Influence of polarization orientation of violet light on the diffraction efficiency of bacteriorhodopsin

When a grating is recorded in a bacteriorhodopsin film by two linear parallel polarized beams together with anauxiliary violet light, the diffraction efficiency has a dependence on the polarization orientation of the violet light as well as its intensity. A method for calculating the diffraction efficiency of gratings in bacteriorhodopsin is proposed based on the two-state photochromic model, considering the saturation effect and the polarization status of all the involved lights. It is found that the polarization orientation of the violet light produces an approximate-cosine and an approximate-sine modulation on the steady-state diffraction efficiency separately at low and high intensities, respectively. The parallel polarized violet light can improve the steady-state diffraction efficiency to a larger degree than the perpendicularly polarized violet light when both are at their optimal intensities. The optimal intensity for the parallel polarized violet light is lower than that of the perpendicular polarized one. Thus, the improvement of the steady-state diffraction efficiency is less sensitive to the intensity of perpendicular polarized violet light than to that of parallel polarized violet light. (C) 2008 Optical Society of America.

Simulation of a Monolithic Integrated CMOS Preamplifier for Neural Recordings

A monolithic integrated CMOS preamplifier is presented for neural recording applications. Two AC-coupied capacitors are used to eliminate the large and random DC offsets existing in the electrode-electrolyte interface. Diode-connected nMOS transistors with a negative voltage between the gate and source are candidates for the large resistors necessary for the preamplifier. A novel analysis is given to determine the noise power spectral density. Simulation results show that the two-stage CMOS preamplifier in a closed-loop capacitive feedback configuration provides an AC in-band gain of 38.8dB,a DC gain of 0,and an input-referred noise of 277nVmax, integrated from 0. 1Hz to 1kHz. The preamplifier can eliminate the DC offset voltage and has low input-referred noise by novel circuit configuration and theoretical analysis.

Vc“二步发酵法”最佳组合生产菌系的选育及其“工程菌”的构建

对24株不同组合的Vc“二步发酵法”生产菌系中筛选出了最佳组合生产菌系H_(19)S_(19)。对该菌系的形态学及生理生化特性的研究表明，H_(19)为地衣芽孢杆菌，S_(19)的分类地位目前还难以确定，但与尹光琳等报道的氧化葡萄糖酸杆菌相比，具有许多新的不同特点。用单亲本灭活的原生质体融合技术进行了H_(19)和S_(19)以及132及S_(19)的原生质体融合，共获得400株重组子，其中有2株产生2--酮基--L--古龙酸产量高且稳定性好的重组子。其中一株是由H_(19)和S_(19)原生质体以H_(19)为背景融合产生的，另一侏是132和S_(19)原生质体以S_(19)为背景产生的。