Remarkable proteolytic activity of imidazoles attached to cross-linked polystyrene

The insoluble resins synthesized by attaching imidazoles to poly(chloromethylstyrene-co-divinylbenzene) effectively hydrolyzed albumin with half-life as short as 20 min at pH 7 and 25 degrees C. Thus, peptide hydrolysis was accomplished with imidazole in an artificial system for the first time. The imidazole-based artificial proteinases manifested optimum activity at pH 7-8. The proteolytic activity of the imidazole-based artificial proteinases exceeded that of previously reported organic artificial proteinases including catalytic antibodies. High proteolytic activity was observed when imidazole was attached to the resin through the C-2 atom instead of the N atom. The catalytic activity was greatly reduced when the content of imidazole was lowered. This indicates catalytic cooperation of at least two proximal imidazole moieties attached to the resin. Possible mechanisms for the effective protein hydrolysis by the proximal imidazoles are presented.     

Molecular dynamics simulation study on graphene-nanoribbon-resonators tuned by adjusting axial strain

A tunable graphene-nanoribbon (GNR)-resonator was investigated via classical molecular dynamics simulations. Resonance frequencies increased with increasing externally applied gate-force and axial-strain, and could be tuned above several hundred GHz. Tunable resonance frequencies achieved from the gate force were higher than those achieved from the axial-strain. The operating frequencies of GNR-resonators without axial-strain or with small axial-strains were most widely tuned by the gate, and almost linearly increased with increasing mean deflection. As the axial strain increased, the tunable ranges of the GNR-resonators were exponentially decreased, although the operating frequencies increased. GNR-resonators without axial-strain could be applied to wide-range-tuners, whereas GNR-resonators with high axial-strain could be applied to high-frequency-fine-tuners.