ABSTRACT
Soft-matter-based photonic crystals like blue-phase liquid crystals (BPLC) have potential applications in wide-ranging photonic and bio-chemical systems. To date, however, there are limitations in the fabrication of large monocrystalline BPLCs. Traditional crystal-growth process involves the transition from a high-temperature disordered phase to an ordered (blue) phase and is generally slow (takes hours) with limited achievable lattice structures, and efforts to improve molecular alignment through post-crystallization field application typically prove ineffective. Here we report a systematic study on the molecular self-assembly dynamics of BPLC starting from a highly ordered phase in which all molecules are unidirectionally aligned by a strong electric field. We have discovered that, near the high-temperature end of the blue phase, if the applied field strength is then switched to an intermediate level or simply turned off, large-area monocrystalline BPLCs of various symmetries (tetragonal, orthorhombic, cubic) can be formed in minutes. Subsequent temperature tuning of the single crystal at a fixed applied field allows access to different lattice parameters and the formation of never-before-seen monoclinic structures. The formed crystals remain stable upon field removal. The diversity of stable monocrystalline BPLCs with widely tunable crystalline symmetries, band structures, and optical dispersions will significantly improve and expand their application potentials.
ABSTRACT
Solution Gated Graphene Field-Effect Transistors (SGGT) are eagerly anticipated as an amplification platform for fabricating advanced ultra-sensitive sensors, allowing significant modulation of the drain current with minimal gate voltage. However, few studies have focused on light-matter interplay gating control for SGGT. Herein, this challenge is addressed by creating an innovative photoelectrochemical solution-gated graphene field-effect transistor (PEC-SGGT) functionalized with enzyme cascade reactions (ECR) for Organophosphorus (OPs) detection. The ECR system, consisting of acetylcholinesterase (AChE) and CuBTC nanomimetic enzymes, selectively recognizes OPs and forms o-phenylenediamine (oPD) oligomers sediment on the PEC electrode, with layer thickness related to the OPs concentration, demonstrating time-integrated amplification. Under light stimulation, the additional photovoltage generated on the PEC gate electrode is influenced by the oPD oligomers sediment layer, creating a differentiated voltage distribution along the gate path. PEC-SGGT, inherently equipped with built-in amplification circuits, sensitively captures gate voltage changes and delivers output with an impressive thousandfold current gain. The seamless integration of these three amplification modes in this advanced sensor allows a good linear range and highly sensitive detection of OPs, with a detection limit as low as 0.05 pm. This work provides a proof-of-concept for the feasibility of light-assisted functionalized gate-controlled PEC-SGGT for small molecule detection.
ABSTRACT
The use of light-assisted cathode is regarded as an effective approach to reduce the overpotential of lithium carbon dioxide (Li - CO2) batteries. However, the inefficient electron-hole separation and the complex discharge-charge reactions hamper the efficiency of CO2 photocatalytic reaction in battery. Herein, a highly reversible force-assisted Li - CO2 battery has been established for the first time by employing a Bi0.5Na0.5TiO3 nanorods piezoelectric cathode. The high-energy electron and holes generated by the piezoelectric cathode with ultrasonic force can effectively enhance the carbon dioxide reduction reaction (CDRR) and carbon dioxide evolution reaction (CDER) kinetics, thereby reducing the overpotentials during the discharge-charge processes. Moreover, the morphology of the discharge product (Li2CO3) can be modified via the dense surface electrons of the piezoelectric cathode, resulting in the promoted decomposition kinetics of Li2CO3 in charging progress. Thus, the force-assisted Li - CO2 battery with the unique piezoelectric cathode can adjust the output and input energy by ultrasonic wave, and provides an ultra-low charging platform of 3.52 V, and exhibits excellent cycle stability (a charging platform of 3.42 V after 100 h cycles). The investigation of the force-assisted process described herein provides significant insights to solve overpotential in the Li - CO2 batteries system.
ABSTRACT
Peptidoglycan recognition proteins (PGRPs) play an important role in innate immunity by recognizing components of pathogenic bacteria (such as peptidoglycan, PGN) and are evolutionarily conserved pattern recognition receptors (PRRs) in both invertebrates and vertebrates. In the present study, two long-type PGRPs (designed as Eco-PGRP-L1 and Eco-PGRP-L2) were identified in orange-spotted grouper (Epinephelus coioides), which is a major economic species cultured in Asia. The predicted protein sequences of both Eco-PGRP-L1 and Eco-PGRP-L2 contain a typical PGRP domain. Eco-PGRP-L1 and Eco-PGRP-L2 exhibited organ/tissue-specific expression patterns. An abundant expression of Eco-PGRP-L1 was observed in pyloric caecum, stomach and gill, whereas a highest expression level of Eco-PGRP-L2 was found in head kidney, spleen, skin and heart. In addition, Eco-PGRP-L1 is distributed in the cytoplasm and nucleus, while Eco-PGRP-L2 is mainly localized in cytoplasm. Both Eco-PGRP-L1 and Eco-PGRP-L2 were induced following the stimulation of PGN and have PGN binding activity. In addition, functional analysis revealed that Eco-PGRP-L1 and Eco-PGRP-L2 possess antibacterial activity against Edwardsiella tarda. These results may contribute to understand the innate immune system of orange-spotted grouper.
Subject(s)
Bass , Animals , Phylogeny , Carrier Proteins/genetics , Amino Acid Sequence , Peptidoglycan/metabolismABSTRACT
Photoassisted electrochemical reaction is regarded as an effective approach to reduce the overpotential of lithium-oxygen (Li-O2 ) batteries. However, the achievement of both broadband absorption and long term battery cycling stability are still a formidable challenge. Herein, an oxygen vacancy-mediated fast kinetics for a photoassisted Li-O2 system is developed with a silver/bismuth molybdate (Ag/Bi2 MoO6 ) hybrid cathode. The cathode can offer both double advantages for light absorption covering UV to visible region and excellent electrochemical activity for O2 . Upon discharging, the photoexcited electrons from Ag nanoplate based on the localized surface plasmon resonance (LSPR) are injected into the oxygen vacancy in Bi2 MoO6 . The fast oxygen reaction kinetics generate the amorphous Li2 O2 , and the discharge plateau is improved to 3.05 V. Upon charging, the photoexcited holes are capable to decompose amorphous Li2 O2 promptly, yielding a very low charge plateau of 3.25 V. A first cycle round-trip efficiency is 93.8% and retention of 70% over 500 h, which is the longest cycle life ever reported in photoassisted Li-O2 batteries. This work offers a general and reliable strategy for boosting the electrochemical kinetics by tailoring the crystalline of Li2 O2 with wide-band light.
ABSTRACT
Linear polarization rotators have been widely used in optical systems. Commonly used polarization rotators are still beset by strong dispersion and thus restricted spectral bandwidth of operation. This leads to the development of achromatic or broadband alternatives, but most of them incorporate multiple waveplates for retardation compensation, which comes at the cost of increased complexity and reduced flexibility in operation and system design. Here, we demonstrate a single-element achromatic polarization rotator based on a thin film of dual-frequency chiral liquid crystal. The angle of polarization rotation is electrically tunable from 0° to 180° with low dispersion (±3°) in the entire visible spectrum, and a high degree of linear polarization (>95%) at the output.
ABSTRACT
In this study, a twisted nematic mode polymer-stabilized liquid crystal (TN mode PSLC) integrated with a crossed polarizer was used to create a transparent waveguide display. When a voltage was applied, the PSLC scattered the waveguide light with a high polarization selectivity such that no substantial loss of the outgoing light intensity was observed after integrating the polarizer. However, with a crossed polarizer, in the ON state, the background light was not only scattered but also absorbed by the analyzer. Using this device configuration, with a 12 µm cell gap and 7% monomer concentration, we successfully realized a normally transparent waveguide display. The contrast ratio of the waveguide outgoing light was 26 and that of the undesired background reached 90. This device can display images due to waveguide edge-lit light scattering and simultaneously block the background information to improve the image quality.
ABSTRACT
This work develops a tunable chirped guided-mode resonant (GMR) filter that has a hybrid splay-twist (HST) liquid crystal as a cladding layer. The GMR filter is a color reflector that strongly reflects light at the resonance wavelength, and its chirped grating structure supports tuning of the resonance peak over a wavelength range of over 50 nm. The HST-LC configuration serves as an achromatic polarization rotator that can rotate the axis of polarization of linearly polarized light by providing effective twist angles in the LC layer under an applied voltage. The HST-LC is used to change the direction of the polarization axis of the light that is reflected by the GMR filter; continuous angles of rotation of â¼90∘ are achieved and the linear polarization is retained under applied voltages. The proposed filter enables an ultrabroadband polarization rotation and still maintains a high degree of linear polarization, which allows more degrees of freedom in spectral and polarization controls.
ABSTRACT
A superhydrophobic surface that has controllable adhesion and is characterized by the lotus and petal effects is a powerful tool for the manipulation of liquid droplets. Such a surface has considerable potential in many domains, such as biomedicine, enhanced Raman scattering, and smart surfaces. There have been many attempts to fabricate superhydrophobic films; however, most of the fabricated films had uniform adhesion over their area. A patterned superhydrophobic surface with spatially controllable adhesion allows for increased functions in the context of droplet manipulation. In this study, we proposed a method based on liquid-crystal/polymer phase separation and local photopolymerization to realize a superhydrophobic surface with spatially varying adhesion. Materials and topographic structures were analyzed to understand their adhesion mechanisms. Two patterned surfaces with varying adhesion were fabricated from a superhydrophobic material to function as droplet guides and droplet collectors. Due to their easy fabrication and high functionality, superhydrophobic surfaces have high potential for being used in the fabrication of smart liquid-droplet-controlling surfaces for practical applications.
ABSTRACT
Dimming and scattering control are two of the major features of smart windows, which provide adjustable sunlight intensity and protect the privacy of people in a building. A hybrid photo- and electrical-controllable smart window that exploits salt and photochromic dichroic dye-doped cholesteric liquid crystal was developed. The photochromic dichroic dye causes a change in transmittance from high to low upon exposure to sunlight. When the light source is removed, the smart window returns from colored to colorless. The salt-doped cholesteric liquid crystal can be bi-stably switched from transparent into the scattering state by a low-frequency voltage pulse and switched back to its transparent state by a high-frequency voltage pulse. In its operating mode, an LC smart window can be passively dimmed by sunlight and the haze can be actively controlled by applying an electrical field to it; it therefore exhibits four optical states-transparent, scattering, dark clear, and dark opaque. Each state is stable in the absence of an applied voltage. This smart window can automatically dim when the sunlight gets stronger, and according to user needs, actively adjust the haze to achieve privacy protection.
ABSTRACT
The polarization dependence of a directional coupler (DC) based on asymmetric cross-slot waveguides is investigated. Due to structural birefringence, the coupling behaviors of the quasi-TE and quasi-TM modes in the DC vary with the waveguide geometry. A polarization-independent directional coupler (PIDC) and polarization beam splitter (PBS) are proposed by tailoring the ratio of the coupling length for quasi-TE and quasi-TM modes. The simulated results show that the coupling lengths of the designed PIDC and PBS are 8 and 28.25 µm, respectively. Both the PIDC and PBS show an insertion loss (IL) <0.7 dB on a bandwidth over 100 nm. The extinction ratios are â¼20 dB for PIDC and â¼14 dB for PBS. The fabrication-error tolerance of the practical devices is also discussed. In this study, we employ a commercial software tool for finite difference eigenmode and three-dimensional finite difference time domain methods to perform the numerical simulations.
ABSTRACT
In this paper, actinomycetes were isolated from vermicompost by tablet coating method. Antimicrobial activities of actinomycetes were measured by the agar block method. Strains with high activity were identified based on morphology and biochemical characteristics, as well as 16S rDNA gene sequence analysis. The results showed that 26 strains of actinomycetes were isolated, 16 of them had antimicrobial activities to the test strains which accounts for 61.54% of all strains. Among the 16 strains, the strain QYF12 and QYF22 had higher antimicrobial activity to Micrococcus luteus, with a formed inhibition zone of 27 mm and 31 mm, respectively. While the strain QYF26 had higher antimicrobial activity to Bacillus subtilis, and the inhibition zone diameter was 21 mm. Based on the identification of strains with high activity, the strain QYF12 was identified as Streptomyces chartreusis, the strain QYF22 was S. ossamyceticus and the strain QYF26 was S. gancidicus. This study provided a theoretical basis for further separate antibacterial product used for biological control.
Subject(s)
Animals , Actinobacteria , Chemistry , Classification , Genetics , Anti-Bacterial Agents , Metabolism , Bacteria , Feces , Microbiology , Molecular Sequence Data , Oligochaeta , Phylogeny , Quality ControlABSTRACT
PZT based multi-system has shown super piezoelectric properties when the composition was located at morphotropic phase boundary (MPB), which divided the regions into rhombohedral and tetragonal structures equally. In the present paper, the diffuse phase transition and phase coexistence of rhombohedral and tetragonal phases of 0.5PZN-0.5PZT ceramics were investigated by Raman scattering spectroscopy in detail. The results revealed that compared with pure PZT, the width of Raman bands of 0.5PZN-0.5PZT was quite broad, indicating that the system has strong relaxor feature. According to the temperature dependence of dielectric permittivity, the indicator of degree of diffuseness, gamma, was calculated and the values were as high as 1.71. Through the separation by Gauss fitting of the Raman bands, the intensities of different Raman vibration modes, such as the tetragonal E (3TO), A1 (3TO), E (4LO) and A1 (3LO) modes, as well as the rhombohedral R1 and Rh modes, were determined. The results indicated that for 0.5PZN-0.5PZT system, the fraction of rhombohedral phase was equal to the tetragonal phase, which has also been affirmed by XRD results and suggested that the system was close to the MPB. Excellentpiezoelectric properties, such as kp (0.66) and d33 (425 pC/N), were found in 0.5PZN-0.5PZT system, showing a great promise of this system as practical materials for piezoelectric actuators.