ABSTRACT
A protocol for the electrooxidative [3+2] annulation to generate indolo[2,3-b]indoles in an undivided cell is reported. It exhibits good yields with excellent regioselectivities and tolerates various functional groups without external chemical oxidants. Cyclic voltammetry and density functional theory calculations indicate that the [3+2] annulation is initiated by the simultaneous anodic oxidation of indole and aniline derivatives, and the step to determine the rate relies on the combination of radical cations.
ABSTRACT
Highly efficient bifunctional oxygen electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucially important for the rechargeable Zn-air battery, a potential power source for applications in electric vehicles and grid-scale stationary storage systems. Herein, Co3O4@NiCo2O4 double-shelled nanocages (Co3O4@NiCo2O4 DSNCs) with hierarchical hollow structure and oxygen vacancies were designed and synthesized via annealing metal-organic frameworks. Co3O4@NiCo2O4 DSNCs with large specific surface area and three-dimensional interconnected mesopores and cavity not only provide more reaction sites, but also offer an efficient transport environment for reactants. Moreover, oxygen vacancies on the surfaces improve the capture of oxygen species to enhance the reactivity of the catalyst. Consequently, Co3O4@NiCo2O4 DSNCs displayed excellent bifunctional electrocatalytic performance, with a positive half-wave potential of 0.81 V (vs. reversible hydrogen electrode, RHE) for ORR (approaching the potential of commercial Pt/C catalyst) and a low potential of 1.65 V at 10 mA cm-2 for OER (exceeding Pt/C). In a practical demonstration, the Zn-air battery using Co3O4@NiCo2O4 DSNCs as the cathode delivered a satisfactory power density of 102.1 mW cm-2, comparable to the Zn-air battery with a Pt/C cathode, and exhibited much longer cycling stability.
ABSTRACT
OBJECTIVE: To demonstrate the spatial organization of neurons, astrocytes and vessels in rat brain. METHODS: Cerebral vascular was shown by vivi-perfusion with ink. Glial fibrillary acidic protein (GFAP) immunohistochemistry and nissl's staining were performed on the serial sections of frozen brain tissues. RESULTS: Astracytes distributed along the branches of blood vessels, and neurons in the region of the relatively rich blood vessels. Neurons and astrocytes presented regional distribution. CONCLUSION: This method can well indicate the spatial organization of neurovascular unit, the regional differences in the distribution may be related to physical activities and the corresponding adjustment function.