Fibers electron micrographs

Fig. 10. A dark field (DF) transmission electron micrograph showing interface in a continuous fiber (F) a-Al202 (F)/Mg alloy (ZE41A) matrix (M) within...

Fig. 7. Electron micrographs showiag (a) an untreated wool fiber and (b) a wool fiber treated with cblorine-Hercosett.

Fig. 8. Electron micrograph of Merino wool fibers in a fabric that have been treated with a typical shrink-resistance polymer, showing fiber—fiber bond...

Fig. 2. Electron micrographs of asbestos fibers (a) cbrysotile (b) crocidolite.

Fig. 5. Scanning electron micrographs of hoUow fiber dialysis membranes. Membranes in left panels are prepared from regenerated cellulose (Cuprophan) and those on the right from a copolymer of polyacrylonitrile. The ceUulosic materials are hydrogels and the synthetic thermoplastic forms a microreticulated open cell foam with a tight skin on the inner wall. Pictures at top are membrane cross sections those below are of the wall region. Dimensions as indicated.

Figure 3.14 Sickle-cell hemoglobin molecules polymerize due to the hydrophobic patch introduced by the mutation Glu 6 to Val in the P chain. The diagram (a) illustrates how this hydrophobic patch (green interacts with a hydrophobic pocket (red) in a second hemoglobin molecule, whose hydrophobic patch interacts with the pocket in a third molecule, and so on. Electron micrographs of sickle-cell hemoglobin fibers are shown in cross-section in (b) and along the fibers in (c). [(b) and (c) from J.T. Finch et al., Proc. Natl. Acad. Set. USA 70 718-722, 1973.)...

The two-phase morphologic structure has also been observed in the electron micrographs of polyethylene films and fibers obtained by orientational crystallization16 in which the amount of ECC was approximately 15 to 20% (the fraction of ECC in Porter s samples47 was 17 to 25%). 

Fig.1. Electron micrograph of a mast cell in human heart tissue. The cytoplasm contains numerous secretory granules. The mast cell is adjacent to a coronary blood vessel, surrounded by collagen fibers and close to a myocyte. Uranyl acetate and lead citrate stained. Orig. magnif. lO.OOOx. 

Figure 11.7 Scanning electron micrograph of pentacene fibers prepared by dewetting of a hot trichlorobenzene solution using the roller apparatus. The fibers are aligned along the rolling direction (reprinted with permission from Ref 71). The scale bar is 5 pm.

Fig. 10. Scanning electron micrograph of a fracture surface parallel to the direction of extrusion of an extrudate of a 45 55 PS-HDPE blend with a viscosity ratio p 1. Fibrous PS is shown at different stages of breakup the diameter of the largest fiber is about 1 pm (Meijer el til., 1988).

Muhlethaler, K. Electron Micrographs of Plant Fibers. Biochem. bio-physica Acta 3, 15 (1949). 

FIGURE 4-4 Electron micrograph of a single peripheral nerve fiber from rabbit. Note that the myelin sheath has a lamellated structure and is surrounded by Schwann cell cytoplasm. The outer mesaxon (arrowhead) can be seen in lower left. AX, axon. (Courtesy of Dr Cedric Raine.)... 

The nervous system contains an unusually diverse set of intermediate filaments (Table 8-2) with distinctive cellular distributions and developmental expression [21, 22]. Despite their molecular heterogeneity, all intermediate filaments appear as solid, rope-like fibers 8-12 nm in diameter. Neuronal intermediate filaments (NFs) can be hundreds of micrometers long and have characteristic sidearm projections, while filaments in glia or other nonneuronal cells are shorter and lack sidearms (Fig. 8-2). The existence of NFs was established long before much was known about their biochemistry or properties. As stable cytoskeletal structures, NFs were noted in early electron micrographs, and many traditional histological procedures that visualize neurons are based on a specific interaction of metal stains with NFs. 

Figure 5.5 Computer-generated model of quadruple helix structures made of D-Glu-8 (1) based upon image-processed electron micrograph of helical fibers. Reprinted with permission from Ref. 35. Copyright 1993 by the American Chemical Society.

Figure 5.8 Electron micrographs of (a) right-handed helices and tubules from A-dodeca-5,7-diyne-D-galactonamide (10) and (b) braided fibers from A-dodeca-5,7-diyne-L-arabonamide (11). Reprinted with permission from Ref. 47. Copyright 1994 by the American Chemical Society.

The muscle fibrils are embedded in sarcoplasm, each individual fibril showing the banding pattern of the whole fiber (Bowman, 1840). Myosin could be extracted from muscle with strong salt solutions. From the altered appearance of the bands after extraction it was suggested that this protein was a major component of the A bands (Kuhne,1864 Danilewsky, 1881). The localization of myosin in the A bands and of actin in the I bands was convincingly shown by Jean Hanson and Hugh Huxley (1954-1955) in electron micrographs of transected fibers and confirmed after selective extraction to remove myosin (Hasselbach, 1953 Hanson and H.E. Huxley, 1953-1955). 

Fig. 8.1 Electron micrographs of different nanocarbon composite types (top) and their schematic representation (bottom). The nanocarbons can be dispersed as a filler (left), combined with macroscopic fibers in a hierarchical composite (middle), or assembled as a continuous nanostructured fiber (right). Micrographs from references [7, 8, 9], with kind permission from Elsevier (2010, 2008, 2009).

Fig. 8.9 Different methods for spinning CNT fibers and scanning electron micrographs of representative samples, (a) Wet spinning of nanocarbons dispersed in liquid, (b) drawing from a forest of aligned CNTs and (c) direct spinning from the gas phase during CNT synthesis by CVD. Images from references [53,59, 60, 61,62], With kind permission from AMS (2000, 2013), Elsevier (2007, 2011), Wiley (2010).

FlC. 3. Electron micrographs of assembled histone fibers (a) H4, acid-extracted (b) H3-H4, acid-extracted (c) H3-H4, salt-extracted (d) H2AH2BH3H4, acid-extracted (magnification x 78,000). 

Structural studies were also performed on other histone fibers, in particular H3-H4 fibers and fibers prepared from all four core histones mixed in equimolar ratios. Bundles of fibers from both systems have also been obtained. The optical diffraction patterns from electron micrographs again showed dominant axial spacings of 55, 37, and 27 A, indicating a fundamental similarity of organization for all the histone fibers (Sperling and Wachtel, 1979). 

Euchromatin generally corresponds to looped 30-nm fibers. Heterochromatin is more highly condensed. Figure 1-1-14 shows an electron micrograph of an interphase nucleus containing euchromatin, heterochromatin, and a nucleolus. The nudeolus is a nuclear region spedalized for ribosome assembly (discussed in Chapter 3). 

With the demise of the uniform fiber model in 1974, it became necessary to devise other models to account for the early electron micrographs of chromatin fibers and the X-ray diffraction studies (see Ref. [1], Chapter 1). Two models appeared in 1976, and were the major contenders for consideration in 1978. The superbead model of Franke et al. [36] envisioned the chromatin fiber as a compaction of multi-nucleosome superbeads . The solenoid model of Finch and Klug [37] postulated a regular helical array of nucleosomes, with approximately six nucleosomes per turn and a pitch of 10 nm. Although a number of competing helical models appeared in the 1980s (see Ref. [1], Chapter 7) the solenoid model remains a serious contender to this day. Structural details of this model, such as the precise disposition of linker DNA, are still lacking. 

Fig. 2.4 Chrysotile asbestos sectioned perpendicular to the fiber axis. Electron micrograph showing typical lattice images of the layers of this serpentine mineral rolled into hollow cylinders (fibrils).

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