A4‐sized flexible ferroelectric liquid‐crystal displays with micro color filters

Abstract— We demonstrated an A4‐paper‐sized flexible ferroelectric liquid‐crystal (FLC) color displays fabricated by using a new plastic‐substrate‐based process which was developed for large‐sized devices. Finely patterned color filters and ITO electrodes were formed on a plastic substrate by a transfer method to avoid surface roughness and thermal distortion of the substrate, which induce disordering of the FLC molecular alignment. The thickness of an FLC/monomer solution sandwiched by two plastic‐film substrates was well controlled over a large area by using flexographic printing and lamination techniques. Molecular‐aligned polymer walls and fibers were formed in the FLC by a two‐step photopolymerization‐induced phase‐separation method using UV‐light irradiation. A fabricated A4‐sized flexible‐sheet display for color‐segment driving was able to exhibit color images even when it was bent.     

Liquid-crystal luminaire consisting of an optical shutter and a metal halide lamp

We made a liquid-crystal (LC) luminaire for the first time to our knowledge by combining a metal halide lamp and an optical shutter composed of a compound of a very high nematic-isotropic point (172 degrees C) LC and a polymer (CLCP). The shutter can modulate high-power light independently of the state of polarization because the CLCP film becomes transparent or opalescent when either sufficiently high or no voltage is applied to it. To solve the problem, which is peculiar to CLCP films, that the color temperature of light modulated by the film changes with the film's transmittance, a pulse-width modulation method that varies the time ratio of the on and off states of the shutter was developed. The performance characteristics of the luminaire were as follows: illuminance range, 192 to 10,400 lx at a distance of 5 m from the luminaire; rise and decay times, 1.4 and 1.5 ms; color temperature, 4060-5600 K; operation room temperature, ~150 degrees C; stable operation time, more than 2000 h. Experimental results show the feasibility of applications of this luminaire in various fields, including television, movie, and stage lighting.     

High-brightness projection display using spatial light modulatorswith polymer-dispersed liquid crystal

A brightness-enhanced full-color projection display using optically addressed spatial light modulators (SLMs) with light-scattering mode polymer-dispersed liquid crystal has been developed. The SLM can modulate strong unpolarized light efficiently using the light-scattering effect. The projector using SLM with a Schlieren optical system produces bright, high-contrast images. Electrical image compensation of the shading and gamma characteristics of the SLMs carried out in the driving circuits improves the spatial uniformity and grayscale representation of the projected images. The system projects a bright image of more than 1300 cd/m² with a high extinction ratio over 130:1 on a 60-inch screen, which can be viewed in a bright living room under normal lighting conditions     

Flexible ferroelectric liquid‐crystal devices containing fine polymer fibers

A new flexible ferroelectric liquid‐crystal‐display device with gray‐scale capability has been created by using submicrometer‐diameter polymer fibers. The polymer fibers, which are formed by photopolymerization of aligned monomer molecules in liquid crystal, align the ferroelectric liquid crystal and mechanically support two flexible thin plastic substrates. The composite film made of liquid crystal and polymer with a thickness of 2 μm was formed between the plastic substrates by using a fabrication method consisting of coating, lamination, and ultraviolet irradiation processes without the conventional gap‐forming and injection processes. The fabricated flexible device revealed gray‐scale capability due to the change in spatial distribution of micrometer‐sized binary‐switching liquid‐crystal domains. From the polarizing microscope observation, it was found that the switching domains are generated and expanded from the areas with poor polymer density. The experimental results indicated that the polymer fibers spatially modulate the threshold voltage for molecular switching. Our device exhibits great potential for flexible large‐sized light‐weight motion‐image displays.     

Analytical Model for Concrete Confined with Fiber Reinforced Polymer Composite

An analytical model to predict the behavior of concrete confined with fiber reinforced plastic (FRP) composites subjected to axial compressive loads was developed. First, a constitutive model for plain concrete was formulated from past experimental results obtained from triaxial compression tests of concrete, in which concrete specimens were maintained under constant confining stresses. This was an orthotropic constitutive model based on the concept of equivalent uniaxial strain. Subsequently, in the analytical model for FRP confined concrete, the proposed constitutive model for concrete materials was incorporated. The FRP was assumed to be a linear elastic material. Force equilibrium and strain compatibility between the concrete and the FRP as well were satisfied. When the proposed model was applied to FRP confined concrete, the model overestimated the axial stress. To rectify this, a subsequent maximum strength criterion was introduced to control the maximum strength in the postpeak region when confining stress was continuously increased. The proposed analytical model with the addition of the subsequent maximum strength criterion is in good agreement with the experimental results.     

Undershooting and set-reset operation in bistable laser diodes withinhomogeneous excitation

The effect of undershoot switching, downward switching from the upper to the lower state by undershooting caused by the rapid diminishing of the applied optical pulse, is analyzed for bistable laser diodes with inhomogeneous current injection. The height and width of the optical input pulse superposed on the optical bias are shown to play an important role in undershoot switching as well as the level of the optical bias. It is also shown that set-reset and the generation of the optical monostable pulse can be done by using undershoot switching     

Loss of H19 imprinting in esophageal cancer

Recent articles have reported that loss of imprinting (LOI) of the endogenous gene H19 was frequently found in lung cancer and chorio-carcinoma, common adulthood cancers. Consequently, we examined the status of genomic imprinting of H19 in 29 esophageal and 48 colorectal cancer specimens, and studied its relation to the expression of H19. Of 12 esophageal cancer specimens heterozygous for the RsaI polymorphism, 6 (50%) exhibited LOI of H19, but none of the 18 colorectal cancer specimens heterozygous for the RsaI polymorphism exhibited LOI of H19. The present study suggests that LOI of H19 may play an important role in the pathogenesis of esophageal cancer. Moreover, H19 expression was frequently abundant in both cancers, and all six esophageal cancers carried LOI with overexpressed H19. Therefore, this overexpression of H19 seems to be an important phenomenon for the development of esophageal and colorectal cancer cells.     

A simple approach to bifurcation and limit point calculations

A simple approach is proposed to calculate the bifurcation and limit points of structures, talcing into account the pre-unstable behaviour, by the finite element method. The approach is as follows: at each load step, the triangular factorization of the tangent stiffness matrix is checked to determine if the matrix is positive definite or not. When the tangent stiffness matrix is positive definite at a certain load step and non-positive definite at the next load step, the structure is considered to become unstable between the two load steps and an eigenproblem is constructed based on the difference of the tangent stiffness matrices at the two load steps. The critical load and corresponding mode of the structure are then derived from solving the eigenproblem. The proposed procedure is simple and economical, and it can be easily incorporated into a conventional geometric nonlinear analysis computer program. It is implemented in the ADINA program and some sample calculations are shown.     

The nitrogen gas tension test. Part 2: failure mechanism

In this study, the mechanism of concrete failure in the nitrogen gas tension test was investigated through a series of experiments. First, the nitrogen gas tension test was carried out two types of specimens: solid cylinders and hollow cylinders. The test results clearly showed that there was no significant difference in the gas pressure at failure between the solid specimen and the hollow specimen. Since a tension crack occurring on the surface of the concrete specimen at a gas pressure almost equal to the tensile strength of the concrete might play a key role in understanding the failure mechanism, a failure criterion based on linear elastic fracture mechanics (LEFM) was consequently developed. The nitrogen gas tension test was newly carried out on cylindrical specimens with circumferential notches of various depths. Though LEFM was found to be useful in developing an understanding of the mechanism of concrete failure, the experimental results indicated that it was not really valid for specimens with notch depths deeper than some critical size (critical notch depth). However, based on the experimental observation that the concrete specimen failed at its tensile strength at notch depths smaller than the critical notch depth, a modified LEFM based failure mechanism was proposed taking into account the notch sensitivity of the concrete.