Designing artificial nitrogen fixing devices with functions of light energy adsorption and driven nitrogen species upgrade and oxygen evolution is highly attractive. However, advanced catalytic ...materials for key NO3‐‐to‐NH4+ and OH‐‐to‐O2 reactions are rather rare. Herein, first principle calculations are performed to pre‐screen target catalysts and then the effective catalyst in the experiment is successfully prepared, with which, a high power density Zn‐nitrate electrochemical cell is demonstrated. The cathode catalyst can promote both reductive NO3‐‐to‐NH4+ and oxidative OH‐‐to‐O2 reactions in low‐overpotential pathways, contributing to the total battery reaction: NO3‐ + 3H2O → NH4+ + 2OH‐ + 2O2. The resulting electrochemical cell shows over 90% NO3‐‐to‐NH4+ selectivity, a high power density over 25 mW cm‐2, and stable 35 h cycling at 12.5 mA cm‐2. Moreover, this Zn‐nitrate electrochemical cell can work driven by the photovoltaic cell with the solar‐to‐NH3 efficiency up to 19.5%. This study demonstrates a theoretically screened catalyst realizing a photovoltaic driven high‐rate Zn‐nitrate electrochemical cell system, which mimics soybean system upgrading N species and producing oxygen.
Mimicking nitrogen fixing plants that absorb light, upgrade nitrogen species, and produce oxygen, a photovoltaic‐driven high‐power‐density aqueous Zn‐nitrate electrochemical cell is realized based on the theoretical‐screen bifunctional catalyst cathode for low‐overpotential nitrate‐to‐ammonia and water‐to‐oxygen reactions. The resulting device operates under the total battery reaction: NO3– + 3H2O → NH4+ + 2OH– + 2O2, and achieves the maximum 19.5% solar‐to‐ammonia efficiency.
Dearomatization of anthranils with vinylcyclopropanes (VCPs) by Pd‐catalyzed 4+3 cyclization reaction has been realized. In the presence of a catalytic amount of borane as an activator, bridged ...cyclic products were obtained in good to excellent yields with excellent stereoselectivities. By introducing a chiral PHOX ligand (L5), asymmetric dearomatization reactions of anthranils with vinylcyclopropanes proceeded with excellent enantioselectivity. Borane plays a key role for the reactivity, likely owing to the formation of a borane–anthranil complex which has been confirmed by NMR experiments.
Dearomatization of anthranils with vinylcyclopropanes (VCPs) by Pd‐catalyzed 4+3 cyclization reaction has been realized. In the presence of a catalytic amount of borane as an activator, bridged cyclic products were obtained in good to excellent yields with excellent stereoselectivities. By introducing a chiral PHOX ligand, asymmetric dearomatization reactions of anthranils with vinylcyclopropanes proceeded with excellent enantioselectivity.
Heck reaction is one of the most important carbon‐carbon bond forming reactions with wide applications in organic synthesis. Considerable advances of enantioselective Heck reaction have been achieved ...in the past decades. This review focuses on recent development of catalytic asymmetric Heck reaction and reductive Heck reaction, which covers intermolecular and intramolecular versions since 2011. The article is organized in terms of the catalysts and olefin substrates.
Recent progress of catalytic asymmetric Heck reactions and reductive Heck reactions since 2011 is described.
Picture book creation has a rich metaphorical connotation, which is becoming more and more popular along with the development of digitalization. In this paper, the textual metaphors of picture book ...creation are extracted by combining the textual feature extraction model of the BERT pre-training model and HAN network, the ResNet50 network extracts the illustration metaphors of picture book creation, and the extracted metaphorical features are multimodal fused and recognized with the help of fully connected layer. In addition, a picture book metaphor dataset was constructed, and after analyzing the basic features of picture book metaphors, the effect of the constructed multimodal metaphor recognition was explored, and the recognition and communication of metaphors in picture book creation was studied. The results showed that the recognition accuracy in picture book creation ranged from 0.67 to 0.77, and the high degree of metaphor recognition in picture book creation showed a positive correlation with the average response time of communication, with the regression equation RT=138.45*IdentificationStd+1045.The results of the analysis of the metaphorical picture book creation pictures with textual references showed that the degree of communication comprehension (M=22.38. Std.=3.68), communication liking (M=94.86, Std.=13.58) and reaction time (M=82.44s, Std.=14.15s). Picture books facilitate better interactive communication through their metaphorical expression.
A large number of SARS-related coronaviruses (SARSr-CoV) have been detected in horseshoe bats since 2005 in different areas of China. However, these bat SARSr-CoVs show sequence differences from SARS ...coronavirus (SARS-CoV) in different genes (S, ORF8, ORF3, etc) and are considered unlikely to represent the direct progenitor of SARS-CoV. Herein, we report the findings of our 5-year surveillance of SARSr-CoVs in a cave inhabited by multiple species of horseshoe bats in Yunnan Province, China. The full-length genomes of 11 newly discovered SARSr-CoV strains, together with our previous findings, reveals that the SARSr-CoVs circulating in this single location are highly diverse in the S gene, ORF3 and ORF8. Importantly, strains with high genetic similarity to SARS-CoV in the hypervariable N-terminal domain (NTD) and receptor-binding domain (RBD) of the S1 gene, the ORF3 and ORF8 region, respectively, were all discovered in this cave. In addition, we report the first discovery of bat SARSr-CoVs highly similar to human SARS-CoV in ORF3b and in the split ORF8a and 8b. Moreover, SARSr-CoV strains from this cave were more closely related to SARS-CoV in the non-structural protein genes ORF1a and 1b compared with those detected elsewhere. Recombination analysis shows evidence of frequent recombination events within the S gene and around the ORF8 between these SARSr-CoVs. We hypothesize that the direct progenitor of SARS-CoV may have originated after sequential recombination events between the precursors of these SARSr-CoVs. Cell entry studies demonstrated that three newly identified SARSr-CoVs with different S protein sequences are all able to use human ACE2 as the receptor, further exhibiting the close relationship between strains in this cave and SARS-CoV. This work provides new insights into the origin and evolution of SARS-CoV and highlights the necessity of preparedness for future emergence of SARS-like diseases.
Herein we report a catalytic asymmetric dearomatization reaction of electron‐deficient heteroarenes with α‐substituted isocyanoacetates through an interrupted Barton–Zard reaction. A range of ...optically active pyrrolo3,4‐bindole derivatives was obtained in good yields (up to 97 %) with high stereoselectivities (up to >20:1 dr and 97 % ee), using a catalytic system consisting of a cinchona‐derived amino‐phosphine and silver oxide. This reaction features wide substrate scope and mild conditions, and provides a new strategy for developing asymmetric dearomatization reactions.
Catalytic asymmetric dearomatization reaction of electron‐deficient heteroarenes with α‐substituted isocyanoacetate ester through an interrupted Barton–Zard reaction is reported. A range of optically active pyrrolo3,4‐bindole derivatives was obtained in good reactivity (up to 99 % yield) with high stereoselectivities (up to >20:1 dr, 97 % ee) in the presence of 2.5 mol % Ag2O and amino‐phosphine L1.
Herein we report a Pd‐catalyzed dearomative methoxyallylation of 3‐nitroindoles with readily available allyl carbonates. Good yields (up to 86 %) and diastereoselectivity (up to >20:1 dr) are ...obtained for a wide range of substrates. The compatibility of gram‐scale synthesis and the relatively low catalyst loading (down to 1 mol % of Pd) enhance the practicality of this method. The kinetic experiments indicate that the rate‐determining step of this reaction is the nucleophilic attack of the alkoxide anion.
An intermolecular Pd‐catalyzed dearomative methoxyallylation of 3‐nitroindoles with readily available allyl carbonates was reported. Good yields (up to 86 %) and diastereoselectivity (up to >20:1 dr) are obtained for a wide range of substrates. The compatibility of gram‐scale synthesis and the relatively low catalyst loading (down to 1 mol % of Pd) enhance the practicality of this method.
Sulfurized polyacrylonitrile is suggested to contain S
(n ≤ 4) and shows good electrochemical performance in carbonate electrolytes for lithium sulfur batteries. However inferior results in ether ...electrolytes suggest that high solubility of Li
S
(n ≤ 4) trumps the limited redox conversion, leading to dissolution and shuttling. Here, we introduce a small amount of selenium in sulfurized polyacrylonitrile to accelerate the redox conversion, delivering excellent performance in both carbonate and ether electrolytes, including high reversible capacity (1300 mA h g
at 0.2 A g
), 84% active material utilization and high rate (capacity up to 900 mA h g
at 10 A g
). These cathodes can undergo 800 cycles with nearly 100% Coulombic efficiency and ultralow 0.029% capacity decay per cycle. Polysulfide dissolution is successfully suppressed by enhanced reaction kinetics. This work demonstrates an ether compatible sulfur cathode involving intermediate Li
S
(n ≤ 4), attractive rate and cycling performance, and a promising solution towards applicable lithium-sulfur batteries.
A novel and unusual palladium‐catalyzed 4+2 annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si−C(sp2) bond activation in synergy with ...ring expansion/insertion of cyclopropenes to form new C(sp2)−C(sp3) and Si−C(sp3) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo4.1.0heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles.
When Si−C meets C=C bond activation: Cyclopropenes were functionalized stereoselectively with benzosilacyclobutanes by palladium‐catalyzed Si−C(sp2) bond activation and a ring‐expansion/4+2 annulation sequence to form new C(sp2)−C(sp3) and Si−C(sp3) bonds of silabicyclo4.1.0heptanes. The transformation provided an array of these previously elusive highly strained bicyclic skeletons in good yields with high selectivity (see scheme).
Solar steam generation with subsequent steam recondensation has been regarded as one of the most promising techniques to utilize the abundant solar energy and sea water or other unpurified water ...through water purification, desalination, and distillation. Although tremendous efforts have been dedicated to developing high‐efficiency solar steam generation devices, challenges remain in terms of the relatively low efficiency, complicated fabrications, high cost, and inability to scale up. Here, inspired by the water transpiration behavior of trees, the use of carbon nanotube (CNT)‐modified flexible wood membrane (F‐Wood/CNTs) is demonstrated as a flexible, portable, recyclable, and efficient solar steam generation device for low‐cost and scalable solar steam generation applications. Benefitting from the unique structural merits of the F‐Wood/CNTs membrane—a black CNT‐coated hair‐like surface with excellent light absorbability, wood matrix with low thermal conductivity, hierarchical micro‐ and nanochannels for water pumping and escaping, solar steam generation device based on the F‐Wood/CNTs membrane demonstrates a high efficiency of 81% at 10 kW cm−2, representing one of the highest values ever‐reported. The nature‐inspired design concept in this study is straightforward and easily scalable, representing one of the most promising solutions for renewable and portable solar energy generation and other related phase‐change applications.
A nature‐inspired steam‐generation materialof flexible wood/CNTs composite membrane is developed directly from natural wood. Systematic optimizations of water transportation, thermal management, and light absorption and thus high water evaporating efficiency can be realized by using the nature‐made channels in wood for efficient water transportation, intrinsic thermal‐insolating wood matrix as thermal barrier, and CNT‐coated surface as light absorber.
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