To conquer the bottleneck of sluggish kinetics in cathodic oxygen reduction reaction (ORR) of metal‐air batteries, catalysts with dual‐active centers have stood out. Here, a “pre‐division metal ...clusters” strategy is firstly conceived to fabricate a N,S‐dual doped honeycomb‐like carbon matrix inlaid with CoN4 sites and wrapped Co2P nanoclusters as dual‐active centers (Co2P/CoN4@NSC‐500). A crystalline {CoII2} coordination cluster divided by periphery second organic layers is well‐designed to realize delocalized dispersion before calcination. The optimal Co2P/CoN4@NSC‐500 executes excellent 4e− ORR activity surpassing the benchmark Pt/C. Theoretical calculation results reveal that the CoN4 sites and Co2P nanoclusters can synergistically quicken the formation of *OOH on Co sites. The rechargeable Zn‐air battery (ZAB) assembled by Co2P/CoN4@NSC‐500 delivers ultralong cycling stability over 1742 hours (3484 cycles) under 5 mA cm−2 and can light up a 2.4 V LED bulb for ≈264 hours, evidencing the promising practical application potentials in portable devices.
A “pre‐division metal clusters” strategy is first conceived to fabricate dual‐active center catalysts (Co2P/CoN4@NSC‐500) with dispersed CoN4 and Co2P sites. The optimal catalyst executes superior ORR activity and was applied in ultralong Zn‐air batteries surpassing the benchmark 20 % Pt/C. Theoretical calculations demonstrate that the dual‐active sites synergistically quicken the formation of the *OOH intermediate, greatly boosting the performance.
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The resonance assisted hydrogen bond (RAHB) is a special type of hydrogen bonding (HB). With the influence of the π-electron delocalization, the RAHB is stronger than normal HB which is solely based ...on an electrostatic interaction. The carbamate functionalized thiophene-thiazolothiazole-thiophene (CTZ) has been synthesized as a building block for semiconducting polymers. The introduction of the carbamate side chains to thiophene-thiazolothiazole-thiophene (TTZ) provided solubility, enabled RAHB interactions, and enhanced polarity. Single-crystal X-ray diffraction analysis revealed that the RAHB interactions facilitated the coplanarity of CTZ and the close π-contacts between neighboring molecules in the solid state. The CTZ in single crystals adopted a lamellar packing instead of slipped herringbone stacking which was found in single crystals of previously reported TTZs. Two new π-conjugated polymers, PCTZ-T and PCTZ-B, based on CTZ have also been synthesized. The OFET devices based on PCTZ-T showed an average hole mobility of 1.98 cm2 V–1 s–1, threshold voltages of −2.1 to −5.7 V, and ON/OFF current ratios of 106–107. Bulk heterojunction organic photovoltaic devices with PCTZ-B as the donor and Y6 as small molecular nonfullerene acceptors achieved a power conversion efficiency of 12.7%. The results have demonstrated that RAHB is an effective strategy for designing high-performance organic semiconducting polymers.
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•The MoSx/CdS was first controllably and accurately synthesized by using a facile approach.•The MoSx/CdS exhibits H2 evolution rate of 22.5 mmol g−1 h−1.•The place of heterostructure ...construction matches well with that of electrons extracted.•The high performance can be attributed to the well-defined interfaces formation.
Exploration of low-cost and earth-abundant photocatalysts for efficient photocatalytic H2 evolution from water is an attractive solution to the global energy and environmental problems. Although MoS2 has been proved as an efficient co-catalyst for the H2 evolution reaction (HER), controllably and accurately constructing MoS2-hybridized photocatalysts at where the electrons extracted still remains a challenge. Here, a facile two-step approach of photoetching-photodeposition has been developed to prepare MoSx/etched-CdS (Mo-Cd(e)-S) with heterostructure accurately constructed on the CdS surface defects. This structure can significantly accelerate photo-induced charge separation and transportation owing to the place of heterostructure construction matching well with that of electrons extracted, numerous active sites introduced, and shorter charge transfer path from bulk to surface. Therefore the charge recombination is significantly retarded. As a result, the Mo-Cd(e)-S exhibits outstanding photocatalytic performance with a state-of-the-art H2 generation rate of 22.5 mmol g−1 h−1 under visible light irradiation (λ ≥ 420 nm) which is 70 times higher than that of pristine CdS. This work opens a new avenue for the low-cost but high efficient photocatalysts development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Immune recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors often activates proinflammatory NF-κB signalling
. Recent studies indicate that the bacterial ...metabolite D-glycero-β-D-manno-heptose 1,7-bisphosphate (HBP) can activate NF-κB signalling in host cytosol
, but it is unclear whether HBP is a genuine PAMP and the cognate pattern recognition receptor has not been identified. Here we combined a transposon screen in Yersinia pseudotuberculosis with biochemical analyses and identified ADP-β-D-manno-heptose (ADP-Hep), which mediates type III secretion system-dependent NF-κB activation and cytokine expression. ADP-Hep, but not other heptose metabolites, could enter host cytosol to activate NF-κB. A CRISPR-Cas9 screen showed that activation of NF-κB by ADP-Hep involves an ALPK1 (alpha-kinase 1)-TIFA (TRAF-interacting protein with forkhead-associated domain) axis. ADP-Hep directly binds the N-terminal domain of ALPK1, stimulating its kinase domain to phosphorylate and activate TIFA. The crystal structure of the N-terminal domain of ALPK1 and ADP-Hep in complex revealed the atomic mechanism of this ligand-receptor recognition process. HBP was transformed by host adenylyltransferases into ADP-heptose 7-P, which could activate ALPK1 to a lesser extent than ADP-Hep. ADP-Hep (but not HBP) alone or during bacterial infection induced Alpk1-dependent inflammation in mice. Our findings identify ALPK1 and ADP-Hep as a pattern recognition receptor and an effective immunomodulator, respectively.
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The construction of an efficient oxygen reduction reaction and oxygen evolution reaction (ORR/OER) bifunctional electrocatalyst is of great significance but still remains a giant challenge for ...high-performance metal–air batteries. In this study, uniform FeS/Fe3C nanoparticles embedded in a porous N,S-dual doped carbon honeycomb-like composite (abbr. FeS/Fe3C@NS-C-900) have been conveniently fabricated by pyrolysis of a single-crystal Fe-MOF, which has a low potential gap ΔE of ca. 0.72 V, a competitive power density of 90.9 mW/cm2, a specific capacity as high as 750 mAh/g Zn , and excellent cycling stabilities over 865 h (1730 cycles) at 2 mA/cm2 when applied as a cathode material for rechargeable zinc–air batteries. In addition, the two series-linked Zn–air batteries successfully powered a 2.4 V LED light as a real power source. The efficient ORR/OER bifunctional electrocatalytic activity and long-term durability of the obtained composite might be attributed to the characteristic honeycomb-like porous structure with sufficient accessible active sites, the synergistic effect of FeS and Fe3C, and the N,S codoped porous carbon, which provides a promising application potential for portable electronic Zn–air battery related devices.
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Summary
Transmembrane chemoreceptors are widely present in Bacteria and Archaea. They play a critical role in sensing various signals outside and transmitting to the cell interior. Here, we report ...the structure of the periplasmic ligand‐binding domain (LBD) of the transmembrane chemoreceptor MCP2201, which governs chemotaxis to citrate and other organic compounds in Comamonas testosteroni. The apo‐form LBD crystal revealed a typical four‐helix bundle homodimer, similar to previously well‐studied chemoreceptors such as Tar and Tsr of Escherichia coli. However, the citrate‐bound LBD revealed a four‐helix bundle homotrimer that had not been observed in bacterial chemoreceptor LBDs. This homotrimer was further confirmed with size‐exclusion chromatography, analytical ultracentrifugation and cross‐linking experiments. The physiological importance of the homotrimer for chemotaxis was demonstrated with site‐directed mutations of key amino acid residues in C. testosteroni mutants.
The structure of chemoreceptor MCP2201 LBD was solved. The apo‐form (ligand‐free) of MCP2201 LBD is a 4HB homodimer. In the presence of ligand citric acid, a previously unknown trimeric structure of MCP2201 LBD was observed. These results raised the possibility that ligand‐binding induced oligomer‐organization dynamics and subsequently signal generation within chemoreceptors.
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A new family of 2D coordination polymers based on 3d‐4f 15‐metallacrown‐5 (MC) units were designed and characterized. The connection of the 15‐metallacrown‐5 subunits by the coordination of CuII and ...ligand led to the formation of 2D network of metallacrowns. Analysis of the magnetic properties of these coordination polymers reveals that the GdIII (1), TbIII (2), and DyIII (3) complexes exhibit slow magnetic relaxation and under 1000 Oe dc field, and the DyIII (3) complex exhibits single‐molecule magnet behavior.
A new family of 2D coordination polymers based on 3d‐4f 15‐metallacrown‐5 (MC) units was designed and characterized. The connection of the 15‐metallacrown‐5 subunits by the coordination of CuII and ligand led to the formation of 2D network of metallacrowns. The GdIII, TbIII, and DyIII complexes exhibit slow magnetic relaxation, and the DyIII complex is a single‐molecule magnet under 1000 Oe dc field.
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The concept of the OOS of spacecraft can be traced back to the 1960s, when the main focus was on providing the necessary maintenance to advance the lifetime of spacecraft and extending the scale and ...function through on-orbit assembly. During the past decades, the Hubble Space Telescope has made great contributions to the fields of astronomy and physics through both observational data and the success of five OOS missions to overcome big challenges. That included an initial flaw of its primary mirror and subsequent obstacles associated with replacing and upgrading its science instruments. Furthermore, many programs have been carried out in the area of the OOS of spacecraft with successful operations in space. It could be exemplified by the assembly of the International Space Station, service verification of ETS-VII and Orbital Express, and detailed research for future applications including servicer and client satellites and particularly large space systems. This paper attempts to summarize all reported programs of the OOS in terms of engineering developments and provide an overall perspective for investigators in this field. Based on the reviewed programs, an analysis is carried out to elucidate the logical architectures of the mission and technology of the OOS of spacecraft. Further attention is paid to discussions of the enabling technologies that support the development of the OOS and related spacecraft. As an outlook, the future development and challenges of the OOS and the application of novel technologies are finally discussed to extend the present review work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this work, we analyze the three-body B ( s ) → η c ( 1 S , 2 S ) K π decays within the framework of the perturbative QCD approach (PQCD) under the quasi-two-body approximation, where the kaon-pion ...invariant mass spectra are dominated by the K ∗ 0 ( 1430 ) 0 , K ∗ 0 ( 1950 ) 0 , K ∗ ( 892 ) 0 , K ∗ ( 1410 ) 0 , K ∗ ( 1680 ) 0 , and K ∗ 2 ( 1430 ) 0 resonances. The time-like form factors are adopted to parametrize the corresponding S , P , D -wave kaon-pion distribution amplitudes for the concerned decay modes, which describe the final-state interactions between the kaon and pion in the resonant region. The K π S -wave component at low K π mass is described by the LASS line shape, while the time-like form factors of other resonances are modeled by the relativistic Breit-Wigner function. We find the following main points: (a) the PQCD predictions of the branching ratios for most considered B → η c ( 1 S ) ( K * 0 → ) K + π − decays agree well with the currently available data within errors; (b) for B ( B 0 → η c ( K ∗ 0 ( 1430 ) → ) K + π − ) and B ( B 0 → η c K + π − ( NR ) ) (where NR means nonresonant), our predictions of the branching ratios are a bit smaller than the measured ones; and (c) the PQCD results for the D -wave contributions considered in this work can be tested once precise data from the future LHCb and Belle-II experiments become available.
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Zn–iodine (I2) battery, as a promising energy storage device, especially under high I2 loading, is harassed by the shuttle effect of the soluble polyiodide intermediates. Herein, the bifunctional ...role of 2D carbon nanosponge with rich P‐dopant (4.2 at%) and large specific surface area (1966 m2 g−1) in anchoring I2/Ix− (x = 1, 3 or 5) and catalyzing their mutual conversion is reported. Both experiment and computational results reveal the transfer of electrons from the P‐doped site to iodine species, showing strong interfacial interaction. When being used as a host, it possesses high specific capture capacity for I2 (3.34 giodine g−1 or 1.6 mgiodine m−2) and Ix− (6.12 gtriiodide g−1 or 3.1 mgtriiodide m−2), which thus effectively suppresses the shuttle effect, supported by in situ UV–vis and Raman spectra. In addition to the strong interfacial interaction that favors iodine conversion, the P‐doped sites can also catalyze the conversion of I5− to I2, which is the rate‐determining step. Consequently, Zn–I2 batteries under a high I2 content (70 wt%) deliver high specific capacity (220.3 mAh g−1), superior Coulombic efficiency (>99%), and low self‐discharge rate; moreover, they can also operate steadily at 2 A g−1 with ignorable capacity decay for 10 000 cycles.
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