The author was referring to the steam holiday gems. They are a new feature (released yesterday) in which a steam user can turn their extra junk cards/backgrounds/emotes into gems.. These gems can be used to buy more cards; or, during the upcoming holiday event only, to bid on games.
Acinar cells. 1  Acinar cells are the exocrine (exo=outward) cells of the pancreas that produce and transport enzymes that are passed into the duodenum where they assist in the digestion of food.
Action potential. Several types of cells support an action potential, such as plant cells, muscle cells, and the specialized cells of the heart (in which occurs the cardiac action potential). However, the main excitable cell is the neuron, which also has the simplest mechanism for the action potential.