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Polarographic measurements showed that Catechol complexes of vanadium(V) adsorb onto the hanging mercury drop electrode. This property forms the basis of a sensitive eiectrochemical technique by which dissolved vanadium in seawater can be determined directly. The reduction current of adsorbed complex ions of vanadium is measured by differential pulse cathodic stripping voltammetry, preceded by a period of collection of a few minutes. The peak potential Is at --0.7 V. Optimal experimental parameters were found to be a catechol concentration of 2 X IO-* M, a collection potential of -0.1 V, and a soiutlon pH of 6.9. The limit of detection is 0.3 nM vanadium after a 2-min collection with a stirred soiutlon, which is decreased further to 0.1 nM after a 15-min collection.

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Active matrices often related with high grade display devices, due to application of the storage elements, typically thin film transistor (TFT). Because of the complex procedures in the manufacturing TFT, investment of the high value manufacturing equipments and clarification plants is necessary, hence increasing the manufacturing cost of the flat panel, and more importantly, causing the pollution of water and air. As the contribution of TFT array merely exists in supplying storage function for the pixels of the display panel, large efforts have been made to find suitable cells that have bistable effect, so as to substitute the effect of TFT. As the bistable cell is just the storage pixel, one could construct a bistable cell to skip the needs of TFT active matrices. The paper is to introduce currently available bistable display devices in the following field: liquid crystal bistable displays with cholesteric liquid crystals, which is an example to introduce the bistable technology; iMod display devices based on mechanic induced bistable and light interference, which shows the possibility to construct bistable display; and the display based on solid powder movement in air or in vacuum, so called liquid powder displays, which shows how to improve the existed display.