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Where should the cooling rate be determined in an extended freezing sample?
U Hartmann1, B Nunner, C Körber
1Helmholtz-Institut für Biomedizinische Technik an der RWTH Aachen, Germany.
Cryobiology
|April 1, 1991
Summary
Computer simulations reveal that the center of freezing samples is not representative for cooling rate measurements. An optimal location, approximately two-thirds from the inner surface, is recommended for accurate cryobiological assessments.
Area of Science:
- Cryobiology
- Biophysics
- Computational Modeling
Background:
- Accurate cooling rate determination is crucial for cryobiological experiments.
- Traditional methods often assume uniform cooling within samples.
- Non-planar solidification and external factors complicate cooling dynamics.
Purpose of the Study:
- To simulate transient cooling and solidification in an isotonic solution.
- To evaluate the representativeness of different sample locations for cooling rate measurements.
- To identify an optimal location for accurate cooling rate determination in cryopreservation.
Main Methods:
- One-dimensional computer simulations of cooling and solidification.
- Modeling of external cooling, container, freezing bag, and nonplanar solidification.
- Analysis of cooling rate variations across the sample volume.
Main Results:
- Cooling rate increases from the sample surface towards the center.
- The geometrical center is often the least representative location for cooling rate.
- An optimal measurement location was identified at approximately 2/3 from the inner surface, representing 80% of the sample volume.
Conclusions:
- The geometrical center is unsuitable for determining representative cooling rates in cryopreservation.
- An optimized measurement point ensures more accurate assessment of cooling conditions.
- Cooling rate measurement location significantly impacts cell survival signature interpretation.