LC Cell Research Articles

Perylene-Based Chromophore as a Versatile Dye for Light Amplification.

One of the challenges for modern optoelectronics is to find versatile, easily adaptable components for novel laser-based technologies. A very attractive perylene-derivative chromophore in different organic matrices for high-performance light amplification is discussed and outlined. Our approach demonstrates the outstandingly compatible laser dye and a viable strategy to provide an effective optical gain for stimulated emission enhancement. Through structural control, we produce simple optical devices embedded in organic matrices, such as poly(methyl methacrylate), nematic liquid crystalline (NLC) mixture, and a hybrid emulsion system (poly(vinyl alcohol) PVA + NLC mesophase). Importantly, we investigate and compare the spectroscopy of differently constructed organic systems in terms of stimulated-emission thresholds and light amplification process efficiency. Moreover, we report the effects of tunability for LC cells by an applied external electric field stimulus. Future directions of laser systems are outlined with an emphasis on the role of the perylene derivative. The studies meet current challenges in the field of modern organic technologies dedicated to various optoelectronic systems, including touch screens, displays, and Li-Fi networks.

Synthesis and physicochemical studies of double fluorinated hydrogen-bonded liquid crystals (n-OBAFF)

Hydrogen Bound Liquid Crystals (HBLCs) have been the subject of intensive research by many research groups due to its effects on liquid crystal displays. In this work, three fluorinated HBLCs of n-alkyloxy-2,3-difluorobenzoic acid (n-OBAFF) were synthesized with different “n” chain lengths (n = 10, n = 11 and n = 12). The synthesized compounds were studied by elemental analysis and Fourier transform infrared spectroscopy (FT-IR). Their thermal and phase behavior were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The dielectric properties of n-OBAFF were examined in the frequency range 1 to 106 Hz. The parameters of a suitable suggested equivalent circuit were then determined. Next, the Nernst distance and LC cell scattering coefficient, along with other metric parameters, were calculated and discussed.

Modulation of Chirality and Intensity of Circularly Polarized Luminescence Emitting from Cholesteric Liquid Crystals Triggered by Photoresponsive Molecular Motor

AbstractA chiral‐switchable device for circularly polarized luminescence (CPL) is fabricated based on dynamic superstructure of cholesteric liquid crystals (N*‐LC) doped with light‐driven molecular motor (MM), which achieves simultaneous modulation of chirality and intensity of CPL. Functional MM, designed with the modification of alkyl chains on the rotor, allows for advanced chemical isomerization to be driven with light. The selective reflection band due to the N*‐LC is shifted upon UV irradiation so that the reflection band moves toward the emissive band of the luminescence dyes, yielding CPL with opposite handedness and high dissymmetry factor values. The geometric changes of the motor during the rotary steps finally cause a remarkable reversible handedness inversion of the N*‐LC, which also leads switchable chirality of CPL. The dynamic N*‐LC cell bearing the light‐controlled selective reflection is useful for generating CPL from fluorescent materials and for allowing light chirality‐switching in CPL signals, which presents new possibilities for optoelectronic and photonics applications.

A model of impaired Langerhans cell maturation associated with HPV induced epithelial hyperplasia

SummaryLangerhans cells (LC) are skin-resident antigen-presenting cells that regulate immune responses to epithelial microorganisms. Human papillomavirus (HPV) infection can promote malignant epithelial transformation. As LCs are considered important for controlling HPV infection, we compared the transcriptome of murine LCs from skin transformed by K14E7 oncoprotein and from healthy skin. We identified transcriptome heterogeneity at the single cell level amongst LCs in normal skin, associated with ontogeny, cell cycle, and maturation. We identified a balanced co-existence of immune-stimulatory and immune-inhibitory LC cell states in normal skin that was significantly disturbed in HPV16 E7-transformed skin. Hyperplastic skin was depleted of immune-stimulatory LCs and enriched for LCs with an immune-inhibitory gene signature, and LC-keratinocyte crosstalk was dysregulated. We identified reduced expression of interleukin (IL)-34, a critical molecule for LC homeostasis. Enrichment of an immune-inhibitory LC gene signature and reduced levels of epithelial IL-34 were also found in human HPV-associated cervical epithelial cancers.

Dependence of the integral characteristics of a nematic light modulator on the physical parameters of a liquid crystal

In the present work, the effect of physical constants of an LC material on the integral characteristics of a modulator operating in a waveguide mode in an LC structure with a twist angle of 270 and antisymmetric boundary conditions in the working cell was studied using the method of computer simulation. It is shown that, under antisymmetric boundary conditions, the small value of the total response time of the LC modulator is due to the absence of a “backflow” in the LC cell and the role of only half of the LC working gap thickness in the dynamics of switching between two states in such a device. In addition, it was found that in order to simultaneously achieve high contrast ratios and a short total response time of the device, it is necessary to choose an LC material with a high value of its dielectric anisotropy. In this case, there is an optimal set of elasticity constants for the LC material, which simultaneously realizes a high contrast ratio and a short total response time of the modulator.

Structural changes in liquid crystals doped with spindle magnetic particles

A new composite ferronematic system based on the nematic liquid crystal 6CB doped with hematite spindle-like magnetic particles characterized with magnetic moments oriented perpendicularly to their main axes was prepared. The surface acoustic waves (SAWs) were used to study the effect of magnetic particles on liquid crystals' structural changes in a magnetic field using measurements of the attenuation of SAW propagating along the ferronematic liquid crystal surface. For a study of new composite materials' orientational properties, the ferronematic samples were prepared with three different lengths of the particles and with the volume concentrations of particles φ1 = 10−3, φ2 = 10−4, and φ3 = 10−5. SAW attenuation response to the external magnetic field was investigated experimentally for two different directions of the magnetic field regarding the cell position, perpendicular and/or parallel to the LC cell. Experimental results validated a decrease of the threshold field in the ferronematic samples in comparison with the pure 6CB for the field in a perpendicular direction and an increase of the threshold shift with a growth of both the volume fraction of solid impurity and the length of particles for magnetic field applied perpendicularly to the cell plane. The effect of particle concentration on the magnitude of structural changes and also on the large residual attenuation at decreasing the magnetic field was observed in this arrangement. The parallel magnetic field direction led to the similar behavior of investigated ferronematic systems in early studied magnetic particles and provided switching processes.

A cholesteric liquid crystal smart window with a low operating voltage

A dye-doped cholesteric liquid crystal smart window with a haze-free opaque state is demonstrated. We designed a random stripe pattern in the cholesteric phase, known as the fingerprint (FP) texture, as an initial state (opaque state). In the theoretical calculation of the LC alignment states, although the transmittance of the FP state is slightly higher than that of the twisted state (planar state), it is much lower than homogeneously aligned states. Moreover, we confirmed the proposed LC cell shows the lowest operating voltage (4 V) among guest-host liquid crystal cells because of vertical anchoring at the surfaces.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Positive Effects of Highly Graphitized Porous Carbon Loaded with PbO on Cycle Performance of Negative Plates of Lead-Acid Batteries

Carbon materials are one of the most important additives used in lead-acid batteries (LABs) to solve irreversible sulfation. Being the next generation additive for LABs, they exhibit more excellent performance. The addition of carbon materials to negative active material (NAM) is used to enhance the performance of batteries. In this paper, the composite of lead oxide and carbon (LC) was prepared by the pyrolysis of a mixture of highly graphitized porous carbon (HPC) and PbCO3. Compared with the control cell, the initial specific discharge capacity was increased by 16.5% when LC material was added to NAM. Finally, a possible mechanism for the improvement of the cycle performance of LC cell was proposed. The adoption of LC material can eliminate the difference in density between Pb and C, and thus make them evenly mixed. The uniformly dispersed HPC can promote electrolyte circulation and effectively limit the overgrowth of irreversible PbSO4. At the same time, the presence of -Pb-COO chemical bond can strengthen the stability of lead-carbon electrodes.

Fabrication of optical vortex array by fixing standing wave mediated periodic defects in nematic liquid crystals via photopolymerization

ABSTRACT Optical vortex beams have attracted significant research interest owing to their potential for application in optical communication and imaging. In this study, we demonstrated devices with electrically switchable topological defects as well as those with permanent topological defects using reactive mesogen (RM) and vertically aligned LC cells. A defect array was created via standing wave-mediated periodic LC orientation control by applying pulse train waves. At a low RM concentration (0.6 wt%), polymerisation induced a pretilt angle, and the periodic LC alignment was memorised with a topological defect array. Thus, the memorised defect structure reappeared upon applying a direct current field or standard square electric fields. In contrast, at a high RM concentration (3 wt.%), a permanent defect array device was realised. Thus, depending on the RM concentration, various types of defect arrays were selectively created. The devices developed in this study can be used for various potential applications, such as in digital data transfer and imaging systems.

Wide-temperature-range liquid-crystal display with liquid-crystal material of negative dielectric anisotropy

A vertical alignment mode liquid-crystal display (VA-LCD) with a wide nematic temperature range was developed in this work. For development of this LC cell, a negative dielectric anisotropy liquid-crystal material (nega-LCM) with wide nematic temperature range from −40 to +90 °C (nega-WNT-LCM) was selected. The fabricated VA mode LC cell showed twice faster response time at −20 °C compared with the conventional negative-type LCM, and significantly high contrast ratio (2910:1). In addition, the VA mode LC cell with the nega-WNT-LCM would be used in a severe environment with remarkably high- and low-temperature region. Thus, the developed VA mode LC cell would be useful for outdoor-use applications, such as the automotive application.

A Novel Technique for Determination of Residual Direct-Current Voltage of Liquid Crystal Cells with Vertical and In-Plane Electric Fields

Generation of residual direct-current (DC) voltage (VrDC) induces serious image sticking of liquid crystal displays (LCDs). In this study, a novel technique to determine the VrDC of LC cells is proposed. We found that the VrDC could be determined from a current-voltage (I-V) curve obtained by the application of triangular voltage. In the case of a vertically aligned twisted nematic (VTN) mode LC cell, where a vertical electric field is applied, the I-V curve shows maximum and minimum current peaks owing to rotation of an LC director, and the VrDC is able to be determined from an average value of the two peaks. On the other hand, in the case of a fringe field switching (FFS) mode LC cell, where an in-plane (lateral) electric field is applied from comb electrodes, the current peaks derived from the rotation of the LC director do not appear. Therefore, we could not adopt the same way with that of the VTN mode LC cell. However, we found that there were two minimum current peaks derived from minimum capacitances of the FFS mode LC cell, and could determine the VrDC by using these two current peaks. The proposed technique would be useful for the evaluation of the VrDC of the LCDs, where the electric field is applied both vertically and laterally.

Inhibition of Jumonji Histone Demethylases Selectively Suppresses HER2+ Breast Leptomeningeal Carcinomatosis Growth via Inhibition of GMCSF Expression.

HER2+ breast leptomeningeal carcinomatosis (HER2+ LC) occurs when tumor cells spread to cerebrospinal fluid-containing leptomeninges surrounding the brain and spinal cord, a complication with a dire prognosis. HER2+ LC remains incurable, with few treatment options. Currently, much effort is devoted toward development of therapies that target mutations. However, targeting epigenetic or transcriptional states of HER2+ LC tumors might efficiently target HER2+ LC growth via inhibition of oncogenic signaling; this approach remains promising but is less explored. To test this possibility, we established primary HER2+ LC (Lepto) cell lines from nodular HER2+ LC tissues. These lines are phenotypically CD326+CD49f-, confirming that they are derived from HER2+ LC tumors, and express surface CD44+CD24-, a cancer stem cell (CSC) phenotype. Like CSCs, Lepto lines showed greater drug resistance and more aggressive behavior compared with other HER2+ breast cancer lines in vitro and in vivo. Interestingly, the three Lepto lines overexpressed Jumonji domain-containing histone lysine demethylases KDM4A/4C. Treatment with JIB04, a selective inhibitor of Jumonji demethylases, or genetic loss of function of KDM4A/4C induced apoptosis and cell-cycle arrest and reduced Lepto cell viability, tumorsphere formation, regrowth, and invasion in vitro. JIB04 treatment of patient-derived xenograft mouse models in vivo reduced HER2+ LC tumor growth and prolonged animal survival. Mechanistically, KDM4A/4C inhibition downregulated GMCSF expression and prevented GMCSF-dependent Lepto cell proliferation. Collectively, these results establish KDM4A/4C as a viable therapeutic target in HER2+ LC and spotlight the benefits of targeting the tumorigenic transcriptional network. SIGNIFICANCE: HER2+ LC tumors overexpress KDM4A/4C and are sensitive to the Jumonji demethylase inhibitor JIB04, which reduces the viability of primary HER2+ LC cells and increases survival in mouse models.

P‐55: Analysis of Bonding Optically Clear Adhesive in Dual‐Cell LCD

By bonding two pieces of LC cell, a dual‐cell LCD can efficiently reduce light leakage and greatly increase contrast ration. Bonding optically clear adhesive (OCA) should provide enough adhesion strength and present no influence on optical performance. Based on von Mises criteria, the paper employs finite element simulation to conclude that the thickness of OCA should be larger than 0.15mm for a 65in dual‐cell LCD. With the help of LCD design software, it is found that the optical performance of a 65in dual‐cell LCD has no obvious changes when the OCA thickness is less than 0.35mm The paper introduces an effective method to help analyze OCA effect on both adhesion strength and optical performance.

Bim's Effect on the Expression of miR-423-3p in Promoting Primary Hepatic Cancer (PHC) and Role of miR-423-3p in PHC Proliferation and Invasion.

In this study, we analyzed the miR-423-3p expression in primary hepatic cancer (PHC), its effect on cell proliferation, and migration and explored Bcl-2-interacting mediator effect on the role of miR-423-3p in promoting liver cancer. The miR-423-3p expression levels in LC tissues and adjacent non-tumor tissues were compared, and the relationship between miR-423-3p and clinical pathological characteristics of patients was analyzed. These levels in peripheral blood of LC patients and healthy volunteers were compared, and the diagnostic value of miR-423-3p in LC was analyzed. The miR-423-3p and BCL-2-interacting mediators of cell death (Bim) expression in LC cells SMMC-7721 and Huh-7 were analyzed. The changes of cell proliferation, invasion, and apoptosis level were evaluated. Furthermore, the association and regulatory relationship between miR-423-3p and Bim were evaluated by dual luciferase report. The miR-423-3p expression level in LC increased, indicating miR-423-3p could be a diagnostic marker for LC. miR-423-3p expression was relatively low in patients with low TNM stage (I-II) and LC with serum AFP level ≤ 20μg/L, related to the 5-year survival rate of LC patients. The 5-year survival rate of patients with low miR-423-3p expression was dramatically higher than that of those with high miR-423-3p expression. The miR-423-3p can promote proliferation and migration of LC cells and inhibit apoptosis, Bim can inhibit their growth and metastasis, and miR-423-3p can also regulate Bim expression. The miR-423-3p expression level in LC increased and could inhibit Bim to promote the proliferation and invasion of LC cells and inhibit apoptosis.

Rectangular current pulse generator to test varistors with pulsed electrical load

A brand-new circuit of a rectangular pulse current generator is presented. As a rule, generators consisting of 6-10 LC cells connected in series are used to obtain rectangular current pulses. Such units are very cumbersome and complicated in the selection of element parameters and adjustment, so a new scheme of pulse current generator was proposed. The main difference from the classical circuit is the method of generating a rectangular current pulse, i.e. by adding the currents from two parallel circuits connected to the load. The first circuit at discharge generates an aperiodic current pulse, the second generates an oscillatory current pulse. The total current pulse flowing through varistor has constant amplitude for some time. In a specified period of time, while the current pulse has a constant amplitude, there is an interruption of current with the help of a switching device. The given circuit solution is possible to implement when using fundamentally new switching devices of the IGBT module. A connection diagram of a pulse current generator for testing varistors with a classification voltage to 1200 V with adjustable pulse duration of 50, 1000, 2000 µs is proposed. The parameters of the generator circuit elements are determined. The measures aimed at suppression of overvoltages arising at break of current in circuits with high inductance as well as the tests confirming the operability of the designed circuit are carried out.

Label-free single-substrate quantitative protein assay based on optical characteristics of cholesteric liquid crystals

Cholesteric liquid crystal (CLC) is characterized by the selective reflection in the Bragg condition for constructive interference. Instead of assembling a LC cell with a pair of glass substrates, only a single glass substrate modified with vertical alignment reagent and layered with a CLC film of 3.4 ± 0.2 μm in thickness was utilized in this study for the detection of bovine serum albumin (BSA). By fine-tuning the ratio of the thickness d to the helical pitch P of the CLC film, both qualitative and quantitative biosensing capabilities were demonstrated with an E7/R811 CLC (d/P close to but smaller than unity) and an E7/R5011 CLC (d/P > > 1) film, respectively. The E7/R811 film was in the unwound homeotropic state in the absence of BSA, but transitioned to the fingerprint state at 10−9 to 10−6-g/ml BSA and to the planar state between 10−5 and 10−2-g/ml BSA. Quantitative protein assay based on E7/R5011 CLCs was established through transmission spectrometric analysis, and detection sensitivity was optimized by adjusting the Bragg reflection wavelength. A limit of detection of 5.9 × 10−9 g/ml was achieved for the CLC film consisting of 2.0-wt% R5011 in the nematic host E7 and exhibiting a Bragg reflection wavelength of 700 nm. As a majority of clinical assays are performed on a single solid substrate, the CLC-based, single-substrate biosensing platform allows for better integration with current technologies. Besides, the protein array employed in this work can be further miniaturized and converted to a protein microarray format to facilitate high-throughput analysis.

32.2: Controllable Viewing Angle Luminance for Super‐Fine‐TFT LCDs

In this letter, A continuously controllable viewing angle liquid crystal display, integrated with two LC cells(display cell and controlling cell), has been demonstrated to display information selectively at one side. The proposed device achieves asymmetric NVA(narrow viewing angle) luminance in private (only right side is visible,) mode, and symmetric WVA(wide viewing angle) luminance in common(left and right) mode by using novel LC and designing inside the viewing angle controlling cell. In NVA mode, Luminance at left side will be eliminated mostly while luminance at the other side remains. This technology meet the requirements of automotive premium CID(Center Information Display) or PID(Passenger Information Display) perfectly well, since it can provide good visual performance for the passenger, while preventing the driver to see any contents on the screen.

The scientific duo of TiO2 nanoparticles and nematic liquid crystal E204: Increased absorbance, photoluminescence quenching and improving response time for electro-optical devices

The present investigation on the dielectric and electro-optical properties of nematic liquid crystal (NLC) E204 and TiO2 nanocomposites has been carried out with a wide range of frequencies. The low-frequency spectra of these composites with a concentration of 0.1 wt/wt%, 0.5 wt/wt%, and 1.0 wt/wt% are recorded in the frequency range of 50–1000 Hz, and the content of impurity ions in these samples has been analyzed. The ion trapping by adsorbing sites of TiO2 and that effect on DC conductivity and diffusion constant have also been investigated. TiO2-doped LC cell results in a two-fold faster response time of the pure LC cell, as a consequence of a remarkable reduction in the rotational viscosity of the LCs. The change in the intensity of the photoluminescence (PL) spectra of NLC composites as a function of the concentration of TiO2 nanoparticles (NPs) has also been investigated. PL spectra reveal that the PL-quenching increases in nano-nematic composites with increasing the concentration of TiO2 NPs following to the Stern-Volmer quenching equation. The pure NLC exhibits a strong absorption band nearly at 314 nm, attributing to π-π* transitions in the phenyl rings which has been slightly blue-shifted after the addition of TiO2 NPs. This blue shift was to be attributed to the n → π⁎ electronic transitions in the systems. The doping of TiO2 NPs has a promising application to the field of LC devices and displays.

Dual Stimuli-Responsive High-Efficiency Circularly Polarized Luminescence from Light-Emitting Chiral Nematic Liquid Crystals.

Considerable luminescence dissymmetry factor (glum) is vital for application implementation of circularly polarized luminescence (CPL) materials. Moreover, a dual CPL switch has promising prospects in high-security encryption and sensor devices. Herein, we designed and synthesized an emissive chiral nematic liquid crystal (N*-LC) by doping a luminescent chiral additive (NO2-CS-C6-Chol) into a nematic liquid crystal (5CB). The helical assembly structure produced by inducing the formation of N*-LC endows the prepared emissive N*-LC with a larger glum value. With the increase of the doping concentration from 1 to 10 wt %, the helical pitch (P) of N*-LC gradually decreases from 25.48 to 3.92 μm. The corresponding glum value increases first, reaches the maximum value (-0.38) at 6 wt %, and then decreases slightly. Further, the prepared emissive N*-LC doped with 6 wt % NO2-CS-C6-Chol is injected into an indium-tin oxide (ITO)-coated LC cell, to which a direct current (DC) electric field is applied. The glum value can be repeatedly shuttled between the "on" and "off" state by adjusting the applied voltage. Meanwhile, owing to the inherent thermal dependence of the liquid crystal phase structure, the glum value can also be switched between the on and off state by regulating the temperature. Therefore, an electrically controlled and thermocontrolled dual CPL switching device is successfully constructed.