No abstract

The emerging metasurfaces with the exceptional capability of manipulating an arbitrary wavefront have revived the holography with unprecedented prospects. However, most of the reported metaholograms suffer from limited polarization controls for a restrained bandwidth in addition to their complicated meta-atom designs with spatially variant dimensions. Here, we demonstrate a new concept of vectorial holography based on diatomic metasurfaces consisting of metamolecules formed by two orthogonal meta-atoms. On the basis of a simply linear relationship between phase and polarization modulations with displacements and orientations of identical meta-atoms, active diffraction of multiple polarization states and reconstruction of holographic images are simultaneously achieved, which is robust against both incident angles and wavelengths. Leveraging this appealing feature, broadband vectorial holographic images with spatially varying polarization states and dual-way polarization switching functionalities have been demonstrated, suggesting a new route to achromatic diffractive elements, polarization optics, and ultrasecure anticounterfeiting.

A copper-catalyzed method for the preparation of ynamides has been identified that proceeds via aerobic oxidative coupling of terminal alkynes with various nitrogen nucleophiles, including cyclic carbamates, amides and ureas, and N-alkyl-arylsulfonamides and indoles.

Accumulation of dysfunctional mitochondria is one of the hallmarks in Alzheimer's disease (AD). Mitophagy, a selective autophagy for eliminating damaged mitochondria, constitutes a key cellular pathway in mitochondrial quality control. Recent studies established that acute depolarization of mitochondrial membrane potential (Δψm) using Δψm dissipation reagents in vitro induces Parkin-mediated mitophagy in many non-neuronal cell types or neuronal cell lines. However, neuronal pathways inducing mitophagy, particularly under pathophysiological relevant context in AD mouse models and patient brains, are largely unknown. Here, we reveal, for the first time, that Parkin-mediated mitophagy is robustly induced in mutant hAPP neurons and AD patient brains. In the absence of Δψm dissipation reagents, hAPP neurons exhibit increased recruitment of cytosolic Parkin to depolarized mitochondria. Under AD-linked pathophysiological conditions, Parkin translocation predominantly occurs in the somatodendritic regions; such distribution is associated with reduced anterograde and increased retrograde transport of axonal mitochondria. Enhanced mitophagy was further confirmed in AD patient brains, accompanied with depletion of cytosolic Parkin over disease progression. Thus, aberrant accumulation of dysfunctional mitochondria in AD-affected neurons is likely attributable to inadequate mitophagy capacity in eliminating increased numbers of damaged mitochondria. Altogether, our study provides the first line of evidence that AD-linked chronic mitochondrial stress under in vitro and in vivo pathophysiological conditions effectively triggers Parkin-dependent mitophagy, thus establishing a foundation for further investigations into cellular pathways in regulating mitophagy to ameliorate mitochondrial pathology in AD.

Phase, polarization, amplitude, and frequency represent the basic dimensions of light, playing crucial roles for both fundamental light-material interactions and all major optical applications. Metasurfaces have emerged as a compact platform to manipulate these knobs, but previous metasurfaces have limited flexibility to simultaneous control them. A multi-freedom metasurface that can simultaneously and independently modulate phase, polarization, and amplitude in an analytical form is introduced, and frequency multiplexing is further realized by a k-space engineering technique. The multi-freedom metasurface seamlessly combines geometric Pancharatnam-Berry phase and detour phase, both of which are frequency independent. As a result, it allows complex-amplitude vectorial hologram at various frequencies based on the same design strategy, without sophisticated nanostructure searching of massive geometric parameters. Based on this principle, full-color complexamplitude vectorial meta-holograms in the visible are experimentally demonstrated with a metal-insulator-metal architecture, unlocking the longsought full potential of advanced light field manipulation through ultrathin metasurfaces.functional layers, emerge as a desirable platform to manipulate the light field at will with large control and flexibility. [3][4][5][6][7] Exciting applications have already been demonstrated on the metasurface platform, including flat diffractive and polarization optical components, much more compact and lightweight than conventional bulky counterparts. By engineering the scattering properties of the individual metaelements constituting the metasurface to mold the geometric phase, resonant phase or propagation phase, we are able to control phase, [8,9] amplitude, [10,11] polarization, [12,13] or frequency [14][15][16] of light, leading to high-efficiency metalenses, [9] high-fidelity holograms, [8] broadband polarization components, [12,17] and highperformance biosensors. [15] However, these ultrathin components tend to focus on single-dimensional light manipulation, controlling either the local phase, or amplitude, or polarization, or frequency, at a time, inherently limiting potential opportunities. For example, metasurface holograms and metalenses based on resonant phase and propagation phase are typically limited to a narrow range of frequencies. [18,19] Geometric Pancharatnam-Berry (P-B) phase metasurfaces operate over broader bandwidths, but they are restricted to circular polarization only. [8] To improve the performance and enrich the functionality of metasurfaces for a broader range of applications, independent