Porosity loss, change

The consequences of shape change are densification and loss of electrode porosity, increased current density caused by loss of zinc surface area, and finally earlier passivation. Two different forms of pasi-vation can stop the discharge of a zinc electrode before the active material is exhausted. "Spontaneous" passivation occurs... 

Electrolyte Structure Ohmic losses contribute about 65 mV loss at the beginning of life and may increase to as much as 145 mV by 40,000 hours (15). The majority of the voltage loss is in the electrolyte and the cathode components. The electrolyte offers the highest potential for reduction because 70% of the total cell ohmic loss occurs there. FCE investigated increasing the porosity of the electrolyte 5% to reduce the matrix resistance by 15%, and change the melt to Li/Na from Li/K to reduce the matrix resistivity by 40%. Work is continuing on the interaction of the electrolyte with the cathode components. At the present time, an electrolyte loss of 25% of the initial inventory can be projected with a low surface area cathode current collector and with the proper selection of material. 

Cells of E. coli can adapt to at least 100-fold changes in osmolarity. Because of the porosity of the bacterial outer membrane the osmolarity of the periplasmic space is normally the same as that of the external medium. However, the inner membrane is freely permeable only to water and a few solutes such as glycerol.b The bacterial cells avoid loss of water when the external osmolarity is high by accumulating K+ together with anions such as... 

As we have seen, the formation of a-Al203 is normally associated with a considerable loss of surface area. It must not be assumed, however, that this is accompanied by the removal of all porosity. The pore structure is always changed by high-temperature treatment, but a distinction must be made between open and closed pores, and it is only the former that can be characterized by physisorption measurements. 

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