Matrix metalloproteinase (MMP) is a class of metalloenzyme that cleaves peptide bonds in extracellular matrices. Their functions are important in both health and disease of animals. Here using ...quantum mechanics simulations of the MMP8 protein, the coordination chemistry of different metal cofactors is examined. Structural comparisons reveal that Jhan-Teller effects induced by Cu(II) coordination distorts the wild-type MMP8 active site corresponding to a significant reduction in activity observed in previous experiments. In addition, further analysis suggests that a histidine to glutamine mutation at residue number 197 can potentially allow the MMP8 protein to utilize Cu(II) in reactions. Simulations also demonstrates the requirement of a conformational change in the ligand before enzymatic cleavage. The insights provided here will assist future protein engineering efforts utilizing the MMP8 protein.
Pathogenesis of thrombotic thrombocytopenic purpura (TTP) was a mystery for over half a century until the discovery of ADAMTS13. ADAMTS13 is primarily synthesized in the liver, and its main function ...is to cleave von Willebrand factor (VWF) anchored on the endothelial surface, in circulation, and at the sites of vascular injury. Deficiency of plasma ADAMTS13 activity (<10%) resulting from mutations of the ADAMTS13 gene or autoantibodies against ADAMTS13 causes hereditary or acquired (idiopathic) TTP. ADAMTS13 activity is usually normal or modestly reduced (>20%) in other forms of thrombotic microangiopathy secondary to hematopoietic progenitor cell transplantation, infection, and disseminated malignancy or in hemolytic uremic syndrome. Plasma infusion or exchange remains the initial treatment of choice to date, but novel therapeutics such as recombinant ADAMTS13 and gene therapy are under development. Moreover, ADAMTS13 deficiency has been shown to be a risk factor for the development of myocardial infarction, stroke, cerebral malaria, and preeclampsia.
Lithium sulfur batteries with high energy densities are promising next-generation energy storage systems. However, shuttling and sluggish conversion of polysulfides to solid lithium sulfides limit ...the full utilization of active materials. Physical/chemical confinement is useful for anchoring polysulfides, but not effective for utilizing the blocked intermediates. Here, we employ black phosphorus quantum dots as electrocatalysts to overcome these issues. Both the experimental and theoretical results reveal that black phosphorus quantum dots effectively adsorb and catalyze polysulfide conversion. The activity is attributed to the numerous catalytically active sites on the edges of the quantum dots. In the presence of a small amount of black phosphorus quantum dots, the porous carbon/sulfur cathodes exhibit rapid reaction kinetics and no shuttling of polysulfides, enabling a low capacity fading rate (0.027% per cycle over 1000 cycles) and high areal capacities. Our findings demonstrate application of a metal-free quantum dot catalyst for high energy rechargeable batteries.
In this paper, we present a multimodal emotion recognition framework called EmotionMeter that combines brain waves and eye movements. To increase the feasibility and wearability of EmotionMeter in ...real-world applications, we design a six-electrode placement above the ears to collect electroencephalography (EEG) signals. We combine EEG and eye movements for integrating the internal cognitive states and external subconscious behaviors of users to improve the recognition accuracy of EmotionMeter. The experimental results demonstrate that modality fusion with multimodal deep neural networks can significantly enhance the performance compared with a single modality, and the best mean accuracy of 85.11% is achieved for four emotions (happy, sad, fear, and neutral). We explore the complementary characteristics of EEG and eye movements for their representational capacities and identify that EEG has the advantage of classifying happy emotion, whereas eye movements outperform EEG in recognizing fear emotion. To investigate the stability of EmotionMeter over time, each subject performs the experiments three times on different days. EmotionMeter obtains a mean recognition accuracy of 72.39% across sessions with the six-electrode EEG and eye movement features. These experimental results demonstrate the effectiveness of EmotionMeter within and between sessions.
Co-intercalation reactions make graphite as promising anodes for sodium ion batteries, however, the high redox potentials significantly lower the energy density. Herein, we investigate the factors ...that influence the co-intercalation potential of graphite and find that the tuning of the voltage as large as 0.38 V is achievable by adjusting the relative stability of ternary graphite intercalation compounds and the solvent activity in electrolytes. The feasibility of graphite anode in sodium ion batteries is confirmed in conjunction with Na
VPO
F
cathodes by using the optimal electrolyte. The sodium ion battery delivers an improved voltage of 3.1 V, a high power density of 3863 W kg
, negligible temperature dependency of energy/power densities and an extremely low capacity fading rate of 0.007% per cycle over 1000 cycles, which are among the best thus far reported for sodium ion full cells, making it a competitive choice in large-scale energy storage systems.
Anatase TiO2 is considered as one of the promising anodes for sodium‐ion batteries because of its large sodium storage capacities with potentially low cost. However, the precise reaction mechanisms ...and the interplay between surface properties and electrochemical performance are still not elucidated. Using multimethod analyses, it is herein demonstrated that the TiO2 electrode undergoes amorphization during the first sodiation and the amorphous phase exhibits pseudocapacitive sodium storage behaviors in subsequent cycles. It is also shown that the pseudocapacitive sodium storage performance is sensitive to the nature of solid electrolyte interphase (SEI) layers. For the first time, it is found that ether‐based electrolytes enable the formation of thin (≈2.5 nm) and robust SEI layers, in contrast to the thick (≈10 nm) and growing SEI from conventional carbonate‐based electrolytes. First principle calculations suggest that the higher lowest unoccupied molecular orbital energies of ether solvents/ion complexes are responsible for the difference. TiO2 electrodes in ether‐based electrolyte present an impressive capacity of 192 mAh g−1 at 0.1 A g−1 after 500 cycles, much higher than that in carbonate‐based electrolyte. This work offers the clarified picture of electrochemical sodiation mechanisms of anatase TiO2 and guides on strategies about interfacial control for high performance anodes.
A thin and robust solid electrolyte interphase formed on a TiO2 surface that is enabled by using ether electrodes is demonstrated in Na‐ion batteries. This electrolyte/electrolyte interface, which is superior to conventional carbonate electrolyte, results in largely different electrochemical performances. The fundamental origin of the difference is unveiled through the combination of intensive experimental characterizations and first principles calculations.
Calcium ion batteries (CIBs) are pursued as potentially low‐cost and safe alternatives to current Li‐ion batteries due to the high abundance of calcium element. However, the large and divalent nature ...of Ca2+ leads to strong interaction with intercalation hosts, sluggish ion diffusion kinetics and low power output. Herein, a small molecular organic anode is reported, tetracarboxylic diimide (PTCDI), involving carbonyl enolization (CO↔CO−) in aqueous electrolytes, which bypasses the diffusion difficulties in intercalation‐type electrodes and avoid capacity sacrifice for polymer organic electrodes, thus manifesting rapid and high Ca storage capacities. In an aqueous Ca‐ion cell, the PTCDI presents a reversible capacity of 112 mAh g−1, a high‐capacity retention of 80% after 1000 cycles and a high‐power capability at 5 A g−1, which rival the state‐of‐the‐art anode materials in CIBs. Experiments and simulations reveal that Ca ions are diffusing along the a axis tunnel to enolize carbonyl groups without being entrapped in the aromatic carbon layers. The feasibility of PTCDI anodes in practical CIBs is demonstrated by coupling with cost‐effective Prussian blue analogous cathodes and CaCl2 aqueous electrolyte. The appreciable Ca storage performance of small molecular crystals will spur the development of green organic CIBs.
PTCDI is first employed as the anode for aqueous calcium‐ion batteries. The guest‐host chemical bonding and structure evolution of molecular crystals are clearly clarified by simulation and in(ex)‐situ spectroscopy characterizations. This study extends the boundary of molecular crystal systems for electrochemistry to construct high‐performance aqueous multivalent ion batteries.
Ca‐ion batteries (CIBs) have been considered a promising candidate for the next‐generation energy storage technology owing to the abundant calcium element and the low reduction potential of Ca2+/Ca. ...However, the large size and divalent nature of Ca2+ induce significant volume change and sluggish ion mobility in intercalation cathodes, leading to poor reversibly and low energy/power densities for CIBs. Herein, a polyanionic Na superionic conduction (NASICON)‐typed Na‐vacant Na1V2(PO4)2F3 (N1PVF3) with sufficient interstitial spaces is reported as ultra‐stable and high‐energy Ca ion cathodes. The N1PVF3 delivers exceptionally high Ca storage capacities of 110 and 65 mAh g‐1 at 10 and 500 mA g–1, respectively, and a record‐long cyclability of 2000 cycles. More interestingly, by tailoring the fluorine content in N1PVFx (1 ≤ x ≤ 3), the high working potential of 3.5 V versus Ca2+/Ca is achievable. In conjunction with Ca metal anode and a compatible electrolyte, Ca metal batteries with N1VPF3 cathodes are constructed, which deliver an initial energy density of 342 W h kg‐1, representing one of the highest values thus far reported for CIBs. Origins of the uncommonly stable and high‐power capabilities for N1PVF3 are elucidated as the small volume changes and low cation diffusion barriers among the cathodes.
The merits of covalent open framework with large tunnel sites, substantial Na interstitial vacancies, and fluorine‐rich phase indicate Na1V2(PO4)2F3 (N1VPF3) as an excellent candidate for Ca ion storage with high redox potentials. As a proof of concept, the N1VPF3 cathode demonstrates exceptionally high energy density and long‐term cyclic stability in Ca ion batteries.
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•The fundamentals of LSBs, carbon nanomaterials and sulfur/carbon cathodes are discussed.•Design principles of nanocarbon to overcome the intrinsic challenges of LSBs are ...summarized.•The gap between the current achievements and the practical LSBs in real-market is bridged.
Taking advantage of a high theoretical energy density of 2567 Wh kg-1, lithium sulfur batteries (LSBs) have been considered promising candidates for next-generation energy storage systems. Nevertheless, challenging issues involving both sulfur cathode and lithium anode hinder their practical applications, which are followed by the extensive research efforts to resolve them. A wide variety of carbon nanomaterials with different characteristics has played an important role in enhancing the performance of LSBs via immobilizing sulfur in cathodes, accommodating the volume expansion of sulfur, enhancing the reaction kinetics and stabilizing lithium anodes. This report overviews the state-of-the-art progress in designing and fabricating nanocarbon for advanced LSBs with particular focuses on the correlations among porosity, electrical conductivity and surface chemistry as some of the most critical factors. More importantly, statistical analysis of electrochemical performance of batteries collected from literatures allows us to identify substantial disparities between the current achievements and the requirements for real-world applications. In an effort to bridge this gap, we highlight recent advances in the design of LSBs with improved sulfur loading, enhanced charge transfer and minimized electrolyte/sulfur ratio. Conclusions and perspectives for future development of nanocarbon in LSBs are proposed.
While esters are frequently used as traditional electrophiles in substitution chemistry, their application in cross‐coupling chemistry is still in its infancy. This work demonstrates that methyl ...esters can be used as coupling electrophiles in Ni‐catalyzed Heck‐type reactions through the challenging cleavage of the C(acyl)−O bond under relatively mild reaction conditions at either 80 or 100 °C. With the σ‐NiII intermediate generated from the insertion of acyl NiII species into the tethered C=C bond, carbonyl‐retentive products were formed by domino Heck/Suzuki–Miyaura coupling and Heck/reduction pathways when organoboron and mild hydride nucleophiles are used.
Partner up: Methyl esters are shown to be viable cross‐coupling partners in intramolecular cyclization reactions with a tethered olefin. Both a boronic acid and mild hydride donors can be used in this nickel‐catalyzed reaction, providing differentially substituted indanone products.
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