Compositional nomenclature

Another form of official publication that interests but does not directly concern chemists is standards. Standards which are of great industrial importance can refer to nomenclature, composition, dimensions, quality or testing of a product or process. Their value is that they simplify production and distribution, ensure uniformity, eliminate wasteful variety and confer a kind of status on those which conform. 

In the following sections, we will first outline the types of peptides present in lipoproteins and then briefly describe the broad classes of lipoproteins, summarizing their nomenclature, composition, functions and biosynthesis. This will be followed by a more detailed description of the metabolic interrelationships between lipoproteins and how their metabolism is integrated within the body. Methods of isolation and analysis will be described and the section will end with a summary of their clinical relevance, leading to a discussion of the importance of lipoprotein metabolism in some metabolic diseases. 

Most of the octane blending values reported ia the Hterature use a slight variation on this theoretically sound approach. The composition and octane of the base fuel are assumed to be fixed and the second component is assumed to be added. Using the same nomenclature, the blending octane number (BON) of component 2 is defined as... 

In the days of alchemy and the phlogiston theory, no system of nomenclature that would be considered logical ia the 1990s was possible. Names were not based on composition, but on historical association, eg, Glauber s salt for sodium sulfate decahydrate and Epsom salt for magnesium sulfate physical characteristics, eg, spirit of wiae for ethanol, oil of vitriol for sulfuric acid, butter of antimony for antimony trichloride, Hver of sulfur for potassium sulfide, and cream of tartar for potassium hydrogen tartrate or physiological behavior, eg, caustic soda for sodium hydroxide. Some of these common or trivial names persist, especially ia the nonchemical Hterature. Such names were a necessity at the time they were iatroduced because the concept of molecular stmcture had not been developed, and even elemental composition was incomplete or iadeterminate for many substances. 

Elemental composition, ionic charge, and oxidation state are the dominant considerations in inorganic nomenclature. Coimectivity, ie, which atoms are linked by bonds to which other atoms, has not generally been considered to be important, and indeed, in some types of compounds, such as cluster compounds, it caimot be appHed unambiguously. However, when it is necessary to indicate coimectivity, itaUcized symbols for the connected atoms are used, as in trioxodinitrate(A/,A/), O2N—NO . The nomenclature that has been presented appHes to isolated molecules (or ions). Eor substances in the soHd state, which may have more than one crystal stmcture, with individual connectivities, two devices are used. The name of a mineral that exemplifies a particular crystal stmcture, eg, mtile or perovskite, may be appended. Alternatively, the crystal stmcture symmetry, eg, rhombic or triclinic, may be cited, or the stmcture may be stated in a phrase, eg, face-centered cubic. 

Figure 4 shows the general arrangement and nomenclature for a humidification or dehumidification process, where the subscript 1 refers to the bottom of the column, and subscript 2 to the top. Steady state is assumed. Flow rates and compositions are given in molar terms because this simplifies the results. 

Vimses contain either RNA or DNA, and this nucleic acid composition forms the basis for thek classification. Although vimses ate known to infect bactetia, insects, plants, animals, and humans, this discussion is restticted to the important vimses of vertebrates. The relevant vimses ate summarized in Table 2, using the nomenclature and taxonomy recommended by the International Committee on Taxonomy of Vimses (4,5). 

Nomenclature. Colloidal systems necessarily consist of at least two phases, the coUoid and the continuous medium or environment in which it resides, and their properties gready depend on the composition and stmcture of each phase. Therefore, it is useful to classify coUoids according to their states of subdivision and agglomeration, and with respect to the dispersing medium. The possible classifications of colloidal systems are given in Table 2. The variety of systems represented in this table underscores the idea that the problems associated with coUoids are usuaUy interdisciplinary in nature and that a broad scientific base is required to understand them completely. 

To determine the reasonableness of the top and bottom compositions of a fractionation column, a Hengstebeck plot is fast and easy (Reference 4). First, select a heavy key component and determine the relative volatility (a) of all column components to the heavy key. The a can be otfeed or perhaps more accurately cc = (a,op oCboitom) - Plot In D/B versus In a and the component points should fall close to a straight line. If a fairly straight line does not result, the compositions are suspect. A nomenclature table is provided at the end of this chapter. 

Actually, because of the stress and deformation hypotheses that are an inseparable part of classical lamination theory, a more correct name would be classical thin lamination theory, or even classical laminated plate theory. We wiiruS ffi bmmon term classical lamination theory, but recognize that it is a convenient oversimplification of the rigorous nomenclature. In the composite materials literature, classical laminationtheoryls en abbreviated as CLT. 

Many compounds were given informal, common names before their compositions were known. Common names include water, salt, sugar, ammonia, and quartz. A systematic name, on the other hand, reveals which dements are present and, in some cases, the arrangement of atoms. The systemic naming of compounds, which is called chemical nomenclature, follows the simple rules described in this section. 

Over the past two decades, the pharmaceutical community has become acutely aware that many substances of interest can be obtained in more than one crystal form, and that the properties of these solids may often be quite different. Polymorphism is the term used to denote crystal systems where a substance can exist in different crystal packing arrangements, but all of which are characterized by exactly the same elemental composition. Other crystal variations are known where a given substance exists in different crystal packing arrangements, but each of which exhibits a different elemental composition. Since this latter phenomenon usually involves the inclusion of one or more solvent molecules in the crystal, the term solvatomorphism has been coined to replace the inconsistent nomenclature used over the years. These and related phenomena have been the focus of several recent monographs [1-3],... 

In 1965 Seshardri et al. described the isolation of an unknown terpenoid acid B obtained from the lichens of Lobaria retigera in the western Himalayas [8]. (Note that this annotation bears no relation to the subsequent nomenclature later defined by Corey and Shibata.) Four collections had been made in the summer of 1962 from under the Rutba plants in the Valley of Flowers (12,500 feet) and on the way to Hemkund Lokpal (13,500 feet) and from underneath rocks and from pine trees in Ganghariya (10,000 feet). The samples were subjected to a series of increasingly polar extractions (petroleum ether, diethyl ether, acetone). The unknown terpenoid acid B was present in all petroleum ether extracts, except that of the sample obtained from the Valley of Flowers, in compositions ranging from 0.47 % to... 

The effect of solvent composition on the solubility of polymorphs is illustrated by cimetidine [128], The onset of melting of the two forms is essentially indistinguishable, making it impossible to apply the conventional nomenclature to the labeling of the polymorphs. Form B was found to be less soluble than form A, identifying it as the more stable polymorph at room... 

Thus far, we have discussed the nomenclature of different types of chiral systems as well as techniques for determining enantiomer composition. Currently,... 

This chapter has provided a general introduction to stereochemistry, the nomenclature for chiral systems, the determination of enantiomer composition and the determination of absolute configuration. As the focus of this volume is asymmetric synthesis, the coming chapters provide details of the asymmetric syntheses of different chiral molecules. 

Commercial alloys composition, nomenclature. A simple and general way of identification of a commercial alloy (or of a group of similar alloys) consists of a label which gives (as rounded values) the mass% contents of the main components indicated by their chemical symbols. The alloy, for instance, Ti-6A1-4V, is a titanium-based alloy typically containing 6 mass% aluminium and 4 mass% vanadium. 

C, N, and S correspond to heavy over light masses, leading to a consistent nomenclature where a positive bEx value refers to a sample that is relatively enriched in the heavy isotope (a high Ri i ratio relative to the standard). Although some groups have reported isotopic compositions in parts per 10,000 using the e unit (e.g., Rehkamper and Halliday 1999 Zhu et al. 2000), this nomenclature is not very common and should probably be discontinued to avoid confusion. 

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