Programmable locomotion of responsive hydrogels has gained increasing attention for potential applications in soft robotics, microfluidic components, actuators, and artificial muscle. Modulation of ...hydrogel pore structures is essential for tailoring their mechanical strength, response speeds, and motion behaviors. Conventional methods forming hydrogels with homogeneous or stepwise‐distributed pore structures are limited by the required compromise to simultaneously optimize these aspects. Here, a heterobifunctional crosslinker enabled hydrothermal process is introduced to synthesize responsive hydrogels with well‐defined gradient pore construction. According to gradient porosity controls, the hydrogels simultaneously exhibit rapid responses to external stimuli, high elasticity/compressibility, and programmable locomotion capability. By incorporating polypyrrole nanoparticles as photothermal transducers, photo/thermal responsive composite hydrogels are formed to enable programmable control of locomotion such as bending, curving, twisting, and octopus‐like swimming under near‐infrared laser stimulation. The tunable pore structures, mechanical properties, and locomotion of this new class of materials make these gradient porous hydrogels potentially suitable for a variety of applications.
Gradient porous elastic hydrogels with rapid and programmable locomotion to thermal‐/photostimulation are obtained through an effective hydrothermal route. According to the gradient porosity control, the hydrogels simultaneously exhibit rapid responses, high elasticity, and anisotropic locomotion. The hydrothermally induced hydrogelation mechanism is applicable to other thermal‐responsive monomers and crosslinkers, opening new avenues for modulating the pore structures of soft materials.
Achieving efficient photon upconversion under low irradiance is not only a fundamental challenge but also central to numerous advanced applications spanning from photovoltaics to biophotonics. ...However, to date, almost all approaches for upconversion luminescence intensification require stringent controls over numerous factors such as composition and size of nanophosphors. Here, we report the utilization of dielectric microbeads to significantly enhance the photon upconversion processes in lanthanide-doped nanocrystals. By modulating the wavefront of both excitation and emission fields through dielectric superlensing effects, luminescence amplification up to 5 orders of magnitude can be achieved. This design delineates a general strategy to converge a low-power incident light beam into a photonic hotspot of high field intensity, while simultaneously enabling collimation of highly divergent emission for far-field accumulation. The dielectric superlensing-mediated strategy may provide a major step forward in facilitating photon upconversion processes toward practical applications in the fields of photobiology, energy conversion, and optogenetics.
In nature, individual cells contain multiple isolated compartments in which cascade enzymatic reactions occur to form essential biological products with high efficiency. Here, we report a ...cell-inspired design of functional hydrogel particles with multiple compartments, in which different enzymes are spatially immobilized in distinct domains that enable engineered, one-pot, tandem reactions. The dense packing of different compartments in the hydrogel particle enables effective transportation of reactants to ensure that the products are generated with high efficiency. To demonstrate the advantages of micro-environmental modifications, we employ the copolymerization of acrylic acid, which leads to the formation of heterogeneous multi-compartmental hydrogel particles with different pH microenvironments. Upon the positional assembly of glucose oxidase and magnetic nanoparticles, these hydrogel particles are able to process a glucose-triggered, incompatible, multistep tandem reaction in one pot. Furthermore, based on the high cytotoxicity of hydroxyl radicals, a glucose-powered therapeutic strategy to kill cancer cells was approached.Cells contain isolated compartments where cascade enzymatic biochemical reactions occur to form essential biological products with high efficiency. Here the authors produce functional hydrogel particles with multiple compartments via microfluidics that contain spatially immobilized natural enzymes in distinct domains for one-pot, tandem reactions.
Deep reinforcement learning (DRL) has emerged as the dominant approach to achieving successive advancements in the creation of human-wise agents. By leveraging neural networks as decision-making ...controllers, DRL supplements traditional reinforcement methods to address the curse of dimensionality in complicated tasks. However, agents in complicated environments are likely to get stuck in sub-optimal solutions. In such cases, the agent inadvertently turns into a “zombie” owing to its short-term vision and harmful behaviors. In this study, we use human learning strategies to adjust agent behaviors in high-dimensional environments. Therefore, the agent behaves predictably and succeeds in attaining its designated goal. In summary, the contribution of this study is two-fold. First, we introduce a lightweight workflow that enables a nonexpert to preserve a certain level of safety in AI systems. Specifically, the workflow involves a novel concept of a target map and a multi-agent behavioral control system named Multi-Policy Control System (MPCS). MPCS successfully controls agent behaviors in real time without involving the burden of human feedback. Second, we develop a multi-agent game named Tank Battle that provides a configurable environment to examine agent behaviors and human-agent interactions in DRL. Finally, simulation results show that agents guided by MPCS outperform agents that do not use MPCS with respect to the mean of total rewards and human-like behaviors in complicated environments such as Seaquest and Tank Battle.
Organic–inorganic lead halide perovskites have shown great future for application in solar cells owing to their exceptional optical and electronic properties. To achieve high‐performance perovskite ...solar cells, a perovskite light absorbing layer with large grains is desirable in order to minimize grain boundaries and recombination during the operation of the device. Herein, a simple yet efficient approach is developed to synthesize perovskite films consisting of monolithic‐like grains with micrometer size through in situ deposition of octadecylamine functionalized single‐walled carbon nanotubes (ODA‐SWCNTs) onto the surface of the perovskite layer. The ODA‐SWCNTs form a capping layer that controls the evaporation rate of organic solvents in the perovskite film during the postthermal treatment. This favorable morphology in turn dramatically enhances the short‐circuit current density of the perovskite solar cells and almost completely eliminates the hysteresis. A maximum power conversion efficiency of 16.1% is achieved with an ODA‐SWCNT incorporated planar solar cell using (FA0.83MA0.17)0.95Cs0.05Pb(I0.83Br0.17)3 as light absorber. Furthermore, the perovskite solar cells with ODA‐SWCNT demonstrate extraordinary stability with performance retention of 80% after 45 d stability testing under high humidity (60–90%) environment. This work opens up a new avenue for morphology manipulation of perovskite films and enhances the device stability using carbon material.
In situ deposition of a capping layer of octadecylamine functionalized single‐walled carbon nanotubes onto the surface of perovskite films generates beneficial effects including improved perovskite grain size, reduced ion migration, and water repellency. Consequently, improved efficiency, stability, and reduced hysteresis of perovskite solar cells (PSCs) are achieved. This work demonstrates the potential of carbon nanotubes in enhancing the performance of PSCs.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly pathogenic virus that has caused the global COVID-19 pandemic. Tracing the evolution and transmission of the virus is crucial ...to respond to and control the pandemic through appropriate intervention strategies. This paper reports and analyses genomic mutations in the coding regions of SARS-CoV-2 and their probable protein secondary structure and solvent accessibility changes, which are predicted using deep learning models. Prediction results suggest that mutation D614G in the virus spike protein, which has attracted much attention from researchers, is unlikely to make changes in protein secondary structure and relative solvent accessibility. Based on 6324 viral genome sequences, we create a spreadsheet dataset of point mutations that can facilitate the investigation of SARS-CoV-2 in many perspectives, especially in tracing the evolution and worldwide spread of the virus. Our analysis results also show that coding genes E, M, ORF6, ORF7a, ORF7b and ORF10 are most stable, potentially suitable to be targeted for vaccine and drug development.
Abstract In this article, we consider the weighted conical Radon transform—the transform is motivated by Compton camera imaging as well as optical tomography. Our contribution involves introducing ...new inversion formulas for the weighted conical Radon transform, including explicit formulas and properties associated with convolution frames. Furthermore, we propose reconstruction formulas that solve for variety weighted parameters in the two-dimensional space.
Light‐directed forces have been widely used to pattern micro/nanoscale objects with precise control, forming functional assemblies. However, a substantial laser intensity is required to generate ...sufficient optical gradient forces to move a small object in a certain direction, causing limited throughput for applications. A high‐throughput light‐directed assembly is demonstrated as a printing technology by introducing gold nanorods to induce thermal convection flows that move microparticles (diameter = 40 µm to several hundreds of micrometers) to specific light‐guided locations, forming desired patterns. With the advantage of effective light‐directed assembly, the microfluidic‐fabricated monodispersed biocompatible microparticles are used as building blocks to construct a structured assembly (≈10 cm scale) in ≈2 min. The control with microscale precision is approached by changing the size of the laser light spot. After crosslinking assembly of building blocks, a novel soft material with wanted pattern is approached. To demonstrate its application, the mesenchymal stem‐cell‐seeded hydrogel microparticles are prepared as functional building blocks to construct scaffold‐free tissues with desired structures. This light‐directed fabrication method can be applied to integrate different building units, enabling the bottom‐up formation of materials with precise control over their internal structure for bioprinting, tissue engineering, and advanced manufacturing.
A novel high throughput light‐directed assembly methodon the microscale is investigated by suspending gold nanorods (GNRs), as photothermal transducers, in a fluidic medium to induce thermoplasmonic convections for the assembly of building blocks fabricated through microfluidics. Because significant local thermoplasmonic convections are generated by precisely controlling the low‐power infrared laser spot size and direction, effective building block assembly with high resolution enabled the desired patterns.
A stable and efficient carrier transfer is a prerequisite for high-performance perovskite solar cells. With optimized additives, a significantly improved charge carrier transfer can be achieved at ...the interface of perovskite/2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino)-9,90-spirobifluorene (Spiro-OMeTAD) with significantly boosted photostability. Using time-dependent spectroscopic techniques, we investigated charge carrier and mobile-ion dynamics at the perovskite/Spiro-OMeTAD interface, where the Spiro-OMeTAD contains different bis(trifluoromethanesulfonyl)imide (TFSI) salts additives (Li-TFSI, Mg-TFSI2, Ca-TFSI2). The pristine response and the dynamic changes under continuous illuminations are presented, which is correlated to the different behaviors of mobile-ion accumulations at the perovskite/Spiro interface and ascribed to the improved hole mobilities in Spiro-OMeTAD, ultimately contributing to the favorable behaviors in solar cells. It is demonstrated that the hole mobility and conductivity of hole transport layers play an important role in suppressing mobile-ion accumulation at the interfaces of solar cells. With the engineering of mixed-cation mixed-halide perovskite, optimal engineering of additives in hole transport materials is an efficient strategy. Therefore, it should be emphasized for accelerating perovskite photovoltaic commercialization.
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