Isolation from small specimens

It is significant that most of the data from which a remarkable uniformity of attack is deduced are derived from small isolated panels. This is the most convenient form of specimen for measurements of corrosion rates by loss of weight but it eliminates the important effect of galvanic currents passing between remote parts of a large structure. It is believed that the experience of civil engineers and other users would not support the conclusion suggested by panel tests that corrosion is no faster in tropical than in temperate waters. 

The small jellyfish Phialidium gregarium (diameter 15-20 mm) used to be abundant at Friday Harbor, Washington, in summer and autumn until about 1990. Levine and Ward (1982) isolated and purified a Ca2+-sensitive photoprotein from this jellyfish and named it phialidin. They extracted the photoprotein from whole specimens with an EDTA-containing buffer. The photoprotein extract was precipitated with ammonium sulfate, and purified by the following methods gel-filtration (BioGel P-150, minus 400 mesh), anion-exchange chromatography (DEAE Bio-Gel A), and gel-filtration (Sephadex G-75, superfine). 

Based on these preliminary investigations, SEM-EDS was used to identify the particles embedded in the sheets. A particle was isolated from the extruded plastic sheeting and analyzed. Figure 40 shows an SEM micrograph at 14,500 x magnification of the particle studied. This specimen is quite small, on the order of 10 pm in diameter. The EDS results are summarized in Table 11 for both this particle and for the polymeric matrix material from which it was harvested. 

Professor von Hevesy and Thai Jantzen separated hafnia from zirconia by repeated recrystallization of the double ammonium or potassium fluorides (20, 26). Metallic hafnium has been isolated and found to have the same crystalline structure as zirconium. A small specimen of the first metallic hafnium ever made is on permanent display at the American Museum of Natural History in New York City. Dr. von Hevesy, who prepared it, presented it to the Museum for the collection of chemical elements (29). A. E. van Arkel and J. H. de Boer prepared hafnium by passing the vapor of the tetraiodide over a heated tungsten filament (26, 30). 

Small specimens of all products, including reaction intermediates isolated from reaction sequences, and particularly samples of fractions isolated as the result of lengthy chromatographic or other purification procedures, should invariably be retained for reference purposes. The commercially available straightsided specimen tubes with polyethylene plug seals, which are available in a range of sizes, are suitable in the case of solid samples. It is usually advantageous to label them with the name and a code reference to enable physical data (elemen-... 

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