The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C−H activation. Herein, we ...reported the synthesis of axially chiral biaryls by Pd‐catalyzed atroposelective C−H olefination. A novel chiral spiro phosphoric acid, STRIP, was identified as a superior ligand for this transformation. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee). Density functional theory was used to gain a theoretical understanding of the enantioselectivities in this reaction.
The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C−H activation. Herein, the synthesis of axially chiral biaryls by Pd‐catalyzed atroposelective C−H olefination is reported. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee).
Sepsis is an intractable disorder, which is associated with high risk of organ dysfunction and even death, while its pathogenesis remains largely unclear. Our study aims to study the research trend ...on sepsis and host immune response, and compare the contribution of publications from different countries, institutions, journals and authors.
We extracted all relevant publications with regard to sepsis and immune response during 1999-2019 from Web of Science. GraphPad Prism 6, and VOSviewer software were used to collect and analyze the publication trend in related field.
We identified a total of 1225 publications with citation frequency of 40511 times up to March 30, 2019. The United States accounted for the largest number of publications (36.3%), 51.9% of total citations as well as the highest H-index (72). The sum of publications from China ranked the second, while the overall citations (1935) and H-index (22) ranked the eighth and the seventh, respectively. Journal of
had published most papers related to the topic on sepsis and immune response. Ayala A SA, has published the most papers in this field (31), while Hotchkiss RS presented with the most citation frequency (3532). The keyword "regulatory T cell" appeared most recently with an average appearing years of 2014.0. The "immunosuppression related research" seemed to be the hotspot in relevant scope.
The United States made the most outstanding contribution within this important field. There is a mismatch between the quantity and quality of publications from China. Latest progress can be tracked in journal of
. Immunosuppression related researches may be hotspots in the near future.
Solid electrolyte interphase (SEI) has been widely employed to describe the new phase formed between anode and electrolyte in working batteries. Significant advances have been achieved on the ...structure and composition of SEI as well as on the possible ion transport mechanism. However, the nucleation and growth mechanism of SEI catches little attention, which requires the establishment of isothermal electrochemical crystallization theory. Herein we explore the virgin territory of electrochemically crystallized SEI. By using potentiostatic method to regulate the decomposition of anions, an anion‐derived SEI forms on graphite surface at atomic scale. After fitting the cur‐rent‐time transients with Laviron theory and Avrami formula, we conclude that the formation of anion‐derived interface is surface reaction controlled and obeys the two‐dimensional (2D) progressive nucleation and growth model. Atomic force microscope (AFM) images emphasize the conclusion, which reveals the mystery of isothermal electrochemical crystallization of SEI.
The nucleation and growth behavior of anion‐derived SEI on graphite electrode is revealed, the number of nucleation sites increases progressively, and each nucleus undergoes 2D growth before overlapping with others. Only when the whole electrode surface is completely covered by reduced products, an ion‐conducting but electron‐insulating polycrystalline film forms, which marks the end of SEI growth.
Herein, we report a “shape fixing via salt recrystallization” method to efficiently synthesize nitrogen-doped carbon material with a large number of active sites exposed to the three-phase zones, for ...use as an ORR catalyst. Self-assembled polyaniline with a 3D network structure was fixed and fully sealed inside NaCl via recrystallization of NaCl solution. During pyrolysis, the NaCl crystal functions as a fully sealed nanoreactor, which facilitates nitrogen incorporation and graphitization. The gasification in such a closed nanoreactor creates a large number of pores in the resultant samples. The 3D network structure, which is conducive to mass transport and high utilization of active sites, was found to have been accurately transferred to the final N-doped carbon materials, after dissolution of the NaCl. Use of the invented cathode catalyst in a proton exchange membrane fuel cell produces a peak power of 600 mW cm–2, making this among the best nonprecious metal catalysts for the ORR reported so far. Furthermore, N-doped carbon materials with a nanotube or nanoshell morphology can be realized by the invented method.
In the paper, the authors establish some generalized fractional integral inequalities of the Hermite–Hadamard type for
(
α
,
m
)
-convex functions, show that one can find some Riemann–Liouville ...fractional integral inequalities and classical integral inequalities of the Hermite–Hadamard type, and generalize and extend some known results.
Abstract
Developing robust nonprecious electrocatalysts towards hydrogen/oxygen evolution reactions is crucial for widespread use of electrochemical water splitting in hydrogen production. Here, we ...report that intermetallic Co
3
Mo spontaneously separated from hierarchical nanoporous copper skeleton shows genuine potential as highly efficient electrocatalysts for alkaline hydrogen/oxygen evolution reactions in virtue of in-situ hydroxylation and electro-oxidation, respectively. The hydroxylated intermetallic Co
3
Mo has an optimal hydrogen-binding energy to facilitate adsorption/desorption of hydrogen intermediates for hydrogen molecules. Associated with high electron/ion transport of bicontinuous nanoporous skeleton, nanoporous copper supported Co
3
Mo electrodes exhibit impressive hydrogen evolution reaction catalysis, with negligible onset overpotential and low Tafel slope (~40 mV dec
−1
) in 1 M KOH, realizing current density of −400 mA cm
−2
at overpotential of as low as 96 mV. When coupled to its electro-oxidized derivative that mediates efficiently oxygen evolution reaction, their alkaline electrolyzer operates with a superior overall water-splitting output, outperforming the one assembled with noble-metal-based catalysts.
NOx− reduction acts a pivotal part in sustaining globally balanced nitrogen cycle and restoring ecological environment, ammonia (NH3) is an excellent energy carrier and the most valuable product ...among all the products of NOx− reduction reaction, the selectivity of which is far from satisfaction due to the intrinsic complexity of multiple‐electron NOx−‐to‐NH3 process. Here, we utilize the Schottky barrier‐induced surface electric field, by the construction of high density of electron‐deficient Ni nanoparticles inside nitrogen‐rich carbons, to facilitate the enrichment and fixation of all NOx− anions on the electrode surface, including NO3− and NO2−, and thus ensure the final selectivity to NH3. Both theoretical and experimental results demonstrate that NOx− anions were continuously captured by the electrode with largely enhanced surface electric field, providing excellent Faradaic efficiency of 99 % from both electrocatalytic NO3− and NO2− reduction. Remarkably, the NH3 yield rate could reach the maximum of 25.1 mg h−1 cm−2 in electrocatalytic NO2− reduction reaction, outperforming the maximum in the literature by a factor of 6.3 in neutral solution. With the universality of our electrocatalyst, all sorts of available electrolytes containing NOx− pollutants, including seawater or wastewater, could be directly used for ammonia production in potential through sustainable electrochemical technology.
The tunable surface electric field induced by Schottky barrier boosts the reduction of NOx− in water for ammonia production. The tunable amounts of Ni nanoparticles inside a nitrogen‐rich carbon support could gradually enhance the surface electric field for enriching and fixation of NOx− anions, achieving a high Faradaic efficiency of 99 % for ammonia production from both electrocatalytic NO3− and NO2− reduction.
Chiral aldehyde catalysis opens new avenues for the activation of simple amines. However, the lack of easy access to structurally diverse chiral aldehyde catalysts has hampered the development of ...this cutting‐edge field. Herein, we report a Pd‐catalyzed atroposelective C−H naphthylation with 7‐oxabenzonorbornadienes for the preparation of axially chiral biaryls with excellent enantioselectivities (up to >99 % ee). This reaction is scalable and robust, which serves as a key step to provide a rapid access to axially chiral aldehyde catalysts through a three‐step C−H functionalization sequence. These chiral aldehydes exhibit better activities and enantioselectivities than the previously reported organocatalysts in the asymmetric activation of glycine derived amides and dipeptides. Moreover, preliminary investigation also discloses that the aldehyde catalyst can effectively override the intrinsic facial selectivity of chiral dipeptide substrates, showcasing the strong chiral induction ability of this type of novel aldehyde catalysts.
A concise synthetic route to chiral aldehyde catalysts with Pd‐catalyzed atroposelective C−H naphthylation as a key reaction is reported. These chiral aldehyde catalysts were successfully employed as ligands in the asymmetric activation of glycine esters enabling a higher level of asymmetric induction and reaction activity. A wide range of enantioenriched biaryls were prepared in synthetically useful yields with excellent enantioselectivities (up to >99 % ee).
Glucocorticoid receptor (GR) modulates extensive biological and pathological processes including tumor progression through diverse mechanisms. The regulatory effects of dexamethasone (DEX), a ...synthetic glucocorticoid, as well as its interaction with GR have been recognized beyond hematologic cancers. In the present study, we investigated the anti-cancer efficacy of DEX and the correlation with GR in pancreatic cancer, a most aggressive malignancy threatening human health. The differential levels of GR expression were examined in two human pancreatic cancer cell lines, PANC-1 and SW1990, as well as in xenografts and patient tumor tissues. DEX significantly inhibited colony formation, migration, and tumor growth of PANC-1 cells expressing abundant GR. The underlying mechanisms involved suppression of nuclear factor κB (NF-κB) phosphorylation and down-regulation of epithelial-to-mesenchymal transition (EMT), interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF). The anti-cancer effects of DEX were partially reversed by GR silencing or combinational administration of GR antagonist, RU486. The dose-dependent efficacy of DEX in tumor growth inhibition was also demonstrated in a GR-positive patient-derived xenograft model along with safety in mice. DEX was less potent, however, in SW1990 cells with poor GR expression. Our findings suggest that DEX effectively inhibits pancreatic tumor growth partially through GR activation. The potential correlation between GR expression and anti-cancer efficacy of DEX may have some clinical implications.
•GR is differentially expressed in pancreatic cancer cell lines and tumors.•DEX inhibits colony formation and cell migration partially through activating GR.•DEX down-regulates EMT and NF-κB phosphorylation.•DEX exhibits GR-dependent anti-cancer efficacy in xenograft models.
The atroposelective synthesis of atropisomers with vicinal diaxes remains rare and challenging, due to the steric influence between the two axes and their unique topology. Herein, we disclose a ...single‐step construction of atropisomers with vicinal C−C and C−N chiral diaxes by cyclopentadiene (Cp)‐free cobalt‐catalyzed intramolecular atroposelective C−H annulation, providing the desired diaxial atropisomers of unique structures with decent stereocontrols of both axes (up to >99 % ee and 70 : 1 dr). The optically pure products bearing fluorophores show circular polarized luminescence (CPL) properties, being candidate materials for potential CPL applications. Atropisomerization experiments and density function theory (DFT) calculations are conducted to study the rotational barriers and rotation pathways of the diaxes.
A single‐step construction of atropisomers with vicinal C−C and C−N chiral diaxes by cyclopentadiene (Cp)‐free cobalt‐catalyzed intramolecular atroposelective C−H annulation with decent stereocontrols (up to >99 % ee and 70/1 dr) was reported. Atropisomerization experiments and DFT calculations are done to study the rotational barriers and pathways of the diaxes.
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