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Biconvex tube is prone to problems such as severe wall thickness reduction or wrinkling in hydroforming due to the big diameter-thickness ratio and large expansion ratio. In this paper, the segmented dies were employed to manufacture the biconvex tube, and the forming performance of the part under different loading paths was simulated by ABAQUS/Explicit software, then the corresponding results were obtained. The influence of loading path–related factors on the formability of the biconvex tube was analyzed by the response surface method. Based on the optimization evaluation criteria, the predicted loading path was determined to be linear loading, and the maximum axial feeding was 13 mm and the maximum internal pressure was 89 MPa.

Projective non-negative matrix factorization (PNMF) as a variant of NMF has received considerable attention. However, the existing PNMF methods can be further improved from two aspects. On the one hand, the square loss function that is intended to measure the reconstruction error is sensitive to noise. On the other hand, it is non-trivial to estimate the intrinsic manifold of the feature space in a principal manner. So current paper is an attempt that has proposed a new method named as robust ensemble manifold projective non-negative matrix factorization (REPNMF) for image representation. Specifically, REPNMF not only assesses the influence of noise by imposing a spare noise matrix for image reconstruction, but it also assumes that the intrinsic manifold exists in a convex hull of certain pre-given manifold candidates. We aim to remove noise from the data and find the optimized combination of candidate manifolds to approximate the intrinsic manifold simultaneously. We develop iterative multiplicative updating rules for the optimization of REPNMF along with its convergence proof. The experimental results on four image datasets verify that REPNMF is superior as compare to other related state-of-the-art methods.

As existing target tracking algorithms are prone to drift under complex environments, the authors propose a tracking algorithm based on superpixel segmentation and visual attention mechanism. The algorithm works on a particle filter framework, by conducting a superpixel segmentation first and then building a model of the visual attention mechanism for saliently mapping. After extracting HOG features of salient regions, the authors compared the HOG feature with the target template at last, in order to locate the target region in the new frame. The proposed algorithm is evaluated on a comprehensive test platform, in which the simulation show that our tracker is more efficacious and more efficient than the previous traditional target tracking algorithms to cope with target drift issue.

It is an effective approach to manipulate the physical properties of graphene by defects produced by ion irradiation. In this work, we first simulate the process of ions bombardment on graphene by molecular dynamics, present the relationship between the probability of defects occurrence and the kinetic energy of incident ions. Whereafter we calculate the thermal conductivity of graphene suffering from ions irradiation by non-equilibrium molecular dynamics simulation. It is found that the thermal conductivity of graphene is remarkably suppressed by ions irradiation due to the generation of defects such as adatoms and vacancies. The underlying influence of irradiation dose and kinetic energy of incident ions on the thermal conductivity of graphene is well interpreted by the probability of defects occurrence. Our findings are helpful for understanding and tuning the thermal conductivity of graphene by defect engineering.

Mitochondria play extremely important roles in supplying energy and maintaining the functions of cells. It is essential to monitor mitochondrial microenvironments that reflect the status of this organelle. In this review, we summarize the major progress in the developments and applications of mitochondrial targetable trackers and probes. The newly emerged immobilizable probes for microenvironments are highlighted, and their values are commented. Generally, cationic dyes with appropriate lipophilicity tend to accumulate in the mitochondria due to charge attraction from the negative potential of inner membranes. Following this rationale, numerous fluorescent MitoTrackers have been developed. These probes provide opportunities to investigate mitochondrial morphology and functions. However, such electrostatic interactions are not always reliable since the mitochondrial potential is highly changeable with mitochondria status. The probes will leave when the mitochondria lose their potential. In other words, conventional mitochondrial probes are not suitable for monitoring unhealthy mitochondria that have abnormal mitochondrial potentials. Kim's, Chen's and our teams proposed, separately, new designs of mitochondrial probes that can be immobilized to mitochondria through covalent bonds and monitor microenvironmental factors, including pH, viscosity, polarity and temperature. We believe that the developing of immobilizable mitochondrial fluorescent probes is valuable for tracking and monitoring mitochondrial status accurately. Therefore, this paper reviews and prospects mitochondria immobilizable fluorescent probes of important microenvironmental factors.

Water splitting is a promising approach for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The search for highly active and cost-effective bifunctional catalysts to reduce the consumption of noble metals is necessary for efficient electrochemical water splitting. Using noble metal quantum dots has drawn increasing attention. Herein, we developed flower-like Pt–αFe2O3 thin film nanosheets on Ni foam (NF) as a highly efficient bifunctional electrocatalyst for overall water splitting in alkaline electrolyte. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the electrocatalyst. The unique design of Pt (111) quantum dot decorated flower-like αFe2O3 (104) thin film nanosheets exhibited a quantum size effect and possessed many active sites. Pt–αFe2O3/NF electrodes which were loaded with a small amount of Pt quantum dots exhibited low overpotentials for the OER (304 mV@50 mA cm−2) and HER (90 mV@10 mA cm−2), and a low voltage of 1.51 V for overall water splitting in 1 M KOH. Moreover, excellent stability was observed. Therefore, the flower-like nanosheet Pt–αFe2O3/NF electrode is a promising bifunctional electrocatalyst with the quantum size effect for overall water splitting in alkaline solution.

Perovskite ferroelectric thin films have attracted much attention for the potential applications in modern microelectronics, micro-electro-mechanical systems, and information storage. Computer simulation is helpful for optimising the process parameters and manufacturing high-performance ferroelectric thin films. Herein the work presents a kinetic Monte Carlo method for simulating the submonolayer growth of homoepitaxial SrTiO3 (STO) thin films, and investigate the effects of substrate temperature, incident kinetic energy of adatoms, and deposition rate on the growth of STO thin films. The results show that with the increase of the substrate temperature, and the incident kinetic energy, or the decrease of the deposition rate, the density of islands decreases, and the bonding ratio increases. This study provides an understanding of submonolayer STO thin films growth at atomic scale.

Asymmetric transmission (AT) devices are fundamental elements for optical computing and information processing. We here propose an AT device consisting of a pair of coupled complementary subwavelength gratings. Different from previous works, asymmetric dielectric environment is employed for unidirectional excitation of surface plasmon polaritons (SPPs) and thus asymmetric optical transmission, and near-field coupling effect inherent in the coupled complementary structure is exploited to enhance forward transmission and AT behavior, and determine operation bandwidth as well. The influence of asymmetric dielectric environment, effect of vertical and lateral couplings, interactions of electric- and magnetic-dipole moments and the realization of Kerker conditions, are investigated in depth to unearth the AT mechanism and performance. High-performance AT with large forward transmittance of 0.96 and broad bandwidth of 174 nm is achieved at wavelength 1250 nm. Our work helps people to gain a better understanding of near-filed coupling effect in coupled complementary structures, expand their application fields, and it also offers an alternate way to high-performance AT devices.

In recent years, deploying and running data-intensive workflows in cloud platform has become more and more popular in many areas. Unlike computation-intensive applications, a data-intensive workflow typically requires to deal with bulk data transferring between different resource sites, which means some traditional energy-efficiency optimization technologies are difficult to be enforced when running data-intensive workflows. In this paper, we first formulate the power model of a data-intensive workflow, which takes into account power consumption caused by data transferring. Based on this power model, we introduce a novel metric called Shortest Path in terms of Energy Consumption and design an energy-efficient heuristic scheduling algorithm, which is aiming at reducing the extra energy consumption caused by delays of bulk data transferring. Extensive experiments and performance evaluations show that the proposed scheduling algorithm can significantly reduce the overall energy consumption of running data-intensive workflows comparing with several existing algorithms. In addition, the proposed algorithm also exhibits better adaptiveness and robustness when a cloud system is facing intensive and unpredicted workloads.

In order to study the deformation of a textured surface in soft elastohydrodynamic lubrication (EHL) contacts, observation of the deformed surface around the dimple was realized and conducted under a sliding condition with various loads by using optical interferometry. The results show that uneven deformation emerges around the dimple. Both the applied load and sliding velocity have significant influence on the deformation of the soft surface, especially on the deformation pattern. Contrary to the usual assumption, the effect of shear strains in the soft slider on the total surface deformation is increasingly noticeable, and it results in unexpectedly deformation patterns around the dimple.

Dynamical manipulation of plasmon-induced transparency (PIT) in metamaterials promises numerous potential applications; however, previously reported approaches require complex metamaterial structures or an external stimulus, and dynamic control is limited to a single PIT transparency window. We propose here a metamaterial with a simple structure to realize a dynamically controllable PIT effect. Simply by changing the polarization direction of incident light, the number of PIT transparency windows can be increased from 1 to 2, accompanied by a tunable amplitude and a switchable resonance-wavelength. Moreover, a coupled three-level plasmonic system is employed to explain the underlying mechanism and near-field coupling between the horizontal and vertical gold bars, and the analytical results show good consistency with the numerical calculations. This work provides a simple approach for designing compact and tunable PIT devices and has potential applications in selective filtering, plasmonic switching and optical sensing.

In this study, a single-chamber bio-photoelectrochemical system (BPES), integrating advantages of bioelectrochemical system and photocatalysis process, is developed using a g-C 3 N 4 /BiOBr heterojunction photocathode for methyl orange (MO) degradation and simultaneous energy recovery. Photocatalytic activities of g-C 3 N 4 /BiOBr, g-C 3 N 4 and BiOBr are characterized by UV-vis diffuse reflectance spectra (UV-vis DRS) and Photoluminescence (PL) spectra; and electrochemical activities of photocathodes are examined by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Results show that with an applied voltage of 0.8 V and under simulated solar irradiation, MO decolorization with g-C 3 N 4 /BiOBr photocathode reaches 97.8% within 4 h, higher than those with g-C 3 N 4 (85.3%) and BiOBr (87.3%) photocathodes. Likewise, higher hydrogen production rate (143.8 L m −3 d −1 ) is observed using g-C 3 N 4 /BiOBr photocathode; while values for g-C 3 N 4 and BiOBr photocathodes are 124.3 L m −3 d −1 and 117.1 L m −3 d −1 , respectively. PL and EIS reveal that superior performance of g-C 3 N 4 /BiOBr photocathode can be attributed to more efficient separation of photogenerated electron-hole pairs, lower resistance and better charge transfer. Synergistic effect occurs among biological, electrochemical and photocatalytic processes in illuminated BPES for MO removal. Photocathode optimization and system stability evaluation are conducted. This study demonstrates that the BPES holds great potential for efficient refractory organics degradation and energy production.

In order to improve the working stability of distributed marine green energy resources grid-connected system, we need the big data information mining and fusion processing of grid-connected system and the information integration and recognition of distributed marine green energy grid-connected system based on big data analysis method, and improve the output performance of energy grid-connected system. This paper proposed a big data analysis method of distributed marine green energy resources grid-connected system based on closed-loop information fusion and auto correlation characteristic information mining. This method realized the big data closed-loop operation and maintenance management of grid-connected system, and built the big data information collection model of marine green energy resources grid-connected system, and reconstructs the feature space of the collected big data, and constructed the characteristic equation of fuzzy data closed-loop operation and maintenance management in convex spaces, and used the adaptive feature fusion method to achieve the auto correlation characteristics mining of big data operation and maintenance information, and improved the ability of information scheduling and information mining of distributed marine green energy resources grid-connected system. Simulation results show that using this method for the big data analysis of distributed marine green energy resources grid-connected system and using the multidimensional analysis technology of big data can improve the ability of information scheduling and information mining of distributed marine green energy resources grid-connected system, realizing the information optimization scheduling of grid-connected system. The output performance of grid connected system has been improved.

Novel polysaccharide-platinum conjugated polymers bearing alendronate on Portulaca oleracea polysaccharides (PPS) were designed and synthesized. Their chemical structures and properties were characterized by Fourier transform infrared spectroscopy (FT-IR), 1H NMR and 31P NMR spectroscopy, Thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), UV-vis spectrophotometer (UV-vis) and other analysis methods. The results demonstrated that alendronate can be used as the linker of Portulaca oleracea polysaccharides and platinum compounds. Portulaca oleracea polysaccharides-alendronate (PPS-ALN) conjugates exhibited stronger antioxidant ability than PPS. The cytotoxicity assay to cancer cells was tested in vitro, and the Portulaca oleracea polysaccharides-alendronate-platinum (PPS-ALN-Pt) conjugates strongly inhibited the proliferation of cancer cells than PPS and PPS-ALN. The evaluation of complexes affinity toward supercoiled plasmid DNA, displayed a high DNA interaction. Interestingly, the platinum conjugates displayed immunological competence in HeLa cells by cellular immunofluorescence assay. Besides, the cellular platinum accumulation of PPS-ALN-Pt conjugates was higher than that of cisplatin in HeLa cells, implying that the polysaccharide-platinum conjugated polymers might have a synergistically therapeutic application in metal anticancer drug delivery.

The analogue of electromagnetically induced transparency (EIT-like) and electromagnetically induced reflectance (EIR-like) effects have been intensively studied and achieved by using metasurfaces. Nevertheless, previous designs could realize only one of them and were unable to support both effects in a metasurface. Here we numerically and experimentally demonstrate a metasurface simultaneously exhibiting EIT-like and EIR-like effects. Qualitative analyses and quantitative calculations based on the electromagnetic multipole decomposition method are performed to reveal their formation mechanisms. Our work offers a simple avenue for simultaneously realizing EIT-like and EIR-like effects in a metasurface, which may find potential applications in sensing, filtering, and slow wave devices.

Optimal input design for parameter estimation has obtained extensive coverage in the past. A key problem here is that the optimal input depends on some unknown system parameters that are to be identified. Adaptive design is one of the fundamental routes to handle this problem. Although there exist a rich collection of results on this problem, there are few results that address dynamical systems. This paper presents sufficient conditions for convergence/consistency and asymptotic optimality for a class of adaptive systems consisting of a recursive prediction error estimator and an input generator depending on the time-varying parameter estimates. The results apply to a general family of single input single output linear time-invariant systems. An important application is adaptive input design for which the results imply that, asymptotically in the sample size, the adaptive scheme recovers the same accuracy as the off-line prediction error method that uses data from an experiment where perfect knowledge of the system has been used to design an optimal input spectrum.

A two-dimensional elastohydrodynamic numerical simulation is conducted for surface textured sliding bearings with relatively soft material. The pressure distribution in the film and the elastic deformation of the textured surfaces are obtained through a simultaneous solution of the two-dimensional Reynolds equation and the equation of the elasticity for the textured surface. The results show that the small elastic deformation has significant influence on the load carrying capacity and pressure distribution, and leads to a drastic decrease in load capacity at thin film hydrodynamic lubrication. A parametric analysis is conducted to obtain the optimal surface texture parameters in term of load carrying capacity.

The electrode with high catalytic activity, low hydrogen overpotential and low cost is desired for hydrogen evolution reaction (HER) via electrocatalytic water splitting. In this study, Pt/Fe-Ni foam (Pt/Fe-NF) electrode was synthesized via cathodic electrodeposition followed by impregnation deposition. Physical and electrochemical properties of Pt/Fe-NF, NF and Pt/NF electrodes were characterized by various techniques. The Pt/Fe-NF electrode exhibited better electrochemical activity for HER under alkaline condition than those of Pt/NF and NF electrodes, owing to the introduction of zero valences Pt and Fe onto the NF, and synergetic effect resulted from the formation of Fe-Ni alloy. Furthermore, Pt/Fe-NF electrode showed extremely high double-layer capacitance (69.1 mFcm−2), suggesting high active sites for the Pt/Fe-NF. Tafel slope of Pt/Fe-NF was 59.9 mV dec−1, indicating that the Volmer-Heyrovsky HER mechanism was the rate-limiting step. The Pt/Fe-NF electrode with great electrocatalytic activity is a promising electro-catalyst for industrial hydrogen production from alkaline electrolyte.

Monolayer KCuTe is a new-type of two-dimensional (2D) semiconductor material with high carrier mobility and large power energy conversion efficiencies, suggesting its potential application in thermoelectric (TE) and photoelectric fields. Based on the density functional theory (DFT) and semiclassical Boltzmann transport equation, the electronic and phonon transport properties of monolayer KCuTe are systematically studied. Our results show that it possesses an ultralow lattice thermal conductivity value of nearly ∼0.13 W m−1 K−1 at 300 K, mainly attributed to its small phonon group velocity, large Gruneisen parameters, and strong phonon–phonon scattering. Furthermore, the intralayer opposite phonon vibrations greatly restrict the heat transport. Monolayer KCuTe shows an ideal direct band gap of ∼1.21 eV, and a high twofold degeneracy appearing at the Γ point gives a high Seebeck coefficient of ∼2070 μV K−1, leading to high TE performance. Using the transport coefficients together with constant electron relaxation time, the figure of merit (ZT) can reach 2.71 at 700 K for the p-type doping, which is comparable to the well-known TE material SnSe (2.6 ± 0.3 at 935 K). Our theoretical studies may provide perspectives to TE applications of monolayer KCuTe and stimulate further experimental synthesis.

A narrow-band and high-contrast asymmetric transmission (AT) device based on metal-metal-metal (M-M-M) asymmetric grating structure is proposed and investigated. Significantly distinct from previous reports, the upper and lower metallic silver (Ag) gratings are connected by a very thin metallic Ag film, without any dielectric spacer layer or subwavelength slit. Under forward incidence, the M-M-M structure supports efficient surface plasmon polaritons (SPPs) excitation and tunneling, more importantly, it promotes direct and thus high-efficiency SPPs decoupling, enabling high forward transmittance. While under backward incidence, the M-M-M structure offers not only high reflection by the Ag film but also a strong near-field coupling effect between the upper and lower gratings, which further suppresses backward transmittance, leading to near-zero backward transmittance. In addition, the M-M-M structure is optimized for narrow-band operation by employing grating groove depth effect and multiple interference effect. Numerical simulation results demonstrate that high-performance AT with high-quality factor (Q≈91), narrow-bandwidth (6.7 nm) and high contrast ratio is achieved, with forward transmittance of 0.72 and backward transmittance of 0.0015 at visible light (610 nm). Our work provides an alternative and simple way to high-performance AT devices.

Among various tunable optical devices, tunable metamaterials have exhibited their excellent ability to dynamically manipulate lights in an efficient manner. However, for unchangeable optical properties of metals, electromagnetic resonances of popular metallic metamaterials are usually tuned indirectly by varying the properties or structures of substrates around the resonant unit cells, and the tuning of metallic metamaterials has significantly low efficiency. In this paper, a direct-tuning method for semiconductor metamaterials is proposed. The resonance strength and resonance frequencies of the metamaterials can be significantly tuned by controlling free carriers’ distributions in unit cells under an applied voltage. This direct-tuning method has been verified in both two-dimensional and three-dimensional semiconductor metamaterials. In principle, the method allows for simplifying the structure of tunable metamaterials and opens the path to applications in ultrathin, linearly-tunable, and on-chip integrated optical components (e.g., tunable ultrathin lenses, nanoscale spatial light modulators and optical cavities with resonance modes switchable).

Tricyclazole is widely used in agriculture as a pesticide, but its toxicity in vertebrates is currently poorly evaluated. In this study, we used zebrafish to assess the toxicity of tricyclazole. We found that tricyclazole induces liver damage, or hepatotoxicity, in zebrafish, during both development and adulthood. In embryos, we found that tricyclazole affected the liver development rather than other endodermal tissues such as gut and pancreas. In both embryos and adult zebrafish livers, tricyclazole disrupted the relationship between oxidant and antioxidant system and resulted in reactive oxygen species (ROS) overload. Meanwhile, it triggered hepatocyte apoptosis and disturbed carbohydrate/lipid metabolism and energy demand systems. These results suggested that tricyclazole could cause severe consequences for vertebrate hepatic development and function.

Metasurfaces with multiple transparent windows are highly desired and epsilon-near-zero (ENZ) materials offer a good platform for different coupling effects. We propose a hybrid metasurface composed of an indium tin oxide (ITO) nanolayer and a plasmonic metasurface. This device can support two kinds of different coupling effects to achieve double transparent windows in communication band. ITO behaves as an ENZ material and can support an ENZ mode when the real permittivity crosses zero (occurring at about 1.55 μm). In addition to electromagnetic induced transparency (EIT) at 1.31 μm supported by the plasmonic metasurface, another transparent window at 1.55 μm is produced by strongly coupling between the ENZ mode and the plasmonic metasurface. Our works provide a simple way to micro-nano device for multi-transparent windows, and may find applications in filters and sensors.

Compact and planar optical beam splitters are highly desirable in various optical and photonic applications. Here, we investigate two kinds of optical beam splitters by using oligomer-based metasurfaces, one is trimer-based metasurface for 3-dB beam splitting, and the other is pentamer-based metasurface for 1:4 beam splitting. Through electromagnetic multipole decomposition and in-depth mechanism analyses, we reveal that the electromagnetic multipolar interactions and the strong near-field coupling between neighboring nanoparticles play critical roles in beam-splitting performance. Our work offers a deeper understanding of electromagnetic coupling effect in oligomer-based metasurfaces, and provides an alternative approach to planar beam splitters.

We design and fabricate a double-layered chiral metamaterial with 4-fold rotational symmetry, which simultaneously exhibits optical rotation and electromagnetically induced transparency (EIT) effects. Using analytical equivalent circuit model and Lorentz's coupled oscillator model, we interpret the physical mechanisms and derive material equations. Importantly, we find that magnetic dipole and electric quadrupole play important roles in optical rotation and keeping the symmetry of the material equations. Our work offers a better understanding of optical rotation in chiral metamaterials, and provides a new and simple approach to combine optical rotation and EIT effects into a single metamaterial.

Thiophanate-methyl (TM) is widely used all over the world and is a typical example of pesticide residues, which can be detected in the soil, and even in vegetables and fruits. However, the molecular mechanisms underlying the hepatotoxicity of TM are not well understood. In this study, we utilized zebrafish to comprehensively evaluate the hepatotoxicity of TM and explore how the molecular mechanisms of hepatotoxicity are induced. The zebrafish larvae were exposed in 6.25, 12.5 and 25 mg/L TM from 72 to 144 hpf, while the adults were exposed in 2, 4 and 6 mg/L TM for 28 days. Here, we found that 12.5 and 25 mg/L TM induces specifically serious hepatotoxicity but not the toxicity of other organs in zebrafish larvae and adults. Moreover, it might triggered hepatotoxicity by activating the caspase-3 through apoptotic pathways and oxidative stress in zebrafish. Subsequently, this resulted in a metabolic imbalance in the zebrafish's liver. In conclusion, our results disclosed the fact that TM may induce severe hepatotoxicity by mediating activation of caspase-3 and oxidative stress in zebrafish.

In this paper, we theoretically and numerically investigate non-chiral all-dielectric metasurfaces for controlling the polarization angle of linearly polarized light at a 1550 nm telecommunication wavelength. In contrast to conventional chiral metasurfaces, where optical activity is a result of a weak response to two circularly polarized components, our polarization rotator employs two silicon antenna in a unit cell as quarter-wave plates to generate left and right circularly polarized light. The polarization orientation of the transmitted linearly polarized light is subsequently decided by the phase retardation between the two opposite circularly polarized light beams. To demonstrate the concept, we modeled a series of metasurfaces, varying the phase differences between the circularly polarized light beams, to generate linearly polarized light with polarization angles ranging from 0° to 90°. We believe that our findings will further expand and promote new applications of metasurfaces.

Financial conditions can reflect the economic development of manufacturing companies in the past, present and future. The analysis of corporate financial conditions can help to provide information and evidence for decision-making. Therefore, the financial analysis method which is helpful to make decision has been widely concerned by scholars. However, the indexes that reflect the financial condition of the company not only may be clear numbers, but also may be non-numerical information which cannot be represented by the exact value. In order to solve the problem that most existing methods didn't take the fuzzy value and the actual value into consideration, the heterogeneous multi criteria decision (MCDM) is applied to analyze the financial condition of the manufacturing enterprises in this paper. The proposed method employs fuzzy theory to improve extant financial index system and considers quantitative and qualitative attributes, which may leads heterogeneous information, such as real numbers, interval numbers and triangular fuzzy numbers. Furthermore the proposed method determines companies ordering by using TOPSIS based on their total financial condition. Moreover, based on the comparison between these companies, different aspects of the financial conditions can be analyzed in detail. Finally, a case study is conducted to verify the proposed method can effectively analyze the financial conditions of manufacturing companies.

We propose two categories of broadband, high-efficiency reflective wave plates operating in the infrared region. The first one is a half-wave plate (HWP) composed of single L-shaped antennas, and the second one is a quarter-wave plate (QWP) composed of double L-shaped antennas. In contrast to the conventional wave plate, the proposed QWP is a simple combination of two HWPs. We theoretically analyze the feasibility of the design and simulate the conversion efficiency. The proposed HWP and QWP are highly efficient with bandwidths of 1670–2791 nm and 1592–3867 nm, respectively. The novel design may be beneficial for the implementation of polarization conversion devices.

This paper reports that the spherical cactus-like composite NiCo2S4@δ-MnO2/NF is an effective overall water-splitting bifunctional electrocatalyst consisting of the excellent electrolyzed water material 1D NiCo2S4 nanowire and 2D layered δ-MnO2. The innovative catalyst not only has the advantages of 1D nanowires and 2D nanosheets, but also forms 1D/2D bonding heterostructures and spherical cactus-like 3D morphology. Under the synergy of heterostructures and 3D morphology, when the electrolyte is alkaline, the overpotential required in the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is low. In addition, when the catalyst is subjected to overall water splitting in a two-electrode system of an alkaline electrolyte, it can also obtain a desired current density at a low overpotential. Moreover, when the material is used in electrolytes with different alkalinity, it demonstrates excellent stability under different electrolytes. A good industrial application prospects can be expected for the transition metal electrocatalyst.

It is highly desirable to develop asymmetric transmission (AT) devices for both linearly and circularly polarized light. However, currently existing metamaterial-based AT devices require multi-step micro-nano fabrication processes and usually realize AT responses only for linearly or circularly polarized waves, not simultaneously for both. We here propose a dual-band AT device for both linearly and circularly polarized waves in the near-infrared region by using a bilayer coupled complementary chiral metasurface, which includes a half-gammadion-shape gold (Au) structural layer and its Babinet's complimentary copy. Unlike other multilayer AT devices working at optical frequencies, it takes less micro-nano fabrication steps. Besides, with the help of chirality and the inherent near-field coupling effect between the two complementary Au layers, the maximal AT parameters for linearly and circularly polarized waves can reach up to 0.45 and 0.56, respectively. The underlying mechanisms of dual-band AT responses are also investigated in depth from the perspectives of chirality and coupling effect. Our work offers a new and simple approach to high-performance AT devices, helps to better understand near-filed coupling effect in coupled complementary metasurfaces, and also expands their application fields.

Realizing versatile functionalities in a single photonic device is crucial for photonic integration. We here propose a polarization-switchable and wavelength-controllable multi-functional metasurface. By changing the polarization state of incident light, its functionality can be switched between the flat focusing lens and exciting surface-plasmon-polariton (SPP) wave. Interestingly, by tuning the wavelength of incident light, the generated SPP waves can also be controlled at desired interfaces, traveling along the upper or lower interface of the metasurface, or along both of them, depending on whether the incident light satisfies the first or second Kerker condition. This polarization-switchable and wavelength-controllable multifunctional metasurface may provide flexibility in designing tunable or multifunctional metasurfaces and may find potential applications in highly integrated photonic systems.

Asymmetric optical transmission is fundamental and highly desirable in information processing and full manipulation of lightwave. We here propose an asymmetric optical transmission device consisting of a gradient metasurface and a one-dimensional subwavelength grating. Owing to the unidirectional excitation of surface plasmon polaritons (SPPs) by the gradient metasurface, and SPP-assisted extraordinary optical transmission, forward incident light has much higher transmission than the backward one. We combine temporal coupled mode theory and finite-difference time-domain simulations to verify its operation principle and study the performance. The results indicate that asymmetric transmission with high-contrast and large forward transmittance can be obtained around the 1.3 µm optical communication band.

Huygens’ meta-atom is the basic building unit of Huygens’ metasurfaces allowing for almost arbitrary wavefront shaping across a surface. We here present a kind of Huygens’ meta-atom by coupling a nanodisk to its Babinet-complementary structure (nanohole), and develop an optical lumped nanocircuit model to analyze vertical and lateral coupling effects and resonance frequencies. Simulation results show that the tuned coupling via lateral misalignment between the two nanostructures is sufficient to shape the wavefront without changing the dimensions or orientations of antennas. By tuning the coupling via lateral misalignment, we design a reflective gradient metasurface based on one coupled mode and a high-efficiency transmissive gradient metasurface working in the spectral overlap of electric and magnetic resonances to realize beam deflection. The proposed coupling-based Huygens’ meta-atom is a new building block for plasmonic metasurfaces with enhanced light-matter interactions, high-efficiency and almost arbitrary wavefront shaping over the full electromagnetic spectrum.

An optical nanocircuit model is proposed to quantitatively and fundamentally understand the coupling mechanism in bilayered self-complementary metamaterial (BSCM) consisting of an array of nanodisks and its complements. Numerical simulations verify the validity of this model in complex structures.

By employing the one-way excitation of surface plasmon polaritons (SPPs), we propose a novel metasurface-based asymmetric electromagnetic wave transmitter with large working bandwidth and high contrast ratio. Temporal coupled mode theory and simulations are used to study its mechanism and performances.

Tetrabromobisphenol A (TBBPA), a toxic persistent pollutant, should be effectively removed from the environment. In this study, an electrochemical sequential reduction-oxidation system was proposed by controlling reaction atmosphere with Pd-Fe nanoparticles modified Ni foam (Pd-Fe/Ni) electrode as cathode for TBBPA degradation. To obtain an efficient Pd-Fe/Ni electrode for TBBPA degradation, various factors, like Pd loading, Fe2+ adding amounts, were examined. The Pd-Fe/Ni electrode exhibited higher TBBPA conversion and debromination than the counterparts, due to the synergism of Fe0 and electrochemical reduction. Similar TBBPA conversions and debromination ratios were observed for the cases of sparging N2 only and sparging N2 followed by air, which were higher than those of aeration. Reductive debromination occurred while first bubbling N2, forming tri-BBPA, di-BBPA, mono-BBPA and BPA; and these intermediates were likely to be further oxidized by OH generated from H2O2 together with Pd-Fe/Ni electrode under aeration. Reductive and oxidative intermediates (including aromatic ring-opened product) were identified by HPLC and UPLC-QTOF-MS. Based on the intermediates, the possible TBBPA degradation mechanism and pathway were proposed. This study demonstrates that sequential reduction-oxidation process tuned by N2 and air bubbling was favored for TBBPA degradation, thus, it should be a promising process for HOCs degradation.

We propose an asymmetric transmission device based on two non-parallel gratings made of Si and Au, which shows wide-angle and high contrast ratio asymmetric transmission over ultra-wide spectral range covering 1.3-1.5 μm optical communication band.

The single-chamber microbial electrolysis cell constructed with a TiO2-coated photocathode, termed photocatalytic microbial electrolysis cell (PMEC), was developed to accelerate methyl orange (MO) degradation and concurrent hydrogen (H2) recovery under UV irradiation. Results showed that faster MO decolorization rates were achieved from the PMEC compared with those without UV irradiation or with open circuit. With increase of MO concentrations (acetate as co-substrate) from 50 to 300mg/L at an applied voltage of 0.8V, decolorization efficiencies decreased from 98% to 76% within 12h, and cyclic H2 production declined from 113 to 68mL. As the possible mechanism of MO degradation, bioelectrochemical reduction, co-metabolism reduction, and photocatalysis were involved; and degradation intermediates (mainly sulfanilic acid and N,N-dimethylaniline) were further degraded by OH generated from photocatalysis. This makes MO mineralization be possible in the single-chamber PMEC. Hence, the PMEC is a promising system for dyeing wastewater treatment and simultaneous H2 production.

Shaping the flow of light based on abrupt phase discontinuities operation in high order modes is investigated. As a proof-of-concept, we design two types of super cells consisting of V-shaped antennas with phase shifts covering 2*2π and 3*2π. The simulations show that the linear gradient phased metasurfaces using the new designed super cells can exhibit exceptional abilities for light-steering functioned as meta-echelette gratings operating in high order diffraction modes. This results could lead to wide applications in photonic research.

In this work, plasmonic metasurfaces with abrupt phase discontinuities operating in high order modes are investigated for manipulating the wavefront of light. We first design two types of meta-super-cells consisting of V-shaped antennas with the phase shift coverage larger than 2π. And then, we create two linear gradient phased metasurfaces using the designed cells, which exhibit exceptional abilities for light-steering functioned as meta-echelette gratings operating in high order diffraction modes, may be valuable for using in high resolution spectrographs and advantage to achieve high numerical aperture plasmonic lenses. Based on the new designed super cells we further build another two azimuthal gradient phased metasurfaces that are able to generate high order optical vortex beams. Our results could lead to wide applications in photonic research.

Asymmetric metal-dielectric nanostructures are demonstrated superior optical properties arising from the combination of strong enhancement of near-fields and controllable scattering characteristics which originate from plasmonic and high-index dielectric components. Here, being inspired by the recent advances of the asymmetric hybrid nanoparticles fabrication [Dmitry Zuev, et al., Adv. Mater. 28, 3087 (2016)], we suggest and study numerically a novel type of hybrid dimer nanoantennas. The nanoantennas consist of asymmetric metal-dielectric (Au/Si) nanoparticles and allow tuning of the near- and far-field properties via laser induced reshaping of the metal part at the nanoscale. We demonstrate an ability to modification of the scattering properties, near-field distribution profilis, normalized local density of states, and radiation patterns of the nanoantenna upon the laser reshaping. The parameters used to investigate these effects correspond to experimentally demonstrated values.

Recursive stochastic algorithms have various applications. In the literature, it is assumed that the true value lies in a connected domain. But, in many cases, it is known that the true value is contained in the union of a finite number of pairwise disjoint sets instead of a connected domain. In these situations, the existing algorithms may be not applicable. To cope with this problem, this paper proposes recursive stochastic algorithms with (event-triggered) Markovian jumps and presents sufficient conditions for almost sure convergence of the proposed algorithms. As an example of applications, this paper significantly improves an existing adaptive algorithm with the proposed method for consistent estimation of non-minimum phase zeros.