Two or three channels imprinted onto the plastic square contain either a normal cell growth medium or a chemical under study, such as growth factor.

印在塑料方块上的两、三条通道通常包含一个正常的细胞生长介质或者研究中的化学物质如生长因子。

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The Replicator ships with a small plastic square its makers use to test the printer in order to make sure that everything is running well.

ENGADGET: MakerBot Replicator impressions: the dawning of 3D printers in every home?

Data was stored on rewritable magneto-optical disks 2.5in (64mm) in diameter housed for protection in a square plastic shell.

BBC: Sony to make last MiniDisc stereo system in March

And could it be trout farming below the dam at Dolores square plastic-lined pools in which writhing motion could be detected, as if someone were boiling a great stew of fish rather than breeding them?

NEWYORKER: Or Else