Fetal bovine serum specific cell type. When changing from batch to batch it is usual to adapt the cells to the new batch of material, for example, by mixing 50% of the old serum with 50% of the new serum and allowing the cells to acclimatise to the new material. Serum is stored frozen to preserve the stability of components such as growth factors. When serum is thawed, some precipitation may be seen. This is a normal phenomenon and it does not compromise the quality of serum in any way. The precipitate may be removed by transferring the serum to sterile tubes and
Blood, toil, tears, and sweat are "It [poetry] is forged slowly and painfully, link by link, with blood and sweat and tears" (Lord Alfred Douglas, 1919), "Blood, sweat, and tear-wrung millions" (Lord Byron, 1823), and "...mollifie/ It with thy teares, or sweat, or blood" (John Donne, 1611). In Latin, Cicero and Livy had used the phrase "sweat and blood". "We are in the preliminary stage of one of the greatest battles in history... That we are in action at many points—in Norway and in Holland—, that we have to be prepared in the Mediterranean. That the air battle is continuous, and that many preparations have