Nonequilibrium freezing

With most single cells so far examined, the survivals obtained with nonequilibrium freezing procedures and vitrification are no better than those obtainable with equilibrium freezing procedures. But vitrification procedures may be necessary for the successful preservation of tissues and organs, which appear not to be able to tolerate the formation of ice in capillaries and other spaces between the cells. 

Mazur, P. (1990). Equilibrium quasi-equilibrium, and nonequilibrium freezing of mammalian embryos. Cell Biophy. 17, 53-92. 

At F4, solidification is completed. It is thus seen that nonequilibrium freezing is characterised by... 

Table 1 Shifts in pH During Nonequilibrium Freezing with Phosphate Buffer Sy.stems...

Table 3 Impact of Formulation on Crystallization The Effect of Sucrose on the pH Shift in Sodium Phosphate Buffer Systems During Nonequilibrium Freezing...

One can see such frozen structures that were formed due to an auto-catalytic reaction in tektites.12 There are several other geological processes that show such freezing of nonequilibrium structures.13... 

Nonequilibrium reactions can be detected by determining metabolite concentrations in the tissue of interest. Conventionally, a tissue sample is rapidly frozen by compression between metal plates that have been cooled to 77 K by immersion in liquid nitrogen (freeze-clamping). This procedure rapidly halts any enzymatic processes that might alter the metabolite concentrations the concentrations can then be determined by enzymatic or chemical assays. Recently, 31P-NMR spectroscopy has shown considerable value in measuring the concentrations of such metabolites as ATP, ADP, AMP, phosphate, and phosphocreatine in living cells or tissues. 

The glass transition as a reference state can be used to explain all transformation in time, temperature, and structure composition effects between different relaxation states for technologically practical food systems in their nonequilibrium nature. Among others, specific examples include reduced activity and shelf stability of freeze-dried... 

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