Omnidirectional color wavelength tuning of stretchable chiral liquid crystal elastomers.

Wavelength-tunable structural colors using stimuli-responsive materials, such as chiral liquid crystals (CLCs), have attracted increasing attention owing to their high functionality in various tunable photonic applications. Ideally, on-demand omnidirectional wavelength control is highly desirable from the perspective of wavelength-tuning freedom. However, despite numerous previous research efforts on tunable CLC structural colors, only mono-directional wavelength tuning toward shorter wavelengths has been employed in most studies to date. In this study, we report the ideally desired omnidirectional wavelength control toward longer and shorter wavelengths with significantly improved tunability over a broadband wavelength range. By using areal expanding and contractive strain control of dielectric elastomer actuators (DEAs) with chiral liquid crystal elastomers (CLCEs), simultaneous and omnidirectional structural color-tuning control was achieved. This breakthrough in omnidirectional wavelength control enhances the achievable tuning freedom and versatility, making it applicable to a broad range of high-functional photonic applications.

Analytical investigation of multi-layered rollable displays considering nonlinear elastic adhesive interfaces.

To design the multilayered structures of reliable rollable displays, finite element method (FEM) investigations are conducted at various rolling conditions. Given that the optically clear adhesive (OCA) is the only flexible component and interfacial layer that plays an important role in allowing flexibility in rollable displays, we investigated its nonlinear elastic properties in detail. Hereto, FEM of rollable displays have been limited and inaccurate because OCA has been assumed to be a linear elastic material. In addition, despite the fact that rolling deformation exhibits complex bending characteristics, unlike folding, the mechanical behaviors over the entire area of rollable displays at all positions have not yet been addressed. In this study, we describe the dynamic and mechanical characteristics of rollable displays at all positions considering the hyperelastic and viscoelastic properties of OCA. The maximum normal strain of the rollable displays was applied about 0.98%, and the maximum shear strain of the OCA was shown to be around 720%. To assess the stability of the rollable displays, normal and yield strains were compared to each layer and investigated. Consequently, mechanical modeling of the rollable displays was conducted and stable rolling behaviors that did not cause permanent deformation were investigated.

Color-Tuning Mechanism of Electrically Stretchable Photonic Organogels.

In contrast to nano-processed rigid photonic crystals with fixed structures, soft photonic organic hydrogel beads with dielectric nanostructures possess advanced capabilities, such as stimuli-responsive deformation and photonic wavelength color changes. Recenlty, advanced from well-investigated mechanochromic method, an electromechanical stress approach is used to demonstrate electrically induced mechanical color shifts in soft organic photonic hydrogel beads. To better understand the electrically stretchable color change functionality in such soft organic photonic hydrogel systems, the electromechanical wavelength-tuning mechanism is comprehensively investigated in this study. By employing controllable electroactive dielectric elastomeric actuators, the discoloration wavelength-tuning process of an electrically stretchable photonic organogel is carefully examined. Based on the experimental in-situ response of electrically stretchable nano-spherical polystyrene hydrogel beads, the color change mechanism is meticulously analyzed. Further, changes in the nanostructure of the symmetrically and electrically stretchable organogel are analytically investigated through simulations of its hexagonal close-packed (HCP) lattice model. Detailed photonic wavelength control factors, such as the refractive index of dielectric materials, lattice diffraction, and bead distance in an organogel lattice, are theoretically studied. Herein, the switcing mechanism of electrically stretchable mechanochromic photonic organogels with photonic stopband-tuning features are suggested for the first time.

Influence of combined therapy with conventional and herbal medicines on liver function in 138 inpatients with abnormal liver transaminase levels.

BACKGROUND: To evaluate the influence of combined therapy of conventional and herbal medicines on liver function. METHODS: This study was a retrospective chart review. A total of 138 patients with abnormal liver transaminase levels at the time of admission were included in this study. We evaluated the influence of combined therapy of conventional and herbal medicines on liver transaminase levels over a period of at least 2 weeks at Kyung Hee University Korean Medical Hospital. Analyses were performed using SPSS version 17.0 for Windows. Paired T-tests were used to examine the significance of differences in AST, ALT, and GGT levels at the time of admission and discharge. RESULTS: We found that combined therapy reduced levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma glutamyl transferase (GGT) to a statistically significant level. Specifically, there were 48, 66, 104 subjects who exhibited abnormal AST, ALT and GGT levels at admission, which was reduced to 13, 37, and 64 subjects after combined therapy, respectively. Some subjects exhibited worsening levels of liver transaminases after combined therapy, so we used the χ2 test to analyze the influence of combined therapy with conventional and herbal medicines on liver function according to initial liver transaminase levels. According to this analysis, ALT and GGT levels may be more important than AST levels in estimating the influence of combined therapy on patients with abnormal liver transaminase levels. CONCLUSIONS: Based on this retrospective chart review, combined therapy of conventional and herbal medicines would be considered relatively safe. Thus, if patients have abnormal ALT or GGT levels, caution should be taken when suggesting combined therapy with conventional and herbal medicines.