Electron microscopic observation

Most tests of the validity of the BET area have been carried out with finely divided solids, where independent evaluation of the surface area can be made from optical microscopic or, more often, electron microscopic observations of particle size, provided the size distribution is fairly narrow. As already explained (Section 1.10) the specific surface obtained in this way is related to the mean projected diameter through the equation... 

The polyethylene crystals shown in Fig. 4.11 exist as hollow pyramids made up of planar sections. Since the solvent must be evaporated away prior to electron microscopic observation, the pyramids become buckled, torn, and/ or pleated during the course of sample preparation. While the pyramidal morphology is clearly evident in Fig. 4.1 la, there is also evidence of collapse and pleating. Likewise, the ridges on the apparently planar crystals in Fig. 4.1 lb are pleats of excess material that bunches up when the pyramids collapse. 

Champion and Rohde [42] investigate the effects of shock-wave amplitude and duration on the Rockwell C hardness [41] and microstructure of Hadfield steel over the pressure range of 0.4-48 GPa (pulse duration of 0.065 s, 0.230 ls, and 2.2 ps). The results are shown in Fig. 7.8. In addition to the very pronounced effeet of pulse duration on hardness shown in Fig. 7.8, postshoek electron microscope observations indicate that it is the final dislocation density and not the specific microstructure that is important in determining the hardness. 

Massive barite crystals (type C) are also composed of very fine grain-sized (several xm) microcrystals and have rough surfaces. Very fine barite particles are found on outer rims of the Hanaoka Kuroko chimney, while polyhedral well-formed barite is in the inner side of the chimney (type D). Type D barite is rarely observed in black ore. These scanning electron microscopic observations suggest that barite precipitation was controlled by a surface reaction mechanism (probably surface nucleation, but not spiral growth mechanism) rather than by a bulk diffusion mechanism. 

Very fine-grained sulfides (n x 10 xm), which are common in Kuroko ores (Shikazono, unpublished), have not been reported from midoceanic ridge chimneys. However, SEM (scanning electron microscope) observations of Kuroko and Mariana chimneys indicate that the minerals are aggregates of very fine-grained crystals. Therefore, SEM observation is necessary to measure grain size of individual mineral crystals. However, data from SEM observations of midoceanic ridge chimneys are scarce. 

Wang R.T. and Halpem M. (1980a). Light and electron microscopic observations on normal structure of vomeronasal of Garter snakes. Morphol Jb 164, 47-68. 

The steady-state potential (or current density) is related to a steady growth of the porous oxide into the solution, maintaining a constant number of pores and a constant pore radius. This scheme is supported by electron microscopic observations reported by Xu et a/.102... 

Determann, A., Mehlhom, H. and Ghaffar, F.A. (1997) Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda Filarioidea). Parasitology Research 83, 591—603. 

Baker, J.T.P. 1969. Histological and electron microscopical observations on copper poisoning in the winter flounder (Pseudopleuronectes americanus). Jour. Fish. Res. Bd. Can. 26 2785-2793. 

Benedetti E, Emmelot P. Electron microscopic observations on negatively- stained plasma membranes isolated from rat liver. J Cell Biol 1965 26 299-304. 

Huxley HE, Zubay G. Electron microscope observations on the structure of microsomal particles from Escherichia coli. JMol Biol 1960 2 10-18. 

Maruyama K, Kume N, Okuda M. A scanning electron microscopic observation of chromosomes in freeze-fractured cells of Vicia faba. J Electron Microsc 1985 34 162-168. 

Strauss, E. W., Padykula, H. A., Ladman, A. J, and Gardner, F. H., Histo-chemical, histologic and electron microscopic observations on jejunal epithelium in non-tropical sprue. Am.. Pathol. 35, 716 (1959). 

Cohen, A. S., and Calkins, E. (1959). Electron microscopic observations on a fibrous component in amyloid of diverse origins. Nature 183, 1202-1203. 

Gaffet, E., Tachikart, M., El Kedim, O., and Rahouadj, R., Nanostructural materials formation by mechanical alloying-morphologic analysis bases on transmission and scanning electron microscopic observations, Mater. Charact. 36, 185, 1996. 

Hirano A, Levine S, Zimmerman HM. 1967. Experimental cyanide encephalopathy Electron microscopic observations of early lesions in white matter. J Neuropathol Exp Neurol 26 200-213. 

Kendall MW. 1979. Light and electron microscopic observations of the acute sublethal hepatotoxic effects of mirex in the rat. Arch Environ Contam Toxicol 8 25-41. 

As an extension of their previous work, the Tachibana group (82, 83) studied the collapse fragments that occur when monolayers of 12-hydroxystearic acid are compressed slowly (18 A /molecule hr) at surface areas of less than 21 A /molecule, the normal cross-sectional area of a hydrocarbon chain. The collapsed monolayers were transferred from the subphase to hydrophilic supports by a horizontal lifting method for electron microscopic observation, which revealed (Fig. 30) flat platelets when the sample was racemic and twisted... 

The diameters of the pores of the surface layer of Loeb-Sourlrajan-type cellulose acetate membranes have been reported by several authors (1-6). The reported values of the diameters cover the range between 10 A and 60 A. For electron microscopic observations, the replication method must be used. In order to obtain the excellently contrasted Images the surface of the sample Is shadowed with heavy metals In vacuum. In many cases the Pt-Pd alloy has been used as a pre-shadowlng metal. But the resolution of the Pt-Pd replica Is at the level of about 50 A, since the size of the evaporated particles Is between 20 X and AO X (7, 8, 9). If the pore sizes are In the range of the above-mentioned level, we cannot observe them. 

By means of the more advanced replication technique using tungsten as a pre-shadowing metal, the electron microscopic observation of both the pores and the morphological changes caused by annealing steps are reported in the present paper. 

Preparation of the membranes. The membranes are prepared by means of the Manjikian s method (10). The three kinds of membranes, unannealed, 50 C- and 85°C-annealed ones, are ready for electron microscopic observations. 

Greenland, D.J., Oades, J.M. Sherwin,T.W. (1968) Electron microscope observations of iron oxides in some red soils. J. Soil Sci. 19 123-126... 

Maeda, Y. Hirono, S. (1981) Electron microscopic observations on the dendrites of synthetic a-FeOOH particles. Japan J. Appl. 

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