Systematic Analysis of the BrHAT Gene Family and Physiological Characteristics of Brassica rapa L. Treated with Histone Acetylase and Deacetylase Inhibitors under Low Temperature.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Surfactant-Assisted Regulation of WS2/Tourmaline Microstructures for Excellent Photocatalytic Performance.

The controllable electrical and optical properties of two-dimensional tungsten disulfide (WS2) attracted much attention in photocatalysis, but commercial development has been severely restricted by their restacking properties. Surfactant-assisted synthesis techniques can be considered as an effective option to break this bottleneck. In this work, the effect of surfactants including sodium dodecylbenzene sulfonate (SDBS), hexadecyltrimethylammonium bromide (CTAB), and polyvinylpyrrolidone (PVP) on the microstructure of WS2/tourmaline composites prepared by coupled hydrothermal and calcination methods was explored. The WS2 nanosheets were uniformly deposited on the tourmaline surface with the assistance of 1.0 mmol/L SDBS. Meanwhile, WS2/Tour-SDBS exhibited the highest rhodamine B (RhB) degradation activity, which was 1.8 and 2.3 times higher than that of photocatalysts prepared with CTAB and PVP under the same conditions, respectively. This study provides a new tactic for the fabrication of high-performance WS2-based composites.

Dynamically changeable terahertz metamaterial absorbers with intelligent switch and high sensitivity and wide and narrow band perfect absorption.

In this work, we theoretically designed a dynamically changeable terahertz metamaterial absorber with intelligent switch and high sensitivity, wide band and narrow band perfect absorption based on the combination of Dirac semimetal (BDS) and vanadium dioxide (VO2). It features two methods for absorption adjustment: altering the Fermi energy level of BDS to modify the resonant frequency of the absorption peaks and utilizing the phase change of VO2 to regulate the absorption rate of the peaks. In addition, its rotational symmetric design ensures strong polarization-insensitivity. The simulation results demonstrate the presence of two narrowband absorption peaks and one mini-broadband absorption peak within the frequency range of 6.0-9.5 THz, all with absorption rates exceeding 90%. We provide an explanation of the absorption mechanism of the device, employing the relative impedance theory and localized surface plasmon resonance to analyze its electric field distribution. We also defined the refractive index sensitivity (S), which is SI = 378 GHz per RIU and SIII = 204 GHz per RIU. Our device possesses high sensitivity and two methods of adjusting absorption modes, which endow it with advantages in the fields of metamaterial absorbers, intelligent switch, and optical sensors.

High confidence plasmonic sensor based on photonic crystal fibers with a U-shaped detection channel.

In order to improve the performance of optical fiber sensing and expand its application, a photonic crystal fiber (PCF) plasmonic sensor with a U-shaped channel based on surface plasmon resonance (SPR) is proposed. We have studied the general influence rules of structural parameters such as the radius of the air hole, the thickness of the gold film and the number of U-shaped channels using COMSOL based on the finite element method. The dispersion curves and loss spectrum of the surface plasmon polariton (SPP) mode and the Y-polarization (Y-pol) mode as well as the distribution of the electric field intensity (normE) under various conditions are studied using the coupled mode theory. The maximum refractive index (RI) sensitivity achieved in the RI range of 1.38-1.43 is 24.1 µm RIU-1, which corresponds to a full width at half maximum (FWHM) of 10.0 nm, a figure of merit (FOM) of 2410 RIU-1 and a resolution of 4.15 × 10-6 RIU. The results show that the proposed sensor combines the SPR effect, which is extremely sensitive to changes in the RI of the surrounding medium and realizes real-time detection of the external environment by analyzing the light signal modulated by the sensor. In addition, the detection range and sensitivity can be extended by adjusting the structural parameters. The proposed sensor has a simple structure with excellent sensing performance, which provides a new idea and implementation method for real-time detection, long-range measurement, complex environment monitoring and highly integrated sensing, and has a strong potential practical value.

Ligand Engineering Enables Efficient Pure Red Tin-Based Perovskite Light-Emitting Diodes.

With increasing ecological and environmental concerns, tin (Sn)-based perovskite light-emitting diodes (PeLEDs) are competitive candidates for future displays because of their environmental friendliness, excellent photoelectric properties, and low-cost solution-processed fabrication. Nonetheless, their electroluminescence (EL) performance still lags behind that of lead (Pb)-based PeLEDs due to the fast crystallization rate of Sn-based perovskite films and undesired oxidation from Sn2+ to Sn4+ , leading to poor film morphology and coverage, as well as high density defects. Here, we propose a ligand engineering strategy to construct high-quality phenethylammonium tin iodide (PEA2 SnI4 ) perovskite films by using L-glutathione reduced (GSH) as surface ligands toward efficient pure red PEA2 SnI4 -based PeLEDs. We show that the hydrogen-bond and coordinate interactions between GSH and PEA2 SnI4 effectively reduce the crystallization rate of the perovskites and suppress the oxidation of Sn2+ and formation of defects. The improved pure red perovskite films not only show excellent uniformity, density, and coverage but also exhibit enhanced optical properties and stability. Finally, state-of-the-art pure red PeLEDs achieve a record external quantum efficiency of 9.32 % in the field of PEA2 SnI4 -based devices. This work demonstrates that ligand engineering represents a feasible route to enhance the EL performance of Sn-based PeLEDs.

Effect of Siderophore DFOB on U(VI) Adsorption to Clay Mineral and Its Subsequent Reduction by an Iron-Reducing Bacterium.

Uranium mining and nuclear fuel production have led to significant U contamination. Past studies have focused on the bioreduction of soluble U(VI) to insoluble U(IV) as a remediation method. However, U(IV) is susceptible to reoxidation and remobilization when conditions change. Here, we demonstrate that a combination of adsorption and bioreduction of U(VI) in the presence of an organic ligand (siderophore desferrioxamine B, DFOB) and the Fe-rich clay mineral nontronite partially alleviated this problem. DFOB greatly facilitated U(VI) adsorption into the interlayer of nontronite as a stable U(VI)-DFOB complex. This complex was likely reduced by bioreduction intermediates such as the Fe(II)-DFOB complex and/or through electron transfer within a ternary Fe(II)-DFOB-U(VI) complex. Bioreduction with DFOB alone resulted in a mobile aqueous U(IV)-DFOB complex, but in the presence of both DFOB and nontronite U(IV) was sequestered into a solid. These results provide novel insights into the mechanisms of U(VI) bioreduction and the stability of U and have important implications for understanding U biogeochemistry in the environment and for developing a sustainable U remediation approach.

Objective Findings on the K-Doped g-C3N4 Photocatalysts: The Presence and Influence of Organic Byproducts on K-Doped g-C3N4 Photocatalysis.

The thermal-condensation method is widely used for the synthesis of K-doped g-C3N4 photocatalysts, but the presence of organic byproducts in the resultant products is often overlooked in previous reports. Here, we demonstrated the universal presence of organic byproducts in K-doped g-C3N4 synthesized by typical thermal condensation of KOH/melamine, KOH/dicyandiamide, or KOH/urea. Taking the K-doped g-C3N4 photocatalysis for the degradation of dimethyl phthalate as an example, the negative influence of the organic byproducts on K-doped g-C3N4 photocatalysis was confirmed. Specifically, the organic byproducts can be gradually dissolved into the photocatalytic system of K-doped g-C3N4 as new and stable pollutants. Based on the solubility investigations on the byproducts in several solvents, hot-water washing was demonstrated to be a relatively effective approach to remove the organic byproducts from K-doped g-C3N4. The formation of organic byproducts during the synthesis of K-doped g-C3N4 could be ascribed to the fact that the presence of K salts in melamine, dicyandiamide, or urea molecules results in their insufficient thermal condensation into expected g-C3N4. The present work provides objective information about the K-doped g-C3N4 photocatalysts and reminds researchers about the influence of the organic byproducts on the applications of the other impurity-doped g-C3N4 photocatalysts.

Direct Blue Light-Induced Autocatalytic Oxidation of o-Phenylenediamine for Highly Sensitive Visual Detection of Triaminotrinitrobenzene.

o-Phenylenediamine (OPD)-based chromogenic reactions are worthy tools for the development of visual colorimetric assays. The chromogenic reactions are usually triggered by various oxidants, which is not easily tunable and incompatible with some analytes. Herein, we report that direct blue light irradiation can induce the autocatalytic oxidation of OPD to generate 2,3-diaminophenazine (oxidized-state OPD, oxOPD). The autocatalytic photo-oxidation reaction mechanism of OPD is mainly ascribed to the resonant energy transfer between ectronically excited oxOPD and dissolved oxygen to form singlet state oxygen with a high oxidation capacity, which accelerates the oxidation of OPD. We demonstrate that under neutral and alkaline environment, the photoinduced autocatalytic oxidation of OPD is able to be further enhanced by triaminotrinitrobenzene (TATB) explosive because of its inhibition effect on the aggregation caused quenching phenomenon of oxOPD. On this basis, a straightforward visual colorimetric assay for TATB with a tunable dynamic range is developed. This assay is capable of detecting TATB explosive concentrations as low as 2.7 nM. Notably, the obvious color change after addition of TATB enables a naked-eye readout with the lowest detectable TATB concentrations of 60 nM.

Chemically modified mesoporous wood: a versatile sensor for visual colorimetric detection of trinitrotoluene in water, air, and soil by smartphone camera.

There is great interest in detection of the level of 2,4,6-trinitrotoluene (TNT) explosive due to its importance in public security and environmental protection fields. The conventional chemical sensors do not simultaneously realize simple, rapid, sensitive, selective, and direct detection of TNT in different medium without sample pretreatment. Here we present a modified wood-based chemical sensor for visual colorimetric detection of TNT in water, air, and soil. The natural wood undergoes a delignified process, which is further functionalized by 3-aminopropyltriethoxysilane (APTES). When TNT solutions are introduced, the wood-based sensor shows a colorimetric transition from light yellow to brown for naked-eye readout because of the generation of Meisenheimer complex between APTES and TNT. The photographs are collected by smartphone camera, and the RGB components are extracted to calculate the adjusted intensity for qualitative detection of TNT. This visual colorimetric sensor for TNT solution displays a linearity in the range of 0.01-5 mM with a limit of detection of 3 µM. In addition, by taking advantage of its inherent mesostructure, the wood-based sensor can be employed for visual detection of TNT vapor as well. Furthermore, it is also able to directly detect TNT in wet soil samples based on capillary action, in which TNT carried by water transports upward along the wood microchannel, triggering the generation of Meisenheimer complex. Graphical Abstract.

Two-Dimensional Layered Zinc Silicate Nanosheets with Excellent Photocatalytic Performance for Organic Pollutant Degradation and CO2 Conversion.

Two-dimensional (2D) photocatalysts are highly attractive for their great potential in environmental remediation and energy conversion. Herein, we report a novel layered zinc silicate (LZS) photocatalyst synthesized by a liquid-phase epitaxial growth route using silica derived from vermiculite, a layered silicate clay mineral, as both the lattice-matched substrate and Si source. The epitaxial growth of LZS is limited in the 2D directions, thus generating the vermiculite-type crystal structure and ultrathin nanosheet morphology with thicknesses of 8-15 nm and a lateral size of about 200 nm. Experimental observations and DFT calculations indicated that LZS has a superior band alignment for the degradation of organic pollutants and reduction of CO2 to CO. The material exhibited efficient photocatalytic performance for 4-chlorophenol (4-CP) degradation and CO2 conversion into CO and is the first example of a claylike 2D photocatalyst with strong photooxidation and photoreduction capabilities.

Boosted Water Oxidation Activity and Kinetics on BiVO4 Photoanodes with Multihigh-Index Crystal Facets.

The crystal facet of the BiVO4 photoanode has potential influence on its charge-transfer and separation properties as well as water oxidation kinetics. In the present work, a BiVO4 polyhedral film with exposed {121}, {132}, {211}, and {251} high-index facets was synthesized by a facile Bi2O3 template-induced method and investigated as a photoanode for water oxidation. In comparison with the normal BiVO4 film with a {121} monohigh-index facet, the BiVO4 film with multihigh-index crystal facets shows higher activity and faster kinetics for photoelectrochemical water oxidation. Specifically, a higher photocurrent density of 1.21 mA/cm2 was achieved on the multihigh-index facet BiVO4 photoanode at 1.23 V versus reversible hydrogen electrode (RHE) in 0.1 M Na2SO4, which is about 200% improved over the normal BiVO4 photoanode (0.61 mA/cm2 at 1.23 V vs RHE). In addition, a negative shift of 300 mV onset potential for water oxidation was observed on the as-prepared BiVO4 photoanode (0.22 V vs RHE) relative to the normal BiVO4 photoanode (0.52 V vs RHE) in 0.1 M Na2SO4. Although the UV-vis absorbance property and water oxidation pathway not be changed, the charge-transfer and separation properties as well as the overall water oxidation kinetics on the multihigh-index facet BiVO4 film were boosted obviously. Theory calculations reveal that the adsorption of H2O molecules on BiVO4{121} and {132} high-index facets is energetically favorable for subsequent dissociation and oxidation relative to that on {010} and {110} low-index facets. Furthermore, the water oxidation limiting step on {121} and {132} high-index facets of BiVO4 is changed to the step of two protons reacting with •O to form •OOH species (•O + H2O(l) + 2H+ + 2e- → •OOH + 3H+ + 3e-), which is different from the limiting step on {010} and {110} low-index facets that corresponds to the dissociation of H2O to •OH (2H2O(l) + • → •OH + H2O(l) + H+ + e-). In addition, the overpotential of water oxidation limiting step on BiVO4{121} and {132} high-index facets is lower than that on {010} and {110} low-index facets.

Enterovirus 71 antagonizes the antiviral activity of host STAT3 and IL-6R with partial dependence on virus-induced miR-124.

Enterovirus 71 (EV71) has caused major outbreaks of hand, foot and mouth disease. EV71 infections increase the production of many host cytokines and pro-inflammatory factors, including interleukin (IL)-6, IL-10 and COX-2. Some of these molecules could stimulate the signal transducer and activator of transcription 3 (STAT3), which plays a key role in regulating host immune responses and several viral diseases. However, the role of STAT3 in EV71 infection remains unknown. This study found that the phosphorylation levels of STAT3 (pY705-STAT3) are closely related to EV71 infection. Further experiments revealed that STAT3 exerts an anti-EV71 activity. However, the antiviral activity of STAT3 is partially antagonized by EV71-induced miR-124, which directly targets STAT3 mRNA. Similarly, IL-6R, the α-subunit of the IL-6 receptor complex, exhibits anti-EV71 activity and is directly targeted by the virus-induced miR-124. These results indicate that EV71 can evade host IL-6R- and STAT3-mediated antiviral activities by EV71-induced miR-124. This suggests that controlling miR-124 and the downstream targets, IL-6R and STAT3, might benefit the antiviral treatment of EV71 infection.

Prediction of signaling pathways involved in enterovirus 71 infection by algorithm analysis based on miRNA profiles and their target genes.

Enterovirus 71 (EV71) causes major outbreaks of hand, foot, and mouth disease. Host factors and signaling pathways exhibit important functions in the EV71 life cycle. We conducted algorithm analysis based on miRNA profiles and their target genes to identify the miRNAs and downstream signaling pathways involved in EV71 infection. The miRNA profiles of human rhabdomyosarcoma cells treated with interferon (IFN-)-α or IFN-γ were compared with those of cells infected with EV71. Genes targeted by differentially expressed miRNAs were identified and assigned to different signaling pathways according to public databases. The results showed that host miRNAs specifically responded to the viral infection and IFN treatment. Some miRNAs, including miR-124 and miR-491-3p, were regulated in opposite manners by the IFNs and EV71. Some signaling pathways regulated by both EV71 infection and IFN treatment were also predicted. These pathways included axon guidance, Wingless/Int1 (Wnt) signaling cascade, platelet-derived growth factor receptor (PDGFR)/PDGF, phosphatidylinositol 3-kinase (PI3K), Jun N-terminal kinase (JNK)/mitogen-activated protein kinase (MAPK), transforming growth factor-beta receptor (TGF-ßR)/TGF-ß, SMAD2/3, insulin/insulin-like growth factor (IGF), bone morphogenetic protein (BMP), CDC42, ERB1, hepatocyte growth factor receptor (c-Met), eukaryotic translation initiation factor 4E (eIF4E), protein kinase A (PKA), and IFN-γ pathways. The identified miRNA and downstream signaling pathways would help to elucidate the interaction between the virus and the host. The genomics method using algorithm analysis also provided a new way to investigate the host factors and signaling pathways critical for viral replication.

Influence of the first wave of COVID-19 on Chinese students' psychology and behavior: a case study approach.

During the first wave of COVID-19, China demonstrated a strong commitment to epidemic prevention and control. This case study focuses on Z University, which adopted closed management when the epidemic was serious, and examines the influence of COVID-19 on students' psychology and behavior through interviews with 10 students. The research reveals that while students perceive closed management during the epidemic as enhancing safety and promoting learning engagement to some extent, the epidemic also has adverse effects on their physical health, psychology, and social life. These impacts included deteriorating physical health, feelings of rebellion and depression regarding college life, alongside concerns and aspirations regarding future job stability. In the discussion, we suggest that higher education institutions can utilize this information to shape policies and procedures, particularly concerning mental health and risk communication, not only during the current pandemic but also in future emergency or disaster scenarios.

MD-DFT Calculations on Dissociative Absorption Configurations of FOX-7 on (001)- and (101)-Oriented Crystalline Parylene Protective Membranes.

Crystalline poly-para-xylylene (parylene) has the potential for use as a protective membrane to delay the nucleation of explosives by separating the explosives and their decomposition products to decrease the explosive sensitivity. Here, molecular dynamics (MD) and density functional theory (DFT) techniques were used to calculate the dissociative adsorption configurations of 1,1-diamino-2,2-dinitroethylene (FOX-7) on (001)- and (101)-oriented crystalline parylene membranes. Based on the results of the calculations, this work demonstrates that the -NO2-π electrostatic interactions are the dominant passivation mechanism of FOX-7 on these oriented surfaces. FOX-7 can dissociatively adsorb on oriented parylene membranes due to the interactions between the LUMO of the toluene (or methyl) groups on parylene and the HOMO of the -NO2 (or -NH2) groups on FOX-7. The formation of a new intermolecular H-bond with the ONO group leads to FOX-7 decomposition via intramolecular C-NO2 bond fission and nitro-to-nitrite rearrangement. The most likely adsorption configurations are described in terms of the decomposition products, surface active groups of parylene, binding behaviors, and N charge transfer. Importantly, the (001)-oriented parylene AF8 membrane is promising for use as a protective membrane to passivate the high-energy -NO2 bonds during the dissociative adsorption of FOX-7. This study offers a new perspective on the development of protective membranes for explosives.

Multilayer stacked ultra-wideband perfect solar absorber and thermal emitter based on SiO2-InAs-TiN nanofilm structure.

In this paper, a broadband solar absorber is constructed and simulated based on the finite difference time domain method (FDTD). The modeled structure of the absorber consists of cyclic stacking of five absorber cells with different periods on refractory metal W, where a single absorber cell is composed of a three-layer SiO2-InAs-TiN square film. Due to the Fabry-Perot resonance and the surface plasmon resonance (SPR), an absorptivity greater than 90% within a bandwidth of 2599.5 nm was achieved for the absorber. Notably, one of these bands, 2001 nm, is a high-efficiency absorption with an absorption rate greater than 99%. The average absorption efficiency reaches 99.31% at an air mass of 1.5 (AM 1.5), and the thermal radiation efficiencies are 97.35% and 97.83% at 1000 K and 1200 K, respectively. At the same time, the structure of the absorber is also polarization-independent, and when the solar incidence angle is increased to 60°, it still achieves an average absorption of 90.83% over the entire wavelength band (280 nm to 3000 nm). The novelty of our work is to provide a design idea based on a unit structure with multiple cycles, which can effectively expand the absorption bandwidth of the absorber in the visible-near-infrared wavelengths. The excellent performances make the structure widely used in the field of solar energy absorption.

Clay minerals/sodium alginate/polyethylene hydrogel adsorbents control the selective adsorption and reduction of uranium: Experimental optimization and Monte Carlo simulation study.

Clay minerals formations are potential geological barrier (host rocks) for the long-rerm storage of uranium tailing in deep geological repositories. However, there are still obstacles to the efficient retardation of uranium because of the competition between negatively charged regions at the clay minerals end face, surface and between layers, as well as low mineralization capacity. Herein, employing a simple method, we used sodium alginate (SA), an inexpensive natural polymer material, polyethylene (PE), and the natural clay minerals montmorillonite (Mt), nontronite (Nt), and beidellite (Bd) to prepare three hydrogel adsorbents, (denoted as Mt/PE-@SA, Nt/PE-@SA, and Bd/PE-@SA), respectively. The application of obtained hydrogel adsorbents further extends to uranium(VI) removal from aqueous. Due to the synergistic action of SA group and PE group, hydrogel adsorbents showed select adsorption and mineralization effect on uranium(VI), among which the maximum uranium(VI) adsorption capacity of Nt/PE-@SA was 133.3 mg·g-1 and Mt/PE-@SA exhibited strong selectivity for uranium(VI) in the presence of coexisting metal ions. Cyclic voltammetry studies indicated the mitigation and immobilization of uranium species onto adsorbents by both reduction and mineralization. Besides, the synergistic adsorption of SA and PE on clay minerals was hypothesized, and the idea was supported by structure optimizations results from Monte Carlo dynamics simulation (MCD). Three obtained hydrogel adsorbents structural model was constructed based on its physicochemical characterization, the low energy adsorption sites and adsorption energies are investigated using MCD simulation. The simulation results show that obtained hydrogel adsorbents have a strong interaction with uranium(VI), which ensures the high adsorption capacity of those materials. Most importantly, this work demonstrates a new strategy for preparing mineral-based hydrogel adsorbents with enough stability and provides a new perspective for uranium(VI) removal in complex environment.

Three peak metamaterial broadband absorbing materials based on ZnSe-Cr-InAs stacked disk arrays.

Metamaterial absorbers show great potential in many scientific and technological applications by virtue of their sub-wavelength and easy-to-adjust structure, with bandwidth as an important standard to measure the performance of the absorbers. In this study, our team designed a new broadband absorber, which consists of an indium arsenide (InAs) disk at the top, a zinc selenide (ZnSe)-chromium (Cr) stacked disk in the middle and a metal film at the bottom. Simulation results show that the absorber has remarkable absorptivity properties in the mid-long infrared band. In a wavelength range of 5.71-16.01 µm, the average absorptivity is higher than 90%. In the band of 5.86-15.49 µm, the absorptivity is higher than 95%. By simulating the electromagnetic field diagram at each resonant frequency, the reason for high broadband absorptivity is obtained. We also constructed Poynting vector diagrams to further elucidate this phenomenon. Next, we analyzed the influence of different materials and structural parameters on absorptivity properties and tested spectral response at different polarization angles and oblique incidence of the light source in the TM and TE modes. When the source is normally incident, the absorber shows polarization insensitivity. When the angle is 40°, absorptivity is still high, indicating that the absorber also possesses angle insensitivity. The broadband absorber proposed by us has good prospects in infrared detection and thermal radiators.

Temperature-tunable terahertz metamaterial device based on VO2 phase transition principle.

Terahertz devices play an irreplaceable role in the development of terahertz technology. However, at present, it is difficult for most natural materials to respond in the terahertz band, making the devices made of them perform poorly. In order to realize the diversity and tunability of device functions, we designed a terahertz metamaterial device composed of the thermally-induced phase change material VO2. The device structure is composed of a Au bottom layer, a SiO2 dielectric layer and a VO2 top layer. Through software simulation, we found that when T = 313 K, the device has complete reflection ability in the whole terahertz band. When T = 342 K, the average absorptivity is above 95% in the ultra-wide band range of 4.71-9.41 THz, and the absorptivity reaches an amazing 0.99999 at 6.31 THz. Thus, the maximum thermal modulation range of the device is 0.001-0.99999. The Bruggeman effective medium theory clarifies the phase transition characteristics of vanadium dioxide. The Drude model establishes the functional relationship between the conductivity of vanadium dioxide and temperature. The basic principle of high absorption was described using the impedance matching theory. We also drew the electric field intensity diagram during the temperature rise of the device to further confirm the reason for the change in the device performance. In addition, the influence of the absence of different structural layers on the absorptivity was simulated, which reflected the role of each layer structure more intuitively. We also explored the influence of the geometric size of the device on the absorptivity, which provided a certain reference value for practical application. In short, we have designed a tunable terahertz device with simple structure, high absorptivity, and wide absorption bandwidth, which can be used in the fields of energy collection, electromagnetic stealth, and modulation.

A novel highly dispersed calcium silicate hydrate nanosheets for efficient high-concentration Cu2+ adsorption.

Currently, the low cost and effective purification toward heavy metal ions in wastewater has garnered global attention. Herein, we used hydrothermal method to prepare highly dispersed calcium silicate hydrate in fluorite tailings. And the stacking thickness of calcium silicate hydrate layered morphology was less than 5 nm. For high concentration Cu2+ purification investigation in wastewater, we found that the equilibrium adsorption capacity reached 797.92 mg/g via the CSH with 3:2 Ca/Si molar ratio, be 1.43-21.8 times than that of reported data. Therein, the metal-metal exchange and deposition are the primary pathways for Cu2+ adsorption, and electrostatic attraction is the secondary pathway. And the relative ∼100 % removal rate of high-concentration Ni2+ and Cr3+ ions were confirmed via CSH prepared from different tailings. This method offers a cost-effective way to utilize tailings for preparing highly efficient adsorbents toward HMIs removal in wastewater.