High-pressure freezing, technique

Because of the too slow cooling rate of the High Pressure Freezing technique (10,000 K/s), water pools mean sizes were overestimated by TEM. Indeed, HPF essentially guarantees to produce a snapshot of the reverse microemulsion phase though this... 

Riehie U and Hdchii M 1973 The theory and technique of high pressure freezing Freeze-Etching Technique and Appiications ed E L Benedetti and P Favard (Paris Societe Frangaise de Microscopie Eiectronique) pp 31-61... 

Standard chemical fixation fails to preserve extracellular materials. In contrast, Os04-microwave heating or the high-pressure freezing-freeze-substitution technique is able to preserve such materials (Eggli and Graber, 1994). The former technique is simpler... 

Another technique—pres sure-shift freezing—also shows promise. In this technique the material is subjected to high pressure (200 MPa) and cooled to -15 C. Under these conditions the water does not freeze. However, when the pressure is released suddenly, many small ice crystals form. This has two results the small ice crystals do not rupture any structures present, but by dehydrating the unfrozen material the remaining stmcture is aggregated and stiffened by the introduction of secondary cross-links. At low concentration of solids there are too few interconnecting chains for there to be a load-bearing continuum, and the material tends to flocculate and settle out. 

Ion-molecule reactions have also been investigated at high pressures in the Cl source of a tandem-sector mass spectrometer [43,44]. In this technique it is feasible to freeze out the ion-molecule adduct by collisional stabilization with a neutral bath gas and to study the adduct by the usual CID approach. 

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