Polybenzimidazoles are engineering plastics with superb thermal stability and this specificity has sparked a wide‐ranging research to explore proton‐conducting materials. Nevertheless, such materials ...encounter challenging issues owing to phosphoric acid proton carrier leakage and slow proton transport. We report a strategy for designing porous polybenzimidazole frameworks to address these key fundamental issues. The built‐in channels are designed to be one‐dimensionally extended, unidirectionally aligned, and fully occupied by neat phosphoric acid, while the benzimidazole walls trigger multipoint, multichain, and multitype interactions to spatially confine a phosphoric acid network in pores and facilitate proton conduction via deprotonation. The materials exhibit ultrafast and stable proton conduction for low proton carrier content and activation energy—a set of features highly desired for proton transport. Our results offer a design strategy for the fabrication of porous polybenzimidazoles for use in energy conversion applications.
Condensing benzimidazole units via topology‐directed polymerization allows the construction of stable covalent organic frameworks with ordered one‐dimensional channels. The walls trigger multiple hierarchical interactions so that the proton networks are locked in the pores via spatial confinement and activated via deprotonation. Ultrafast and stable anhydrous proton conduction is achieved over a wide range of temperatures.
Density functional theory calculations were performed to investigate the copper-catalyzed borocyanation of 2-aryl-substituted 1,3-dienes. The computations show that the regioselectivity of the ...overall reaction is governed by the combination of the inherent regioselectivity of the borocupration and electrophilic cyanation steps. The π-conjugation effect of the 1,3-diene makes the terminal carbon atoms more electrophilic compared with the internal carbon atoms, which coupled with the steric effect results in the 4,3- and 1,2-borocupration being intrinsically more favorable than the other possibilities. The steric repulsion around the breaking Cu–C bond was found to be the key factor in determining the regioselectivity of the electrophilic cyanation. The origins of the experimentally observed ligand-controlled regioselectivity were ascribed to the electronic and steric effects. For the bulky XantPhos ligand, the 4,3-borocupration was found to be more favorable than the 1,2-borocupration due to the steric repulsion around the forming Cu–C bond, resulting in the formation of the 4,3-borocyantion product. On the other hand, the reversed regioselectivity with a small PCy3 ligand is mainly caused by the electronic effect that the π-electron-withdrawing aryl group at the C2 atom makes the C1 atom more electrophilic than the C4 atom, enabling the 1,2-borocupration to be more favorable than the 4,3-borocupration.
Atomically thin materials (ATMs) with thicknesses in the atomic scale (typically <5 nm) offer inherent advantages of large specific surface areas, proper crystal lattice distortion, abundant surface ...dangling bonds, and strong in-plane chemical bonds, making them ideal 2D platforms to construct high-performance electrode materials for rechargeable metal-ion batteries, metal-sulfur batteries, and metal-air batteries. This work reviews the synthesis and electronic property tuning of state-of-the-art ATMs, including graphene and graphene derivatives (GE/GO/rGO), graphitic carbon nitride (g-C3N4), phosphorene, covalent organic frameworks (COFs), layered transition metal dichalcogenides (TMDs), transition metal carbides, carbonitrides, and nitrides (MXenes), transition metal oxides (TMOs), and metal-organic frameworks (MOFs) for constructing next-generation high-energy-density and high-power-density rechargeable batteries to meet the needs of the rapid developments in portable electronics, electric vehicles, and smart electricity grids. We also present our viewpoints on future challenges and opportunities of constructing efficient ATMs for next-generation rechargeable batteries.
Abstract MALAT1 is an oncogenic long non-coding RNA that has been found to promote the proliferation of many malignant cell types and non-malignant human umbilical vein endothelial cells (HUVECs). ...However, the functions of MALAT1 in vasculogenic mimicry (VM) and angiogenesis and the potential mechanisms responsible have not yet been investigated in any malignancy. Here, in situ hybridization and CD31/periodic acid-Schiff double staining of 150 gastric cancer (GC) clinical specimens revealed that MALAT1 expression was tightly associated with densities of VM and endothelial vessels. MALAT1 knockdown markedly reduced GC cell migration, invasion, tumorigenicity, metastasis, and VM, while restricting HUVEC angiogenesis and increasing vascular permeability. Moreover, MALAT1 was found to regulate expression of VE-cadherin, β-catenin, MMPs 2 and 9, MT1-MMP, p-ERK, p-FAK, and p-paxillin, which have been established as classical markers of VM and angiogenesis and components of associated signaling pathways. Consistent with this, the p-ERK inhibitors U0126 and PD98059 both effectively blocked GC cell VM. In conclusion, MALAT1 can promote tumorigenicity and metastasis in GC by facilitating VM and angiogenesis via the VE-cadherin/β-catenin complex and ERK/MMP and FAK/paxillin signaling pathways.
Searching new organic cathode materials to address the issues of poor cycle stability and low capacity in lithium ion batteries (LIBs) is very important and highly desirable. In this research, a 2D ...boroxine‐linked chemically‐active pyrene‐4,5,9,10‐tetraone (PTO) covalent organic framework (2D PPTODB COFs) was synthesized as an organic cathode material with remarkable electrochemical properties, including high electrochemical activity (four redox electrons), safe oxidation potential window (between 2.3 and 3.08 V vs. Li/Li+), superb structural/chemical stability, and strong adhesiveness. A binder‐free cathode was obtained by mixing 70 wt % PPTODB and 30 wt % carbon nanotubes (CNTs) as a conductive additive. Promoted by the fast kinetics of electrons/ions, high electrochemical activity, and effective π–π interaction between PPTODB and CNTs, LIBs with the as‐prepared cathode exhibited excellent electrochemical performance: a high specific capacity of 198 mAh g−1, a superb rate ability (the capacity at 1000 mA g−1 can reach 76 % of the corresponding value at 100 mA g−1), and a stable coulombic efficiency (≈99.6 % at the 150th cycle). This work suggests that the concept of binder‐free 2D electroactive materials could be a promising strategy to approach energy storage with high energy density.
COF‐based cathodes: A 2D covalent organic framework (2D PPTODB COFs) containing boroxine units and chemically active pyrene‐4,5,9,10‐tetraone (PTO) species is synthesized and shows high electrochemical activity, safe oxidation potential, and superb structural/chemical stability. The binder‐free cathode exhibits a high specific capacity, superb rate ability, and stable coulombic efficiency.
A recently reported palladium‐catalyzed allylic substitution of vinyl‐substituted cyclic carbonates (VCCs) with aryl amines represents a rare example of a regio‐ and enantioselective synthesis of ...α,α‐disubstituted allylic N‐aryl amines. However, the underlying reasons for this unusual selectivity profile remain elusive. In the present work, density functional theory (DFT) calculations in combination with mechanistic control experiments were performed to elucidate in detail this allylic amination manifold and the origin of the regio‐ and enantioselectivity. The combined data show that after oxidative addition of the VCC to Pd0, the nucleophilic attack via an originally proposed outer‐sphere pathway gives, however, the opposite regioisomer compared to the experimental results. Instead, nucleophilic attack of the amine reagent via a unique type of chelation‐assisted, inner‐sphere pathway accounts for the experimentally observed “branched” regioselectivity and high enantio‐control.
A unique chelation‐assisted, inner‐sphere pathway for the Pd‐catalyzed allylic amination of vinyl cyclic carbonates with aryl amines was revealed by DFT calculations and various experiments. A chelation effect enabled through a η2‐coordination of the N‐aryl group to the Pd centre was identified as a key interaction with profound implication for the selectivity parameters.
The persistence of cholesterol-engorged macrophages （foam cells） in the artery wall fuels the development of atherosclerosis. However, the mechanism that regulates the formation of macrophage foam ...cells and impedes their emigration out of inflamed plaques is still elusive. Here, we report that adhesion receptor CD146 controls the formation of macrophage foam cells and their retention within the plaque during atherosclerosis exacerbation. CD146 is expressed on the macrophages in human and mouse atheroma and can be upregulated by oxidized low-density lipo- protein （oxLDL）. CD146 triggers macrophage activation by driving the internalization of scavenger receptor CD36 during lipid uptake. In response to oxLDL, macrophages show reduced migratory capacity toward chemokines CCL19 and CCL21; this capacity can be restored by blocking CD146. Genetic deletion of macrophagic CD146 or targeting of CD146 with an antibody result in much less complex plaques in high-fat diet-fed ApoE-/- mice by causing lipid-loaded macrophages to leave plaques. Collectively, our findings identify CD146 as a novel retention signal that traps macrophages within the artery wall, and a promising therapeutic target in atherosclerosis treatment.
This paper evaluates the recoverable unconventional oil and gas resources around the world, reveals main controlling factors and potential regions for the rich accumulation of unconventional oil and ...gas, and standardizes the classification of seven types of resources (i.e., heavy oil, oil sand, tight oil, oil shale, shale gas, tight gas, and coalbed methane). By virtue of commercial databases for global petroliferous basins, together with single-well data packages in North America and basic data of exploration and development of Chinese companies in unconventional oil and gas resources blocks around the world, contour maps of abundance for global recoverable resources are formed through spatial graphic interpolation of key assessment parameters of seven types of unconventional oil and gas resources on the Geographic Information System (GIS) platform, which systematically evaluate the potential of seven types of unconventional oil and gas resources. The assessment reveals: (1) These seven types of resources around the world are distributed predominantly in 476 formations in 363 petroliferous basins. (2) Total recoverable unconventional oil and gas resources in the world are respectively 442.1 billion tons and 227 trillion cubic meters. (3) Unconventional oil and gas resources can be divided into “source-bound type” and “strata-bound type”. The “source-bound type” resources are mainly controlled by 6 groups of high-quality source rock around the world, among which, the tight oil and gas resources are featured by the “integration of reservoir and source”, presenting the best prospect for the development and application, and the “strata-bound type” oil sand and heavy oil resources, controlled by the transformation of the late structure, are mainly distributed in the slope belt of the Mesozoic-Cenozoic basins, presenting a good prospect for the resource development and application in the shallow layers. (4) Besides hot spots in North America, tight oil in the West Siberia Basin and the Neuquen Basin as well as heavy oil in the Arab Basin will become potential targets for the development of unconventional oil and gas resources in the future.
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