Micro/Nanometer‐Structured Scaffolds for Regeneration of Both Cartilage and Subchondral Bone

Treatment of osteochondral defects remains a great challenge in clinical practice because cartilage and subchondral bone possess significantly different physiological properties. In this study, the controlled surface micro/nanometer structure of bioactive scaffolds in a combination of biomaterial chemistry is harnessed to address this issue. Model bioactive biomaterials, bredigite (BRT) scaffolds, with controlled surface micro/nanostructure are successfully fabricated by combining 3D printing with a hydrothermal process. It is found that the growth of micro/nano–calcium phosphate crystals on the surface of BRT scaffolds notably enhances their compressive strength by healing the microcracks on the strut surface. The micro/nanostructured surface distinctly facilitates the spread and differentiation of chondrocytes by activating integrin αvb1 and α5b1 heterodimers, regulates cell morphology, and promotes osteogenic differentiation of rabbit bone marrow stromal cells (rBMSCs) through the synergetic effect of integrin α5b1 and RhoA, in which the microrod surface demonstrates the highest stimulatory effect on the differentiation of chondrocytes and rBMSCs. The in vivo study shows that the micro/nanostructured surface of the 3D printed scaffolds obviously promotes the regeneration of both cartilage and subchondral bone tissues. This study suggests that the construction of controlled micro/nanostructured surface in porous 3D scaffolds offers a smart strategy to induce bilineage bioactivities for osteochondral regeneration.     

A Room‐Temperature High‐Conductivity Metal Printing Paradigm with Visible‐Light Projection Lithography

Fabricating electronic devices require integrating metallic conductors and polymeric insulators in complex structures. Current metal‐patterning methods such as evaporation and laser sintering require vacuum, multistep processes, and high temperature during sintering or postannealing to achieve desirable electrical conductivity, which damages low‐temperature polymer substrates. Here reports a facile ecofriendly room‐temperature metal printing paradigm using visible‐light projection lithography. With a particle‐free reactive silver ink, photoinduced redox reaction occurs to form metallic silver within designed illuminated regions through a digital mask on substrate with insignificant temperature change (<4 °C). The patterns exhibit remarkably high conductivity achievable at room temperature (2.4 × 10⁷ S m^?1, ≈40% of bulk silver conductivity) after simple room‐temperature chemical annealing for 1–2 s. The finest silver trace produced reaches 15 µm. Neither extra thermal energy input nor physical mask is required for the entire fabrication process. Metal patterns were printed on various substrates, including polyethylene terephthalate, polydimethylsiloxane, polyimide, Scotch tape, print paper, Si wafer, glass coverslip, and polystyrene. By changing inks, this paradigm can be extended to print various metals and metal–polymer hybrid structures. This method greatly simplifies the metal‐patterning process and expands printability and substrate materials, showing huge potential in fabricating microelectronics with one system.     

Anodic Synthesis of Hierarchical SnS/SnOx Hollow Nanospheres and Their Application for High‐Performance Na‐Ion Batteries

Constructing hollow nanostructures is attractive for both fundamental research and practical applications. However, how to prepare hollow nanostructures in a simple, scalable, and cost‐effective way still remains a great challenge. In this study, for the first time, the anodization technique is applied to construct hollow nanostructures. Specifically, hollow nanospheres of SnS/SnO_x with a hierarchical porous structure are self‐assembled directly on the Sn substrate, via a convenient one‐step anodization method. When applied for sodium‐ion batteries, the thus fabricated SnS/SnO_x hollow nanospheres on the substrate readily serve as a binder‐free electrode, delivering remarkably high cycling stability and rate capability.     

Photoelectric Synaptic Plasticity Realized by 2D Perovskite

Recently, several light‐stimulated artificial synaptic devices have been proposed to mimic photonic synaptic plasticity for neuromorphic computing. Here, the photoelectric synaptic plasticity based on 2D lead‐free perovskite ((PEA)₂SnI₄) is demonstrated. The devices show a photocurrent activation in response to a light stimulus in a neuron‐like way and exhibit several essential synaptic functions such as short‐term plasticity (STP) and long‐term plasticity (LTP) as well as their transmission based on spike frequency control. The strength of synaptic connectivity can be effectively modulated by the duration, irradiance, and wavelength of light spikes. The ternary structure of (PEA)₂SnI₄ causes it to possess varied photoelectric properties by composition control, which enhances the complexity and freedoms required by neuromorphic computing. The physical mechanisms of the memory effect are attributed to two distinct lifetimes of photogenerated carrier trapping/detrapping processes modulated by controlling the proportion of Sn vacancies. This work demonstrates the great potential of (PEA)₂SnI₄ as a platform to develop future multifunctional artificial neuromorphic systems.     

FAPbI3 Flexible Solar Cells with a Record Efficiency of 19.38% Fabricated in Air via Ligand and Additive Synergetic Process

Compared with silicon‐based solar cells, organic–inorganic hybrid perovskite solar cells (PSCs) possess a distinct advantage, i.e., its application in the flexible field. However, the efficiency of the flexible device is still lower than that of the rigid one. First, it is found that the dense formamidinium (FA)‐based perovskite film can be obtained with the help of N‐methyl‐2‐pyrrolidone (NMP) via low pressure‐assisted method. In addition, CH₃NH₃Cl (MACl) as the additive can preferentially form MAPbCl_3?xI_x perovskite seeds to induce perovskite phase transition and crystal growth. Finally, by using FAI·PbI₂·NMP+x%MACl as the precursor, i.e., ligand and additive synergetic process, a FA‐based perovskite film with a large grain size, high crystallinity, and low trap density is obtained on a flexible substrate under ambient conditions due to the synergetic effect, e.g., MACl can enhance the crystallization of the intermediate phase of FAI·PbI₂·NMP. As a result, a record efficiency of 19.38% in flexible planar PSCs is achieved, and it can retain about 89% of its initial power conversion efficiency (PCE) after 230 days without encapsulation under ambient conditions. The PCE retains 92% of the initial value after 500 bending cycles with a bending radii of 10 mm. The results show a robust way to fabricate highly efficient flexible PSCs.     

Photoelectrochemical Synthesis of Ammonia with Black Phosphorus

Efficient production of ammonia using environmentally friendly techniques under ambient conditions is crucial to renewable energy storage and industrial applications, and catalysts with new reaction pathways are highly desirable. In this work, black phosphorus (BP) is used as a metal‐free 2D catalyst for the photoelectrochemical (PEC) nitrogen reduction reaction (NRR). The electrode is fabricated by layer‐by‐layer assembly of BP nanosheets on an indium tin oxide substrate. The PEC NRR activity in the N₂ saturated aqueous electrolyte without a sacrificial agent is excellent, as exemplified by an ammonia yield rate of 102.4 µg h^?1 mgcat.^?1 and Faradaic efficiency of 23.3% at ?0.4 V, which are the best among nonmetal catalysts for synthesis of ammonia by photocatalysis and electrocatalysis. Furthermore, the BP electrode shows excellent stability after 6 consecutive cycles. The excellent PEC catalytic properties are attributed to the light excitation enhanced electrocatalytic process and that the external bias promoted photocatalytic process improves ammonia production synergistically. The results not only demonstrate the great potential of BP in PEC catalysis, but also identify a promising technique to produce ammonia under ambient conditions using solar energy and electric energy.     

Retraction: 3D Printing of Bilineage Constructive Biomaterials for Bone and Cartilage Regeneration

Adv. Funct. Mater. 2017 , 27, 1703117 DOI: 10.1002/adfm.201703117 The above article, first published online on 31 July 2017 in Wiley Online Library ( https://doi.org/10.1002/adfm.201703117 ) and corrected on 19 March 2019 ( https://doi.org/10.1002/adfm.201900376 ) has been retracted by agreement with the authors, the journal Editor‐in‐Chief, and Wiley‐VCH Verlag GmbH & Co. KGaA. The retraction has been agreed upon due to several flawed figures as published in the article, containing duplicate images, which calls the validity of these data into question. Reference C. Deng, Q. Yao, C. Feng, J. Li, L. Wang, G. Cheng, M. Shi, L. Chen, J. Chang, C. Wu, Adv. Funct. Mater. 2017 , 27, 1703117.     

Metasurface‐based low‐profile high‐gain substrate‐integrated Fabry‐Pérot cavity antenna

A metasurface‐based substrate integrated Fabry‐Pérot cavity (FPC) antenna is presented for improved radiation performance associated with the low profile. A novel partially reflective planar (PRS) artificial magnetic conductor (AMC) structure is proposed as the upper reflector of the substrate integrated FP resonant cavity. A microstrip patch antenna is embedded inside the cavity as a feed. The proposed antenna is designed to operate at 9.35 GHz with the maximum realized gain of 14.2 dBi and the overall profile of λ₀/10 (λ₀ is the operating wavelength in free space). The low‐profile performance of the proposed design outperforms any previous substrate‐integrated FPC antenna design with this gain performance. The influences of the FP cavity on the reduction of the antenna profile and the enhancement of the antenna gain are also investigated. Good agreement between the measured and simulated results validates the feasibility of the analysis and design approach.     

杨房沟水电站EPC模式下工程变更管理

在工程建设发展的今天,EPC总承包模式是大势所趋。杨房沟水电站开创了国内百万千瓦级大型水电站EPC模式建设的先河。EPC模式下的变更管理是一项重要的管理工作,从工作界面划分、设计深度、招标范围、风险转移等方面,对该工程EPC模式下的工程变更管理进行了思考和总结,希望为类似工程提供有益参考。