Semi-crystalline array

The answer is B. Saturated fatty acids and trans fatty acids are structurally similar their hydrocarbon tails are relatively linear. This allows them to pack tightly together in semi-crystalline arrays such as the membrane bilayer. Such arrays have similar biochemical properties in terms of melting temperature (fluidity). Although some of the other properties listed are also shared by saturated and trans fats, they are not thought to account for the tendency of these fats to contribute to atherosclerosis. 

As with other natural fibres, silk has a hierarchical microstructure - about five anti-parallel (f-sheets, each with around 12 chains, aggregate to form parallel, crystalline microfibrils (approximately 10 nm in diameter), bundles of which make up fibrillar elements (roughly 1 p,m across), which in turn associate to comprise the individual fibroin filaments (7-12 xm) at each level of organisation, the ordered elements are embedded within amorphous matrices derived from the non-crystalline components. Once again, then, the behaviour of the structural composite can be understood in terms of the semi-crystalline array of its component parts. 

What (xvii) shows is that the Bessel function terms provide single-crystal-like diffraction and all other Bessel terms continuous intensity. Although this kind of array is not the only one for which Bragg and continuous intensity both occur in the same pattern, it is mainly for this that the unfortunate term "semi-crystalline" has sometimes been used. Examples are C-DNA (9,10), ribosomal RNA fragments (11). Fig. 4 shows an example of the diffraction from such an array of molecules. The helices in this case are 12-fold therefore has large values only for small values of Si. It follows that the Bragg diffractid is confined to the center of the pattern. 

In Section 9.3 we present experimental studies of plastic deformation in two semi-crystalline polymers, HDPE and Nylon-6, both in tension and in plane-strain compression flow, from initial spherulitic morphologies to large plastic strains. In these studies, the evolving morphological alterations were monitored closely by a complementary array of techniques involving light microscopy and X-ray diffraction and scattering both in the crystalline and in the amorphous components. 

Block copolymers such as polystyrene-fc/ocfc-polybutadiene-b/ock-polystyrene, or those containing the hydrogenated (saturated) version of polybutadiene, have been successfully combined with semi-crystalline nylons and polyesters to make extremely tough, leathery compositions. The above types of block copolymers can also be combined with ionomers to make an interesting array of materials. Also, two ionomers can be combined together. ... 

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