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Second-order topological insulators can be characterized by their bulk polarization, which is believed to be intrinsically connected to the center of the Wannier function. In this study, the existence of second-order topological insulators is demonstrated that feature a pair of partially degenerate photonic bands. These arise from the nonsymmorphic glide symmetry in an all-dielectric photonic crystal. The center of the maximally localized Wannier function (MLWF) is consistently located at the origin but is not equivalent with respect to the sum of constituent polarizations. As a result, topological corner modes can be identified by the distinctly hybridized MLWFs that truncate at the sample boundary. Through full-wave numerical simulations paired with microwave experiments, the second-order topology is clearly confirmed and characterized. These topological corner states exhibit notably unique modal symmetries, which are made possible by the inversion of the Wannier bands. These results provide an alternative approach to explore higher-order topological physics with significant potential for applications in integrated and quantum photonics. For entangled bands induced by nonsymmorphic glide symmetry, the scheme by exploring the hybridization pattern of the maximally localized Wannier function, i.e., the Wannier band-resolved polarization components, serves as a finer second-order topological identifications and classifications that captures the observable and distinct corner states that arise from the domain interface. image

In condensed systems, Weyl quasiparticles have a massless nature and exhibit various relativistic chiral phenomena such as Klein tunneling, chiral anomaly, and Fermi arc surface states. However, in photonic systems, Weyl points (WPs) are protected by the D-2d symmetry, often leading to multiple chiral WPs at the same energy level, which makes generating chirality-related effects challenging. To overcome this hinderance, a perturbation that breaks mirror symmetry in the metallic saddle structure was introduced. This perturbation effectively separates the energies of distinct chiral WPs, enabling the experimental measurement of the spectral intensity for each Weyl band and the assessment of chirality imbalance among the WPs. By maintaining time-reversal symmetry, the present study offers an approach for investigating the imbalance in the chirality of pseudo-fermionic fields in photonic materials.

The moving media theory is applied to a photonic confined structure which is a continuous dielectric slab waveguide with the uniaxial anisotropy and without the discrete translational symmetry. The moving effect not only brings about non-reciprocity to the whole photonic band structure in the co-moving and counter-moving directions, but also leads to the topological transition of local degenerate points within the band diagram. We demonstrate through calculation that the type-II Dirac point can be turned into type-I Dirac point when the uniaxial slab is moving over certain speed. Our results provide a new approach to regulate the topology of degeneracy for two-dimensional photonic bands in the continuous translational symmetry condition.

In conventional plasmonic media and plasmonic metamaterials, such as metallic wire mesh, longitudinal mode of electromagnetic wave manifests itself in frequency overlapping transverse modes, which impedes clear observation of longitudinal-mode-specific physical effects. Through interlacing two sets of wire meshes, an ideal band for longitudinal mode is achieved ranging from zero frequency to plasma frequency where transverse modes are completely forbidden. The unique spectral separation of modes facilitates the observation of pure longitudinal mode and related plasmonic effects in bulk medium. We report the first experiment of anomalous optical transmission, induced solely by electromagnetic longitudinal mode resonance, below plasma frequency in the wire mesh medium.

Topological phases of matter connect mathematical principles to real materials, and may shape future electronic and quantum technologies. So far, this discipline has mostly focused on single-gap topology described by topological invariants such as Chern numbers. Here, based on a tunable kagome model, we observe non-Abelian band topology and its transitions in acoustic semimetals, in which the multi-gap Hilbert space plays a key role. In non-Abelian semimetals, the topological charges of band nodes are converted through the braiding of nodes in adjacent gaps, and their behaviour cannot be captured by conventional topological band theory. Using kagome acoustic metamaterials and pump–probe measurements, we demonstrate the emergence of non-Abelian topological nodes, identify their dispersions and observe the induced multi-gap topological edge states. By controlling the geometry of the metamaterials, topological transitions are induced by the creation, annihilation, merging and splitting of band nodes. This reveals the underlying rules for the conversion and transfer of non-Abelian topological charges in multiple bandgaps. The resulting laws that govern the evolution of band nodes in non-Abelian multi-gap systems should inspire studies on multi-band topological semimetals and multi-gap topological out-of-equilibrium systems.

In this Letter, we theoretically propose and experimentally demonstrate a three-dimensional soundproof acoustic cage structure, hereby denoted as an acoustic metacage. The metacage is composed of six acoustic metamaterial slabs with open holes and hidden bypass space coiling tunnels connected to the holes. Band structure analysis reveals a novel physical mechanism to open a low-frequency broad partial band gap via the band folding in other directions, which can also be interpreted by an effective medium with indefinite effective mass density and negative effective modulus. Transmission loss in simulations and in the acoustic impedance tube are administered. Strikingly, we prove that the soundproofing effect of the metacage is robust against the airflow perturbation induced by a fan. Our work paves a road for low-frequency airborne soundproof structures in the presence of ventilation.

Type-II Dirac point degeneracy can be realized at two-dimensional metasurfaces, where a pair of tilted cones is formed in the dispersion relation ${\omega}(k_{x}, k_{y})$ whose equal-frequency contour at the degeneracy frequency presents an X-shaped cross in k-space. Consequently, two group velocities are obtained at the Dirac point, due to the peculiar shape of the spatial dispersion, and point to the different directions with the intersection angle dependent on the cone's geometry. Therefore, a conical-diffraction phenomenon takes place. We observe the conical diffraction through launching into the metasurface a Gaussian-like beam at the Dirac frequency and mapping the propagation of the wave field. Both experimental and simulating results demonstrate the conical diffraction at the type-II Dirac point.

Type-II Dirac point degeneracy can be realized at two-dimensional metasurfaces, where a pair of tilted cones is formed in the dispersion relation ${\omega}(k_{x}, k_{y})$ whose equal-frequency contour at the degeneracy frequency presents an X-shaped cross in k-space. Consequently, two group velocities are obtained at the Dirac point, due to the peculiar shape of the spatial dispersion, and point to the different directions with the intersection angle dependent on the cone's geometry. Therefore, a conical-diffraction phenomenon takes place. We observe the conical diffraction through launching into the metasurface a Gaussian-like beam at the Dirac frequency and mapping the propagation of the wave field. Both experimental and simulating results demonstrate the conical diffraction at the type-II Dirac point.

Type-II Dirac point degeneracy can be realized at two-dimensional metasurfaces, where a pair of tilted cones is formed in the dispersion relation ${\omega}(k_{x}, k_{y})$ whose equal-frequency contour at the degeneracy frequency presents an X-shaped cross in k-space. Consequently, two group velocities are obtained at the Dirac point, due to the peculiar shape of the spatial dispersion, and point to the different directions with the intersection angle dependent on the cone's geometry. Therefore, a conical-diffraction phenomenon takes place. We observe the conical diffraction through launching into the metasurface a Gaussian-like beam at the Dirac frequency and mapping the propagation of the wave field. Both experimental and simulating results demonstrate the conical diffraction at the type-II Dirac point.

Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.

Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.

Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.

Jinan Shi,1 Yin Duan,2 Lei Pan,2 Xiaoxi Zhou3 1Department of Medical Oncology, Zhejiang Hospital, 2Department of Breast Surgery, Zhejiang Provincial Traditional Chinese Medical Hospital, 3Department of Respiratory Medicine, Zhejiang Hospital, Hangzhou, Zhejiang Province, People’s Republic of China Background: Cluster of differentiation 44 (CD44) is an important surface marker of cancer stem cells in a variety of tumors. A number of previous studies have been conducted to investigate the association between CD44 gene rs13347 C>T polymorphism and cancer risk in humans; nevertheless, the results remain controversial. We therefore performed this meta-analysis to confirm the role of this polymorphism in susceptibility to human cancer.Materials and methods: The studies published up to December 2015 were searched in PubMed, Web of Science, and China National Knowledge Infrastructure databases. Twelve eligible case–control studies were identified, involving a total of 6,982 cases and 7,430 controls. Pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated using a fixed or random-effect model to estimate the strength of the association.Results: The results of the overall analyses indicated that CD44 gene rs13347 polymorphism was significantly associated with cancer risk in Asians (CT vs CC: OR =1.35, 95% CI =1.12–1.62; TT vs CC: OR =1.99, 95% CI =1.52–2.60; TT + CT vs CC: OR =1.41, 95% CI =1.16–1.71; and TT vs CC + CT: OR =1.74, 95% CI =1.41–2.14), especially in Chinese population (CT vs CC: OR =1.42, 95% CI =1.16–1.75; TT vs CC: OR =2.13, 95% CI =1.58–2.86; TT + CT vs CC: OR =1.50, 95% CI =1.21–1.87; and TT vs CC + CT: OR =1.80, 95% CI =1.43–2.26). In stratified analyses by cancer types, there was evidence for an association between this polymorphism and nasopharyngeal cancer and breast cancer, respectively.Conclusion: The results of this m