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"Wei, Hong"
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Inactivation of porcine endogenous retrovirus in pigs using CRISPR-Cas9
Xenotransplantation is a promising strategy to alleviate the shortage of organs for human transplantation. In addition to the concerns about pig-to-human immunological compatibility, the risk of cross-species transmission of porcine endogenous retroviruses (PERVs) has impeded the clinical application of this approach. We previously demonstrated the feasibility of inactivating PERV activity in an immortalized pig cell line. We now confirm that PERVs infect human cells, and we observe the horizontal transfer of PERVs among human cells. Using CRISPR-Cas9, we inactivated all of the PERVs in a porcine primary cell line and generated PERV-inactivated pigs via somatic cell nuclear transfer. Our study highlights the value of PERV inactivation to prevent cross-species viral transmission and demonstrates the successful production of PERV-inactivated animals to address the safety concern in clinical xenotransplantation.
Journal Article
Layered oxide cathodes for sodium‐ion batteries: From air stability, interface chemistry to phase transition
Sodium‐ion batteries (SIBs) are considered as a low‐cost complementary or alternative system to prestigious lithium‐ion batteries (LIBs) because of their similar working principle to LIBs, cost‐effectiveness, and sustainable availability of sodium resources, especially in large‐scale energy storage systems (EESs). Among various cathode candidates for SIBs, Na‐based layered transition metal oxides have received extensive attention for their relatively large specific capacity, high operating potential, facile synthesis, and environmental benignity. However, there are a series of fatal issues in terms of poor air stability, unstable cathode/electrolyte interphase, and irreversible phase transition that lead to unsatisfactory battery performance from the perspective of preparation to application, outside to inside of layered oxide cathodes, which severely limit their practical application. This work is meant to review these critical problems associated with layered oxide cathodes to understand their fundamental roots and degradation mechanisms, and to provide a comprehensive summary of mainstream modification strategies including chemical substitution, surface modification, structure modulation, and so forth, concentrating on how to improve air stability, reduce interfacial side reaction, and suppress phase transition for realizing high structural reversibility, fast Na+ kinetics, and superior comprehensive electrochemical performance. The advantages and disadvantages of different strategies are discussed, and insights into future challenges and opportunities for layered oxide cathodes are also presented. Recent progress in layered oxide cathodes for sodium‐ion batteries (SIBs) from air stability, interface chemistry, and phase transition are comprehensively summarized. The intrinsic degradation mechanisms behind electrochemical performance and mainstream modification strategies are systematically sorted out and analyzed. The remaining challenges, promising optimization strategies as well as endeavor directions to break current limitations are also presented for the future design of high‐performance layered oxide cathodes for SIBs.
Journal Article
Reconstitution and structure of a plant NLR resistosome conferring immunity
Nucleotide-binding, leucine-rich repeat receptors (NLRs) initiate immune responses when they sense a pathogen-associated effector. In animals, oligomerization of NLRs upon binding their effectors is key to downstream activity, but plant systems differ in many ways and their activation mechanisms have been less clear. In two papers, Wang et al. studied the composition and structure of an NLR called ZAR1 in the small mustard plant Arabidopsis (see the Perspective by Dangl and Jones). They determined cryo–electron microscopy structures that illustrate differences between inactive and intermediate states. The active, intermediate state of ZAR1 forms a wheel-like pentamer, called the resistosome. In this activated complex, a set of helices come together to form a funnel-shaped structure required for immune responsiveness and association with the plasma membrane. Science , this issue p. eaav5868 , p. eaav5870 ; see also p. 31 Structural, biochemical, and functional studies show how a plant immune resistosome complex mediates cell death and disease resistance. Nucleotide-binding, leucine-rich repeat receptors (NLRs) perceive pathogen effectors to trigger plant immunity. Biochemical mechanisms underlying plant NLR activation have until now remained poorly understood. We reconstituted an active complex containing the Arabidopsis coiled-coil NLR ZAR1, the pseudokinase RKS1, uridylated protein kinase PBL2, and 2′-deoxyadenosine 5′-triphosphate (dATP), demonstrating the oligomerization of the complex during immune activation. The cryo–electron microscopy structure reveals a wheel-like pentameric ZAR1 resistosome. Besides the nucleotide-binding domain, the coiled-coil domain of ZAR1 also contributes to resistosome pentamerization by forming an α-helical barrel that interacts with the leucine-rich repeat and winged-helix domains. Structural remodeling and fold switching during activation release the very N-terminal amphipathic α helix of ZAR1 to form a funnel-shaped structure that is required for the plasma membrane association, cell death triggering, and disease resistance, offering clues to the biochemical function of a plant resistosome.
Journal Article
Atomic cobalt as an efficient electrocatalyst in sulfur cathodes for superior room-temperature sodium-sulfur batteries
The low-cost room-temperature sodium-sulfur battery system is arousing extensive interest owing to its promise for large-scale applications. Although significant efforts have been made, resolving low sulfur reaction activity and severe polysulfide dissolution remains challenging. Here, a sulfur host comprised of atomic cobalt-decorated hollow carbon nanospheres is synthesized to enhance sulfur reactivity and to electrocatalytically reduce polysulfide into the final product, sodium sulfide. The constructed sulfur cathode delivers an initial reversible capacity of 1081 mA h g
−1
with 64.7% sulfur utilization rate; significantly, the cell retained a high reversible capacity of 508 mA h g
−1
at 100 mA g
−1
after 600 cycles. An excellent rate capability is achieved with an average capacity of 220.3 mA h g
−1
at the high current density of 5 A g
−1
. Moreover, the electrocatalytic effects of atomic cobalt are clearly evidenced by operando Raman spectroscopy, synchrotron X-ray diffraction, and density functional theory.
Room-temperature sodium-sulfur batteries hold promise, but are hindered by low reversible capacity and fast capacity fade. Here the authors construct a multifunctional sulfur host comprised of cobalt-decorated carbon nanospheres that impart attractive performance as a cathode in a sodium sulfide battery.
Journal Article
A review of the electrical and mechanical properties of carbon nanofiller-reinforced polymer composites
Within decades of development, carbon nanomaterials such as carbon black, fullerene, carbon nanotube, carbon nanofiber, graphene and their combined nanofillers have been tremendously applied in polymer material industries, generating a series of fascinating multifunctional composites in the fields from portable electronic devices, sports, entertainments to automobile, aerospace and military. Among the various material properties of the composites, electrical conductivity and mechanical performance are the two most important parameters for evaluating the effectiveness of nanofillers in the polymer matrices. In this review, we focus on the electrical and mechanical properties of diverse dimensional carbon nanofillers (e.g., zero-, one-, two-, three-dimensional nanofillers or their combinations)-reinforced polymer composites to seek the most efficient and effective approach to obtain high-performance polymeric nanocomposites.
Journal Article
Sulfone-containing covalent organic frameworks for photocatalytic hydrogen evolution from water
Nature uses organic molecules for light harvesting and photosynthesis, but most man-made water splitting catalysts are inorganic semiconductors. Organic photocatalysts, while attractive because of their synthetic tunability, tend to have low quantum efficiencies for water splitting. Here we present a crystalline covalent organic framework (COF) based on a benzo-bis(benzothiophene sulfone) moiety that shows a much higher activity for photochemical hydrogen evolution than its amorphous or semicrystalline counterparts. The COF is stable under long-term visible irradiation and shows steady photochemical hydrogen evolution with a sacrificial electron donor for at least 50 hours. We attribute the high quantum efficiency of fused-sulfone-COF to its crystallinity, its strong visible light absorption, and its wettable, hydrophilic 3.2 nm mesopores. These pores allow the framework to be dye-sensitized, leading to a further 61% enhancement in the hydrogen evolution rate up to 16.3 mmol g−1 h−1. The COF also retained its photocatalytic activity when cast as a thin film onto a support.
Journal Article
Electric load forecasting by complete ensemble empirical mode decomposition adaptive noise and support vector regression with quantum-based dragonfly algorithm
Accurate electric load forecasting can provide critical support to makers of energy policy and managers of power systems. The support vector regression (SVR) model can be hybridized with novel meta-heuristic algorithms not only to identify fluctuations and the nonlinear tendencies of electric loads, but also to generate satisfactory forecasts. However, many such algorithms have numerous drawbacks, such as a low population diversity and trapping at local optima, which are problems of premature convergence. Accordingly, approaches to increase the accuracy of forecasting must be developed. In this investigation, quantum computing mechanism is used to quantamize dragonfly behaviors to enhance the searching effectiveness of the dragonfly algorithm, namely QDA. In addition, conducting the data preprocessing by the complete ensemble empirical mode decomposition adaptive noise (CEEMDAN) is useful to improve the forecasting accuracy. Thus, a new electric load forecasting model, the CEEMDAN-SVRQDA model, that combines the CEEMDAN and hybridizes the QDA with an SVR model, is proposed to provide more accurate forecasts. Two numerical examples from the Tokyo Electric Power Company (Japan) and the National Grid (UK) demonstrate that the proposed model outperforms other models.
Journal Article
Fluorescence umpolung enables light-up sensing of N-acetyltransferases and nerve agents
Intramolecular charge transfer (ICT) is a fundamental mechanism that enables the development of numerous fluorophores and probes for bioimaging and sensing. However, the electron-withdrawing targets (EWTs)-induced fluorescence quenching is a long-standing and unsolved issue in ICT fluorophores, and significantly limits the widespread applicability. Here we report a simple and generalizable structural-modification for completely overturning the intramolecular rotation driving energy, and thus fully reversing the ICT fluorophores’ quenching mode into light-up mode. Specifically, the insertion of an indazole unit into ICT scaffold can fully amplify the intramolecular rotation in donor-indazole-π-acceptor fluorophores (fluorescence OFF), whereas efficiently suppressing the rotation in their EWT-substituted system (fluorescence ON). This molecular strategy is generalizable, yielding a palette of chromophores with fluorescence umpolung that spans visible and near-infrared range. This strategy expands the bio-analytical toolboxes and allows exploiting ICT fluorophores for light-up sensing of EWTs including
N
-acetyltransferases and nerve agents.
The electron-withdrawing target (EWT)-induced fluorescence quenching is an unsolved issue in intramolecular charge transfer (ICT) fluorophores that limits their applicability. Here, the authors report a simple and generalizable strategy to reverse the EWT-induced quenching mode into light-up mode, by introducing an indazole building block between the π-bridge and the donor in the ICT scaffold.
Journal Article
Topology Optimization in Aircraft and Aerospace Structures Design
Topology optimization has become an effective tool for least-weight and performance design, especially in aeronautics and aerospace engineering. The purpose of this paper is to survey recent advances of topology optimization techniques applied in aircraft and aerospace structures design. This paper firstly reviews several existing applications: (1) standard material layout design for airframe structures, (2) layout design of stiffener ribs for aircraft panels, (3) multi-component layout design for aerospace structural systems, (4) multi-fasteners design for assembled aircraft structures. Secondly, potential applications of topology optimization in dynamic responses design, shape preserving design, smart structures design, structural features design and additive manufacturing are introduced to provide a forward-looking perspective.
Journal Article