A flow control valve controls a flow of water through a passage to a brine tank of a water treatment apparatus. The inlet end can be connected to an influent channel positioned at a level above the head cell apparatus. , of formula, wherein R1, R2, R3 and R4 are as defined, are found to be useful as pharmaceuticals, e. There are also described methods for determination and isolation of organic molecules using the artificial antibodies as well as therapeutic and diagnostic methods using these antibodies.