The mechanism of multiple organ dysfunction syndrome in patients with COVID-19.

In late 2019, an outbreak of coronavirus disease 2019 (COVID-19) arose, caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). This disease rapidly became a public health event of international concern. In addition to the most typical symptoms of dyspnea, numerous patients with COVID-19 exhibited systemic symptoms, such as cardiovascular disease, liver and kidney failure, and disorders in coagulation. At present, clinical data indicates that numerous patients who are critically ill die from multiple organ dysfunction syndromes (MODS). Moreover, the entry of SARS-CoV-2 into cells causing severe pathology and progressive organ failure is precisely mediated by the human angiotensin-converting enzyme 2 protein. This plays a role in maintaining both fluid and electrolyte homeostasis, ensuring the stability of the internal environment. Therefore, the present review aimed to investigate the pathogenesis of MODS caused by SARS-CoV-2 infection based on the current clinical data and previous studies.

Metasurfaces with Planar Chiral Meta-Atoms for Spin Light Manipulation.

Spin light (i.e., circularly polarized light) manipulation based on metasurfaces with a controlled geometric phase (i.e., Pancharatnam-Berry (PB) phase) has achieved great successes according to its convenient design and robust performances, by which the phase control is mainly determined by the rotation angle of each meta-atom. This PB phase can be regarded as a global effect for spin light; here, we propose a local phase manipulation for metasurfaces with planar chiral meta-atoms. Planar chiral meta-atoms break fundamental symmetry restrictions and do not need a rotation for these kinds of meta-atoms to manipulate the spin light, which significantly expands the functionality of metasurface as it is incorporated with other modulations (e.g., PB phase, propagation phase). As an example, spin-decoupled holographic imaging is demonstrated with robust and broadband properties. Our work definitely enriches the design of metasurfaces and may trigger more exciting chiral-optics applications.

Cavity-enhanced metallic metalens with improved Efficiency.

Metasurfaces are made of subwavelength nanoantennas with a flat, ultrathin architecture, and strong capability in manipulating the propagation of light by flexible modulations on its phase, amplitude, and polarization. Conventional metallic metalenses always suffer from its low efficiencies due to large intrinsic loss. Here, we demonstrate a cavity enhanced bilayer metalens composed of aluminum nanobars and its complementary structures. The focusing and imaging experiments definitely show an improved efficiency of such kind of bilayer metalens compared with its single layer counterpart. Detailed theoretical analyses based on full-wave simulations are carried out with respect to different cavity lengthes and working wavelengths, which reveals that the improvement rightly attributes to enhanced cavity mode. Our design will not only improve the working efficiency for metalens with simplified manufacturing procedure, but also indicates more possibilities by employing the metal as electrodes.

Spectral tomographic imaging with aplanatic metalens.

Tomography is an informative imaging modality that is usually implemented by mechanical scanning, owing to the limited depth-of-field (DOF) in conventional systems. However, recent imaging systems are working towards more compact and stable architectures; therefore, developing nonmotion tomography is highly desirable. Here, we propose a metalens-based spectral imaging system with an aplanatic GaN metalens (NA = 0.78), in which large chromatic dispersion is used to access spectral focus tuning and optical zooming in the visible spectrum. After the function of wavelength-switched tomography was confirmed on cascaded samples, this aplanatic metalens is utilized to image microscopic frog egg cells and shows excellent tomographic images with distinct DOF features of the cell membrane and nucleus. Our approach makes good use of the large diffractive dispersion of the metalens and develops a new imaging technique that advances recent informative optical devices.