Mercury zinc, primary applications

Besides the family of manganese dioxide cells with zinc as negative electrode during the last decades manifold other battery systems have been developed and produced for the market. More capacity and higher load ability were the motivation for research. Here can be named the mercury zinc cell, produced in millions of button cells each year for hearing aids, calculators, watches, cameras, etc. Never was it possible to create one universal cell doing the job for all kinds of applications. Always it has to be noticed that primary cells are specialists, exactly designed for a special application. So in 1980 the smallest button cell of the world was made by Varta with a diameter of 6.8 mm and a thickness of 0.7 mm for wristwatches. 

Other primary cells are also used as batteries for certain applications. In some instances, the battery must be quite small. For a medical device, such as a heart pacemaker, a battery should not only be small, but long lasting. Mercury batteries have come to fill this role. In the mercury battery, shown in Figure 13.14, zinc is the anode as in the alkaline dry cell ... 

This battery type has been phased out in most applications because of the problems of disposal. The product of the reaction is liquid mercury which has a tendency to pool and can create a toxic hazard in landfills. Most countries have banned the use of mercury batteries in consumer applications for this reason. Other battery systems such as lithium primary batteries, zinc air, and alkaline batteries have to a large extent replaced mercury batteries. 

The intracellular localization of stress proteins is problematic for the evaluation of the response in humans. Because the cells for the assay of stress proteins are not readily available through noninvasive procedures, the application of this response to human monitoring is limited. Recently, however, enhanced synthesis of stress proteins was demonstrated in primary cultures of human lymphocytes exposed to several metals (Yamada and Koizumi 1993). The specificity of the response was dependent on the metal to which the cultures were exposed. For example, cadmium and zinc induced both hsp70 and MT, while cobalt and triphenyltin induced only hsp70. Conversely, copper, mercury, nickel, and silver all induced synthesis of MT, but not of hsp70. Enhanced synthesis of stress proteins has also been demonstrated in vivo in lymphocytes and spleen cells excised from mice exposed to hyperthermia (Rodenhiser et al. 1985). 

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