A Proposal of Standardized Nomenclature in the Study of Crystallization in Biological Systems, e.g. Urolithiasis
Scientific reports on chemical equilibria and dynamics of crystallization related to urolithiasis vary greatly in the terminology that they apply to similar processes. As an example, one may see reports of crystal growth rate or crystallization rate in which both rates are derived similarly from the disappearance of some critical ion (e.g. oxalate) from solution over a given period of time. Do these rates refer to the change in dimensions of a single crystal, to the change in mass of the single crystal, or to the total mass transfer rate (from solute to solids) onto crystals in the mother liquor? In many instances the latter is meant and is reported as “crystal growth” or “crystal growth rate”. Is there a definition of this concept already in existence? Yes, and it exists in conjunction wich chemical and chemical engineering disciplines. It is the separation intensity factor R, or more widely in industrial parlance, the rate of make, expressed as mM ⋅ min-1 2. The rate of make is in no way a fundamental crystallization parameter but in fact varies with nucleation rate, growth rate, total available super- saturation, crystal size, and the total crystal surface area available for growth. For non-flow batch systems, R is equal to the rate of change of solids concentration, dMT/dt, and is the variable measured when solids rather than liquor concentrations are observed. Do other fairly standard terms exist that can be applied to studies of crystallization in urine? Yes. Table 1 lists these and we would propose their adoption by other workers in the realm of urolithiasis or any other study of crystallization in biological systems3.
KeywordsNucleation Rate Crystal Growth Rate Calcium Hydroxy Apatite Standardize Nomenclature Supersaturation Ratio
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