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2013

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Articles 1261 - 1290 of 11462

Full-Text Articles in Physical Sciences and Mathematics

As Strong As The Weakest Link: Mining Diverse Cliques In Weighted Graphs, Petko Bogdanov, Ben Baumer, Prithwish Basu, Amotz Bar-Noy, Ambuj K. Singh Oct 2013

As Strong As The Weakest Link: Mining Diverse Cliques In Weighted Graphs, Petko Bogdanov, Ben Baumer, Prithwish Basu, Amotz Bar-Noy, Ambuj K. Singh

Statistical and Data Sciences: Faculty Publications

Mining for cliques in networks provides an essential tool for the discovery of strong associations among entities. Applications vary, from extracting core subgroups in team performance data arising in sports, entertainment, research and business; to the discovery of functional complexes in high-throughput gene interaction data. A challenge in all of these scenarios is the large size of real-world networks and the computational complexity associated with clique enumeration. Furthermore, when mining for multiple cliques within the same network, the results need to be diversified in order to extract meaningful information that is both comprehensive and representative of the whole dataset. We …

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Synthesis Of Environmentally-Friendly Polyurethane Dispersions Based On Soybean Oil- Derived Polyols And Their Applications In Advanced Water-Based And Uv-Cure Coatings, Senthikumar Rengasamy Oct 2013

Synthesis Of Environmentally-Friendly Polyurethane Dispersions Based On Soybean Oil- Derived Polyols And Their Applications In Advanced Water-Based And Uv-Cure Coatings, Senthikumar Rengasamy

Master's Theses and Doctoral Dissertations

Polyurethane dispersions (PUD) have established themselves as most versatile polymeric binder in coating, adhesive, sealant, and elastomer industries. Like any other polymers, PUDs also have certain limitations, such as hydrolytic stability, water resistance, and oil resistance. In order to develop these properties, two different polyol families were synthesized. The first polyol can be used in ambient curable systems, and the second can be utilized in ultraviolet radiation cure coatings. For ambient curable systems polyether chemistry based soy-polyol was developed from epoxidized soy fatty acid methyl ester (ESFAME). The cationic ring opening of oxirane oxygen groups from ESFAME resulted in polyol …

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Simultaneous Redox Conversion Of Chromium(Vi) And Arsenic(Iii) Under Acidic Conditions, Zhaohui Wang, Richard Bush, Leigh Sullivan, Jianshe Liu Oct 2013

Simultaneous Redox Conversion Of Chromium(Vi) And Arsenic(Iii) Under Acidic Conditions, Zhaohui Wang, Richard Bush, Leigh Sullivan, Jianshe Liu

Dr Zhaohui Wang

Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards …

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The Coastlines Of The World With Google Earth: Understanding The Environment, Anja Scheffers, Sander R. Scheffers, Dieter H. Kelletat Oct 2013

The Coastlines Of The World With Google Earth: Understanding The Environment, Anja Scheffers, Sander R. Scheffers, Dieter H. Kelletat

Professor Anja Scheffers

Far away shores, exotic islands or adventurous sea voyages - coasts are the destination of dreams for millions of people around the globe. Large numbers of people also call coasts their home; in many countries a narrow coastal strip is densely populated making these places vulnerable to marine natural hazards such as storms or tsunamis. The book Coastlines of the World with Google Earth aims to draw people's attention (within and outside of the science community) towards coastal sciences and spark interest for the extraordinary diversity and beauty of coastal environments. The book illustrates the fascinating variety of coastal landscapes …

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Structure And Dynamics Of Model Systems: From Ferrofluids To Brain Membranes, Matthew A. Barrett Oct 2013

Structure And Dynamics Of Model Systems: From Ferrofluids To Brain Membranes, Matthew A. Barrett

Matthew J. Barrett

Soft condensed matter systems are a very diverse and challenging subject to study. To understand the complex macro-properties of such systems one approach is to characterize the microscopic structure and dynamics. A powerful technique for determining micro and nanoscale properties is scattering of radiation sources. Light, electron and neutron scattering techniques provide insight into the complicated molecular structures and the processes happening on these small scales. We have used neutron and x-ray scattering techniques to determine structural and dynamical information from two different types of soft condensed matter systems. The microscopic nature of a cobalt magnetic fluid was studied using …

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Capillary Filling Of Nematic Liquid Crystals, Xiang-Dong Mi, Deng-Ke Yang Oct 2013

Capillary Filling Of Nematic Liquid Crystals, Xiang-Dong Mi, Deng-Ke Yang

Deng-Ke Yang

We studied the orientation of nematic liquid crystals when they were being filled into cells by capillary action. We found that, in the flow front, the liquid crystal was always aligned along the flow direction. Far behind the flow front, the orientation of the liquid crystal depended on the anchoring direction of the alignment layers and the direction and speed of the flow. In cells with the anchoring direction parallel to the flow direction, the liquid crystal always oriented along the flow direction. In cells with the anchoring direction perpendicular to the flow direction, at low flow speed gradients, the …

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Ordering And Self-Diffusion In The 1st Molecular Layer At A Liquid-Crystal Polymer Interface, G. P. Crawford, Deng-Ke Yang, S. Zumer, D. Finotello, J. William Doane Oct 2013

Ordering And Self-Diffusion In The 1st Molecular Layer At A Liquid-Crystal Polymer Interface, G. P. Crawford, Deng-Ke Yang, S. Zumer, D. Finotello, J. William Doane

Deng-Ke Yang

H-2 NMR of a liquid crystal confined to submicron cylindrical cavities, in a 17-K interval above the nematic-isotropic transition, reveals a weakly orientationally ordered molecular layer at the cavity wall governed by local interactions. The order (S0 = 0.02) is temperature independent so that a partial wetting is realized with no prewetting transition expected. A molecular exchange rate between the surface layer and the bulk is measured to be approximately 10(3) s-1. The coherence length measuring the order penetrating further into the cavity is described by alpha = 0.4 and xi-0 = 0.6 nm.

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Evolution Of Disclinations In Cholesteric Liquid Crystals, F. Zhang, Deng-Ke Yang Oct 2013

Evolution Of Disclinations In Cholesteric Liquid Crystals, F. Zhang, Deng-Ke Yang

Deng-Ke Yang

We studied the evolution of defect lines (oily streaks) in cholesteric liquid crystals. In contrast to nematic liquid crystals, there were no interactions between the defect lines in cholesteric liquid crystals. We observed experimentally that individual open defect segments shrank with time with a linear relation, and individual defect loops shrank with time with a square root relation. We also observed that the defects in cholesteric liquid crystals were mainly interconnected loops, and the total length of the defect lines decreased with time logarithmically because of the distribution of loop size. The decay constant depended on the helical pitch of …

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Pretransitional Nematic Ordering In Liquid Crystals With Dispersed Polymer Networks, Y. K. Fung, A. Borstnik, S. Zumer, Deng-Ke Yang, J. William Doane Oct 2013

Pretransitional Nematic Ordering In Liquid Crystals With Dispersed Polymer Networks, Y. K. Fung, A. Borstnik, S. Zumer, Deng-Ke Yang, J. William Doane

Deng-Ke Yang

The birefringence induced by partially ordered polymer networks dispersed in an isotropic phase of liquid crystals is studied. Polymer networks were formed by the polymerization of 1-4 % mixtures of prepolymer in the nematic phase of liquid crystals. The partial nematic (paranematic) ordering is analyzed in terms of the Landau-de Gennes approach using a simple model of an array of thin fibrils, which can, on a large scale, form bundles of polymer-rich material. The comparison of the theory and birefringence data clearly shows that the main building bloc of the network is a few nanometers thick fibril. The average thickness …

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Effect Of Chiral Dopant On The Performance Of Polymer Dispersed Liquid Crystal Light Valve, Z. J. Lu, Deng-Ke Yang Oct 2013

Effect Of Chiral Dopant On The Performance Of Polymer Dispersed Liquid Crystal Light Valve, Z. J. Lu, Deng-Ke Yang

Deng-Ke Yang

We have experimentally studied the effect of chiraldopant on the electro‐optical performance of a polymer‐dispersed liquid crystal(PDLC) light valve. Adding a small amount of chiraldopant decreases the turn‐OFF time significantly but increases the drive voltage only slightly. A phenomenological theory is presented to explain the experimental results.

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Light-Scattering From Polymer-Dispersed Liquid-Crystal Films - Droplet Size Effects, G, Paul Montgomery Jr, John L. West, W Tamuralis Oct 2013

Light-Scattering From Polymer-Dispersed Liquid-Crystal Films - Droplet Size Effects, G, Paul Montgomery Jr, John L. West, W Tamuralis

John L West

The effects of droplet size on light scattering by polymer-dispersed liquid crystal (PDLC) films have been studied theoretically and experimentally. Rayleigh-Gans calculations predict that, provided the droplets scatter independently, backscattering will be maximum at wavelength lambda when the droplet radius is about lambda/7. noticeable for droplet volume fractions eta above about 0.2 and shift the radius for maximum backscattering to about lambda/5 as eta increases to 0.5. These calculations are consistent with hemispherical transmittance and reflectance measurements on PDLC films in which multiple scattering is known to be important. These measurements indicate that solar attenuation by PDLC films will probably …

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Drag On Particles In A Nematic Suspension By A Moving Nematic-Isotropic Interface, John L. West, A Glushchenko, Gx Liao, Y Reznikov, D Andrienko, Mp Allen Oct 2013

Drag On Particles In A Nematic Suspension By A Moving Nematic-Isotropic Interface, John L. West, A Glushchenko, Gx Liao, Y Reznikov, D Andrienko, Mp Allen

John L West

We report a clear demonstration of drag on colloidal particles by a moving nematic-isotropic interface. The balance of forces explains our observation of periodic, striplike structures that are produced by the movement of these particles.

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Field-Induced Polymer Wall Formation In A Bistable Smectic-A Liquid Crystal Display, Ebru A. Buyuktanir, Nadina Gheorghiu, John L. West, Maxim Mitrokhin, Borre Holter, Anatoliy Glushchenko Oct 2013

Field-Induced Polymer Wall Formation In A Bistable Smectic-A Liquid Crystal Display, Ebru A. Buyuktanir, Nadina Gheorghiu, John L. West, Maxim Mitrokhin, Borre Holter, Anatoliy Glushchenko

John L West

We developed a composite system to produce robust bistable smectic-A (SmA) liquid crystal based flexible displays by encapsulating the liquid crystal material in a polymer wall structure. While keeping all the intrinsic bistable properties of the SmA material, the field-induced polymer walls bridge the two display substrates and bring significant advantages over the polymer dispersed liquid crystal structure. Here we analyze the performance of an encapsulated pixel and demonstrate superior electro-optical characteristics, high contrast ratio, and excellent sunlight readability. (c) 2006 American Institute of Physics.

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One Order Parameter Tensor Mean Field Theory For Biaxial Liquid Crystals, Xiaoyu Zheng, Peter Palffy-Muhoray Oct 2013

One Order Parameter Tensor Mean Field Theory For Biaxial Liquid Crystals, Xiaoyu Zheng, Peter Palffy-Muhoray

Xiaoyu Zheng

In this paper, we present a simple one tensor mean field model of biaxial nematic liquid crystals. The salient feature of our approach is that material parameters appear explicitly in the order parameter tensor. We construct the free energy from a mean field potential based on anisotropic dispersion interactions, identify the order parameter tensor and its elements, and obtain self-consistent equations, which are then solved numerically. The results are illustrated in a 3D ternary phase diagram. The phase behavior can be simply related to molecular parameters. The results may be useful for designing molecules that show a thermotropic biaxial phase.

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Modeling Elastic Instabilities In Nematic Elastomers, Badel L. Mbanga, Fangfu Ye, Jonathan Selinger, Robin Selinger Oct 2013

Modeling Elastic Instabilities In Nematic Elastomers, Badel L. Mbanga, Fangfu Ye, Jonathan Selinger, Robin Selinger

Robin Selinger

Liquid crystal elastomers are cross-linked polymer networks covalently bonded with liquid crystal mesogens. In the nematic phase, due to strong coupling between mechanical strain and orientational order, these materials display strain-induced instabilities associated with formation and evolution of orientational domains. Using a three-dimensional finite element elastodynamics simulation, we investigate one such instability, the onset of stripe formation in a monodomain film stretched along an axis perpendicular to the nematic director. In our simulation, we observe the formation of striped domains with alternating director rotation. This model allows us to explore the fundamental physics governing dynamic mechanical response of nematic elastomers …

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A Cellulose Liquid Crystal Motor: A Steam Engine Of The Second Kind, Yong Geng, Pedro Lucio Almeida, Cheng Cheng, Peter Palffy-Muhoray, Maria Helena Godinho, Susete Nogueira Fernandes Oct 2013

A Cellulose Liquid Crystal Motor: A Steam Engine Of The Second Kind, Yong Geng, Pedro Lucio Almeida, Cheng Cheng, Peter Palffy-Muhoray, Maria Helena Godinho, Susete Nogueira Fernandes

Peter Palffy-Muhoray

The salient feature of liquid crystal elastomers and networks is strong coupling between orientational order and mechanical strain. Orientational order can be changed by a wide variety of stimuli, including the presence of moisture. Changes in the orientation of constituents give rise to stresses and strains, which result in changes in sample shape. We have utilized this effect to build soft cellulose-based motor driven by humidity. The motor consists of a circular loop of cellulose film, which passes over two wheels. When humid air is present near one of the wheels on one side of the film, with drier air …

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Nonlinear Schrodinger Equation In Nematic Liquid Crystals, Peter Palffy-Muhoray, J. A. Reyes Oct 2013

Nonlinear Schrodinger Equation In Nematic Liquid Crystals, Peter Palffy-Muhoray, J. A. Reyes

Peter Palffy-Muhoray

We derive the amplitude equation, in the weakly nonlinear regime, for an optical wave packet that propagates in an initially undistorted nematic liquid crystal. By using the dyad representation Q(ij), we find the retarded and nonlocal equation for the nematic configuration and solve it in Fourier space. This allows us to calculate the amplitude dependent dispersion relation for a nematic liquid crystal in a given initial undistorted stationary state. We consider a linearly polarized wave packet that travels along the principal axis of the nematic dielectric tensor. We find a nonlinear Schrodinger equation for the amplitude, which includes an additional …

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Pattern Formation In Non-Newtonian Hele-Shaw Flow, P. Fast, L. Kondic, M. J. Shelley, Peter Palffy-Muhoray Oct 2013

Pattern Formation In Non-Newtonian Hele-Shaw Flow, P. Fast, L. Kondic, M. J. Shelley, Peter Palffy-Muhoray

Peter Palffy-Muhoray

We study theoretically the Saffman-Taylor instability of an air bubble expanding into a non-Newtonian fluid in a Hele-Shaw cell, with the motivation of understanding suppression of tip-splitting and the formation of dendritic structures observed in the flow of complex fluids, such as polymeric liquids or liquid crystals. A standard visco-elastic flow model is simplified in the case of flow in a thin gap, and it is found that there is a distinguished limit where shear thinning and normal stress differences are apparent, but elastic response is negligible. This observation allows formulation of a generalized Darcy's law, where the pressure satisfies …

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Nonphotochemical Laser-Induced Nucleation Of Nematic Phase And Alignment Of Nematic Director From A Supercooled Thermotropic Liquid Crystal, Xiaoying Sun, Bruce A. Garetz, Michele F. Moreira, Peter Palffy-Muhoray Oct 2013

Nonphotochemical Laser-Induced Nucleation Of Nematic Phase And Alignment Of Nematic Director From A Supercooled Thermotropic Liquid Crystal, Xiaoying Sun, Bruce A. Garetz, Michele F. Moreira, Peter Palffy-Muhoray

Peter Palffy-Muhoray

A nonphotochemical laser-induced phase transition was studied in a supercooled 4′‐n-pentyl-4-cyanobiphenyl (5CB, also referred to as PCB and K15) liquid crystal, using linearly polarized 45 ps light pulses at a wavelength of 532 nm. The laser induced nucleation from the metastable supercooled isotropic phase to the nematic phase during slow cooling (0.001 °C∕min) and high light intensity (3.9 MW∕cm2). The resulting nematic director tended to be aligned along the direction of the plane of polarization of the light. At the intensities used, there is no observable laser-induced realignment of the director once the sample is in the nematic …

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Cholesteric Liquid-Crystal Laser As An Optic Fiber-Based Temperature Sensor, M. F. Moreira, I.C.S. Carvalho, W. Cao, C. Bailey, Bahman Taheri, Peter Palffy-Muhoray Oct 2013

Cholesteric Liquid-Crystal Laser As An Optic Fiber-Based Temperature Sensor, M. F. Moreira, I.C.S. Carvalho, W. Cao, C. Bailey, Bahman Taheri, Peter Palffy-Muhoray

Peter Palffy-Muhoray

In this work, we have studied the temperature dependence of a cholesteric liquid-crystal laser coupled to an optical fiber, with a view towards optical fiber sensor applications. To stabilize the laser emission, we developed a procedure to align the liquid crystal placed in the fiber. Unexpected oscillations in the laser emission were observed as the temperature was varied, which can be understood in terms of the competition between bulk and surface anchoring torques. (C) 2004 American Institute of Physics.

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Distance Of Closest Approach Of Two Arbitrary Hard Ellipses In Two Dimensions, Xiaoyu Zheng, Peter Palffy-Muhoray Oct 2013

Distance Of Closest Approach Of Two Arbitrary Hard Ellipses In Two Dimensions, Xiaoyu Zheng, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The distance of closest approach of hard particles is a key parameter of their interaction and plays an important role in the resulting phase behavior. For nonspherical particles, the distance of closest approach depends on orientation, and its calculation is surprisingly difficult. Although overlap criteria have been developed for use in computer simulations [ Vieillard-Baron J. Chem. Phys. 56 4729 (1972); Perram and Wertheim J. Comput. Phys. 58 409 (1985)], no analytic solutions have been obtained for the distance of closest approach of ellipsoids in three dimensions, or, until now, for ellipses in two dimensions. We have derived an analytic …

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Identified Baryon And Meson Distributions At Large Transverse Momenta From Au Plus Au Collisions At Root(S)(Nn)=200 Gev, B. I. Abelev, Quan Li, Star Collaboration Oct 2013

Identified Baryon And Meson Distributions At Large Transverse Momenta From Au Plus Au Collisions At Root(S)(Nn)=200 Gev, B. I. Abelev, Quan Li, Star Collaboration

Quan Li

Transverse momentum spectra of pi(+/-), p, and (p) over bar p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at root s(NN) = 200 GeV are presented. In central Au + Au collisions, both pi(+/-) and p((p) over bar) show significant suppression with respect to binary scaling at p(T) greater than or similar to 4 GeV/c. Protons and antiprotons are less suppressed than pi(+/-), in the range 1.5 less than or similar to p(T) less than or similar to 6 GeV/c. The pi(-)/pi(+) and (p) over bar /p ratios show at most a weak pT …

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Coexistence Of Two Colloidal Crystals At The Nematic-Liquid-Crystal-Air Interface, A. B. Nych, V. M. Pergamenshchik, B. I. Lev, V. G. Nazarenko, I. Muševič, M. Škarabot, Oleg Lavrentovich Oct 2013

Coexistence Of Two Colloidal Crystals At The Nematic-Liquid-Crystal-Air Interface, A. B. Nych, V. M. Pergamenshchik, B. I. Lev, V. G. Nazarenko, I. Muševič, M. Škarabot, Oleg Lavrentovich

Oleg Lavrentovich

Glycerol droplets at a nematic-liquid-crystal–air interface form two different lattices—hexagonal and dense quasihexagonal—which are separated by the energy barrier and can coexist. Director distortions around each droplet form an elastic dipole. The first order transition between the two lattices is driven by a reduction of the dipole-dipole repulsion through reorientation of these dipoles. The elastic-capillary attraction is essential for the both lattices. The effect has a many-body origin.

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Pretransitional Fluctuations In The Isotropic Phase Of A Lyotropic Chromonic Liquid Crystal, Yuriy A. Nastishin, Sergij V. Shiyanovskii, Oleg Lavrentovich, A. F. Kostko, M. A. Anisimov Oct 2013

Pretransitional Fluctuations In The Isotropic Phase Of A Lyotropic Chromonic Liquid Crystal, Yuriy A. Nastishin, Sergij V. Shiyanovskii, Oleg Lavrentovich, A. F. Kostko, M. A. Anisimov

Oleg Lavrentovich

We have studied isotropic-to-nematic pretransitional fluctuations in an aqueous solution of disodium cromoglycate (cromolyn) by static and dynamic light scattering. Cromolyn is a representative of lyotropic chromonic liquid crystals with building units being elongated rods formed by aggregates of disk-like molecules. By combining light-scattering and viscosity measurements we have determined the correlation length and relaxation time of the orientational order-parameter fluctuations and estimated the size of the cromolyn aggregates. The pretransitional behavior of light scattering does not completely follow the classic Landau-de Gennes model. This feature is most probably associated with the variable length of cromolyn aggregates. We have observed …

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Undulations In A Confined Lamellar System With Surface Anchoring, T. Ishikawa, Oleg Lavrentovich Oct 2013

Undulations In A Confined Lamellar System With Surface Anchoring, T. Ishikawa, Oleg Lavrentovich

Oleg Lavrentovich

We visualize undulations in layered systems using a cholesteric stripe phase with a macroscopic supramicron periodicity. The wave vector of stripe pattern is in the cell's plane. The-undulation is induced by an in-plane magnetic field normal to the stripes. The observed displacement of layers is much larger than the value predicted by the Helfrich-Hurault classic theory. We propose a model of undulations that explains the data by finite surface anchoring of layers.

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Curvature Energy Of A Focal Conic Domain With Arbitrary Eccentricity, Maurice Kleman, Oleg Lavrentovich Oct 2013

Curvature Energy Of A Focal Conic Domain With Arbitrary Eccentricity, Maurice Kleman, Oleg Lavrentovich

Oleg Lavrentovich

The most frequently observed focal conic domains (FCD’s) in lamellar phases are those based on confocal paris of ellipse and hyperbola. Experimentally, the eccentricity of the ellipse takes a broad range of values 0<~eeisolated FCD reaches a minimum only at e⃗1 (under the constraint of a fixed major semiaxis of the ellipse); exceptions include situations with large saddle-splay elastic constant and small domains where the applicability of the elastic theory is limited. In realistic cases, a value of eccentricity smaller than 1 is stabilized by factors other than the curvature energy: by dislocations emerging from the FCD’s …

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Stripe Domain Phase Of A Thin Nematic Film And The K13 Divergence Term, Oleg Lavrentovich, V. M. Pergamenshchik Oct 2013

Stripe Domain Phase Of A Thin Nematic Film And The K13 Divergence Term, Oleg Lavrentovich, V. M. Pergamenshchik

Oleg Lavrentovich

To verify the status of the divergence K13 term in the elastic theory of liquid crystals we study submicron films placed onto an isotropic fluid substrate in the Langmuir trough (Langmuir liquid crystal, LLC). The upper and lower surfaces favor normal and tangential molecular orientation, respectively. The periodic domain phase is observed in a nematic LLC. The dependence of the periodicity L of the domains vs film thickness h can be explained only if the elastic energy is accompanied by divergence terms with nonzero constants K13 and K24. It is found that for 5CB K13 almost-equal-to -0.2K11.

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Tensor And Complex Anchoring In Liquid Crystals, Sergij V. Shiyanovskii, Anatoliy Glushchenko, Yuri Reznikov, Oleg Lavrentovich, John L. West Oct 2013

Tensor And Complex Anchoring In Liquid Crystals, Sergij V. Shiyanovskii, Anatoliy Glushchenko, Yuri Reznikov, Oleg Lavrentovich, John L. West

Oleg Lavrentovich

We propose a tensor description of surface anchoring of liquid crystals ~LCs!. The model allows one to consider both the homogeneous and inhomogeneous parts of LC anchoring and to calculate the cumulative effect of different treatments as a sum of corresponding tensors. For the planar alignment the tensor representation is reduced to the complex azimuthal anchoring coefficient, whose amplitude and phase determine, respectively, the strength of azimuthal anchoring and the azimuthal angle of the easy axis. We predict and experimentally confirm that two consecutive photoalignment treatments with beams of perpendicular polarizations can compensate each other and restore the initial anchoring.

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Effect Of Director Distortions On Morphologies Of Phase Separation In Liquid Crystals, D. Voloschenko, Oleg P. Pishnyak, Sergij V. Shiyanovskii, Oleg Lavrentovich Oct 2013

Effect Of Director Distortions On Morphologies Of Phase Separation In Liquid Crystals, D. Voloschenko, Oleg P. Pishnyak, Sergij V. Shiyanovskii, Oleg Lavrentovich

Oleg Lavrentovich

We study phase separation from a nematic liquid crystal with spatially nonuniform director gradients. Particles of a phase-separated component, which is either an isotropic fluid (silicone oil) or a nonmesogenic photopolymer, accumulate in the regions with the strongest director distortions, thus reducing the overall energy of the system.

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Anchoring-Mediated Interaction Of Edge Dislocations With Bounding Surfaces In Confined Cholesteric Liquid Crystals, Ivan I. Smalyukh, Oleg Lavrentovich Oct 2013

Anchoring-Mediated Interaction Of Edge Dislocations With Bounding Surfaces In Confined Cholesteric Liquid Crystals, Ivan I. Smalyukh, Oleg Lavrentovich

Oleg Lavrentovich

We employ the fluorescent confocal polarizing microscopy to image edge dislocations in cholesteric liquid crystals. Surface anchoring at the bounding plates determines the structure and behavior of defects. Two types of plates set in-plane director orientation but differ in the type of associated anchoring potentials. Plates with strong polar anchoring and nonzero azimuthal anchoring repel the dislocations, while plates with weak polar anchoring and no azimuthal anchoring allow the dislocations to escape through the boundary. To explain the results, we propose a coarse-grained model of cholesteric anchoring.

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