A container for a sealed secondary cell containing an electrode plate group is provided comprising a wall forming a base in electrically conducting material, the base comprising a peripheral portion, a closure member portion and a weakened portion joining the peripheral portion to the closure member portion and designed to rupture in the presence of an excess pressure inside the container. The supplemental feeding bottle device has a first piece with a top outside thread, a bottom outside thread, a rotatable o-ring, a flat round surface at the bottom and a gap for baby food to be held and dispersed into the feeding bottle. The sub-trees can have leaf nodes at varying depths based on ranks of the leaf nodes, and the master tree can similarly provide inputs from the sub-trees at varying depths based on simulation depths for the sub-trees. The device comprises a pair of electrodes of which at least one is a transparent electrode, and a liquid crystal layer between the pair of electrodes comprising a liquid crystal composition comprising at least one dual-frequency switchable smectic liquid crystal, and at least one dichroic dye. For example, the frequency adjuster might include a plurality of capacitors that are selectable using a digital control signal, and selection logic may adjust the digital control signal based on a received indication associated with the oscillator’s frequency. A disclosed polishing head includes at least one rotating head to apply a downward force; and a plurality of vacuum cells to hold the wafer via a vacuum force and to convey a least some of the downward force from the at least one rotating head to the wafer.