An easily dispersible cake of precipitated silica, wherein the precipitated silica has a BET specific surface area of at least 220 m2g. The metal oxide film stacks contain a metal oxide coupling layer disposed on a metal oxide host layer, each layer having different grain structuressizes. Reducing such toxins generates damaging reactive oxygen species, so it is important to find a defense for these bacteria against the associated oxidative stress. The n-side electrode is formed of an ohmic contact electrode and a bonding electrode. When the mobile receptacle is taken out from or inserted into the opening part, at least one of the catch parts in the locating device selectively catches the engaging part so that the mobile receptacle may reach out from or enter the receptacle assembly.