Background Health care workers at the frontline are facing a substantial risk of infection during the coronavirus disease 2019 (COVID-19) outbreak. Methods We acquired information and data on the general information, infection and death status of health care workers in Wuhan during the COVID-19 outbreak and completed statistical analyses. Results We have obtained the data on 2,457 infected cases among health care workers in Wuhan, China. More than half of the infected individuals were nurses (52.06%), while 33.62% of infected cases were doctors and 14.33% of cases were medical staff. In particular, the case infection rate of nurses (2.22%) was remarkably higher than that of doctors (1.92%). Most infected cases among health care workers were female (72.28%). A majority of the infected health care workers (89.26%) came from general hospitals, followed by specialized hospitals (5.70%) and community hospitals (5.05%). The case infection rate of health care workers (2.10%) was dramatically higher than that of non-health care workers (0.43%). The case fatality rate of health care workers (0.69%) was significantly lower than that of non-health care workers (5.30%). Conclusions The infection risk of HCWs is clearly higher than that of non-HCWs. HCWs play an essential role in fighting the pandemic. The analysis of the infection status of HCWs is essential to attract enough attention from the public, provide effective suggestions for government agencies and improve protective measures for HCWs.

CitationAcoustic cloaking by a near-zero-index phononic crystal 2014, 104 (16):161904 Applied Physics Letters

We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

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Artificial honeycomb lattices with Dirac cone dispersion provide a macroscopic platform to study the massless Dirac quasiparticles and their novel geometric phases. In this paper, a quadruple-degenerate state is achieved at the center of the Brillouin zone in a two-dimensional honeycomb lattice phononic crystal, which is a result of accidental degeneracy of two double-degenerate states. In the vicinity of the quadruple-degenerate state, the dispersion relation is linear. Such quadruple degeneracy is analyzed by rigorous representation theory of groups. Using method, a reduced Hamiltonian is obtained to describe the linear Dirac dispersion relations of this quadruple-degenerate state, which is well consistent with the simulation results. Near such accidental degeneracy, we observe some unique properties in wave propagating, such as defect-insensitive propagating character and the Talbot effect.

Background: Epithelial-to-mesenchymal transition (EMT) is a potential pathway leading to podocyte depletion and proteinuria in diabetic kidney disease (DKD). Here, we investigated the protective effects of Emodin (EMO) on high glucose (HG) induced-podocyte EMT in-vitro and in-vivo. Methods: Conditionally immortalized mouse podocytes were exposed to HG with 30μg /ml of EMO and 1μmol/ml of integrin-linked kinase (ILK) inhibitor QLT0267 for 24 h. Streptozotocin (STZ)-induced diabetic rats were treated with EMO at 20 mg· kg^-1· d^-1 and QLT0267 at 10 mg· kg^-1· w^-1 p.o., for 12 weeks. Albuminuria and blood glucose level were measured. Immunohistochemistry, immunofluorescence, western blotting and real-time PCR were used to detect expression of ILK, the epithelial marker of nephrin and the mesenchymal marker of desmin in-vitro and in-vivo. Results: HG increased podocyte ILK and desmin expression while decreased nephrin expression. However, EMO significantly inhibited ILK and desmin expression and partially restored nephrin expression in HG-stimulated podocytes. These in-vitro observations were further confirmed in-vivo. Treatment with EMO for 12 weeks attenuated albuminuria, renal histopathology and podocyte foot process effacement in diabetic rats. EMO also repressed renal ILK and desmin expression, preserved nephrin expression, as well as ameliorated albuminuria in STZ-induced diabetic rats. Conclusion: EMO ameliorated glucose-induced EMT and subsequent podocyte dysfunction partly through ILK and desmin inhibition as well as nephrin upregulatiotion, which might provide a potential novel therapeutic option for DKD.

In this work, we experimentally report the acoustic realization the two-dimensional (2D) Su-Schrieffer-Heeger (SSH) model in a simple network of airchannels. We analytically study the steady state dynamics of the system using a set of discrete equations for the acoustic pressure, leading to the 2D SSH Hamiltonian matrix without using tight binding approximation. By building an acoustic network operating in audible regime, we experimentally demonstrate the existence of topological band gap. More supremely, within this band gap we observe the associated edge waves even though the system is open to free space. Our results not only experimentally demonstrate topological edge waves in a zero Berry curvature system but also provide a flexible platform for the study of topological properties of sound waves.

Dirac cones are essential features of the electronic band structure of materials like graphene and topological insulators (TIs). Lately, this avenue has found a growing interest in classical wave physics by using engineered artificial lattices. Here, we demonstrate an acoustic 3D honeycomb lattice that features a Dirac hierarchy comprising an eightfold bulk Dirac cone, a 2D fourfold surface state Dirac cone, and a 1D twofold hinge state Dirac cone. The lifting of the Dirac degeneracy in each hierarchy authorizes the 3D lattice to appear as a first-order TI with 2D topological surface states, a second-order TI exhibiting 1D hinge states, and a third-order TI of 0D midgap corner states. Analytically we discuss the topological origin of the surface, hinge, and corner states, which are all characterized by out-of-plane and in-plane winding numbers. Our study offers new routes to control sound and vibration for acoustic steering and guiding, on-chip ultrasonic energy concentration, and filtering to name a few.