基于Boltzmann方程对C_(3)F_(8)/CF_(3)I/CO_(2)三元环保型混合气体的绝缘性能研究

为研究一种新型SF_(6)替代环保绝缘气体介质,采用密度泛函理论(DFT)从微观结构层面上深入地分析C_(3)F_(8)作为一种SF_(6)替代环保绝缘气体的可行性,利用两项近似的Boltzmann方程对300 K下C_(3)F_(8)/CF_(3)I/CO_(2)三元环保混合绝缘气体介质的绝缘特性进行了分析,计算三元环保混合气体的电子能量分布函数、电子群参数和协同效应系数等多种微观参数,分析了这些参数随C_(3)F_(8)混合气体比例的变化情况,并与同比例下的c-C_(4)F_(8)/CF_(3)I/CO_(2)三元混合气体的微观参数进行了对比和分析。在约化电场强度E/N低于418 Td时,从扩散系数、电子漂移速度的角度上来看,C_(3)F_(8)三元混合气体的性能优于c-C_(4)F_(8)三元混合气体,在C_(3)F_(8)比例低于7%时,C_(3)F_(8)三元混合气体的绝缘强度高于30%SF_(6)/70%CO_(2)的混合气体,此时的三元混合气体在中低压设备中具有一定的应用潜力。此外,当C_(3)F_(8)气体体积分数为10%时,三元混合气体协同性最好。文中的研究从理论上验证了C_(3)F_(8)/CF_(3)I/CO_(2)替代SF_(6)的可能性。

Numerical Study on Comparison of Negative and Positive Surface Discharge in c-C_(4)F_(8)/CF_(3)I/CO_(2) Gas Mixture

The dynamics of negative surface discharges in c-C_(4)F_(8)/CF_(3)I/CO_(2) gas mixture is investigated here with a 2D fuid model.The distributions of ion concentration,electric field strength and photon flux during the propagation of the streamer are obtained by solving the drift-diffusion equations of particles and Poisson's equation,and the photon flux variation function during the propagation is also fitted.It is found that the streamer branches occur when the streamer transitions from the upper surface of the insulator to the side surface,and then when the streamer approaches the plane electrode,the photon flux will increase significantly.On this basis,the positive and negative surface discharge models are compared in terms of streamer characteristics,particle characteristics and streamer branches.It is found that the streamer has a higher electron concentration and electric field in the positive model.The streamer develops“floating”in the positive surface discharge,while it is close to the surface of the insulator in the negative model.In addition,the negative streamer branch has a wider width and develops further.

寡霉素在叶绿体中的作用部位

寡霉索可抑制光下DTT激活的Mg^(2+)-ATP酶活力并促进质子流出,这两种效应对温度的反应相似,并受膜能化状态的影响。 寡霉素对在光下以胰蛋白酶激活的叶绿体膜上Mg^(2+)-ATPase和脱离了膜的Ca^(2+)-ATPase都有抑制作用,但对经NEM修饰的叶绿体膜上Mg^(2+)-ATPase活力没有影响,且其促进质子流出的效应也消失,在暗中经胰蛋白酶活化的Ca^(2+)-ATPase对寡霉素不敏感。由此推断寡霉素抑制光激活的ATPase和促进质子流出的效应是光引起膜能化导致CF_1变构,γ亚基暴露,而使寡霉素能与之结合的结果,因此寡霉素在叶绿体上的作用部位是在CF_1中,而与线粒体在F_0上有所不同。