Morganthaler J J, Price C A
Biochem J. 1976 Feb 1;153(2):487-90. doi: 10.1042/bj1530487.
When polystyrene "latex" beads are centrifuged to equilibrium in gradients of Nalcoag 1030, Nalcoag 1034A and Ludox 130M, which are commercial formulations of colloidal silica, the beads at densities that may be markedly lower or higher than the bulk density. Addition to the gradient of small amounts of certain polymers restores the banding densities towards the expected value. These findings closely mimic previously observed "density shifts" of biological particles. A possible model for this anomalous behavior is discussed.
当聚苯乙烯“乳胶”珠在Nalcoag 1030、Nalcoag 1034A和Ludox 130M（胶体二氧化硅的商业配方）的梯度中离心至平衡时，珠子的密度可能明显低于或高于堆积密度。向梯度中添加少量特定聚合物可使条带密度恢复到预期值。这些发现与先前观察到的生物颗粒的“密度转移”非常相似。讨论了这种异常行为的一种可能模型。
