Diffraction pattem

Since the (Fen05(0H)6> unit is stable, it has been speculated(8b,17b) that it might also be present in the ferritin core. Since the majority of phosphate in ferritin is adventitious, surface bound and the metallic core can be reconstituted in the absence of phosphate groups with no change in the X-ray powder diffraction pattem(l), replacement of bridging phosphate by bridging carboxylate groups should not influence the three dimensional structure of the core. Calculations show that -409 Fell nnits could fill the apoferritin inner cavity. Further details can be found in reference 17. 

Experimentally, obtain a conventional CBED first by focusing a probe on the TEM specimen. Then move the TEM specimen up or down, a diffraction pattem-like image can be observed in the image mode. Use a selected-area aperture to choose either a BE or a DF spot as shown in the inset of Fig. 5.10c. The height change is determined by the size of the selected-area aperture, such that only one diffraction spot is visible inside the aperture. Finally, switch to the diffraction mode and use the largest condenser aperture or even take the condenser aperture completely out. An example of a LACBED pattern of Si (111) is shown in Fig. 5.10. 

Long-range ordering (crystallinity) in starch granules is demonstrated by x-ray diffraction (Chapter 6). WAXD patterns of starches correspond to one of the two limiting polymorphs (A or B) or the combination C form, the C-pattem being a superposition of A- and B-patterns.28 29 The A form is typical of cereal starches, while... 

Langford, J.I., Louer, D., and Scardi, R, Effect of a crystallite size distribution on x-ray diffraction line profiles and whole-powder-pattem fitting, J. Appl. Crystal-logr, 33, 964, 2000. 

Fu Y, Busing WR, Jin Y, Affholter KA, Wunderlich B (1993) Poly(ethylene Tereph-thalate) Fibers 1. Crystal Structure and Morphology Studies with Full-pattem X-ray Diffraction Refinement. Macromolecules 26 2187-2193. 

Organic molecules such as 1-butanol form a similar complex with amylose in which the 1-butanol molecules are complexed in the hydrophobic interior of the helix. These complexes have crystalline properties and produce X-ray diffraction patterns called a V-pattem [19] (see Fig. 6.6). Electron microscopy and electron diffraction studies have indicated that the complex is a folded helical chain with a lamellar structure [20-24]. The helical chain folds every 100 A, giving an antiparallel structure in which the helices are 13 A in diameter (see Fig. 6.4C). 

Native starch granules give distinct X-ray diffraction patterns of three types [30c,30d] an A-pattem characteristic of cereal starches such as maize, wheat, and rice starches, a B-pattem characteristic of tuber, fruit, and stem starches such as potato, banana, and sago starches and a C-pattem that is obtained from some starches and is intermediate between the A- and B-pattems and may be due to mixtures of A-type and B-type granules (see Fig. 6,6), X-ray diffraction indicates that the starch granules have crystalline properties. However, they are only partly crystalline and vary in their degree of crystallinity [31]. Waxy starches that are 100% amylopectin showed a crystallinity of 40%, and high-amylose starches showed a crystallinity of only 15%. 

Combining silk films with nano- and micro-patteming technologies can also bring some optical properties to silk films. This is an approach similar to lithography. The final products are usually in the form of optical lenses, a microlens array, a two-dimensional diffractive optical element, a diffraction grating, and a white-light... 

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