Multi-dimensional multiplexing optical secret sharing framework with cascaded liquid crystal holograms

Secret sharing is a promising technology for information encryption by splitting the secret information into different shares.However,the traditional scheme suffers from information leakage in decryption process since the amount of available information channels is limited.Herein,we propose and demonstrate an optical secret sharing framework based on the multi-dimensional multiplexing liquid crystal(LC)holograms.The LC holograms are used as spatially separated shares to carry secret images.The polarization of the incident light and the distance between different shares are served as secret keys,which can significantly improve the information security and capacity.Besides,the decryption condition is also restricted by the applied external voltage due to the variant diffraction efficiency,which further increases the information security.In implementation,an artificial neural network(ANN)model is developed to carefully design the phase distribution of each LC hologram.With the advantage of high security,high capacity and simple configuration,our optical secret sharing framework has great potentials in optical encryption and dynamic holographic display.

Liquid crystal-integrated metasurfaces for an active photonic platform

Metasurfaces have opened the door to next-generation optical devices due to their ability to dramatically modulate electromagnetic waves at will using periodically arranged nanostructures.However,metasurfaces typically have static optical responses with fixed geometries of nanostructures,which poses challenges for implementing transition to technology by replacing conventional optical components.To solve this problem,liquid crystals(LCs)have been actively employed for designing tunable metasurfaces using their adjustable birefringent in real time.Here,we review recent studies on LCpowered tunable metasurfaces,which are categorized as wavefront tuning and spectral tuning.Compared to numerous reviews on tunable metasurfaces,this review intensively explores recent development of LC-integrated metasurfaces.At the end of this review,we briefly introduce the latest research trends on LC-powered metasurfaces and suggest further directions for improving LCs.We hope that this review will accelerate the development of new and innovative LC-powered devices.

Dielectric anisotropy in liquid crystal mixtures with nematic and smectic phases

The modulation of dielectric anisotropy(△ε)is pivotal for elucidating molecular interactions and directing the alignment of liquid crystals.In this study,we combine liquid crystals with opposing dielectric anisotropies to explore the impact of varying concentrations on their properties.We report the sign-reversal of△εin both the nematic and smectic A phases of these mixed liquid crystals,alongside a dual-frequency behaviour across a broad temperature spectrum.Our research further quantifies the influence of mixture ratios under various temperatures and electric field frequencies.This exploration may pave the way for the discovery of new physical phenomena.

Liquid crystal droplets formation and stabilization during phase transition process

The study of phase transition processes in liquid crystals(LCs)remains challenging.Most thermotropic LCs exhibit a narrow temperature range and a rapid phase transition from the isotropic(ISO)to the nematic(N)phase,which make it difficult to capture and manipulate the phase transition process.In this study,we observed the evolution of small droplets during the ISO–N phase transition in ferroelectric nematic(NF)LC RM734.After doping with metal nanoparticles(NPs),the temperature range of the phase transition broadened,and the droplets formed during the phase transition remained stable,with their diameter increasing linearly with temperature.In addition,droplets doped with NPs can be well controlled by an external electric field.This discovery not only aids in understanding the fundamental mechanisms of LC phase transitions but also provides a simple alternative method for preparing droplets,which is potentially valuable for applications in optoelectronic devices and sensors.

Stability analysis of a liquid crystal elastomer self-oscillator under a linear temperature field

Self-oscillating systems abound in the natural world and offer substantial potential for applications in controllers,micro-motors,medical equipments,and so on.Currently,numerical methods have been widely utilized for obtaining the characteristics of self-oscillation including amplitude and frequency.However,numerical methods are burdened by intricate computations and limited precision,hindering comprehensive investigations into self-oscillating systems.In this paper,the stability of a liquid crystal elastomer fiber self-oscillating system under a linear temperature field is studied,and analytical solutions for the amplitude and frequency are determined.Initially,we establish the governing equations of self-oscillation,elucidate two motion regimes,and reveal the underlying mechanism.Subsequently,we conduct a stability analysis and employ a multi-scale method to obtain the analytical solutions for the amplitude and frequency.The results show agreement between the multi-scale and numerical methods.This research contributes to the examination of diverse self-oscillating systems and advances the theoretical analysis of self-oscillating systems rooted in active materials.

THE EXISTENCE AND UNIQUENESS OF TIME-PERIODIC SOLUTIONS TO THE NON-ISOTHERMAL MODEL FOR COMPRESSIBLE NEMATIC LIQUID CRYSTALS IN A PERIODIC DOMAIN

In this paper,we are concerned with a three-dimensional non-isothermal model for the compressible nematic liquid crystal flows in a periodic domain.Under some smallness and structural assumptions imposed on the time-periodic force,we establish the existence of the time-periodic solutions to the system by using a regularized approximation scheme and the topological degree theory.We also prove a uniqueness result via energy estimates.

ENERGY CONSERVATION FOR THE WEAK SOLUTIONS TO THE 3D COMPRESSIBLE NEMATIC LIQUID CRYSTAL FLOW

In this paper,we establish some regularity conditions on the density and velocity fields to guarantee the energy conservation of the weak solutions for the three-dimensional compressible nematic liquid crystal flow in the periodic domain.

Advances in Liquid Crystal Epoxy:Molecular Structures,Thermal Conductivity,and Promising Applications in Thermal Management

Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large-power,high-frequency,and highvoltage insulating packaging applications,due to the challenge of achieving high thermal conductivity(k),desirable dielectric performance,and robust thermomechanical properties simultaneously.Liquid crystal epoxy(LCE)emerges as a unique epoxy,exhibiting inherently high k achieved through the self-assembly of mesogenic units into ordered structures.This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy,while demonstrating a prominently enhanced k.As such,liquid crystal epoxy materials represent a promising solution for thermal management,with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment.This article provides a comprehensive review on recent advances in liquid crystal epoxy,emphasizing the correlation between liquid crystal epoxy’s microscopic arrangement,organized mesoscopic domain,k,and relevant physical properties.The impacts of LC units and curing agents on the development of ordered structure are discussed,alongside the consequent effects on the k,dielectric,thermal,and other properties.External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated.Finally,potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed.

WEAK-STRONG UNIQUENESS FOR THREE DIMENSIONAL INCOMPRESSIBLE ACTIVE LIQUID CRYSTALS

The hydrodynamics of active liquid crystal models has attracted much attention in recent years due to many applications of these models.In this paper,we study the weak-strong uniqueness for the Leray-Hopf type weak solutions to the incompressible active liquid crystals in R^(3).Our results yield that if there exists a strong solution,then it is unique among the Leray-Hopf type weak solutions associated with the same initial data.

Influence of the Powder on the Properties of the Liquid Crystal Emulsions

The purpose of study was to evaluate the effect of four powder including titanium dioxide,bismuth oxychloride,silica,and kaolin on the properties of the liquid crystal emulsions.The results show that the addition of titanium dioxide and bismuth oxychloride had no obvious effect on the liquid crystal structure.In addition,the addition of Kaolin and silica have an effect on the stability of the liquid crystal structure.Sensory evaluation and Texture analyzer results shown that the addition of titanium dioxide and bismuth oxychloride had no obvious effect on the spreadability of liquid crystal system.The addition of silica and Kaolin was increased the hardness and adhesive of the liquid crystal system.Rheological experiments shown that the kaolin system had lower structural stability.the system with titanium dioxide,bismuth oxychloride,and silica has good stability.This paper provides data support for the application of powders in the formulation of liquid crystal system,which aims to provide a data basis for the preparation and applications of liquid crystal emulsion.

NOVEL POLYMER WIDE VIEWING ANGLE COMPENSATION FILMS FOR LIQUID CRYSTAL DISPLAYS(LCDS)

We report on generating uniaxial negative birefringent compensation films, made of specifically designedpolyimides. These polymers were synthesized via a polycondensation of dianhydride [such as 2, 2' -bis(3, 4-dicarboxyphenyl)hexafluoropropane dianhydride] and 2, 2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. The uniaxial negative birefringent (n_x =n_y > n_z) polyimide substrates are achieved using a solution-casting method in conventional solvents, which exhibit thedesirable optical phase retardation [(n_x - n_z)×d] values from 50 to 400 nm varying with the film thickness. In thesepolyimide films, the long chain rigid molecules adopt intrinsic planar orientaion. In detail, the majority of phenylene-imiderings and phenylenes preferentially adopt nearly planar conformations parallel to the film substrae. In addition, these filmsalso possess high transparency (or transmittance) and little color shift. The unique color dispersion curve indicates that thistype of materials is very suitable for the applications in LCDs due to an excellent mimic for the retardation color dispersioncurve with respect to LC molecules. Significantly low in-plane retardation (< 1 nm) allows this new technology based film toachieve sufficiently high contrast ratio while highly negative retardation dramatically suppresses the gray scale inversion toimprove the viewing angle performance in a variety of new mode LCDs.

Calculating the dielectric anisotropy of nematic liquid crystals:a reinvestigation of the Maier-Meier theory

This paper investigates the average dielectric permittivity （^-ε） in the Maier-Meier theory for calculating the dielectric anisotropy （△ε） of nematic liquid crystals.For the reason that ^-ε of nematics has the same expression as the dielectric permittivity of the isotropic state,the Onsager equation for isotropic dielectric was used to calculate it.The computed ^-ε shows reasonable agreement with the results of the numerical methods used in the literature.Molecular parameters,such as the polarizability and its anisotropy,the dipole moment and its angle with the molecular long axis,were taken from semi-empirical quantum chemistry （MOCPAC/AM1） modeling.The calculated values of △ε according to the Maier-Meier equation are in good agreement with the experimental results for the investigated compounds having different core structures and polar substituents.

STUDIES ON CRITICAL CONCENTRATION OF LIQUID CRYSTALLINE ETHYLCELLULOSE

Critical concentrations of lyotropic liquid crystalline ethylcellulose in more than ten solvents were determined using both Abbe refractometer and polarized microscopy. Critical concentration C-crit of forming Liquid crystal phase decreased with increasing solubility parameter delta of solvent until approaching the delta of polymer. Although the alcohols used as solvents had the same variation rule, the critical concentration values of their solutions were much higher, due to their excessive large hydrogen bond component of delta. The experiments of using mixed solvents which showed good linear relation between C-crit and delta also proved this rule. A technique of Transmission Optical Analysis was first used to estimate the concentration dependence of critical phase transition temperature T-crit of EC, and a T-C phase diagram could be drawn.

Effect of Polymer Network Morphology on the Performance of Polymer Dispersed Liquid Crystal (PDLC) Composite Films

The effects of the morphologies of liquid crystal (LC) droplets left in polymer network on the performance of polymer dispersed liquid crystal composite films were investigated.By adjusting the relative content range of the crosslinking and diluents,the morphologies of polymer network can be changed.Therefore,the properties of PDLC composite films with imparity polymer morphologies were obtained by experiments and the finite element simulation.Results of the experimental and finite element simulation showed that the electro-optical properties of PDLC composite films were inversely proportional to the domain size of the polymer network and the mechanical properties were proportional to the domain size of the polymer network.

Phase Behavior of Liquid Crystals Formed in [C12mim]CI/H2O and [C12mim] Cl/Alcohols Systems

Phase behaviors of different binary systems involving 1-dodecyl-3-methylimidazolium chlo- ride （[C12mim]Cl） and H20, [C12mim]Cl and different alcohols （1-butanol, 1-pentanol, 1- hexanol and 1-octanol） are investigated at 25 ℃. Hexagonal liquid crystal phase （H1） is identified in [C12mim]Cl/H2O system, and lamellar liquid-crystalline （Lα） phase is found in [C12mim]Cl/alcohols systems by using polarized optical microscopy and small-angle X-ray scattering techniques. The formation of such phases is considered as a synergetic result of the solvatophobic force and the hydrogen-bonded network comprising an imidazoliuin ring, chloride ion and water （or alcohols）, which can be confirmed by Fourier transform infrared spectra. It is noticeable that in [C12mim]Cl/1-octanol system, the lattice spacings of lamellar phase increase with increasing C12mimCl concentration, which is opposite to the results of [C12mim]Cl/H2O system. This may result mainly from stronger static repulsion among hydrophilic headgroups of imidazolium salts arranged in the bilayers of lamellar structures. Further measurements by differential scanning calorimetry indicate that the lamellar phase is stable within a wide temperature range above room temperature. However, the lattice spacings decrease with the increase of temperature, which may. be due to the softening of the hydrocarbon chain of [C12mim]Cl molecules. In different alcohols systems, it is found that the lamellar lyotropic liquid crystal structure is easier to be formed when the carbon chain length becomes longer.

Preparation and improved photocatalytic activity of ordered mesoporous TiO_2 by evaporation induced self-assembly technique using liquid crystal as template

Ordered mesoporous TiO2 （OMPT） was prepared by an evaporation induced self-assembly technique using liquid crystal as template. The key factors affecting the methylene blue （MB） oxidation efficiency were investigated, including the initial concentration of MB, pH value and catalyst concentration. The results show that the obtained OMPT has high thermal stability and shows a 2D hexagonal mesostructure with the small particle size and high surface area, which lead to higher degradation efficiency than commercial P25 or nanoparticle TiO2 （NPT） fabricated by sol-gel process. The optimal conditions are 5 mg/L MB, pH 6 and 1.5 g/L OMPT for the fastest rate of MB degradation. Total organic carbon （TOC） analysis indicates complete mineralization of MB in 240 min by OMPT, with rate constant higher than NPT or P25.

Synthesis and Characterization of Side-Chain Liquid Crystalline Polysiloxanes

Side chain liquid crystalline golysiloxanes conta ing biphenyl and benzyl ether mesogen were synthesized by the hydrosilation of poly(methylhydrcsiloxane) with 4-(4-allyloxybenzytoxy)-4'- methoxybiphenyl(M_1),4-(4-allyloxybenzyloxy)-4'-ethoxybiphenyl(M_2),4-(4-allyloxybenzyloxy)-4'- propoxybiphenyl(M_3),4-(4-allyloxybenzyloxy)-4'-butoxybiphenyl(M_4),4-(4-allyloxybenzyloxy)-4'- pentyloxybiphenyl(M_5).The phase behavior of monomeric and polymeric liquid crystals was chararcterized by differential scanning calorimetry and optical polarization microscopy.Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.

Circuit-Level Analysis on Opto-Electronic Characteristics of Ferroelectric Liquid Crystal

We propose an electronic model in Spice, instead of traditional mathematical analysis, for analyzing the performance of ferroelectric liquid crystal （FLC） under various working conditions. Using this equivalent circuit model,it is easy to simulate and analyze the behavior of an FLC layer in three different typical parameters,including temperature, input light wavelength, and the frequency of driving voltage. We conclude that the response velocity drops as the wavelength increases in the range of visible light, and for the parameter of temperature, the velocity reaches its lowest value when the temperature reaches a certain degree,meanwhile,the frequency of driving voltage exerts important effects on the response velocity only when the frequency is beyond a critical value. Excellent agreement is achieved between simulation and experimental results.

HPLC及LC-MS测定榛子中氯吡苯脲和多菌灵残留

本文采用高效液相色谱法(HPLC)和液相色谱-质谱法(LC-MS)对干果榛子中氯吡苯脲和多菌灵残留量进行含量测定.HPLC和LC-MS均使用C18色谱柱,含量测定采取等度洗脱,流动相:甲醇-水(55∶45,体积比);体积流量:1.0 mL·min-1;测定波长:260 nm;柱温:30℃.LC-MS采取电喷雾离子源,梯度洗脱,体积流量:0.6 mL·min-1,柱温:30℃.结果表明,榛子中氯吡苯脲与多菌灵存在残留,氯吡苯脲质量浓度在1.00~10.00μg·mL-1范围内线性关系良好,加样回收率在95.58%~100.58%;多菌灵质量浓度在1.005~15.075μg·mL-1范围内具有良好的线性关系,加样回收率在95.61%~104.39%.实验证明,HPLC与LC-MS相结合的方法具有操作简便、灵敏度高、检出限低等优点,能有效地检测到榛子样品中膨大剂氯吡苯脲及杀菌剂多菌灵的残留,并确定其残留量,线性关系和回收率结果均令人满意.根据被检测的8批样品中氯吡苯脲和多菌灵两项农药残留量推断,作为一般干果食用榛子是安全的.

Self-assembly and UV-curing Property of Polymerized Lyotropic Liquid Crystal Monomer of Sodium 3,4,5-tris（ll-acryloxyundecyloxy）benzoate

A polymerized lyotropic liquid crystal monomer of sodium 3,4,5-tris（11-acryloxyundecyloxy）- benzoate was synthesized by a convenient route starting from 3,4,5-trihydroxybenzoic acid via esterification followed by etherification, acylation and finally neutralization. The chemi- cal structure was confirmed by Fourier transform infrared （FT-IR） and 1H nuclear magnetic resonance spectral analysis. The self-organization behavior of the monomer with deionized water in methanol at room temperature was also demonstrated. The assemblies were char- acterized by polarized optical microscope and X-ray diffraction. The results show that a solution containing 80：20 of the monomer to water was found to be able to self-organize into Lamellar （La） phase and 92：8 with inverted hexagonal （H]I） phase, which was in ac- cordance with the theoretical calculation of critical packing parameter. It suggests that the concentration of the monomer was the key factor to influence assembly structure. Addi- tionally, the acrylate conversion with different photoinitiators and nanostructure retention after polymerization were investigated. The research shows that the acrylate conversion of the monomer with Darocur2959 could reach up to 78% when irradiated by 30 mW/cm2 UV light of 365 nm for 30 min characterized by Real-time FT-IR as well as the sol-gel method. Meanwhile, the La and HII phase nanostructures were both retained after polymerization.