Articles definition

There are three types of entries in this Encyclopedia regular articles, definition entries, and descriptions of software packages along with a brief feature on the respective vendor. All articles essentially have the same general structure abbreviations, glossary of terms, main text, related articles, and... 

This technique is used to quantify one or more components in a mixture, i.e., extracting them from mixtures to facilitate their final analysis. An example is that for the asphaltenes, already described in the definition of these components in article 1,2.1. 

The appropriate quantum mechanical operator fomi of the phase has been the subject of numerous efforts. At present, one can only speak of the best approximate operator, and this also is the subject of debate. A personal historical account by Nieto of various operator definitions for the phase (and of its probability distribution) is in [27] and in companion articles, for example, [130-132] and others, that have appeared in Volume 48 of Physica Scripta T (1993), which is devoted to this subject. (For an introduction to the unitarity requirements placed on a phase operator, one can refer to [133]). In 1927, Dirac proposed a quantum mechanical operator tf), defined in terms of the creation and destruction operators [134], but London [135] showed that this is not Hermitean. (A further source is [136].) Another candidate, e is not unitary. 

The term feedstock in this article refers not only to coal, but also to products and coproducts of coal conversion processes used to meet the raw material needs of the chemical industry. This definition distinguishes between use of coal-derived products for fuels and for chemicals, but this distinction is somewhat arbitrary because the products involved in fuel and chemical appHcations are often identical or related by simple transformations. For example, methanol has been widely promoted and used as a component of motor fuel, but it is also used heavily in the chemical industry. Frequendy, some or all of the chemical products of a coal conversion process are not isolated but used as process fuel. This practice is common in the many coke plants that are now burning coal tar and naphtha in the ovens. 

The Textile Eiber Product Identification Act (TEPIA) requires that the fiber content of textile articles be labeled (16). The Eederal Trade Commission estabhshed and periodically refines the generic fiber definitions. The current definition for a polyester fiber is "A manufactured fiber ia which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxyUc acid, including but not restricted to terephthalate units, and para substituted hydroxyben2oate units."... 

Metrologia International Committee of Weights and Measures (CIPM) Pavilion de Breteuil Parc de St. Cloud, Prance Includes articles on scientific metrology worldwide, improvements in measuring techniques and standards, definitions of units, and the activities of various bodies created by the International Metric Convention. 

Coining The sintered compact is pressed to obtain a definite surface configuration which changes the shape of the article. In some instances, the sintered piece is used as a blank with most of the surface configuration produced by coining such as in striking coins or medaUions. 

This article is an iatroduction and survey that states the fundamental principles and definitions of catalysis, demonstrates the unity of the subject, and places it ia an appHed perspective. The selection of iadustrial catalytic processes discussed has been made for the sake of ikustrating principles and representative characteristics of catalysis and catalytic processes. Details of the processes are given ia numerous other articles ia the Eniyclopedia. 

Certain commercial materials and equipment may be identified in the article for adequate definition of subject matter. In no instance does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, or that the material or equipment is necessarily the best available for the purpose. 

The traditional view of emulsion stability (1,2) was concerned with systems of two isotropic, Newtonian Hquids of which one is dispersed in the other in the form of spherical droplets. The stabilization of such a system was achieved by adsorbed amphiphiles, which modify interfacial properties and to some extent the colloidal forces across a thin Hquid film, after the hydrodynamic conditions of the latter had been taken into consideration. However, a large number of emulsions, in fact, contain more than two phases. The importance of the third phase was recognized early (3) and the lUPAC definition of an emulsion included a third phase (4). With this relation in mind, this article deals with two-phase emulsions as an introduction. These systems are useful in discussing the details of formation and destabilization, because of their relative simplicity. The subsequent treatment focuses on three-phase emulsions, outlining three special cases. The presence of the third phase is shown in order to monitor the properties of the emulsion in a significant manner. 

Definitions Following the practice presented under Gas-Separation Membranes, distillation notation is used. Literature articles often use mass fraction instead of mole fraction, but the substitution of one to the other is easily made. 

Family of the scientist has presented documentar y materials to Academy of sciences in June 1974. Among them, the most important ar e manuscripts, typewritten copies about 100 scientific works of the scientist and working materials to them. Its includes articles, reports, monographs, the textbooks written by A.K. Babko during last 25 year s working writing-books with extracts, marks on various questions, abstracts of chemical literature responses and reviews on thesis of Ph.D. and doctor s degrees, on ar ticles, books, textbooks. For example, early works Product of solubility , To a technique of definition of strontium in minerals (1940-s), many unpublished works in 1940-1960, etc. 

Two other terms need definition transverse pitch a and longitudinal pitch b. For a drawing of these dimensions see the source article. For our purposes appropriate lengths are shown in Table 3. 

Kerridge has provided an excellent article on the interface betw een the operating company and the contractor to define all requirements in complete and standardized detail. This includes who is responsible for every deliverable. The operating company and contractor must work as a team. An example of one area that needs to be reviewed often with the contractor is the provision of secondary systems as packages, perhaps from a third party. Such systems can easily become orphans. This problem is discussed in the Process Definition section of Chapter 16. 

Para, Tube or Bamboo Curare. This variety was packed in sections of bamboo, but this almost traditional information needs modification since tube curare became a commercial article. It is now a viscous, solid or even powdered extract, exported in sealed tins. In view of the relationship established between bebeerine, curine, and tubocurarhie, the active alkaloid of this variety of curare, the suggestion was made, first by Spath, Leithe and Ladeck, and more definitely by King that its botanical source should be sought among the Brazilian Menispermaceae, and as shown later the search for the source of the d-tubocurarine found in this variety of curare has been narrowed down to Chondrodendron tomentosum, or possibly a closely related species liable to be confused with it. 

The product of force F and the rolling radius (R) of the tires on the drive wheels is the wheel torque (T). Power depends on both torque and rotational speed (N). By definition, power is given by P = 2tiNFR = 27tNT. Wlien driving at constant speed, the driver adjusts the accelerator pedal so the drive-wheel power exactly matches the power required (P,) to overcome the resistance of the vehicle (discussed later in this article). To accelerate the vehicle, the driver further depresses the accelerator pedal so that the power available at the drit c wheels (PJ exceeds P,.. 

Refs to nitrated materials, eg Cellulose Nitrate, Cyclonite etc., already described in this Encyclopedia will be found in Sections 11 111 In view of the definition of nitration presented above and the concepts to be developed in Section VIII, discussion of nitrate salts such as H2NNH2.HNG3 or CH3NH2.HN03 etc is not included in this article... 

The term particle and particle size are so highly ambiguous as to require precise definition. As used in this article particles will.be limited by size to those distinct entities which have physically detectable boundaries in any direction within the limits of 0.05 and 10 microns (1 micron, p -0.001mm). This size range covers those particles which can be directly measured without magnification down to those which exhibit colloidal behavior... 

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). 

Manley-Harris and Richards (Missoula, Montana) have compiled a comprehensive account of the dianhydrides of D-fructose and related compounds, more than 30 in all. These compounds, several of which are of importance in the sugar industry, have in the past presented significant problems in their chemical characterization. Their chemistry was surveyed as early as 1945 by McDonald in Volume 2 of this series, and discussed again in Volume 22 by Verstraeten. The current article furnishes detailed NMR data for each of the anhydrides, providing definitive reference data for accurate identification and correlation with earlier literature, where erroneous structural attributions are rather frequent. 

Unfortunately, relatively little work has been done on the solution thermodynamics of concentrated polymer solutions with "gathering". The definitive work on the subject Is the article of Yamamoto and White (17). The corresponding-states theory of Flory (11) does not account for gathering. We therefore restrict our consideration here to multicomponent solutions where the solvents and polymer are nonpolar. For such solutions, gathering Is unlikely to occur. 

Twenty years ago, Walter Riidorff wrote a review for this series entitled "Graphite Intercalation Compounds Oil). It was one of four definitive articles to come out in 1959 and 1960 (HI, Cl, Ul), a period of intense activity in graphite research. We have now again reached the "fever pitch, with not only the appearance of several new articles El, H2, Wl) but also the convening of the first international conference dedicated exclusively to graphite compounds (H3). In the following, we shall concentrate on work performed between 1974 and the present. 

---