Thin sections cutting

Thin sections cut with a diamond knife microtome can be of great advantage in locating regions of catalyst where important chemical or structural changes take place during reaction. Comparison of equivalent areas of fresh and deactivated catalyst can be a difficult problem if the catalyst support does not have a uniform microstructure as in carbon supports produced from plant materials. Even when specimen selection and preparation are adequate, it may be difficult to know upon which image features to place the electron beam to solve the problem at hand. 

The cell walls of the vessels in Persea wood have reacted to the coalifying processes in a way that is different from the response of the fiber-tracheid walls, even though the two wall types may lie in juxtaposition. Microscopic study of thin sections, cut on a microtome, show that the vessel walls are yellow-tan in color, anisotropic, and morphologically intact though often deformed. In contrast, the fiber-tracheid walls have been converted to a yellow-brown to orange-brown, isotropic material that exhibits little of the original... 

High resolution transmission electron microscopy (TEM) (Jeol lOOCX) was employed to determine the size of the metal particles on the surface of the catalyst support, and the composition of individual metal particles was ascertained (for thin sections cut with an ultramicrotome) using a field-emission scaiming transmission electron microscope (STEM) (VG HB 501) (at 1.5 mm resolution) and an energy dispersive X-ray (EDX) analyser. The metal loading of catalysts was determined by ICP-AES (Spectro D), following dissolution in concentrated hydrochloric and sulphuric acids. Direct analysis of aqueous samples taken from the reaction medium, using the same analytical technique, allowed the corrosion of metallic components from the catalyst surface to be studied. 

Figure 15. Optical orientation of a model mica crystal showing the random position of the thin section cut across cleavage and used for microXANES measurements (Dyaret al. 2001).

Compositionally distinct material observed in the cores of some migmatite zone monazite crystals (e.g.. Figs. 15g,h,i) could readily be interpreted as representing the initially-formed monazite core. However, Pyle et al. (2001) have suggested that this texture, in some instances, may arise from an extremely irregular crystal shape and the orientation of the thin section cut through the crystal (Fig. 16). Monazite at low grades is... 

Analysis of yielding at a notch (a) shear band patterns seen in a thin section cut from a polycarbonate specimen (b) slip line field pattern for yielding (c) Mohr circle diagram for the states of stress at points A and B in (b) (d) stress components on the surface of the prism marked out by neighbouring a and j3 slip lines. 

Figure 19.1 Thin sections cut from specimens deformed just beyond the yield point in plane-strain compression viewed through crossed polarizers in the optical microscope, (a) Microshear bands formed in polystyrene, (b) Diffuse shear bands formed in poIy(methyl methacrylate). (Reproduced with permission from ref. 2.)...

Figure 19 Transmission electron micrographs of thin sections cut from ABS materials. The rubbery domains appear darker, (a) An ABS material prepared by bulk polymerization showing the characteristic salami-like morphology of the toughening particl which contain several SAN domains within the rubber, (b) ABS materials prepared by emulsion polymerization showing cote-shell partides (i) widi and (ii) widiout subinclusions. (Reproduced with permission from ref. 29.)...

Figure 1 Polarizing micrographs of thin sections cut (a) perpendicular (b) parallel to the flow direction (MD). (TI> transverse direction, ND thickness direction).

Optical microscopy can be used as a complementary techihque to small-angle light scattering for the determination of spherulite dimensions. However, in optical microscopy, when the diameter of the spherulites is substantially less than the thickness of the film it is difficult to distinguish between spherulites that overlap within the plane of the specimen. On the other hand, if a very thin section cut from a thicker sample is examined by optical microscopy, a relatively small proportion of the spherulites observed will contain the equatorial plane representative of the true spherulite dimensions. 

For holes in thin sections, circle cutters, or drills which only cut the circumference and eject a round thin plug of material, will often be preferred for production. 

In this example a polymer laminate film (for packaging) was examined, which was composed of nine layers (see Table 2), by both FTIR imaging and Raman line scan. For the IR measurements thin sections (5 pm) were cut. The central ethylene/vinyl acetate (EVA) copolymer layer is very soft, and holes can be seen in the visible image (Figure 12). 

Section with glass knives or diamond knife and ultramicrotome. Note Usually thick sections (1 pm) are cut, affixed to glass microscope slides, and stained 5-15 min at 40-50°C with toluidine blue solution (1 g toluidine blue and 1 g of sodium borate in 100 mL H20), The block is then refaced so that the trapezoid encompasses the desired tissue. Thin sections of gray, silver, or gold interference colors are cut. 

Embed the dehydrated samples in epoxy resin (Quetol 653), cut into thin sections, stain with 4% uranyl acetate and 0.4% lead citrate, and examine with a Jeol 1200EXS electron microscope. 

Fig. 9 Electron micrograph of an ultramicrotome-cut thin section of a layer of paint, seen parallel to the orientation of acicular pigment particles and perpendicular to the surface of the layer.

Fig. 48 Electron micrographs of ultramicrotome-cut thin sections of a nonirradiated and an irradiated layer (alkyd-melamine resin baking enamel) containing Pigment Violet 19, y-modification. Above irradiated, below nonirradiated.

Fig.84 Influence of different dispersing conditions on the degree of dispersion of Pigment Yellow 17 in a sheet offset varnish and on the gloss of prints which were produced from this system. Images of ultramicrotome-cut thin sections of the printed layers taken with a transmission electron microscope.

These days the most common method employed for the generation and detection of ultrasound utilises the piezoelectric properties of certain crystals one of which is quartz [3]. A simplified diagram of a crystal of quartz is reproduced (Fig. 7.3) which shows three axes defined as x, y and z. If a thin section of this crystal is cut such that the large surfaces are normal to the x-axis (x-cut quartz) then the resulting section will show the following two complementary piezoelectric properties ... 

Specimens were post-fixed in 1% OSO4 in sodium cacodylate buffer, dehydrated in ascending alcohol solutions, and embedded in Epon LX 112. Semi-thin sections (1.0 pm thickness) were cut with a diamond knife and stained with Richardson s dye (contains methylene blue) or PAS-reagent. Micrographs were made with an Olympus New Vanox microscope. 

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