Freezing methods chamber used

After quick freezing in liquid nitrogen and fracture, another etching method was used at — 90 °C for less than 1 min in a 1.33 x 10-4 Pa chamber. The etched sample was cooled to — 130°C and coated with platinum and carbon in the same vacuum chamber and transferred to the scanning electron microscope at — 130 °C. The observed structure was closer to reality than that obtained by the method previously described. This is called the cryo-SEM technique [32]. CryoSEM images are shown in Fig. 4 which presents the structural change by stretching [16]. 

Freeze-drying is another method sometimes used to preserve whole animals, particularly small ones that are too delicate for traditional skinning. Methods have been developed for the impregnation of soft tissues with resin. This is done in a vacuum chamber, and is usually done to preserve specimens of internal organs for teaching purposes. 

An osmometer is an instrument which measures the osmolality of a solution, usually by determining the freezing point depression of the solution in relation to pure water, a technique known as cryoscopic osmometry. A small amount of sample is cooled rapidly and then brought to the freezing point (Fig. 6.1), which is measured by a temperature-sensitive thermistor probe calibrated in mosmol kg . An alternative method is used in vapour pressure osmometry, which measures the relative decrease in the vapour pressure produced in the gas phase when a small sample of the solution is equilibrated within a chamber. 

Method of use, (1) For interior of freeze-drier - the chamber temperature is raised to 40 °C using hot air or steam and beta-propiolactone admitted to give a final concentration of 2-4 mg per litre. The biocide is left for a contact time of 1-2 hours (longer for spores), prior to removal by outgassing for 2 hours. 

Method of use. The chamber is evacuated and then warmed to 40 °C with hot air or steam to give an RH of 25-50%. Ethylene oxide is then injected into the chamber to a concentration of 400-1000 mg per litre and sterilising conditions maintained for 4—8 hours. The freeze-drier is then returned to atmospheric pressure and the ethylene oxide vented from the drier. An explosion-proof mixture of 60% ethylene oxide and 40% methyl bromide has been used for decontamination. Ethylene oxide has been more widely used in the USA than in the UK for sterilising freeze-driers. 

Method of use. Freeze-driers may be contaminated by (i) In closed freeze-drier procedure is to evacuate the chamber and admit formaldehyde vapour at an RH of at least 70%. The vapour is left in contact for a minimum of 4 hours prior to venting the chamber for 2-4 hours. 

The merit of Malinin s work is the comparative study of water content of bones by reproducible methods. The measurement of water vapor pressure during the drying cannot be used dirctly to determine the RM, as Malinin correctly states. Measurement of the description rates (DR) provide a means to follow quantitatively the course of desorption drying. The method is described in Section 1.2.2, but cannot be applied in an installation used by Malinin because the condenser cannot be separated from the chamber by a valve. By using the data given in the paper of Malinin it is possible to estimate the freeze drying process of bone transplants as follows ... 

Old polyurethane on rims may be removed either on a lathe, by solvent attack, or by freezing in liquid nitrogen. For more complex shapes, the reinforcing may be recovered by the above methods as well as by pyrolysis in a specially designed chamber, where the material is heated in the absence of air to above the decomposition temperature of the polyurethane. The fumes are then burned using special after-burners. 

Residual moisture is the low level of water, usually in the range of less than 1-3% (wt/wt), remaining in a freeze-dried product after the freeze-drying (vacuum sublimation) process [1-5] is complete. Nail [6] has described in-process methods to monitor the endpoint of freeze-drying using residual gas analysis, pressure rise, comparative pressure measurement, and product temperature measurement. Roy and Pikal [7] used an electronic moisture sensor inside the lyophilization chamber. Residual moisture [8] content is important in the final freeze-dried product because it affects the potency of the product, its long-term stability, and the official shelf life of the product. 

Dual-chamber syringe. For delivery of two established vaccines (e.g., polyribosyl ribitol phosphate conjugated to tetanus toxoid and diphtheria-tetanus-whole cell pertussis and inactivated poliovirus vaccine) at the same time, a dual-chamber syringe delivery system can be used. The proximal chamber may contain a vaccine in the freeze-dried solid state, and the distal chamber contains a vaccine in the liquid formulation that allows reconstitution of the vaccine in the proximal chamber. The immune response by the dualchamber delivery of vaccination was equivalent to that by the separate-injection method of vaccination. The dual-chamber syringe can be used for safe and effective delivery of two different vaccines that are not yet available as a single formulation for pediatric applications. ... 

This method uses a turret with multiple ports (a manifold) to which flasks and vials are fitted via suitable valves (see Fig. 2.3). The product is either frozen in a freezer (by direct submersion in a low-temperature bath) or shelf-frozen, depending on the nature of the initial and end product, and also on the volume to be freeze-dried. The pre-frozen product must be immediately attached to the drying chamber or manifold to prevent... 

Shortly after we had run this comparison study, our own aged freeze-drier collapsed into obsolescence. In order to make this method work, the freeze-drier must be specially constructed, without resin in the vacuum chamber and with traps placed in the vacuum line to prevent the back-diffusion of oil vapors from the pump to the vacuum chamber. While we have been awaiting the rejuvenation of our own instrument, rebuilt to these specifications, Michael McKinnon, of our laboratory, has developed a variation of the Russian evaporation method. In this method, as in the freeze-drying method, the great problem is avoiding contamination. Fortimately, when contamination does occur, it seems to affect an entire batch of samples. It is therefore possible to detect the contamination by the judicious use of standards. This method gives values for DOG of the same order as the lowest freeze-drying values or the Sharp (27) direct injection values. 

The freeze-drying method uses sublimation (solid to vapor transformation) to dry specimens. This method requires freezing a specimen rapidly to below —80°C in a chamber. At that temperature, the chamber is degassed under a low pressure of below 0.1 Pa. The specimen can be dried in such a condition after several hours to several days. 

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