Covalent organic frameworks (COFs) as an emerging class of crystalline porous materials have received much attention due to their tunable porosity, modifiable skeletons, and atomically precise ...structures. Besides, COFs can provide multiple high-rate charge carrier transport (electron, hole, and ion) pathways, including conjugated skeletons, overlapped π electron clouds among the stacked layers, and open channels with a variable chemical environment. Therefore, they have shown great potential in electrochemical energy storage (EES) and conversion (EEC). However, in bulk COFs, the defects always impede charge carrier conduction, and the difficulties in reaching deep-buried active sites by either electrons or ions lead to limited performance. To overcome these obstacles, numerous research studies have been carried out to obtain COF nanosheets (NSs). This review first describes the preparation strategies of COF NSs
via
bottom-up and top-down approaches. Then, the applications of bulk COFs and COF NSs in EES and EEC are summarized, such as in batteries, supercapacitors, and fuel cells. Finally, key challenges and future directions in these areas are discussed.
The current advances, structure-property relationship and future perspectives in covalent organic frameworks (COFs) and their nanosheets for electrochemical energy storage (EES) and conversion (EEC) are summarized.
A copper‐catalyzed carbonylative borylation of unactivated alkyl halides has been developed, enabling efficient synthesis of aliphatic potassium acyltrifluoroborates (KATs) in high yields by treating ...the in situ formed tetracoordinated acylboron intermediates with aqueous KHF2. A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary, and tertiary alkyl halides are all applicable. In addition, this method also provides facile access to N‐methyliminodiacetyl (MIDA) acylboronates as well as α‐methylated potassium acyltrifluoroborates in a one‐pot manner. Mechanistic studies indicate a radical atom transfer carbonylation (ATC) mechanism to form acyl halide intermediates that are subsequently borylated by (NHC)CuBpin.
A copper‐catalyzed carbonylative borylation of unactivated alkyl halides enables one‐step synthesis of acylborons which can be further transformed into potassium acyltrifluoroborates (KATs) as well as N‐methyliminodiacetyl (MIDA) acylboronate in a one‐pot manner.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We present a scheme to entangle two magnon modes in a cavity magnomechanical system. The two magnon modes are embodied by collective motions of a large number of spins in two macroscopic ...ferrimagnets, and couple to a single microwave cavity mode via magnetic dipole interaction. We show that by activating the nonlinear magnetostrictive interaction in one ferrimagnet, realized by driving the magnon mode with a strong red-detuned microwave field, the two magnon modes can be prepared in an entangled state. The entanglement is achieved by exploiting the nonlinear magnon-phonon coupling and the linear magnon-cavity coupling, and is in the steady state and robust against temperature. The entangled magnon modes in two massive ferrimagnets represent genuinely macroscopic quantum states, and may find applications in the study of macroscopic quantum mechanics and quantum information processing based on magnonics.
Since their development in the 1970s, cross-coupling reactions catalyzed by transition metals have become one of the most important tools for constructing both carbon−carbon and carbon−heteroatom ...bonds. Traditionally, organohalides were widely studied and broadly used as the electrophile, both in the laboratory and in industry. Unfortunately, the high cost, environmental toxicity, and sluggish preparation often associated with aryl halides can make them undesirable for the large-scale syntheses of industrial applications. However, with the further development of catalytic systems, and particularly of the ligands contained therein, a variety of electrophiles have now been successfully applied to cross-coupling reactions. Oxygen-based electrophiles have attracted much attention due to their ready availability from phenol and carbonyl compounds. Initially, aryl and alkenyl triflates were used in cross-coupling reactions due to their high reactivity; however, low moisture stability and high cost hampered their application. Later, with the development of highly efficient catalytic systems, the less reactive sulfonates and phosphates were successfully employed in cross-coupling reactions. Although they have higher stability and can be easily prepared, low atom economy remains an obstacle to their broader utility. Our group has worked to directly apply the abundant and readily available oxygen-containing compounds, such as phenols, alcohols, ethers, and carbonyl compounds, to cross-coupling reactions. In this Account, we describe our recent efforts in transition-metal-catalyzed cross-coupling reactions of new O-based electrophiles via C−O bond activation. We began by developing the methylation of aryl methyl ethers and benzyl methyl ethers via Ni-catalyzed selective C−O bond cleavage. With the refined Ni-based catalytic system, we further applied aryl/alkenyl carboxylates and carbamates to Suzuki−Miyaura, Negishi, and Kumada−Tamao−Corriu reactions to construct various biaryl scaffolds and highly substituted alkenes. To further improve the carbon atom economy, we developed the diaryl sulfates as one-by-one electrophiles (that is, both aryl groups are used in the reaction). Most recently, we have achieved the first successful cross-coupling reaction of magnesium naphtholates with aryl Grignard reagents. These results extend aryl and benzyl ethers, aryl and alkenyl carboxylates/carbamates, and magnesium naphtholates as novel electrophiles in cross-coupling reactions. More importantly, these studies contribute to our better understanding the intrinsic nature of C−O bonds, which were traditionally considered “inert” but clearly show enormous synthetic potential with the proper catalysts.
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IJS, KILJ, NUK, PNG, UL, UM
Innate immunity is an indispensable arm of tumor immune surveillance, and the liver is an organ with a predominance of innate immunity, where mucosal-associated invariant T (MAIT) cells are enriched. ...However, little is known about the phenotype, functions, and immunomodulatory role of MAIT cells in hepatocellular carcinoma (HCC).
The distribution, phenotype, and function of MAIT cells in patients with HCC were evaluated by both flow cytometry (FCM) and
bioassays. Transcriptomic analysis of MAIT cells was also performed. Prognostic significance of tumor-infiltrating MAIT cells was validated in four independent cohorts of patients with HCC.
Despite their fewer densities in HCC tumor than normal liver, MAIT cells were significantly enriched in the HCC microenvironment compared with other mucosa-associated organs. Tumor-derived MAIT cells displayed a typical CCR7
CD45RA
CD45RO
CD95
effector memory phenotype with lower costimulatory and effector capabilities. Tumor-educated MAIT cells significantly upregulated inhibitory molecules like PD-1, CTLA-4, TIM-3, secreted significantly less IFNγ and IL17, and produced minimal granzyme B and perforin while shifting to produce tumor-promoting cytokines like IL8. Transcriptome sequencing confirmed that tumor-derived MAIT cells were reprogrammed toward a tumor-promoting direction by downregulating genes enriched in pathways of cytokine secretion and cytolysis effector function like
and
and by upregulating genes like
, and
(
). High infiltration of MAIT cells in HCC significantly correlated with an unfavorable clinical outcome, revealed by FCM, qRT-PCR, and multiplex IHC analyses, respectively.
HCC-infiltrating MAIT cells were functionally impaired and even reprogrammed to shift away from antitumor immunity and toward a tumor-promoting direction.
.
Proper design and simple preparation of nonnoble bifunctional electrocatalysts with high cost performance and strong durability for the oxygen reduction reaction (ORR) and the oxygen evolution ...reaction (OER) is highly demanded but still full of enormous challenges. In this work, a spontaneous gas‐foaming strategy is presented to synthesize cobalt nanoparticles confined in 3D nitrogen‐doped porous carbon foams (CoNCF) by simply carbonizing the mixture of citric acid, NH4Cl, and Co(NO3)2·6H2O. Thanks to its particular 3D porous foam architecture, ultrahigh specific surface area (1641 m2 g−1), and homogeneous distribution of active sites (C–N, Co–Nx, and Co–O moieties), the optimized CoNCF‐1000‐80 (carbonized at 1000 °C, containing 80 mg Co(NO3)2·6H2O in precursors) catalyst exhibits a remarkable bifunctional activity and long‐term durability toward both ORR and OER. Its bifunctional activity parameter (ΔE) is as low as 0.84 V, which is much smaller than that of noble metal catalyst and comparable to state‐of‐the‐art bifunctional catalysts. When worked as an air electrode catalyst in rechargeable Zn–air batteries, a high energy density (797 Wh kg−1), a low charge/discharge voltage gap (0.75 V), and a long‐term cycle stability (over 166 h) are achieved at 10 mA cm−2.
Co nanoparticles confined in 3D N‐doped porous carbon foams are fabricated by a spontaneous gas‐foaming strategy. Owing to the synergistic effect of the particular 3D porous foam architecture, ultrahigh specific surface area, and homogeneous distribution of active sites, the optimized CoNCF delivers a remarkable bifunctional activity and long‐term charge/discharge cycling stability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Traditional Chinese medicine treatment of diseases has been recognized, but the material basis and mechanisms are not clear. In this study, target prediction of the antigastric cancer (GC) effect of ...Guiqi Baizhu (GQBZP) and the analysis of potential key compounds, key targets, and key pathways for the therapeutic effects against GC were carried out based on the method of network analysis and Kyoto Encyclopedia of Genes and Genomes enrichment. There were 33 proteins shared between GQBZP and GC, and 131 compounds of GQBZP had a high correlation with these proteins, indicating that the PI3K‐AKT signaling pathway might play a key role in GC. From these studies, we selected human epidermal growth factor receptor 2 (HER2) and programmed cell death 1‐ligand 1 (PD‐L1) for docking; the results showed that 385 and 189 compounds had high docking scores with HER2 and PD‐L1, respectively. Six compounds were selected for microscale thermophoresis (MST). Daidzein/quercetin and isorhamnetin/formononetin had the highest binding affinity for HER2 and PD‐L1, with Kd values of 3.7 μmol/L and 490, 667, and 355 nmol/L, respectively. Molecular dynamics simulation studies based on the docking complex structures as the initial conformation yielded the binding free energy between daidzein/quercetin with HER2 and isorhamnetin/formononetin with PD‐L1, calculated by molecular mechanics Poisson‐Boltzmann surface area, of −26.55, −14.18, −19.41, and −11.86 kcal/mol, respectively, and were consistent with the MST results. In vitro experiments showed that quercetin, daidzein, and isorhamnetin had potential antiproliferative effects in MKN‐45 cells. Enzyme activity assays showed that quercetin could inhibit the activity of HER2 with an IC50 of 570.07 nmol/L. Our study provides a systematic investigation to explain the material basis and molecular mechanism of traditional Chinese medicine in treating diseases.
We are committed to establishing a systematic research method based on network pharmacology, multitarget molecular docking, molecular dynamics simulation, and protein and experimental verification in vitro and in vivo, to establish a systematic analysis method for traditional Chinese medicine (TCM) treatment of diseases. We aim to provide a possible theoretical and experimental basis for the standardization and internationalization of TCM.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The direct functionalization of C-H bonds has drawn the attention of chemists for almost a century. C-H activation has mainly been achieved through four metal-mediated pathways: oxidative addition, ...electrophilic substitution, σ-bond metathesis and metal-associated carbene/nitrene/oxo insertion. However, the identification of methods that do not require transition-metal catalysts is important because methods involving such catalysts are often expensive. Another advantage would be that the requirement to remove metallic impurities from products could be avoided, an important issue in the synthesis of pharmaceutical compounds. Here, we describe the identification of a cross-coupling between aryl iodides/bromides and the C-H bonds of arenes that is mediated solely by the presence of 1,10-phenanthroline as catalyst in the presence of KOt-Bu as a base. This apparently transition-metal-free process provides a new strategy with which to achieve direct C-H functionalization.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The coronavirus disease 2019 (COVID-19) pandemic continues to create tremendous uncertainty in workplaces. Building on a social identity perspective, this study develops and tests a model of how and ...why COVID-19-associated uncertainty affects employee work outcomes. The model differentiates uncertainty as either internal (job insecurity) or external (perceived environmental uncertainty) to the organization and reveals their different effects on employee organizational identification, which positively affects employee work outcomes (work effort, organizational citizenship behavior, and performance). With a latent change score to model intraindividual changes, we found that increases (or decreases) in job insecurity before versus during the pandemic related to subsequent decreases (or increases) in organizational identification, whereas increases (or decreases) in perceived environmental uncertainty before versus during the pandemic related to subsequent increases (or decreases) in organizational identification; increases (or decreases) in organizational identification then related to increases (or decreases) in positive work outcomes. These findings complement existing theoretical views that uncertainty typically leads to poor performance by inducing anxiety, and that organizational identification suffers during a crisis such as COVID-19. In turn, this research offers practical implications to help organizations avoid discouraging and even encourage greater organizational identification and performance during crises.
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CEKLJ, FFLJ, NUK, ODKLJ, PEFLJ, UPUK
Proximity-driven metalation has been extensively exploited to achieve reactivity and selectivity in carbon–hydrogen (C–H) bond activation. Despite the substantial improvement in developing more ...efficient and practical directing groups, their stoichiometric installation and removal limit efficiency and, often, applicability as well. Here we report the development of an amino acid reagent that reversibly reacts with aldehydes and ketones in situ via imine formation to serve as a transient directing group for activation of inert C–H bonds. Arylation of a wide range of aldehydes and ketones at the β or γ positions proceeds in the presence of a palladium catalyst and a catalytic amount of amino acid. The feasibility of achieving enantioselective C–H activation reactions using a chiral amino acid as the transient directing group is also demonstrated.
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BFBNIB, NMLJ, NUK, ODKLJ, PNG, SAZU, UL, UM, UPUK
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