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Sample size: an important parameter in flash‐cooling macromolecular crystallization solutions
Author(s) -
Chinte U.,
Shah B.,
DeWitt K.,
Kirschbaum K.,
Pinkerton A. A.,
Schall C.
Publication year - 2005
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889805005029
Subject(s) - vitrification , flash (photography) , glycerol , crystallization , liquid nitrogen , materials science , glass transition , sample (material) , analytical chemistry (journal) , thermodynamics , chemistry , nuclear engineering , chromatography , optics , polymer , composite material , physics , organic chemistry , nuclear physics , engineering
The effect of sample size on flash‐cooling was assessed using an assortment of Hampton Screen I solutions (Hampton Research). These were cryogenically cooled to ascertain the minimum glycerol concentration needed for vitrification of solutions. Solutions were `flash‐cooled' in 1.0, 0.5 and 0.1 mm commercial cryoloops, using a 100 K nitrogen stream generated by an Oxford 600 Cryostream. The loops were visually examined and then X‐ray diffraction data were collected and evaluated for ice formation. The glycerol concentration needed for vitrification was found to decrease significantly as sample size decreased; detailed key data are presented in tabular form. Glass transition temperatures, T g , were measured for solutions leading to successful vitrification in the 1 mm cryoloop. The trends in the required concentration of glycerol and resultant T g can be understood through a simplified heat‐transfer analysis. This analysis points to a critical cooling time period for successful vitrification.