquid-liquid equilibrium for eugenol + tert-butanol + water system at 303.15 and 323.15K and atmospheric pressure. Using 25 mL equilibrium cell equipped jacketted water connected to water bath to maintain equilibrium temperature constant. The procedure of this experiment was conducted by inserting mixture of eugenol + tert-butanol + water system at certain composition into equilibrium cell. The solution was stirred for 4 hours and then was allowed for 20 hours in order to separate aqueous and organic phases completely. The temperature equilibrium cell of and the atmosphere pressure were recorded as equilibrium temperature and pressure for each measurenment. The equilibrium compositions of each phase were analyzed using Gas Chromatography. The experimental data obtained in this work were correlated with NRTL and UNIQUAC models with root mean square deviation between esperimental and calculated equilibrium compositions of 0.03% and 0.04% respectively.

  3. Quantum Dot/Liquid Crystal Nanocomposites in Photonic Devices

    Directory of Open Access Journals (Sweden)

    Andrea L. Rodarte

    2015-07-01

    Full Text Available Quantum dot/liquid crystal nano-composites are promising new materials for a variety of applications in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however, we need to control and stabilize nano-particle dispersion in different liquid crystal host phases and understand how the particles behave in an anisotropic fluid. An ideal system will allow for the controlled assembly of either well-defined nano-particle clusters or a uniform particle distribution. In this paper, we investigate mesogen-functionalized quantum dots for dispersion in cholesteric liquid crystal. These nanoparticles are known to assemble into dense stable packings in the nematic phase, and such structures, when localized in the liquid crystal defects, can potentially enhance the coupling between particles and a cholesteric cavity. Controlling the dispersion and assembly of quantum dots using mesogenic surface ligands, we demonstrate how resonant fluid photonic cavities can result from the co-assembly of luminescent nanoparticles in the presence of cholesteric liquid crystalline ordering.

  4. Novel Microstructures for Polymer-Liquid Crystal Composite Materials

    Science.gov (United States)

    Magda, Jules J.

    2004-01-01

    There are a number of interface-dominated composite materials that contain a liquid crystalline (LC) phase in intimate contact with an isotropic phase. For example, polymer- dispersed liquid crystals, used in the fabrication of windows with switchable transparency, consist of micron size LC droplets dispersed in an isotropic polymer matrix. Many other types of liquid crystal composite materials can be envisioned that might have outstanding optical properties that could be exploited in novel chemical sensors, optical switches, and computer displays. This research project was based on the premise that many of these potentially useful LC composite materials can only be fabricated under microgravity conditions where gravity driven flows are absent. In the ground-based research described below, we have focused on a new class of LC composites that we call thermotropic- lyotropic liquid crystal systems (TLLCs). TLLCs consist of nanosize droplets of water dispersed in an LC matrix, with surfactants at the interface that stabilize the structure. By varying the type of surfactant one can access almost an infinite variety of unusual LC composite microstructures. Due to the importance of the interface in these types of systems, we have also developed molecular simulation models for liquid crystals at interfaces, and made some of the first measurements of the interfacial tension between liquid crystals and water.

  5. Liquid crystals. Oligomeric and polymeric materials for soft photonic technologies

    CERN Document Server

    Coles, M J

    2002-01-01

    The current pace of today's information technologies might lead the casual observer to believe that this is all new. However the reality is that, as with most things, this is really a long evolution of processes based on tried, tested and re-adapted techniques. This thesis represents 12 years of predominantly technology driven research and covers a whole range of characterising, evaluating and fabricating devices based on liquid crystalline systems. Firstly polymer liquid crystals are discussed with respect to the fabrication of a flexible substrate display based on standard printing techniques and this is shown to have improved display viewing properties over a standard polymer dispersed liquid crystal (PDLC) device. Following on from this work is presented that involves the production of regular grid arrays in isotropic polymers that are used as control structures in nematic liquid crystal systems. This progresses onto a now patented device that allows the production of robust ferroelectric devices based on...

  6. Probing the electronic environment of binary and ternary ionic liquid mixtures by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Men, Shuang; Licence, Peter

    2017-10-01

    X-ray photoelectron spectroscopy is used to probe the electronic environment of cations and anions for three binary and one ternary chlorostannate ionic liquid mixtures. The impact of the weighting of Cl- on the electronic environment of the cation-based nitrogen atom is revealed in detail. With the increasing of the concentration of Cl-, the N 1s binding energy is decreased. The electronic environment of the anion-based component is also compared based upon Sn 3d5/2 and Cl 2p3/2 binding energies. It is found that with the increasing of the weighting of Cl-, binding energies of Sn 3d5/2 and Cl 2p3/2 both decrease.

  7. Enthalpy and phase behavior of coal derived liquid mixtures: Technical progress report for the period January-March 1987. [M-cresol/quinoline/tetralin ternary mixture

    Energy Technology Data Exchange (ETDEWEB)

    Yesavage, V.F.; Kidnay, A.J.

    1987-04-30

    On July 15, 1984, work was initiated on a program to study the enthalpy and phase behavior of coal derived liquid model compound mixtures. The objectives of this program are to study the enthalpy and phase behavior of a selected ternary model compound system, representative of interactions present in coal derived liquids. Measurements will be made in a Freon 11 reference fluid boil-off calorimeter, and an equilibrium flash vaporization apparatus. These experimental systems have already been developed. Previous studies have indicated that existing data and correlations developed for petroleum fluids are not applicable to coal derived liquids. This is due to the presence of significant concentrations of polar associating heteroatomics in the predominantly aromatic coal liquids. Thus, the ternary system will include an aromatic, a basic nitrogen compound, and a cresol. It is presently planned to study the m-cresol/quinoline/tetralin ternary mixture. Measurements will be made over a wide range of temperature (200 to 750/sup 0/F) and pressure (20 to 1500 psia), for the three pure compounds, the three binary mixtures and selected compositions of the ternary. Both enthalpy and phase behavior measurements will be made. This set of data will be useful as a standard for fitting and evaluating thermodynamic correlations and equations of state that are applicable to associating fluid mixtures, and thus to coal derived liquids. In particular we will attempt to fit both the enthalpy and phase behavior data with a single equation of state using local composition mixing rules and common interaction parameters. During the eleventh quarter, enthalpy measurements have been obtained for the ternary mixtures of m-cresol/quinoline/tetralin with molar ratios 2/3:1/6:1/6 and 1/6:2/3:1/6 m-cresol:quinoline:tetralin. The results are presented in Appendix A. The project has progressed very will during this quarter, and the enthalpy measurements have been completed. 2 refs., 2 figs., 2 tabs.

  8. Nanoscience with liquid crystals from self-organized nanostructures to applications

    CERN Document Server

    Li, Quan

    2014-01-01

    This book focuses on the exciting topic of nanoscience with liquid crystals: from self-organized nanostructures to applications. The elegant self-organized liquid crystalline nanostructures, the synergetic characteristics of liquid crystals and nanoparticles, liquid crystalline nanomaterials, synthesis of nanomaterials using liquid crystals as templates, nanoconfinement and nanoparticles of liquid crystals are covered and discussed, and the prospect of fabricating functional materials is highlighted. Contributions, collecting the scattered literature of the field from leading and active player

  9. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate

    Science.gov (United States)

    Yamaguchi, Akihiro; Smith, Gregory; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Clark, Noel

    2014-03-01

    Chromonic liquid crystals (CLCs) are formed when planar molecules dissolved in water stack into rod-like aggregates that can order as liquid crystals. Isotropic, nematic, and M-phases can be observed depending on the degree of molecular orientational and positional order by variation of the CLC concentration. We focused on mixtures of two well-known CLCs, Sunset Yellow, a food dye, and disodium cromoglycate (DSCG), an asthma medication. In order to study the phase behaviors of these mixtures, we observed their textures in glass cells and capillaries using polarized light microscopy. We report here a ternary phase diagram describing the complete phase behavior of the CLC mixtures. We observed a variety of phase behaviors depending on species ratio and concentration. In the isotropic phase, no clear phase separation of the two dyes was observed, while separation did occur in many nematic and M-phase combinations. We will also describe phase observations made using a light spectroscopy and bulk centrifugal partitioning. Grant support: NSF DMR 1207606 and NSF MRSEC DMR-0820579.

  10. Synthesis, crystal structure, and photoluminescent properties of ternary Cd(II)/triazolate/chloride system.

    Science.gov (United States)

    Wei, Gang; Shen, Yu-Feng; Li, Yong-Ru; Huang, Xiao-Chun

    2010-10-18

    Solvothermal reactions of cadmium chloride and 1,2,4-triazole (Htrz) in different solvent mediums have successfully synthesized five ternary Cd(II)/trz/Cl(-) complexes, [Cd(trz)Cl]·H(2)O (1·H(2)O), [Cd(4)(trz)(5)Cl(3)(H(2)O)]·(THF)(1.25)·(H(2)O)(2.5) (2·1.25THF·2.5H(2)O), [Cd(3)(trz)(2)Cl(MeCN)] (3), [Cd(3)(trz)(4)Cl(2)]·(H(2)O)(0.5) (4·0.5H(2)O), and [Cd(4)(trz)(6)Cl(2)(H(2)O)(0.5)]·(H(2)O)(3.5) (5·3.5H(2)O). All of these five coordination polymers have three-dimensional (3-D) structural features, which are constructed by distinct substructures including clusters, chains, rings, and even 3-D frameworks. In all cases, 1,2,4-triazolate adopts a μ(1,2,4) bridging mode, and chloride ions display a μ(2), μ(3), μ(4) bridging mode, respectively, which makes the structural diversity in the assembling system, for example, μ(4)-Cl and cadmium triazolate, build up an unprecedented tetranuclear cluster [Cd(4)(trz)(8)Cl](-) in 2. All of the materials exhibit intense blue fluorescent emission and high thermal stability, wherein 1 presents an interesting guest-responsive photoluminescent property.

  11. Morphology Tuning of Electrospun Liquid Crystal/Polymer Fibers.

    Science.gov (United States)

    Wang, Junren; Jákli, Antal; West, John L

    2016-10-05

    This paper elucidates the means to control precisely the morphology of electrospun liquid crystal/polymer fibers formed by phase separation. The relative humidity, solution parameters (concentration, solvent), and the process parameter (feed rate) were varied systematically. We show that the morphology of the phase-separated liquid crystal can be continuously tuned from capsules to uniform fibers with systematic formation of beads-on-a-string structured fibers in the intermediate ranges. In all cases, the polymer forms a sheath around a liquid-crystal (LC) core. The width of the polymer sheath and the diameter of the LC core increase with increasing feed rates. This is similar to the results obtained by coaxial electrospinning. Because these fibers retain the responsive properties of liquid crystals and because of their large surface area, they have potential applications as thermo-, chemo-, and biosensors. Because the size and shape of the liquid-crystal domains will have a profound effect on the performance of the fibers, our ability to precisely control morphology will be crucial in developing these applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Photonics of liquid-crystal structures: A review

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P., E-mail: palto@online.ru; Blinov, L. M.; Barnik, M. I.; Lazarev, V. V.; Umanskii, B. A.; Shtykov, N. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2011-07-15

    The original results of studies of the electro-optical and laser effects which have been performed at the Laboratory of Liquid Crystals of the Institute of Crystallography, Russian Academy of Sciences, over the last few years are reviewed. Cholesteric liquid crystals as vivid representatives of photonic structures and their behavior in an electric field are considered in detail. The formation of higher harmonics in the periodic distribution of the director field in a helical liquid crystal structure and, correspondingly, the new (anharmonic) mode of electro-optical effects are discussed. Another group of studies is devoted to bistable light switching by an electric field in chiral nematics. Polarization diffraction gratings controlled by an electric field are also considered. The results of studies devoted to microlasers on various photonic structures with cholesteric and nematic liquid crystals are considered in detail. Particular attention is given to the new regime: leaky-mode lasing. Designs of liquid crystal light amplifiers and their polarization, field, and spectral characteristics are considered in the last section.

  13. Theory of polymer-dispersed cholesteric liquid crystals.

    Science.gov (United States)

    Matsuyama, Akihiko

    2013-11-07

    A mean field theory is presented to describe cholesteric phases in mixtures of a polymer and a cholesteric liquid crystal. Taking into account an anisotropic coupling between a polymer and a liquid crystal, we examine the helical pitch, twist elastic constant, and phase separations. Analytical expressions of the helical pitch of a cholesteric phase and the twist elastic constant are derived as a function of the orientational order parameters of a polymer and a liquid crystal and two intermolecular interaction parameters. We also find isotropic-cholesteric, cholesteric-cholesteric phase separations, and polymer-induced cholesteric phase on the temperature-concentration plane. We demonstrate that an anisotropic coupling between a polymer and a liquid crystal can stabilize a cholesteric phase in the mixtures. Our theory can also apply to mixtures of a nematic liquid crystal and a chiral dopant. We discuss the helical twisting power, which depends on temperature, concentration, and orientational order parameters. It is shown that our theory can qualitatively explain experimental observations.

  14. Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Robert A. Shanks

    2012-01-01

    Full Text Available Liquid crystals are compounds that display order in the liquid state above the melting temperature and below the mesogenic isotropic temperature. Polymer-dispersed liquid crystals (PDLCs are composite materials in which liquid crystalline material is dispersed within a polymer matrix to form micron-sized droplets. The aim was to prepare several cholesteryl esters or alkoxybenzoic acid PDLCs and characterise thermal and optical properties. Differential scanning calorimetry and polarized optical microscopy were employed. The matrix polymer was a one-component UV-curable epoxy-acrylate resin. PDLCs were formed through entropy controlled phase separation resulting from UV-initiated crosslinking. The liquid crystals, both as mesogenic moieties and as dispersed droplets, exhibited various textures according to their molecular order and orientation. These textures formed in constrained regions separated by phase boundaries that occurred at temperatures characteristic of each liquid crystal used. The PDLC phase transitions occurred at temperatures lower than those exhibited by the mesogenic components in the neat state.

  15. Morphology, thermal properties and crystallization kinetics of ternary blends of the polylactide and starch biopolymers and nanoclay: The role of nanoclay hydrophobicity

    CSIR Research Space (South Africa)

    Wokadala, OC

    2015-08-01

    Full Text Available , 82–92 Morphology, thermal properties and crystallization kinetics of ternary blends of the polylactide and starch biopolymers and nanoclay: The role of nanoclay hydrophobicity Obiro Cuthbert Wokadala a, b , Suprakas Sinha Ray a, b, * , Jayita... of Applied Chemistry, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa c Department of Food Science, University of Pretoria, Pretoria 0001, South Africa Abstract Polylactide/butylated-starch/nanoclay (70/25.5/4.5 wt...

  16. Optical tuning of photonic bandgaps in dye-doped nematic liquid crystal photonic crystal fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard; Hermann, David Sparre

    2005-01-01

    An all-optical modulator is demonstrated, which utilizes a pulsed 532 nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal. In order to investigate the time response of the LCPBG fiber device, a low-power CW probe...

  17. Transverse wave propagation in photonic crystal based on holographic polymer-dispersed liquid crystal.

    Science.gov (United States)

    Fuh, Andy Ying-Guey; Li, Ming Shian; Wu, Shing Trong

    2011-07-04

    This study investigates the transversely propagating waves in a body-centered tetragonal photonic crystal based on a holographic polymer-dispersed liquid crystal film. Rotating the film reveals three different transverse propagating waves. Degeneracy of optical Bloch waves from reciprocal lattice vectors explains their symmetrical distribution.

  18. Synthesis and Liquid Chromatographic Determination of Optical Purity of Naphthyl Propionate Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seng Kue; Shin, Myung Soo; Lee, Jong Gun; Kang, Kyung Tae [Pusan National University, Busan (Korea, Republic of); Kim, Yong Bae [Konkuk University, Seoul (Korea, Republic of)

    2004-11-15

    Various types of optically pure naphthyl propionate liquid crystals were prepared from (S)-naproxen in a four step reaction sequence. We found that a commercial HPLC chiral column, (S,S)-Whelk-O1, successfully resolves the (S)-naproxen-based liquid crystals. This technique is very simple and effective in monitoring the enantiomeric excess of the intermediate and final products without any structural modification at all. Most ferro- and antiferroelectric liquid crystals are chiral and their mesomorphic phase structures and electro-optical properties are largely dependent on the optical purity. Thus, for the chiral liquid crystals the occurrence of chemical or thermal racemization has to be checked throughout the synthetic sequence and the investigation of the mesomorphic and electro-optical properties.

  19. Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

    Science.gov (United States)

    Charache, Greg W.; Baldasaro, Paul F.; Nichols, Greg J.

    1998-01-01

    A thermophotovoltaic energy conversion device and a method for making the device. The device includes a substrate formed from a bulk single crystal material having a bandgap (E.sub.g) of 0.4 eVternary or quaternary III-V semiconductor active layers.

  20. Phase Behavior at High Pressure of the Ternary System: CO2, Ionic Liquid and Disperse Dye

    Directory of Open Access Journals (Sweden)

    Helen R. Mazzer

    2012-01-01

    Full Text Available High pressure phase behavior experimental data have been measured for the systems carbon dioxide (CO2 + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6] and carbon dioxide (CO2 + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6] + 1-amino-2-phenoxy-4-hydroxyanthraquinone (C.I. Disperse Red 60. Measurements were performed in the pressure up to 18 MPa and at the temperature (323 to 353 K. As reported in the literature, at higher concentrations of carbon dioxide the phase transition pressure increased very steeply. The experimental data for the binary and ternary systems were correlated with good agreement using the Peng-Robinson equation of state. The amount of water in phase behavior of the systems was evaluated.

  1. Liquid Crystal Foams Generated by Pressure-Driven Microfluidic Devices.

    Science.gov (United States)

    Shi, Shuojia; Yokoyama, Hiroshi

    2015-04-21

    Thermotropic liquid crystals possess superior foaming capability without the aid of surfactants because of the anisotropic molecular structures. We developed a T-junction microfluidic device to inject gas bubbles of uniform size into a liquid crystal in the nematic and the smectic phases. The bubble size is primarily determined by the dimension of microfluidic channel regardless of the phase, and air bubbles of a few tens of micrometer diameter were stably injected at the rate up to 110 Hz to the close packing density with a polydispersity less than 4%. It is shown that an efficient path to fabricate stable liquid crystal foams is to inject bubbles in the nematic phase, where the highest injection rate is possible, and promptly cool it down to the smectic phase.

  2. Supercontinuum generation in fibers infiltrated with liquid crystals

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Bang, Ole; Lægsgaard, Jesper

    2006-01-01

    Supercontinuum generation in a capillary tube infiltrated with a nematic liquid crystal is investigated theoretically in the near infrared region. A liquid crystal with a high electronic nonlinearity is chosen, which makes it possible to generate 100 nm wide supercontinua using IO ps pulses...... with peak power 1.5 kW in a 10 cm long waveguide. The possibility of tuning the spectrum of the generated Supercontinuum by changing the dispersion of the waveguide is also considered. It is found that the broadening of the spectrum in both the normal and anomalous regime is mainly due to self phase...... modulation, and therefore the dispersion of the waveguide is only of minor importance. The tuning of the dispersion is achieved by varying the temperature of the liquid crystal inside the capillary...

  3. Scattering light interference from liquid crystal polymer dispersion films

    Science.gov (United States)

    Huang, Chi-Yen; Tsai, Ming-Shann; Lin, Chi-Huang; Fuh, Andy Y.

    2002-12-01

    The Quetelet-type ring pattern is observed in liquid crystal polymer dispersion (LCPD) films. The clusters of the polymer network and liquid crystal (LC) domains with different director axes in the LCPD films serve as scatterers. Cells with unidirectional and multidirectional rubbins are fabricated. Experimental results show that the polarization of incident light, the applied voltage and the ambient temperature significantly affect the ring intensities. However, the contribution of the LC domains is not evident until the voltage is applied. Finally, rubbing the cells in multiple directions reveals that measurement of the Quetelet-type ring intensity can be used to readily identify the orientation of the liquid crystals. This finding also reveals that the LCs in an LCPD mixture are aligned closer to the final rubbing direction than are pure LCs in a multidirectional rubbed cell. A simple model was proposed to explain the observations.

  4. Fast response and transparent optically isotropic liquid crystal diffraction grating.

    Science.gov (United States)

    Manda, Ramesh; Pagidi, Srinivas; Bhattacharyya, Surjya Sarathi; Park, Chul Ho; Lim, Young Jin; Gwag, Jin Seog; Lee, Seung Hee

    2017-10-02

    We have demonstrated an electrically tunable less polarization sensitive and fast response nanostructured polymer dispersed liquid crystal (nano-PDLC) diffraction grating. Fabricated nano-PDLC is optically transparent in visible wavelength regime. The optical isotropic nature was increased by minimizing the liquid crystal droplet size below visible wavelength thereby eliminated scattering. Diffraction properties of in-plane switching (IPS) and fringe-field switching (FFS) cells were measured and compared with one another up to four orders. We have obtained a pore-type polymer network constructed by highly interlinked polymer beads at which the response time is improved by strong interaction of liquid crystal molecules with polymer beads at interface. The diffraction pattern obtained by transparent nano-PDLC film has several interesting properties such as less polarization dependence and fast response. This device can be used as transparent tunable diffractor along with other photonic application.

  5. Optimization of electrically tunable VCSEL with intracavity nematic liquid crystal.

    Science.gov (United States)

    Belmonte, Carlos; Frasunkiewicz, Leszek; Czyszanowski, Tomasz; Thienpont, Hugo; Beeckman, Jeroen; Neyts, Kristiaan; Panajotov, Krassimir

    2015-06-15

    We optimize the wavelength tuning range of a Vertical-Cavity Surface-Emitting Laser with an intracavity layer of nematic Liquid Crystal (LC-VCSEL) lasing around 1.3 μm. The tunability is obtained by applying voltage to the liquid crystal layer, which esentially is to vary the refractive index from the extraordinary to the ordinary. We achieve 71.6 nm continuous tuning (without mode hopping) with liquid crystal thickness of about 3.2 μm. We investigate the impact of ambient temperature on the LC-VCSEL tuning range and show that mode-hop tuning can be achieved in the temperature range from -10°C to 50°C where the LC is in nematic phase.

  6. Selective crystallization of tank supernatant liquid

    Energy Technology Data Exchange (ETDEWEB)

    Herting, D.

    1996-10-01

    The objective of this task is to demonstrate the feasibility of selectively removing sodium nitrate (NaNO{sub 3}) from Hanford Site tank waste by a large-scale fractional crystallization process. Two thirds of all the nuclear waste stored in Hanford`s underground storage tanks is sodium nitrate (mass basis, excluding water). Fractional crystallization can remove essentially nonradioactive NaNO{sub 3} and other sodium salts from the waste, thereby reducing the volume of low-level waste glass by as much as 90%.

  7. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber

    OpenAIRE

    Zito, Gianluigi; Pissadakis, Stavros

    2013-01-01

    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG...

  8. Multichannel tunable filter properties of 1D magnetized ternary plasma photonic crystal in the presence of evanescent wave

    Science.gov (United States)

    Awasthi, Suneet Kumar; Panda, Ranjita; Shiveshwari, Laxmi

    2017-07-01

    The multichannel tunable filter properties of one-dimensional ternary plasma photonic crystal composed of magnetized plasma and lossless dielectric have been theoretically investigated using transfer matrix method in the microwave region. The proposed filters possess 2N - 2 comb-like sharp resonant peaks also called transmission channels for N > 1 in transmission spectra in the absence and presence of an external magnetic field. Due to the coupling between evanescent waves and propagating modes in plasma and dielectric layers, respectively, 2N - 2 transmission channels are found without the addition of any defect, enabling the structure to work as a multichannel filter. Next, the filter properties can be made tunable by the application of an external magnetic field, i.e., channel frequency can either be red or blue shifted depending upon the orientation of an external magnetic field. The number of channels and their positions can also be modulated by changing the number of periods (N) and the incident angle (θo), respectively, for both transverse electric (TE) and transverse magnetic (TM) modes besides other parameters such as plasma collision frequency, thickness of the plasma layer, plasma frequency, etc.

  9. Tuning the defect mode in ternary photonic crystal with external voltage for designing a controllable optical filter

    Science.gov (United States)

    Jamshidi-Ghaleh, Kazem; Rashidi, Shiva; Vahedi, Ali

    2015-09-01

    In this work, behavior of defect mode in one-dimensional ternary photonic crystal (1DTPC) structure with arrangement of (MgF2/Ag/TiO2)5LiNbO3(TiO2/Ag/MgF2)5 was investigated under the applied external electric dc voltage. The defect layer is lithium niobate (LiNbO3), an electro-optical (EO) material whose refractive index is voltage-dependent with high EO coefficient. In comparison, magnesium fluoride (MgF2) and titanium dioxide (TiO2) layers have very low EO coefficients. A narrow localized defect mode with perfect transmittance was appeared inside the photonic band gap. Under applying the positive or negative biases, red shift and blue shift was observed in the defect mode, respectively. More than 120 nm tunability was obtained under externally applied voltage in the range of -200 V to 200 V. The physical interpretation is very simple. Change in optical path-length displaces the localized wavelength of the defect mode due to Bragg interface condition. The externally tunable localized mode can be employed in designing a controllable optical filter, one of the essential devices for new-generation all-optical integrated circuits.

  10. Molecular dynamics simulations of liquid crystals at interfaces

    CERN Document Server

    Shield, M

    2002-01-01

    Molecular dynamics simulations of an atomistic model of 4-n-octyl-4'-cyanobiphenyl (8CB) were performed for thin films of 8CB on solid substrates (a pseudopotential representation of the molecular topography of the (100) crystal surface of polyethylene (PE), a highly ordered atomistic model of a pseudo-crystalline PE surface and an atomistic model of a partially orientated film of PE), free standing thin films of 8CB and 8CB droplets in a hexagonal pit. The systems showed strong homeotropic anchoring at the free volume interface and planar anchoring at the solid interface whose strength was dependent upon the surface present. The free volume interface also demonstrated weak signs of smectic wetting of the bulk. Simulations of thin free standing films of liquid crystals showed the ordered nature of the liquid crystals at the two free volume interfaces can be adopted by the region of liquid crystal molecules between the homeotropic layer at each interface only if there is a certain number of liquid crystal mole...

  11. Synthesis and mesomorphic properties of rigid-core ionic liquid crystals

    NARCIS (Netherlands)

    Kouwer, P.H.J.; Swager, T.M.

    2007-01-01

    Ionic liquid crystals combine the unique solvent properties of ionic liquids with self-organization found for liquid crystals. We report a detailed analysis of the structure-property relationship of a series of new imidazolium-based liquid crystals with an extended aromatic core. Investigated

  12. Ellipsometric study of vertically aligned nematic liquid crystals

    Science.gov (United States)

    Marino, A.; Santamato, E.; Bennis, N.; Quintana, X.; Otón, J. M.; Tkachenko, V.; Abbate, G.

    2009-01-01

    The director tilt angle distribution in vertically aligned nematic liquid crystal displays has been investigated by means of variable angle spectroscopic ellipsometry. Liquid crystal vertical alignment has been realized by thermal evaporation of SiOx. By changing the deposition angle, it is possible to control the pretilt angle. The director profile inside the sample was inferred by reflection and transmission ellipsometric measurements. The tilt angle distribution inside the cell versus the applied voltage is reported and eventually, comparing it with the simulations from the elastic theory, the anchoring energy has been obtained.

  13. Observations of dynamic stall phenomena using liquid crystal coatings

    Science.gov (United States)

    Reda, Daniel C.

    1991-01-01

    Novel, shear stress-sensitive/temperature-insensitive liquid crystal coatings have been applied to the surface of an oscillating airfoil in order to ascertain the unsteady fluid physics associated with the dynamic-stall process. Surface microtufts and laser sheet/smoke-particle flow visualization were used to compare the liquid-crystal results. Boundary-layer transition and turbulent separation locations were measured as a function of geometric angle of attack. The results obtained are compared with Eppler (1980) aerodynamic design code predictions.

  14. A Microwave Tunable Bandpass Filter for Liquid Crystal Applications

    Science.gov (United States)

    Cao, Weiping; Jiang, Di; Liu, Yupeng; Yang, Yuanwang; Gan, Baichuan

    2017-07-01

    In this paper, a novel microwave continuously tunable band-pass filter, based on nematic liquid crystals (LCs), is proposed. It uses liquid crystal (LC) as the electro-optic material to mainly realize frequency shift at microwave band by changing the dielectric anisotropy, when applying the bias voltage. According to simulation results, it achieves 840 MHz offset. Comparing to the existing tunable filter, it has many advantages, such as continuously tunable, miniaturization, low processing costs, low tuning voltage, etc. Thus, it has shown great potentials in frequency domain and practical applications in modern communication.

  15. Compact electrically controlled broadband liquid crystal photonic bandgap fiber polarizer

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm.......An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm....

  16. A Review of Polymer-Stabilized Ferroelectric Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2014-05-01

    Full Text Available The polymer stabilized state of ferroelectric liquid crystals (FLC is reviewed; and the effect of a dispersed polymer network in an FLC outlined and discussed. All fundamental material aspects are demonstrated; such as director tilt angle; spontaneous polarization; response time and viscosity; as well as the dielectric modes. It was found that the data can largely be explained by assuming an elastic interaction between the polymer network strands and the liquid crystal molecules. The elastic interaction parameter was determined; and increases linearly with increasing polymer concentration.

  17. A Review of Polymer-Stabilized Ferroelectric Liquid Crystals.

    Science.gov (United States)

    Dierking, Ingo

    2014-05-06

    The polymer stabilized state of ferroelectric liquid crystals (FLC) is reviewed; and the effect of a dispersed polymer network in an FLC outlined and discussed. All fundamental material aspects are demonstrated; such as director tilt angle; spontaneous polarization; response time and viscosity; as well as the dielectric modes. It was found that the data can largely be explained by assuming an elastic interaction between the polymer network strands and the liquid crystal molecules. The elastic interaction parameter was determined; and increases linearly with increasing polymer concentration.

  18. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber

    CERN Document Server

    Zito, Gianluigi

    2013-01-01

    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal phase separation inside the PCF capillaries is examined using scanning electron microscopy, while further discussed.

  19. Hydrothermal decomposition of liquid crystal in subcritical water

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Xuning [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China); Shanghai Cooperative Centre for WEEE Recycling, Shanghai Second Polytechnic University, No. 2360 Jinhai Road, Shanghai 201209 (China); He, Wenzhi, E-mail: hithwz@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China); Li, Guangming; Huang, Juwen; Lu, Shangming; Hou, Lianjiao [State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, No. 1239 Siping Road, Shanghai 200092 (China)

    2014-04-01

    Highlights: • Hydrothermal technology can effectively decompose the liquid crystal of 4-octoxy-4'-cyanobiphenyl. • The decomposition rate reached 97.6% under the optimized condition. • Octoxy-4'-cyanobiphenyl was mainly decomposed into simple and innocuous products. • The mechanism analysis reveals the decomposition reaction process. - Abstract: Treatment of liquid crystal has important significance for the environment protection and human health. This study proposed a hydrothermal process to decompose the liquid crystal of 4-octoxy-4′-cyanobiphenyl. Experiments were conducted with a 5.7 mL stainless tube reactor and heated by a salt-bath. Factors affecting the decomposition rate of 4-octoxy-4′-cyanobiphenyl were evaluated with HPLC. The decomposed liquid products were characterized by GC-MS. Under optimized conditions i.e., 0.2 mL H{sub 2}O{sub 2} supply, pH value 6, temperature 275 °C and reaction time 5 min, 97.6% of 4-octoxy-4′-cyanobiphenyl was decomposed into simple and environment-friendly products. Based on the mechanism analysis and products characterization, a possible hydrothermal decomposition pathway was proposed. The results indicate that hydrothermal technology is a promising choice for liquid crystal treatment.

  20. Photoresponsive Liquid Crystals Based on Dihydroazulene

    DEFF Research Database (Denmark)

    Petersen, Anne Ugleholdt

    The main focus of this thesis was a study upon photoresponsive liquid crystalline materials,with a starting point on the photoactive compound dihydroazulene (DHA). It has been shown thatsome DHAs with liquid crystalline properties can be synthesized, having an aliphatic substituent atthe 2-position....... Irradiation of such a DHA in the nematic phase gave partial conversion to avinylheptafulvene (VHF), not showing any changes in the mesophase, though a higher alignmentwas obtained when this sample was irradiated in its liquid crystalline state.Photomicrographs of the DHA under crossed polarizers before...... irradiation, after irradiation and when allowed toclose back to the DHAFor a disubstituted DHAs, with substituents in both the 2- and 7-positions, it was shown thatthese materials were unstable when heated above 100 °C, leading to side reactions, whichcomplicated analysis of the system. When doped...

  1. Fractional crystallization and zoning in igneous feldspars: ideal water-buffered liquid fractionation lines and feldspar zoning paths

    Science.gov (United States)

    Brown, William L.

    1993-01-01

    Diagrams giving plagioclase and sanidine fractionation paths and liquid fractionation lines under conditions of ideal water-buffered fractional crystallization in the ternary feldspar system were constructed graphically using topological reasoning, and experimental data and calculated phase relationships from the literature. The liquidus lines and solidus or solvus paths are unique at constant P and a H 2O. The composition of a liquid evolves with time and moves along a fractionation line by removal of successive crystal fractions, whereas the compositions of each of the crystal fractions lie on and define a solidus or solvus path. Most but not all such water-buffered lines and paths differ only slightly from those in which water is free to build up during crystallization and a H 2O to increase, as in many rocks. Liquid compositions lying along liquidus fractionation lines are not normally preserved, unless erupted as aphyric lavas. The solidus or solvus paths may be preserved either as overgrowth zones in crystals (zoning paths) or as a series of crystal fractions in layered intrusions. The topologies of the lines and paths depend mainly on the nature of the two-feldspar boundary line separating the plagioclase and sanidine fields which is a function of P H 2O or a H 2O at constant P; increases in either progressively lower the liquidi and solidi and cause larger intersections of the solidi with the solvus. One-feldspar solidus paths at high P and a H 2O are simple, whereas they are complex and may bend back on themselves at low P H 2O or low a H 2O at high P. Two-feldspar paths may be simultaneous (cotectic) or sequential (peritectic). The former are simple and do not meet at high P and a H 2O, the critical solution line lying in the gap; they are complex and may bend back or overlap at low P H 2O or low a H 2O at high P, the position of the critical solution line being hard to determine. Liquids which have simultaneously fractionated two feldspars may

  2. A study on interfacial tension between flexible polymer and liquid crystal.

    Science.gov (United States)

    Wu, Youjun; Yu, Wei; Zhou, Chixing

    2006-06-15

    The interfacial property in polymer-liquid crystal systems is quite different from flexible polymer-polymer mixtures due to the anisotropic properties of liquid crystals. The apparent interfacial tension between a liquid crystal and a flexible polymer was measured by deformed droplet retraction method. The deformation and recovery of a single liquid crystal droplet dispersed in a poly(dimethylsiloxane) matrix were realized by a transient shear flow and observed by polarized optical microscope. The apparent interfacial tension of polymer-liquid crystal system was found to be greatly dependent on the temperature, initial droplet deformation and liquid crystal droplet size.

  3. Computation of Isobaric Vapor-Liquid Equilibrium Data for Binary and Ternary Mixtures of Methanol, Water, and Ethanoic Acid from T, p, x, and HmE Measurements

    Directory of Open Access Journals (Sweden)

    Daming Gao

    2012-01-01

    Full Text Available Vapor-liquid equilibrium (VLE data for the strongly associated ternary system methanol + water + ethanoic acid and the three constituent binary systems have been determined by the total pressure-temperature-liquid-phase composition-molar excess enthalpy of mixing of the liquid phase (p, T, x, HmE for the binary systems using a novel pump ebulliometer at 101.325 kPa. The vapor-phase compositions of these binary systems had been calculated from Tpx and HmE based on the Q function of molar excess Gibbs energy through an indirect method. Moreover, the experimental T, x data are used to estimate nonrandom two-liquid (NRTL, Wilson, Margules, and van Laar model parameters, and these parameters in turn are used to calculate vapor-phase compositions. The activity coefficients of the solution were correlated with NRTL, Wilson, Margules, and van Laar models through fitting by least-squares method. The VLE data of the ternary system were well predicted from these binary interaction parameters of NRTL, Wilson, Margules, and van Laar model parameters without any additional adjustment to build the thermodynamic model of VLE for the ternary system and obtain the vapor-phase compositions and the calculated bubble points.

  4. Binary, ternary and quaternary liquid-liquid equilibria in 1-butanol, oleic acid, water and n-heptane mixtures

    NARCIS (Netherlands)

    Winkelman, J. G. M.; Kraai, G. N.; Heeres, H. J.

    2009-01-01

    This work reports on liquid-liquid equilibria in the system 1-butanol, oleic acid, water and n-heptane used for biphasic, lipase catalysed esterifications. The literature was studied on the mutual solubility in binary systems of water and each of the organic components. Experimental results were

  5. Measurement of (liquid + liquid) equilibria for ternary systems of (N-formylmorpholine + benzene + cyclohexane) at temperatures (303.15, 308.15, and 313.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Seyedein Ghannad, S. MohammadReza [School of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35195-363 (Iran, Islamic Republic of); Lotfollahi, Mohammad Nader, E-mail: mnlotfollahi@semnan.ac.i [School of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35195-363 (Iran, Islamic Republic of); Haghighi Asl, Ali [School of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35195-363 (Iran, Islamic Republic of)

    2011-06-15

    Research highlights: LLE were measured for (NFM+benzene+cyclohexane) at temperatures (303.15, 308.15 and 313.15) K. UNIQUAC and NRTL models were used to correlate the LLE. The reliability of the experimental data was tested by the Othmer-Tobias correlation. The obtained RMSDs are 0.0367 for NRTL model and 0.0539 for UNIQUAC model. - Abstract: This work demonstrates the ability of N-formylmorpholine (NFM) to act as an extraction solvent for the removal of benzene from its mixture with cyclohexane. The (liquid + liquid) equilibria (LLE) were measured for a ternary system of {l_brace}N-formylmorpholine (NFM) + benzene + cyclohexane{r_brace} under atmospheric pressure and at temperatures (303.15, 308.15, and 313.15) K. The experimental distribution coefficients (K) and selectivity factors (S) were obtained to reveal the extractive effectiveness of the solvent for separation of benzene from cyclohexane. The LLE results for the system studied indicate that increasing temperature decreases selectivity of the solvent. The reliability of the experimental results was tested by applying the Othmer-Tobias correlation. In addition, the universal quasichemical activity coefficient (UNIQUAC) and the non-random two liquids equation (NRTL) were used to correlate the LLE data using the interaction parameters determined from the experimental data. The root mean square deviations (RMSDs) obtained comparing calculated and experimental two-phase compositions are 0.0367 for the NRTL model and 0.0539 for the UNIQUAC model.

  6. Demonstration of liquid crystal for barocaloric cooling application

    OpenAIRE

    Xie, Zhongjian; Zhu, Yao

    2016-01-01

    Current vapor-compression technology is based on the gas-liquid transition of hazardous gas. The alternative cooling technology focuses on the solid caloric material. A new liquid barocaloric material, i.e. the liquid crystal, is proved to be potential for cooling application primarily (based on other literatures). Its phase transition needs a small stress (tens of MPa) and can be operated near room temperature. It has a large entropy change of ~200 J.K-1.kg-1 (0.2 J.K-1.cm-1). There is no br...

  7. Page 1 Hydrodynamics of cholesteric liquid crystals 337 which ...

    Indian Academy of Sciences (India)

    Also this has temperature and density fluctuations associated with it. 4.2 Permeation effects. (1) Plug flow: Cholesteric liquid crystals exhibit enormous viscosities in capillary flow. (Porter et al 1966). This may be interpreted to mean that the viscosity coefficients O's are large. However, as was first suggested by Helfrich (1969; ...

  8. Synthesis of liquid-crystal vanadyl complex with Schiff base

    Energy Technology Data Exchange (ETDEWEB)

    Galyametdinov, Yu.G.; Ivanova, G.I.; Ovchinnikov, I.V. (AN SSSR, Kazan. Fiziko-Tekhnicheskij Inst.)

    1984-12-01

    The paramagnetic Schiff base vanadyl (4) complex (4-octiloxy-N-(2-hydroxy-4-heptyloxybenziliden aniline) possessing liquid-crystal properties is obtained. The complex is synthesized by heating Schiff base with vanadyl acetate in absolute ethanol with the 65% yield. The IR and EPR spectra are measured.

  9. Orientational bistability in ferronematic liquid crystals with negative diamagnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Zakhlevnykh, A.N., E-mail: anz@psu.ru; Petrov, D.A.

    2015-11-01

    In the framework of continuum theory we study magnetic field induced orientational transitions in a ferronematic, i.e. suspension of single-domain magnetic particles in a nematic liquid crystal. We consider the case of negative diamagnetic susceptibility anisotropy of a liquid crystal and soft planar coupling of impurity particles with a liquid crystal matrix. We found tricritical behavior of the threshold transition in a magnetic field from perturbed state into uniform planar state. This transition can be the first or second order, depending on the parameter of the magnetic phase segregation. We analytically derive the expression for the tricritical segregation parameter that determines the character of a transition. We show that ferronematic has a large magneto-optical non-linearity which is the result of the director reorientation under external field. Comparison of results of numerical calculations with experimental data has been carried out. - Highlights: • We study orientational and magnetooptical properties of ferronematics. • We obtain the phase diagram for soft coupling of nanoparticles and liquid crystal. • We examine the character of magnetic field induced orientational transitions. • We found tricritical behavior of the transition from perturbed to uniform state. • We study the optical phase lag and the capacity of ferronematic cell.

  10. Cholesteric carbohydrate liquid crystals incorporating an intact glucopyranose moiety

    NARCIS (Netherlands)

    Smits, E; Engberts, J.B.F.N.; Kellogg, R.M; van Doren, H.A.

    1997-01-01

    Recently, the first monosaccharide derivatives containing a fully intact monosaccharide and two vicinal OH-groups which display thermotropic chiral mesophases were synthesized. These liquid crystals have a rigid core, with a trans-decalin-like skeleton incorporating the D-glucopyranose ring,

  11. Pixel size and pitch measurements of liquid crystal spatial light ...

    Indian Academy of Sciences (India)

    We present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator (SLM). The proposed method is based on optical diffraction from pixelated LC panel that has been modeled as a two-dimensional array of rectangular apertures. A novel yet simple, two-plane ...

  12. Advances in chemical physics advances in liquid crystals

    CERN Document Server

    Prigogine, Ilya; Vij, Jagdish K

    2009-01-01

    Prigogine and Rice's highly acclaimed series, Advances in Chemical Physics, provides a forum for critical, authoritative reviews of current topics in every area of chemical physics. Edited by J.K. Vij, this volume focuses on recent advances in liquid crystals with significant, up-to-date chapters authored by internationally recognized researchers in the field.

  13. Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

    Directory of Open Access Journals (Sweden)

    Mina Musashi

    2014-07-01

    Full Text Available Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid crystal gel was also applied topically to human facial skin, and analysis was conducted using before-and-after photographs of age spots, measurements of L* values that reflect degree of skin pigmentation, single-layer samples of the stratum corneum obtained via tape-stripping, and measurements of trans-epidermal water loss that reflect the status of the skin’s barrier function. The results suggested that cost-effective creams containing as low as 5% liquid crystal gel might be effective and safely sold as skin care products targeting age spots and other problems relating to uneven skin pigmentation.

  14. Lasing from dye-doped planar cholesteric liquid crystal devices

    Science.gov (United States)

    Wu, Ri-na; Dai, Qin; Yan, Bin; Liu, Yan-juan; Xu, Song-ning; Quan, Wei

    2011-06-01

    The lasing action of dye doped cholesteric liquid crystal (CLC) cell was investigated in this work. A planar state was prepared by antiparallel rubbing process ITO glasses with polymide layer coating. The dye doped cholesteric liquid crystal mixture was used by mixing a laser dye DCM, a chiral agent CB15 and a nematic liquid crystal TEB30A. A second harmonic Q-switched Nd:YAG pulsed laser (λ=532nm) was used as the pumping source. A sharp peak was measured at 611 nm in the cell-normal direction and cell-plane direction after reaching threshold pump energy. The least full width of half maximum (FWHM) were about 10 nm and 12 nm. The optical structure of the device was investigated upon applied voltage. The results show that planar state of the CLCs is a prerequisite for the generation of lasing emission. So laser emission attributed to the photonic band gap (Bragg mode) in the cell-normal direction in which the helical axis exists. Due to the waveguide structure formed by the liquid crystal sandwiched between glass substrates (ne=1.522, no=1.692>ng=1.50), quasi-in-plane leaky lasing modes exist in the cell-plane direction.

  15. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Science.gov (United States)

    2010-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... screening for detection of breast cancer or other uses—(1) Identification. A nonelectrically powered or an... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device...

  16. Aggregation Properties of the Chromonic Liquid Crystal Benzopurpurin 4B

    Science.gov (United States)

    McKitterick, Christopher; Collings, Peter

    2009-03-01

    Benzopurpurin 4B (BPP) is a textile dye very similar to the common indicator Congo Red. As is true for all chromonics, the absorption spectrum is concentration dependent at low concentrations. If this dependence is used to estimate a free energy change for aggregation, it is higher than has been determined for other systems. Unlike other recently investigated chromonic liquid crystals, BPP forms a liquid crystal phase at extremely low concentrations, about 0.5 wt%. Also unlike these other chromonic liquid crystals, the aggregation kinetics are exceedingly slow. X-ray diffraction and light scattering measurements indicate that the aggregates of BPP are much larger than for chromonic systems that form liquid crystals at higher concentrations. BPP aggregates can be imaged using confocal microscopy, revealing a length distribution centered at 3 μm for a solution forced through a 0.2 μm filter. Over days the aggregates lengthen to well over 10 μm. The diameter of the aggregate images is slightly greater than the diffraction limit of the microscope, placing an upper limit on the diameter of 0.14 μm. These dimensions are consistent with the light scattering results.

  17. LIQUID CRYSTAL POLYMERS (LCP) USED AS A MACHINING FLUID CD

    Science.gov (United States)

    This interactive CD was produced to present the science, research activities, and beneficial environmental and machining advantages for utilizing Liquid Crystal Polymers (LCPs) as a machine fluid in the manufacturing industry.In 1995, the USEPA funded a project to cut flu...

  18. A linear polymerized photopolymer orienting a nematic liquid crystal ...

    Indian Academy of Sciences (India)

    formalism. OZHAN KAYACAN. Department of Physics, Faculty of Arts and Sciences, Celal Bayar University, ..... To this end, we used De Jeu's expression for ∆n = n − n⊥ [15], which is used elsewhere [5]; this ... of the orientational degrees of freedom of the liquid crystal molecules to the entropy of the system. Therefore, the ...

  19. Bidimensional distortion in ferroelectric liquid crystals with strong ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... In the last decade, it has been experimentally found that in certain conditions a periodic domain pattern arises in ferroelectric liquid crystals (FLC) in bookshelf geometry. Such a periodic texture appears after switching-off an external electric field, even in strong anchoring conditions. It has a static character ...

  20. Nonlinear response studies and corrections for a liquid crystal ...

    Indian Academy of Sciences (India)

    portant in several optical processing and imaging applications, is suggested. Further, the necessity to compensate the SLM image nonlinearities in a volume holographic data storage and retrieval system is demonstrated. Keywords. Liquid crystal spatial light modulator; holographic data storage; optical image processing.

  1. Red blood cells aligning inside innovative liquid crystal cell

    Science.gov (United States)

    Likhomanova, S. V.; Kamanin, A. A.; Kamanina, N. V.

    2017-11-01

    Investigation results of red blood cells (human erythrocytes) aligning and fixing inside the liquid crystal (LC) cell have been presented in the present paper. LC cells have been modified through the improved nanostructured relief and LC sensitized with intermolecular charge transfer complex COANP-C70.

  2. Polymer Crystals Formed at Liquid-Liquid Interface Show Broken Symmetry

    Science.gov (United States)

    Wang, Wenda; Qi, Hao; Huang, Ziyin; Li, Christopher Y.; Soft Matter Research Group Team

    2015-03-01

    Curved space is incommensurate with typical ordered structures with three-dimensional translational symmetry. However, upon assembly, soft matter, including colloids, amphiphiles, and block copolymers, often form structures depicting curved surface/interface. On the other hand, twisted and curved crystals are often observed in crystalline polymers. Various mechanisms have been proposed for these non-flat crystalline morphologies. In this presentation, we will discuss the recent development of crystallization at flat and curved liquid/liquid (L/L) interface. We show that structure, morphology and chain folding behaviors are strongly affected by L/L interfacial energy and polymer chain ends. Both polyethylene and poly-L-lactic acid single crystal shells have been obtained using curved L/L interface. Polymer crystallization behavior at L/L interface will be compared with solution and bulk crystallization.

  3. HIGH-PRESSURE VAPOR-LIQUID EQUILIBRIUM DATA FOR BINARY AND TERNARY SYSTEMS FORMED BY SUPERCRITICAL CO2, LIMONENE AND LINALOOL

    Directory of Open Access Journals (Sweden)

    MELO S. A. B. VIEIRA DE

    1999-01-01

    Full Text Available The feasibility of deterpenating orange peel oil with supercritical CO2 depends on relevant vapor-liquid equilibrium data because the selectivity of this solvent for limonene and linalool (the two key components of the oil is of crucial importance. The vapor-liquid equilibrium data of the CO2-limonene binary system was measured at 50, 60 and 70oC and pressures up to 10 MPa, and of the CO2-linalool binary system at 50oC and pressures up to 85 bar. These results were compared with published data when available in the literature. The unpublished ternary phase equilibrium of CO2-limonene-linalool was studied at 50oC and up to 9 MPa. Selectivities obtained using these ternary data were compared with those calculated using binary data and indicate that a selective separation of limonene and linalool can be achieved.

  4. Distinctive features of a crystal, crystal-like properties of a liquid and atomic quantum effects

    Energy Technology Data Exchange (ETDEWEB)

    Pavlov, V V [Ural State Mining University. Kuibyshev str. 30, Ekaterinburg, 620144 (Russian Federation)], E-mail: gmf.chm@ursmu.ru

    2008-02-15

    It is believed that 'a crystal is similar to the crowd which is tightly compressed within enclosed space' and its structure in the simplest case is similar to the closest ball packing. Based on this assumption the strength of a crystal, long range ordering, the granular structure, capability for polymorphic transformation etc. were deduced. In a liquid such properties are impossible even in feebly marked form. However some of crystal-like features of melts are revealed in experiments and they frequently remain unacknowledged with a theory. From the other hand, computer model of crystal does not give even listed distinctive features of a crystal state. In the classical model the solidification more than to sunflower oil consistence was not obtained. It is possible to reach the real solidification if quantum 'freezing' of a part of atomic degrees of freedom would taken into account and any movement would stopped at zero energy level. There are some reasons to believe that another crystal properties and corresponding crystal-like features of liquids also can be got basing on these atomic quantum effects. In this case the reasons of many discussions on 'heredity', 'memory' of liquid and its microheterogeneity disappear.

  5. Phase relationships in the {Ho, Er}–Ni–Sn ternary systems at 673 K and crystal structure of new ternary compounds

    Energy Technology Data Exchange (ETDEWEB)

    Romaka, L., E-mail: romakal@franko.lviv.ua [Ivan Franko L’viv National University, Kyryl & Mephodiy Str. 6, 79005 L’viv (Ukraine); Romaniv, I. [Ivan Franko L’viv National University, Kyryl & Mephodiy Str. 6, 79005 L’viv (Ukraine); Romaka, V.V. [Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Pavlyuk, V. [Ivan Franko L’viv National University, Kyryl & Mephodiy Str. 6, 79005 L’viv (Ukraine)

    2015-05-15

    Highlights: • Ho–Ni–Sn and Er–Ni–Sn phase diagrams were constructed at 673 K. • Eight ternary compounds exist in both investigated systems. • HoNi{sub x}Sn{sub 2} (up to 7 at.% Ni) and ErNi{sub x}Sn{sub 2} (up to 5 at.% Ni) solid solutions were found. - Abstract: The phase equilibria of the Ho–Ni–Sn and Er–Ni–Sn ternary systems were studied at 673 K in the whole concentration range using electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD). Each system is characterized by formation of eight ternary compounds at 673 K: Ho{sub 6}Ni{sub 2}Sn, Er{sub 6}Ni{sub 2}Sn (Ho{sub 6}Ni{sub 2}Ga-type), Ho{sub 2}Ni{sub 2}Sn, Er{sub 2}Ni{sub 2}Sn (Mo{sub 2}FeB{sub 2}-type), HoNi{sub 5}Sn, ErNi{sub 5}Sn (CeCu{sub 4.38}In{sub 1.62}-type), HoNi{sub 1.73}Sn, ErNi{sub 1.72}Sn (YbNi{sub 1.705}Sn-type), HoNiSn, ErNiSn (TiNiSi-type), HoNiSn{sub 2}, ErNiSn{sub 2} (LuNiSn{sub 2}-type), HoNiSn{sub 4}, ErNiSn{sub 4} (LuNiSn{sub 4}-type), and Ho{sub 2}NiSn{sub 6}, Er{sub 2}NiSn{sub 6} (Lu{sub 2}NiSn{sub 6}-type). The interstitial solid solutions HoNi{sub x}Sn{sub 2} (up to 7 at.% Ni) and ErNi{sub x}Sn{sub 2} (up to 5 at.% Ni) based on the RSn{sub 2} (ZrSi{sub 2}-type) binary compounds were found.

  6. Structure and mechanisms underlying ion transport in ternary polymer electrolytes containing ionic liquids.

    Science.gov (United States)

    Mogurampelly, Santosh; Ganesan, Venkat

    2017-02-21

    We use all atom molecular dynamics simulations to investigate the influence of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) ionic liquid on the structure and transport properties of poly(ethylene oxide) (PEO) polymer electrolytes doped with LiPF6 salt. We observe enhanced diffusivities of the Li(+), PF6(-), and BMIM(+) ions with increasing loading of the ionic liquid. Interplay between the different ion-ion and ion-polymer interactions is seen to lead to a destabilization of the Li-PF6 coordination and increase in the strength of association between the Li(+) cations and the polymer backbone. As a consequence, the polymer segmental relaxation times are shown to be only moderately affected by the addition of ionic liquids. The ionic-liquid induced changes in the mobilities of Li(+) ions are seen to be correlated to polymer segmental relaxation times. However, the mobilities of BMIM(+) ions are seen to be more strongly correlated to the BMIM-PF6 ion-pair relaxation times.

  7. Properties of the Band Gaps in 1D Ternary Lossy Photonic Crystal Containing Double-Negative Materials

    National Research Council Canada - National Science Library

    Alireza Aghajamali; Maryam Akbarimoosavi; Mahmood Barati

    2014-01-01

    ... are composed of double-negative and double-positive materials. This study shows that by varying the angle of incidence, the band gaps for TM and TE waves behave differently in both ternary and binary lossy structures...

  8. Crystallization of supercooled liquid antimony: A density functional study

    Science.gov (United States)

    Ropo, M.; Akola, J.; Jones, R. O.

    2017-11-01

    Crystallization of liquid antimony has been studied at 600 K using six density functional/molecular dynamics simulations with up to 882 atoms and three scenarios: one completely disordered sample that did not crystallize even after 570 ps, four with fixed crystalline slab templates, and one with a fixed crystalline seed. Crystallization proceeded layer-by-layer in most cases and was rapid (˜36 m/s) with templates and somewhat slower with the seed. The seed simulation shows an unusual percolation asymmetry where the crystallite grows faster in the direction normal to the zigzag planes. Changes in pair distribution functions, bond angle distributions, ring statistics, nearest-neighbor distances, and cavity volumes were monitored. Diffusion plays a minor role in the process, and the evolution of bond lengths and ring statistics supports the bond-interchange model introduced to explain the rapid crystallization of Sb-rich phase change materials.

  9. Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Kuehnel, Matthias

    2014-02-15

    This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are

  10. Characterization of liquid products from the co-cracking of ternary and quaternary mixture of petroleum vacuum residue, polypropylene, Samla coal and Calotropis Procera

    Energy Technology Data Exchange (ETDEWEB)

    M. Ahmaruzzaman; D.K. Sharma [Indian Institute of Technology Delhi, New Delhi (India). Centre for Energy Studies

    2008-08-15

    The co-cracking of the petroleum vacuum residue (XVR) with polypropylene (PP), Samla coal (SC) and Calotropis procera (CL) has been carried out in a batch reactor under isothermal conditions at atmospheric pressure. The liquids obtained by co-cracking have been characterized by Fourier transform infrared spectroscopy, high performance liquid chromatography, {sup 1}H nuclear magnetic resonance (NMR), {sup 13}C NMR, gel permeation chromatography (GPC), and inductively coupled argon plasma analyses. It was found that the liquid products obtained from the co-cracking of ternary and quaternary mixtures of the petroleum vacuum residue with polypropylene, coal and C. procera contained less than 1 ppm of Ni and V. The HPLC analyses indicates that the liquids obtained from the cracking of ternary mixture of XVR+PP+CL were mainly aliphatic in nature (saturates content 87.4%). NMR analyses showed that the aromatic carbon contents decreased (15.0%) in the liquid products derived from the co-cracking of quaternary mixtures of XVR+PP+SC+CL compared to their theoretical averages (taking the averages of aromatic carbon contents of the liquids from XVR, PP, SC and CL individually). The overall results indicated that there exists a definite interaction of reactive species when XVR, PP, SC and CL were co-cracked together. 27 refs., 5 tabs.

  11. Diffusion-Driven Dissolution or Growth of a Liquid Drop Embedded in a Continuous Phase of Another Liquid via Phase-Field Ternary Mixture Model.

    Science.gov (United States)

    Lamorgese, Andrea; Mauri, Roberto

    2017-11-14

    We simulate the diffusion-driven dissolution or growth of a single-component (resp. two-component) drop embedded in a continuous phase of a binary (resp. single-component) liquid. Our theoretical approach follows a standard diffuse-interface model of partially miscible ternary liquid mixtures, which is based on a regular solution model assumption together with a Flory-Huggins and Cahn-Hilliard representation of the excess and nonlocal components of the Gibbs free energy of mixing. Based on 2D simulation results, we show that for a single-component drop embedded in a continuous phase of a binary liquid (which is highly miscible with either one component of the continuous phase but essentially immiscible with the other) the size of the drop can either shrink to zero or reach a stationary value, depending on whether the global composition of the mixture is within the one-phase region or the unstable range of the phase diagram. On the other hand, for an isolated two-component drop embedded in a continuous phase of a single-component liquid (which is essentially immiscible with either one component of the drop but miscible with the other) the size of the drop can either grow or shrink and, in particular, it will eventually go to zero if the global composition of the mixture is within the one-phase region; otherwise, for system locations in the unstable range the size of the drop tends to a constant value as the composition within the drop reaches its final equilibrium value.

  12. Synthesis, Crystal Structure, Spectroscopic Properties and Potential Biological Activities of Salicylate‒Neocuproine Ternary Copper(II Complexes

    Directory of Open Access Journals (Sweden)

    Lenka Kucková

    2015-01-01

    Full Text Available Mixed ligand copper(II complexes containing derivatives of salicylic acid and heterocyclic ligands with nitrogen donor atoms have been the subject of various studies and reviews. In this paper, synthesis and characterization of the ternary copper(II complexes of neocuproine (2,9-dimethyl-1,10-phenanthroline, Neo and salicylate ligands (Sal are reported. In addition, the crystal structures of ([Cu(H2O(5-Cl-Sal(Neo] (1, [Cu(μ-Sal(Neo]2 (2, Cu2(μ-5-Cl-Sal(5-Cl-HSal2(Neo2]·EtOH (3 were determined. In order to compare structural and biological properties of the prepared complexes, spectroscopic and biological studies were performed. Results of X-ray diffraction show that prepared complexes form three types of crystal structures in a given system: monomeric, dimeric and dinuclear complex. The preliminary study on the DNA cleavage activity has shown that the complexes under study behave as the chemical nucleases in the presence of added hydrogen peroxide with slight differences in the activity (1 > 2 > 3. The complexes 1 and 2 exhibited nuclease activity itself indicating the interaction of complexes with the DNA. It has been proposed that the enhanced destructive effect of the complexes 1 and 2 on the DNA is a result of two possible mechanisms of action: (i the conversion of closed circular DNA (form I to the nicked DNA (form II caused by the copper complex itself and (ii damage of DNA by Reactive Oxygen Species (ROS—products of the interaction of copper with hydrogen peroxide by means of Fenton reaction (hydroxyl radicals. Thus the biological activity of the prepared Cu(II complexes containing derivatives of salicylic acid and phenanthroline molecules is substantiated by two independent mechanisms. While derivatives of salicylic acids in the coordination sphere of copper complexes are responsible for radical-scavenging activity (predominantly towards superoxide radical anion, the presence of chelating ligand 2,9-dimethyl-1,10-phenanthroline

  13. Liquid Crystals for Organic Field-Effect Transistors

    Science.gov (United States)

    O'Neill, Mary; Kelly, Stephen M.

    Columnar, smectic and lamellar polymeric liquid crystals are widely recognized as very promising charge-transporting organic semiconductors due to their ability to spontaneously self-assemble into highly ordered domains in uniform thin films over large areas. The transport properties of smectic and columnar liquid crystals are discussed in Chaps. 2 (10.1007/978-90-481-2873-0_2) and 3 (10.1007/978-90-481-2873-0_3). Here we examine their application to organic field-effect transistors (OFETs): after a short introduction in Sect. 9.1 we introduce the OFET configuration and show how the mobility is measured in Sect. 9.2. Section 9.3 discusses polymeric liquid crystalline semiconductors in OFETs. We review research that shows that annealing of polymers in a fluid mesophase gives a more ordered microcrystalline morphology on cooling than that kinetically determined by solution processing of the thin film. We also demonstrate the benefits of monodomain alignment and show the application of liquid crystals in light-emitting field-effect transistors. Some columnar and smectic phases are highly ordered with short intermolecular separation to give large π-π coupling. We discuss their use in OFETs in Sects. 9.4, and 9.5 respectively. Section 9.6 summarises the conclusions of the chapter.

  14. Mixing effects in the crystallization of supercooled quantum binary liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kühnel, M.; Kalinin, A. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Fernández, J. M.; Tejeda, G.; Moreno, E.; Montero, S. [Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Tramonto, F.; Galli, D. E. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Nava, M. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Grisenti, R. E. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI - Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    2015-08-14

    By means of Raman spectroscopy of liquid microjets, we have investigated the crystallization process of supercooled quantum liquid mixtures composed of parahydrogen (pH{sub 2}) or orthodeuterium (oD{sub 2}) diluted with small amounts of neon. We show that the introduction of the Ne impurities affects the crystallization kinetics in terms of a significant reduction of the measured pH{sub 2} and oD{sub 2} crystal growth rates, similarly to what found in our previous work on supercooled pH{sub 2}-oD{sub 2} liquid mixtures [Kühnel et al., Phys. Rev. B 89, 180201(R) (2014)]. Our experimental results, in combination with path-integral simulations of the supercooled liquid mixtures, suggest in particular a correlation between the measured growth rates and the ratio of the effective particle sizes originating from quantum delocalization effects. We further show that the crystalline structure of the mixtures is also affected to a large extent by the presence of the Ne impurities, which likely initiate the freezing process through the formation of Ne-rich crystallites.

  15. Thermodynamic modeling of ternary and quaternary (liquid + liquid) systems containing water, FeCl3, HCl and diisopropyl ether

    NARCIS (Netherlands)

    Milosevic, M.; Hendriks, I.; Smits, R.E.R.; Schuur, Boelo; de Haan, A.B.

    2013-01-01

    Liquid–liquid extraction using ethers as solvents is a potentially energy saving alternative for the concentration of aqueous ferric chloride solutions. Adequate thermodynamic models that describe the behavior of the resulting quaternary systems (FeCl3, ether, acid and water) are not available in

  16. Determination of solid-liquid interfacial energies in the In-Bi-Sn ternary alloy

    Energy Technology Data Exchange (ETDEWEB)

    Akbulut, S; Ocak, Y [Department of Physics, Institute of Science and Technology, Erciyes University, Kayseri, 38039 (Turkey); Marasli, N; Keslioglu, K [Department of Physics, Faculty of Arts and Sciences, Erciyes University, Kayseri, 38039 (Turkey); Kaya, H [Department of Science Education, Education Faculty, Erciyes University, Kayseri, 38039 (Turkey); Cadirli, E [Department of Physics, Faculty of Arts and Sciences, Nigde University, Nigde (Turkey)], E-mail: marasli@erciyes.edu.tr

    2008-09-07

    The equilibrated grain boundary groove shapes of solid In{sub 2}Bi solution in equilibrium with the In-Bi-Sn eutectic liquid were observed from a quenched sample at 59 {sup 0}C. The Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of the solid In{sub 2}Bi solution have been determined to be (1.42 {+-} 0.07) x 10{sup -7} K m, (49.6 {+-} 5.0) x 10{sup -3} J m{sup -2} and (97.1 {+-} 10.7) x 10{sup -3} J m{sup -2}, respectively, from the observed grain boundary groove shapes. The thermal conductivities of the solid phases for In-21.23 at% Bi-19.04 at% Sn and In-30.5 at% Bi-3 at% Sn alloys and the thermal conductivity ratio of the liquid phase to the solid phase for In-21.23 at% Bi-19.04 at% Sn have also been measured with a radial heat flow apparatus and a Bridgman type growth apparatus, respectively, at their melting temperature.

  17. Colorimetric qualification of shear sensitive liquid crystal coatings

    Science.gov (United States)

    Muratore, Joseph J., Jr.

    1993-01-01

    The work that has been done to date on the Shear Sensitive Liquid Crystal Project demonstrated that cholesteric liquid crystal coatings respond to both the direction and magnitude of a shearing force. The response of the coating is to selectively scatter incident white light into a spectrum of colors. Discernible color changes at a fixed angle of observation and illumination are the result of an applied shear stress. The intention was to be able to convert these observable color patterns from a flow visualization technique into a quantitative tool. One of the earlier intentions was to be able to use liquid crystals in dynamic flow fields. This was assumed possible because liquid crystals had made it possible to visualize transients in surface shear forces. Although the transients were visualized by color changes to an order one micro second, the time response of a coating to align to a shearing force is dependent on the magnitude of the change between its initial and final states. Unfortunately, the response is not instantaneous. It is for this reason any future attempt at quantifying the magnitude and directions of a shearing force are limited to surface shear stress vector fields in three dimensional steady state flows. This limitation does not significantly detract from the utility of liquid crystal coatings. The measurement of skin friction in the study of transition on wings, prediction of drag forces, performance assessment, and the investigation of boundary layer behavior is of great importance in aerodynamics. There exist numerous examples of techniques for the measurement of surface shear stress. Most techniques require arduous calibrations and necessitate extensive preparation of the receiving surfaces. However, the main draw back of instruments such as Preston tubes, hot films, buried wire gages, and floating element balances is that they only provide a point measurement. The advantages of capturing global shear data would be appreciable when compared

  18. Crystal growth of sulfide materials from alkali polysulfide liquids

    Science.gov (United States)

    White, W. B.

    1979-01-01

    The fluids experiment system was designed for low temperature solution growth, nominally aqueous solution growth. The alkali polysulfides, compositions in the systems Na2S-S and K2S-S form liquids in the temperature range of 190 C to 400 C. These can be used as solvents for other important classes of materials such as transition metal and other sulfides which are not soluble in aqueous media. Among these materials are luminescent and electroluminescent crystals whose physical properties are sensitive functions of crystal perfection and which could, therefore, serve as test materials for perfection improvement under microgravity conditions.

  19. Electrically tunable zero dispersion wavelengths in photonic crystal fibers filled with a dual frequency addressable liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wahle, Markus, E-mail: markus.wahle@uni-paderborn.de; Kitzerow, Heinz-Siegfried [Department of Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany and Center for Optoelectronics and Photonics Paderborn (CeOPP), Warburger Str. 100, 33098 Paderborn (Germany)

    2015-11-16

    We present a liquid crystal (LC) infiltrated photonic crystal fiber, which enables the electrical tuning of the position of zero dispersion wavelengths (ZDWs). A dual frequency addressable liquid crystal is aligned perpendicular on the inclusion walls of a photonic crystal fiber, which results in an escaped radial director field. The orientation of the LC is controlled by applying an external electric field. Due to the high index of the liquid crystal the fiber guides light by the photonic band gap effect. Multiple ZDWs exist in the visible and near infrared. The positions of the ZDWs can be either blue or red shifted depending on the frequency of the applied voltage.

  20. Tunable and rotatable polarization controller using photonic crystal fiber filled with liquid crystal

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2010-01-01

    We design and fabricate a compact tunable and rotatable polarization controller using liquid crystal photonic band gap fibers. The electrically and thermally induced phase shift in the Poincaré sphere and corresponding birefringence change are measured. The direction of the electric field...

  1. Switching of liquid crystal devices between reflective and transmissive modes

    Science.gov (United States)

    Lin, Hui-Chi; Wang, Chih-Hung

    Transflective liquid crystal displays (LCD) are commonly known that each pixel is divided into reflective (R) and transmissive (T) subpixels. The R mode uses ambient light, while the T mode utilizes a backlight to display images. However, the division of the pixel decreases the light efficiency and the resolution. This study demonstrates a gelator-doped liquid crystal (LC) devices, that is switchable between R and T modes, without sub-pixel division. The R and T modes are designed to have bend configurations with phase retardation of π/2 and π, respectively. The phase retardation of a LC device can be varied and fixed by the thermoreversible association and dissociation of the gelator molecules. It is believed that the proposed device is a potential candidate for portable information systems.

  2. High-speed imaging polarimetry using liquid crystal modulators

    Directory of Open Access Journals (Sweden)

    Ambs P.

    2010-06-01

    Full Text Available This paper deals with dynamic polarimetric imaging techniques. The basics of modern polarimetry have been known for one and a half century, but no practical high-speed implementation providing the full polarization information is currently available. Various methods are reviewed which prove to be a trade-off between the complexity of the optical set-up and the amount of polarimetric information they provide (ie the number of components of the Stokes vector. Techniques using liquid crystal devices, incepted in the late 1990's, are emphasized. Optical set-ups we implemented are presented. We particularly focus on high-speed techniques (i.e. faster than 200 Hz using ferroelectric liquid crystal devices.

  3. Subwavelength coupling strengthened optical amplification in nematic liquid crystal cells

    Science.gov (United States)

    Zhao, Hua; Xue, Tingyu; Su, Hang; Wang, Yingce; Zhang, Jingwen

    2017-09-01

    We observed strikingly different first reflection dynamics of two counter-propagating laser beams passing through a wedge-shaped C60-doped liquid crystal cell sandwiched between two ZnSe-coated ITO glass plates without applied electric field, suggesting a strong subwavelength energy coupling between light beams. Exponential gain coefficient as high as 10 574 cm-1 was obtained from the 1.1 μm-thick portion of the cell under applied voltage U0 = 3.0 V, consisting with the subwavelength coupling picture. Surface plasmon polariton (SPP) supporting layer is identified by considering dipolar properties of liquid crystal molecules that are well aligned. The specific features in energy coupling dynamics and 2D diffraction patterns perceived suggest that SPP mediated coupling is responsible for all the findings.

  4. Liquid crystal polymer substrate based wideband tapered step antenna

    Directory of Open Access Journals (Sweden)

    Boddapati Taraka Phani MADHAV

    2015-05-01

    Full Text Available Performance study of wideband tapered step antenna on liquid crystal polymer substrate material is presented. Bandwidth enhancement is achieved by adding step serrated ground on the front side of the model along with the radiating patch. The radiating patch seems to be the intersection of two half circles connected back to back. The lower half circle radius is more than upper half circle radius. Wideband tapered step antenna is designed on the liquid crystal polymer substrate (Ultralam 3850, εr = 2.9 with dimensions of 20×20×0.5 mm. Coplanar waveguide feeding is used in this model with feed line width of 2.6 mm and gap between feed line to ground plane of 0.5 mm.

  5. Proton irradiation of liquid crystal based adaptive optical devices

    Energy Technology Data Exchange (ETDEWEB)

    Buis, E.J., E-mail: ernst-jan.buis@tno.nl [cosine Science and Computing BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands); Berkhout, G.C.G. [cosine Science and Computing BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands); Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Love, G.D.; Kirby, A.K.; Taylor, J.M. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Hannemann, S.; Collon, M.J. [cosine Research BV, Niels Bohrweg 11, 2333 CA Leiden (Netherlands)

    2012-01-01

    To assess its radiation hardness, a liquid crystal based adaptive optical element has been irradiated using a 60 MeV proton beam. The device with the functionality of an optical beam steerer was characterised before, during and after the irradiation. A systematic set of measurements on the transmission and beam deflection angles was carried out. The measurements showed that the transmission decreased only marginally and that its optical performance degraded only after a very high proton fluence (10{sup 10}p/cm{sup 2}). The device showed complete annealing in the functionality as a beam steerer, which leads to the conclusion that the liquid crystal technology for optical devices is not vulnerable to proton irradiation as expected in space.

  6. Skin friction measurement with partially exposed polymer dispersed liquid crystals

    Science.gov (United States)

    Parmar, D. S.; Holmes, H. K.

    1993-01-01

    Partially exposed polymer dispersed liquid crystal thin film (10-25 microns) deposited on a flat glass substrate has been used for the first time to measure skin friction. Utilizing the shear-stress-induced director reorientation in the partially exposed liquid-crystal droplets, optical transmission under crossed polarization has been measured as a function of the air flow differential pressure. Direct measurement of the skin friction with a skin friction drag balance, under the same aerodynamic conditions, lets us correlate the skin friction with optical transmission. This provides a unique technique for the direct measurement of skin friction from the transmitted light intensity. The results are in excellent agreement with the model suggested in this paper.

  7. Study of the properties of liquid crystals modified by nanoparticles

    Science.gov (United States)

    Kalashnikov, S. V.; Romanov, N. A.; Nomoev, A. V.

    2016-03-01

    The dielectric anisotropy and the response time of polymer-dispersed liquid-crystal films mixed with various nanoparticles were measured. The different types of nanoparticles used included metallic, dielectric, and biphasic core-shell or Janus type nanoparticles. Two methods were used for the determination of the dielectric anisotropy: a bridge method and a current-voltage method. The dipole moments of the nanoparticles were measured by the method of diluted solutions (Debye method). It was shown that the dielectric anisotropy plays a crucial role in the electro-optical properties of modified liquid crystals which in turn depend on the dipole moment and thus on the physical nature of the introduced nanoparticles.

  8. Self-assembly of nematic liquid crystal elastomer filaments

    Science.gov (United States)

    Wei, Wei-Shao; Xia, Yu; Yang, Shu; Yodh, A. G.

    In this work we investigate the self-assembly of nematic liquid crystal polymer (NLCP) filaments and their corresponding cross-linked elastomer structures. Specifically, by fine-tuning surfactant concentration, prepolymer chain length, and temperature within a background aqueous phase we can generate filaments composed of oligomerized LC monomers. Filaments with narrowly dispersed diameters ranging from one hundred nanometers to a few micrometers can be obtained. Using polarization optical microscopy, we show that the nematic LCs within the filaments have an escaped radial structure. After photo-cross-linking, nematic liquid crystal elastomer filaments are obtained with well-maintained directors and smooth surface structure. Since these materials are elastomers, the size and mechanical and optical response of the filaments can be ''tuned'' near the nematic to isotropic phase transition temperature. This work is supported by NSF DMR16-07378, PENN MRSEC Grant DMR11-20901, and NASA Grant NNX08AO0G.

  9. A liquid crystal biosensor for specific detection of antigens

    Directory of Open Access Journals (Sweden)

    Piotr Popov

    2016-05-01

    Full Text Available Following the principle of the enzyme-linked immunosorbent assay (ELISA pathogen detection method, we demonstrate specific sensing of goat Immunoglobulin G (IgG by a nematic liquid crystal material. Sensing occurs via the visually-striking realignment of a pre-fabricated liquid crystal film, suspended in grids and coated with biotinylated lipids followed by biotinylated anti-goat IgG. Realignment occurs when the targeted goat IgG is added to the cell, but not when rat or rabbit serum IgG is added to the same surface. In principle, this method can be generalized to provide an inexpensive, fast and sensitive prefabricated sensor for any pathogen.

  10. Domain Structures in Nematic Liquid Crystals on a Polycarbonate Surface

    Directory of Open Access Journals (Sweden)

    Vasily F. Shabanov

    2013-08-01

    Full Text Available Alignment of nematic liquid crystals on polycarbonate films obtained with the use of solvents with different solvations is studied. Domain structures occurring during the growth on the polymer surface against the background of the initial thread-like or schlieren texture are demonstrated. It is established by optical methods that the domains are stable formations visualizing the polymer surface structures. In nematic droplets, the temperature-induced transition from the domain structure with two extinction bands to the structure with four bands is observed. This transition is shown to be caused by reorientation of the nematic director in the liquid crystal volume from the planar alignment to the homeotropic state with the pronounced radial configuration of nematic molecules on the surface. The observed textures are compared with different combinations of the volume LC orientations and the radial distribution of the director field and the disclination lines at the polycarbonate surface.

  11. Infiltration liquid crystal in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Bang, Ole

    2009-01-01

    POF is butt-coupled to a conventional single mode fiber (SMF) with the broadband light from a supercontinuum source. It is clear to see the colour of the guided modes is red, since some wavelengths are attenuated by the material loss of PMMA in visible region. A positive dielectric anisotropy liquid crystal E......7 is then infiltrated into about 6 cm of the length of mPOF by using capillary forces with the duration of 45 minutes. The transmission spectrum is measured by an optical spectrum analyzer with 1 nm resolution, and normalized to that of the unfilled fiber as shown by the solid line. The difference......Here, we firstly demonstrate the photonic bandgap effect with PMMA mPOF by filling the air holes with liquid crystal, and subsequently change the light guidance mechanism from index guiding to bandgap guiding. The triangular structure PMMA mPOF used in the experiment is fabricated. A 60 cm length m...

  12. Polymer-Dispersed Liquid Crystal Films For Light Control Applications

    Science.gov (United States)

    Montgomery, G. P.

    1989-07-01

    Polymer-dispersed liquid crystal (PDLC) films, comprised of liquid crystal microdroplets dispersed in polymer matrices, are attractive for a variety of indoor and outdoor light control applications since they can be switched electrically from a light-scattering off-state to a transparent on-state. This paper reviews the electro-optic properties of PDLC films which govern their performance in such diverse applications as electronic information displays, signs, room dividers, and solar energy control in buildings and automobiles. Factors governing the operating temperature range of PDLC films will be identified and temperature-dependent transmittance and response-time characteristics of these films will be presented. Spectral transmittance characteristics will be discussed and used to determine contrast ratios of PDLC films. Dual frequency addressing of PDLC films will be demonstrated and shown to be a viable technique for increasing contrast ratio of PDLC displays. Solar attenuation properties of PDLC films will be reviewed.

  13. Optical switching of near infrared light transmission in metamaterial-liquid crystal cell structure.

    Science.gov (United States)

    Kang, Boyoung; Woo, J H; Choi, E; Lee, Hyun-Hee; Kim, E S; Kim, J; Hwang, Tae-Jong; Park, Young-Soon; Kim, D H; Wu, J W

    2010-08-02

    A metamaterial-liquid crystal cell structure is fabricated with the metamaterial as one of the liquid crystal alignment layers. Nano-sized double-split ring resonator in the metamaterial accommodates two distinct resonances in the near infrared regime. By adopting an azo-nematic liquid crystal in a twisted nematic liquid crystal cell structure, a photo-isomerization process is utilized to achieve an optical switching of light transmissions between two resonances. A single device of the metamaterial-liquid crystal cell structure has a potential application in the photonic switching in optical fiber telecommunications.

  14. Polymerization in Liquid Crystal Medium: Preparation of Polythiophene Derivatives Bearing a Bulky Pyrimidine Substituent

    Directory of Open Access Journals (Sweden)

    Hiromasa Goto

    2010-10-01

    Full Text Available We carried out polycondensation of monomers bearing a bulky pyrimidine substituent in a liquid crystal solvent. The resultant polymers formed nematic liquid crystals. The polymers prepared in liquid crystals had higher coplanarity than the polymers prepared in toluene. This can be due to the fact that the ordered medium of the liquid crystal produces an aggregated structure with well-developed π-stacking between the main chains. The present results demonstrated that polymerization of bulky monomers is possible in liquid crystal solvents.

  15. Induced orientational behavior of liquid crystal polymer by carbon fibers

    Science.gov (United States)

    Chung, T. S.; Gurion, Z.; Stamatoff, J. B.

    1985-01-01

    Experimental results are presented that show that the structure of carbon fibers induces molecular orientation of liquid crystal polymers. X-ray diffraction data are used to demonstrate final collinearity of the polymer molecular axis and carbon fiber axis independent of fabrication approaches or prefabrication orientation of the polymer relative to the carbon fiber direction. The final degree of polymer molecular orientation approximately equals the degree of carbon basal plane orientation within the carbon fiber.

  16. Novel addressing scheme for passive antiferroelectric liquid crystal displays

    Science.gov (United States)

    Quintana, Xabier; Castillo, P. L.; Oton, Jose; Bennis, N.; Lara, A.; Urruchi, V.; Dabrowski, Roman S.

    2004-09-01

    In this work, the use of antiferroelectric liquid crystals for high-end passive displays has been explored. Antiferroelectric gray levels arise from a double symmetric hysteresis loop that can be stabilized by a constant holding voltage. This driving scheme is passive multiplexing compatible, but limitations appear when the multiplexing rate increases. We have developed new waveforms and driving schemes for high multiplexing level at video rate. The problem of accumulated voltage on bias level arising from data voltages is tackled as well.

  17. Single Molecule Studies on Dynamics in Liquid Crystals

    OpenAIRE

    Daniela Täuber; Christian von Borczyskowski

    2013-01-01

    Single molecule (SM) methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC). Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization...

  18. Localized soft elasticity in liquid crystal elastomers (POSTPRINT)

    Science.gov (United States)

    2016-02-23

    AFRL-RX-WP-JA-2016-0280 LOCALIZED SOFT ELASTICITY IN LIQUID CRYSTAL ELASTOMER (POSTPRINT) Taylor H. Ware, Andreas F. Shick, and...should be aware that notwithstanding any other provision of law , no person shall be subject to any penalty for failing to comply with a collection of...MM-YY) 2. REPORT TYPE 3. DATES COVERED (From - To) 11 August 2015 Interim 31 January 2014 – 11 July 2015 4. TITLE AND SUBTITLE LOCALIZED SOFT

  19. Supercoiled DNA; plectonemic structure and liquid crystal formation

    CERN Document Server

    Maarel, J R C; Jesse, W; Backendorf, C; Egelhaaf, S U; Lapp, A

    2003-01-01

    We have investigated the phase behaviour of pUC18 plasmid solutions with phase separation experiments and polarized light microscopy. Furthermore, the configuration of the superhelix is monitored with small-angle neutron scattering. The phase diagram is interpreted with liquid crystal theory including the effects of charge, orientation entropy, excluded volume, as well as the elastic, entropic and electrostatic contributions to the molecular free energy.

  20. Liquid Crystals Viscous and Elastic Properties in Theory and Applications

    CERN Document Server

    Pasechnik, Sergey V; Shmeliova, Dina V

    2009-01-01

    Covering numerous practical applications as yet not covered in any single source of information, this monograph discusses the importance of viscous and elastic properties for applications in both display and non-display technologies. The very well-known authors are major players in this field of research and pay special attention here to the use of liquid crystals in fiber optic devices as applied in telecommunication circuits.

  1. Polymer-dispersed liquid-crystal voltage sensor.

    Science.gov (United States)

    Scherschener, Elizabeth; Perciante, César D; Dalchiele, Enrique A; Frins, Erna M; Korn, Matthias; Ferrari, José A

    2006-05-20

    We present a novel electric-field and voltage sensor based on the electro-optical properties of polymer-dispersed liquid-crystals (PDLCs). In principle, the transmittance of PDLCs is a nonlinear function of the applied electrical field. To measure an AC field we superposed to it a known DC field. This allowed us to achieve linearization of the PDLC response and to measure transmittance changes independently of the light-intensity level variations. Validation experiments are presented.

  2. Holographic polymer dispersed liquid crystal enhanced by introducing urethane trimethacrylate.

    Science.gov (United States)

    Nataj, Nahid Hosein; Mohajerani, Ezeddin; Jashnsaz, Hossein; Jannesari, Ali

    2012-02-20

    This work characterizes holographic polymer dispersed liquid crystals (HPDLC) composite material based on a new monomer, urethane trimethacrylate, by fabricating switchable diffraction grating. The highest diffraction efficiency achieved was 90.3%. Details of the fabrication and preliminary results of electro-optical switching of the HPDLC diffraction gratings are presented and discussed based on the functionality of the monomer. These experimental results are explained by means of morphological scanning electron microscopy analyses. © 2012 Optical Society of America

  3. Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells

    OpenAIRE

    VIJ, JAGDISH; SONG, JANG-KUN

    2008-01-01

    PUBLISHED Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells controlled by surface anchoring of the alignment layers is investigated for different conditions of alignment on the two opposite surfaces. We show that the critical field Ec, where the speed of the solitary wave becomes zero, is finite for asymmetric alignment on two surfaces. We also show that the polar anchoring energy difference (Deltawp) between the alignment layers can be calculated by measur...

  4. Low-Absorption Liquid Crystals for Infrared Beam Steering

    Science.gov (United States)

    2014-10-17

    SEEOR) is its relatively long optical beam path. In the VIS and NIR spectral regions, most liquid crystals have negligible absorption so that the...absorption; v.=variable intensity) [B. D. Mistry, ^ Handbook of Spectroscopic Data: Chemistry-UV, IR, PMR, CNMR and Mass Spectroscopy , Oxford, 2009...director was oriented at 45° with respect to the polarizer transmission axis. A linearly polarized He-Ne laser (>^=633nm), a tunable Argon-ion laser

  5. Polarization field effects at liquid-crystal-droplet-polymer interfaces.

    Science.gov (United States)

    Boussoualem, Mourad; Ismaili, Mimoun; Lamonier, Jean-François; Buisine, Jean-Marc; Roussel, Frédérick

    2006-04-01

    The influence of confinement (droplet size) and liquid crystal orientational order (smectic-A and nematic) on the interfacial polarization field effects [Maxwell-Wagner-Sillars (MWS) effect] existing in liquid-crystal-droplets-polymer systems is investigated by broadband dielectric spectroscopy and a forward transmittance measurement technique. A relaxation process observed in the low frequency domain of the dielectric spectrum has been associated with a MWS effect for both micron-size and submicron-size droplets. Using electro-optical measurements and numerical simulations of the field inside droplets, it is shown that a depolarization field takes place in the same frequency range as that determined by dielectric spectroscopy. Differential scanning calorimetry measurements allowed to estimate the phase-separated liquid crystal [4,4'-octylcyanobiphenyl (8CB)] fraction, which was found in the range of 55% for both micron-size and submicron-size droplets. X-ray diffraction experiments showed that smectic 8CB confined to micron-size cavities adopt bulklike properties, i.e., a partial bilayer structure, whereas in submicron-size droplets the layer spacing of the smectic phase is increased due to the strong bending deformations induced by the high curvature of the cavity walls.

  6. IR Sensor Synchronizing Active Shutter Glasses for 3D HDTV with Flexible Liquid Crystal Lenses

    Directory of Open Access Journals (Sweden)

    Jeong In Han

    2013-12-01

    Full Text Available IR sensor synchronizing active shutter glasses for three-dimensional high definition television (3D HDTV were developed using a flexible liquid crystal (FLC lens. The FLC lens was made on a polycarbonate (PC substrate using conventional liquid crystal display (LCD processes. The flexible liquid crystal lens displayed a maximum transmission of 32% and total response time of 2.56 ms. The transmittance, the contrast ratio and the response time of the flexible liquid crystal lens were superior to those of glass liquid crystal lenses. Microcontroller unit and drivers were developed as part of a reception module with power supply for the IR sensor synchronizing active shutter glasses with the flexible liquid crystal lens prototypes. IR sensor synchronizing active shutter glasses for 3D HDTV with flexible liquid crystal lenses produced excellent 3D images viewing characteristics.

  7. Multiresponsive self-assembled liquid crystals with azobenzene groups.

    Science.gov (United States)

    Xu, Miao; Chen, Liqin; Zhou, Yifeng; Yi, Tao; Li, Fuyou; Huang, Chunhui

    2008-10-15

    An optical and electric field-responsive self-assembled complex containing nitril azobenzene groups and 1,3,5-triazine-2,4-diamine was obtained and characterized. Both the azobenzene precursor and the complex form a liquid-crystalline phase in a certain temperature range. The transition temperature from crystalline phase to liquid-crystalline mesophase was obviously decreased in the complex by the self-assembling. The self-assembled liquid crystals revealed good response to both stimuli of light irradiation and electric field, and the induced molecular orientation could be held even after the removal of the stimuli. The structural and mechanical investigation proved that the formation of hydrogen bonds and assembly-induced molecular dipolar change contributed to the multiresponding action. This kind of self-assembled complex thus has potential applications in imaging and data storage.

  8. Photo-Induced Phase Transitions to Liquid Crystal Phases: Influence of the Chain Length from C8E4 to C14E4

    Directory of Open Access Journals (Sweden)

    Simone Techert

    2009-09-01

    Full Text Available Photo-induced phase transitions are characterized by the transformation from phase A to phase B through the absorption of photons. We have investigated the mechanism of the photo-induced phase transitions of four different ternary systems CiE4/alkane (i with n = 8, 10, 12, 14; cyclohexane/H2O. We were interested in understanding the effect of chain length increase on the dynamics of transformation from the microemulsion phase to the liquid crystal phase. Applying light pump (pulse/x-ray probe (pulse techniques, we could demonstrate that entropy and diffusion control are the driving forces for the kind of phase transition investigated.

  9. A study of waste liquid crystal display generation in mainland China.

    Science.gov (United States)

    Liu, Zhifeng; Xu, Zeying; Huang, Haihong; Li, Bingbing

    2016-01-01

    The generation of liquid crystal display waste is becoming a serious social problem. Predicting liquid crystal display waste status is the foundation for establishing a recycling network; however, the difficulty in predicting liquid crystal display waste quantity lies in data mining. In order to determine the quantity and the distribution of liquid crystal display waste in China, the four top-selling liquid crystal display products (liquid crystal display TVs, desktop PCs, notebook PCs, and mobile phones) were selected as study objects. Then, the extended logistic model and market supply A method was used to predict the quantity of liquid crystal display waste products. Moreover, the distribution of liquid crystal display waste products in different regions was evaluated by examining the consumption levels of household equipment. The results revealed that the quantity of waste liquid crystal displays would increase rapidly in the next decade. In particular, the predicted quantity of waste liquid crystal displays would rise to approximately 4.262 × 10(9) pieces in 2020, and the total display area (i.e. the surface area of liquid crystal display panels) of waste liquid crystal displays would reach 5.539 × 10(7) m(2). The prediction on the display area of waste liquid crystal display TVs showed that it would account for 71.5% of the total display area by 2020. Meanwhile, the quantity of waste mobile phones would significantly grow, increasing 5.8 times from 2012 to 2020. In terms of distribution, Guangdong is the top waste liquid crystal display-generating province in China, followed by Jiangsu, Shandong, Henan, Zhejiang, and Sichuan. Considering its regional characteristics, Guangdong has been proposed to be the most important location of the recycling network. © The Author(s) 2015.

  10. Influence of temperature on the (liquid + liquid) equilibria of {l_brace}3-methyl pentane + cyclopentane + methanol{r_brace} ternary system at T = (293.15, 297.15, and 299.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Gramajo de Doz, Monica B. [Departamento de Fisica, Facultad de Ciencias Exactas y Tecnologia, Universidad Nacional de Tucuman, Avenida Independencia 1800, 4000 Tucuman (Argentina)], E-mail: mgramajo@herrera.unt.edu.ar; Cases, Alicia M.; Bonatti, Carlos M.; Solimo, Horacio N. [Departamento de Fisica, Facultad de Ciencias Exactas y Tecnologia, Universidad Nacional de Tucuman, Avenida Independencia 1800, 4000 Tucuman (Argentina)

    2009-11-15

    In order to show the influence of temperature on the (liquid + liquid) equilibria (LLE) of the {l_brace}3-methyl pentane (1) + cyclopentane (2) + methanol (3){r_brace} ternary system, equilibrium results at T = (293.15, 297.15, and 299.15) K are reported. The effect of the temperature on the (liquid + liquid) equilibrium is determined and discussed. Experimental results show that this ternary system is completely homogeneous beyond T = 300 K. All chemicals were quantified by gas chromatography using a thermal conductivity detector. The tie line results were satisfactorily correlated by the Othmer and Tobias method, and the plait point coordinates for the three temperatures were estimated. Experimental values for the ternary system are compared with values calculated by the NRTL and UNIQUAC equations, and predicted by means of the UNIFAC group contribution method. It is found that the UNIQUAC and NRTL models provide similar good correlations of the solubility curve at these three temperatures. Finally, the UNIFAC model predicts binodal band type curves in the range of temperatures studied here, similar to those observed for systems classified by Treybal as type 2, instead of type 1 as experimentally observed. Distribution coefficients were also analysed through distribution curves.

  11. Liquid Crystals of Dendron-Like Pt Complexes Processable Into Nanofilms Dendrimers. Phase 2. Cholesteric Liquid Crystal Glass Platinum Acetylides

    Science.gov (United States)

    2014-08-01

    Std. Z39.18 Final Report Liquid Crystals of Dendron-Like Pt Complexes Processable Into Nanofilms. Dendrimers Eduardo Arias...to pack and also the presence of a polar group. Figure 4. Summary of phase behavior. DENDRIMERS New Denrimers. The synthesis...purification and some spectral characteristics of the new dendrimers shown in Fig 5 were reported in AFOSR FA9550-11-1-0169, May, 2013. Further

  12. Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

    Energy Technology Data Exchange (ETDEWEB)

    Leaw, W.L. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Mamat, C.R., E-mail: che@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Jalil, A.A. [Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Univerisiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Bidin, N. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia)

    2016-12-01

    Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen.

  13. Bond orientational order in liquids: Towards a unified description of water-like anomalies, liquid-liquid transition, glass transition, and crystallization: Bond orientational order in liquids.

    Science.gov (United States)

    Tanaka, Hajime

    2012-10-01

    There are at least three fundamental states of matter, depending upon temperature and pressure: gas, liquid, and solid (crystal). These states are separated by first-order phase transitions between them. In both gas and liquid phases a complete translational and rotational symmetry exist, whereas in a solid phase both symmetries are broken. In intermediate phases between liquid and solid, which include liquid crystal and plastic crystal phases, only one of the two symmetries is preserved. Among the fundamental states of matter, the liquid state is the most poorly understood. We argue that it is crucial for a better understanding of liquids to recognize that a liquid generally has the tendency to have a local structural order and its presence is intrinsic and universal to any liquid. Such structural ordering is a consequence of many-body correlations, more specifically, bond angle correlations, which we believe are crucial for the description of the liquid state. We show that this physical picture may naturally explain difficult unsolved problems associated with the liquid state, such as anomalies of water-type liquids (water, Si, Ge, ...), liquid-liquid transition, liquid-glass transition, crystallization and quasicrystal formation, in a unified manner. In other words, we need a new order parameter representing a low local free-energy configuration, which is a bond orientational order parameter in many cases, in addition to a density order parameter for the physical description of these phenomena. Here we review our two-order-parameter model of liquid and consider how transient local structural ordering is linked to all of the above-mentioned phenomena. The relationship between these phenomena is also discussed.

  14. Liquid crystal-enabled electrophoresis and electro-osmosis

    Science.gov (United States)

    Lavrentovich, Oleg D.

    This work presents a comparative review of electrokinetic effects in isotropic and anisotropic (liquid crystalline) electrolytes. A special emphasis is placed on nonlinear electrokinetics with ow velocities growing as the square of the applied electric field. This phenomenon allows one to drive steady motion of particles and uids with an alternating-current electric field. In isotropic electrolytes, spatial separation of charges that leads to nonlinear electrokinetics is achieved through the properties of the solid component (typically a metal). If the electrolyte is a liquid crystal (LC), its anisotropic properties enable separation of charges in the presence of orientational distortions and under the action of an electric field. LC anisotropy leads to electrically-driven motion of colloidal particles (liquid crystal-enabled electrophoresis, LCEP) and of the LC itself (liquid crystal-enabled electro-osmosis, LCEO). The induced charge is proportional to the applied field, director gradients, anisotropy of conductivity, and anisotropy of permittivity. The electric field acts on the space separated charges to drive the electro-osmotic ows. If the director deformations lack mirror symmetry, the LC enables electrophoresis of free particles and electro-osmotic pumping. The advantage of LCenabled electrokinetics (LCEK) is that its mechanism lifts many restrictions imposed on the properties of the solid counterpart. For example, LCEP can transport particles even if these particles are deprived of any surface charges; the particles can even be a uid immiscible with a LC or a gas bubble. In a similar fashion, LCEO can drive ows even if there are no oating electrodes. Ionic currents in LCs which have been traditionally considered an undesirable feature in displays offer a broad platform for versatile applications in electrokinetics of particles and uids, micropumping and mixing, and lab-on-a-chip analysis...

  15. Molecular thermodynamic analysis for assessing the relationship between reentrant swelling behavior and ternary liquid-liquid equilibrium for poly(N-isopropylacrylamide) nanometer-sized gel particles in a water-tetrahydrofuran cosolvent system.

    Science.gov (United States)

    Jung, Sang Chul; Bae, Young Chan

    2012-02-23

    The influence of phase separation on swelling behavior was investigated based on the thermodynamic framework of reswelling phenomena. The cloud-point for a ternary system of water(1)-tetrahydrofuran (THF)(2)-poly(N-isopropylacrylamide)(3) was examined by thermo-optical analysis (TOA). Nanometer-sized N-isopropylacrylamide (NIPA) gel particles were prepared by precipitation polymerization, and their swelling behaviors were determined using photon correlation spectroscopy (PCS). NIPA gel particles underwent reswelling when the ratio of water to THF was varied. First, the modified double lattice model (MDL) was employed to determine ternary interaction energy parameters for the liquid-liquid equilibrium (LLE) of linear poly-NIPA in a water-THF cosolvent system. The reentrant swelling equilibria of the NIPA gel in the water-THF system were then calculated using the interaction energy parameters. © 2012 American Chemical Society

  16. Electrically Rotatable Polarizer Using One-Dimensional Photonic Crystal with a Nematic Liquid Crystal Defect Layer

    Directory of Open Access Journals (Sweden)

    Ryotaro Ozaki

    2015-09-01

    Full Text Available Polarization characteristics of defect mode peaks in a one-dimensional (1D photonic crystal (PC with a nematic liquid crystal (NLC defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD simulation.

  17. Nuclear magnetic resonance study of epoxy- based polymer-dispersed liquid crystal droplets

    CERN Document Server

    Han, J W

    1998-01-01

    In this work, polymer-dispersed liquid crystals (PDLC) samples were prepared and studied by nuclear magnetic resonance. Proton NMR spectra and spin-lattice relaxations of 4-cyano-4'-pentylbiphenyl(5CB) and p-methoxybenzylidene-p-n-butylaniline (MBBA) liquid crystals confined in microdroplets were measured. The experimental results were compared with those of the liquid crystals in the pores of silica-gels and with those of the mixing components. The experimental results indicated that the nematic ordering in the microdroplets differed markedly from that observed in bulk nematic crystals. In addition, we examined spin-lattice relaxation mechanisms. The proton spin-lattice relaxation mechanisms in bulk nematic liquid crystals are well established. However, when nematic liquid crystals are confined in microdroplets, the relaxation mechanisms are expected to be affected. We examined possible relaxation mechanisms to explain the observed increase in the spin-lattice relaxation rate of liquid crystals confined in m...

  18. Ternary fission

    Indian Academy of Sciences (India)

    2015-08-05

    Aug 5, 2015 ... We present the ternary fission of 252Cf and 236U within a three-cluster model as well as in a level density approach. The competition between collinear and equatorial geometry is studied by calculating the ternary fragmentation potential as a function of the angle between the lines joining the stationary ...

  19. Ternary fission

    Indian Academy of Sciences (India)

    Recently, we have studied the various aspects associated with the ternary fission process. A model, called the three-cluster model (TCM) [1–6] has been put forth. This accounts for the energy minimization of all possible ternary breakups of a heavy radioactive nucleus. Further, within the TCM we have analysed the ...

  20. Soap, science, and flat-screen TVs a history of liquid crystals

    CERN Document Server

    Dunmur, David

    2011-01-01

    The terms 'liquid crystal' or 'liquid crystal display' (LCD) are well-known in the context of flat-screen televisions, but the properties and history of liquid crystals are little understood. This book tells the story of liquid crystals, from their controversial discovery at the end of the nineteenth century, to their eventual acceptance as another state of matter to rank alongside gases, liquids and solids. As their story unfolds, the scientists involved and their works are put into illuminating broader socio-political contexts. In recent years, liquid crystals have had a major impact on the display industry, culminating in the now widely available flat-screen televisions; this development is described in detail over three chapters, and the basic science behind it is explained in simple terms accessible to a general reader. New applications of liquid crystals in materials, bio-systems, medicine and technology are also explained.

  1. Liquid Crystal Mediated Nano-assembled Gold Micro-shells

    Science.gov (United States)

    Quint, Makiko; Sarang, Som; Quint, David; Huang, Kerwyn; Gopinathan, Ajay; Hirst, Linda; Ghosh, Sayantani

    We have created 3D nano-assenbled micro-shell by using thermotropic liquid crystal (LC), 4-Cyano-4'-pentylbiphenyl (5CB), doped with mesogen-functionalized gold nanoparticles (AuNPs). The assembly process is driven by the isotropic-nematic phase transition dynamics. We uniformly disperse the functionalized AuNPs into isotropic liquid crystal matrix and the mixture is cooled from the isotropic to the nematic phase. During the phase transition, the separation of LC-AuNP rich isotropic and ordered 5CB rich domains cause the functionalized AuNPs to move into the shrinking isotropic regions. The mesogenic ligands are locally crystalized during this process, which leads to the formation of a spherical shell with a densely packed wall of AuNPs. These micro-shells are capable of encapsulating fluorescence dye without visible leakages for several months. Additionally, they demonstrate strong localized surface plasmon resonance, which leads to localized heating on optical excitation. This photothermal effect disrupts the structure, releasing contents within seconds. Our results exhibiting the capture and optically regulated release of encapsulated substances is a novel platform that combines drug-delivery and photothermal therapy in one versatile and multifunctional unit. This work is supported by the NSF Grants No. DMR-1056860, ECC-1227034, and a University of California Merced Faculty Mentor Fellowship.

  2. Electrically and mechanically induced long period gratings in liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Scolari, Lara; Lægsgaard, Jesper

    2007-01-01

    We demonstrate electrically and mechanically induced long period gratings (LPGs) in a photonic crystal fiber (PCF) filled with a highindex liquid crystal. The presence of the liquid crystal changes the guiding properties of the fiber from an index guiding fiber to a photonic bandgap guiding fiber...

  3. Electrically tunable Yb-doped fiber laser based on a liquid crystal photonic bandgap fiber device

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei

    2010-01-01

    We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a tunable liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate...

  4. Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

    Directory of Open Access Journals (Sweden)

    Yuriy Garbovskiy

    2015-11-01

    Full Text Available The presence of ions in liquid crystals is one of the grand challenges that hinder the application of liquid crystals in various devices, which include advanced 3-D and flexible displays, tunable lenses, etc. Not only do they compromise the overall performance of liquid crystal devices, ions are also responsible for slow response, image sticking, and image flickering, as well as many other negative effects. Even highly purified liquid crystal materials can get contaminated during the manufacturing process. Moreover, liquid crystals can degrade over time and generate ions. All of these factors raise the bar for their quality control, and increase the manufacturing cost of liquid crystal products. A decade of dedicated research has paved the way to the solution of the issues mentioned above through merging liquid crystals and nanotechnology. Nano-objects (guests that are embedded in the liquid crystals (hosts can trap ions, which decreases the ion concentration and electrical conductivity, and improves the electro-optical response of the host. In this paper, we (i review recently published works reporting the effects of nanoscale dopants on the electrical properties of liquid crystals; and (ii identify the most promising inorganic and organic nanomaterials suitable to capture ions in liquid crystals.

  5. Q-tensor model for electrokinetics in nematic liquid crystals

    Science.gov (United States)

    Tovkach, O. M.; Conklin, Christopher; Calderer, M. Carme; Golovaty, Dmitry; Lavrentovich, Oleg D.; Viñals, Jorge; Walkington, Noel J.

    2017-05-01

    We use a variational principle to derive a mathematical model for a nematic electrolyte in which the liquid crystalline component is described in terms of a second-rank order parameter tensor. The model extends the previously developed director-based theory and accounts for the presence of disclinations and possible biaxiality. We verify the model by considering a simple but illustrative example of liquid crystal-enabled electro-osmotic flow around a stationary dielectric spherical particle placed at the center of a large cylindrical container filled with a nematic electrolyte. Assuming homeotropic anchoring of the nematic on the surface of the particle and uniform distribution of the director on the surface of the container, we consider two configurations with a disclination equatorial ring and with a hyperbolic hedgehog, respectively. The computed electro-osmotic flows show a strong dependence on the director configurations and on the anisotropies of dielectric permittivity and electric conductivity of the nematic, characteristic of liquid crystal-enabled electrokinetics. Further, the simulations demonstrate space charge separation around the dielectric sphere, even in the case of isotropic permittivity and conductivity. This is in agreement with the induced-charge electroosmotic effect that occurs in an isotropic electrolyte when an applied field acts on the ionic charge it induces near a polarizable surface.

  6. 3D quantum liquid crystals by condensation of dislocation worldsheets

    Science.gov (United States)

    Beekman, Aron; Wu, Kai; Nissinen, Jaakko; Zaanen, Jan

    A solid can partially melt into a liquid crystal where rotational rigidity is maintained while translational symmetry is restored. The topological melting is caused by an unbinding of dislocations. We recently provided a comprehensive review of quantum dislocation-mediated melting in 2D (arXiv:1603.04254). Through a duality mapping, phonons turn into dual gauge fields mediating interactions between dislocations. Upon condensation of dislocations, the dual gauge fields undergo the Anderson-Higgs mechanism and become gapped, signaling the loss of shear rigidity. Here we extend this theory to three dimensions. Dislocations are now linelike objects, strings, tracing out worldsheets in spacetime, while the dual gauge-fields become two-form (Kalb-Ramond) fields. We obtain the Higgs phase of these two-form gauge fields. Translational symmetry can be restored in three, two or one directions leading to nematic, smectic or columnar quantum liquid crystals. We derive the spectrum of low-energy excitations and its linear response. Goldstone modes due to broken rotational symmetry as well as superconductivity emerge whenever translational symmetry is restored. The peculiar features of liquid-crystalline order can be probed by finite-momentum spectroscopy.

  7. An unexpected phosphate binding site in Glyceraldehyde 3-Phosphate Dehydrogenase: Crystal structures of apo, holo and ternary complex of Cryptosporidium parvum enzyme

    Directory of Open Access Journals (Sweden)

    Chattopadhyay Debasish

    2009-02-01

    Full Text Available Abstract Background The structure, function and reaction mechanism of glyceraldehyde 3-phosphate dehydrogenase (GAPDH have been extensively studied. Based on these studies, three anion binding sites have been identified, one 'Ps' site (for binding the C-3 phosphate of the substrate and two sites, 'Pi' and 'new Pi', for inorganic phosphate. According to the original flip-flop model, the substrate phosphate group switches from the 'Pi' to the 'Ps' site during the multistep reaction. In light of the discovery of the 'new Pi' site, a modified flip-flop mechanism, in which the C-3 phosphate of the substrate binds to the 'new Pi' site and flips to the 'Ps' site before the hydride transfer, was proposed. An alternative model based on a number of structures of B. stearothermophilus GAPDH ternary complexes (non-covalent and thioacyl intermediate proposes that in the ternary Michaelis complex the C-3 phosphate binds to the 'Ps' site and flips from the 'Ps' to the 'new Pi' site during or after the redox step. Results We determined the crystal structure of Cryptosporidium parvum GAPDH in the apo and holo (enzyme + NAD state and the structure of the ternary enzyme-cofactor-substrate complex using an active site mutant enzyme. The C. parvum GAPDH complex was prepared by pre-incubating the enzyme with substrate and cofactor, thereby allowing free movement of the protein structure and substrate molecules during their initial encounter. Sulfate and phosphate ions were excluded from purification and crystallization steps. The quality of the electron density map at 2Å resolution allowed unambiguous positioning of the substrate. In three subunits of the homotetramer the C-3 phosphate group of the non-covalently bound substrate is in the 'new Pi' site. A concomitant movement of the phosphate binding loop is observed in these three subunits. In the fourth subunit the C-3 phosphate occupies an unexpected site not seen before and the phosphate binding loop remains in

  8. The Sr-poor part of the Sr–{Pd,Pt}–{Si,Ge} systems: Phase equilibria and crystal structure of ternary phases

    Energy Technology Data Exchange (ETDEWEB)

    Romaka, V.V.; Falmbigl, M.; Grytsiv, A.; Rogl, P., E-mail: peter.franz.rogl@univie.ac.at

    2015-01-05

    Highlights: • Phase diagrams of the Sr-poor part of Sr–{Pd,Pt}–Si (900 °C) and Sr–{Pd,Pt}–Ge (700 °C) systems were constructed. • The crystal structure for three novel compounds SrPd{sub 0.3}Si{sub 1.7}, SrPt{sub 0.3}Si{sub 1.7} and SrPd{sub 5.9}Si{sub 6.1} was refined. • DFT calculations predicted metallic behavior for SrPdSi{sub 3}, SrPtSi{sub 3}, SrPd{sub 0.3}Si{sub 1.7} and SrPd{sub 6}Si{sub 6}. - Abstract: Phase relations have been established by electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD) for the Sr-poor part of four ternary systems: Sr–{Pd,Pt}–Si at 900 °C and Sr–{Pd,Pt}–Ge at 700 °C. In the Sr–Pd–Si system the formation of the silicide SrPdSi{sub 3} (BaNiSn{sub 3}-type) was confirmed and a small homogeneity region was found. Furthermore, two novel compounds were detected and their crystal structure was refined from X-ray powder patterns: SrPd{sub 0.3}Si{sub 1.7} (AlB{sub 2}-type) and SrPd{sub 5.9}Si{sub 6.1} (own-type). In the Sr–Pt–Si ternary system a novel compound with AlB{sub 2}-type was discovered (SrPt{sub 0.3}Si{sub 1.7}), whereas SrPtSi{sub 3} with the BaNiSn{sub 3}-type was confirmed. Two more compounds were detected by EPMA, but their crystal structure remains unknown. In the Sr–{Pd,Pt}–Ge systems no new compounds were observed, but the existence of SrPdGe{sub 3} and SrPtGe{sub 3} (both adopt the BaNiSn{sub 3} structure type), and SrPt{sub 4}Ge{sub 12}, crystallizing in the LaFe{sub 4}Sb{sub 12} structure type, was corroborated. For selected ternary silicides the electronic structure was evaluated by DFT calculations.

  9. Dielectric relaxation studies in 5CB nematic liquid crystal at 9 GHz ...

    Indian Academy of Sciences (India)

    5CB nematic liquid crystal are measured using microwave cavity technique under the influence of an external magnetic field at 9 GHz ... Dielectric relaxation; phase transition; liquid crystals; microwaves. PACS Nos 64.70.-p; 65.40. ... liquids, are preferentially aligned along a common axis, called director. The dielectric prop-.

  10. Asymmetric flavone-based liquid crystals: synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Timmons, Daren J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Jordan, Abraham J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Kirchon, Angelo A. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Murthy, N. Sanjeeva [New Jersey Center for Biomaterials, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Siemers, Troy J. [Department of Applied Mathematics, Virginia Military Institute, Lexington, VA, USA; Harrison, Daniel P. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Slebodnick, Carla [Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA

    2017-02-01

    A series of flavones (n-F) substituted at the 4', and 6 positions was prepared, characterised by NMR (1H,13C), HRMS, and studied for liquid crystal properties. The 4'-alkoxy,6-methoxyflavones (4-F–16-F) exhibit varying ranges of nematic and smectic A phases as evidenced by polarised optical microscopy and differential scanning calorimetry (DSC). As the tail length is increased, the smectic phase becomes more prevalent. Smectic phases for (8-F–16-F) were further analysed by powder X-ray diffraction (XRD), and the rate of structural transformations was explored by combined DSC/XRD studies. Flavonol 6-F–OH was also prepared but no mesogenic behaviour was observed. The molecular structures of 6-F and 6-F–OH were determined by single-crystal XRD and help to explain the differences in material properties. Additionally, fluorescence and electrochemical studies were conducted on solutions of n-F.

  11. Local structural ordering in surface-confined liquid crystals

    Science.gov (United States)

    Śliwa, I.; Jeżewski, W.; Zakharov, A. V.

    2017-06-01

    The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. Extending the McMillan mean field theory to include finite systems, it has been shown that confining surfaces can induce complex orientational and translational ordering of molecules. Typically, local smectic A, nematic, and isotropic phases have been shown to coexist in certain temperature ranges, provided that confining cells are sufficiently thick, albeit finite. Due to the nonlocality of surface interactions, the spatial arrangement of these local phases can display, in general, an unexpected complexity along the surface normal direction. In particular, molecules located in the vicinity of surfaces can still be organized in smectic layers, even though nematic and/or isotropic order can simultaneously appear in the interior of cells. The resulting surface freezing of smectic layers has been confirmed to occur even for rather weak surface interactions. The surface interactions cannot, however, prevent smectic layers from melting relatively close to system boundaries, even when molecules are still arranged in layers within the central region of the system. The internal interfaces, separating individual liquid-crystal phases, are demonstrated here to form fronts of local finite-size transitions that move across cells under temperature changes. Although the complex molecular ordering in surface confined liquid-crystal systems can essentially be controlled by temperature variations, specific thermal properties of these systems, especially the nature of the local transitions, are argued to be strongly conditioned to the degree of molecular packing.

  12. Asymmetric electrooptic response in a nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dascalu, Constanta [Politechnica University of Bucharest, Bucharest (Romania)

    2001-06-01

    An asymmetric electrooptic response in nematic liquid crystal (LC) has been obtained. The liquid crystal hybrid cell was made by using a standard configuration. One of the ITO (Indium Tin Oxide) electrodes was covered with a surfactant, which induces a homeotropic alignment. The second of the indium tin oxide electrodes was covered by a thin layer of photopolymer, which was previously mixed with an acid, which favours a process of release of protons. Such cations are responsible of electrochemical process in the LC leading to an asymmetric electrooptic response, which depend on the polarity of the applied electric field. This fact is due to an internal field, which change the effective voltage thresholds for the reorientation of the liquid crystal. During the anodic polarization, the optical switching is inhibited because the effective field decreases below the threshold value. On contrary for the opposite polarization the effective field is enough to determine a homeotropic alignment. [Spanish] Se ha obtenido una respuesta electro-optica asimetrica en cristales liquidos neumaticos. La celula hibrida de cristal liquido fue construida utilizando una configuracion estandar. Uno de los electrodos ITO fue cubierto con una pelicula delgada de material organico para inducir una alineacion homeotropa. El otro electrodo ITO fue cubierto con una pelicula delgada de fotopolimero anteriormente mezclada con un acido para favorecer la emision de protones. Estos cationes son responsables del proceso electroquimico en LC, conduciendo a una respuesta electro-optica asimetrica que depende de la polaridad del campo electrico aplicado. Este efecto es originado por un campo interno que cambia el umbral efectivo del voltaje para la reorientacion del cristal liquido. Durante la polarizacion anodica, la conmutacion optica se inhibe debido a que el campo efectivo disminuye abajo del valor del umbral. Por el contrario, para la polarizacion opuesta el campo efectivo es suficiente para

  13. Large magnetic entropy change of Gd-based ternary bulk metallic glass in liquid-nitrogen temperature range

    Science.gov (United States)

    Fu, H.; Zhang, X. Y.; Yu, H. J.; Teng, B. H.; Zu, X. T.

    2008-01-01

    Gd 60Co 26Al 14 bulk metallic glass (BMG) with a diameter of 3 mm was prepared by arc-melting and copper-mold suck-casting. X-ray diffraction (XRD) results show that the as-cast Gd 60Co 26Al 14 rod consists of a wholly amorphous phase. Differential scanning calorimetry (DSC) measurements indicated that one glass transition temperature (Tg) and two crystallization temperatures (TX) occur at 570, 602, and 642 K, respectively. Moreover, two Curie temperatures of 82 and 128 K, which correspond to the two amorphous phases in the DSC trace, were determined from the thermo-magnetization curve. The maximal magnetic entropy change (ΔSM) under 0-5 T is about 10.1 J/kg K at 75 K and the refrigerant capacity (RC) is about 556 J/kg, which makes Gd 60Co 26Al 14 BMG a promising candidate for magnetic refrigerant near liquid-nitrogen temperatures.

  14. Colloid-in-Liquid Crystal Gels Formed via Spinodal Decomposition

    Science.gov (United States)

    Pal, Santanu Kumar; de Pablo, Juan J.

    2014-01-01

    We report that colloid-in-liquid crystal (CLC) gels can be formed via a two-step process that involves spinodal decomposition of a dispersion of colloidal particles in an isotropic phase of mesogens followed by nucleation of nematic domains within the colloidal network defined by the spinodal process. This pathway contrasts to previously reported routes leading to the formation of CLC gels, which have involved entanglement of defects or exclusion of particles from growing nematic domains. The new route provides the basis of simple design rules that enable control of the microstructure and dynamic mechanical properties of the gels. PMID:24651134

  15. Single Molecule Studies on Dynamics in Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Daniela Täuber

    2013-09-01

    Full Text Available Single molecule (SM methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC. Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.

  16. Vector beams generated by tunable liquid crystal polarization holograms

    Science.gov (United States)

    Ruiz, U.; Pagliusi, P.; Provenzano, C.; Cipparrone, G.

    2017-04-01

    Two optically coupled nematic liquid crystal (NLC) polarization holograms (PHs) enable nearly 100% generation efficiency for vector beams (VBs) with spatially variant phase and polarization. Adopting a spatial light modulator assisted holographic approach, the PHs are recorded in the photoaligning substrates of the NLC cell and amplified by the NLC bulk. Owing to negligible NLC absorption at the visible and near infrared wavelengths and the ability to electrically adjust its optical birefringence, a single device allows us to generate VBs with the highest possible efficiency at any wavelength in the transparency range. In particular, we report the generation of VBs with an efficiency of 96% at a wavelength of 633 nm.

  17. Cholesteric liquid crystals as multi-purpose sensor materials

    Energy Technology Data Exchange (ETDEWEB)

    Lisetski, L. N. [National Academy of Sciences of Ukraine, Kharkov (Ukraine)

    2005-03-15

    New possibilities are discussed for Cholesteric Liquid Crystals (CLC) as sensor materials for detection of ionizing radiation, biologically active UV radiation, and the presence of hazardous vapors in atmosphere. A distinguishing property of CLC-based detectors is their 'bioequivalence', i.e., mechanisms of their response to external factors essentially imitate the corresponding mechanisms of biological tissues. Such detectors can ensure sufficiently high sensitivity to make feasible their use as alarm indicators or in biophysical studies. Specific examples are given of sensor compositions and their response characteristics.

  18. Graphene electrodes for adaptive liquid crystal contact lenses.

    Science.gov (United States)

    Kaur, S; Kim, Y-J; Milton, H; Mistry, D; Syed, I M; Bailey, J; Novoselov, K S; Jones, J C; Morgan, P B; Clamp, J; Gleeson, H F

    2016-04-18

    The superlatives of graphene cover a whole range of properties: electrical, chemical, mechanical, thermal and others. These special properties earn graphene a place in current or future applications. Here we demonstrate one such application - adaptive contact lenses based on liquid crystals, where simultaneously the high electrical conductivity, transparency, flexibility and elasticity of graphene are being utilised. In our devices graphene is used as a transparent conductive coating on curved PMMA substrates. The adaptive lenses provide a + 0.7 D change in optical power with an applied voltage of 7.1 Vrms - perfect to correct presbyopia, the age-related condition that limits the near focus ability of the eye.

  19. Liquid Crystal Photonic bandgap Fibers: Modeling and Devices

    DEFF Research Database (Denmark)

    Weirich, Johannes

    In this PhD thesis an experimental and numerical investigation of liquid crystal infiltrated photonic bandgap fibers (LCPBGs) is presented. A simulation scheme for modeling LCPBG devices including electrical tunability is presented. New experimental techniques, boundary coating and the applications...... of monomer added LCs, are investigated. Waveplates based on LCPBGs and a tunable polarization maintaining filter are developed. An on-chip tunable notch filter based on long period gratings is presented. Furthermore, the application of a LCPBG device for the electrical control of a fiber laser...

  20. Laser Coherence Meter Based on Nanostructured Liquid Crystals

    Directory of Open Access Journals (Sweden)

    A. Anczykowska

    2013-01-01

    Full Text Available We present the method for coherence length measurement using coherence meter based on hybrid liquid crystal structures doped with gold nanoparticles. The results indicate that the method is able to determine the coherence length of coherent light sources with precision of 0.01 m at wavelength range from 200 to 800 nm for wide range of initial beam powers starting from 1 mW. Given the increasing use of laser technology in industry, military, or medicine, our research may open up a possible route for the development of improved techniques of coherent diagnostic light sources.

  1. Self-Assembled Supramolecular Architectures Lyotropic Liquid Crystals

    CERN Document Server

    Garti, Nissim

    2012-01-01

    This book will describe fundamentals and recent developments in the area of Self-Assembled Supramolecular Architecture and their relevance to the  understanding of the functionality of  membranes  as delivery systems for active ingredients. As the heirarchial architectures determine their performance capabilities, attention will be paid to theoretical and design aspects related to the construction of lyotropic liquid crystals: mesophases such as lamellar, hexagonal, cubic, sponge phase micellosomes. The book will bring to the reader mechanistic aspects, compositional c

  2. Mathematical analysis of composite systems of liquid crystal and polymer

    Science.gov (United States)

    Shen, Quan

    This thesis deals with mathematical modeling of the composite material consisting of liquid crystal and polymer. Such systems are important in the applications. The mathematical work consists in minimizing the total free energy of a system in a geometrically complex domain. The total energy consists of the bulk Oseen-Frank free energy of the liquid crystal plus the surface contribution. The latter arises as a result of the contact interaction between the liquid crystal and the polymeric component. The first part of the work presents a two-dimensional prototype model. The effective equations for the composite configurations are obtained by means of homogenization limits, and subsequently analyzed and computed by numerical methods. One of the main mathematical difficulties of such analyses is the presence of defects in the model. This becomes an important issue in the study of physically realistic three-dimensional configurations. In order to overcome such a difficulty, the original model is replaced by a relaxed one: while the unit vector constraint is omitted, a penalty term is included in the energy. The idea is borrowed from the Ginzburg-Landau modeling of superconductivity and the unit director condition will be satisfied approximately while allowing for defects (i.e., points or lines where the length of director is zero). The effective equations are studied, and the relaxation of the length of the directors is eventually removed through the limit of the penalty term. The external magnetic field is added and the effect on the composite system is discussed. The last part of the thesis deals with systems of liquid crystal droplets in a polymeric isotropic matrix. The droplet configurations are of bipolar type, i.e., spherical-type shapes with two defects as opposite poles. The dipole line provides a new tool to construct anisotropic systems. A mathematical model for bipolar droplet is constructed and analyzed for both fixed and free boundary problems. The thesis

  3. Final Report: Biaxiality in Nematic and Smectic Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satyendra; Quan, Li; Srinivasarao, Mohan; Agra-Kooijman, Dena; Rey, Alejandro

    2017-01-24

    During the award period, the project team explored several phenomena in a diverse group of soft condensed matter systems. These include understanding of the structure of the newly discovered twist-bend nematic phase, solving the mystery of de Vries smectic phases, probing of interesting associations and defect structures in chromonic liquid crystalline systems, dispersions of ferroelectric nanoparticles in smectic liquid crystals, investigations of newly synthesized light sensitive and energy harvesting materials with highly desirable transport properties. Our findings are summarized in the following report followed by a list of 36 publications and 37 conference presentations. We achieved this with the support of Basic Sciences Division of the US DOE for which we are thankful.

  4. Chiral power change upon photoisomerization in twisted nematic liquid crystals.

    Science.gov (United States)

    Simoncelli, Sabrina; Aramendía, Pedro F

    2015-05-05

    In this work, we use the photoisomerization of azobenzenes, a phenanthrospirooxazine, and a fulgide in a twisted nematic liquid crystalline phase to change the chiral twisting power of the system. The changes are probed by the rotatory power of linearly polarized light. Time resolved and steady state experiments are carried out. The chiral change and the photoisomerization process have similar characteristic recovery times and activation energy, thus probing that the change is induced by the modification in the chemical composition of the photochromic dopant system. The amplitude of the light twisting power change correlates with the order change in the liquid crystal (LC) but not with the modification in the absorption characteristics of the system. This indicates that the driving force of the chiral change is the microscopic order modification in the LC phase that affects the helical pitch of the phase. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Confined Photovoltaic Fields in a Photo-Responsive Liquid Crystal Test Cell (Preprint)

    Science.gov (United States)

    2017-08-11

    AFRL-RX-WP-JA-2017-0428 CONFINED PHOTOVOLTAIC FIELDS IN A PHOTO- RESPONSIVE LIQUID CRYSTAL TEST CELL (PREPRINT) Atefeh...TITLE AND SUBTITLE CONFINED PHOTOVOLTAIC FIELDS IN A PHOTO- RESPONSIVE LIQUID CRYSTAL TEST CELL (PREPRINT) 5a. CONTRACT NUMBER FA8650-16-D...hybridized photo responsive liquid crystal test cells are reported, where iron doped lithium niobate substrates were used to photo generate electric

  6. Photoluminescence analysis of self induced planer alignment in azo dye dispersed nematic liquid crystal complex

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rishi, E-mail: kkraina@gmail.com; Sood, Srishti, E-mail: kkraina@gmail.com; Raina, K. K., E-mail: kkraina@gmail.com [School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

    2014-04-24

    We have developed azo dye doped nematic liquid crystal complex for advanced photonic liquid crystal display technology aspects. Disperse orange azo dye self introduced planer alignment in the nematic liquid crystal without any surface anchoring treatment. Planer alignment was characterized by optical polarizing microscopy. The electro-optical switching response of dye disperse planer aligned nematic cell was investigated as a function of applied voltage with the help of photoluminescence spectrophotometer for the tuning of photoluminescence contrast.

  7. Security devices based on liquid crystals doped with a colour dye

    OpenAIRE

    Carrasco Vela, Carlos; Quintana Arregui, Patxi Xabier; Otón, E.; Geday, Morten Andreas; Otón Sánchez, José Manuel

    2011-01-01

    Liquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices. Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multiple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC ce...

  8. Binary and ternary (liquid + liquid) equilibrium for {l_brace}methylcyclohexane (1) + toluene (2) + 1-hexyl-3-methylimidazolium tetracyanoborate (3)/1-butyl-3-methylimidazolium tetracyanoborate (3){r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, Juan Pablo, E-mail: j.p.gutierrez-hernandez@tue.nl [Eindhoven University of Technology, Den Dolech 2, Eindhoven 5600 (Netherlands); Meindersma, Wytze; Haan, Andre B. de [Eindhoven University of Technology, Den Dolech 2, Eindhoven 5600 (Netherlands)

    2011-11-15

    Highlights: > Binary and ternary extractions for two ionic liquids with organic compounds were measured. > NRTL and UNIQUAC thermodynamic models were used to fit the experimental data. > UNIQUAC model gives better predictions than the NRTL model. > Ionic liquids showed interesting properties as solvents to be applied in separation processes. - Abstract: This paper focuses on the study of the solubility behaviour of 1-hexyl-3-methylimidazolium tetracyanoborate [HMIM][TCB] and 1-butyl-3-methylimidazolium tetracyanoborate [BMIM][TCB] in combination with methylcyclohexane and toluene as representatives for non-aromatic and aromatic components. Binary and ternary (liquid + liquid) equilibrium data were collected at three different temperatures and at atmospheric pressure (0.1 MPa). The experimental data were well-correlated with the NRTL and UNIQUAC thermodynamic models; however, the UNIQUAC model gave better predictions than the NRTL, with a root mean square error below 0.97%. The non-aromatic/aromatic selectivities of the ionic liquids make them suitable solvents to be used in extractive distillation processes.

  9. Electrically controlled optical bandgap in a twisted photonic liquid crystal

    Science.gov (United States)

    Molina, Ismael; Adrián Reyes, J.; Avendaño, Carlos G.

    2011-06-01

    We consider a one-dimensional twisted photonic liquid crystal, which consists of N nematic liquid crystal slabs in a twisted configuration alternated by N isotropic dielectric layers under the action of a dc electric field (Edc) aligned along the periodicity axis. We write and solve numerically the corresponding Euler-Lagrange equations describing the nematic layer configuration. We express Maxwell's equations in a 4×4 matrix representation, and by using the transfer matrix formalism, we obtain the optical band structures at arbitrary incidence angles and different external electric fields. We have found that there exists a strong dependence of electric field on the transmission and reflection spectra in enhancing and extinguishing bandgaps. The analysis presented here allow us to propose an electrically shiftable universal rejection filter for incident waves of left- and right-circular polarization. It is observed that by increasing the electric field we can highly enhance the cross-polarized reflection bandgaps and suppress the co-polarized ones. We analyzed the optical spectra for different values of twist angle, different ratios between dielectric and nematic layer thicknesses and number of layers N. Also, we showed that the cross-polarized bandgaps are blue-shifted as the incidence angle gets larger.

  10. Stabilizing blue phase liquid crystals with linearly polarized UV light

    Science.gov (United States)

    Xu, Daming; Yuan, Jiamin; Schadt, Martin; Yan, Jing; Wu, Shin-Tson

    2015-03-01

    Polymer-stabilized blue-phase liquid crystal (PS-BPLC) has become an increasingly important technology trend for information display and photonic applications. BPLC exhibits several attractive features, such as reasonably wide temperature range, submillisecond gray-to-gray response time, no need for alignment layer, optically isotropic voltageoff state, and large cell gap tolerance when an in-plane switching (IPS) cell is employed. However, some bottlenecks such as high operation voltage, relatively low transmittance, and noticeable hysteresis and prolonged response time at high field region for IPS mode, still remain to be overcome before widespread application of BPLC can be realized. To reduce operation voltage, both new BPLC materials and new device structures have been investigated. In this paper, we demonstrate the stabilization a photopolymer-embedded blue phase liquid crystal precursor using a linearly polarized UV light for first time. When the UV polarization axis is perpendicular to the stripe electrodes of an IPS cell, anisotropic polymer networks are formed through the linear photo-polymerization process and the electrostriction effect is suppressed. As a result, the measured hysteresis is dramatically reduced from 6.95% to 0.36% and the response time shortened by ~2X compared to unpolarized UV exposure. To induce larger anisotropy in polymer networks for mitigating the electrostriction effect, high-intensity linearly polarized UV exposure is preferred. It is foreseeable this method will guide future BPLC device and material development as well as manufacturing process. The dawn of BPLCD is near.

  11. Controlled Growth of Organic Semiconductor Films Using Liquid Crystal Solvents

    Science.gov (United States)

    Bufkin, Kevin; Ohlson, Brooks; Hillman, Ben; Johnson, Brad; Patrick, David

    2008-05-01

    Interest in using organic semiconductors in applications such as large area displays, photovoltaic devices, and RFID tags stems in part from their prospects for enabling significantly reduced manufacturing costs compared to traditional inorganic semiconductors. However many of the best performing prototype devices produced so far have involved expensive or time-consuming fabrication methods, such as the use of single crystals or thin films deposited under high vacuum conditions. We present a new approach for growing low molecular weight organic crystalline films at ambient conditions based on a vapor-liquid-solid growth mechanism using thermotropic nematic liquid crystal (LC) solvents. Tetracene is deposited via atmospheric-pressure sublimation onto substrates coated by a LC layer oriented using rubbed polyimide, producing films that are highly crystalline, with large grain sizes, and possessing macroscopic uniaxial orientation. This poster will describe the growth mechanism, discuss the effects of processing conditions such as LC layer thickness, substrate temperature and flux rate, and compare the results to a model of deposition-diffusion aggregation accounting for the finite thickness of the solvent layer.

  12. Surface dynamics and mechanics in liquid crystal polymer coatings

    Science.gov (United States)

    Liu, Danqing; Broer, Dirk J.

    2015-03-01

    Based on liquid crystal networks we developed `smart' coatings with responsive surface topographies. Either by prepatterning or by the formation of self-organized structures they can be switched on and off in a pre-designed manner. Here we provide an overview of our methods to generate coatings that form surface structures upon the actuation by light. The coating oscillates between a flat surface and a surface with pre-designed 3D micro-patterns by modulating a light source. With recent developments in solid state lighting, light is an attractive trigger medium as it can be integrated in a device for local control or can be used remotely for flood or localized exposure. The basic principle of formation of surface topographies is based on the change of molecular organization in ordered liquid crystal polymer networks. The change in order leads to anisotropic dimensional changes with contraction along the director and expansion to the two perpendicular directions and an increase in volume by the formation of free volume. These two effects work in concert to provide local expansion and contraction in the coating steered by the local direction of molecular orientation. The surface deformation, expressed as the height difference between the activated regions and the non-activated regions divided by the initial film thickness, is of the order of 20%. Switching occurs immediately when the light is switched `on' and `off' and takes several tens of seconds.

  13. Correlation measurements of light transmittance in polymer dispersed liquid crystals

    Science.gov (United States)

    Maksimyak, P. P.; Nehrych, A. L.

    2015-11-01

    The methods of correlation optics are for the first time applied to study structure of liquid crystal (LC) - polymer (P) composites at various concentrations of LC and P. Their phase correlation function (PCF) was obtained considering LC-P composite as a random phase screen. The amplitude of PCF contains information about number of LC domains and structure of LC director inside of them, while a half-width of this function is connected with a size of these domains. We studied unpowered and powered composite layers with a thickness of 5 μm. As liquid crystal and polymer were used nematic LC E7 from Merck and photopolymer composition NOA65 from Norland. Concentration of polymer φP was varied in a range 10-55 vol. %. In good agreement with previous studies by SEM technique we detected monotone decrease of LC domains with concentration of polymer. With application of electric field, amplitude of PCF behaves differently for the samples with different polymer content. For the samples with φP>35 vol. % (samples having morphology of polymer dispersed LC), this dependence is monotonic. In turn, if φPpolymer network LC morphology), the amplitude of PCF non-monotonically depends on the applied voltage going through a maximum. The latter fact is explained by transformation of orientational defects of LC phase with the applied voltage.

  14. Ultra-high-resolution time projection chambers with liquid crystal backplanes

    Energy Technology Data Exchange (ETDEWEB)

    Monreal, Benjamin

    2014-10-15

    We investigated the possibility of incorporating a liquid-crystal device into a gas ionization detector. After extensive R&D on several candidate liquid-crystal technologies, we developed some novel materials allowing twisted nematic liquid-crystal layers to be coupled directly to gas ionization counters. However, the resulting structures were unsuitable for large-scale or practical use. We tested several technologies known to result in mechanically-robust liquid crystal electrooptic layers, but found poor behavior in the detector context.

  15. Optical Study of Liquid Crystal Lens Doped with Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Hui LI

    2016-05-01

    Full Text Available In this paper, a new kind of electrically controlled liquid crystal lens, which respond in a relatively fast time, is presented. The multiwalled carbon nanotubes are doped into liquid crystal to fabricate the liquid crystal lens. As 0.02 % concentration of multiwalled carbon nanotubes is uniformly distributed in the liquid crystal, the optical features of the liquid crystal lens are obviously improved. The liquid crystal lens with a diameter of 2.0 mm was fabricated with about 0.2 s response time and less than 5 Vrms applied voltage. The focal length can vary from 16 to 510 mm, and the operation voltage changes from 1.0 to 5.5 Vrms. This liquid crystal lens has the very attractive feature of submillisecond response time, which is a much faster response time in comparison with conventional liquid crystal lens. Thus, this kind of liquid crystal lens has high potential for implementation in many practical imaging applications and imaging commercialisation.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12911

  16. Siloxane head groups and spacers in calamitic liquid crystals

    Science.gov (United States)

    Kloess, Petra Sabine

    Organo-siloxanes are a compromise between a low molar mass liquid crystal and a liquid crystalline side chain polysiloxane polymer. Like polymers the compounds segregate in mesogen rich layers and siloxane rich layers, but like low molar mass compounds the viscosity is in the magnitude of classic LMM liquid crystals. The siloxane group can be used as a head group, a linear linking group and a cyclic linking group. Up to four mesogens can be connected. In the present work small siloxane groups were grafted onto a variety of mesogens in a variety of sizes and shapes. As a steroidal mesogen cholestanol derivatives, as aromatic cores laterally substituted biphenyl benzoates were synthesised and characterised. All liquid crystals investigated were synthesised via established procedures. Olefinic terminated precursor compounds were hydrosilylated with smaller siloxane groups. Structure and phase properties were determined via optical microscopy, differential scanning microscopy, X-ray diffraction and dilatometry. The helielectric compounds were also characterised electro-optically, i.e. tilt angle, spontaneous polarisation and optical response time. To investigate the role of the siloxane in steroidal liquid crystals three different series of cholestanol derivatives were synthesised and characterised. The mesophase behaviour depended strongly on the spacer length, the number of mesogens attached to the siloxane group and the siloxane length. Mono- and bimesogenic compounds exhibited an odd-even effect on the melting transition, whereas the clearing temperatures increased with an increase in spacer length. All LMM organo- siloxanes are liquid crystalline at ambient temperature. The analogous side chain polysiloxanes exhibited significantly higher transition temperatures and viscosity. A series of androstane derivatives revealed the importance of a short branched alkyl tail for the occurance of a broad mesophase. Biphenyl benzoates are known to exhibit ferroelectric

  17. Crystal structure of the TbZnSn{sub 2} and TbZnSn ternary compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pavlyuk, V. [Ivan Franko National University of Lviv, Department of Inorganic Chemistry, Kyryla and Mefodia Street 6, 79005 Lviv (Ukraine); Czestochowa Jan Dlugosz University, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200 Czestochowa (Poland)], E-mail: pavlyuk@franko.lviv.ua; Oshchapovsky, I. [Ivan Franko National University of Lviv, Department of Inorganic Chemistry, Kyryla and Mefodia Street 6, 79005 Lviv (Ukraine); Marciniak, B. [Czestochowa Jan Dlugosz University, Institute of Chemistry and Environmental Protection, al. Armii Krajowej 13/15, 42200 Czestochowa (Poland)

    2009-05-27

    The crystal structures of the TbZnSn{sub 2} and TbZnSn compounds were determined by X-ray single crystal diffraction. The TbZnSn{sub 2} compound crystallizes with the HfCuSi{sub 2} structure type (space group P4/nmm) and TbZnSn crystallizes with the YPtAs structure type (space group P6{sub 3}/mmc)

  18. Tunable Mach-Zehnder interferometer in a two-dimensional photonic crystal with liquid crystal infiltration

    Science.gov (United States)

    Chen, Xiyao; Dong, Xinyong; Hu, Juan Juan; Shum, Ping; Wang, Yufei; Qiu, Yishen; Lin, Guimin; Hong, Hailian

    2007-09-01

    A theoretical model of a tunable Mach-Zehnder interferometer (TMZI) constructed in a 2D photonic crystal is proposed. The 2D PhC consists of a square lattice of cylindric air holes in silicon. The TMZI includes two mirrors and two splitters. Lights propagate between them employing self-collimation effect. The two interferometer branches have different path lengths. Parts of the longer branch are infiltrated with a kind of liquid crystal (LC) whose ordinary and extraordinary refractive indices are 1.522 and 1.706, respectively. The transmission spectra at two MZI output ports are in the shape of sinusoidal curves and have a uniform peak spacing 0.0017c/a in the frequency range from 0.26c/a to 0.27c/a. When the effective refractive index n eff of the liquid crystal is increased from 1.522 to 1.706, the peaks shift to the lower frequencies over 0.0017c/a while the peak spacing is almost kept unchanged. So this TMZI can work as a tunble power splitter or an optical switch. For the central operating wavelength around 1550nm, its dimensions are only about tens of microns. So this device may be applied to photonic integrated circuits.

  19. Incidence of crystal growth conditions on the formation of macroscopic liquid inclusions in ciclopirox crystals

    Science.gov (United States)

    Waldschmidt, Audrey; Dupray, Valérie; Berton, Benjamin; Couvrat, Nicolas; Petit, Samuel; Coquerel, Gérard

    2012-03-01

    Using an accurate and rigorous protocol, the crystal growth behavior in solution of the antifungal drug ciclopirox was investigated with the aim to identify the experimental factors responsible for the appearance of macroscopic inclusions of saturated solution. Counterintuitively, these inclusions are produced only when the relative supersaturation is below a critical threshold; simultaneously the crystals exhibit a hexagonal morphology. An increase in the driving force leads to a rod-shaped morphology without inclusion and without any change of the crystal phase, as confirmed by X-ray diffraction. The correlation between this morphological transition and the occurrence of liquid inclusions could be rationalized by considering the associated change of growth rates of {(1 1 1)} and {(1 1 -1)} faces. However, the nature of the solvent, the presence of impurities and diffusion in solution appeared to have no detectable incidence on the formation of liquid inclusions, inducing that the presumed contribution of a chemical adsorption phenomenon—side products or solvents—could not be established.

  20. Pulsed zero field NMR of solids and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, A.M.

    1987-02-01

    This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs.

  1. Self-orientation effect of liquid crystals on holographic polymer-dispersed liquid crystal and distributed feedback lasers

    Science.gov (United States)

    Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Zhao, Haifeng; Cao, Zhaoliang; Xuan, Li

    2017-07-01

    The average orientation of a liquid crystal (LC) director to the grating formation, morphology, and switching properties of a holographic polymer-dispersed liquid crystal (HPDLC) grating was systematically investigated in this study. The grating possessed high diffraction efficiency and low scattering with the LC director being parallel to the grating vector. The scanning electron microscope confirmed the well-defined morphology with the LC director being parallel to the grating vector. The grating was easily switched when the LC director was perpendicular to the grating vector. Moreover, polarization excitation was performed to investigate the polarization dependence behavior of the HPDLC-distributed feedback (DFB) laser. The results confirmed that the HPDLC grating is suitable as a laser oscillation when the LC director is parallel to the grating vector. Finally, the tuning range was obtained for the HPDLC DFB laser by applying an external electric field. The tunability, ease of fabrication, and mass production make the HPDLC DFB lasers suitable as smart laser sources for spectroscopy and communication.

  2. Anti-mackay polyicosahedral clusters in La-Ni-Mg ternary compounds: synthesis and crystal structure of the La(43)Ni(17)Mg(5) new intermetallic phase.

    Science.gov (United States)

    Solokha, Pavlo; De Negri, Serena; Pavlyuk, Volodymyr; Saccone, Adriana

    2009-12-21

    The crystal structure of the complex La(43)Ni(17)Mg(5) ternary phase was solved and refined from X-ray single crystal diffraction data. It is characterized by a very large unit cell and represents a new structure type: La(43)Ni(17)Mg(5) - orthorhombic, Cmcm, oS260, a = 10.1895(3), b = 17.6044(14), c = 42.170(3) A, Z = 4, wR1 = 0.0598, wR2 = 0.0897, 4157 F(2) values, 176 variables. The crystal structures of the La-rich La-Ni-Mg intermetallic phases La(4)NiMg, La(23)Ni(7)Mg(4), and La(43)Ni(17)Mg(5) have been comparatively analyzed. The constitutive fragments of these structures are binary polyicosahedral core-shell clusters of Mg(4)La(22) and Mg(5)La(24) compositions together with binary polytetrahedral clusters of nickel and lanthanum atoms. The structures of the Mg-La clusters are described in detail as a unique feature of the analyzed intermetallic phases; the dodecahedral Voronoi polyhedra are proposed as a useful tool to characterize polyicosahedral clusters. The arrangements of the building units in the studied phases show some regularities; particularly the i(4)3, i(5)3 and L-i(4) units, made up of polyicosahedral clusters and analogous to the Kreiner i(3) and L units, are proposed as structural blocks.

  3. Crystal structures of a ddATP-, ddTTP-, ddCTP, and ddGTP- trapped ternary complex of Klentaq1: Insights into nucleotide incorporation and selectivity

    OpenAIRE

    Li,Ying; Waksman, Gabriel

    2001-01-01

    The mechanism by which DNA polymerase I enzymes function has been the subject of extensive biochemical and structural studies. We previously determined the structure of a ternary complex of the large fragment of DNA polymerase I from Thermus aquaticus (Klentaq1) bound to a primer/template DNA and a dideoxycytidine 5′-triphosphate (ddCTP). In this report, we present the details of the 2.3-Å resolution crystal structures of three additional ternary complexes of Klentaq1 bound to a primer/templa...

  4. Flat liquid crystal diffractive lenses with variable focus and magnification

    Science.gov (United States)

    Valley, Pouria

    Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera

  5. Ultrashort polarization rotator based on spiral photonic crystal fiber aided by liquid crystal.

    Science.gov (United States)

    Yu, Lin; Chen, Lei; Zhang, Weigang; Zhang, Yunshan; Wang, Song; Zhang, Yanxin; Yan, Tieyi; Yang, Jiang

    2017-09-01

    A novel polarization rotator (PR) is proposed based on a spiral photonic crystal fiber aided by liquid crystal. The proposed PR has an ultrashort length of only ∼4.17  μm and a low cross talk of ∼-20.93  dB, and the proposed PR offers a nearly 100% polarization conversion efficiency for the whole C-band. In addition, a large temperature tolerance of ∼±5°C and a large rotation angle tolerance of ∼±4° can be accepted based on the full-vector finite-element method simulation. The proposed PR is a potentially effective polarization conversion device for applications in modern communication systems.

  6. The Effect of Thermal Cycling on Crystal-Liquid Separation During Lunar Magma Ocean Differentiation

    Science.gov (United States)

    Mills, Ryan D.

    2013-01-01

    Differentiation of magma oceans likely involves a mixture of fractional and equilibrium crystallization [1]. The existence of: 1) large volumes of anorthosite in the lunar highlands and 2) the incompatible- rich (KREEP) reservoir suggests that fractional crystallization may have dominated during differentiation of the Moon. For this to have occurred, crystal fractionation must have been remarkably efficient. Several authors [e.g. 2, 3] have hypothesized that equilibrium crystallization would have dominated early in differentiation of magma oceans because of crystal entrainment during turbulent convection. However, recent numerical modeling [4] suggests that crystal settling could have occurred throughout the entire solidification history of the lunar magma ocean if crystals were large and crystal fraction was low. These results indicate that the crystal size distribution could have played an important role in differentiation of the lunar magma ocean. Here, I suggest that thermal cycling from tidal heating during lunar magma ocean crystallization caused crystals to coarsen, leading to efficient crystal-liquid separation.

  7. Liquid Crystal Microlens Using Nanoparticle-Induced Vertical Alignment

    Directory of Open Access Journals (Sweden)

    Shug-June Hwang

    2015-01-01

    Full Text Available The nanoparticle-induced vertical alignment (NIVA of the nematic liquid crystals (LC is applied to achieve an adaptive flat LC microlens with hybrid-aligned nematic (HAN mode by dropping polyhedral oligomeric silsesquioxane (POSS nanoparticle solution on a homogeneous alignment layer. The vertical alignment induced by the POSS nanoparticles resulted in the formation of a hybrid-aligned LC layer with concentric nonuniform distribution of the refractive index in the planar LC cell, which subsequently played the role of the lens, even in the absence of any applied voltages. The dimensions of the concentric HAN structure significantly depend on the volume of the microdroplet and the POSS concentration. The focus effect of this flat microlens was observed while electrically controlling its focal length using the applied voltages from −50 mm to −90 mm.

  8. Measuring liquid crystal anchoring energy strength by spectroscopic ellipsometry

    Science.gov (United States)

    Marino, A.; Tkachenko, V.; Santamato, E.; Bennis, N.; Quintana, X.; Otón, J. M.; Abbate, G.

    2010-04-01

    We describe an experimental procedure for accurate measurement of anchoring energy strength of liquid crystal cells. This technique is based on the possibility of gathering a large amount of very precise data about the linear optical response of the cell in different experimental conditions, using spectroscopic ellipsometry. Then, a careful data analysis exploiting data inversion method, supplemented by simulations from the elastic theory, is able to provide the searched information. The technique has been applied to vertical aligned nematic cells, chosen for its widespread use in the present display market. The results obtained in this particular case together with a thorough comparison with existing alternative techniques, suggest that our technique can be an optimum candidate for the industrial implementation of such measurement. A particular example is fully worked out, giving a result with a precision of 1.5% and an accuracy of 10%.

  9. Relaxation Dynamics of Spatiotemporal Chaos in the Nematic Liquid Crystal

    Science.gov (United States)

    Nugroho, Fahrudin; Ueki, Tatsuhiro; Hidaka, Yoshiki; Kai, Shoichi

    2011-11-01

    We are working on the electroconvection of nematic liquid crystals, in which a kind of spatiotemporal chaos called as a soft-mode turbulence (SMT) is observed. The SMT is caused by the nonlinear interaction between the convective modes and the Nambu--Goldstone (NG) modes. By applying an external magnetic field H, the NG mode is suppressed and an ordered pattern can be observed. By removing the suppression effect the ordered state relax to its original SMT pattern. We revealed two types of instability govern the relaxation process: the zigzag instability and the free rotation of wavevector q(r). This work is partially supported by Grant-in-Aid for Scientific Research (Nos. 20111003, 21340110, and 21540391) from the Ministry of Education, Culture, Sport, Science, and Technology of Japan and the Japan Society for the Promotion of Science (JSPS).

  10. Emerging Applications of Liquid Crystals Based on Nanotechnology

    Directory of Open Access Journals (Sweden)

    Jung Inn Sohn

    2014-03-01

    Full Text Available Diverse functionalities of liquid crystals (LCs offer enormous opportunities for their potential use in advanced mobile and smart displays, as well as novel non-display applications. Here, we present snapshots of the research carried out on emerging applications of LCs ranging from electronics to holography and self-powered systems. In addition, we will show our recent results focused on the development of new LC applications, such as programmable transistors, a transparent and active-type two-dimensional optical array and self-powered display systems based on LCs, and will briefly discuss their novel concepts and basic operating principles. Our research will give insights not only into comprehensively understanding technical and scientific applications of LCs, but also developing new discoveries of other LC-based devices.

  11. Soft memory in a ferroelectric nanoparticle-doped liquid crystal

    Science.gov (United States)

    Basu, Rajratan

    2014-02-01

    A small quantity of BaTiO3 ferroelectric nanoparticles (FNP) was doped in a liquid crystal (LC), and the LC + FNP hybrid was found to exhibit a nonvolatile electromechanical memory effect in the isotropic phase. The permanent dipole moment of the FNPs causes the LC molecule to form short-range pseudonematic domains surrounding the FNPs. The FNP-induced short-range orders become more prominent in the isotropic phase when the global nematic order is absent. These short-range domains, being anisotropic in nature, interact with an external electric field, exhibiting a Fréedericksz-type transition. When the field is turned off, these domains stay oriented, showing a hysteresis effect due to the absence of any long-range order and restoring forces in the isotropic phase. The hysteresis graph for this memory effect shows a significant pretransitional behavior on approaching the nematic phase from the isotropic phase.

  12. Control of nanoparticle self-assemblies using distorted liquid crystals

    Science.gov (United States)

    Lacaze, Emmanuelle; Coursault, Delphine

    This chapter concerns the structure and the optical properties of nanoparticle (NP)/liquid crystal (LC) composites in the presence of LC distortion. After a first description of the general behaviour of NPs at the proximity of distorted LC areas, the first section of the chapter discusses the stabilization of the LC phases, characterized by the presence of topological defects in presence of NPs. The assemblies of NPs induced by distorted LC films is addressed in the second section. The last section then extensively develops the structure and optical properties of NP assemblies created within topological defects. Specific localisation and orientations of the NPs will be discussed, but also possible control of the size and shape of the NP assemblies, together with control of the distances between NPs in the assemblies, leading to original optical properties of the composites as far as uorescent or gold NPs are concerned.

  13. Electrothermo-optical effect in liquid crystals and its applications

    Science.gov (United States)

    Hsiao, Yu-Cheng; Lee, Wei

    2017-02-01

    Electro-optical effects in liquid crystals (LCs) have been widely utilized in many optical components and photonic devices, thanks to the anisotropic media that can be easily manipulated by an electric field to modulate the light. In general, dielectric heating in LC applications is negligible because their orientational dielectric relaxations occur at high frequencies. Here we focus on a dual-frequency LC characterized by its much lower relaxation frequency. The fieldinduced heat strongly affects the LC ordering and optical properties. The electrothermo-optical effect reveals an unusual behavior compared with the well-known electro-optical effect in regular LCs. Based on the electrothermo-optical effect, some applications such as optical modulators or tunable optical shutters are demonstrated.

  14. Carbon nanotubes in thermotropic low molar mass liquid crystals

    Science.gov (United States)

    Schymura, Stefan; Park, Ji Hyun; Dierking, Ingo; Scalia, Giusy

    Carbon nanotubes constitute a highly anisotropic form of carbon with outstanding mechanical, thermal and electrical properties. Their dispersion and organization are important but challenging and this chapter describes the advantages of using thermotropic liquid crystals as host for nanotube dispersion and ordering. The self organization of LCs is an attractive way to manipulate nanoparticles such as carbon nanotubes or graphene akes. Compared to standard carbon nanotube composites (e.g. with disordered polymer hosts) the introduction of the nanotubes into an LC allows not only the transfer of the outstanding nanotube properties to the oscopic phase, providing strength and conductivity, but these properties also become anisotropic, following the transfer of the orientational order from the LC to the CNTs...

  15. Fingerprint sensor using a polymer dispersed liquid crystal holographic lens.

    Science.gov (United States)

    Jie, Ying; Jihong, Zheng

    2010-09-01

    We used a polymer dispersed liquid crystal material holographic lens in a fingerprint sensor, which reduced the total size of the sensor and improved image quality. The beam carrying fingerprint information was diffracted by the holographic lens and converged onto the complementary metal-oxide semiconductor image sensor directly, which omitted the traditional lens or fiber taper. The phenomenon that the image quality is poor when the finger is too dry or wet was explained based on the evanescent wave theory. The total size of the device was 50 mm x 25 mm x 30 mm. The fingerprint image had a contrast of 250:1 and a resolution of 800 dots/in.

  16. Flexible Polymer Dispersed Liquid Crystal Module with Graphene Electrode.

    Science.gov (United States)

    Liu, Feng; Wang, Guoping; Pal, Kaushik; Zhan, Bihong; Liu, Sheng; Wen, Ding; Ye, Shuangli

    2015-12-01

    Flexible polymer dispersed liquid crystal (PDLC) module based on graphene electrode was presented in this article. We also investigated electromechanical, as well as electro-optical properties of PDLC module with graphene electrodes. Compared to the ITO electrodes, graphene electrodes exhibits higher light transmittance and more stable electromechanical property of under bend test. Due to the excellent mechanical property of graphene electrodes, it is expected that the flexibility of PDLC module could be further enhanced. Meanwhile, with the integration of graphene as the driving electrodes, the threshold voltage V(th) and saturation voltage V(sat) of PDLC module have small change, while the on-state transmittance T(on) is increased by 5%, that may attribute to the high transmittance of the graphene.

  17. Transparent laser damage resistant nematic liquid crystal cell "LCNP3"

    Science.gov (United States)

    Raszewski, Z.; Piecek, W.; Jaroszewicz, L.; Dąbrowski, R.; Nowinowski-Kruszelnicki, E.; Soms, L.; Olifierczuk, M.; Kędzierski, J.; Morawiak, P.; Mazur, R.; Miszczyk, E.; Mrukiewicz, M.; Kowiorski, K.

    2014-09-01

    There exists the problem in diagnostics of dense plasma (so-called Thomson diagnostics). For this purpose the plasma is illuminated by series of high energy laser pulses. The energy of each separate pulse is as large as 3 J, so it is impossible to generate a burst of such pulses by a single laser. In this situation, the pulses are generated by several independent lasers operating sequentially, and these pulses are to be directed along the same optical path. To form an optical path with λ = 1.064 μm and absolute value of the laser pulse energy of 3 J, a special refractive index matched twisted Nematic Liquid Crystal Cell of type LCNP3, with switching on time τON smaller than 3 μs was applied.

  18. Interaction between lyotropic chromonic liquid crystals and polymers

    Science.gov (United States)

    Yao, Xuxia; Park, Jung; Srinivasarao, Mohan

    2010-03-01

    Lyotropic chromonic liquid crystals (LCLCs) consist of various dyes, drugs, etc., so their importance is self-evident. The interaction of chromonic molecules and polymers is involved in their real applications, such as the dyeing process of fibers, textiles and food, and the functionalization of drugs in vivo. In our research, polymer dispersed LCLC droplets and polymer coated LCLC cells have been fabricated. Effect of interaction was observed by optical texture of LCLCs, as the different polymers induce different director configuration of LCLCs. A textile dye-Benzopurpurine 4B, food dye-Sunset Yellow FCF, and drug-Disodium Cromoglycate mixed with water soluble polymers, proteins and textile polymers have been all studied and compared.

  19. Some specificities of wetting by cyanobiphenyl liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Delabre, U; Richard, C; Cazabat, A M, E-mail: cazabat@lps.ens.f [Laboratoire de Physique Statistique, Ecole Normale Superieure, Universite Pierre et Marie Curie, CNRS, 24 rue Lhomond, 75231 Paris Cedex 05 (France)

    2009-11-18

    The present paper provides an up to date restatement of the wetting behaviour of the series of cyanobiphenyl liquid crystals (LCs) on usual substrates, i.e. oxidized silicon wafers, water and glycerol, at both the macroscopic and microscopic scale, in the nematic range of temperature. We show that on water the systems are close to a wetting transition, especially 5CB and 7CB. In that case, the wetting behaviour is controlled by the presence of impurities. On a mesoscopic scale, we observe for all our (thin LC film-substrate) systems an identical, complex, but well defined general scenario, not accounted for by the available models. In the last part, we present a study on line tension which results from the specific organization of LCs at the edge of the nematic film. We report preliminary results on two-dimensional film coalescence where this line tension plays a major role.

  20. Curling Liquid Crystal Microswimmers: A Cascade of Spontaneous Symmetry Breaking.

    Science.gov (United States)

    Krüger, Carsten; Klös, Gunnar; Bahr, Christian; Maass, Corinna C

    2016-07-22

    We report curling self-propulsion in aqueous emulsions of common mesogenic compounds. Nematic liquid crystal droplets self-propel in a surfactant solution with concentrations above the critical micelle concentration while undergoing micellar solubilization [Herminghaus et al., Soft Matter 10, 7008 (2014)]. We analyzed trajectories both in a Hele-Shaw geometry and in a 3D setup at variable buoyancy. The coupling between the nematic director field and the convective flow inside the droplet leads to a second symmetry breaking which gives rise to curling motion in 2D. This is demonstrated through a reversible transition to nonhelical persistent swimming by heating to the isotropic phase. Furthermore, autochemotaxis can spontaneously break the inversion symmetry, leading to helical trajectories in 3D.

  1. Transitions through critical temperatures in nematic liquid crystals

    KAUST Repository

    Majumdar, Apala

    2013-08-06

    We obtain estimates for critical nematic liquid crystal (LC) temperatures under the action of a slowly varying temperature-dependent control variable. We show that biaxiality has a negligible effect within our model and that these delay estimates are well described by a purely uniaxial model. The static theory predicts two critical temperatures: the supercooling temperature below which the isotropic phase loses stability and the superheating temperature above which the ordered nematic states do not exist. In contrast to the static problem, the isotropic phase exhibits a memory effect below the supercooling temperature in the dynamic framework. This delayed loss of stability is independent of the rate of change of temperature and depends purely on the initial value of the temperature. We also show how our results can be used to improve estimates for LC material constants. © 2013 American Physical Society.

  2. Molecular engineering of chiral colloidal liquid crystals using DNA origami

    Science.gov (United States)

    Siavashpouri, Mahsa; Wachauf, Christian H.; Zakhary, Mark J.; Praetorius, Florian; Dietz, Hendrik; Dogic, Zvonimir

    2017-08-01

    Establishing precise control over the shape and the interactions of the microscopic building blocks is essential for design of macroscopic soft materials with novel structural, optical and mechanical properties. Here, we demonstrate robust assembly of DNA origami filaments into cholesteric liquid crystals, one-dimensional supramolecular twisted ribbons and two-dimensional colloidal membranes. The exquisite control afforded by the DNA origami technology establishes a quantitative relationship between the microscopic filament structure and the macroscopic cholesteric pitch. Furthermore, it also enables robust assembly of one-dimensional twisted ribbons, which behave as effective supramolecular polymers whose structure and elastic properties can be precisely tuned by controlling the geometry of the elemental building blocks. Our results demonstrate the potential synergy between DNA origami technology and colloidal science, in which the former allows for rapid and robust synthesis of complex particles, and the latter can be used to assemble such particles into bulk materials.

  3. Cholesteric Liquid Crystal Based Reflex Color Reflective Displays

    Science.gov (United States)

    Khan, Asad

    2012-02-01

    Bistable color cholesteric liquid crystal displays are unique LCDs that exhibit high reflectivity, good contrast, extremely low power operation, and are amenable to versatile roll-to-roll manufacturing. The display technology, now branded as Reflex has been in commercialized products since 1996. It has been the subject of extensive research and development globally by a variety of parties in both academic and industrial settings. Today, the display technology is in volume production for applications such as dedicated eWriters (Boogie Board), full color electronic skins (eSkin), and displays for smart cards. The flexibility comes from polymerization induced phase separation using unique materials unparalleled in any other display technology. The blend of monomers, polymers, cross linkers, and other components along with nematic liquid crystals and chiral dopants is created and processed in such ways so as to enable highly efficient manufactrable displays using ultra thin plastic substrates -- often as thin as 50μm. Other significant aspects include full color by stacking or spatial separation, night vision capability, ultra high resolution, as well as active matrix capabilities. Of particular note is the stacking approach of Reflex based displays to show full color. This approach for reflective color displays is unique to this technology. Owing to high transparency in wavelength bands outside the selective reflection band, three primarily color layers can be stacked on top of each other and reflect without interfering with other layers. This highly surprising architecture enables the highest reflectivity of any other reflective electronic color display technology. The optics, architecture, electro-topics, and process techniques will be discussed. This presentation will focus on the physics of the core technology and color, it's evolution from rigid glass based displays to flexible displays, development of products from the paradigm shifting concepts to consumer

  4. Electro-optical switching of liquid crystals of graphene oxide

    Science.gov (United States)

    Song, Jang-Kun

    Electric field effects on aqueous graphene-oxide (GO) dispersions are reviewed in this chapter. In isotropic and biphasic regimes of GO dispersions, in which the inter-particle friction is low, GO particles sensitively respond to the application of electric field, producing field-induced optical birefringence. The electro-optical sensitivity dramatically decreases as the phase transits to the nematic phase; the increasing inter-particle friction hinders the rotational switching of GO particles. The corresponding Kerr coefficient reaches the maximum near the isotropic to biphasic transition concentration, at which the Kerr coefficient is found be c.a. 1:8 · 10-5 mV-2, the highest value ever reported in all Kerr materials. The exceptionally large Kerr effect arises from the Maxwell- Wagner polarization of GO particles with an extremely large aspect ratio and a thick electrical double layer (EDL). The polarization sensitively depends on the ratio of surface and bulk conductivities in dispersions. As a result, low ion concentration in bulk solvent is highly required to achieve a quality electro-optical switching in GO dispersions. Spontaneous vinylogous carboxylic reaction in GO particles produces H+ ions, resulting in spontaneous degradation of electro-optical response with time, hence the removal of residual ions by using a centrifuge cleaning process significantly improves the electro-optical sensitivity. GO particle size is another important parameter for the Kerr coefficient and the response time. The best performance is observed in a GO dispersion with c.a. 0.5 μm mean size. Dielectrophoretic migration of GO particles can be also used to manipulate GO particles in solution. Using these unique features of GO dispersions, one can fabricate GO liquid crystal devices similar to conventional liquid crystal displays; the large Kerr effect allows fabricating a low power device working at extremely low electric fields.

  5. Active liquid-crystal deflector and lens with Fresnel structure

    Science.gov (United States)

    Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

    2017-02-01

    A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

  6. New liquid crystals in the series of 1, 3, 5-triazine compounds ...

    African Journals Online (AJOL)

    New liquid crystals in the series of 1, 3, 5-triazine compounds containing azobenzene at the peripheral arms. ... Bayero Journal of Pure and Applied Sciences ... Novel liquid crystal materials whose molecular structures consist of disc-like 1,3,5-triazine unit as a central core and three rod-like azobenzenes as the peripheral ...

  7. Liquid Crystal Phases of Colloidal Platelets and their Use as Nanocomposite Templates

    NARCIS (Netherlands)

    Mourad, M.C.D.|info:eu-repo/dai/nl/304837563

    2009-01-01

    This thesis explores the gelation and liquid crystal phase behavior of colloidal dispersions of platelike particles as well as the use of such dispersions for the generation of nanocomposites. We report on the sol-gel, sol-glass and liquid crystal phase transitions of positively charged colloidal

  8. Analysis of thermoplastic polyimide + polymer liquid crystal blends

    Science.gov (United States)

    Gopalanarayanan, Bhaskar

    Thermoplastic polyimides (TPIs) exhibit high glass transition temperatures (Tsbgs), which make them useful in high performance applications. Amorphous and semicrystalline TPIs show sub-Tsbg relaxations, which can aid in improving strength characteristics through energy absorption. The alpha relaxation of both types of TPIs indicates a cooperative nature. The semicrystalline TPI shows thermo-irreversible cold crystallization phenomenon. The polymer liquid crystal (PLC) used in the blends is thermotropic and with longitudinal molecular structure. The small heat capacity change (Delta Csb{p}) associated with the glass transition indicates the PLC to be rigid rod in nature. The PLC shows a small endotherm associated with the melting. The addition of PLC to the semicrystalline TPI does not significantly affect the Tsbg or the melting point (Tsbm). The cold crystallization temperature (Tsbc) increases with the addition of the PLC, indicating channeling phenomenon. The addition of PLC also causes a negative deviation of the Delta Csb{p}, which is another evidence for channeling. The TPI, PLC and their blends show high thermal stability. The semicrystalline TPI absorbs moisture; this effect decreases with the addition of the PLC. The absorbed moisture does not show any effect on the degradation. The addition of PLC beyond 30 wt.% does not result in an improvement of properties. The amorphous TPI + PLC blends also show the negative deviation of Delta Csb{p} from linearity with composition. The addition of PLC causes a decrease in the thermal conductivity in the transverse direction to the PLC orientation. The thermomechanical analysis indicates isotropic expansivity for the amorphous TPI and a small anisotropy for the semicrystalline TPI. The PLC shows large anisotropy in expansivity. Even 5 wt.% concentration of PLC in the blend induces considerable anisotropy in the expansivity. Thus, blends show controllable expansivity through PLC concentration. Amorphous TPI + PLC

  9. Zigzag line defects and manipulation of colloids in a nematic liquid crystal in microwrinkle grooves.

    Science.gov (United States)

    Ohzono, Takuya; Fukuda, Jun-ichi

    2012-02-28

    Spatially confined liquid crystals exhibit non-uniform alignment, often accompanied by self-organised topological defects of non-trivial shape in response to imposed boundary conditions and geometry. Here we show that a nematic liquid crystal, when confined in a sinusoidal microwrinkle groove, exhibits a new periodic arrangement of twist deformations and a zigzag line defect. This periodic ordering results from the inherent liquid crystal elastic anisotropy and the antagonistic boundary conditions at the flat liquid crystal-air and the curved liquid crystal-groove interfaces. The periodic structure can be tuned by controlling the groove geometry and the molecular chirality, which demonstrates the importance of boundary conditions and introduced asymmetry for the engineering of topological defects. Moreover, the kinks in the zigzag defects can trap small particles, which may afford a new method for manipulation of colloids. Our system, which uses easily fabricated microwrinkle grooves, provides a new microfabrication method based on the arrangement of controllable defects.

  10. Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

    Directory of Open Access Journals (Sweden)

    Amanda García-García

    2016-06-01

    Full Text Available Single-wall carbon nanotubes (SWCNT are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules.

  11. Liquid Crystal Formation from Sunflower Oil: Long Term Stability Studies.

    Science.gov (United States)

    da Rocha-Filho, Pedro Alves; Maruno, Mônica; Ferrari, Márcio; Topan, José Fernando

    2016-06-09

    The Brazilian biodiversity offers a multiplicity of raw materials with great potential in cosmetics industry applications. Some vegetable oils and fatty esters increase skin hydration by occlusivity, keeping the skin hydrated and with a shiny appearance. Sunflower (Helianthus annus L.) oil is widely employed in cosmetic emulsions in the form of soaps, creams, moisturizers and skin cleansers due to the presence of polyphenols and its high vitamin E content. Liquid crystals are systems with many applications in both pharmaceutical and cosmetic formulations and are easily detected by microscopy under polarized light due to their birefringence properties. The aim of this research was to develop emulsions from natural sunflower oil for topical uses. Sunflower oil (75.0% w/w) was combined with liquid vaseline (25.0% w/w) employing a natural self-emulsifying base (SEB) derivative. The high temperature of the emulsification process did not influence the antioxidant properties of sunflower oil. Fatty esters were added to cosmetic formulations and extended stability tests were performed to characterize the emulsions. Fatty esters like cetyl palmitate and cetyl ester increase the formation of anisotropic structures. O/W emulsions showed acidic pH values and pseudoplastic behavior. The presence of a lamellar phase was observed after a period of 90 days under different storage conditions.

  12. NMR studies of molecules in liquid crystals and graphite

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, M.E.

    1992-06-01

    NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.

  13. Liquid Crystal Formation from Sunflower Oil: Long Term Stability Studies

    Directory of Open Access Journals (Sweden)

    Pedro Alves da Rocha-Filho

    2016-06-01

    Full Text Available The Brazilian biodiversity offers a multiplicity of raw materials with great potential in cosmetics industry applications. Some vegetable oils and fatty esters increase skin hydration by occlusivity, keeping the skin hydrated and with a shiny appearance. Sunflower (Helianthus annus L. oil is widely employed in cosmetic emulsions in the form of soaps, creams, moisturizers and skin cleansers due to the presence of polyphenols and its high vitamin E content. Liquid crystals are systems with many applications in both pharmaceutical and cosmetic formulations and are easily detected by microscopy under polarized light due to their birefringence properties. The aim of this research was to develop emulsions from natural sunflower oil for topical uses. Sunflower oil (75.0% w/w was combined with liquid vaseline (25.0% w/w employing a natural self-emulsifying base (SEB derivative. The high temperature of the emulsification process did not influence the antioxidant properties of sunflower oil. Fatty esters were added to cosmetic formulations and extended stability tests were performed to characterize the emulsions. Fatty esters like cetyl palmitate and cetyl ester increase the formation of anisotropic structures. O/W emulsions showed acidic pH values and pseudoplastic behavior. The presence of a lamellar phase was observed after a period of 90 days under different storage conditions.

  14. Shapes and singularities in triatic liquid-crystal vesicles

    Science.gov (United States)

    Bowick, Mark J.; Manyuhina, O. V.; Serafin, F.

    2017-01-01

    Determining the equilibrium configuration and shape of curved two-dimensional films with (generalized) liquid-crystalline order is a difficult infinite-dimensional problem of direct relevance to the study of generalized polymersomes, soft matter and the fascinating problem of understanding the origin and formation of shape (morphogenesis). The symmetry of the free energy of the LC film being considered and the topology of the surface to be determined often requires that the equilibrium configuration possesses singular structures in the form of topological defects such as disclinations for nematic films. The precise number and type of defect plays a fundamental role in restricting the space of possible equilibrium shapes. Flexible closed vesicles with spherical topology and nematic or smectic order, for example, inevitably possess four elementary strength +1/2 disclination defects positioned at the four vertices of a tetrahedral shell. Here we address the problem of determining the equilibrium shape of flexible vesicles with generalized liquid-crystalline order. The order parameter in these cases is an element of S^1/Zp , for any positive integer p. We will focus on the case p =3 , known as triatic liquid crystals (LCs). We construct the appropriate order parameter for triatics and find the associated free energy. We then describe the structure of the elementary defects of strength +1/3 in flat space. Finally, we prove that sufficiently floppy triatic vesicles with the topology of the 2-sphere equilibrate to octahedral shells with strength +1/3 defects at each of the six vertices, independently of the scale.

  15. Antivitamin B12 Inhibition of the Human B12 -Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate.

    Science.gov (United States)

    Ruetz, Markus; Shanmuganathan, Aranganathan; Gherasim, Carmen; Karasik, Agnes; Salchner, Robert; Kieninger, Christoph; Wurst, Klaus; Banerjee, Ruma; Koutmos, Markos; Kräutler, Bernhard

    2017-06-19

    B12 antivitamins are important and robust tools for investigating the biological roles of vitamin B12 . Here, the potential antivitamin B12 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co-C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B12 -processing enzyme CblC with high affinity (KD =130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B12 and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this enzyme. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Dielectric properties and molecular motions of liquid crystal molecules in 4-(2-methylbytylphenyl 4-(4-octylphenylbenzoate liquid crystal having blue phase (CE8

    Directory of Open Access Journals (Sweden)

    Otowski W.

    2015-06-01

    Full Text Available Blue phase liquid crystals exhibit unique properties which are used in the new type of display. A blue-phase liquid crystal display was first presented commercially by Samsung in 2007. The blue-phase-three-color pixel display eliminates the need for color filters. This type of display uses blue-phase multi-component liquid crystal. Considering the one-component systems, it turns out that they are stable only in a very narrow range of temperatures between the isotropic and the chiral nematic phase (about 1 K. In 2005, a wide temperature range BP multi-component system was reported by researchers from the University of Cambridge. There are still several unsolved problems left. One of them is chemical stability and reliability. Therefore, the knowledge of molecular dynamics of blue phase liquid crystal is a prerequisite for understanding of blue-phase multi-component system. Understanding the molecular dynamics of a single component liquid-crystalline blue phase system can facilitate the solution of these problems. We present the molecular dynamics investigation of 4-(2-methylbytylphenyl 4-(4-octylphenylbenzoate (CE8, which may be a good candidate to form materials suitable for blue-phase liquid crystal displays.

  17. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    van Emmerik, P.T.; Smolders, C.A.

    1972-01-01

    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  18. Properties and stability of a liquid crystal form of cyclosporine-the first reported naturally occurring peptide that exists as a thermotropic liquid crystal.

    Science.gov (United States)

    Lechuga-Ballesteros, David; Abdul-Fattah, Ahmad; Stevenson, Cynthia L; Bennett, David B

    2003-09-01

    A new solid-state form of cyclosporine produced by spray-drying exhibited characteristics consistent with a liquid crystal. No sharp diffraction peaks were observed by powder X-ray diffraction; however, analysis by both small-angle X-ray diffraction (SAXR) and microscopic under polarized light (PLM) confirmed the existence of two-dimensional ordered liquid crystal. Hot stage microscopy revealed a solid-to-liquid transition, in the range of 118 to 125 degrees C. Moreover, the solid-to-liquid transition showed frequency dependence by dielectric analysis (DEA), and was coincidental with a stepwise heat capacity change measured by differential scanning Calorimetry (DSC). The two-dimensional order was maintained above the solid-to-liquid transition temperature indicated by low-angle diffraction by SAXR and birefringence by PLM. However, birefringence was lost at temperatures above 170 degrees C, indicating the conversion of the liquid crystal into an isotropic liquid. In situ annealing experiments, by DSC, revealed the presence of an endotherm, unexplained by either a phase transition or solvent loss, and it is believed to be the result of a structural rearrangement that has no impact on the macroscopic properties of the material. Spray-dried cyclosporine at room temperature is therefore a frozen thermotropic liquid crystal due to the presence of two-dimensional order and the lack of substantial residual solvent. This is, to our knowledge, the first report of the existence of a thermotropic liquid crystal of a naturally occurring peptide. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:1821-1831, 2003

  19. Synthesis, crystal structure, EPR properties, and anti-convulsant activities of binuclear and mononuclear 1,10-phenanthroline and salicylate ternary copper(II) complexes.

    Science.gov (United States)

    Lemoine, Pascale; Viossat, Bernard; Morgant, Georges; Greenaway, Frederick T; Tomas, Alain; Dung, Nguyen Huy; Sorenson, John R J

    2002-04-10

    Two ternary Cu(II) complexes of 1,10-phenanthroline (phen) and singly (Hsal(-)) or dideprotonated (sal(2-)) salicylate ligands were synthesized, their X-ray crystal structure and electron paramagnetic resonance spectral characteristics determined, and evaluated for anti-convulsant activities in the maximal electroshock (MES) and Metrazol models of seizure and Rotorod toxicity. The X-ray crystal structure of [bis(1,10-phenanthroline)-mu-bis(salicylato-O,O')dicopper(II)] dihydrate, 1, ([Cu(II)(2)(phen)(2)(sal)(2)].2[H(2)O]), shows it to be binuclear. This dimer consists of two centrosymmetrically related pseudo-five coordinate Cu(II) atoms 3.242(2) A apart and bridged by two dideprotonated salicylate ligands. The X-ray crystal structure of [bis(1,10-phenanthroline)(salicylato)copper(II)][salicylate] monohydrate, 2, ([Cu(II)(phen)(2)(Hsal)](+)[Hsal](-)[H(2)O]), shows it to be mononuclear. This complex cation exhibits a highly irregular distorted square pyramidal geometry about the Cu(II) atom, (4+1+1*). Each salicylate is singly deprotonated and one of them is ligand bonded in an asymmetric chelating mode. EPR results for 2 indicate that in concentrated DMF solution phen remains bonded to copper but salicylate is likely monodentate in contrast to the situation for 1. However, in dilute DMF solution, both 1 and 2 form the same species, which accounts for the similarity in anti-convulsant activity of the two compounds. Both 1 and 2 were found to be effective in preventing MES-induced seizures and ineffective in preventing Metrazol-induced seizures. Rotorod toxicity, consistent with central nervous system depression, paralleled the observed anti-convulsant activity. It is suggested that the observed anti-convulsant activity is consistent with central nervous system depression as a physiological mechanism in overcoming MES-induced seizures due to MES-induced brain inflammatory disease.

  20. Liquid-crystal science from 1888 to 1922: building a revolution.

    Science.gov (United States)

    Mitov, Michel

    2014-05-19

    The saga of liquid crystals started with their discovery in 1888 by the botanist Friedrich Reinitzer, who unexpectedly observed "two melting points" for crystals extracted from the root of a carrot. At the end of the nineteenth century, most scientists did not believe in the existence of "liquid crystals" as promoted by the crystallographer Otto Lehmann. The controversies were very vivid; to the point that the recognition of mesomorphic states of matter by the scientific community required more than two decades. In the end, liquid crystals have changed our vision of matter by shattering the three-state paradigm. Since the mid-1970s, liquid crystals have revolutionized the worldwide information-display industry and now play a host of key roles in various technologies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Active Janus Particles at Interfaces of Liquid Crystals.

    Science.gov (United States)

    Mangal, Rahul; Nayani, Karthik; Kim, Young-Ki; Bukusoglu, Emre; Córdova-Figueroa, Ubaldo M; Abbott, Nicholas L

    2017-10-17

    We report an investigation of the active motion of silica-palladium Janus particles (JPs) adsorbed at interfaces formed between nematic liquid crystals (LCs) and aqueous phases containing hydrogen peroxide (H2O2). In comparison to isotropic oil-aqueous interfaces, we observe the elasticity and anisotropic viscosity of the nematic phase to change qualitatively the active motion of the JPs at the LC interfaces. Although contact line pinning on the surface of the JPs is observed to restrict out-of-plane rotational diffusion of the JPs at LC interfaces, orientational anchoring of nematic LCs on the silica (planar) and palladium (homeotropic) hemispheres biases JP in-plane orientations to generate active motion almost exclusively along the director of the LC at low concentrations of H2O2 (0.5 wt %). In contrast, displacements perpendicular to the director exhibit the characteristics of Brownian diffusion. At higher concentrations of H2O2 (1-3 wt %), we observe an increasing population of JPs propelled parallel and perpendicular to the LC director in a manner consistent with active motion. In addition, under these conditions, we also observe a subpopulation of JPs (approximately 10%) that exhibit active motion exclusively perpendicular to the LC director. These results are discussed in light of independent measurements of the distribution of azimuthal orientations of the JPs at the LC interfaces and calculations of the elastic energies that bias JP orientations. We also contrast our observations at LC interfaces to past studies of self-propulsion of particles within and at the interfaces of isotropic liquids.

  2. Optical manipulation of self-aligned graphene flakes in liquid crystals.

    Science.gov (United States)

    Twombly, Christopher W; Evans, Julian S; Smalyukh, Ivan I

    2013-01-14

    Graphene recently emerged as a new two-dimensional material platform with unique optical, thermal and electronic properties. Single- or few-atom-thick graphene flakes can potentially be utilized to form structured bulk composites that further enrich these properties and enable a broad range of new applications. Here we describe optical manipulation of self-aligned colloidal graphene flakes in thermotropic liquid crystals of nematic and cholesteric types. Three-dimensional rotational and translational manipulation of graphene flakes by means of holographic optical tweezers allows for non-contact spatial patterning of graphene, control of liquid crystal defects, and low-power optical realignment of the liquid crystal director using these flakes. Potential applications include optically- and electrically-controlled reconfigurable liquid crystalline dispersions of spontaneously aligning colloidal graphene flakes and new electro-optic devices with graphene-based interconnected transparent electrodes at surfaces and in the bulk of liquid crystals.

  3. Nonmechanical Infrared Beam Steering Using Blue Addressed Quantum Dot Doped Liquid Crystal Grating

    Science.gov (United States)

    Wang, Xiangru; Huang, Xiaoping; Huang, Ziqiang; Wu, Liang; Shang, Jiyang; Qiu, Qi; Wu, Shuanghong

    2017-01-01

    We present a scheme of nonmechanical laser beam steering using ZnS/InP quantum dots doping nematic liquid crystal as the optical recording film. Because of its internal electric field generated by blue laser-induced charge carrier distribution, liquid crystal molecules are reoriented to form a phase grating which make the incident angle steer to the angle as we desire. Being a nonmechanical programmable laser beam steering, the anisotropy of the relative permittivity tensor and blue laser-induced electric carriers play a significant effect in determining the reorientable liquid crystal molecule and reconfigurable phase modulation of the gratings, that determines the steering angle and steering efficiency.

  4. Polarization properties of polymer-dispersed liquid-crystal film with small nematic droplets.

    Science.gov (United States)

    Lisinetskaya, Polina G; Konkolovich, Alexander A; Loiko, Valery A

    2009-06-10

    The polarization state of light transmitted through a polymer-dispersed liquid-crystal film with small, spherical, nonabsorbing, partially oriented nematic droplets is theoretically investigated. The model used is based on the effective medium approach. Scattering properties of a single droplet are described by the Rayleigh-Gans approximation. Propagation of coherent light is described within the framework of the Twersky theory. To describe the orientation of liquid-crystal molecules inside droplets and liquid-crystal droplets in a sample, the concept of multilevel order parameters is employed. Conditions for circular and linear polarization of the transmitted light are determined and investigated.

  5. Long-pitch cholesteric liquid crystals for display applications

    Science.gov (United States)

    Yoon, Tae-Hoon; Huh, Jae-Won; Yu, Byeong-Hun

    2014-02-01

    Cholesteric liquid crystals (CLCs) have been used for a reflective display because of their reflective nature in the planar state. In a reflective display, the planar and the focal-conic states are used for the bright state and the dark state, respectively. In this paper we introduce a long-pitch CLC device, in which a selective wavelength of the reflected light is shifted to infrared (IR) wavelengths by controlling the pitch. The planar state of a long-pitch CLC device is transparent over the entire visible wavelengths in the field-off state. Omni-directional achromatic reflection through light scattering in the focal-conic state can be achieved without a polarizer. Compared to conventional CLC cells that reflect the visible light in the planar state, a long-pitch CLC device has a longer pitch, of which the operating voltage for switching between the two state is much lower so that achromatic reflective displays and light shutters with low power consumption can be realized using long-pitch CLC devices. By coupling with a reflector, the light efficiency of a longpitch CLC cell in the focal-conic state can be enhanced, by which higher brightness can be obtained for application to reflective displays. A dye-doped long-pitch CLC device can be placed behind a transparent organic light-emitting diode display for use as a light shutter to block the ambient light.

  6. Electro-optic bistability in organosiloxane bimesogenic liquid crystals

    Science.gov (United States)

    Gardiner, D. J.; Davenport, C. J.; Newton, J.; Coles, H. J.

    2006-06-01

    In this paper we report the electro-optic characterization of two homologous series of low molar mass bimesogenic siloxane-containing liquid crystals. The materials used have two alkoxycyanobiphenyl mesogenic units with variable alkyl chain joined by a two- or five-siloxane moiety and all exhibit stable smectic A mesophases over wide temperature ranges (up to 100 °C wide). Due to their inherent ruggedness these materials have potential for use in polarizer-free, bistable, scattering display and storage devices. The bistable modes are at low and high frequencies. The low frequency mode (write) is a highly scattering focal conic texture resulting from electrohydrodynamic instabilities while the high frequency mode (erase) is a clear state due to dielectric reorientation of the material. Both modes are preserved upon removal of the applied electric field. We present threshold voltages as a function of temperature, frequency, and cell thickness and response times as a function of voltage for each of the bistable modes. We find reduced threshold voltages (5<=Vth<=12 V/μm) and response times that are strongly dependent on applied voltage (50 ms<=τ<=10 s). These operating conditions would suggest that these materials are particularly suitable for slow update, large area, low power information panels and displays.

  7. Micropatterning with a liquid crystal display (LCD) projector.

    Science.gov (United States)

    Itoga, Kazuyoshi; Kobayashi, Jun; Yamato, Masayuki; Okano, Teruo

    2014-01-01

    Photolithography has been applied to biological applications such as cell and protein micropatterning and the fabrication of microfluidic channels. However, the preparation of photomasks for projecting micropattern lighting images is often time consuming and costly. Therefore, we have developed maskless photolithography devices by modifying the optics of commercially available liquid crystal display (LCD) projectors from extended to reduced projection. The developed second and third devices produce practically a centimeter-scale micropattern by dividing an original large mask pattern into several patterns, which are individually and synchronously exposed to substrates with a motorized XY-stage, applying them to cell micropatterning and polydimethylsiloxane (PDMS) microfluidic device production. The first part of this chapter describes the developments of the maskless photolithography devices. The second part describes the exposure control system with a motorized XY-stage. The third part describes the applications of devices to cell micropatterning. The last part describes the application of the devices to the fabrication of the PDMS microfluidic channel. Maskless photolithography with an LCD projector has a large advantage with no requirement for a photomask. In particular, the maskless photolithography devices show a greater power by optimizing the conditions of pattern size and shape. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. History-Dependent Patterns in Randomly Perturbed Nematic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    A. Ranjkesh

    2013-01-01

    Full Text Available We study the characteristics of nematic structures in a randomly perturbed nematic liquid crystal (LC phase. We focus on the impact of the samples history on the universal behavior. The obtained results are of interest for every randomly perturbed system exhibiting a continuous symmetry-breaking phase transition. A semimicroscopic lattice simulation is used where the LC molecules are treated as cylindrically symmetric, rod-like objects interacting via a Lebwohl-Lasher (LL interaction. Pure LC systems exhibit a first order phase transition into the orientationally ordered nematic phase at T=Tc on lowering the temperature T. The orientational ordering of LC molecules is perturbed by the quenched, randomly distributed rod-like impurities of concentration p. Their orientation is randomly distributed, and they are coupled with the LC molecules via an LL-type interaction. Only concentrations below the percolation threshold are considered. The key macroscopic characteristics of perturbed LC structures in the symmetry-broken nematic phase are analyzed for two qualitatively different histories at T≪Tc. We demonstrate that, for a weak enough interaction among the LC molecules and impurities, qualitatively different history-dependent states could be obtained. These states could exhibit either short-range, quasi-long-range, or even long-range order.

  9. On the critical behaviour of two-dimensional liquid crystals

    Directory of Open Access Journals (Sweden)

    A.l. Fariñas-Sánchez

    2010-01-01

    Full Text Available The Lebwohl-Lasher (LL model is the traditional model used to describe the nematic-isotropic transition of real liquid crystals. In this paper, we develop a numerical study of the temperature behaviour and of finite-size scaling of the two-dimensional (2D LL-model. We discuss two possible scenarios. In the first one, the 2D LL-model presents a phase transition similar to the topological transition appearing in the 2D XY-model. In the second one, the 2D LL-model does not exhibit any critical transition, but its low temperature behaviour is rather characterized by a crossover from a disordered phase to an ordered phase at zero temperature. We realize and discuss various comparisons with the 2D XY-model and the 2D Heisenberg model. Having added finite-size scaling behaviour of the order parameter and conformal mapping of order parameter profile to previous studies, we analyze the critical scaling of the probability distribution function, hyperscaling relations and stiffness order parameter and conclude that the second scenario (no critical transition is the most plausible.

  10. On the theory and simulation of confined liquid crystals

    CERN Document Server

    Andrienko, D

    2001-01-01

    cylindrical symmetry of the core is broken and two defects of strength +1/2 may be resolved. We use molecular dynamics to study the ordering of a nematic liquid crystal around a spherical particle or droplet. We observe three defect structures for different particle sizes: a quadrupolar one with a ring defect surrounding the particle in the equatorial plane; a dipolar one with a satellite defect at the north or south pole; and a transitional, non-equatorial, ring defect. By studying density and order-parameter maps, we are able to examine behavior near the particle surface, and in the disclination core region, where the elastic theory is inapplicable. We present the results of molecular dynamics simulations of the topological defects that appear around an elongated colloidal particle. We also study the force and the torque on the particle suspended in the bulk of the nematic mesophase and modification of this torque when the particle is close to the cell substrate. In this thesis, we investigate several aspec...

  11. Copper and liquid crystal polymer bonding towards lead sensing

    Science.gov (United States)

    Redhwan, Taufique Z.; Alam, Arif U.; Haddara, Yaser M.; Howlader, Matiar M. R.

    2018-02-01

    Lead (Pb) is a highly toxic and carcinogenic heavy metal causing adverse impacts on environment and human health, thus requiring its careful monitoring. In this work, we demonstrate the integration of copper (Cu) film-based electrodes toward Pb sensing. For this, we developed a direct bonding method for Cu thin film and liquid crystal polymer (LCP) substrate using oxygen plasma treatment followed by contact and heat at 230 °C. The oxygen plasma activation forms hydroxyl groups (OH‑) on Cu and LCP. The activated surfaces further adsorb water molecules when exposed to clean room air during contact. After contact, hydrogen bonds are formed between the OH‑ groups. The interfacial water is removed when the contacted films are heated, leading to shrinkage of OH‑ chain. This results in an intermediate oxide layer linking the Cu and C sites of Cu and LCP respectively. A strong adhesion (670 N·m‑1) is obtained between Cu/LCP that may offer prolonged use of the electrode without delamination in wet sensing applications. Anodic stripping voltammetry of Pb using Cu thin film electrode shows a stronger current peak than sputtered Cu electrode, which implies the significance of the direct bonding approach to integrate thin films. We also studied the electrochemical impedance that will enable modeling of integrated environmental sensors for on-site monitoring of heavy metals.

  12. Smart windows based on cholesteric liquid crystals (Conference Presentation)

    Science.gov (United States)

    Khandelwal, Hitesh; Debije, Michael G.; Schenning, Albert P. H. J.

    2017-02-01

    With increase in global warming, use of active cooling and heating devices are continuously increasing to maintain interior temperature of built environment, greenhouses and cars. To reduce the consumption of tremendous amount of energy on cooling and heating devices we need an improved control of transparent features (i.e. windows). In this respect, smart window which is capable for reflecting solar infrared energy without interfering with the visible light would be very attractive. Most of the technologies developed so far are to control the visible light. These technologies block visual contact to the outside world which cause negative effects on human health. An appealing method to selectively control infrared transmission is via utilizing the reflection properties of cholesteric liquid crystals. In our research, we have fabricated a smart window which is capable of reflecting different amount of solar infrared energy depending on the specific climate conditions. The reflection bandwidth can be tuned from 120 nm to 1100 nm in the infrared region without interfering with the visible solar radiations. Calculations reveal that between 8% and 45% of incident solar infrared light can be reflected with a single cell. Simulation studies predicted that more than 12% of the energy spent on heating, cooling and lighting in the built environment can be saved by using the fabricated smart window compared to standard double glazing window.

  13. Ultrasound visualization using polymer dispersed liquid crystal sensors

    Science.gov (United States)

    Edwards, R. S.; Trushkevych, O.; Eriksson, T. J. R.; Ramadas, S. N.; Dixon, S.

    2017-02-01

    The acousto-optic effect in liquid crystals (LCs) has previously been exploited to build large area acoustic sensors for visualising ultrasound fields, opening up the field of acoustography. There is an opportunity to simplify this technique and open new application areas by employing polymer dispersed LC (PDLC) thin films instead of aligned LC layers. In PDLCs, the normally opaque film becomes transparent under the influence of an acoustic field (e.g. when surface acoustic waves are propagating in the material under the film). This is called acoustic clearing and is visible by eye. There is potential for producing ultrasonic sensors which can be `painted on' to a component, giving direct visualisation of the ultrasonic field without requiring scanning. We demonstrate the effect by using PDLC films to characterise a resonant mode of a flexural air-coupled transducer. Visualisation was quick, with a switching time of a few seconds. The effect shows promise for ultrasound sensing applications for transducer characterisation and NDE.

  14. Nematic liquid crystal boojums with handles on colloidal handlebodies.

    Science.gov (United States)

    Liu, Qingkun; Senyuk, Bohdan; Tasinkevych, Mykola; Smalyukh, Ivan I

    2013-06-04

    Topological defects that form on surfaces of ordered media, dubbed boojums, are ubiquitous in superfluids, liquid crystals (LCs), Langmuir monolayers, and Bose-Einstein condensates. They determine supercurrents in superfluids, impinge on electrooptical switching in polymer-dispersed LCs, and mediate chemical response at nematic-isotropic fluid interfaces, but the role of surface topology in the appearance, stability, and core structure of these defects remains poorly understood. Here, we demonstrate robust generation of boojums by controlling surface topology of colloidal particles that impose tangential boundary conditions for the alignment of LC molecules. To do this, we design handlebody-shaped polymer particles with different genus g. When introduced into a nematic LC, these particles distort the nematic molecular alignment field while obeying topological constraints and induce at least 2g - 2 boojums that allow for topological charge conservation. We characterize 3D textures of boojums using polarized nonlinear optical imaging of molecular alignment and explain our findings by invoking symmetry considerations and numerical modeling of experiment-matching director fields, order parameter variations, and nontrivial handle-shaped core structure of defects. Finally, we discuss how this interplay between the topologies of colloidal surfaces and boojums may lead to controlled self-assembly of colloidal particles in nematic and paranematic hosts, which, in turn, may enable reconfigurable topological composites.

  15. Spotlight on Biomimetic Systems Based on Lyotropic Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Juliana F. de Souza

    2017-03-01

    Full Text Available The behavior of lyotropic biomimetic systems in drug delivery was reviewed. These behaviors are influenced by drug properties, the initial water content, type of lyotropic liquid crystals (LLC, swell ability, drug loading rate, the presence of ions with higher or less kosmotropic or chaotropic force, and the electrostatic interaction between the drug and the lipid bilayers. The in vivo interaction between LCC—drugs, and the impact on the bioavailability of drugs, was reviewed. The LLC with a different architecture can be formed by the self-assembly of lipids in aqueous medium, and can be tuned by the structures and physical properties of the emulsion. These LLC lamellar phase, cubic phase, and hexagonal phase, possess fascinating viscoelastic properties, which make them useful as a dispersion technology, and a highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix for drug delivery. In addition, the biodegradable and biocompatible nature of lipids demonstrates a minimum toxicity and thus, they are used for various routes of administration. This review is not intended to provide a comprehensive overview, but focuses on the advantages over non modified conventional materials and LLC biomimetic properties.

  16. Anomalous swimming behavior of bacteria in nematic liquid crystals

    Science.gov (United States)

    Sokolov, Andrey; Zhou, Shuang; Lavrentovich, Oleg; Aranson, Igor

    2015-03-01

    Flagellated bacteria stop swimming in isotropic media of viscosity higher than 0.06kgm-1s-1. However, Bacillus Subtilis slows down by only about 30% in a nematic chromonic liquid crystal (CLC, 14wt% DSCG in water), where the anisotropic viscosity can be as high as 6kgm-1s-1. The bacteria velocity (Vb) is linear with the flagella rotation frequency. The phase velocity of the flagella Vf ~ 2Vb in LC, as compared to Vf ~ 10Vb in water. The flow generated by the bacteria is localized along the bacterial body axis, decaying slowly over tens of micrometers along, but rapidly over a few micrometers across this axis. The concentrated flow grants the bacteria new ability to carry cargo particles in LC, ability not seen in their habitat isotropic media. We attribute these anomalous features to the anisotropy of viscosity of the CLC, namely, the viscosities of splay and twist is hundreds times higher than that of bend deformation, which provides extra boost of swimming efficiency and enables the bacteria swim at considerable speed in a viscous medium. Our findings can potentially lead to applications such as particle transportation in microfluidic devices. A.S and I.A are supported by the US DOE, Office of Science, BES, Materials Science and Engineering Division. S.Z. and O.D.L are supported by NSF DMR 1104850, DMS-1434185.

  17. Key-lock colloids in a nematic liquid crystal

    Science.gov (United States)

    Silvestre, Nuno M.; Tasinkevych, M.

    2017-01-01

    The Landau-de Gennes free energy is used to study theoretically the effective interaction of spherical "key" and anisotropic "lock" colloidal particles. We assume identical anchoring properties of the surfaces of the key and of the lock particles, and we consider planar degenerate and perpendicular anchoring conditions separately. The lock particle is modeled as a spherical particle with a spherical dimple. When such a particle is introduced into a nematic liquid crystal, it orients its dimple at an oblique angle θeq with respect to the far field director n∞. This angle depends on the depth of the dimple. Minimization results show that the free energy of a pair of key and lock particles exhibits a global minimum for the configuration when the key particle is facing the dimple of the lock colloidal particle. The preferred orientation ϕeq of the key-lock composite doublet relative to n∞ is robust against thermal fluctuations. The preferred orientation θeq(2 ) of the dimple particle in the doublet is different from the isolated situation. This is related to the "direct" interaction of defects accompanying the key particle with the edge of the dimple. We propose that this nematic-amplified key-lock interaction can play an important role in self-organization and clustering of mixtures of colloidal particles with dimple colloids present.

  18. Molecular simulation of chevrons in confined smectic liquid crystals

    Science.gov (United States)

    Webster, Richard E.; Mottram, Nigel J.; Cleaver, Douglas J.

    2003-08-01

    Chevron structures adopted by confined smectic liquid crystals are investigated via molecular dynamics simulations of the Gay-Berne model. The chevrons are formed by quenching nematic films confined between aligning planar substrates whose easy axes have opposing azimuthal components. When the substrates are perfectly smooth, the chevron formed migrates rapidly towards one of the confining walls to yield a tilted layer structure. However, when substrate roughness is included, by introducing a small-amplitude modulation to the particle-substrate interaction well depth, a symmetric chevron is formed which remains stable over sufficiently long run times for detailed structural information, such as the relevant order parameters and director orientation, to be determined. For both smooth and rough boundaries, the smectic order parameter remains nonzero across the entire chevron, implying that layer identity is maintained across the chevron tip. Also, when the surface-stabilized chevron does eventually revert to a tilted layer structure, it does so via surface slippage, such that layer integrity is maintained throughout the chevron to tilted layer relaxation process.

  19. Writing and representation in liquid crystal physics research

    Science.gov (United States)

    Wickman, Chad; Haas, Christina; Palffy-Muhoray, Peter

    2008-03-01

    Public understanding of science is often shaped by semiotic systems---linguistic, mathematic, graphic, pictorial---deployed in the textual presentation of scientific findings. Nowhere is this more apparent, perhaps, than in recent debates over climate change where non-linguistic communication has played an integral role in shaping policy decisions. This is one example of many, but it speaks to the need for research that examines how working scientists disseminate knowledge to expert and non-expert alike. Based on the study of text production in liquid crystal physics research, I will discuss the way in which physicists utilize multiple semiotic systems in their research and publications. Findings suggest that shared meanings are often created through a variety of semiotic forms---from linguistic script to equations to graphs to diagrams---and that these forms offer specific meaning potentials for communicating knowledge to different audiences. Ultimately, I argue that an improved understanding of scientific literacy practices is key to the effective communication of science to various constituencies.

  20. Large scale structures in liquid crystal/clay colloids

    Science.gov (United States)

    van Duijneveldt, Jeroen S.; Klein, Susanne; Leach, Edward; Pizzey, Claire; Richardson, Robert M.

    2005-04-01

    Suspensions of three different clays in K15, a thermotropic liquid crystal, have been studied by optical microscopy and small angle x-ray scattering. The three clays were claytone AF, a surface treated natural montmorillonite, laponite RD, a synthetic hectorite, and mined sepiolite. The claytone and laponite were sterically stabilized whereas sepiolite formed a relatively stable suspension in K15 without any surface treatment. Micrographs of the different suspensions revealed that all three suspensions contained large scale structures. The nature of these aggregates was investigated using small angle x-ray scattering. For the clays with sheet-like particles, claytone and laponite, the flocs contain a mixture of stacked and single platelets. The basal spacing in the stacks was independent of particle concentration in the suspension and the phase of the solvent. The number of platelets in the stack and their percentage in the suspension varied with concentration and the aspect ratio of the platelets. The lath shaped sepiolite did not show any tendency to organize into ordered structures. Here the aggregates are networks of randomly oriented single rods.

  1. Antipolar ordering of topological defects in active liquid crystals

    Science.gov (United States)

    Oza, Anand U.; Dunkel, Jörn

    2016-09-01

    ATP-driven microtubule-kinesin bundles can self-assemble into two-dimensional active liquid crystals (ALCs) that exhibit a rich creation and annihilation dynamics of topological defects, reminiscent of particle-pair production processes in quantum systems. This recent discovery has sparked considerable interest but a quantitative theoretical description is still lacking. We present and validate a minimal continuum theory for this new class of active matter systems by generalizing the classical Landau-de Gennes free-energy to account for the experimentally observed spontaneous buckling of motor-driven extensile microtubule bundles. The resulting model agrees with recently published data and predicts a regime of antipolar order. Our analysis implies that ALCs are governed by the same generic ordering principles that determine the non-equilibrium dynamics of dense bacterial suspensions and elastic bilayer materials. Moreover, the theory manifests an energetic analogy with strongly interacting quantum gases. Generally, our results suggest that complex nonequilibrium pattern-formation phenomena might be predictable from a few fundamental symmetry-breaking and scale-selection principles.

  2. Cosmetic Potential of a Liotropic Liquid Crystal Emulsion Containing Resveratrol

    Directory of Open Access Journals (Sweden)

    Laura Bonato Alves Oliveira

    2017-12-01

    Full Text Available Resveratrol is a natural substance that has been the target of many researchers over the years since it presents a variety of potential applications in the areas of cosmetics and medicine as a treatment for some diseases. Due to its high antioxidant capacity but low bioavailability, we evaluated the antiaging potential of resveratrol as a liotropic liquid crystal emulsion. Initially, we performed in vitro assays to quantify both the organoleptic characteristics and stability of the emulsion. Next, an in vivo trial was performed on the faces of 30 volunteers to determine the cream’s cosmetic potential and to measure porphyrins, skin barrier function, skin pigmentation, expression lines, and porosity. The emulsion maintained its characteristics during the in vitro assays and, in the in vivo trial, it had some effect only on pore size in forehead, without any significant effects on the other parameters. We had 6 dropouts throughout the study, then the final number of volunteers was 24. Most volunteers did not show any changes in skin pigmentation throughout the study. Similarly, there was not any noticeable improvement on any other parameters evaluated. However, volunteers related a high level of satisfaction with the product.

  3. Inorganic nanosheet liquid crystals and their applications (Conference Presentation)

    Science.gov (United States)

    Miyamoto, Nobuyoshi

    2016-09-01

    Liquid crystal (LC) phase of inorganic nanosheets is fascinating system in the field of condensed matter physics and for potential applications in many fields. In this lecture, I present my research on the LC nanosheet colloids derived from clay minerals, layered niobates, layered titnates, and layered perovskites. Structural analyses by small angle X-ray scattering and confocal laser scanning microscopy reveals not only meso-scale lamellar or nematic structures in the LC phase but also fractal-like porous structures. In that structure, the nanosheets show translational and rotational Brownian motions as revealed by fast-scanning confocal microscopy. The structure is tunable by many factors such as nanosheet concentration, nanosheet lateral size, salt concentration, solvent, counter cations, and charge density of the nanosheets. Some optimized systems show variable structural colors which will be useful for color materials and sensor devices. Under ac-electric field, the orientation of the nanosheets and LC domain is easily controllable; the electric field response is applicable for fabrication of electro-optic devices and formation of anisotropic composite materials. Among many future applications, inorganic nanosheet/ polymer composites with precisely controllable hierarchical structure are fascinating. We synthesized a cm-scale mono-domain gel of exfoliated LC clay/polymer composite. The gel is printable with a dye and the colored part shows photo-induced anomalous deformation behavior, which will be applicable as chemical actuators.

  4. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    Energy Technology Data Exchange (ETDEWEB)

    Awwal, A; Bauman, B; Gavel, D; Olivier, S; Jones, S; Hardy, J L; Barnes, T; Werner, J S

    2003-02-05

    Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using adaptive optics techniques, which are capable of dealing with both the standard low-order aberrations and higher-order aberrations, including coma and spherical aberration. High-order aberrations have been shown to degrade visual performance for clinical subjects in initial investigations. An adaptive optics phoropter has been designed and constructed based on a Shack-Hartmann sensor to measure the aberrations of the eye, and a liquid crystal spatial light modulator to compensate for them. This system should produce near diffraction-limited optical image quality at the retina, which will enable investigation of the psychophysical limits of human vision. This paper describes the characterization and operation of the AO phoropter with results from human subject testing.

  5. Exploratory development of foams from liquid crystal polymers

    Science.gov (United States)

    Chung, T. S.

    1985-01-01

    Two types of liquid crystal polymer (LCP) compositions were studied and evaluated as structural foam materials. One is a copolymer of 6-hydroxy-2-naphthoic acid, terephthalic acid, and p-acetoxyacetanilide (designed HNA/TA/AAA), and the other is a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (designated HBA/HNA). Experimental results showed that the extruded HNA/TA/AA foams have better mechanical quality and appearance than HBA/HNA foams. Heat treatment improved foam tensile strength and break elongation, but reduced their modulus. The injection molding results indicated that nitrogen foaming agents with a low-pressure process gave better void distribution in the injection molded LCP foams than those made by the conventional injection-molding machine and chemical blowing agents. However, in comparing LCP foams with other conventional plastic foams, HBA/HNA foams have better mechanical properties than foamed ABS and PS, but are comparable to PBT and inferior to polycarbonate foams, especially in heat-deflection temperature and impact resistance energy. These deficiencies are due to LCP molecules not having been fully oriented during the Union-Carbide low-pressure foaming process.

  6. Switchable Solar Window Devices Based on Polymer Dispersed Liquid Crystals

    Science.gov (United States)

    Murray, Joseph; Ma, Dakang; Munday, Jeremy

    Windows are an interesting target for photovoltaics due to the potential for large area of deployment and because glass is already a ubiquitous component of solar cell devices. Many demonstrations of solar windows in recent years have used photovoltaic devices which are semitransparent in the visible region. Much research has focused on enhancing device absorption in the UV and IR ranges as a means to circumvent the basic tradeoff between efficiency and transparency to visible light. Use of switchable solar window is a less investigated alternative approach; these windows utilize the visible spectrum but can toggle between high transparency and high efficiency as needed. We present a novel switchable solar window device based on Polymer Dispersed Liquid Crystals (PDLC). By applying an electric field to the PDLC layer, the device can be switched from an opaque, light diffusing, efficient photovoltaic cell to a clear, transparent window. In the off state (i.e. scattering state), these devices have the added benefits of increased reflectivity for reduced lighting and cooling costs and haze for privacy. Further, we demonstrate that these windows have the potential for self-powering due to the very low power required to maintain the on, or high transparency, state. Support From: University of Maryland and Maryland Nano-center and its Fablab.

  7. Structural Variation in Polyoxomolybdate Hybrid Crystals Comprising Ionic-Liquid Surfactants

    Directory of Open Access Journals (Sweden)

    Takeru Ito

    2014-03-01

    Full Text Available Polyoxomolybdate inorganic-organic hybrid crystals were synthesized with 1-decyl-3-methylimidazolium and 1-dodecyl-3-methylimidazolium as ionic-liquid surfactants. Both hybrid crystals possessed alternate stacking of surfactant layers and octamolybdate (Mo8 monolayers, while the molecular structures of Mo8 were different depending on the surfactants and solvents employed for crystallization. Each Mo8 anion was connected by two sodium cations to form infinite one-dimensional chain. The surfactant chains in these crystals were arranged in a complicatedly bent manner, which will be induced by the weak C–H···O hydrogen bonds between the Mo8 anions and ionic-liquid surfactants.

  8. Secondary and lyotropic liquid crystal membranes for improved aqueous separations

    Science.gov (United States)

    Nemade, Parag Ramesh

    An effective membrane separation process should have high flux (i.e., volume filtered per unit membrane surface area per unit time) and selectivity (i.e., passage of the desired species and rejection of undesired species). This dissertation examined two approaches, secondary membranes and lyotropic liquid crystal membranes, for improving flux and selectivity in aqueous liquid separations. The first part of my work emphasizes the use of pre-deposited secondary membranes and backflushing for controlling membrane fouling in microfiltration and ultrafiltration of biological mixtures. Use of secondary membranes increased the permeate flux in microfiltration by several fold. Protein transmission is also enhanced due to the presence of the secondary membrane, and the amount of protein recovered is more than twice that obtained during filtration of protein-only solutions under otherwise identical conditions. In ultrafiltration, the flux enhancement due to secondary membranes is 50%, or less. For the second part of my research, I developed and evaluated polymerized lyotropic liquid crystal (LLC) thin-film composite membranes. LLC assemblies provide an opportunity to make nanoporous polymer membranes with precise control over chemical and structural features on the nanometer scale, which is currently lacking in commercial reverse osmosis (RO) and nanofiltration (NF) membranes available today. These LLC composite membranes are prepared by photopolymerization of solution-cast films of LLC monomer on an ultrafiltration support membrane. These LLC membranes appeared to exhibit almost linearly increasing ionic rejection based on ionic diameter. LLC monomer was modified to achieve a 15% reduction in channel diameter, through the use of a larger multivalent Eu3+ cation as the carboxylate counterion. However, the monomers synthesized required use of solvents such as tetrahydrofuran, which resulted in the dissolution and damage of the support membranes used. Therefore, this direction

  9. Tunable Fabry-Pérot filter based on one-dimensional photonic crystals with liquid crystal components

    Science.gov (United States)

    Cos, J.; Ferre-Borrull, J.; Pallares, J.; Marsal, L. F.

    2009-03-01

    A theoretical study of a tunable Fabry-Pérot multilayer structure composed of alternating layers of silicon and liquid crystal is presented and analyzed. The structure possesses two resonant frequencies within the stop band with tunable wavelengths and transmission properties. Tuning is achieved by allowing different orientations of the liquid crystal optical axes within the cavity and within the mirrors, while keeping the optical axes parallel to the layers. Applying the transfer matrix method for thin layers of anisotropic materials we demonstrate that the resonant wavelengths depend on the difference between the liquid crystal optical axis orientations. Besides, we are able to obtain a complete characterization of the structure in the form of its Jones matrix. From this, we propose an optical two-channel equalizer for applications around 1.55 μm that allows tuning the two resonant wavelengths and their relative amplitude levels.

  10. Liquefaction of Biopolymers: Solvent-free Liquids and Liquid Crystals from Nucleic Acids and Proteins.

    Science.gov (United States)

    Liu, Kai; Ma, Chao; Göstl, Robert; Zhang, Lei; Herrmann, Andreas

    2017-05-16

    Biomacromolecules, such as nucleic acids, proteins, and virus particles, are persistent molecular entities with dimensions that exceed the range of their intermolecular forces hence undergoing degradation by thermally induced bond-scission upon heating. Consequently, for this type of molecule, the absence of a liquid phase can be regarded as a general phenomenon. However, certain advantageous properties usually associated with the liquid state of matter, such as processability, flowability, or molecular mobility, are highly sought-after features for biomacromolecules in a solvent-free environment. Here, we provide an overview over the design principles and synthetic pathways to obtain solvent-free liquids of biomacromolecular architectures approaching the topic from our own perspective of research. We will highlight the milestones in synthesis, including a recently developed general surfactant complexation method applicable to a large variety of biomacromolecules as well as other synthetic principles granting access to electrostatically complexed proteins and DNA. These synthetic pathways retain the function and structure of the biomacromolecules even under extreme, nonphysiological conditions at high temperatures in water-free melts challenging the existing paradigm on the role of hydration in structural biology. Under these conditions, the resulting complexes reveal their true potential for previously unthinkable applications. Moreover, these protocols open a pathway toward the assembly of anisotropic architectures, enabling the formation of solvent-free biomacromolecular thermotropic liquid crystals. These ordered biomaterials exhibit vastly different mechanical properties when compared to the individual building blocks. Beyond the preparative aspects, we will shine light on the unique potential applications and technologies resulting from solvent-free biomacromolecular fluids: From charge transport in dehydrated liquids to DNA electrochromism to biocatalysis in

  11. Experimental investigations and phase-field simulations of triple-phase-separation kinetics within liquid ternary Co-Cu-Pb immiscible alloys.

    Science.gov (United States)

    Wu, Y H; Wang, W L; Yan, N; Wei, B

    2017-05-01

    The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary Co_{43}Cu_{40}Pb_{17} immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center. Theoretical analyses show that a larger temperature gradient inside a smaller alloy droplet induces the accelerated growth of the surface segregation shell during triple-phase separation. The residual Stokes motion and the asymmetric Marangoni convection result in the appearance of an eccentric Co-rich core and the core deviation degree is closely related to the droplet size and initial velocity. A three-dimensional phase-field model of ternary immiscible alloys, which considers the successive phase separations under the combined effects of Marangoni convection and surface segregation, is proposed to explore the formation mechanisms of three-phase core-shell structures. The simulated core-shell morphologies are consistent with the experimental observations, which verifies the model's validity in reproducing the core-shell dynamic evolution. Numerical results reveal that the development of three-phase three-layer core-shell structures can be attributed to the primary and then secondary phase separations dominated simultaneously by Marangoni convection and surface segregation. Furthermore, the effects of droplet temperature gradient on the growth kinetics of the surface segregation shell are analyzed in the light of phase-field theory.

  12. Experimental investigations and phase-field simulations of triple-phase-separation kinetics within liquid ternary Co-Cu-Pb immiscible alloys

    Science.gov (United States)

    Wu, Y. H.; Wang, W. L.; Yan, N.; Wei, B.

    2017-05-01

    The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary C o43C u40P b17 immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center. Theoretical analyses show that a larger temperature gradient inside a smaller alloy droplet induces the accelerated growth of the surface segregation shell during triple-phase separation. The residual Stokes motion and the asymmetric Marangoni convection result in the appearance of an eccentric Co-rich core and the core deviation degree is closely related to the droplet size and initial velocity. A three-dimensional phase-field model of ternary immiscible alloys, which considers the successive phase separations under the combined effects of Marangoni convection and surface segregation, is proposed to explore the formation mechanisms of three-phase core-shell structures. The simulated core-shell morphologies are consistent with the experimental observations, which verifies the model's validity in reproducing the core-shell dynamic evolution. Numerical results reveal that the development of three-phase three-layer core-shell structures can be attributed to the primary and then secondary phase separations dominated simultaneously by Marangoni convection and surface segregation. Furthermore, the effects of droplet temperature gradient on the growth kinetics of the surface segregation shell are analyzed in the light of phase-field theory.

  13. New Intermetallic Ternary Phosphide Chalcogenide AP2-xXx (A = Zr, Hf; X = S, Se) Superconductors with PbFCl-Type Crystal Structure

    Science.gov (United States)

    Kitô, Hijiri; Yanagi, Yousuke; Ishida, Shigeyuki; Oka, Kunihiko; Gotoh, Yoshito; Fujihisa, Hiroshi; Yoshida, Yoshiyuki; Iyo, Akira; Eisaki, Hiroshi

    2014-07-01

    We have synthesized a series of intermetallic ternary phosphide chalcogenide superconductors, AP2-xXx (A = Zr, Hf; X = S, Se), using the high-pressure synthesis technique. These materials have a PbFCl-type crystal structure (space group P4/nmm) when x is greater than 0.3. The superconducting transition temperature Tc changes systematically with x, yielding dome-like phase diagrams. The maximum Tc is achieved at approximately x = 0.7, at which point the Tc is 6.3 K for ZrP2-xSex (x = 0.75), 5.5 K for HfP2-xSex (x = 0.7), 5.0 K for ZrP2-xSx (x = 0.675), and 4.6 K for Hfp2-xSx (x = 0.5). They are typical type-II superconductors and the upper and lower critical fields are estimated to be 2.92 T at 0 K and 0.021 T at 2 K for ZrP2-xSex (x = 0.75), respectively.

  14. Thermal Analysis, Mechanical and Rheological Behaviour of Melt Manufactured Polyethylene/Liquid Crystal Polymer Blends

    Directory of Open Access Journals (Sweden)

    Ilze ELKSNITE

    2011-07-01

    Full Text Available Modification of properties of conventional thermoplastics with thermotropic liquid crystal polymers, from one hand, allows decrease their viscosities, substantially facilitating processing conditions, and, from another hand, allows increase their exploitation properties. Orientation of the labile structure of liquid crystal polymer in extrusion or injection moulding causes specific reinforcement (so-called self-reinforcement to occur in the blends containing liquid crystal polymer. Up to now the effect of self-reinforcement is mostly investigated in the blends, containing considerable amount of liquid crystal polymer. In this research the effect of minor amounts of liquid crystalline co-polyester modifier on the properties of polyethylene is investigated. Various compositions of laboratory synthesized hydroxybenzoic acid /polyethylene terephtalate copolymer containing polyethylene composites have been manufactured by thermoplastic blending. It has been observed that 1 modulus of elasticity, yield strength and ultimate strength increase with raising the content of liquid crystalline modifier; 2 void content in the investigated polyethylene/liquid crystal copolymer composites is not greater that 1 %; 3 addition of liquid crystalline co-polyester modifier improves arrangement of PE crystalline phase.http://dx.doi.org/10.5755/j01.ms.17.2.483

  15. Spectroscopic and morphological investigation of conjugated photopolymerisable quinquethiophene liquid crystals

    KAUST Repository

    McGlashon, Andrew J.

    2012-09-01

    3′-methyl-(5,5′′-bis[3-ethyl-3-(6-phenyl-hexyloxymethyl) -oxetane])-2,2′:5′,2′′-terthiophene (5T(Me)Ox) is a solution processable small molecule semiconductor displaying smectic-C and nematic liquid crystal phases. The pendant oxetane group can be polymerized in situ in the presence of a suitable photoacid at concentrations ≥1% by weight. Spin-coated films of pure 5T(Me)Ox and 5T(Me)Ox doped with the soluble photoacid were characterized by absorption and photoluminescent spectroscopy. Thick pristine films showed absorption and emission from a crystalline phase. Thin monolayer (<5 nm) films, as well as thicker photoacid doped films, instead showed absorption from an H-aggregate phase and emission from an excimer. Optical microscopy showed a significant change in film structure upon addition of the photoacid; large and well-orientated crystals being replaced by much smaller domains which appear to vary in thickness. Grazing Incidence Wide Angle X-Ray Scattering (GIWAXS) was used to characterize the packing and orientation of molecules in the crystalline and doped samples. The results are consistent with the photoacid doped samples forming layers of H-aggregate phase monolayer sheets parallel to the substrate where the photoacid inhibits the transition into the three-dimensionally ordered crystalline phase. Field-effect transistors and light emitting diodes were constructed incorporating 5T(Me)Ox as the active layer. Pure 5T(Me)Ox field-effect transistors showed good, p-type device characteristics, but the morphological changes upon doping result in a loss of transistor action. In the diodes, curing through melting and exposure to UV light followed by photoacid removal resulted in an increase in current density but a decrease in light emission. These results indicate that the presence of the photoacid (≥1% by weight) can have a dramatic effect on the structure, morphology and device performance of ordered, photopatternable materials for organic

  16. Generation of Perfect Optical Vortices by Using a Transmission Liquid Crystal Spatial Light Modulator

    National Research Council Canada - National Science Library

    Nelson Anaya Carvajal; Cristian H. Acevedo; Yezid Torres Moreno

    2017-01-01

    ... liquid crystal spatial light modulator. We showed theoretically that the size of the annular vortex in the Fourier plane is independent of the spiral phase topological charge but it is dependent on the axicon...

  17. Carbon/Liquid Crystal Polymer Prepreg for Cryogenic and High-Temp Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — KaZaK Composites proposes to develop a pultrusion process to produce carbon fiber / liquid crystal polymer (LCP) prepreg, a first for this category of materials and...

  18. Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

    Science.gov (United States)

    Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

    2016-05-01

    Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

  19. Liquid Crystal on Silicon Non-Mechanical Steering of a Laser Vibrometer System

    National Research Council Canada - National Science Library

    Kuciapinski, Kevin S

    2005-01-01

    .... The coherent laser radar system used was a Laser Vibrometer System. The beam of the laser vibrometer was steered from 0 mrad to 3 mrad at 1 mrad increments using the liquid crystal on silicon (LCOS) device...

  20. Color image recognition by use of a joint transform correlator of three liquid-crystal televisions.

    Science.gov (United States)

    Hsieh, Mei-Li; Hsu, Ken Y; Zhai, Hongchen

    2002-03-10

    We present a joint transform correlator for color image recognition by using three liquid-crystal spatial light modulators. A method for simultaneously obtaining the correlation peaks of red, green, and blue is proposed and experimentally demonstrated.

  1. Electric field generation of Skyrmion-like structures in a nematic liquid crystal.

    Science.gov (United States)

    Cattaneo, Laura; Kos, Žiga; Savoini, Matteo; Kouwer, Paul; Rowan, Alan; Ravnik, Miha; Muševič, Igor; Rasing, Theo

    2016-01-21

    Skyrmions are particle-like topological objects that are increasingly drawing attention in condensed matter physics, where they are connected to inversion symmetry breaking and chirality. Here we report the generation of stable Skyrmion-like structures in a thin nematic liquid crystal film on chemically patterned patchy surfaces. Using the interplay of material elasticity and surface boundary conditions, we use a strong electric field to quench the nematic liquid crystal from a fully aligned phase to vortex-like nematic liquid crystal structures, centered on patterned patches, which carry two different sorts of topological defects. Numerical calculations reveal that these are Skyrmion-like structures, seeded from the surface boojum topological defects and swirling towards the second confining surface. These observations, supported by numerical methods, demonstrate the possibility to generate, manipulate and study Skyrmion-like objects in nematic liquid crystals on patterned surfaces.

  2. Photoinduced Micropattern Alignment of Semiconductor Nanorods with Polarized Emission in a Liquid Crystal Polymer Matrix.

    Science.gov (United States)

    Schneider, Julian; Zhang, Wanlong; Srivastava, Abhishek K; Chigrinov, Vladimir G; Kwok, Hoi-Sing; Rogach, Andrey L

    2017-05-10

    Photoalignment technology provides high alignment quality with an exceptional control over the local director of liquid crystals. Because of the reorientation ability of sulfonic azo dye molecules, they offer high azimuthal and polar anchoring energy with a low pretilt angle for the orientation of liquid crystals and liquid crystal composites. In this work, we make use of this approach to align thin film composites of light-emitting semiconductor nanorods dispersed in a liquid crystal polymer into both one-dimensional and two-dimensional microscale patterns. After unidirectional alignment, the patterns are fabricated by a second irradiation with different polarization azimuth and the employment of a photomask. Fluorescence micrographs reveal the nanorod pattern alignment in domain sizes down to 2 μm. Apart from demonstrating the possibility of controlling the orientation of anisotropic nanocrystals with strongly polarized emission on microscopic scale, our results are promising for the fabrication of complex nanostructures for photonic applications.

  3. Enhanced amplified spontaneous emission in a quantum dot-doped polymer-dispersed liquid crystal

    Science.gov (United States)

    Cao, Mingxuan; Zhang, Yating; Song, Xiaoxian; Che, Yongli; Zhang, Haiting; Yan, Chao; Dai, Haitao; Liu, Guang; Zhang, Guizhong; Yao, Jianquan

    2016-07-01

    Quantum dot-doped polymer-dispersed liquid crystals (QD-PDLCs) were prepared by photoinitiated polymerization and sealed in capillary tubes. The concentration of QDs in the PDLC was 1 wt%. Amplified spontaneous emission (ASE) of the quantum dot-doped polymer-dispersed liquid crystals was observed with 532 nm wavelength laser excitation. The threshold for ASE was 6 mJ cm-2, which is much lower than that for homogeneous quantum dot-doped polymer (25 mJ cm-2). The threshold for ASE was dramatically enhanced when the working temperature exceeded the clearing point of the liquid crystal; this result demonstrates that multi-scattering caused by the liquid crystals effectively improved the path length or dwell time of light in the gain region, which played a key role in decreasing the threshold for ASE.

  4. Small-angle light scattering by monolayer of liquid crystal droplets in polymer matrix

    Directory of Open Access Journals (Sweden)

    A. V. Konkolovich

    2011-09-01

    Full Text Available A method for modeling the angular distribution of light scattered by a monolayer of liquid crystal droplets dispersed in polymer matrix is developed. It is based on the anomalous diffraction and interference approximations.

  5. Polymers and Liquid Crystals Symposium held in Boston, Massachusetts on August 19-23, 2007 (Abstracts)

    National Research Council Canada - National Science Library

    Gin, Douglas L

    2007-01-01

    This grant was used to provide partial travel assistance for 5 invited speakers for a POLY Division symposium titled "Polymers and Liquid Crystals" at the Fall 2007 ACS National Meeting in Boston, MA (Aug. 19-23, 2007...

  6. Photonic manipulation of topological defects in liquid-crystal emulsions doped with azobenzene derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Takahiro [Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Ibaraki (Japan) and Liquid-Crystal Nano-System Project, ERATO/SORST, Japan Science and Technology, Agency, 5-9-9 Tokodai, Tsukuba 300-2635, Ibaraki (Japan)]. E-mail: takahiro.yamamoto@aist.go.jp; Tabe, Yuka [Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Ibaraki (Japan); Liquid-Crystal Nano-System Project, ERATO/SORST, Japan Science and Technology, Agency, 5-9-9 Tokodai, Tsukuba 300-2635, Ibaraki (Japan); Department of Applied Physics, School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjyuku, 169-8555, Tokyo (Japan); Yokoyama, Hiroshi [Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Ibaraki (Japan); Liquid-Crystal Nano-System Project, ERATO/SORST, Japan Science and Technology, Agency, 5-9-9 Tokodai, Tsukuba 300-2635, Ibaraki (Japan)

    2006-06-19

    By modulating liquid-crystal alignment on a colloidal sphere, we successfully manipulated topological defects in glycerol-droplet/liquid-crystal emulsions doped with amphiphilic azobenzene derivatives. At an initial state, a disclination loop (Saturn ring) could be observed around the droplet, in which the azobenzene molecules should adsorb onto the droplet and liquid crystal molecules align normally to the surface of the droplet. On irradiation with ultra-violet light ({lambda} = 365 nm), the disclination loop was unfastened and transformed into two point defects called boojums. This should be attributed to the alignment change of the liquid crystal molecules from normal to planar arrangement triggered by trans-to-cis photoisomerization of the adsorbed azo-dyes. On irradiation with visible light causing cis-to-trans photoisomerization ({lambda} = 435 nm), the boojums went back to the Saturn ring reversibly.

  7. On Regularity Criteria for the Two-Dimensional Generalized Liquid Crystal Model

    Directory of Open Access Journals (Sweden)

    Yanan Wang

    2014-01-01

    Full Text Available We establish the regularity criteria for the two-dimensional generalized liquid crystal model. It turns out that the global existence results satisfy our regularity criteria naturally.

  8. Resonant transport of light from planar polymer waveguide into liquid-crystal microcavity.

    Science.gov (United States)

    Jampani, V S R; Humar, M; Muševič, I

    2013-09-09

    We demonstrate the resonant transfer of light from a planar waveguide to a nematic liquid-crystal microdroplet immersed in water. A wide spectrum of light from a supercontinuum laser source is coupled into a high-refractive-index polymer waveguide using a prism-film coupler. The waveguide is in contact with a water dispersion of droplets from the nematic liquid-crystal 5CB. The evanescent field of the light in the waveguide is resonantly coupled to the whispering-gallery mode resonances, sustained by 5 - 20 μm-sized nematic liquid-crystal droplets, which are in close proximity to the waveguide. The resonant transfer of light is tuned by the temperature-induced shifting of the WGM resonances due to the temperature dependence of the refractive index of the nematic liquid crystal. The measurements are compared to the calculations of the coupled-mode theory.

  9. Self-assembled ordered structures in thin films of HAT5 discotic liquid crystal

    Directory of Open Access Journals (Sweden)

    Piero Morales

    2010-05-01

    Full Text Available Thin films of the discotic liquid crystal hexapentyloxytriphenylene (HAT5, prepared from solution via casting or spin-coating, were investigated by atomic force microscopy and polarizing optical microscopy, revealing large-scale ordered structures substantially different from those typically observed in standard samples of the same material. Thin and very long fibrils of planar-aligned liquid crystal were found, possibly formed as a result of an intermediate lyotropic nematic state arising during the solvent evaporation process. Moreover, in sufficiently thin films the crystallization seems to be suppressed, extending the uniform order of the liquid crystal phase down to room temperature. This should be compared to the bulk situation, where the same material crystallizes into a polymorphic structure at 68 °C.

  10. Electrically tunable Yb-doped fiber laser based on a liquid crystal photonic bandgap fiber device.

    Science.gov (United States)

    Olausson, Christina B; Scolari, Lara; Wei, Lei; Noordegraaf, Danny; Weirich, Johannes; Alkeskjold, Thomas T; Hansen, Kim P; Bjarklev, Anders

    2010-04-12

    We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a tunable liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all-spliced laser cavity based on the liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065 nm by applying an electric field to the silicon assembly.

  11. Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....

  12. Thermomechanical modeling of the thermo-order-mechanical coupling behaviors in liquid crystal elastomers

    Science.gov (United States)

    Jin, Lihua; Zeng, Zhi; Huo, Yongzhong

    2010-11-01

    Liquid crystal elastomer is a kind of anisotropic polymeric material, with complicated micro-structures and thermo-order-mechanical coupling behaviors. In this paper, we propose a method to systematically model these coupling behaviors. We derive the constitutive model in full tensor structure according to the Clausius-Duhem inequality. Two of the constitutive equations represent the mechanical equilibrium and the other two represent the phase equilibrium. Choosing the total free energy as the combination of the neo-classical free energy and the Landau-de Gennes nematic free energy, we obtain the Cauchy stress-deformation gradient relation and the order-mechanical coupling equations. We find the analytical homogeneous solutions of the deformation for the typical mechanical loadings, such as uniaxial stretch, and simple shear in any directions. We also compare the compression behavior of prolate liquid crystal elastomers with the stretch behavior of oblate liquid crystal elastomers. As a result, the stress, strain, temperature, order parameter, biaxiality and the direction of the director of liquid crystal elastomers couple with each other. When the prolate liquid crystal elastomer sample is stretched in the direction parallel to its director, the deviatoric stress makes the mesogens more order and increase the transition temperature. When the sample is sheared or stretched in the direction non-parallel to the director, the director of the liquid crystal elastomer will rotate, and the biaxiality will be induced. Because of the order-mechanical coupling, under infinitesimal deformation, liquid crystal elastomer has anisotropic Young's modulus and zero shear modulus in the direction parallel or perpendicular to the director. While for the oblate liquid crystal elastomers, the stretch parallel to the director will cause the rotation of the director and induce the biaxiality.

  13. Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals.

    Science.gov (United States)

    Armas-Pérez, Julio C; Li, Xiao; Martínez-González, José A; Smith, Coleman; Hernández-Ortiz, J P; Nealey, Paul F; de Pablo, Juan J

    2017-10-31

    Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquid-crystal-surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.

  14. The cone phase of liquid crystals: Triangular lattice of double-tilt ...

    Indian Academy of Sciences (India)

    the cut-off α =20 ˚A, double-tilt cylinders of radius R <200 ˚A are energetically favoured over a distortion-free smectic-C provided κG < -3 x10 6 dyne. We are not aware of any measurements of κG in thermotropic liquid crystals. However, some lyotropic liquid crystals have κG values of this sign and magnitude [14]. It is clear ...

  15. A Polarization Maintaining Filter based on a Liquid-Crystal-Photonic-Bandgap-Fiber

    DEFF Research Database (Denmark)

    Scolari, Lara; Olausson, Christina Bjarnal Thulin; Turchinovich, Dmitry

    2008-01-01

    A polarization maintaining filter based on a liquid-crystal-photonic-bandgap-fiber is demonstrated. Its polarization extinction ratio is 14 dB at 1550 nm. Its tunability is 150 nm.......A polarization maintaining filter based on a liquid-crystal-photonic-bandgap-fiber is demonstrated. Its polarization extinction ratio is 14 dB at 1550 nm. Its tunability is 150 nm....

  16. Poincaré-sphere representation of phase-mostly twisted nematic liquid crystal spatial light modulators

    OpenAIRE

    Durán Bosch, Vicente Andrés; Clemente Pesudo, Pedro Javier; Martínez León, Lluís; Climent Jordà, Vicent; Lancis Sáez, Jesús

    2009-01-01

    We establish necessary conditions in order to design a phase-only wave front modulation system from a liquid crystal display. These conditions determine the dependence of the polarization state of the light emerging from the display on the addressing gray level. The analysis, which is carried out by means of the coherence-matrix formalism, includes the depolarization properties of the device. Two different types of polarization distributions at the output of the liquid crystal cel...

  17. Optomechanical Properties of Stretched Polymer Dispersed Liquid Crystal Films for Scattering Polarizer Applications

    OpenAIRE

    Amimori, Ichiro; Priezjev, Nikolai V.; Pelcovits, Robert A.; Crawford, Gregory P.

    2002-01-01

    A scattering polarizer is created by subjecting a polymer dispersed liquid crystal (PDLC) film to tensile strain. The optomechanical properties of the film are investigated by simultaneously measuring the stress-strain and polarization dependent optical transmission characteristics. The correlation between transmittances of two orthogonal polarizations and the stress-strain curve reveals that the polymer orientation as well as the droplet shape anisotropy influences the liquid crystal alignme...

  18. Impedance of Polymer-Dispersed Liquid Crystals with Carbon Nanofibers in Weak Electric Fields

    Science.gov (United States)

    Zhdanov, K. R.; Romanenko, A. I.; Zharkova, G. M.; Podyacheva, O. Yu.

    2016-11-01

    Impedance of polymer-dispersed liquid crystals modified by carbon nanofibers is studied in fields lower than the threshold field of the director reorientation of a liquid crystal. It is shown that the real and imaginary parts of the impedance obey to the relationship (Zre - X0)2 + (Zim - Y0)2 = R 0 2 , where X0, Y0, and R0 are the fitting parameters depending on the frequency of the exciting electric field.

  19. Do shape invariant solitons in highly nonlocal nematic liquid crystals really exist?

    CERN Document Server

    Petrovic, Milan S; Aleksic, Najdan B; Belic, Milivoj R

    2011-01-01

    We question physical existence of shape invariant solitons in three dimensional nematic liquid crystals. Using modified Petviashvili's method for finding eigenvalues and eigenfunctions, we determine shape invariant solitons in a realistic physical model that includes the highly nonlocal nature of the liquid crystal system. We check the stability of such solutions by propagating them for long distances. We establish that any noise added to the medium or to the fundamental solitons induces them to breathe, rendering them practically unobservable.

  20. Ternary system Tm-Cu-Ge: isothermal section of the phase diagram at 870 K and crystal structures of the compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fedyna, L.O.; Bodak, O.I.; Tokaychuk, Ya.O.; Fedyna, M.F.; Mokra, I.R

    2004-03-24

    The isothermal section of the Tm-Cu-Ge phase diagram at 870 K was constructed using X-ray phase analysis. The existence of three ternary compounds was confirmed: TmCu{sub 2}Ge{sub 2} (structure type CeAl{sub 2}Ga{sub 2}, space group I4/mmm, Pearson code tI10, a=3.99155(8) A, c=10.3285(2) A), Tm{sub 2}CuGe{sub 6} (structure type Ce{sub 2}CuGe{sub 6}, space group Amm2, Pearson code oS18, a=4.061(1) A, b=3.957(4) A, c=20.76(2) A) and Tm{sub 6}Cu{sub 8}Ge{sub 8} (structure type Gd{sub 6}Cu{sub 8}Ge{sub 8}, space group Immm, Pearson code oI22, a=13.7407(3) A, b=6.5995(1) A, c=4.1368(1) A). A new ternary copper germanide TmCu{sub 1.24}Ge{sub 0.76} (structure type CaIn{sub 2}, space group P6{sub 3}/mmc, Pearson code hP6, a=4.42254(8) A, c=7.0477(2) A) was found. The crystal structures of TmCu{sub 2}Ge{sub 2}, Tm{sub 6}Cu{sub 8}Ge{sub 8} and TmCu{sub 1.24}Ge{sub 0.76} were refined by full-profile Rietveld method using X-ray powder diffraction data. The binary compound Tm{sub 0.9}Ge{sub 2} (structure type ZrSi{sub 2}) dissolves up to 5 at.% of Cu. The lattice parameters refined for the sample Tm{sub 31}Cu{sub 5}Ge{sub 64} (a=4.042(1) A, b=15.793(4) A, c=3.906(2) A) slightly increased, compared with Tm{sub 0.9}Ge{sub 2}. The solubility of the third component in the other binary phases was found to be negligible.

  1. X-ray reflectivity reveals ionic structure at liquid crystal-aqueous interfaces.

    Science.gov (United States)

    Hallett, James E; Hayward, Dominic W; Arnold, Thomas; Bartlett, Paul; Richardson, Robert M

    2017-08-23

    Here X-ray reflectivity has been used to determine the structure of liquid crystal monolayers for different cyanobiphenyl homologues supported on aqueous solutions of two different salt species. Sodium iodide induces homeotropic ordering for all of the monolayer forming liquid crystal homologues studied here, and forms a Stern layer of iodide ions at the liquid crystal cyano headgroup, similar to the case of lipids or surfactants supported on electrolyte solutions. The liquid crystal headgroups were also found to penetrate into the water surface when binding with iodide ions. Sodium bromide, however, does not form the same localisation of ions close to a liquid crystal monolayer, and instead appears to produce no noticeable change in the scattering length density of the liquid crystal monolayer compared to pure water. However, on further compression the X-ray reflectivity dramatically changes, revealing the emergence of the so-called "trilayer" structure for 5CB and 8CB. This transition occurs at a lower areal density for sodium bromide than for pure water, and unlike for the uncompressed film, a layer of bromide ions was found at the trilayer-water interface.

  2. Functional Smart Dispersed Liquid Crystals for Nano- and Biophotonic Applications: Nanoparticles-Assisted Optical Bioimaging

    Directory of Open Access Journals (Sweden)

    N. V. Kamanina

    2016-01-01

    Full Text Available Functional nematic liquid crystal structures doped with nano- and bioobjects have been investigated. The self-assembling features and the photorefractive parameters of the structured liquid crystals have been comparatively studied via microscopy and laser techniques. Fullerene, quantum dots, carbon nanotubes, DNA, and erythrocytes have been considered as the effective nano- and biosensitizers of the LC mesophase. The holographic recording technique based on four-wave mixing of the laser beams has been used to investigate the laser-induced change of the refractive index in the nano- and bioobjects-doped liquid crystal cells. The special accent has been given to novel nanostructured relief with vertically aligned carbon nanotubes at the interface: solid substrate-liquid crystal mesophase. It has been shown that this nanostructured relief influences the orienting ability of the liquid crystal molecules with good advantage. As a result, it provokes the orientation of the DNA. The modified functional liquid crystal materials have been proposed as the perspective systems for both the photonics and biology as well as the medical applications.

  3. Reflectance-based Photonic Crystal Liquid Sensors Made of ALD TiO2

    NARCIS (Netherlands)

    Huang, Y.; Pandraud, G.; Sarro, P.M.

    2011-01-01

    A promising concept for a photonic crystal sensor for liquid sensing applications is introduced. The two dimensional photonic crystals are fabricated using a recently developed Atomic layer deposition ARrays Defined by Etch-back technique (AARDE) to obtain large functional surfaces and dense pillar

  4. Polarization Properties of Elliptical-Hole Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Tartarini, Giovanni; Pansera, Marco; Alkeskjold, Thomas Tanggaard

    2007-01-01

    The characteristics of triangular photonic crystal fibers (PCFs) with elliptical holes filled with a nematic liquid crystal (LC) are investigated theoretically. The analysis that is carried out using the finite-element method, including material dispersion effects, shows that LC anisotropy and hole...

  5. Spectroscopic investigation of the far-infrared properties of liquid crystals

    DEFF Research Database (Denmark)

    Reuter, M.; Vieweg, N.; Fischer, B. M.

    2013-01-01

    Liquid crystals are one of the most promising base materials for switchable devices at THz frequencies. Therefore, a precise understanding of the optical parameters is crucial. Here, we present the refractive indices and absorption coefficients for 5 CB and an isothiocyanate terminated liquid cry...

  6. Crystal structures of a ddATP-, ddTTP-, ddCTP, and ddGTP- trapped ternary complex of Klentaq1: insights into nucleotide incorporation and selectivity.

    Science.gov (United States)

    Li, Y; Waksman, G

    2001-06-01

    The mechanism by which DNA polymerase I enzymes function has been the subject of extensive biochemical and structural studies. We previously determined the structure of a ternary complex of the large fragment of DNA polymerase I from Thermus aquaticus (Klentaq1) bound to a primer/template DNA and a dideoxycytidine 5'-triphosphate (ddCTP). In this report, we present the details of the 2.3-A resolution crystal structures of three additional ternary complexes of Klentaq1 bound to a primer/template DNA and a dideoxyguanosine 5'-triphosphate (ddGTP), a dideoxythymidine 5'-triphosphate (ddTTP), or a dideoxyadenosine 5'-triphosphate (ddATP). Comparison of the active site of the four ternary complexes reveals that the protein residues around the nascent base pair (that formed between the incoming dideoxynucleoside triphosphate [ddNTP] and the template base) form a snug binding pocket into which only a correct Watson-Crick base pair can fit. Except in the ternary complex bound to dideoxyguanosine 5'-triphosphate, there are no sequence specific contacts between the protein side chains and the nascent base pair, suggesting that steric constraints imposed by the protein onto the nascent base pair is the major contributor to nucleotide selectivity at the polymerase active site. The protein around the polymerase active site also shows plasticity, which may be responsible for the substrate diversity of the enzyme. Two conserved side chains, Q754 and R573, form hydrogen bonds with the N3 atom in the purine base and O2 atom in the pyrimidine base at the minor groove side of the base pair formed by the incorporated ddNMP and the corresponding template base in all the four ternary complexes. These hydrogen-bonding interactions may provide a means of detecting misincorporation at this position.

  7. Synthesis, crystal structure and properties of two ternary rare earth complexes with aromatic acid and 1,10-phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Na; Wang Shuping; Ma Ruixia; Gao Zhihua [Department of Chemistry, Hebei Normal University, Shijiazhuang 050016 (China); Wang Ruifen [Department of Chemistry, Hebei Normal University, Shijiazhuang 050016 (China)], E-mail: wruifen@mail.hebtu.edu.cn; Zhang Jianjun [Experimental Center, Hebei Normal University, Shijiazhuang 050016 (China)

    2008-09-08

    Two dimeric rare-earth complexes [Eu(o-MOBA){sub 3}phen]{sub 2}.2H{sub 2}O (1), [Tb(o-MOBA){sub 3}phen]{sub 2}.2H{sub 2}O (2), (where o-MOBA = o-methoxybenzoate, phen 1,10-phenanthroline) were synthesized and structurally characterized. Both of them consist of neutral dimeric molecules, crystallize in triclinic system, space group P1-bar. Each RE(III) ion is nine-coordinated with one 1,10-phenanthroline molecule, one bidentate chelating carboxylate group, two bidentate bridging carboxylate groups and two tridentate bridging carboxylate groups. Complex 1 shows bright red luminescence, 2 shows green luminescence under UV light at room temperature, respectively. The thermal analysis indicates that they are all quite stable to heat.

  8. Measurement of group velocity dispersion in a solid-core photonic crystal fiber filled with a nematic liquid crystal.

    Science.gov (United States)

    Wahle, Markus; Kitzerow, Heinz

    2014-08-15

    Liquid crystal-filled photonic crystal fibers (PCFs) are promising candidates for electrically tunable integrated photonic devices. In this Letter, we present group velocity measurements on such fibers. A large mode area PCF, LMA8, was infiltrated with the liquid crystal mixture, E7. The measurements were performed with an interferometric setup. The fiber exhibits several spectral transmission windows in the visible wavelength regime that originate from the bandgap guiding mechanism. The dispersion of these windows is very unusual compared to typical fibers. Our measurements show that it can change from -2500 ps km(-1) nm(-1) to +2500 ps km(-1) nm(-1) within a spectral range of only 15 nm. This leads to multiple zero dispersion wavelengths in the visible wavelength range.

  9. Speckle noise suppression using a helix-free ferroelectric liquid crystal cell

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A L; Andreeva, T B; Kompanets, I N [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Zalyapin, N V [National Research Nuclear University ' ' MEPhI' ' (Russian Federation)

    2014-12-31

    We have studied the method for suppressing speckle noise in patterns produced by a laser based on a fast-response electro-optical cell with a ferroelectric liquid crystal (FLC) in which helicoid is absent, i.e., compensated for. The character of smectic layer deformation in an electric field is considered along with the mechanism of spatially inhomogeneous phase modulation of a laser beam passing through the cell which is accompanied by the destruction of phase relations in the beam. Advantages of a helix-free FLC cell are pointed out as compared to helical crystal cells studied previously. (liquid crystal devices)

  10. Organic alloy systems suitable for the investigation of regular binary and ternary eutectic growth

    Science.gov (United States)

    Sturz, L.; Witusiewicz, V. T.; Hecht, U.; Rex, S.

    2004-09-01

    Transparent organic alloys showing a plastic crystal phase were investigated experimentally using differential scanning calorimetry and directional solidification with respect to find a suitable model system for regular ternary eutectic growth. The temperature, enthalpy and entropy of phase transitions have been determined for a number of pure substances. A distinction of substances with and without plastic crystal phases was made from their entropy of melting. Binary phase diagrams were determined for selected plastic crystal alloys with the aim to identify eutectic reactions. Examples for lamellar and rod-like eutectic solidification microstructures in binary systems are given. The system (D)Camphor-Neopentylglycol-Succinonitrile is identified as a system that exhibits, among others, univariant and a nonvariant eutectic reaction. The ternary eutectic alloy close to the nonvariant eutectic composition solidifies with a partially faceted solid-liquid interface. However, by adding a small amount of Amino-Methyl-Propanediol (AMPD), the temperature of the nonvariant eutectic reaction and of the solid state transformation from plastic to crystalline state are shifted such, that regular eutectic growth with three distinct nonfaceted phases is observed in univariant eutectic reaction for the first time. The ternary phase diagram and examples for eutectic microstructures in the ternary and the quaternary eutectic alloy are given.

  11. Computerized Liquid Crystal Phase Identification by Neural Networks Analysis of Polarizing Microscopy Textures

    Science.gov (United States)

    Karaszi, Zoltan; Konya, Andrew; Dragan, Feodor; Jakli, Antal; CPIP/LCI; CS Dept. of Kent State University Collaboration

    Polarizing optical microscopy (POM) is traditionally the best-established method of studying liquid crystals, and using POM started already with Otto Lehman in 1890. An expert, who is familiar with the science of optics of anisotropic materials and typical textures of liquid crystals, can identify phases with relatively large confidence. However, for unambiguous identification usually other expensive and time-consuming experiments are needed. Replacement of the subjective and qualitative human eye-based liquid crystal texture analysis with quantitative computerized image analysis technique started only recently and were used to enhance the detection of smooth phase transitions, determine order parameter and birefringence of specific liquid crystal phases. We investigate if the computer can recognize and name the phase where the texture was taken. To judge the potential of reliable image recognition based on this procedure, we used 871 images of liquid crystal textures belonging to five main categories: Nematic, Smectic A, Smectic C, Cholesteric and Crystal, and used a Neural Network Clustering Technique included in the data mining software package in Java ``WEKA''. A neural network trained on a set of 827 LC textures classified the remaining 44 textures with 80% accuracy.

  12. Modulations and Fluctuations in Lyotropic Smectic Liquid Crystals.

    Science.gov (United States)

    Wack, Daniel Christopher

    This dissertation is concerned with modulation and fluctuation phenomena in lyotropic smectic liquid crystals. The first Chapter provides a critical summary of the results and suggestions for further experimental investigation. In Chapter 2, the results of a high resolution, synchrotron x-ray powder diffraction study of lattice constants in the P_{beta^' } ("rippled") phase of lecithin-water multilamellar mixtures are given. The variation with water volume fraction phi_{omega} and hydrocarbon chain length N_{c} of the modulation wavevector suggests that membrane curvature and hydration interactions between membranes play a significant role in the modulation. The results are consistent with a Lifshitz phenomenological model for lamellar phases of interacting membranes proposed by Goldstein and Leibler. The phase behavior predicted by the model includes a multicritical point called the Lifshitz Point where the wavelength of the modulation diverges. The experimental results indicate that this multicritical point lies in the vicinity of N_{c} = 9 and phi_{omega} = 0.18. In Chapter 3, a high-resolution synchrotron x-ray study of oriented, supported, hydrated dilaurylphosphatidylcholine in the L_{alpha} (Smectic A or "fluid") phase shows that thermal fluctuations give rise to algebraic decay of positional order in stacking of the bimolecular lamellae, the so-called "Landau-Peierls" state. For planar monocrystalline samples of thickness 10-20 mum, the exponents derived from intensity profiles are in accord with harmonic theory, and indicate a bulk compressional elastic constant B = (1.9 +/- 1.0) x 10 ^8erg/cm^3. Samples of thickness ~ 1-2 mu m show anomalous behavior in the wings of the longitudinal intensity profiles, but are not in accord with harmonic theory, suggesting that surface effects partially quench the thermal fluctuations. In Chapter 4, investigation of the dipalmitoylphosphatidylcholine-cholesterol phase diagram by low and high resolution synchrotron x

  13. Dielectric Response of Polymer Dispersed Liquid Crystal Films.

    Science.gov (United States)

    Seekola, Desmond Laurence

    The dielectric response of three types of PDLC films has been studied as a function of frequency of the applied field and temperature. Each type of film contains nematic liquid crystal E7 in a different polymer binder:epoxy (Epon 828), thermoplastic (PMMA) and UV curable adhesive (Norland 65). A model is developed using an effective medium technique in a self consistent field approximation that reasonably describes the dielectric response of PDLC films as a function of frequency. The electrical properties of the constituent phases are estimated. In the E7/PMMA and E7/Norland 65 films the conductivity of E7 is found to be much greater than PMMA or Norland 65 resulting in charge buildup close of 100 Hz at the droplet/polymer interface. For the E7/Epon film the conductivity of Epon is found to be close to E7 so that there is no charge buildup at the droplet/polymer interface. The effect of charge buildup is more clearly seen in the shielding of the applied field with frequency in the optical transmission measurements. For the PMMA and Norland 65 films the turn on voltage increases as the frequency is decreased below 100 Hz. The optical measurements correlate reasonably well with the dielectric response. The shielding of the droplet field in the PMMA film saturates below a certain frequency. By measuring the shielding as a function of droplet size it is shown that this is due to charge depletion in the droplet. In the Norland film, unlike the PMMA film, the shielding does not completely saturate, tending to increase at very low frequency. These results are compared to the model prediction of the field in the droplet. Using Debye-Huckel theory, the charge carrier concentration and electric field are shown to vary significantly over the volume of the droplet for different values of the applied field. From the temperature dependence of the dielectric response the activation energy associated with side group motion (beta transition) in pure PMMA is calculated. Also the

  14. Visual performance in medical imaging using liquid crystal displays

    Science.gov (United States)

    Tchou, Philip Marcel

    2007-12-01

    This thesis examined the contrast performance of liquid crystal display (LCD) devices for use in medical imaging. Novel experimental methods were used to measure the ability of medical LCD devices to produce just noticeable contrast. It was demonstrated that medical LCD devices are capable of high performance in medical imaging and are suitable for conducting psychovisual research experiments. Novel methods for measuring and controlling the luminance response of an LCD were presented in Chapter 3 and used to develop a software tools to apply DICOM GSDF calibrations. Several medical LCD systems were calibrated, demonstrating that the methods can be used to reliably measure luminance and manipulate fine contrast. Chapter 4 reports on a novel method to generate low contrast bi-level bar patterns by using the full palette of available gray values. The method was used in a two alternative forced choice (2AFC) psychovisual experiment to measure the contrast threshold of human observers. Using a z-score analysis method, the results were found to be consistent with the Barten model of contrast sensitivity. Chapter 5 examined error distortion associated with using z-scores. A maximum likelihood estimation (MLE) method was presented as an alternative and was used to reevaluate the results from Chapter 4. The new results were consistent with the Barten model. Simulations were conducted to evaluate the statistical precision of the MLE method in relation to the number and distribution of trials. In Chapter 6, 2AFC tests were conducted examining contrast thresholds for complex sinusoid, white noise, and filtered noise patterns. The sinusoid test results were consistent with the Barten model while the noise patterns required more contrast for visibility. The effects of adaptation were also demonstrated. A noise visibility index (NVI) was introduced to describe noise power weighted by contrast sensitivity. Just noticeable white and filtered noise patterns exhibited similar NVI

  15. Activation volume of selected liquid crystals in the density scaling regime.

    Science.gov (United States)

    Grzybowski, A; Urban, S; Mroz, S; Paluch, M

    2017-02-09

    In this paper, we demonstrate and thoroughly analyze the activation volumetric properties of selected liquid crystals in the nematic and crystalline E phases in comparison with those reported for glass-forming liquids. In the analysis, we have employed and evaluated two entropic models (based on either total or configurational entropies) to describe the longitudinal relaxation times of the liquid crystals in the density scaling regime. In this study, we have also exploited two equations of state: volumetric and activation volumetric ones. As a result, we have established that the activation volumetric properties of the selected liquid crystals are quite opposite to such typical properties of glass-forming materials, i.e., the activation volume decreases and the isothermal bulk modulus increases when a liquid crystal is isothermally compressed. Using the model based on the configurational entropy, we suggest that the increasing pressure dependences of the activation volume in isothermal conditions and the negative curvature of the pressure dependences of isothermal longitudinal relaxation times can be related to the formation of antiparallel doublets in the examined liquid crystals. A similar pressure effect on relaxation dynamics may be also observed for other material groups in case of systems, the molecules of which form some supramolecular structures.

  16. Determination of sulfonamides in swine muscle after salting-out assisted liquid extraction with acetonitrile coupled with back-extraction by a water/acetonitrile/dichloromethane ternary component system prior to high-performance liquid chromatography.

    Science.gov (United States)

    Tsai, Wen-Hsien; Huang, Tzou-Chi; Chen, Ho-Hsien; Wu, Yuh-Wern; Huang, Joh-Jong; Chuang, Hung-Yi

    2010-01-15

    A salting-out assisted liquid extraction coupled with back-extraction by a water/acetonitrile/dichloromethane ternary component system combined with high-performance liquid chromatography with diode-array detection (HPLC-DAD) was developed for the extraction and determination of sulfonamides in solid tissue samples. After the homogenization of the swine muscle with acetonitrile and salt-promoted partitioning, an aliquot of 1 mL of the acetonitrile extract containing a small amount of dichloromethane (250-400 microL) was alkalinized with diethylamine. The clear organic extract obtained by centrifugation was used as a donor phase and then a small amount of water (40-55 microL) could be used as an acceptor phase to back-extract the analytes in the water/acetonitrile/dichloromethane ternary component system. In the back-extraction procedure, after mixing and centrifuging, the sedimented phase would be water and could be withdrawn easily into a microsyringe and directly injected into the HPLC system. Under the optimal conditions, recoveries were determined for swine muscle fortified at 10 ng/g and quantification was achieved by matrix-matched calibration. The calibration curves of five sulfonamides showed linearity with the coefficient of estimation above 0.998. Relative recoveries for the analytes were all from 96.5 to 109.2% with relative standard deviation of 2.7-4.0%. Preconcentration factors ranged from 16.8 to 30.6 for 1 mL of the acetonitrile extract. Limits of detection ranged from 0.2 to 1.0 ng/g. 2009 Elsevier B.V. All rights reserved.

  17. Facilitated Ion Transport in Smectic Ordered Ionic Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Hong [Materials Architecturing Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5 Seongbuk-gu Seoul 136-791 South Korea; School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University, 599 Gwanak-ro Gwanak-gu Seoul 151-742 South Korea; Han, Kee Sung [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Lee, Je Seung [Department of Chemistry, Kyung Hee University, 26 Kyungheedae-ro Dongdaemun-gu Seoul 02447 South Korea; Lee, Albert S. [Materials Architecturing Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5 Seongbuk-gu Seoul 136-791 South Korea; Park, Seo Kyung [Department of Chemistry, Kyung Hee University, 26 Kyungheedae-ro Dongdaemun-gu Seoul 02447 South Korea; Hong, Sung Yun [Department of Chemistry, Kyung Hee University, 26 Kyungheedae-ro Dongdaemun-gu Seoul 02447 South Korea; Lee, Jong-Chan [School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University, 599 Gwanak-ro Gwanak-gu Seoul 151-742 South Korea; Mueller, Karl T. [Department of Chemistry, Pennsylvania State University, University Park PA 16802 USA; Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Hong, Soon Man [Materials Architecturing Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5 Seongbuk-gu Seoul 136-791 South Korea; Nanomaterials Science and Engineering, University of Science and Technology, Gajeong-ro Yuseong-gu Daejeon 305-350 South Korea; Koo, Chong Min [Materials Architecturing Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5 Seongbuk-gu Seoul 136-791 South Korea; Nanomaterials Science and Engineering, University of Science and Technology, Gajeong-ro Yuseong-gu Daejeon 305-350 South Korea

    2016-09-08

    We investigated a novel ionic mixture of an imidazolium-based room temperature IL containing ethylene oxide functionalized phosphite anion and a lithium salt that self-assembles into a smectic-ordered IL crystal. The two key features in this work are the unique origin of the smectic order of the ionic mixtures and the facilitated ion transport behavior in the smectic ordered IL crystal. In fact, the IL crystals are self-assembled through Coulombic interactions between ion species, not through the hydrophilic-phobic interactions between charged ion heads and hydrophobic long alkyl pendants or the steric interaction between mesogenic moieties. Furthermore, the smectic order in the IL crystal ionogel facilitates exceptional and remarkable ionic transport. Large ionic conductivity, viscoelastic robustness, and additional electrochemical stability of the IL crystal ionogels provide promising opportunities for future electrochemical applications.

  18. Disequilibrium crystal-liquid processes at Hamblin-Cleopatra volcano, Lake Mead area, Nevada

    Science.gov (United States)

    Barker, Daniel S.; Thompson, Keith G.; Smith, Eugene I.; McDowell, Fred W.

    2012-09-01

    The 60 km3 Hamblin-Cleopatra stratovolcano produced shoshonite, latite, and trachyte lavas throughout its Miocene eruptive history. Low-silica rhyolite and silica-undersaturated hawaiite erupted before and after lavas of the Hamblin-Cleopatra volcano. Shoshonite, latite, and trachyte resulted from contamination of felsic (trachyte to low-silica rhyolite) anatectic liquids with crystals from hawaiite. Most of the entrained crystals were not in equilibrium with liquid represented by groundmass, but were mingled with liquid shortly before eruption. Crystal aggregates are common inclusions in the lavas, and are sources of the contaminating minerals. The resulting bulk compositions of these porphyritic lavas form a continuum that resembles a liquid line of descent, as dictated by mass balance.

  19. Direct measurement of the propagation of the phase-transition region of liquid crystals

    Science.gov (United States)

    Sato, Takahiro; Katayama, Kenji

    2017-03-01

    Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions. Despite the technological and fundamental importance of these long-range changes, there is no good physical property with which to express them for the liquid crystal. Here, we show direct measurements of the propagation of structural or orientational changes due to long-range molecular interactions in liquid crystals. We induced a patterned phase transition in a liquid crystal via illumination with a fringe pattern and observed the propagation of the phase-transition region. We determined that the propagation occurred in a ballistic manner with a velocity of 80-110 m/s and that two types of propagation—side-by-side and head-to-tail molecular interactions—were found.

  20. Chitosan as matrix for bio-polymer dispersed liquid crystal systems.

    Science.gov (United States)

    Marin, Luminita; Popescu, Maria-Cristina; Zabulica, Andrei; Uji-I, Hiroshi; Fron, Eduard

    2013-06-05

    The obtaining of bio-polymer dispersed liquid crystal (bio-PDLC) systems based on a chitosan polymer matrix is reported here for the first time. The new PDLC composites have been obtained by encapsulation of 4-cyano-4'-pentylbiphenyl (5CB) as low molecular weight liquid crystal into chitosan, and they have been characterized by polarized optical microscopy, differential scanning calorimetry, electron and transmission scanning microscopy, Raman and fluorescence spectroscopy. Submicrometric liquid crystalline droplets with uniform size distribution and density have been obtained for low liquid crystal content into the PDLCs. The droplets have a radial configuration being anchored into chitosan matrix by an interface ordering coupling phenomenon. Copyright © 2013 Elsevier Ltd. All rights reserved.