Acoustic Bessel Vortex Beam by Quasi-Three-Dimensional Reflected Metasurfaces.

Vortex beams have a typical characteristic of orbital angular momentum, which provides a new degree of freedom for information processing in remote communication and a form of non-contact manipulation for trapping particles. In acoustics, vortex beams are generally observed on the surface of a metamaterial structure or in a waveguide with a hard boundary owing to the characteristic of easy diffusion in free space. The realization of an acoustic vortex beam with a long-distance propagation in free space still remains a challenge. To overcome this, we report a type of acoustic Bessel vortex (ABV) beam created by a quasi-three-dimensional reflected metasurface in free space based on phase modulation. By using the Bessel and vortex phase profiles, we can realize an ABV beam with the high performances of both Bessel and vortex beams, and its effective propagation distance is larger than 9.2λ in free space. Beyond that, we discuss the bandwidth and topological charge of the ABV beam in detail, and the fractional bandwidth can reach about 0.28. The proposed ABV beam has the advantages of a high-performance vortex, long-distance propagation, and broad bandwidth, which provide a new pathway for designing multifunctional vortex devices with promising applications.

Intravitreal conbercept improves outcome of proliferative diabetic retinopathy through inhibiting inflammation and oxidative stress.

Conbercept is a newly-developed anti-vascular endothelial growth factor (VEGF) drug. This study aimed to evaluate the effects of conbercept on inflammation and oxidative response in proliferative diabetic retinopathy (PDR). Morphology changes in retinal microvasculature of PDR patients were determined by optical coherence tomographic angiography (OCTA). The mice were injected with streptozocin (STZ) for 20 weeks to induced PDR, then the changes in inflammatory factors, oxidative response and histological analysis were examined with Elisa assay, real time-PCR and commercial kits analysis. Conbercept treatment significantly alleviated the retinal pathological changes and significantly reduced intercellular cell adhesion molecule-1 (ICAM-1), macrophage inflammatory protein-1 (MIP-1), IL-1ß, IL-6 and TNF-α protein levels but not prostaglandin E1 (PGE1), prostaglandin E2 (PGE2) and prostaglandin F2a (PGF2a) levels, all of which were remarkably elevated in aqueous fluid of PDR patients compared with non-PDR subjects. Meanwhile the inhibitory effects of conbercept on these inflammatory factors were proved by RT-PCR assays in mice experiments. And the inflammatory signal such as p-IKBα and p-p65 was correspondingly inhibited by conbercept in STZ-treated mice. Conbercept treatment significantly elevated the aqueous glutathione level of PDR patients and inhibited NOX-1, NOX-4 and ph22phox mRNA expressions and ROS production of PDR mice. Ki67 immunofluorescence staining showed that conbercept inhibited endothelial cell proliferation in retina of PDR mice. In conclusion, conbercept significantly inhibited the angiogenesis, inflammation and oxidative response in PDR mice, and these findings further reveals the molecular mechanisms of conbercept in treating PDR.

Observation of a topological nodal surface and its surface-state arcs in an artificial acoustic crystal.

Three-dimensional (3D) gapless topological phases can be classified by the dimensionality of the band degeneracies, including zero-dimensional (0D) nodal points, one-dimensional (1D) nodal lines, and two-dimensional (2D) nodal surfaces. Both nodal points and nodal lines have been realized recently in photonics and acoustics. However, a nodal surface has never been observed in any classical-wave system. Here, we report on the experimental observation of a twofold symmetry-enforced nodal surface in a 3D chiral acoustic crystal. In particular, the demonstrated nodal surface carries a topological charge of 2, constituting the first realization of a higher-dimensional topologically-charged band degeneracy. Using direct acoustic field measurements, we observe the projected nodal surface and its Fermi-arc-like surface states and demonstrate topologically-induced robustness of the surface states against disorders. This discovery of a higher-dimensional topologically-charged band degeneracy paves the way toward further explorations of the physics and applications of new topological semimetal phases.

Dual-Band Fano Resonance of Low-Frequency Sound Based on Artificial Mie Resonances.

It is reported both experimentally and numerically that dual-band acoustic Fano resonances (AFRs) of low-frequency sound are realized by a compound unit array composed of two types of multiple-cavity unit cells with different inner radii. Eigenmode analyses show that two types of monopolar Mie resonance (MMR) modes can be observed below 650 Hz, which arise from the coupling resonance of the overall structure and the Helmholtz resonance of each resonance cavity, respectively. Based on the MMRs with the out-of-phase characteristic induced by the mutual coupling of the two types of unit cells, the dual-band AFRs, in which the quality factor of the AFR II can exceed 600 when the ratio of the inner radii is closed to 1.0, can be observed. More interestingly, the application of the dual-band AFRs in sound encryption communication is further discussed. The proposed multiple-cavity unit cell and its associated dual-band AFRs provide diverse routes to design multiband sound devices with versatile applications, such as filtering, sensing, and communication.

Binary-phase acoustic passive logic gates.

The recent rapid development of acoustic logic devices has opened up the possibilities of sound computing and information processing. However, simultaneous realization of acoustic logic devices with subwavelength size, broad bandwidth and passive structure still poses a great challenge. To overcome it, we propose a subwavelength acoustic logic gate which consists of binary-phase passive unit cells placed into a multi-port waveguide. Based on the phase manipulations of the unit cells, we experimentally and numerically realize three basic logic gates OR, NOT and AND, and a composite logic gate XOR with a uniform threshold of 0.4 Pa based on linear acoustic interferences. More importantly, We also design a composite logic gate XNOR by a four-port waveguide, and composite logic gates NOR and NAND and a logic operation A⊙(B+C) based on two logic gates. We demonstrate a 0.6λ-length, 0.3λ-width, and 0.2-fractional bandwidth acoustic logic gate constructed by passive structures, which may lead to important advances in various applications, such as acoustic computing, acoustic information processing and integrated acoustics.

The anti-inflammatory and anti-oxidative effects of conbercept in treatment of macular edema secondary to retinal vein occlusion.

To investigate the effects of conbercept on inflammatory and oxidative response in macular edema secondary to retinal vein occlusion (RVO-ME). Retinal microvasculature were detected by optical coherence tomographic angiography (OCTA). The inflammation related factors including prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), prostaglandin F2a (PGF2a), intercellular cell adhesion molecule-1 (ICAM-1) and macrophage inflammatory protein-1 (MIP-1) were determined in human and mice with RVO-ME. OCTA images showed that capillary non-perfusion, enlargement of the foveal avascular zone, telangiectatic vessels and some forms of intraretinal edema in RVO-ME and all these were alleviated by conbercept treatment. PGE1, PGE2, PGF2a, ICAM-1 and MIP-1 in aqueous fluid extracted from RVO-ME patients was significantly increased compared with non-RVO subjects, intravitreal injection of conbercept partly reduced ICAM-1 and MIP-1 levels but not PGE1, PGE2 and PGF2a. The glutathione level was reduced in aqueous fluid extracted from RVO-ME patients but was restored after conbercept treatment. The inflammation, angiogenesis and ROS generation was increased in RVO-ME mice, conbercept partly inhibited these effects. Mechanistically, conbercept inhibited vascular endothelial growth factor (VEGF), ICAM-1, MIP-1, NOX-1 and NOX-4 protein expressions, but not PGE1, PGE2 and PGF2a expressions. Conbercept alleviates RVO-ME through inhibiting inflammation, angiogenesis and oxidative responses. These findings further reveals the molecular mechanism of conbercept for treatment of RVO-ME.

Programmable Coding Acoustic Topological Insulator.

Topological acoustics has recently revolutionized fundamental concepts of acoustic propagation, giving rise to strikingly unique acoustic edge modes immune to backscattering. Despite the rapid progress in this field, simultaneous realization of reconfigurability, intelligentization, and automatic control over acoustic propagation paths is posing a great challenge. This challenge is overcome by proposing the concept of a programmable acoustic topological insulator based on two digital elements "0" or "1," which consist of honeycomb-lattice sonic crystals made of cylindrical rods with different diameters. The acoustic propagation paths in the topological insulators can be controlled automatically by programming different coding sequences, which arises from efficient transformation of pseudospin-dependent edge modes on both interfaces of the digital elements. More importantly, a unique unit is experimentally fabricated that has either a "0" or "1" response automatically manipulated by an air cylinder, and design topological insulators with programmable functionality, to realize three digital acoustic devices, such as a single-pole double-throw switch, a single-pole single-throw switch, and a tunable logic gate. The proposed programmable topological insulators may enable future intelligent acoustic devices with exciting reconfigurable and programmable functionalities, which may lead to important advances in various applications, such as integrated acoustics, acoustic security, and information processing.

Modulating Sound with Acoustic Metafiber Bundles.

Acoustic metamaterials and metasurfaces provide great flexibility for manipulating sound waves and promise unprecedented functionality, ranging from transformation acoustics, acoustic cloaking, acoustic imaging to acoustic rerouting. However, the design of artificial structures with both broad bandwidth and multifunctionality remains challenging with traditional design approaches. Here we present a design and realization of a broadband acoustic metafiber bundle. Very different from previously reported acoustic metamaterials and metasurfaces, not only the metafiber structure is simple, flexible and tunable, but also the metafiber bundle has the advantages of broad bandwidth, high transmission, no resonance-induced energy loss and unchangeable output wavefront owing to eigenmodes in the passbands of the metafiber. Besides, it could also achieve arbitrary complex modulations of cylindrical and plane acoustic wavefronts. The metafiber bundles realize the exciting multifunctionality of both acoustic metamaterials and metasurfaces in a broad frequency range, which provides diverse routes to design novel acoustic devices with versatile applications.

Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator.

We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications.