分子马达的三态周期跳跃模型

研究了在一维三态周期跳跃模型下分子马达的定向运动 .对于给定的任意初始分布 ,得出了与时间有关的几率分布的解析表达式 ,包括到达稳态之前的所有的瞬态过程 ,由此可获得马达在各个时刻的漂移速度v、扩散系数D以及描述马达随机性质的随机参数r(randomnessparameter ) .同时还计算了马达到达稳态所需要的特征时间 .并把计算结果同实验进行了比较 .     

Synergistic effect of total ionizing dose on single event effect induced by pulsed laser microbeam on SiGe heterojunction bipolar transistor

The synergistic effect of total ionizing dose(TID) on single event effect(SEE) in SiGe heterojunction bipolar transistor(HBT) is investigated in a series of experiments. The SiGe HBTs after being exposed to 60 Co g irradiation are struck by pulsed laser to simulate SEE. The SEE transient currents and collected charges of the un-irradiated device are compared with those of the devices which are irradiated at high and low dose rate with various biases. The results show that the SEE damage to un-irradiated device is more serious than that to irradiated SiGe HBT at a low applied voltage of laser test. In addition, the g irradiations at forward and all-grounded bias have an obvious influence on SEE in the SiGe HBT, but the synergistic effect after cutting off the g irradiation is not significant. The influence of positive oxide-trap charges induced by TID on the distortion of electric field in SEE is the major factor of the synergistic effect. Moreover, the recombination of interface traps also plays a role in charge collection.     

Cys对近红外荧光蛋白PAiRFP1光谱学行为的影响研究

PAiRFP1是一种以细菌光敏色素为模板,改造得到的光激活荧光蛋白。与其他光激活荧光蛋白相比,它最大的优势是激发、发射都在近红外区域。本论文围绕该蛋白中含有的8个半胱氨酸残基,开展了定点突变、光谱学检测等工作,发现(1)在8个单突变体中,仅有Cys-29突变改善了光激活蛋白的分子亮度,其它突变都削弱了近红外荧光;(2)伴随着环境氧化、还原条件的改变,C29S突变近红外荧光显著降低,这说明该位点的半胱氨酸残基对于维持该近红外荧光蛋白在氧化还原环境中的稳定性具有重要作用,相关机理尚待深入研究。