Code Case nomenclature

The three-letter abbreviations for each of the amino acids are listed in Table 27.1. In most cases, these codes take the first three letters of the name of the amino acid however, isoleucine is abbreviated ile, glutamine is abbreviated gin, and tryptophan is abbreviated trp. A one-letter code is used for particrdarly large peptides, and those codes are also listed in Table 27.1. Using the three-letter codes from Table 27.1, 124 is ala-val-ser-leu-ala-phe-glu-met-his it is A-V-S-L-A-F-E-M-H, using the one-letter codes. This nomenclature system makes it easier to write the structure of a peptide, but it demands memorization of the code to go with each amino acid. 

While the trivial and trade nomenclature in most cases has accidental character, the lUPAC Commission has worked out a series of rules [4] which allow the great majority of structures to be represented uniformly, though there still exists some ambiguity within this nomenclature. Thus, many structures can have more than one name. It is important that the rules of some dialects of the lUPAC systematic nomenclature are transformed into a program code. Thus, programs for generating the names from chemical structures, and vice versa (structures from names) have been created [5] (see Chapter II, Section 2 in the Handbook). 

Although the protocol with respect to parentheses established in Section 1 would seem to allow (19) to be written as H1C1C11 11C1C1H, and, similarly, for (20), a different interpretation is given to this code. Namely, the parentheses, in such cases, are regarded as an integral part of the cylindrical name, rather than an abbreviating factor, and thus the above expansion is not a valid one. This aspect of the nomenclature will be clarified in Chapter 6. 

This nomenclature is however not always adhered to. In many cases, i.e. scientific publications, codes of practice, or official directives, an analytical procedure is virtually implied when an analytical method is spoken about. Commonly used expressions such as validation of analytical methods or performance characteristics of analytical methods are typical examples of incorrect usage. Such confusion appears even in the definition suggested by Wilson in 1970 for the term analytical method [9]. As he then put it, an analytical method is to be regarded as the set of written instructions completely defining the procedure to be adopted by the analyst in order to obtain the required analytical result . It is actually difficult to make a distinction between the two notions when one of them is defined in terms of the other. 

Articles 2—4 indicate the various ranks employed in nomenclature, the sequence of which may not be altered. If a tribe is described under a genus, this tribal name is invalid (Art. 33.4, but see the special case for Fungi in 33.5). Sometimes special ranks have been introduced to make the units distinguished in the group concerned mere clear, e.g. entities in Drimys. Such ranks and names have no status under the Code, it is recommended here to act as if the pertinent rules apply, but they have certainly no priority, nor influence the application of names in official ranks. 

It is not always easy to decide that two names are really identical as is shown by the Examples given here. The Code is not very clear on this point. When in doubt it is best to look for similar cases, to ask your colleagues, and if still not satisfied to write a letter to the Nomenclatural Committee for expert advise. In general existing usage should be maintained. 

To make it easy we suggest here to follow the lower-case three-letter code nomenclature for nets proposed by O Keeffe and coworkers [22, 23] in an attempt to overcome a certain confusion in the field, due to the fact that some networks... 

Before we discuss the monomers that are used in PPAs, it is in order to talk briefly about the nomenclature of these types of polymers. In nylons, there is common nomenclature to identify the types by a number code. The numbers refer to the chain lengths of the diamine and the diacid. In the case of aromatic compounds, for IPA, I is used and for TPA, T is used. In PPA, a similar nomenclature is used. Examples are given in Table 12.1. However, for fully aromatic PAs the nomenclature is not extended for practical use. 

Section 1. The first part of Section 1 identifies the substance by name, formula, and various numbers and codes. Most organic compounds have more than one name. In this case, the systematic (or International Union of Pure and Applied Chemistry [lUPAC]) name is methanol, and the other names are common names or are from an older system of nomenclature. The Chemical Abstract Service Number (CAS No.) is often used to identify a substance, and it may be used to access extensive information about a substance found in many computer databases or in the library. 

Several methods for structure representation have been developed. Each representation derives from the two-dimensional structural diagram and is sufficient to provide a simple characterization of that structure. This characterization is ambiguous if it represents more than a single structure, as in the case of fragmentation codes, or unambiguous if it represents a single structure only, as in the case of nomenclature, linear notation, and connection table representations. 

By the late 1950s, enzyme nomenclature was in confusion. Without any guiding authority, the increase in known enzymes had led to the assignment of misleading or inappropriate names, and in many cases the same enzyme became known by several names while some catalytically different enzymes were identically named. In 1961, the first Enzyme Commission reported a system for enzyme classification and the assignment of code numbers. 

In EU, as mentioned in Section 1.2, the substances allowed to be used as colouring agents in cosmetics are listed in Annex IV of the EU Cosmetics Directive (Council Directive 76/768/EEC). Except for a few cases, they are usually listed by their Colour Index (Cl) numbers, which is a code number assigned by the Society of Dyers and Colourists (SDC) in conjunction with the American Association of Textile Chemists and Colorists (AATCC). For example, the colouring agent tartrazine is named as Cl 19140. This nomenclature is... 

---