Thermal Degradation Kinetics of Deoxybenzoin Polymer

The thermal degradation behavior of 4, 4-bishydroxydeoxybenzoin-polyphosphonate( BHDB-PPN) was investigated by gas chromatograph-mass spectrometer( GC-MS)and thermogravimetric analysis( TGA). It was found that BHDBPPN exhibited a different char formation way from the previous proposed mechanism based on the residue analysis by Fourier transform infrared spectra( FTIR) and the gas phase analysis by GC-MS. The thermal degradation kinetics was studied through TGA at various heating rates to identify the activation energy of BHDBPPN at two decomposition stages which were mainly attributed to the evolved phenol and benzene respectively. It was demonstrated that the activation energy at the second stage was much higher than that at the first stage,indicating that more energy was required to break the P—C bond to form benzene in comparison to the formation of phenol.     

色噪声下双头分子马达停留时间

分子马达是一类能将化学能直接转变为机械能的蛋白质大分子，它们沿相应微管作定向运动，其定向运动机制对生物高分子合成有重要的指导意义．引入分子马达双头之间的耦合作用势函数，建立分子马达在色噪声作用下的双头耦合模型．采用二阶龙格一库塔算法求解Langevin方程，结合Monte Carlo模拟方法，计算得到马达的停留时间和跃迁时间．进一步讨论了耦合系数、噪声强度、外部作用力对停留时间及跃迁时间的影响，并作了相应的分析．