Shock freezing

T. J. Kemp, University of Warwick Noting the very low quantum yield for intramolecular electron transfer in low temperatures displayed by your porphyrin-quinone model compound, would it not be possible to shock-freeze a solution undergoing irradiation at a higher temperature (and giving a workable concentration of paramagnetic species) in order to determine a low-temperature spectrum with the particular aim of observing a possible Am = 2 transition ... 

Fig. 2.2. Automatic filling of a product to be freeze dried in vials, which are cooled by LN2. In the installation the following steps are carried out with a speed of up to 9000 vials per hour Precooling of the vials down to -180 °C, filling of the vials, shock freezing of the product, placing the stoppers on the vials (photograph Groninger Co. GmbH, D-7180 Crailsheim).

Stroage at 4°C should be as short as possible. Longer storage after shock freezing at — 80°C... 

Shock-freeze the solution by carefirlly dipping the vial into an ethanol/dry ice-bath, and store in a -80°C freezer until the freeze drying process is to commence. 

Fig. 8 SEM images of the aggregates formed by a PS258-fc-PZLLys57 and b PS258-h-PZLLysiog in dilute CCI4 solution specimens were prepared by shock-freezing a 0.2 wt% polymer solution with liquid nitrogen and subsequent freeze-drying [43]...

If permeability of the cell is a problem, raw extracts or purified enzymes should be used. The membrane can be modified or broken by grinding with glass beads, drying the cells with air or acetone, lyophilization, autolysis, osmotic shock, freezing and thawing, ultrasonification or treatment with lysozyme or detergents 327. 

Add sucrose to a final concentration of 30% and shock-freeze the protein solution in 50 pL aliquots using thin-walled 200-pL reaction tubes in liquid nitrogen. Store at -80°C. 

Resin fines] thermal or physical shock/freeze/thaw. 

Figure 10 Cryo-TEM image of SPEB. The particles consist of a core onto which a dense layer of PAA chains has been grafted. The micrograph results from shock-freezing an aqueous dilute salt-free solution. Reprinted with permission from Wittemann, A. Drechsler, M. Talmon, Y. ...

Split the liquid formulation into aliquots and shock-freeze them by dropping into liquid nitrogen. The frozen samples can be stored at -25°C for an (almost) unlimited period of time. 

Traditional electron microscopy is conducted in high vacuum, which imposes specific efforts to sample preparation. Particles from colloidal suspensions have to be deposited onto an appropriate substrate (e.g. on carbon or silica films) and dried. Alternatively, the suspensions can be shock-freezed and particles are subsequently excavated from the continuous phase by special cryo-preparation techniques (Schmidt et al. 1994, pp. 694—705). The sample preparation can be considerably reduced with environmental scanning electron microscopes (ESEM), which are operated up to 1000 Pa and, thus, even facilitate the analysis of wet surfaces. However, the ease in operation is at the expense of resolution (Danilatos 1993). 

Shock-freeze the aliquots in liquid nitrogen and store at -80°C. Aliquots are stable at -80°C for at least 1 year but should not be re-frozen. 

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