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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]

Background: Pancreatic cancer (PC) is a highly lethal malignancy regarding digestive system, which is the fourth leading factor of cancer-related mortalities in the globe. Prognosis is poor due to diagnosis at advanced disease stage, low rates of surgical resection, and resistance to traditional radiotherapy and chemotherapy. In order to develop novel therapeutic strategies, further elucidation of the molecular mechanisms underlying PC chemoresistance is required. Ribosomal RNA biogenesis has been implicated in tumorigenesis. Small nucleolar RNAs (snoRNAs) is responsible for post-transcriptional modifications of ribosomal RNAs during biogenesis, which have been identified as potential markers of various cancers. Here, we investigate the U3 snoRNA-associated protein RRP9/U3-55 K along with its role in the development of PC and gemcitabine resistance. Methods: qRT-PCR, western blot and immunohistochemical staining assays were employed to detect RRP9 expression in human PC tissue samples and cell lines. RRP9-overexpression and siRNA-RRP9 plasmids were constructed to test the effects of RRP9 overexpression and knockdown on cell viability investigated by MTT assay, colony formation, and apoptosis measured by FACS and western blot assays. Immunoprecipitation and immunofluorescence staining were utilized to demonstrate a relationship between RRP9 and IGF2BP1. A subcutaneous xenograft tumor model was elucidated in BALB/c nude mice to examine the RRP9 role in PC in vivo. Results: Significantly elevated RRP9 expression was observed in PC tissues than normal tissues, which was negatively correlated with patient prognosis. We found that RRP9 promoted gemcitabine resistance in PC in vivo and in vitro. Mechanistically, RRP9 activated AKT signaling pathway through interacting with DNA binding region of IGF2BP1 in PC cells, thereby promoting PC progression, and inducing gemcitabine resistance through a reduction in DNA damage and inhibition of apoptosis. Treatment with a combination of the AKT inhibitor MK-2206 and gemcitabine significantly inhibited tumor proliferation induced by overexpression of RRP9 in vitro and in vivo. Conclusions: Our data reveal that RRP9 has a critical function to induce gemcitabine chemoresistance in PC through the IGF2BP1/AKT signaling pathway activation, which might be a candidate to sensitize PC cells to gemcitabine. -NNMLsihmhHqHA_x8RjJni Video abstract [ABSTRACT FROM AUTHOR]

Background: Pancreatic cancer (PC) is a highly lethal malignancy regarding digestive system, which is the fourth leading factor of cancer-related mortalities in the globe. Prognosis is poor due to diagnosis at advanced disease stage, low rates of surgical resection, and resistance to traditional radiotherapy and chemotherapy. In order to develop novel therapeutic strategies, further elucidation of the molecular mechanisms underlying PC chemoresistance is required. Ribosomal RNA biogenesis has been implicated in tumorigenesis. Small nucleolar RNAs (snoRNAs) is responsible for post-transcriptional modifications of ribosomal RNAs during biogenesis, which have been identified as potential markers of various cancers. Here, we investigate the U3 snoRNA-associated protein RRP9/U3-55 K along with its role in the development of PC and gemcitabine resistance. Methods: qRT-PCR, western blot and immunohistochemical staining assays were employed to detect RRP9 expression in human PC tissue samples and cell lines. RRP9-overexpression and siRNA-RRP9 plasmids were constructed to test the effects of RRP9 overexpression and knockdown on cell viability investigated by MTT assay, colony formation, and apoptosis measured by FACS and western blot assays. Immunoprecipitation and immunofluorescence staining were utilized to demonstrate a relationship between RRP9 and IGF2BP1. A subcutaneous xenograft tumor model was elucidated in BALB/c nude mice to examine the RRP9 role in PC in vivo. Results: Significantly elevated RRP9 expression was observed in PC tissues than normal tissues, which was negatively correlated with patient prognosis. We found that RRP9 promoted gemcitabine resistance in PC in vivo and in vitro. Mechanistically, RRP9 activated AKT signaling pathway through interacting with DNA binding region of IGF2BP1 in PC cells, thereby promoting PC progression, and inducing gemcitabine resistance through a reduction in DNA damage and inhibition of apoptosis. Treatment with a combination of the AKT inhibitor MK-2206 and gemcitabine significantly inhibited tumor proliferation induced by overexpression of RRP9 in vitro and in vivo. Conclusions: Our data reveal that RRP9 has a critical function to induce gemcitabine chemoresistance in PC through the IGF2BP1/AKT signaling pathway activation, which might be a candidate to sensitize PC cells to gemcitabine. -NNMLsihmhHqHA_x8RjJni Video abstract [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]

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]

One-dimensional (1D) photonic crystal coupled microcavity structure containing indefinite metamaterials was investigated. The Wannier-Stark ladder (WSL) can be obtained in both the Bragg ordinary and the well-known omnidirectional band gaps by modulating widths of the cavities. The time-resolved transmission of a short pulse showed the existence of two types of optical Bloch oscillation in such structures. The transmission and the period of the oscillation are found to decrease with the increasing gradient δ. [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]

The polarization controlled optical signal routing has many important applications in photonics such as polarization beam splitter. By using two-dimensional transmission lines with lumped elements, we experimentally demonstrate the selective excitation of guided modes in waveguides composed of two kinds of single-negative metamaterials. A localized, circularly polarized emitter placed near the interface of the two kinds of single-negative metamaterials only couples with one guided mode with a specific propagating direction determined by the polarization handedness of the source. Moreover, this optical spin-orbit locking phenomenon, also called the photonic spin Hall effect, is robust against interface fluctuations, which may be very useful in the manipulation of electromagnetic signals. [ABSTRACT FROM AUTHOR]