Structural anisotropy

The ideas developed in this chapter are descriptive of shock waves in fluids. Solids have many significant features that distinguish them from liquids and gases, such as shear strength, polymorphic phase transformations, heterogeneous structure, anisotropy, and viscoplastic behavior. The influences of these special properties of solids on shock compression are the topics of several of the other chapters, and for the most part are ignored in this introduction to the basic principles of shock compression. 

High temperature superconductors (HTS), 23 814, 826, 829. See also Anisotropic HTS HTS entries applications of, 23 852-872 layered, 23 827, 840 magnetic phase diagram of, 23 838-842 p- and n-type, 23 838 structural anisotropy and fluxon line fragmentation in, 23 841 thallium- and mercury-based, 23 848-850... 

It was thus possible to extend point data to homogeneous areas and to determine with a higher degree of precision the nature of the anomalies revealed, whether due to structural anisotropy or to the presence of organic fluids in the subsurface. 

CASE 2 - Evaluation of the importance of structural anisotropies (fractures, faults, cataclastic bands) and their persistence (horizontal and vertical) measured at the surface (structural-geological survey) and their mapping (integrated evaluation of geophysical data and structural-geological data)... 

Diffusion is defined as the random translational motion of molecules or ions that is driven by internal thermal energy - the so-called Brownian motion. The mean movement of a water molecule due to diffusion amounts to several tenth of micrometres during 100 ms. Magnetic resonance is capable of monitoring the diffusion processes of molecules and therefore reveals information about microscopic tissue compartments and structural anisotropy. Especially in stroke patients diffusion sensitive imaging has been reported to be a powerful tool for an improved characterization of ischemic tissue. 

Aromatic polyimide films that are spin-coated or solution-cast with thicknesses under 15 jm exhibit structural anisotropy in the condensed state. This anisotropy is associated with the tendency of the chains to align parallel to the substrate surface, undergoing what is described as in-plane orientation. 

The structural anisotropy in crystalline or structurally ordered BPDA-PFMB films was studied in this laboratory with wide-angle X-ray diffraction (WAXD) methods. In brief, WAXD experiments were designed to examine both the reflection and transmission modes of thin-fihn samples. In addition, uniaxially oriented polyimide fiber WAXD patterns were obtained to aid in the identification of the film structure. The film WAXD pattern obtained from the reflection mode corresponded well to the fiber pattern scanned along the equatorial direction (Figure 16.3), " which indicates that the reflection mode pattern represents the (hkQ) diffractions. On the other hand, as shown in Figure 16.4, the (001) diffractions were predominant in the film WAXD pattern obtained via the transmission mode. This pattern corresponded to the fiber pattern scanned along the meridian direction. These experimental observations clearly indicate that the c-axes of the crystals are preferentially oriented parallel to the film surface however, within the film, they are randomly oriented. 4.2 5 j( should be pointed out that the WAXD experiments are only sensitive to crystalline or ordered structures in polyimide films. They do not provide any information on the amorphous regions. 

TABLE 7. Structural anisotropy of stilbene and tolane based azomethines ... 

This survey deals with the fundamental morphological parameters of foamed polymers including size, shape and number of cells, closeness of cells, cellular structure anisotropy, cell size distribution, surface area etc. The methods of measurement and calculation of these parameters are discussed. Attempts are made to evaluate the effect and the contribution of each of these parameters to the main physical properties of foamed polymers namely apparent density, strength and thermoconductivity. The cellular structure of foamed polymers is considered as a particular case of porous statistical systems. Future trends and tasks in the study of the morphology and cellular structure-properties relations are discussed. 

As shown by Karapetyan the structural anisotropy coefficients differ very... 

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