Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 22 of 22

Full-Text Articles in Physics

The Intermediate Filament Protein, Synemin, Is An Akap In The Heart, Mary Russell, Linda M. Lund, Roy Haber, Kathleen Mckeegan, Nicholas Cianciola, Meredith Bond Dec 2006

The Intermediate Filament Protein, Synemin, Is An Akap In The Heart, Mary Russell, Linda M. Lund, Roy Haber, Kathleen Mckeegan, Nicholas Cianciola, Meredith Bond

Biological Sciences Publications

Targeting of protein kinase A (PKA) by A-kinase anchoring proteins (AKAPs) contributes to high specificity of PKA signaling pathways. PKA phosphorylation of myofilament and cytoskeletal proteins may regulate myofibrillogenesis and myocyte remodeling during heart disease; however, known cardiac AKAPs do not localize to these regions. To identify novel AKAPs which target PKA to the cytoskeleton or myofilaments, a human heart cDNA library was screened and the intermediate filament (IF) protein, synemin, was identified as a putative RII (PKA regulatory subunit type II) binding protein. A predicted RII binding region was mutated and resulted in loss of RII binding. Furthermore, synemin ...


Dynamic Light Scattering Study Of Biaxial Ordering In A Thermotropic Liquid Crystal, K. Neupane, S. W. Kang, D. Carney, T. Meyer, G. H. Mehl, David W. Allender, Satyendra Kumar, S. Sprunt Nov 2006

Dynamic Light Scattering Study Of Biaxial Ordering In A Thermotropic Liquid Crystal, K. Neupane, S. W. Kang, D. Carney, T. Meyer, G. H. Mehl, David W. Allender, Satyendra Kumar, S. Sprunt

Physics Publications

Dynamic light scattering from orientational order fluctuations in a liquid crystalline tetrapode reveals successive, weakly first-order isotropic to uniaxial and uniaxial to biaxial nematic phase transitions. The order parameter relaxation rates exhibit temperature dependences consistent with Landau–de Gennes mean field theory. Combined with previous evidence of a second-order uniaxial-biaxial transition in a closely related tetrapode, the present study supports the existence of a nematic-nematic tricritical point in thermotropic liquid crystals.


Dynamic Light Scattering Study Of Biaxial Ordering In A Thermotropic Liquid Crystal, K. Neupane, Shin-Woong Kang, S. Sharma, D. Carney, T. Meyer, G. H. Mehl, David W. Allender, Satyendra Kumar, S. Sprunt Nov 2006

Dynamic Light Scattering Study Of Biaxial Ordering In A Thermotropic Liquid Crystal, K. Neupane, Shin-Woong Kang, S. Sharma, D. Carney, T. Meyer, G. H. Mehl, David W. Allender, Satyendra Kumar, S. Sprunt

Physics Publications

Dynamic light scattering from orientational order fluctuations in a liquid crystalline tetrapode reveals successive, weakly first-order isotropic to uniaxial and uniaxial to biaxial nematic phase transitions. The order parameter relaxation rates exhibit temperature dependences consistent with Landau–de Gennes mean field theory. Combined with previous evidence of a second-order uniaxial-biaxial transition in a closely related tetrapode, the present study supports the existence of a nematic-nematic tricritical point in thermotropic liquid crystals.


Phase Separation In Bilayer Lipid Membranes: Effects On The Inner Leaf Due To Coupling To The Outer Leaf, David W. Allender, M. Schick Oct 2006

Phase Separation In Bilayer Lipid Membranes: Effects On The Inner Leaf Due To Coupling To The Outer Leaf, David W. Allender, M. Schick

Physics Publications

The combined effects of the tendency of cholesterol to order lipids in the liquid phase and the coupling between lipids in the two leaves of a bilayer are investigated theoretically utilizing a Landau free energy. We show that as a consequence of these combined effects, lateral phase separation in the outer leaf between cholesterol-rich and -poor liquids causes a similar, but weaker, phase separation in the inner leaf. Just as the areal density of lipids in the outer leaf increases in the cholesterol-rich regions, so the areal density of lipids also increases in the inner leaf. Thus, the areal density ...


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 2006

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

Chemical Physics Publications

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 ...


Giant Flexoelectricity Of Bent-Core Nematic Liquid Crystals, John Harden, Badel L. Mbanga, Nandor Éber, Katalin Fodor-Csorba, Samuel N. Sprunt, Jim T. Gleeson, Antal Jakli Oct 2006

Giant Flexoelectricity Of Bent-Core Nematic Liquid Crystals, John Harden, Badel L. Mbanga, Nandor Éber, Katalin Fodor-Csorba, Samuel N. Sprunt, Jim T. Gleeson, Antal Jakli

Chemical Physics Publications

Flexoelectricity is a coupling between orientational deformation and electric polarization. We present a direct method for measuring the flexoelectric coefficients of nematic liquid crystals (NLCs) via the electric current produced by periodic mechanical flexing of the NLC's bounding surfaces. This method is suitable for measuring the response of bent-core liquid crystals, which are expected to demonstrate a much larger flexoelectric effect than traditional, calamitic liquid crystals. Our results reveal that not only is the bend flexoelectric coefficient of bent-core NLCs gigantic (more than 3 orders of magnitude larger than in calamitics) but also it is much larger than would ...


Comment On "Structure Of Smectic Defect Cores: X-Ray Study Of 8cb Liquid Crystal Ultrathin Films", Oleg Lavrentovich, M. Kleman Oct 2006

Comment On "Structure Of Smectic Defect Cores: X-Ray Study Of 8cb Liquid Crystal Ultrathin Films", Oleg Lavrentovich, M. Kleman

Chemical Physics Publications

No abstract provided.


Three-Dimensional Imaging Of Dielectric Patterns In Electrohydrodynamic Convection Of A Nematic Liquid Crystal, N. Gheorghiu, Ivan I. Smalyukh, Oleg Lavrentovich, Jim T. Gleeson Oct 2006

Three-Dimensional Imaging Of Dielectric Patterns In Electrohydrodynamic Convection Of A Nematic Liquid Crystal, N. Gheorghiu, Ivan I. Smalyukh, Oleg Lavrentovich, Jim T. Gleeson

Chemical Physics Publications

The transition from surface to bulk normal dielectric rolls in a nematic liquid crystal is imaged by fluorescence confocal polarizing microscopy. The three-dimensional director structure and the liquid flow are scanned in both the layer plane and the transverse plane. Two systems of small-scale convective flow are formed, one at each electrode. Strong anchoring makes director oscillations difficult and charges accumulate by the Carr-Helfrich mechanism. The middle region is a structureless convection where the director oscillates with the frequency of the applied voltage. The small-scale flow eventually fills the cell from one electrode to the other as one system of ...


Orientational Coupling Amplification In Ferroelectric Nematic Colloids, Fenghua Li, Oleksandr Buchnev, Chae Il Cheon, Anatoliy Glushchenko, Victor Reshetnyak, Yuri Reznikov, Timothy J. Sluckin, John L. West Oct 2006

Orientational Coupling Amplification In Ferroelectric Nematic Colloids, Fenghua Li, Oleksandr Buchnev, Chae Il Cheon, Anatoliy Glushchenko, Victor Reshetnyak, Yuri Reznikov, Timothy J. Sluckin, John L. West

Chemistry & Biochemistry Publications

We investigated the physical properties of low concentration ferroelectric nematic colloids, using calorimetry, optical methods, infrared spectroscopy, and capacitance studies. The resulting homogeneous colloids possess a significantly amplified nematic orientational coupling. We find that the nematic orientation coupling increases by similar to 10% for particle concentrations of 0.2%. A manifestation of the increased orientational order is that the clearing temperature of a nematic colloid increases by up to 40 degrees C compared to the pure liquid crystal host. A theoretical model is proposed in which the ferroelectric particles induce local dipoles whose effective interaction is proportional to the square ...


Undulations Of Lamellar Liquid Crystals In Cells With Finite Surface Anchoring Near And Well Above The Threshold, B. I. Senyuk, Ivan I. Smalyukh, Oleg Lavrentovich Jul 2006

Undulations Of Lamellar Liquid Crystals In Cells With Finite Surface Anchoring Near And Well Above The Threshold, B. I. Senyuk, Ivan I. Smalyukh, Oleg Lavrentovich

Chemical Physics Publications

We study the undulations instability, also known as the Helfrich-Hurault or layers buckling effect, in a cholesteric liquid crystal confined between two parallel plates and caused by an electric field applied along the normal to layers. The cholesteric pitch is much smaller than the cell thickness but sufficiently large for optical study. The three-dimensional patterns of the undulating layers in the bulk and at the surfaces of the cells are determined by fluorescence confocal polarizing microscopy. We demonstrate that the finite surface anchoring at the bounding plates plays a crucial role in the system behavior both near and well above ...


Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds With Columnar And Synclinic Antiferroelectric Layered Phases, Channabasaveshwar V. Yelamaggad, Indudhara Swamy Shashikala, Uma S. Hiremath, Guangxun Liao, Antal Jakli, Doddamane S. Shankar Rao, Subbarao Krishna Prasad, Quan Li Jul 2006

Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds With Columnar And Synclinic Antiferroelectric Layered Phases, Channabasaveshwar V. Yelamaggad, Indudhara Swamy Shashikala, Uma S. Hiremath, Guangxun Liao, Antal Jakli, Doddamane S. Shankar Rao, Subbarao Krishna Prasad, Quan Li

Chemical Physics Publications

The phase transitional behavior of two homologous series of five-ring banana-shaped compounds comprising fluorine substituents synthesized through covalent linking of two chemically dissimilar rod-like anisometric cores (arms) to central 1,3-phenylene is reported. The novelty of these molecules originates from the fact that the molecules are highly nonsymmetrical. One of the arms, which is either salicylaldimine or Schiff base core, possesses two vicinal fluorine atoms at the terminal ring having a n-decyloxy tail; while the n-alkyl tail attached to the other arm was varied to realize a homologous series of compounds. The mesophases have been characterized by several complementary studies ...


Electric Heating Effects In Nematic Liquid Crystals, Y. Yin, Sergij V. Shiyanovskii, Oleg Lavrentovich Jul 2006

Electric Heating Effects In Nematic Liquid Crystals, Y. Yin, Sergij V. Shiyanovskii, Oleg Lavrentovich

Chemical Physics Publications

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 ...


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 Jul 2006

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

Chemistry & Biochemistry Publications

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.


Patterned Field Induced Polymer Walls For Smectic A Bistable Flexible Displays, N. Gheorghiu, John L. West, A. V. Glushchenko, M. Mitrokhin Jun 2006

Patterned Field Induced Polymer Walls For Smectic A Bistable Flexible Displays, N. Gheorghiu, John L. West, A. V. Glushchenko, M. Mitrokhin

Chemistry & Biochemistry Publications

We have obtained a polymer wall-stabilized smectic A liquid crystal to be used for bistable flexible displays. The polymer wall structure optimally connects the two substrates together, thus providing maximum flexibility as compared to the polymer dispersed liquid crystal. Moreover, all the intrinsic bistable properties of the smectic A material are preserved. We analyzed the pixel performance and demonstrated very good electro-optical characteristics, high contrast ratio, and excellent stability of the states. The polymer wall-stabilized smectic A on flexible substrates has high potential to be used as electronic paper.


Electric Field Dependence Of The Electric Conductivity In Liquid Crystals Made Of Bent-Core Molecules, O. G. Martins, G. Barbero, A. M. Pedreira, Antal Jakli, H. Sawade, A. M. F. Neto May 2006

Electric Field Dependence Of The Electric Conductivity In Liquid Crystals Made Of Bent-Core Molecules, O. G. Martins, G. Barbero, A. M. Pedreira, Antal Jakli, H. Sawade, A. M. F. Neto

Chemical Physics Publications

We investigate the influence of the electric field on the conductivity of an antiferroelectric liquid crystal formed by bananalike molecules. Our experimental analysis shows that large deviations of the current from a pure Ohmic behavior are observed for applied voltage of the order of the ones used for the determination of the spontaneous polarization in these types of materials. The measurements are performed in the isotropic and B-2 phases. In the isotropic phase these deviations are interpreted in terms of the model proposed by Onsager, according to which, for weak electrolyte, the conductivity depends on the actual electric field present ...


Structure And Dynamics Of Liquid Crystalline Pattern Formation In Drying Droplets Of Dna, Ivan I. Smalyukh, O. V. Zribi, Jc Butler, Oleg Lavrentovich, G.C.L. Wong May 2006

Structure And Dynamics Of Liquid Crystalline Pattern Formation In Drying Droplets Of Dna, Ivan I. Smalyukh, O. V. Zribi, Jc Butler, Oleg Lavrentovich, G.C.L. Wong

Chemical Physics Publications

We investigate the formation of ringlike deposits in drying drops of DNA. In analogy with the colloidal "coffee rings," DNA is transported to the perimeter by the capillary flow. At the droplet edge, however, DNA forms a lyotropic liquid crystal (LC) with concentric chain orientations to minimize the LC elastic energy. During the final stages of drying, the contact line retracts, and the radial stress causes undulations at the rim that propagate inward through the LC and form a periodic zigzag structure. We examine the phenomenon in terms of a simple model based on LC elasticity.


Ferroelectricity Of A Bent-Core Material With Cholesteryl Terminal Chain, Guangxun Liao, Indudhara Swami Shashikala, Channabasaveshwar V. Yelamaggad, Doddamane S. Shankar Rao, Subbarao Krishna Prasad, Antal Jákli May 2006

Ferroelectricity Of A Bent-Core Material With Cholesteryl Terminal Chain, Guangxun Liao, Indudhara Swami Shashikala, Channabasaveshwar V. Yelamaggad, Doddamane S. Shankar Rao, Subbarao Krishna Prasad, Antal Jákli

Chemical Physics Publications

We have studied the phase sequence and physical properties of an asymmetric bent-core material with a chiral rigid cholesteryl moiety, and a flexible achiral alkyl side chain at the other end. The combination of the achiral bent core with the chiral cholesteryl unit results in properties different from those of both the usual calamitic and bent-core materials. We find that the presence of the bent core unit induces a wide-temperature-range optically isotropic (probably BPIII) mesophase between the isotropic and cholesteric (chiral nematic) phases. Below the cholesteric phase a ferroelectric smectic-C-* structure occurs in which the bent-core units do not seem ...


Smectic-A-Filled Birefringent Elements And Fast Switching Twisted Dual-Frequency Nematic Cells Used For Digital Light Deflection, Oleg Pishnyak, Andrii Golovin, Liubov Kreminska, John J. Pouch, Felix A. Miranda, Bruce K. Winker, Oleg Lavrentovich Apr 2006

Smectic-A-Filled Birefringent Elements And Fast Switching Twisted Dual-Frequency Nematic Cells Used For Digital Light Deflection, Oleg Pishnyak, Andrii Golovin, Liubov Kreminska, John J. Pouch, Felix A. Miranda, Bruce K. Winker, Oleg Lavrentovich

Chemical Physics Publications

We describe the application of smectic A (SmA) liquid crystals for beam deflection. SmA materials can be used in digital beam deflectors (DBDs) as fillers for passive birefringent prisms. SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Fast rotation of the incident light polarization in DBDs is achieved by an electrically switched 90-deg twisted nematic (TN) cell.


Critical Behavior At The Isotropic-To-Nematic Phase Transition In A Bent-Core Liquid Crystal, D. B. Wiant, S. Stojadinovic, K. Neupane, S. Sharma, Katalin Fodor-Csorba, Antal Jakli, Jim T. Gleeson, Samuel N. Sprunt Mar 2006

Critical Behavior At The Isotropic-To-Nematic Phase Transition In A Bent-Core Liquid Crystal, D. B. Wiant, S. Stojadinovic, K. Neupane, S. Sharma, Katalin Fodor-Csorba, Antal Jakli, Jim T. Gleeson, Samuel N. Sprunt

Chemical Physics Publications

Magnetic birefringence and dynamic light scattering measurements of orientational order parameter fluctuations at the isotropic-nematic phase transition of a bent-core liquid crystal reveal a pretransitional temperature dependence consistent with the standard Landau-deGennes mean field theory. However, as follows: the transition in the bent-core compound is more weakly first order (T(NI)-T(*)approximate to 0.4 degrees C), the leading Landau coefficient is similar to 30 times lower, the viscosity associated with nematic order fluctuations is similar to 10 times higher, and the density change is similar to 10 times lower, than typically observed in calamitic (rod-shaped) liquid crystals. One ...


Directed Vertical Alignment Liquid Crystal Display With Fast Switching, Mingxia Gu, Ivan I. Smalyukh, Oleg Lavrentovich Feb 2006

Directed Vertical Alignment Liquid Crystal Display With Fast Switching, Mingxia Gu, Ivan I. Smalyukh, Oleg Lavrentovich

Chemical Physics Publications

We describe a directed vertical alignment (VA) display mode based on a nematic liquid crystal (LC) doped with a chiral dopant and confined between two substrates, one of which is pretreated, say, by unidirectional rubbing or photoalignment. The design allows one to eliminate umbilical defects that appear during switching of the conventional VA cells and thus to obtain better contrast. Switching is similar to 30% faster than for VA cells when optimized concentration of a chiral dopant is added and LC molecules at one of the substrates are slightly tilted from the cell normal due to the unidirectional surface treatment.


Improved Liquid Crystals For Vertical Alignment Applications, Cheng Chen, Philip J. Bos, Julie Kim, Quan Li, James E. Anderson Jan 2006

Improved Liquid Crystals For Vertical Alignment Applications, Cheng Chen, Philip J. Bos, Julie Kim, Quan Li, James E. Anderson

Chemical Physics Publications

Liquid crystals with a large negative dielectricanisotropy are difficult to align vertically on silicon oxide surfaces and sometimes even on polyimides. An interesting method has been found to generate high quality vertical alignment by doping the host liquid crystal with materials that have a cyanogroup along their long molecular axis. The effect is explained by considering both long range and short range interactions between liquid crystal and the alignment layer. Using this method we propose a way to design new liquid crystal mixtures with large negative dielectricanisotropy that have improved aligning ability for applications requiring vertical alignment. The method also ...


Nonlocal Model For Nematic Liquid-Crystal Elastomers, R. Ennis, L. C. Malacarne, Peter Palffy-Muhoray, M. Shelley Jan 2006

Nonlocal Model For Nematic Liquid-Crystal Elastomers, R. Ennis, L. C. Malacarne, Peter Palffy-Muhoray, M. Shelley

Chemical Physics Publications

We have developed a fully nonlocal model to describe the dynamic behavior of nematic liquid-crystal elastomers. The free energy, incorporating both elastic and nematic contributions, is a function of the material displacement vector and the orientational order parameter tensor. The free energy cost of spatial variations of these order parameters is taken into account through nonlocal interactions rather than through the use of gradient expansions. We also give an expression for the Rayleigh dissipation function. The equations of motion for displacement and orientational order are obtained from the free energy and the dissipation function by the use of a Lagrangian ...