牺
=
牛
+
西
:
Marie Curie (xi) is selling an ox (牛) for cheap in front of the space station (Ø1) as a loss leader (牺). To pepper the ox a little up she puts a cowboy hat (西) on his head.
牲
=
牛
+
生
:
The bull (牛) got a child and is watching over it in its cradle (生) in front of the engine ((e)ng1). He has to be very attentive because Sherlock Holmes (sh) wants to use the newborn as a sacrificial animal (牲).