Wide-angle X-ray diffraction patterns

Figure 1. Wide angle X-ray diffraction pattern from PET films exposed to DMF at various temperatures for 15 min.

Fibrinogen is a fibrous protein that was first classified with keratin, myosin, and epidermin based on its 5.1 A repeat in wide-angle X-ray diffraction patterns (Bailey et al., 1943), which was later discovered to be associated with the Q-helical coiled-coil structure. It is a glycoprotein normally present in human blood plasma at a concentration of about 2.5 g/L and is essential for hemostasis, wound healing, inflammation, angiogenesis, and other biological functions. It is a soluble macromolecule, but forms a clot or insoluble gel on conversion to fibrin by the action of the... 

Fig. 16 Wide-angle X-ray diffraction patterns showing the reappearance of the three crystalline phases namely monoclinic, open-orthorhombic and dense-orthorhombic, during increase in pressure at room temperature...

Figure 8. Wide-angle x-ray diffraction patterns of the (a) oriented and (b) unoriented portions of the quenched sample...

The structure of truly crystalline regions of a polymer may be determined from wide-angle X-ray diffraction patterns. In this way the unit cell dimensions and molecular configurations have been obtained for all the common polymers. In general, the molecules of the crystalline phase adopt an extended zigzag or helical conformation and lie parallel to each other. 

All of the invertebrate collagens which have been examined have yielded the typical collagen wide-angle X-ray diffraction pattern, and electron micrographs of the fibers show, with the exception of Physalia float and Metridium body wall, the characteristic 600-700 A axial period (Gross et al., 1958). 

Fio. 8. Wide-angle X-ray diffraction patterns of collagen from rat tail tendon (o) unstretched (h) stretched 8%. (From Randall, 1954.)... 

Recent interpretations of wide-angle X-ray diffraction patterns have led to a three-chain structure for collagen, at least in the ordered interband regions. This strongly suggested that a three-stranded structure should exist in the collagen monomer as well. Several lines of evidence support this view ... 

Figure 4. Wide angle x-ray diffraction patterns of newborn rat stratum corneum with beam normal and parallel (edge) to the corneum plane (13)...

The wide angle x-ray diffraction pattern of undeformed corneum exhibits diffuse halos at 4.6 A and 9.8 A common to proteins (Figure 4). The lack of the 5.1-A reflection characteristic of alpha-keratin structures in undeformed comeum suggests that the protein is considerably less oriented and perhaps of a lower alpha content than wool. This is supported by the fact that the 5.1-A reflection begins to appear in samples of comeum which were hydrated and stretched to 100% or more (Figure 6) and allowed to dry in the extended state. The increased orientation of the lipid reflections in the stretched sample demonstrates further their association with the orienting protein fibrils. 

Fig. 14 Wide Angle X-ray Diffraction Patterns of (a) as-received and (b) IC coalesced nylon-6 [23,92-94]...

Figure 9. Wide-angle x-ray diffraction pattern of a stretched fiber of a 57% 4GT/PTMEG-T copolyester...

Figure 6. Wide angle x-ray diffraction patterns (top) and small angle x-ray scattering patterns (bottom) of EO-ls-EO 2 film...

X-Ray Orientation Angle Wide angle X-ray diffraction patterns were obtained with a Warhus pinhole camera and Phillips generating unit No. 12045 having a copper fine focus diffraction tube and a nickel 8 filter. The distance from sample to film was 50 mm. The arc length In degrees between the half-maximum Intensity points of a principal equatorial diffraction spot Is reported as the orientation angle of the sample. 

FIGURE 3.20 Wide-angle x-ray diffraction patterns of ZNPP and MiPP samples (a) ZNPP, (b) MiPP, (c) MiPP annealed at 143°C for 2 min. (From Bond, E.B. Spruiell, J.E. ANTEC, Europe, 1997, 388.)... 

Small-angle x-ray diffraction patterns of porcupine quill fiber saturated with water show that the microfibrils and matrix have increased in volume 11 and 53%, respectively, compared with those of the dry quill [135,293]. Wide-angle patterns of keratin fibers show [135,293] that between 0 and 80% RH there is a 4-5% increase in the distance between the a-helices, compared with a 9% increase in the diameter of the fiber. When the RH is increased to 100%, there is no further increase in the distance between the a-helices, but the increase in the diameter of the fiber is 16%, compared with that of the dry fiber. The a-helices are present in the microfibrils, and they represent about half the total mass of the microfibrils. The wide-angle x-ray diffraction patterns may therefore imply that the extra water absorbed between 80 and 100% RH is absorbed by the matrix. 

Poly aniline (emeraldine salt) can be recovered in partially crystalline form from solutions in sulfuric acid. This is demonstrated by the wide-angle X-ray diffraction pattern of such a poly aniline film, shown as the upper solid curve in Figure la. Essentially identical... 

The unit cell parameters can be determined from the wide angle X-ray diffraction patterns of the single crystals, films, or fibers. PBS has two crystalline modifications a and P form, depending on the crystallization conditions. The a form appears when PBS is crystallized from a quiescent melt, whereas the P form occurs under mechanical stress. Both of the modifications belong to the monoclinic system with the space group of P2/n. In both cases, the unit cell contains two molecular chains ... 

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