Thermochromatism and structural evolution of metastable polydiacetylenic crystals

Article Abstract:

Topochemically polymerized sodium 10, 12-pentacosadiynoate microcrystals show an irreversible red-to-blue chromatic transition accompanied by a distinct structural evolution upon initial thermal treatment, and show a subsequent completely reversible blue-to-red chromatic transition upon further thermal stimuli. Quantum mechanical geometry optimization was employed to explain the lattice dimensional change during the irreversible red-to-blue chromatic transition of the metastable polydiacetylenic crystals.

Acetylene, Chemical properties, Thermochromism

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Two-metal-ion mechanism for hammerhead-ribozyme catalysis

Article Abstract:

A two-metal-ion model for hammerhead-ribozyme catalysis, based on density functional quantum mechanical calculations is described and analyzed. It catalyzes a transesterification reaction that converts a 5',3' diester to a 2',3' cyclic phosphate diester through an S(sub N)2 mechanism.

Catalysis, Catalytic RNA

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How good is Langevin

Article Abstract:

The Langevin equation that is universally applied to describe noise in physical systems of all kinds is discussed. It is found that Langevin cannot describe quantum noise but belongs to the realm of mesoscopic physics.

Noise, Noise (Sound), Mesoscopic systems

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