A lower region having a composition of Alx1Gax2Inx3N is formed through epitaxial growth by a CVD method, and subsequently, an upper region having a composition of Aly1Gay2Iny3N is formed through epitaxial growth by a CVD method. In other words, the present invention relates to the \u201ccleaning up\u201d of or purification of a lipophilic fluid such that it can be re-used in a lipophilic fluid system. The current image data includes both a dark noise signal and an image signal. Magnetic attraction force between the magnetic element of the container assembly and the magnetic element of the plate assembly is exerted when the container assembly is placed in proximity to the plate assembly.