Transversal structure

On either type of diffraction pattern the individual diffraction spots can be used to calculate spadngs between planes of equivalent structure in the specimen. The spots often occur in row or layer lines as shown in Fig. 2. Particular importance attaches to the layer lines, which are expected to cross the central row line (meridian) at regular intervals and may be numbered (indexed) according to their distance from the central layer line (equator). The separation between layer lines usually permits unequivocal establishment of the size of the axial period of the fibril s structure, i.e. the distance between equivalent locations along the fibril. Row lines can be used to determine structure transverse to the fibril axis, but unless a large number of row lines are available the study of transverse structure is limited. 

This chapter has been both a retrospective of our work and an overview of some studies which have been conducted since about 1980 on the negative effect during shear of lyotropic PLCs and the formation of band structures transverse to the shearing direction upon cessation of shear. The two phenomena are a manifestation of (1) liquid crystalline order, how this order is affected by forces imposed on molecules and domains during shear, and (2) how the stored energy relaxes after... 

Osmium tetroxide stained electron micrographs of polystyrene-Z>/ucA -polybutadiene-Z /ocA -polystyrene block copolymer produced by extrusion. (a) Micrograph demonstrating the orientation of the styrene cylinders in the direction of the extrusion (direction A in the schematic) and (b) shows a close-packed structure transverse to the extrusion direction (direction B in the schematic). Scale bar = 1 pm. 

Etching has been used to reveal structures in polymer fibers [179,180], polymer blends [181,182] and in bulk polymers, such as PET [183] and PE [184]. Periodic structures were seen to develop on argon plasma etched, oriented materials, such as nylon and PET, thought to be characteristic of the fold period [185]. Such structures were also shown for ion etched (argon) fibers [186]. Fine scale structures were observed for etched polyamide [187], PET [19,188] and aramid fibers [187] which showed ripple structures transverse to the fiber axis. 

Figure 14a shows a two-layer bimorph cantilever structure (transverse-effect bimorph structure). IViro piezoelectrk polymer films with the same polarization direction arc attached altogether by adhesive. Oiw end of the piece is fixed and the other is free. When electric fields with opposite directioas (to the polarization direction) are applied to them, one layer tends to elongate and the other layer to shrink. The bimoiph deflects because of the opposite stresses, and a large elastic displacement can be obtained at the free end. Let the radius of curvature of the deflected bimorph shown in Figure 14a be /lo the... 

Under this programme 25% of the stiffeners and adjacent plate material in bulk carriers will be examined with thickness measurements being taken at upper, lower and mid points in both face and web plates of the stiffeners and associated end brackets. The extent of thickness measurement applied to transverse bulkheads has also been increased. In addition. Classification has revised the scantling requirements for new buildings to nominate thicker material in the bottom structure and at the transverse watertight bulkheads of the No 1 cargo holds. 

In Fig. III-7 we show a molecular dynamics computation for the density profile and pressure difference P - p across the interface of an argonlike system [66] (see also Refs. 67, 68 and citations therein). Similar calculations have been made of 5 in Eq. III-20 [69, 70]. Monte Carlo calculations of the density profile of the vapor-liquid interface of magnesium how stratification penetrating about three atomic diameters into the liquid [71]. Experimental measurement of the transverse structure of the vapor-liquid interface of mercury and gallium showed structures that were indistinguishable from that of the bulk fluids [72, 73]. 

The actual structure at a vapor-liquid interface can be probed with x-rays. Rice and co-workers [72,73,117] use x-ray reflection to determine the composition perpendicular to the surface and grazing incidence x-ray diffraction to study the transverse structure of an interface. In a study of bismuth gallium mixtures. 

Iditional importance is that the vibrational modes are dependent upon the reciprocal e vector k. As with calculations of the electronic structure of periodic lattices these cal-ions are usually performed by selecting a suitable set of points from within the Brillouin. For periodic solids it is necessary to take this periodicity into account the effect on the id-derivative matrix is that each element x] needs to be multiplied by the phase factor k-r y). A phonon dispersion curve indicates how the phonon frequencies vary over tlie luin zone, an example being shown in Figure 5.37. The phonon density of states is ariation in the number of frequencies as a function of frequency. A purely transverse ition is one where the displacement of the atoms is perpendicular to the direction of on of the wave in a pmely longitudinal vibration tlie atomic displacements are in the ition of the wave motion. Such motions can be observed in simple systems (e.g. those contain just one or two atoms per unit cell) but for general three-dimensional lattices of the vibrations are a mixture of transverse and longitudinal motions, the exceptions... 

The electrical-resistance method involves passing an electric current through the structure and exploring the surface with voltage probes. Flaws, cracks, or inclusions will cause a disturbance in the voltage gradient on the surface. Railroads have used this method for many years to locate transverse cracks in rails. 

The transverse modulus is lower partly because the cell wall is less stiff in this direction, but partly because the foam structure is intrinsically anisotropic because of the cell shape. When wood is loaded across the grain, the cell walls bend (Fig. 26.5b,c). It behaves like a foam (Chapter 25) for which... 

Hamada, T., Nishida, T., Furuyama, M. and Tomioka, T., Transverse structure of pitch fiber from coal tar mesophase pitch. Carbon, 1988, 26(6), 837 841. 

In hardwoods, morphological structural elements in longitudinal series comprise the segmented structure termed vessel . Vessels, which are exposed in transverse section, constitute about 10-46% of the stem volume in deciduous hardwoods and are cells of relatively large diameters (50-300 p.m). Vessels have in short the appearance of open vertical tubes within the wood structure because their end walls have partially dissolved. By comparison, the hardwood vessel diameter can be as much a 10 times the diameter of a softwood fiber. 

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