Harder than diamond?

Article Abstract:

The search for a superhard carbon nitride continues. Experiments on making the proposed superhard phase were sparked by a trio of papers by Cohen and Liu, where they made calculations from first principles to predict a very high elastic modulus and correspondingly high hardness for a postulated compound, C3N4 with a structure equivalent to Si3N4. Teter and Hemley also studied carbon nitride models in silicon-nitride-like configurations, a graphitic version and a cubic version. American chemist Charles Lieber and his group have also been persistent in forming carbon nitrides using reactive sputtering and laser-ablation of carbon from a graphite surface.

Nitrides

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Illusion and view stability

Article Abstract:

There is one example of an illusory surface which contradicts Carman and Welch's concept of view stability. The latter proposes that the shape of illusory contours and surfaces remain the same despite changes in the observer's position, as observed using solid luminance edges. The opposite was observed when the illusory contours were produced by the ends of fine lines. These observations indicate that different neurophysiological processes might be involved in the perception of these two illusory surfaces.

Observations, Form perception, Optical illusions, Form perception (Psychology)

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On the threshold of stability

Article Abstract:

Research on carbenes is examined in detail. These compounds are short-lived, and are not easy to research due to the presence of a carbon atom which is extremely reactive.

Analysis, Chemical research

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