Rapid freezing procedure

Table 3 Summary of Procedures for Rapid Freezing of Tissues...

Bray who has pioneered the rapid freeze method for studying fast kinetics, has recently used this method in conjunction with XAS The procedure involves quenching reacting solutions by squirting them into a cold imiscible solvent and allows the preparation of a series of samples, each frozen at a particular reaction time (from about 3 ms upwards). Bray and co-workers used this method to Study the structural... 

The unique g = 16 EPR signal of diferrous MMOH allowed its reaction with O2 to be followed using rapid freeze-quench procedures in conjunction with EPR... 

Freeze-thaw tests in the concrete series were conducted according to ASTM C 666 (Procedure B rapid freeze-thaw under air conditions). It was applied on standard prismatic specimens at the dimensions of 80x80x360 mm. The experiment was conducted after the specimens had been cured for 28 days. Heat transfer calculations were made in order to determine how long the heat in the specimens would take to reach the optimal heat required for the experiment so that the freeze-thaw test could be made in the deep frost according to ASTM C 666. Therefore, the central heat of the specimens (20 °C) was lowered to -20 °C. The central heat of the specimens left in the water was increased to 5.4 °C. 30 cycles were made altogether, with the central heat adjusted in such a way that it would vary between -20 °C (2 hours and 40 minutes) and 5.4 °C (36 minutes). 

In an examination of the literature dealing with the study of non-aqueous solutions, it is striking that there is virtually no experimental procedure for the investigation of matter that has not been employed to study solvation or other processes involving solvent effects. Scarcely does a new method appear in the arsenal of the analyst than it is applied to this field of solution chemistry. This tendency is well shown by the example of typical methods, developed for the investigation of solid substances, such as Mossbauer spectroscopy and ESCA. The application of these to the study of solvation processes was made possible by the elaboration of the technique of quenching solutions by rapid freezing. 

The most reliable method of determining the polymer content of a bacterial cell culture or partially purified digest is to freeze-dry the sample and extract gravimetrically the PHB into chloroform solution. Indeed this is the technique used to calibrate all other methods but it is rather time-consuming and several more rapid analytical procedures have been developed. 

Cultured human skin fibroblasts, harvested by brief trypsinization, were suspended to various cell concenent-ration inlO mM Tris HCl buffer pH 7.4 and extracted by thrice rapid freezing and thawing in dry ice and aceton or by sonication. The protecting effect of PRPP and other compounds was studied by their addition to the cell suspension prior to the extraction procedures. HGPRT and... 

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