Abstract: A color copier has a control circuit for controlling the exposure of an original to be copied. The control circuit has a processing channel for each of the three primary colors. Each of the channels is associated with photodetectors which is sensitive to the color of the respective channel. The photodetectors sense the intensity of the light in the respective color transmitted through the original and generate signals indicative of the density of the original in that color. The density of the original in each color is compared with the neutral gray density of the original. The difference between the density of each color and the neutral gray density is used to calculate an undercorrection factor for the respective color. The undercorrection factor is used to regulate the exposure time for light of the respective color or the intensity of light of the respective color during exposure.

Abstract: An arrangement for cultivating cells of animal and human tissues in a monocellular layer and the like, has a container bounding an inner chamber for accommodating a nutrient medium, and a plurality of tubular supporting elements for supporting the cells and rotatable about an axis. The tubular rotatable elements extend in an axial direction of the inner chamber of the container. Additional elements are provided for rotating the tubular supporting elements. These additional rotating elements include an axle which defines the axis of rotation, and two end discs each arranged adjacent to and supporting one of the axial ends of the tubular supporting elements. The tubular supporting elements extend in a horizontal direction. However, they can be inclined at an angle relative to the horizontal direction by means of rotation of the end discs in mutually opposite directions.

Abstract: An arrangement for cultivating cells of animal and human tissues in a monocellular layer and the like, has a container bounding an inner chamber for accommodating a nutrient medium, and a plurality of tubular supporting elements for supporting the cells and rotatable about an axis. The tubular rotatable elements extend in an axial direction of the inner chamber of the container. Additional elements are provided for rotating the tubular supporting elements. These additional rotating elements include an axle which defines the axis of rotation, and two end discs each arranged adjacent to and supporting one of the axial ends of the tubular supporting elements. The tubular supporting elements extend in a horizontal direction. However, they can be inclined at an angle relative to the horizontal direction by means of rotation of the end discs in mutually opposite directions.

Abstract: A process for filtering a cellulose acetate solution comprises the steps of providing a solution of cellulose acetate which is dissolved in an organic solvent; adding to the solution a quantity of loose particulate matter and loose fibers so as to form a mixture; and filtering the solution through pores of a filter medium so as to produce a filtrate of the solution, whereby due to addition of the loose particulate matter and the loose fibers clogging of the pores is reduced relative to the amount of filtrate passing through the pores and the effective filtering time of the filtering medium is thereby increased.