Deganello S
Scan Electron Microsc. 1986(Pt 4):1721-8.
The phase changes calcium oxalate trihydrate-weddellite, weddellite-calcium oxalate monohydrate and calcium oxalate trihydrate-whewellite are individually examined at the atomic level from a theoretical point of view; concomitantly the topological requirements necessary for phase stability are clarified for each structure type. In solution a sequential series of phase transitions according to the steps calcium oxalate trihydrate-weddellite-whewellite is not likely to be energetically favoured; direct conversion of calcium oxalate trihydrate to whewellite should be, instead, ordinarily expected. It is formally demonstrated that along two axial directions a set of atoms is in essentially identical positions in both weddellite and whewellite. This notwithstanding, it is concluded that epitactic catalysis cannot and should not be considered a common mechanism for the formation of whewellite from weddellite (and vice versa) or of kidney stones in general.
从理论角度在原子水平上分别研究了三水合草酸钙-水草酸钙、水草酸钙-一水合草酸钙以及三水合草酸钙-二水草酸钙的相变；同时阐明了每种结构类型的相稳定性所需的拓扑要求。在溶液中，按照三水合草酸钙-水草酸钙-二水草酸钙的步骤进行的一系列连续相变在能量上不太可能是有利的；相反，通常预期三水合草酸钙会直接转化为二水草酸钙。正式证明，在两个轴向方向上，一组原子在水草酸钙和二水草酸钙中的位置基本相同。尽管如此，得出的结论是，外延催化不能也不应被视为从水草酸钙形成二水草酸钙（反之亦然）或一般肾结石形成的常见机制。
