Observation of tunable topological polaritons in a cavity waveguide

Topological polaritons characterized by light-matter interactions have become a pivotal platform in exploring new topological phases of matter. Recent theoretical advances unveiled a novel mechanism for tuning topological phases of polaritons by modifying the surrounding photonic environment (light-matter interactions) without altering the lattice structure. Here, by embedding a dimerized chain of microwave helical resonators (electric dipole emitters) in a metallic cavity waveguide, we report the pioneering observation of tunable topological phases of polaritons by varying the cavity width which governs the surrounding photonic environment and the strength of light-matter interactions. Moreover, we experimentally identified a new type of topological phase transition which includes three non-coincident critical points in the parameter space: the closure of the polaritonic bandgap, the transition of the Zak phase, and the hybridization of the topological edge states with the bulk states. These results reveal some remarkable and uncharted properties of topological matter when strongly coupled to light and provide an innovative design principle for tunable topological photonic devices.Comment: 6 pages, 4 figure

Acoustic Three-dimensional Chern Insulators with Arbitrary Chern Vectors

The Chern vector is a vectorial generalization of the scalar Chern number, being able to characterize the topological phase of three-dimensional (3D) Chern insulators. Such a vectorial generalization extends the applicability of Chern-type bulk-boundary correspondence from one-dimensional (1D) edge states to two-dimensional (2D) surface states, whose unique features, such as forming nontrivial torus knots or links in the surface Brillouin zone, have been demonstrated recently in 3D photonic crystals. However, since it is still unclear how to achieve an arbitrary Chern vector, so far the surface-state torus knots or links can emerge, not on the surface of a single crystal as in other 3D topological phases, but only along an internal domain wall between two crystals with perpendicular Chern vectors. Here, we extend the 3D Chern insulator phase to acoustic crystals for sound waves, and propose a scheme to construct an arbitrary Chern vector that allows the emergence of surface-state torus knots or links on the surface of a single crystal. These results provide a complete picture of bulk-boundary correspondence for Chern vectors, and may find use in novel applications in topological acoustics

Observation of Dirac hierarchy in three-dimensional acoustic topological insulators

Dirac cones (DCs) play a pivotal role in various unique phenomena ranging from massless electrons in graphene to robust surface states in topological insulators (TIs). Recent studies have theoretically revealed a full Dirac hierarchy comprising an eightfold bulk DC, a fourfold surface DC, and a twofold hinge DC, associated with a hierarchy of topological phases including first-order to third-order three-dimensional (3D) topological insulators, using the same 3D base lattice. Here, we report the first experimental observation of the Dirac hierarchy in 3D acoustic TIs. Using acoustic measurements, we unambiguously reveal that lifting of multifold DCs in each hierarchy can induce two-dimensional (2D) topological surface states with a fourfold DC in a first-order 3D TI, one-dimensional (1D) topological hinge states with a twofold DC in a second-order 3D TI, and zero-dimensional (0D) topological corner states in a third-order 3D TI. Our work not only expands the fundamental research scope of Dirac physics, but also opens up a new route for multidimensional robust wave manipulation

Prospects of hydrogen as an energy resource

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In Situ Pre-Treatment of Vascularized Composite Allografts With a Targeted Complement Inhibitor Protects Against Brain Death and Ischemia Reperfusion Induced Injuries

Introduction: Donor brain death (BD) is an unavoidable component of vascularized composite allograft (VCA) transplantation and a key contributor to ischemia-reperfusion injury (IRI). Complement is activated and deposited within solid organ grafts as a consequence of BD and has been shown to exacerbate IRI, although the role of BD and complement in VCA and the role it plays in IRI and VCA rejection has not been studied. Methods: BD was induced in Balb/c donors, and the VCA perfused prior to graft procurement with UW solution supplemented with or without CR2-Crry, a C3 convertase complement inhibitor that binds at sites of complement activation, such as that induced on the endothelium by induction of BD. Following perfusion, donor VCAs were cold stored for 6 hours before transplantation into C57BL/6 recipients. Donor VCAs from living donors (LD) were also procured and stored. Analyses included CR2-Crry graft binding, complement activation, toxicity, injury/inflammation, graft gene expression and survival. Results: Compared to LD VCAs, BD donor VCAs had exacerbated IRI and rejected earlier. Following pretransplant in-situ perfusion of the donor graft, CR2-Crry bound within the graft and was retained post-transplantation. CR2-Crry treatment significantly reduced complement deposition, inflammation and IRI as compared to vehicle-treated BD donors. Treatment of BD donor VCAs with CR2-Crry led to an injury profile not dissimilar to that seen in recipients of LD VCAs. Conclusion: Pre-coating a VCA with CR2-Crry in a clinically relevant treatment paradigm provides localized, and therefore minimally immunosuppressive, protection from the complement-mediated effects of BD induced exacerbated IRI

Extra-anatomic revascularization and a new cannulation strategy for preoperative cerebral malperfusion due to severe stenosis or occlusion of supra-aortic branch vessels in acute type A aortic dissection

Objectives: Acute type A aortic dissection (ATAAD) with severe stenosis or occlusion of the true lumen of aortic arch branch vessels often leads to an increased incidence of severe postsurgical neurological complications and mortality rate. In this study, we aimed to introduce our institutional extra-anatomic revascularization and cannulation strategy with improved postoperative outcomes for better management of patients with cerebral malperfusion in the setting of ATAAD. Methods: Twenty-eight patients with ATAAD complicated by severe stenosis or occlusion of the aortic arch branch vessels, as noted on combined computed tomography angiography of the aorta and craniocervical artery, between January 2021 and June 2022 were included in this study. Basic patient characteristics, surgical procedures, hospitalization stays, and early follow-up results were analyzed. Results: The median follow-up duration was 16.5 months (interquartile range: 11.5–20.5), with a 100% completion rate. The 30-day mortality rates was 7.1% (2/28 patients); two patients had multiple cerebral infarctions on preoperative computed tomography and persistent coma. Postoperative transient neurological dysfunction occurred in 10.7% (3/28) of the patients, and no new permanent neurological dysfunction occurred. Of all the patients, 3.6% (1/28) had novel acute renal failure. No other deaths, secondary surgeries, or serious complications occurred during the early follow-up period. Conclusions: Use of extra-anatomic revascularization and a new cannulation strategy before cardiopulmonary bypass is safe and feasible and may reduce the high incidence of postoperative neurological complications in patients with ATAAD and cerebral malperfusion

Observation of multiple rotons and multidirectional roton-like dispersion relations in acoustic metamaterials

Roton dispersion relations were firstly predicted by Landau and have been extensively explored in correlated quantum systems at low temperatures. Recently, the roton-like dispersion relations were theoretically extended to classical acoustics, which, however, have remained elusive in reality. Here, we report the experimental observation of roton-like dispersions in acoustic metamaterials with beyond-nearest-neighbour interactions at ambient temperatures. The resulting metamaterial supports multiple coexisting modes with different wavevectors and group velocities at the same frequency and broadband backward waves, analogous to the ‘return flow’ termed by Feynman in the context of rotons. By increasing the order of long-range interaction, we observe multiple rotons on a single dispersion band, which have never appeared in Landau’s prediction or any other condensed-matter or classical-wave studies. Moreover, we have also theoretically proposed and experimentally observed multidirectional roton-like dispersion relations in a two-dimensional nonlocal acoustic metamaterial. The realization of roton-like dispersions in metamaterials could pave the way to explore novel physics and applications on quantum-inspired phenomena in classical systems.Published versionZ.G. acknowledge support from the National Natural Science Foundation of China under grant number 12104211, 6101020101, SUSTech Start-up Grant (Y01236148, Y01236248). The work at Zhejiang University was sponsored by the Key Research and Development Program of the Ministry of Science and Technology under Grants No. 2022YFA1404902 (Y Y) and No.2022YFA1405201 (Y Y), the National Natural Science Foundation of China (NNSFC) under Grants No. 62175215 (Y Y), the Fundamental Research Funds for the Central Universities (2021FZZX001-19) (Y Y), and the Excellent Young Scientists Fund Program (Overseas) of China (Y Y). H S acknowledged the support of the National Natural Science Foundation of China (Grant Nos. 12274183 and 12174159), and the State Key Laboratory of Acoustics, Chinese Academy of Science under Grant No. SKLA202216

AdS/CFT Correspondence in Hyperbolic Lattices

The AdS/CFT correspondence, also known as the gravity/gauge duality, posits a dual relationship between the theory of gravity in Anti-de Sitter (AdS) space and conformal field theory (CFT) defined on its lower-dimensional boundary. This correspondence provides a means of mapping problems from one theory to the other, offering insights into quantum gravity and quantum field theory. Despite its importance in contemporary physics, the AdS/CFT correspondence remains a conjecture, and further experimental investigation is highly sought after. Here, we experimentally explore the AdS/CFT correspondence in both conventional type-I and previously overlooked type-II hyperbolic lattices, as the discretized regularizations of spatial geometries of pure AdS2+1 spacetime and AdS2+1 black hole. Using time-resolved and pump-prob measurements, we identify distinct geodesic behaviors in the absence or presence of an analogue black hole. Moreover, we experimentally confirm two pivotal theoretical predictions of the AdS/CFT correspondence: the Ryu-Takayanagi (RT) formula that characterizes the entanglement entropy of the boundary CFT2 through the minimal geodesic in the spatial section of bulk AdS2+1, and the exponential dependence of the boundary-boundary two-point correlation function on the hyperbolic distance which determines the conformal dimension of the boundary CFT1 associated with the scalar field mass in the bulk Euclidean AdS2 (EAdS2). This initial experimental effort opens a new avenue for future investigation on the gravity/gauge duality and the exploration of quantum-gravity-inspired phenomena in classical systems

Tetrahydrocurcumin Ameliorates Diabetic Cardiomyopathy by Attenuating High Glucose-Induced Oxidative Stress and Fibrosis via Activating the SIRT1 Pathway

Hyperglycemia-induced oxidative stress and fibrosis play a crucial role in the development of diabetic cardiomyopathy (DCM). Tetrahydrocurcumin (THC), a major bioactive metabolite of natural antioxidant curcumin, is reported to exert even more effective antioxidative and superior antifibrotic properties as well as anti-inflammatory and antidiabetic abilities. This study was designed to investigate the potential protective effects of THC on experimental DCM and its underlying mechanisms, pointing to the role of high glucose-induced oxidative stress and interrelated fibrosis. In STZ-induced diabetic mice, oral administration of THC (120 mg/kg/d) for 12 weeks significantly improved the cardiac function and ameliorated myocardial fibrosis and cardiac hypertrophy, accompanied by reduced reactive oxygen species (ROS) generation. Mechanically, THC administration remarkably increased the expression of the SIRT1 signaling pathway both in vitro and in vivo, further evidenced by decreased downstream molecule Ac-SOD2 and enhanced deacetylated production SOD2, which finally strengthened antioxidative stress capacity proven by repaired activities of SOD and GSH-Px and reduced MDA production. Additionally, THC treatment accomplished its antifibrotic effect by depressing the ROS-induced TGFβ1/Smad3 signaling pathway followed by reduced expression of cardiac fibrotic markers α-SMA, collagen I, and collagen III. Collectively, these finds demonstrated the therapeutic potential of THC treatment to alleviate DCM mainly by attenuating hyperglycemia-induced oxidative stress and fibrosis via activating the SIRT1 pathway

Spinful topological phases in acoustic crystals with projective PT symmetry

For the classification of topological phases of matter, an important consideration is whether a system is spinless or spinful, as these two classes have distinct symmetry algebra that gives rise to fundamentally different topological phases. However, only recently has it been realized theoretically that in the presence of gauge symmetry, the algebraic structure of symmetries can be projectively represented, which possibly enables the switch between spinless and spinful topological phases. Here, we report the experimental demonstration of this idea by realizing spinful topological phases in "spinless" acoustic crystals with projective space-time inversion symmetry. In particular, we realize a one-dimensional topologically gapped phase characterized by a 2Z winding number, which features double-degenerate bands in the entire Brillouin zone and two pairs of degenerate topological boundary modes. Our Letter thus overcomes a fundamental constraint on topological phases by spin classes.Published versionZ. G. acknowledges support from the National Natural Science Foundation of China under Grants No. 12104211, Shenzhen Science and Technology Innovation Commission under Grant No. 20220815111105001, and SUSTech under Grants No. Y01236148 and No. Y01236248. The work at Zhejiang University was sponsored by the Key Research and Development Program of the Ministry of Science and Technology under Grants No. 2022YFA1404704 (H. C.), No. 2022YFA1404902 (Y. Y.), and No. 2022YFA1405201 (Y. Y.), the National Natural Science Foundation of China (NNSFC) under Grants No. 11961141010 (H. C.), No. 62175215 (Y. Y.), and No. 61975176 (H. C.), the Fundamental Research Funds for the Central Universities (2021FZZX001-19) (Y. Y.), and the Excellent Young Scientists Fund Program (Overseas) of China (Y. Y.). H. S. acknowledges the support from the National Natural Science Foundation of China (Grants No. 12274183 and No. 12174159), and the National Key Research and Development Program of China (Grant No. 2020YFC1512403)