Metalens for Accelerated Optoelectronic Edge Detection under Ambient Illumination.

Analog systems may allow image processing, such as edge detection, with low computational power. However, most demonstrated analog systems, based on either conventional 4-f imaging systems or nanophotonic structures, rely on coherent laser sources for illumination, which significantly restricts their use in routine imaging tasks with ambient, incoherent illumination. Here, we demonstrated a metalens-assisted imaging system that can allow optoelectronic edge detection under ambient illumination conditions. The metalens was designed to generate polarization-dependent optical transfer functions (OTFs), resulting in a synthetic OTF with an isotropic high-pass frequency response after digital subtraction. We integrated the polarization-multiplexed metalens with a polarization camera and experimentally demonstrated single-shot edge detection of indoor and outdoor scenes, including a flying airplane, under ambient sunlight illumination. The proposed system showcased the potential of using polarization multiplexing for the construction of complex optical convolution kernels toward accelerated machine vision tasks such as object detection and classification under ambient illumination.

Emergence of layered nanoscale mesh networks through intrinsic molecular confinement self-assembly.

Block copolymer self-assembly is a powerful tool for two-dimensional nanofabrication; however, the extension of this self-assembly concept to complex three-dimensional network structures is limited. Here we report a simple method to experimentally generate three-dimensional layered mesh morphologies through intrinsic molecular confinement self-assembly. We designed triblock bottlebrush polymers with two Janus domains: one perpendicular and one parallel to the polymer backbone. The former enforces a lamellar superstructure that intrinsically confines the intralayer self-assembly of the latter, giving rise to a mesh-like monoclinic (54°) M15 network substructure with excellent long-range order, as well as a tetragonal (90°) T131 mesh. Numerical simulations show that the spatial constraints exerted on the polymer backbone drive the assembly of M15 and yield T131 in the strong segregation regime. This work demonstrates that intrinsic molecular confinement is a viable path to bottom-up assembly of new geometrical phases of soft matter, extending the capabilities of block copolymer nanofabrication.

Hierarchically engineered nanostructures from compositionally anisotropic molecular building blocks.

The inability to synthesize hierarchical structures with independently tailored nanoscale and mesoscale features limits the discovery of next-generation multifunctional materials. Here we present a predictable molecular self-assembly strategy to craft nanostructured materials with a variety of phase-in-phase hierarchical morphologies. The compositionally anisotropic building blocks employed in the assembly process are formed by multicomponent graft block copolymers containing sequence-defined side chains. The judicious design of various structural parameters in the graft block copolymers enables broadly tunable compositions, morphologies and lattice parameters across the nanoscale and mesoscale in the assembled structures. Our strategy introduces advanced design principles for the efficient creation of complex hierarchical structures and provides a facile synthetic platform to access nanomaterials with multiple precisely integrated functionalities.

Rapid Access to Diverse Multicomponent Hierarchical Nanostructures from Mixed-Graft Block Copolymers.

Multicomponent nanostructured materials assembled from molecular building blocks received wide attention due to their precisely integrated multifunctionalities. However, discovery of these materials with desirable composition and morphology was limited by their low synthetic scalability and narrow structural tuning window with given building blocks. Here, we report a scalable and diversity-oriented synthetic approach to hierarchically structured nanomaterials based on a few readily accessible building blocks. Mixed-graft block copolymers containing sequence-defined side chains were prepared through ring-opening metathesis copolymerization of three or four types of macromonomers. Intramolecularly defined interfaces promoted the formation of ordered hierarchical structures with lattice sizes tunable across multiple length scales. The same set of macromonomers were arranged and combined in different ways, providing access to diverse morphologies in the resultant structures.

Construction of multifunctional micro-patterned PALNMA/PDADMAC/PEGDA hydrogel and intelligently responsive antibacterial coating HA/BBR on Mg alloy surface for orthopedic application.

In recent years, magnesium alloys (MgA) have been reckoned as the most promising material of biomedical importance on account of its excellent degradable properties and mechanical properties mimicking natural bone tissues. However, MgA are prone to rapid corrosion under physiological conditions, causing toxicity around the neighboring tissues. In addition, they are susceptible to bacterial colonization, a detrimental factor for medical causes. In this study, antibacterial material coated hydrogel-based micro-patterns were developed on MgA to achieve long-term antibacterial, antifouling, osteogenic, and cell-compatible properties. First, the Mg(OH)2 nanosheet coating was prepared on the surface of MgA as a physical barrier to prevent the corrosion of MgA. Then the hydrogel micropatterns of poly(alendronate sodium methacrylate)/poly(dimethyldiallylammonium chloride)/poly(ethylene glycol) diacrylate (PALNMA/PDADMAC/PEGDA) of different sizes were constructed on the surface of the Mg(OH)2 coating using the photomask method. Finally, an intelligently responsive antibacterial material hyaluronic acid/berberine (HA/BBR) was coated on MgA-Mg(OH)2-PALNMA/PDADMAC/PEGDA patterns via layer-by-layer self-assembly. The excellent antifouling performance of the samples is attributed to the topological structure of the pattern. Interestingly, as the pattern size of PALNMA/PDADMAC/PEGDA decreases, the antibacterial, antifouling, and cell compatibility properties of the samples gradually improve. UV-Vis spectra and bacterial plate count indicate that HA/BBR coating provide a pH and hyaluronidase (HAase) dual-responsive surface to kill the attached bacteria quickly. Finally, the in vitro experiments demonstrate excellent blood compatibility, cell compatibility and osteogenic properties of the modified MgA samples. Therefore, the intelligent multifunctional assembly of MgA presented here has a promising future in the field of metal implant materials.

The effect of virtual reality training on the daily participation of patients: A meta-analysis.

BACKGROUND: Virtual reality (VR) training are regarded as promising new tools for rehabilitation, but the effect on patients' daily participation is controversial. This study aimed to evaluate the effect of virtual reality (VR) training on different types of patients' daily participation through a meta-analysis. METHODS: The PubMed, Cochrane central register of controlled trials, Embase, and web science databases were searched for studies published through September 2020. Thirty-five randomized controlled trials of virtual reality (VR) training compared with conventional treatment, Other electronic rehabilitation systems, usual care for various types of patients were included. All of the studies were available in English. Standardized mean differences (SMD), 95 % confidence intervals (CI), publication bias, and heterogeneity were calculated. RESULTS: The Virtual reality (VR) training group is better than the control group in daily participation improvement on all types of patients. There was a small, significant effect(p＜0.001; SMD = 0.25[95 %CI,0.14 to 0.36], I2 = 0.00 %). Observing only the type of Stroke, the VR training group is still better than the control group in improving patients' daily participation (p＜0.001, SMD = 0.24[95 %CI, 0.11 to 0.37], I2 = 0.00 %). Using the cumulative Meta-analysis method to observe the included literature according to the timeline, Using the cumulative Meta-analysis method to observe the included literature according to the timeline, and it has only achieved positive results since 2015 (Nam-YoNg Lee 2015, p = 0.048, SMD = 0.22[95 %CI,0.00 to 0.44]). The heterogeneity of the studies was not detected, but there is obvious publication bias. CONCLUSIONS: Because of controversy over obvious publication bias, we need to be cautious about the conclusion that VR is better than the control group in promoting the patient's daily participation.

Preparation of PVA Fluorescent Gel and Luminescence of Europium Sensitized by Terbium (III).

Polyvinyl alcohol (PVA) gel has a very wide range of applications in agriculture, military, industry, and other fields. As a widely used water-soluble polymer, PVA has good mechanical properties, excellent spinnability, good hydrophilicity, remarkable physical and chemical stability, good film formation, is non-polluting, and exhibits good natural degradation and biocompatibility. It is an ideal gel preparation material. Incorporation of rare-earth elements into PVA polymers can be used to prepare rare-earth luminescent gel materials. Results show that the luminescent efficiency of complexes is mainly related to their structure, ligand substituents, synergists, and the electronic configuration of doped rare-earth ions. Fluorescent gel films were prepared by adding europium, terbium, and europium/terbium co-doped into PVA, and their fluorescence properties were compared and analyzed. It was found that, in addition to the above factors, the sensitization of terbium to europium, and the fluorescence-quenching effect of hydroxyl groups, will influence the fluorescence properties. This has opened a new route for the application of rare-earth materials and may have value in the field of new materials.

Synthesis and Self-Assembly of Mixed-Graft Block Copolymers.

Mixed-graft block copolymers (mGBCPs) consist of two or more types of polymeric side chains grafted on a linear backbone in a random, alternating, or pseudo-alternating sequence. They can phase-separate with the backbone serving as the interface of the blocks, and the side chains dominate their self-assembly behavior. mGBCPs are an accessible polymer architecture for exploring the idea of encoding polymer properties through the macromolecular architecture, as there are two distinct structural components that can be tuned: the backbone and the side chains. In this Concept article, the current literature on the synthesis of mGBCPs is reviewed, and the advantages and disadvantages of each synthetic method are noted. The self-assembly of mGBCPs is also discussed where possible. Finally, directions for future research on mGBCP synthesis and self-assembly are suggested.

Site-Specifically Initiated Controlled/Living Branching Radical Polymerization: A Synthetic Route toward Hierarchically Branched Architectures.

Controlled/living radical polymerization was developed to synthesize branched polyacrylates and polystyrene with tunable degrees of branching and low dispersities. This method is based on a polymerization-induced branching process that occurs when n-butyl α-bromoacrylate is copolymerized under atom transfer radical polymerization conditions. This novel branching polymerization demonstrates excellent synthetic versatility, enabling the preparation of complex macromolecular architectures constructed from branched-polymer building blocks.