Oriented Systems

Those, on industrial applications orientated systems, are acoustic emission and the temperature analysis of the casting. Realizing this conception (fig. 2) will enable to develop a process parameter control and consequently to stabilize the casting process. 

In oriented systems (fibres or stretched films), the scattered image often appears as a two-bar or a four-point pattern with the scattering maximum at or near the meridian (fibre axis). The one-dimensional scattered intensity along the meridian must be calculated by the projection method using the following fonnalism... 

Kale, L., Krishnan, S. Charm-t—1- A Portable Concurrent Object Oriented System Based on C-(—1-. In Proceedings of the Conference on Object Oriented Programming Systems, Languages and Applications. A. Paepcke, editor. ACM Press, New York, N.Y., 1993. 

Program systems for computer-assisted organic synthesis (CAOS) have been under development since the early 1970s [27]. The program systems for computer-assisted synthesis planning can be subdivided into two groups information-oriented and logic-oriented systems [28]. 

Information-oriented systems are based on a Hbrary of known retro-reactions which have been collected and evaluated by a group of chemists while coding them in electronic form. In addition, information on the scope and the expected yield under various conditions, as well as a strategic merit, is usually stored. 

Some object-oriented systems also support the notion of subobjects. This faciUtates the representation of stmctural relationships. For example, the objects IMPELLER and LINING can be made subobjects of a REACTOR object, to represent the stmctural components of the reactor. 

In object-oriented systems, the notion of inheritance is important. Inheritance means that a property of a class is automatically acquired by subclasses and objects of that class. Eor instance, having defined all the classes and objects Hsted above, if the property TIMESTAMP has to be added to all process data objects, one simply has to add it to the class PROCESS DATA. This modification would be automatically reflected in all subclasses and objects. 

The development of the internal orientation in formation in the fiber of a specific directional system, arranged relative to the fiber axis, of structural elements takes place as a result of fiber stretching in the production process. The orientation system of structural elements being formed is characterized by a rotational symmetry of the spatial location of structural elements in relation to the fiber axis. Depending on the type of structural elements being taken into account, we can speak of crystalline, amorphous, or overall orientation. The first case has to do with the orientation of crystallites, the second—with the orientation of segments of molecules occurring in the noncrystalline material, and the third—with all kinds of structural constitutive elements. 

These two different approaches for attaining an oriented state in flexible-chain and rigid-chain polymers indicate that the fundamental property of macromolecules - their flexibility - is of great importance to the orientation processes. However, the mechanism of the transition into the oriented state and the properties of highly oriented systems exhibit many features characteristic of both rigid- and flexible-chain polymers. 

According to Hosemann-Bonart s model8), an oriented polymeric material consists of plate-like more or less curved folded lamellae extended mostly in the direction normal to that of the sample orientation so that the chain orientation in these crystalline formations coincides with the stretching direction. These lamellae are connected with each other by some amount of tie chains, but most chains emerge from the crystal bend and return to the same crystal-forming folds. If this model adequately describes the structure of oriented systems, the mechanical properties in the longitudinal direction are expected to be mainly determined by the number and properties of tie chains in the amorphous regions that are the weak spots of the oriented system (as compared to the crystallite)9). 

In this review the definition of orientation and orientation functions or orientation averages will be considered in detail. This will be followed by a comprehensive account of the information which can be obtained by three spectroscopic techniques, infra-red and Raman spectroscopy and broad line nuclear magnetic resonance. The use of polarized fluorescence will not be discussed here, but is the subject of a contemporary review article by the author and J. H. Nobbs 1. The present review will be completed by consideration of the information which has been obtained on the development of molecular orientation in polyethylene terephthalate and poly(tetramethylene terephthalate) where there are also clearly defined changes in the conformation of the molecule. In this paper, particular attention will be given to the characterization of biaxially oriented films. Previous reviews of this subject have been given by the author and his colleagues, but have been concerned with discussion of results for uniaxially oriented systems only2,3). 

Despite its weakness, the anisotropy of the g tensor of iron-sulfur centers can be used to determine the orientation of these centers or that of the accommodating polypeptide in relation to a more complex system such as a membrane-bound complex. For this purpose, the EPR study has to be carried out on either partially or fully oriented systems (oriented membranes or monocrystals, respectively). Lastly, the sensitivity of the EPR spectra of iron-sulfur centers to structural changes can be utilized to monitor the conformational changes induced in the protein by different factors, such as the pH and the ionic strength of the solvent or the binding of substrates and inhibitors. We return to the latter point in Section IV. 

G. Schonhense and J. Honnes, Photoionization of oriented systems and circular dichroism. In U. Becker and D. A. Shirley (eds.), VUVand Soft X-Ray Photoionization, Chapt. 17, Plenum, New York, 1996, pp. 607-652. 

Similar to attributes, procedures can be inherited by child frames when inheritance is supported. Object-oriented programming enormously enlarges the flexibility of frame-based systems. A disadvantage is, however, that it results often in unclear and intractable reasoning structures. Table 43.2 shows the small rule base of Fig. 43.2, translated in an object-oriented system. 

The sum on the right side of (9.14) corresponds to g(E,k) in a single crystal. The PDOS g(E) for randomly oriented systems requires an averaging over all crystallographic directions. 

B9. Boyer, H. M., A User Oriented System Design Program, presented at the Pacific Coast Gas Assoc. Distribution Conf., Los Angeles, California, 1970. 

For oriented systems, the determination of molecular conformation is a complex problem because Raman spectra contain signals inherently due to both molecular conformation and orientation. To extract only the information relative to the conformation, one has to calculate a spectrum that is independent of orientation, in a similar way to the A0 structural absorbance of IR spectroscopy (Section 4). Frisk et al. [57] have shown that for a uniaxial sample aligned along the Z-axis, a spectrum independent of orientation (so-called isotropic spectrum), fso, can be calculated from the following linear combination of four polarized spectra [57]... 

Finally, as in macro-Raman experiments, orientation-insensitive spectra can also be calculated for spectromicroscopy. A method has been developed recently for uniaxially oriented systems and successfully tested on high-density PE rods stretched to a draw ratio of 13 and on Bombyx mori cocoon silk fibers [65]. This method has been theoretically expanded to biaxial samples using the K2 Raman invariant and has proved to be useful to determine the molecular conformation in various polymer thin films [58]. 

NMR spectroscopy is a powerful technique to study molecular structure, order, and dynamics. Because of the anisotropy of the interactions of nuclear spins with each other and with their environment via dipolar, chemical shift, and quadrupolar interactions, the NMR frequencies depend on the orientation of a given molecular unit relative to the external magnetic field. NMR spectroscopy is thus quite valuable to characterize partially oriented systems. Solid-state NMR... 

Raman microscopy provides a spatial resolution slightly better than IR, and no sample preparation is necessary in many cases. It has advantages with special types of substances (e.g., systems containing conjugated double bonds, oriented systems, amorphous and crystalline carbon, oxides). SNOM techniques (with spatial resolution below 1 pm) have been more popular with Raman than with IR, so far, but as yet are not routinely practiced. 

A few examples of the moduli of systems with simple symmetry will be discussed. Figure 1A illustrates one type of anisotropic system, known as uniaxial orthotropic. The lines in the figure could represent oriented segments of polymer chains, or they could be fibers in a composite material. This uniaxially oriented system has five independent elastic moduli if the lines (or fibers) ara randomly spaced when viewed from the end. Uniaxial systems have six moduli if the ends of the fibers arc packed in a pattern such as cubic or hexagonal packing. The five engineering moduli are il-... 

The purpose of this chapter is to provide a review of research conducted in the senior author s laboratory over the past 15 years on the stereochemistry of intra- and inter-molecular interactions in a special kind of highly oriented system—monolayers. 

Embley91] Embley, D., et al. 1991. Object-Oriented Systems Analysis A Model-Driven Approach. Englewood Cliffs, N.J. Prentice Hall. 

Helm90] Helm, Richard, I. M. Holland, andD. Gangopadhyay. 1990. Contracts Specifying behavioral compositions in object-oriented systems. In Proceedings of OOPSLA/... 

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