Similar Repeat Internal Units

Certain aspects of permanent gels are comparable if they are analyzed on the basis of the cluster structure of the system. A cluster is a particularly constructed, inhomogeneously linked, multichain macromolecule of a size generally similar to that of most macromolecules studied isolated in dilute solution. As a rule, the cluster is internally very heterogeneous in structure and composition, but, overall, the cluster is the statistically similar repeating unit that builds up the gel. In swelling equilibrium, all parts of a cluster, but its periphery in particular, are in equilibrium with an excess of pure solvent medium. 

Turbidity measurement usually directly relates the forementioned value in a sample to another value in a RM by a controlled comparison of values, or indirectly through an instrument calibration established for values for identical entities in similar RMs. This measurement is characterized, in part, by an observed repeatability and invariably by an estimated uncertainty - the sole indication of the quality for each link. The final link is made to a turbidity unit in an internationally recognized scale. 

More than 10% of all proteins contain sets of two or more domains that are similar to one another. The afore-described sequence search methods can often detect internally repeated sequences that have been characterized in other proteins. Where repeated units do not correspond to previously identified domains, their presence can be detected by attempting to align a given sequence with itself. 

The activity of CALB immobilized on resins 1 to 4 (see Table 1) was assessed by s-CL ring-opening polymerizations. All immobilized resins have similar CALB loading (5.1 to 5.7 %-by-wt) and water content (1.4 to 1.9%). As shown previously , different chemical shifts are observed for methylene protons (-OC//2-) of e-CL monomer, PCL internal repeat units and chain terminal -012-OH moities. Hence, by in situ NMR monitoring, monomer conversion and polymer number average molecular weight (A/ ) were determined. 

In all the two ring-systems discussed above, each elementary repeat unit is constituted of one molecule only, similar to pure discotic materials, and as such differ from true polycatenar materials. Indeed, for the latter, the internal structure of the columns is completely changed upon the elongation of the rigid cores, and the repeat unit is constituted of several molecular species which aggregate together into clusters, these clusters stacking into columns. These systems will be discussed below. 

Let p be the number of atoms in the chemical repeat units and let the indices n and n label the sites of the chemical repeat units along the polymer chain and i and 1 label the 3p internal co-ordinates within the repeat unit. The potential energy can be formally written in a way similar to Eq. (3-13) [50]. 

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