Undesired structures

Very undesirable structural irregularities are 0-0 bonds that may be introduced into the polymer during its storage and/or during the polymerization of monomers not sufficiently deprived from oxygen. 

The primary method for demonstration of the existence of drug polymorphs, or solvate species, is that of powder x-ray diffraction (XRD). Such measurements represent a specification of the internal structure within a crystal, and an evaluation of its lattice type. Since dissolution and subsequent drying can sometimes yield an undesired structure, it is also important to confirm crystal structures at each formulation stage during the beginning of the development process. 

The application of computational algorithms for compound filtering and clustering is routinely used to eliminate undesired structures on the basis of chemically reactive fimctionalities, predicted liabilities (e.g., frequent hitters, hERG, cyp450 and so forth), or druglike properties. Computational methods are also used to group compoimds on... 

Further basic postulates deal with structures, those relatively permanent structures/functions/subsystems of the mind/brain that act on information to transform it in various ways. Arithmetical skills, for example, constitute a (set of related) structure(s). The structures of particular interest to us are those that require some amount of attention/awareness to activate them. Attention/awareness acts as psychological energy in this sense. Most techniques for controlling the mind are ways of deploying attention/awareness energy and other kinds of energies so as to activate desired structures (traits, skills, attitudes) and deactivate undesired structures. 

As described in Section 2, the coercivity of hard magnetic materials is generally determined by undesired structural defects. As the size of hard particles is progressively reduced, the coercive field tends to increase. This is explained by considering that the impact of a given defect extends to the volume of the concerned particle. It is reduced as the particle size is reduced. However, below a certain critical size, a reduction in coercivity is observed. The process used to reduce particle size inevitably introduces additional defects, which become dominant. 

All remainingligands are docked into the target protein and a list of some hundred to several thousand small molecules, each with a computed score, is produced. These have to be further analyzed to discard undesirable structures. Selection criteria could be any of the following ... 

The results from the preliminary or lead optimization studies conducted by these disciplines are integrated with the biological activity data from the pharmacologist. If stability, delivery, metabolism, or toxicity problems are encountered, the chemists use the previously generated SAR information to modify the structure of the lead without destroying the site(s) required for biological activity of the compound. The new compounds are evaluated for potency and to ensure that the undesirable structural attribute, which causes the developability problem, has been deleted or minimized. Then... 

There are two drawbacks in employing the chiral pool approach. First, a natural product usually exists as a single enantiomer, and therefore only a single enantiomer of a pheromone can be prepared easily. Secondly, a natural product possesses a definite structure, which is often quite different from that of a pheromone. Accordingly, the synthesis may become lengthy to remove the undesired structural features in the starting natural product. 

Each reaction yields a set of products which are indexed by pointers to their precursors These pointers are maintained at each step in the expansion of the tree so that information (constraints) applied to products at any level automatically results in appropriate action (pruning away undesired structures) at all levels below and above the given level ... 

One of the most critical limitations of a DNA-encoded library is DNA itself It requires an aqueous media and mild environmental conditions to ensure DNA s chemical stability and hybridization fidelity. Naturally, many useful chemical reactions cannot be directly applied. Liu and co-workers have adapted a variety of organic reactions into DNA-compatible format however, a survey of the structures synthesized by DNA encoding indicates the compounds made by DNA-templated chemistry are still being confined within the paradigm of pep-tidic structures, an undesired structural feature for drug molecules. 

Etching pits and other undesirable structures may develop on the grain faces. 

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