Organic-inorganic metal halide perovskites have drawn a great deal of attention due to their supreme optical and electrical properties and their potential in future application in optoelectronic devices. Here, we carry out finite-difference time-domain (FDTD) simulation on different experimentally realistic structures of perovskite solar cells (PSC) and optimize their parameters with assistance of neural network (NN). We find an optimized structure with 30.48% enhancement comparing to planar structure and the fact that with properly design, 300-nm-thick nano-textured structure can outperform 900-nm-thick planar structure. We believe that light trapping structure is essential in thin film PSCs and also has a great potential in lead-free PSCs.
Fluorescent nanoprobes are indispensable tools to monitor and analyze biological species and dynamic biochemical processes in cells and living bodies. Conventional nanoprobes have limitations in obtaining imaging signals with high precision and resolution because of the interference with biological autofluorescence, off-target effects, and lack of spatiotemporal control. As a newly developed paradigm, light-activated nanoprobes, whose imaging and sensing activity can be remotely regulated with light irradiation, show good potential to overcome these limitations. Herein, recent research progress on the design and construction of light-activated nanoprobes to improve bioimaging and sensing performance in complex biological systems is introduced. First, recent innovative strategies and their underlying mechanisms for light-controlled imaging are reviewed, including photoswitchable nanoprobes and phototargeted nanosystems. Subsequently, a short highlight is provided on the development of light-activatable nanoprobes for biosensing, which offer possibilities for the remote control of biorecognition and sensing activity in a precise manner both temporally and spatially. Finally, perspectives and challenges in light-activated nanoprobes are commented.
Abstract A novel pattern strategy of a nanomaterial network that can self-assemble onto prepatterned soft substrate to realize ultra-transparent electronics is presented. The approach detailed is based on the combination of nanomaterials' self-assembly at the water–air interface to form nanomaterial networks and the breakage phenomenon of water–nanomaterial membranes to form designed patterns. With the comprehensive investigation of this phenomenon, nanomaterial networks are manipulated to attach to prepatterned sidewalls. This leads to a remarkable transparency improvement without conductive property decline. Three 1D nanomaterials with various geometries are demonstrated to verify the universal feature of this pattern strategy, including silver nanowire (AgNW), carbon nanotube, and zinc oxide nanowire. Furthermore, sequential layer-by-layer deposition of several 1D nanomaterials has also been demonstrated by using the proposed approach, revealing an attractive potential of multiple-junction transparent electronics. The fabricated micro-grid structure of AgNWs with a line width of 5 µm and pitch of 150 µm has a sheet resistance of 37.88 Ω sq−1 and an optical transmittance of 86.06%. This fabrication strategy opens up opportunities for different nanomaterials in many transparent and wearable applications.
Stretchable electronics have great importance in the application of wearable device and electronic skin. The balance and improvements of mechanical stretchability and electronic performance are the great challenges that restrict the further development of stretchable electronics. In order to achieve stretchable electronics, it is crucial to choose the proper substrates, among which PDMS is the most commonly used polymer due its easy fabrication and low cost. In this paper, we propose a novel strategy and fabricate localized and precise modulus-controlled PDMS for both two/three-dimensional stretchable electronics. Based on a secondary cross-link effect, the modulus of cured PDMS can be enhanced and precisely controlled by spin-coating different mass of curing agent. Using laser-cutted PI mask, the modulus-enhanced region can be defined by users. Through this simple method, the functional conductive thin-film materials (Gold/Ag nanowires/Reduced Graphene oxide) can be well protected when the structural layer is stretched and the “Barrel Effect” of multi-materials film (different material films possess different stretchability) on one piece of substrate can also be solved. Besides, the localizedly modified PDMS as a substrate can form different 3D buckling structures on it by pre-stretching and releasing process compared with uniform PDMS, which shows a new way to control the 3D buckling structure.
The maintenance of terminally differentiated cells, especially hepatocytes, in vitro has proven challenging. Here we demonstrated the long-term in vitro maintenance of primary human hepatocytes (PHHs) by modulating cell signaling pathways with a combination of five chemicals (5C). 5C-cultured PHHs showed global gene expression profiles and hepatocyte-specific functions resembling those of freshly isolated counterparts. Furthermore, these cells efficiently recapitulated the entire course of hepatitis B virus (HBV) infection over 4 weeks with the production of infectious viral particles and formation of HBV covalently closed circular DNA. Our study demonstrates that, with a chemical approach, functional maintenance of PHHs supports long-term HBV infection in vitro, providing an efficient platform for investigating HBV cell biology and antiviral drug screening.
Identifying drivers behind biodiversity recovery is critical to promote efficient ecological restoration. Yet to date, for secondary forests in China there is a considerable uncertainty concerning the ecological drivers that affect plant diversity recovery. Following up on a previous published meta-analysis on the patterns of species recovery across the country, here we further incorporate data on the logging history, climate, forest landscape and forest attribute to conduct a nationwide analysis of the main drivers influencing the recovery of woody plant species richness in secondary forests. Results showed that regional species pool exerted a positive effect on the recovery ratio of species richness and this effect was stronger in selective cutting forests than that in clear cutting forests. We also found that temperature had a negative effect, and the shape complexity of forest patches as well as the percentage of forest cover in the landscape had positive effects on the recovery ratio of species richness. Our study provides basic information on recovery and resilience analyses of secondary forests in China.
Abstract Seismic anisotropy records past and present tectonic deformations and provides important constraints for understanding the structure and dynamics of the Earth's interior. In this work, we use tremendous amounts of high-quality P wave arrival times from local and regional earthquakes to determine a high-resolution tomographic model of 3-D P wave azimuthal anisotropy down to 1,000-km depth beneath East Asia. Our results show that trench-parallel fast-velocity directions (FVDs) are visible in the shallow portion of the subducting Pacific slab (<80 km), whereas the deeper portion of the Pacific slab mainly exhibits trench-normal FVDs, except for the stagnant slab in the mantle transition zone (MTZ) where obvious NE-SW FVDs are revealed. The FVDs in the subslab mantle change from a subduction-parallel trend at depths of 80–400 km to a subduction-normal trend in the MTZ. Large-scale low-velocity anomalies are revealed beneath the Philippine Sea plate where the FVD is NE-SW. The FVDs along the Izu-Bonin arc and in a slab gap exhibit a striking anticlockwise toroidal trend. All these features may reflect complex 3-D flows in the mantle wedge due to tearing and dehydration processes of the subducting Pacific slab. The subducting Pacific slab is split at 300-km depth under the Bonin arc and then penetrates into the lower mantle, whereas under East Asia the Pacific slab becomes stagnant in the MTZ and reaches the North-South Gravity Lineament in China. The intraplate volcanoes in East Asia are caused by hot and wet upwelling flows in the big mantle wedge above the stagnant Pacific slab.