极光这一现象是由“太阳风”所造成的。“太阳风”是太阳发射的带电原子内粒子流，它和大气层中的分子相互发生作用就引起了极光。

The phenomena are caused by the "Solar Wind" - streams of electrically charged sub-atomic particles emitted by the Sun - interacting with molecules in the atmosphere.

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以前大部分研究集中于宏观工程参数控制和活性污泥特性对系统运行的作用过程，针对系统内活性污泥的分子生态学研究尚少。

Now the study of MBR focuses on macro parameter control and system running effected by sludge characteristics, and there are little studies on molecule ecology of active sludge.

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根据超声作用机理，超声技术可以克服聚合物表面和吸附质间的亲和力，加快聚合物内的扩散以及表面的分子传递。

Ultrasound can overcome the affinity of the adsorbates with the adsorbent surface and accelerate the molecular transport towards and from the adsorbent surface.

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In general, inside of a cell molecules move by a process called diffusion.

总的来说,细胞内的分子通过扩散作用来移动

耶鲁公开课 - 生物医学工程探索课程节选