Duplicate atom

If the first-encountered ring atom of the ligand is the quaternary common atom of a bicyclic system, one of the three ring bonds is kept intact and the other two are broken. Three branches of the tree graph, which are provided at their ends with requisite duplicate atoms, are therefore produced (Example 2, Table 4). 

If X or Y is a trigonal center in a double bond, then the selection of the preferred substituent requires application of the standard duplicate atom procedure. Of course, the magnitude of the torsional angle is defined by the original atom (examples 5, 6). 

If an atom is attached to another hy a multiple bond (double or triple) both atoms are considered to be duplicated. The duplicated atom (X°) is considered to have a valence of zero and has a lower priority than a real atom (X), if that is the only point of difference. 

Generally, both X° and X are simply treated as real atoms. If the only choice is between a duplicated atom X° and a real atom (X), however, the duplicated atom has a lower priority (in this case, all other rules have failed to establish the priorities). With the ferf-butyl fragment, for example, proceeding down the chain to the first point of difference leads to ferf-butyl with a lower priority than the alkynyl fragment ... 

A common observation for multiple conformations is that bonds and angles can be distorted for the atoms that are at the border between the ordered and the disordered part. A single solution is to duplicate atoms from the ordered part such that strain can be released by small movement of the atoms in the different conformers. This strategy is, of course, at the expense of additional parameters. A typical example are CA-atoms of residues with disordered side chains in many cases the positions of the CB atom will be slightly different between the different conformers, which, naturally, entails different positions of the CA and the other backbone atoms of the respective backbone atoms as well. Including more and more atoms into the disordered parts will successively resolve stereochemical problems but can lead to a zippering up of large part of the stmcture which is not always desirable—some compromise has to be accepted in such cases. 

Since the periodic im iipes are exact copies oT Lh e original box, movements of atoms in the original box are duplicated in the images. When a particle leaves a box. its periodic image enters I rom the opposite box side and replaces it. This con serves the n limber or atom s in each box. 

Mean values from duplicate analyses of each of three samples by atomic absorption spectrophotometry. 

You can t duplicate these molecular weights for C7H16 and CsHa02 by using the atomic weights given in the periodic table. Those values are for the natural-abundance mixture of isotopes. The exact values are 12.00000 for C, 1.00783 for H, and 15.9949 for 0. 

In a segmented contraction each primitive as a rule is only used in one contracted function. In some cases it may be necessary to duplicate one or two PGTOs in two adjacent CGTOs. The contraction coefficients can be determined by a variational optimization, for example from an atomic HF calculation. 

It must be pointed out that the atomic absorption system as used today, cannot accurately determine the calcium level of a solution. The reason for this is that results will vary depending upon the other elements present and the composition of the solution. Since it is impossible to duplicate every feature of the particular serum being analyzed, results have to be compared to standards which have been made up in serum dialysates. Such standards are available in the form of the Versatols where the calcium has been dialyzed out and then weighed back. This is distinct from substances such as Validate, which are used as controls and which values are re-sults of analysis. The variability of serum composition has significantly widened what is now considered the "normal range" for serum Ca assay when done by atomic absorption (37a). 

Groups containing double or triple bonds are assigned priority as if both atoms were duplicated or triplicated. 

Klinkhammer [432] has described a method for determining manganese in a seawater matrix at concentrations ranging from about 30 to 5500 ng/1. The samples are extracted with 4 nmol/1 8-hydroxyquinoline in chloroform, and the manganese in the organic phase is then back-extracted into 3 M nitric acid. The manganese concentrations are determined by graphite furnace atomic absorption spectrophotometry. The blank of the method is about 3.0 ng/1, and the precision from duplicate analyses is 9% (1 SD). 

The atoms attached to the multiple bound are considered to be duplicated (for a double... 

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