Unwanted Structural Elements

A key factor to the success was that the substrate possessed crucial structural elements in common with the natural substrates of the enzyme, bulky side-chain amino acids. Since cheap commercial sources for the enzyme were available on the market the enzyme could be discarded. Also adding to the process was the fact that the unwanted retained enantiomer could be racemized and recycled by a simple procedure. 

During sample preparation and electrophoresis DNA will not be denaturated, i.e., the double strand and higher elements of structure stay unaffected. To avoid unwanted further fragmentation all manipulations have to be done without possible contaminations by fingerprints, droplets of saliva or microorganisms. Sterilized materials are recommended. 

The necessity to have more than one component in a catalyst arises from many needs those linked to the polyfunctionality often required for the different steps in a reaction, the need to enhance the rate of some reaction steps, inhibition of unwanted side reactions, provision of adequate thermal stability, to take advantage of observed synergetic effects. From a fundamental point of view, the presence of several metal elements in a common structure permits the adjustment of the local electronic properties, imposes well defined coordinations, limits the extent of oxidation-reduction phenomena, and may stabilize the whole catalyst by retarding sintering. Mixed oxide catalysts are used as such, or as precursors of active catalysts, for a whole range of important industrial processes, a representative selection of which is given in Table 1. 

So far the emphasis has been on solving the crystal structure from the knowledge of the unit cell and ionic content. The motivation for this work is to provide an automated procedure to help determine or solve the crystal structure of new compounds that are synthesised in a powder form. Of course the methods developed can generate other structural topologies and perhaps a new, yet to be synthesised, crystal structure. However, the task has been to solve a particular structure and so one might extract more information from the experimental data to aid the prediction process (e.g. use of symmetry elements). Thus, the number of unwanted possible (meta)stable structures, or polymorphs, that could be generated may be reduced. In this section, the emphasis is on finding all the important polymorphs for a particular chemical formula. 

A text file containing the notlist for reagent searching Enter line notations for unwanted fragments, e.g., to remove bifunctional acids (line 1 of the file) as well as a list of atom types (elements) (line 2) you do not want to see in the reagent structures (see Note 11) ... 

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