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A W Robards

Publications and source records attributed to A W Robards.

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A device for the rapid freezing of biological specimens under precisely controlled and reproducible conditions.

The construction and preliminary testing of a device is described which can be used to freeze biological specimens in any cryogenic liquid at temperatures down to the nitrogen freezing point (63 K) and which can operate in the pressure range 1.3 kNm-2 to 1 MNm-2. Ultra-rapid freezing can be carried out in a subcooled cryogenic liquid either hyperbarically or at atmospheric pressure. Slow freezing rates can be achieved by cooling the specimens in a controlled manner in the vapour phase above the liquid bath.

Atmospheric Pressure

Ultrastructural study of poly- -hydroxybutyrate granules from Bacillus cereus.

The freeze-etching technique was used to examine the effects of fracturing and etching on the appearance of poly-beta-hydroxybutyrate granules from Bacillus cereus. These granules were examined in extracts isolated by hypochlorite or by sonic treatment, and also in fixed and unfixed intact cells; in the latter case they were compared with granules in thin sections of intact cells. After freeze-fracturing, the diameter of the granules in intact cells was between 240 and 720 nm. The granules consisted of a central core, of diameter between 140 and 370 nm, which occupied less than 50% of the volume of the granule and which was either stretched or removed on fracturing; the core was surrounded by an outer coat which may be bounded by a membrane.

Bacillus cereus

Freeze-etching.

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Freeze Etching