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Yabu S.,Osaka University | Tanaka Y.,Osaka University | Tagashira K.,Osaka University | Yoshida H.,Osaka University | And 4 more authors.
Optics Letters | Year: 2011

Polarization-independent refractive index (RI) modulation can be achieved in blue phase (BP) liquid crystals (LCs) by applying an electric field parallel to the direction of light transmission. One of the problems limiting the achievable tuning range is the field-induced phase transition to the cholesteric phase, which is birefringent and chiral. Here we report the RI modulation capabilities of gold nanoparticle-doped BPs I and II, and we show that field-induced BP-cholesteric transition is suppressed in nanoparticle-doped BP II. Because the LC remains optically isotropic even at high applied voltages, a larger RI tuning range can be achieved. © 2011 Optical Society of America. Source


Inoue Y.,Osaka University | Yoshida H.,Osaka University | Yoshida H.,Japan Science and Technology Corporation JST | Inoue K.,Osaka University | And 4 more authors.
Advanced Materials | Year: 2011

Continuous tuning of lasing wavelength is achieved in cholesteric liquid crystal lasers by embedding a network of nanopores with an average size of 10 nm filled with liquid crystals inside a polymerized matrix with helical order. The device possesses both high transparency and a fast response time because the tuning is driven by local reorientation of the liquid crystal molecules in the nanopores. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Taniguchi Y.,Japan Advanced Institute of Science and Technology | Khatri B.S.,University of Edinburgh | Brockwell D.J.,University of Leeds | Paci E.,University of Leeds | And 2 more authors.
Biophysical Journal | Year: 2010

The motor protein myosin II plays a crucial role in muscle contraction. The mechanical properties of its coiled-coil region, the myosin rod, are important for effective force transduction during muscle function. Previous studies have investigated the static elastic response of the myosin rod. However, analogous to the study of macroscopic complex fluids, how myosin will respond to physiological time-dependent loads can only be understood from its viscoelastic response. Here, we apply atomic force microscopy using a magnetically driven oscillating cantilever to measure the dissipative properties of single myosin rods that provide unique dynamical information about the coiled-coil structure as a function of force. We find that the friction constant of the single myosin rod has a highly nontrivial variation with force; in particular, the single-molecule friction constant is reduced dramatically and increases again as it passes through the coiled-uncoiled transition. This is a direct indication of a large freeenergy barrier to uncoiling, which may be related to a fine-tuned dynamic mechanosignaling response to large and unexpected physiological loads. Further, from the critical force at which the minimum in friction occurs we determine the asymmetry of the bistable landscape that controls uncoiling of the coiled coil. This work highlights the sensitivity of the dissipative signal in force unfolding to dynamic molecular structure that is hidden to the elastic signal. © 2010 by the Biophysical Society. Source


Yoshida H.,Osaka University | Yoshida H.,Japan Science and Technology Corporation JST | Yabu S.,Osaka University | Tone H.,Osaka University | And 3 more authors.
Optical Materials Express | Year: 2014

The electro-optic Kerr effect in cubic blue phase liquid crystals comprises two components with different characteristic response times: one attributed to the primary (purely electro-optic) effect and another attributed to the secondary, or indirect (photoelastic) effect. Through simultaneous measurement of the polarized reflection spectrum and transmitted phase, we show that the contribution of the secondary electro-optic effect can be as large as 20% of the total change in refractive index, and that it is suppressed in the polymer-stabilized blue phase. Our results show the importance of stabilizing the lattice structure to realize blue-phase devices with fast response. © 2014 Optical Society of America. Source


Yoshida H.,Osaka University | Yoshida H.,Japan Science and Technology Corporation JST | Yabu S.,Osaka University | Tone H.,Osaka University | And 2 more authors.
Applied Physics Express | Year: 2013

The electro-optic properties of cholesteric blue phase (BP) liquid crystals is investigated by two-beam interference microscopy. The technique can facilitate the evaluation of BP materials, since only a single measurement is required to determine the two important electro-optic coefficients, i.e., the Kerr and electrostriction coefficients, of BPs. Moreover, field-induced symmetry transitions can be observed microscopically, making this a powerful tool to investigate the structure-property relationship in BPs. Herein, we observe field-induced transitions from cubic BPs I and II to the centered tetragonal BP X, and investigate the influence of this transition on the Kerr coefficient. © 2013 The Japan Society of Applied Physics. Source

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