A phenomenon was observed in our laboratory as we studied the effect of chain length of fatty amine capped on the nanogold upon their 2D arrangement. The nanogolds modified with C12NH2, C16NH2, C18NH2 have been used in this investigation and were arranged by the method of LB technique. Electronmicrograms showed that the length of aggregates is proportional to the chain length of the capped amine CnNH2. The longer the chain length is, the straighter the aggregates will be and the more compact 2D arrangement could be formed. Linear aggregates has been found in the 2D pattern formation of nanoparticles without template, and these kinds of aggregates might be of great importance in the formation of 2D arrangement of nanoparticles.
The combination of the genetic engineering and chemical additive has been used in an attempt to obtain much longer M-state lifetime of bacteriorhodopsin-PVA film. Different compositions of D96N-mutant bacteriorhodopsin-PVA film with the diaza-15-crown-5 (1,4,10-trioxa-7,13- diazacyclopentadecane) additive were prepared and their spectral and kinetic transformation were investigated by absorbance spectroscopy. As the molecular ratio of BRD96N/diaza-15-crown-5 ranging from 1:50 - 1:150, the decay of the M-state was slowed down gradually. The fitting of the M-state decay kinetics curves needs a three-exponential- function to get sufficiently small residuals. At the highest additive concentration, the photochromism time of BRD96N film could last as long as one and a half hours. This provides a benefit to the BRD96N as a candidate material for optical applications under ambient conditions.
The photochromic retinal protein bacteriorhodopsin (BR) is found in the cell membrane of Halobacterium salinarium. It is the key protein for photosynthetic growth of H.salinarium. BR shows an exceptional stability towards chemical, thermal, and photochemical degradation. In this paper, we propose a system of optical information storage in a BR polymer film. A three- wavelength EDRAW (Erase Direct Read After Write) experiment was performed. The photoexcited P(490) state shows a permanent storage property confirmed by our contrast ratio experiments. We have performed the reversible operations of 'write' and 'erase' with the BR polymer film over hundreds of cycles in our experiments. The readout contrast ratio is very sensitive to the intensity and wavelength of probe beam and the recorded data can be readout from 530 to approximately 630 nm with different contrast ratio. Within the range of 570 to approximately 600 nmm, the better contrast ratio can be obtained. Considering the erasing effect for the reason of absorption of P state, both higher contrast ratio and nondestructive reading can be realized by using 594 nm as the readout wavelength. The experimental result such BR material is very suitable for long-term photochromic information storage.
The lifetime of M-state in the bacteriorhodopsin photocycle was remarkably prolonged in bR-gelatin film by using 1,4,7,10-tetraoxa-13- azacyclopentadecane (aza-15-crown-5) as chemical additive. Spectral and kinetic measurements were carried out at room temperature. It is observed that the M-state in the film has a long lifetime ((tau) 1/e) of 360s with bR/aza-15-crown-5 weight ratio of 1:3 under room conditions. To investigate the mechanism of aza-15-crown-5 on the photocycle of bR 15-crown-5 was used as chemical additive too. It was suggested that the strong complexing property towards H+ of aza-15- crown-5 played an important role in the prologation. The fitting of the M-state decay kinetics curves corresponded to a sum of three and two exponential components for bR-films using aza-15-crown-5 and 15-crown-5 as chemical additive respectively.
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