Pragmatics

A given pair of anchors may be part of several loops, containing different conical intersections. A systematic search for the third anchor is conducted by considering the electrons that are to be re-paired (i.e., that form the chemical bonds that are created in the reaction), A pragmatic and systematic way of doing this is by considering first the re-pairing of the smallest possible number of... 

We employ the general scheme presented above as a starting point in our discussion of various approaches for handling the R-T effect in triatomic molecules. We And it reasonable to classify these approaches into three categories according to the level of sophistication at which various aspects of the problem are handled. We call them (1) minimal models (2) pragmatic models (3) benchmark treatments. The criterions for such a classification are given in Table I. 

IlyperChem has a set of optimi/.ers available to es.plore potential surfaces. These differ in their generality, convergence properties and conipntaiioiial requirements. One must be somewhat pragmatic about optirn i/ation andswitch optirn izers or restart an optimizer when It encounters specific problems. 

Pragmatically, the procedure considers only one atom at a lime, computiiig the 3x3 Hessian matrix associated with that atom and the 3 compon en IS of Ihe gradien t for that atom and then inverts the 3x3 matrix and obtains new coordinates for the atom accord-ingto the Newton-Raphson form u la above. It then goes on lothe next atom and moves it in the same way. using first and second derivatives for the second atom that include any previous nioiioii of atom s. 

Density functional theory (DFT) has become very popular in recent years. This is justified based on the pragmatic observation that it is less computationally intensive than other methods with similar accuracy. This theory has been developed more recently than other ah initio methods. Because of this, there are classes of problems not yet explored with this theory, making it all the more crucial to test the accuracy of the method before applying it to unknown systems. 

In many pyrimidine ring syntheses, it is possible or even desirable to isolate an intermediate ripe for ring-closure by the formation of just one bond. For example, ethyl 3-aminocrotonate (502) reacts with methyl isocyanate to give the ureido ester (503) which may be isolated and subsequently converted into 3,6-dimethyluracil (504) by the completion of one bond. However, viewed pragmatically, the whole synthesis involves the formation of two bonds and therefore is so classified. On such criteria, only two pyrimidine/quinazoline syntheses involve the formation of only one bond. 

Kinds of Catalyzed Organic Reactions A fundamental classification of organic reactions is possible on the basis of the lands of bonds that are formed or destroyed and the natures of eliminations, substitutions, and additions of groups. Here a more pragmatic hst of 20 commercially important lands or classes of reactions will be discussed. In all instances of sohd-catalyzed reactions, chemisorption is a primary step. Often molecules are dissociated on chemisorption into... 

Criteria 2 to 6 are pragmatic criteria which are only applicable to qualitative explanations. These criteria only give qualitative information which is dealt with further below (Section 3.3.3.1). Criterion 7 gives better information with potential test probes (see Section 3.3.3.2). In all the criteria it must be remembered that only mixed potentials can be measured for extended objects to be protected [see the explanation to Eqs. (3-19) and (3-28)]. Criteria 5 and 6 are particularly to be observed for objects [22]. A comparison of the different criteria in field experiments has shown that, besides Criterion 1, good results are obtained with Criterion 3 [26]. 

Pragmatic Protection Criteria for Nonalloyed Ferrous Materials... 

In this section the pragmatic protection criteria of NACE [23] given in Table 3-3 are commented on in light of present knowledge. 

A relation can be derived between and the necessary protection current density from Eq. (5-2) together with the pragmatic protection Criterion 2 in Table 3-3 [seeEq. (3-31)] ... 

Since cathodic protection of concrete structures in the United States has been very much advanced, protection criteria have been developed [46]. They correspond to the pragmatic criteria Nos. 3 and 4 in Table 3-3 (see Section 3.3.3.1). It is assumed that the protective effect is adequate if, upon switching off the protection current, the potential becomes more than 0.1 V more positive within 4 hours. The measurements are carried out in various parts of the protected object with built-in Ag-AgCl reference electrodes or with any electrodes on the external surface. 

Pragmatically, the relative concentrations of elements are determined from the measured ion beam ratios by the application of relative sensitivity factors, which are determined experimentally from standard samples ... 

Starr, C., 1980, Risk Criteria for Nuclear Power Plants A Pragmatic Proposal ANS/ENS International Conference, Washington, DC, November 16-21. 

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