Abstract: To provide a photoelectric conversion element capable of further improving performance in a photoelectric conversion element using an organic semiconductor material. The photoelectric conversion element includes a first electrode and a second electrode arranged to face each other, and a photoelectric conversion layer 17 provided between the first electrode and the second electrode, in which the photoelectric conversion layer 17 includes a first organic semiconductor material and a second organic semiconductor material, and at least one of the first organic semiconductor material or the second organic semiconductor material is an organic molecule having a HOMO volume fraction of 0.15 or less or a LUMO volume fraction of 0.15 or less.

Abstract: In a fixed-bed ion exchange process for treating a fluid, wherein adsorption and regeneration are performed in countercurrent flow, the whole ion exchange resins are removed from the ion exchange column portionwise, either intermittently or continuously, subjected to backwash and then returned to the ion exchange column. The whole bed of the resins is replaced by one round in this process, and therefore the distribution of the ions in the resin bed after backwash treatment is substantially the same as before, whereby a very efficient ion exchange is possible without increase in amount of the regenerant.

Abstract: In a fixed-bed solid-fluid contacting process, wherein adsorption and regeneration are performed in countercurrent flow, a portion of contaminated solid particles in the bed is extracted from the bed for washing, simultaneously when a fluid is treated by passing through the bed. The solid particles extracted are washed and recycled to the bed at the time of other operations, for example, regeneration step. The process is improved in the time cycle of treatment which is shortened and the pressure loss which is decreased. The process is also free from disturbance of bed and excellent in treatment efficiency. A simple and compact apparatus is available for the process. Typical example of application is ion exchange reaction.