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In this paper, a dual-polarized Huygens unit is proposed, which has a double-layer metallic pattern etched on both sides of one dielectric substrate. Induced magnetism enables the structure to support Huygens' resonance, thus obtaining nearly complete available transmission phase coverage. By optimizing the structural parameters, a better transmission performance can be achieved. When the Huygens metasurface was used for the design of a meta-lens, good radiation performance was exhibited, with a maximum gain of 31.15 dBi at 28 GHz, an aperture efficiency of 42.7% and a 3 dB gain bandwidth of 26.4 GHz to 30 GHz (12.86%). Due to its excellent radiation performance and very simple fabrication, this Huygens meta-lens has important applications in millimeter-wave communication systems. [ABSTRACT FROM AUTHOR]

Recently, a new type of metasurface, the induced-magnetism Huygens' metasurface, has attracted considerable attention due to its capability to manipulate electromagnetic waves. However, these studies mainly work in a passive way such that the functionalities are fixed once fabricated, limiting the device's adaptability for practical applications and future commercialization. To comply with potential applications, further research endeavors need to be exerted to advance the reconfigurability and practicality. Herein, an ultra-compact and dynamically tunable design strategy of an induced-magnetism Huygens' metasurface is proposed, whose basic unit is a pair of electric dipoles separated by a dielectric spacer and integrated with a varactor in each electric dipole. By simply changing the driven voltage of each unit, the transmission phase can be individually tuned in the near 2 π range; meanwhile, the transmission amplitude remains very high. As a proof-of-concept demonstration, an active magnetism induced Huygens' meta-lens is proposed to exhibit excellent dynamic wavefront manipulation performance. The proposed method may open an avenue toward planar lightweight low-cost dynamic wavefront manipulation devices. [ABSTRACT FROM AUTHOR]

A broadband circularly polarized metasurface antenna with low radar cross section (RCS) is proposed. Four metasurface elements are arranged orthogonally in a 2×2 array and fed with a 90° phase difference to achieve circular polarization radiation. Each metasurface element is a nonuniform subarray of 4×4 metallic patches. Attributed to the nonuniform property of the metasurface element, two characteristic modes with different resonant frequencies but with similar surface current distributions are formed. By optimizing the geometric parameters of the nonuniform element, the two modes are merged with each other, resulting in bandwidth (BW) broadening of the proposed antenna. Simulated and measured results show that the designed antenna has a −10 dB impedance BW of 49.60%, 3 dB axial ratio BW of 33.13%, and peak gain of 13.17 dBic. Moreover, the RCS reduction is higher than 6 dB in the entire operation frequency band. Additionally, the antenna has a low profile of 0.08λ (λ is the free-space wavelength at an operation frequency of 8.25 GHz). [ABSTRACT FROM AUTHOR]

This letter presents a folded reflectarray (FRA) capable of electrical beam steering in the Ka-band. The FRA consists of a low-profile feeding source, a dual-layer wire grid, and 36×36 polarization twisting reflective elements. An element of center shorted patch with two plated through holes is proposed where only two switches are required for polarization twisting and 1-bit encoding. A cavity is then introduced surrounding the element to improve the beam-steering performance. To verify the proposed element, two prototypes with 0° and 60° beam directions are designed and experimented where the metal stub and open circuit are used to model “on/off” states of PIN diodes for simplification. The measured peak gain of 0°FRA is 27.5 dBi with 2 dB gain bandwidth of 28–32 GHz (13.3%). A measured gain drop of 3.25 dB is achieved by the 60°FRA, which verifies the wide-angle beam-steering ability. The measured reflection coefficient of the feeding source is less than −15 dB over the operating band. The proposed FRA has a good potential to realize beam-steering with real PIN diodes for the satellite communications. [ABSTRACT FROM AUTHOR]

Optical nonreciprocal transmission possesses a broad range of applications such as optical isolation, all-optical signal processing, and integrated photonic circuits. The main underlying mechanism is that a static magnetic field can break the time-reversal symmetry in the presence of magneto-optical materials. However, the typical devices usually need a large size because the magneto-optical activity of materials is weak. In this paper, we realize strong nonreciprocal transmission in a one-dimensional photonic crystal with a magnetized epsilon-near-zero defect. The inherent weak magneto-optical activity is significantly enhanced in the magnetized epsilon-near-zero defect because of the field intensity enhancement mechanism. Our results show that the wavelength shift of transmission peaks along two opposite incident directions can be up to 100 times higher than that in the case of a bismuth-iron-garnet defect. These results provide a new perspective to design novel magneto-optical devices with a small size and open novel routes to exploit advanced materials for steering the electromagnetic waves in nano-scale structures. [ABSTRACT FROM AUTHOR]

Background: Upper limb motor dysfunction caused by stroke greatly affects the daily life of patients, significantly reduces their quality of life, and places serious burdens on society. As an emerging rehabilitation training method, brain–computer interface (BCI)–based training can provide closed-loop rehabilitation and is currently being applied to the restoration of upper limb function following stroke. However, because of the differences in the type of experimental clinical research, the quality of the literature varies greatly, and debate around the efficacy of BCI for the rehabilitation of upper limb dysfunction after stroke has continued. Objective: We aimed to provide medical evidence-based support for BCI in the treatment of upper limb dysfunction after stroke by conducting a meta-analysis of relevant clinical studies. Methods: The search terms used to retrieve related articles included "brain-computer interface," "stroke," and "upper extremity." A total of 13 randomized controlled trials involving 258 participants were retrieved from five databases (PubMed, Cochrane Library, Science Direct, MEDLINE, and Web of Science), and RevMan 5.3 was used for data analysis. Results: The total effect size for BCI training on upper limb motor function of post-stroke patients was 0.56 (95% CI: 0.29–0.83). Subgroup analysis indicated that the standard mean differences of BCI training on upper limb motor function of subacute stroke patients and chronic stroke patients were 1.10 (95% CI: 0.20–2.01) and 0.51 (95% CI: 0.09–0.92), respectively (p = 0.24). Conclusion: Brain–computer interface training was shown to be effective in promoting upper limb motor function recovery in post-stroke patients, and the effect size was moderate. [ABSTRACT FROM AUTHOR]

A symbiotic and polymetallic ore containing copper and tin in Yunnan province is complex and the metallic copper and tin, and sulfur were mainly recovered. The oxidation rate of copper has increased and the recovery of copper has become difficult with continuous exploitation of the ore. Therefore, it was unsatisfactory that copper-sulfur flotation separation was carried out to obtain a qualified concentrate. The problems existing in the copper-sulfur flotation system were analyzed in detail according to the practical production. It was proposed to optimize the cyclone selection and operating parameters, to improve equipment configuration and reagent system in bulk roughers, to adjust reagent system in copper-sulfur separation roughers and the amount of grinding medium that were added into tower mill. The Cu grade and recovery in copper concentrate were improved by 3.34 and 3.76 percentage points, respectively. The copper-sulfur flotation system has reached the production standard and achieved good economic benefits for the mine. [ABSTRACT FROM AUTHOR]

A Huygens’ metasurface with unit cells of glide symmetric I-shape metal strips is proposed for a high-efficiency metalens antenna. The proposed unit cell achieves more than 98.6% transmission amplitude with 360° phase shift coverage for dual polarization. The mechanism is presented by analyzing a unit cell with two dislocated I-shape metal strips, where the electric dipole and magnetic dipole resonances are tuned by the dislocation. The analysis implies that glide symmetric I-shape metal strips are preferable for high transmittance Huygens’ unit cell design. With the proposed Huygens’ unit cell, a high-efficiency metalens antenna is realized. The simulated and measured results show that the proposed metalens antenna of a 14-wavelength diameter achieves a maximum gain of 30.7 dBi at 27.2 GHz, which is only 1.1 dB lower than its theoretical limit. The maximum antenna efficiency is 61.5%. The 3-dB bandwidth of achieved gain ranges from 25.9 to 29 GHz, covering the fifth generation (5G) millimeter-wave bands. The proposed metalens remarkably enhances the radiation performance of the metalens antennas. [ABSTRACT FROM AUTHOR]

As a class of transmissive surfaces, Huygens' metasurfaces have attracted much attention in recent years due to their abilities to efficiently manipulate transmitted waves. However, the study of dual‐polarized Huygens' metasurfaces using vialess double‐layer elements has not yet been reported. To overcome this challenge, herein an ultrathin Huygens' metasurface composed of only double‐layer elements without vias is proposed to achieve high transmission and near 360° phase shift for dual polarization. Based on induced magnetism, the top and the bottom elements act as both an electric dipole and a magnetic dipole, inducing the orthogonally electric and magnetic current simultaneously. Then their interaction excites the Huygens' resonance. As an example of an application, a dual‐polarized Huygens' meta‐lens is prepared that exhibits excellent antenna performance. Dual‐polarized Huygens' metasurfaces based on induced magnetism offer extra opportunities for efficient transmitted wave manipulation in metasurfaces. [ABSTRACT FROM AUTHOR]

A double-layered Huygens’ unit cell is proposed to design a broadband metasurface lens (meta-lens) for 5G millimeter-wave antennas. The Huygens’ unit cell consists of a pair of antisymmetric conducting semicircle arc elements on both surfaces of a thin dielectric substrate. The surface currents flowing at the opposite directions on both conducting elements form an electric current loop to induce the orthogonal magnetic current, and then the Huygens’ resonances are stimulated. The Huygens’ unit cell provides the transmission phase coverage of over 400° with transmission amplitude better than −2.3 dB. This breaks through the phase shift limitation of a conventional double-layer frequency-selective surface (FSS) element. It shows that induced magnetism makes such a Huygens-based meta-lens very compact with only one printed circuit board. As an example, a double-layered meta-lens on a 1.5 mm-thick dielectric substrate is designed and experimentally verified. The meta-lens antenna achieves the measured peak gain of 30.7 dBi at 26.2 GHz with an aperture efficiency of 42.25% over the 3 dB bandwidth of 15.7% from 24.1 to 28.2 GHz, fully covering the proposed 5G spectrum from 24.25 to 27.5 GHz. This proposed method greatly helps in the application of promoting planar lightweight low-cost broadband lens antennas in the coming 5G systems. [ABSTRACT FROM AUTHOR]

The nonlinearity and one-way response associated with an electromagnetically induced transparency-like (EIT-like) phenomenon based on a standing wave are theoretically analyzed and experimentally measured. The dark-meta-atom's strong energy localization results in strong second harmonic generation (SHG), while input for the opposite direction elicits no EIT-like response and a 20 dB decrease in SHG strength. The second-order standing wave can be tuned to affect the efficiency of SHG. The results presented here may represent a novel approach to designing nonreciprocal devices such as high signal-to-noise ratio electromagnetic diodes. [ABSTRACT FROM AUTHOR]

Photonic gaps are the core of photonic crystals in the manipulation of light. However, in conventional photonic crystals composed of two types of dielectrics, the photonic gaps strongly depend on the angle of incidence, which limits their applications. In this Letter, we present the experimental demonstration of angle-independent gaps in the visible wavelength range in onedimensional photonic crystals composed of layered hyperbolic metamaterials (HMMs) and dielectrics. HMMs with anomalous wave-vector dispersion can tune the propagating phase of light to an unprecedented extent that usual dielectrics cannot attain. The HMM is mimicked by the layered titanium dioxide and silver with a subwavelength unit cell. Based on the phase-variation compensation effect between the HMM and the dielectric, an angle-independent gap is experimentally realized, which agrees well with the simulated one. This angle-independent gap is very useful in the design of photonic devices such as omnidirectional reflectors with fixed bandwidth or all-angle filters. [ABSTRACT FROM AUTHOR]

In this paper, a shared-aperture transmissive/reflective bi-functional metasurface is proposed. On metasurfaces, antisymmetric dipole pairs as transmissive elements and symmetric dipole pairs as reflective elements are interleaved in orthogonal polarization. By utilizing Huygens' resonance, the metasurface can achieve near full phase coverage for orthogonally polarized transmitted and reflected wave. Then the bi-functional metasurface is used for the design of transmitarray (TA)/reflectarray (RA) bi-functional antenna. The measured results show that, for TA, the maximum gain is 30.26 dBi with antenna efficiency of 45.6 % and the 3-dB gain bandwidth is 26.3–29.3 GHz (10.79 %), and for RA, the maximum gain is 30.29 dBi with antenna efficiency of 45.7 % and the 3-dB gain bandwidth entirely covers the frequency region of 26–30 GHz. The bi-functional metasurface has important applications in the field of antenna engineering. [ABSTRACT FROM AUTHOR]

Optical Tamm states (OTSs) in hetero-structures consisting of highly dispersive planar plasmonic metamaterials and truncated photonic crystal (PC) are investigated numerically. Compared to conventional OTSs in metal-PC structures, the reflectance of tunneling mode can be reduced from -10.2 dB to -32.0 dB, with an optimized Q-factor up to 17 times higher simultaneously. Further study on electromagnetic (EM) field distribution confirms that EM waves are highly localized at some special points. The confinement along the propagating direction provided by OTSs and the in-plane localization originated from the planar plasmonic metamaterials give rise to the three-dimensional enhancement of sub-wavelength EM localization corporately. As the advantages above are not at a cost of extra device volume, this structure is promising to be applied in highly sensitive dielectric sensing, nonlinear optical devices, and so on. [ABSTRACT FROM AUTHOR]

Abstract: We address the dynamics of solitons in the optical lattices with periodic modulation of the nonlinearity coefficient. Based on the quasi-particle approach, the properties of fundamental soliton localized in optical lattices are theoretically analyzed and shown its potential application for controllable soliton switching. Moreover, the phenomena of multi-soliton splitting and the single-soliton constituent trapping in the optical lattices are illustrated and discussed. [Copyright &y& Elsevier]

Ceramide synthases (CerSs) catalyze the formation of ceramides from sphingoid bases and acyl-CoA substrates. Increasing evidence suggests that cancer cells generally exhibit altered sphingolipid metabolism in the tumorigenesis of multiple cancers. However, there is no evidence that CerSs are associated with pancreatic ductal carcinoma (PDAC). In the present study, we examined CerS expression in clinical tissue and conducted data mining to investigate the clinical significance of CerSs in the TCGA-PAAD database. We found that high CerS6 expression positively correlated with progression and predicted worse prognosis in PDAC patients, establishing CerS6 as a potential biomarker for PDAC. Furthermore, CerS6 promoted cell proliferation, colony formation and invasion by producing C16-ceramide and was required for tumor formation. Mechanistically, AKT1 interacted with and phosphorylated FOXP3 at S418, which decreased the binding of FOXP3 to the CERS6 promoter and in turn induced CerS6 expression by reconstituting an activated state on the CERS6 promoter. The AKT1/FOXP3 axis mediated the CerS6 expression and promoted p53 mutant pancreatic tumorigenesis by producing excessive C16-ceramide, which induced the accumulation of mutant p53. Thus, our study explores the relationship between PI3K/AKT signaling and sphingolipid metabolism, revealing an oncogenic role for CerS6, which may represent a potential target for PDAC treatment. [ABSTRACT FROM AUTHOR]

We theoretically study the interface states of liquid surface waves propagating over the heterojunctions formed by a bottom with one-dimensional periodic undulations. By considering the periodic structure as a homogeneous one, our systematic study shows that the signs of the effective depth and gravitational acceleration are opposite within the band gaps whether the structure is symmetric or not. Those effective parameters can be used to predict the interface states which could amplify the amplitudes of liquid surface waves. These phenomena provide new opportunities to control the localization of water-wave energy. • We theoretically studied the propagation of liquid surface waves over a bottom with a one-dimensional periodic undulation. • Our study shows that the signs of the effective depth and gravitational acceleration are opposite within the band gaps. • Those effective parameters can be used to predict the interface states. [ABSTRACT FROM AUTHOR]