Single-Layered Configurations

Stiffnesses for single-layered configurations are treated first to provide a baseline for subsequent discussion. Such stiffnesses should be recognizable in terms of concepts previously encountered by the reader in his study of plates and shells. Next, laminates that are symmetric about their middle surface are discussed and classified. Then, laminates with laminae that are antisymmetrically arranged about their middle surface are described. Finally, laminates with complete lack of middle-surface symmetry, i.e., unsymmetric laminates, are discussed. For all laminates, the question of laminae thicknesses arises. Regular laminates have equal-thickness laminae, and irregular laminates have non-equal-thickness laminae. 

The special single-layered configurations treated in this section are isotropic, specially orthotropic, generally orthotropic, and anisotropic. The generally orthotropic configuration cannot, of course, be distinguished from an anisotropic layer from the analysis point of view, but does have only the four independent material properties of an orthotropic material. 

For a single isotropic layer with material properties, E and v, and thickness, t, the laminate stiffnesses of Equation (4.24) reduce to 

there is no coupling between bending and extension of a single isotropic layer. Also note that 

For a single specially orthotropic layer of thickness, t, and lamina stiffnesses, Qjj, given in Equation (2.61), the laminate stiffnesses are 

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Suppression of the aggregate emission is possible in two quite different ways. At first, the aggregate emission could be almost completely shut out by simply diluting the LPPP 12 with a matrix polymer. LEDs with 1% LPPP 12 in poly(9-vinylcarbazole) PVK as emitter material are characterized by a pure blue light emission with a quantum efficiency of ca. 0.15% in single-layer configuration (lTO/1% LPPP 12 in PVK/Ca) 135],... 

Mizuta et al. (1993) have reported that a single-layer photoreceptor containing 9-isopropylcarbazole-3-carbaldehyde-N,N-diphenylhydrazone is fatigued on exposure to ultraviolet radiation. The results were interpreted by a mechanism where radiation induces isomerization of the anti- to the -isomer. The latter has a lower ionization potential and is a hole trap. In the single-layer configuration, hole trapping near the free surface results in the creation of volume space charges, which cause decreased sensitivity. 

For the use in catalysis, characterization of G materials requires the combination of typical imaging techniques to prove the 2D morphology and the single layer configuration of G, plus characterization of the activity of the active sites. For characterization of G materials the information provided by, at least, four different techniques, namely Raman and XPS, electron microscopy, and atomic force microscopy (AFM) are required. Raman spectroscopy should show the three 2D, G, and D bands present... 

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