Graphitic Armor: A Natural Molecular Sieve for Robust Hydrogen Electroxidation.

Carbon coating layers have been found to improve the catalytic performance of transition metals, which is usually explained as an outcome of electronic synergistic effect. Herein we reveal that the defective graphitic carbon, with a unique interlayer gap of 0.342 nm, can be a highly selective natural molecular sieve. It allows efficient diffusion of hydrogen molecules or radicals both along the in-plane and out-of-plane direction, but sterically hinders the diffusion of molecules with larger kinetic diameter (e.g., CO and O2) along the in-plane direction. As a result, poisonous species lager than 0.342 nm are sieved out, even when their adsorption on the metal is thermodynamically strong; at the same time, the interaction between H2 and the metal is not affected. This natural molecular sieve provides a very chance for constructing robust metal catalysts for hydrogen-relevant processes, which are more tolerant to chemical or electrochemical oxidation or CO-relevant poisoning.

[Cognitive quality of professional divers].

OBJECTIVE: To explore and analyze the cognitive quality of professional divers. METHODS: 165 professional divers were tested with Raven's Standard Progressive Matrices (SPM), 80.8 Neural Type Measuring Form, etc. with 230 common people, 49 sailors and 66 trainee divers as control. RESULTS: There were significant difference among professional divers of different ages in the type of nerve activity, cognitive style, action stability, memory span, time reaction, the perception of space, act of attention and dark adaptation (P < 0.05); Over all, the cognitive quality of professional divers did not differ significantly in education level or working years (P < 0.05); Professional divers were superior to the common people in depth perception, cognitive style, act of attention, action stability, the perception of space and dark adaptation, but inferior to them in intelligence, memory span and time reaction (P < 0.05); There were significant difference in such cognitive indicators as the type of nerve activity, depth perception, kinesthetic memory, cognitive style, the perception of space and dark adaptation (P < 0.05); Compared with the trainee divers, professional divers were significantly better in the type of nerve activity, cognitive style, act of attention, action stability and the perception of space (P < 0.05). CONCLUSION: As a specified profession, diving needs some particular cognitive quality, while the profession itself would affect professional divers' cognitive ability to a certain extent.