The toner bottle exchangeably used in an image forming apparatus. When the textile layer is attached to the sole, at least a portion of the textile layer is disposed between the open shoe and the skin of the foot. Total area and current may be reduced by the present invention because the number of inverters comprising each stage is equal. A relational knowledge database can be used for storing copies of and information regarding unsolicited e-mails such that the information can be queried, manipulated, or analyzed. This method allows purification of stem cells from adult heterogeneous cell populations on a large scale basis without requirement of expensive equipment, and without requiring the presence of cell surface markers. A magnetic unit is formed at a front end of the head so as to attract objects in operation.