Abstract: A tube-shaped film, made of fluorine resin, has a fold-free, smooth, and uniform inner peripheral surface formed thereon by a surface treatment. An apparatus for treating the inner peripheral surface of the tube-shaped film includes a holding device for holding the tube-shaped film on the inner peripheral surface of a cylindrical body with a cylindrical configuration of the tube-shaped film maintained. A treatment device is inserted into the cylindrical body to treat the inner peripheral surface of the tube-shaped film held on the inner peripheral surface of the cylindrical body. The holding device and the treatment device make a uniform linear motion relative to each other and a uniform rotary motion relative to each other.

Abstract: A method for surface modification of a fluorine resin by irradiating the surface of the fluorine resin containing a heat-resistant light-absorbing polymeric material and/or a light-absorbing material is with laser light. Surface properties of the fluorine resin molded articles, particularly adhesion and wetting properties, can be greatly improved by a simple operation with high efficiency.

Abstract: The disclosure relates to a filter in use for centrifugal separator including a filter film between a sample chamber and a filtrate chamber. The filter film is inclined or parallel to an axis of the filter. Accordingly, when the filter is utilized for either the angle rotor type and swing rotor type of centrifugal separators, the filter is positioned, during operation, so as to be inclined or parallel to the direction of the centrifugal force so that the residue contained in the liquid sample in the sample chamber moves radially outwardly with respect to the axis of the rotors so as to slide on the filter film or so as to leave from the filter film. Thus, the filter film will not easily result in clogging with the residue so that the high filtration speed can be maintained for a long period of time.