Periphereal ring

Bundles of parallel actin filaments with uniform polarity. The microvilli of intestinal epithelial cells (enterocytes) are packed with actin filaments that are attached to the overlying plasma membrane through a complex composed of a 110-kD protein and calmodulin. The actin filaments are attached to each other through fimbrin (68 kD) and villin (95 kD). The actin bundles that emerge out of the roots of microvilli disperse horizontally to form a filamentous complex, the terminal web, in which several cytoskeletal proteins, spectrin (fodrin), myosin, actinin, and tropomyosin are present. Actin in the terminal web also forms a peripheral ring, which is associated with the plasma membrane on the lateral surfaces of the enterocyte (see Figure 5, p. 24). 

Centronuclear myopathy with type 1 fiber hypotrophy is sometimes regarded as a separate entity because many cases show central nuclei only in the hypotrophic type 1 fibers, while the type 2 fibers are morphologically normal. Affected type 1 fibers are even more myotubelike than in other variants of the disorder, with the exception of the severe X-linked form, due to the persistence of a mitochondria-rich core within a peripheral ring of myofibrils. These features are clearly demonstrable using histochemical methods for the localization of SDH activity and myofibrillar ATPase, respectively. 

The degradation of these was described many years ago (Evans et al. 1965), and details have since been added (Figure 8.10a) (van Herwijnen et al. 2003). Phenanthrene is more readily degraded than anthracene, and both can be degraded to o-phthalate. After hssion of the peripheral ring in phenanthrene, several pathways have been demonstrated ... 

There are also certain disubstituted quinacridones which are used commercially. The two peripheral rings in such quinacridone systems (53) are partially chlorinated or methylated. In the sequence 57 - 58 - 53 (p. 455), possible substitution sites on the peripheral rings are indicated by dashes (see also tables of chemical structures in the appendix). 

Fig. 10. Comparison between the 910 to 770 cm -1 emission spectra from NGC 7027 and IRAS 21282 + 5050 with schematic absorption spectra of PAHs in salt pellets. The PAHs shown contain isolated as well as doubly and triply adjacent H atoms on their peripheral rings. (Figure from Ref. [54])... 

Fig. 17.8a,b. Acute ischemic myelomalacia of the lumbar enlargement 3 weeks after onset of symptoms. Contrast-enhanced Tl-weighted images in sagittal and axial orientation at different levels, a Enhancement of the ventral cauda equina (arrow, arrowhead), b Peripheral ring-like enhancement of the affected lumbar enlargement (arrow, arrowhead)... 

A well-known addition to the basic machine is a separate reroll ring beyond the rim of the main disc (see Fig. 3.14). Formed product-size agglomerates are ejected over the rim into this peripheral ring where they are further smoothed and formed into more spherical shapes. A surface layer of fines, such as coke breeze in iron ore green balls or an anti-caking dust to improve storage properties, may be added in the reroll ring. 

The reduction of 41 with potassium, however, proceeded differently62. The peripheral ring current effect of the potassium salt of 412, as reflected in the change in proton chemical shifts, is dramatically enhanced relative to that of the lithium salt (Table 1). The small lithium cation is more effective in attracting the tt-charge and thus in decreasing the ring current effect of the perimeter. 

Peripheral Ring Clomps-Note Slolted Troy, Frictionolly Held to Promote Breathing. 

Figure 133. Diagrams of disc pelletizers equipped with collars or partitions, (a) Basic collar design, (b) collar with rim baffle, (c) concentric vertical partitioning rings, (d) peripheral rings on the rim...

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