Catalogs

W.C. Chew. Waves and fields in inhomogeneous media. Library of Congress Cataloging-in-Publication Data, ISBN 0-442-23816-9, 1990. 

I. Langmuir, Colloid Symposium Monograph, The Chemical Catalog Company, New York, 1925, p. 48. 

Ippen E 1997 Characterizing optical components for ultrafast laser applications Optics 1997/98 Catalog (Irvine, CA Newport Corp.) pp 8-2-8-3... 

Hash codes of molecules which are already pre-computed are suitable for use in fiill structure searches in database applications. The compression of the code of a chemical structure into only one number also makes it possible to compute in advance the transformation results for a whole catalog. The files can be stored and kept complete in the core memory during execution of the program, so that a search can be accomplished within seconds. 

Factual databases mainly contain alphanumeric data on chemical compounds. In contrast to bibliographic databases, factual databases directly describe the objects primary data on chemical compounds) and provide the required information on them. Factual databases can be divided into numeric databases, metadatabases, research project databases, and catalogs of chemical compounds. 

Factual databases may provide the electronic version of printed catalogs on chemical compoimds. The catalogs of different suppliers of chemicals serve to identify chemical compounds with their appropriate synonyms, molecular formulas, molecular weight, structure diagrams, and - of course - the price. Sometimes the data are linked to other databases that contain additional information. Structure and substructure search possibihties have now been included in most of the databases of chemical suppliers. 

Cl Il MCATS Cl ll-VfCAI S is a catalog file containing information on aboul 6 million com-merciallyavailable chemicals and iheir worldwide suppliers (702) (March, 2003),... 

Many biochemical databases with sophisticated topics have been developed for solving various problems. Since 1996 the first issue of each journal volume of Nucleic Acid Research has been reserved for the presentation of molecular biology databases [28]. A comprehensive catalog on the Internet is DBCAT, currently listing 511 databases [29, 30). 

To seat ch for available starting materials, similarity searches, substructure searches, and some classical retrieval methods such as full structure searches, name searches, empirical formula searches, etc., have been integrated into the system. All searches can be applied to a number of catalogs of available fine chemicals (c.g, Fluka 154]. In addition, compound libraries such as in-housc catalogs can easily be integrated. 

Figure 10.3-16. The principle of similarity searches. The query (target, precursor) as well as the catalog compound are transformed by the criterion maximum oxidation state". Since the transformation for both compounds results in the samie transformed structure, the catalog compound is presented to the user as a suitable starting material. The comparison of the structure is performed by a hashcode algorithm.

Figure 10.3-39. A substructure search in a catalog of fine chemicals. The precursor illustrated may be needed for the synthesis of a library, A substructure is defi ned by setting an open site at the position of the R group. Some representative examples of the 69 compounds in the Acros catalog which were obtained are shown.

Next wc turned our attention to the question of whether wc could still sec the separation of the two sets of molecules when they were buried in a large data set of diverse structures. For this purpose we added this data set of 172 molecules to the entire catalog of 8223 compounds available from a chemical supplier (janssen Chimica). Now, having a larger data set one also has to increase the size of the network a network of 40 X 30 neurons was chosen. Training this network with the same 49-dimcnsional structure representation as previously described, but now for all 8395 structures, provided the map shown in Figure 10,4-9. 

Figure 10.4-9. Kohonen map (40 / 30) of a data set consisting of the dopamine and benzodiazepine agonists of Figure 10.4-8 and 8323 compounds in a chemical supplier s catalog.

One final thought. Strike found that there are a lot of companies that do not sell sodium bisulfite (NaHSOa). In fact, a lot of companies list sodium bisulfite in their catalogs but tell the reader to see sodium metabisulfite instead because that is the only form of this compound they carry. In other words, a lot of companies sell sodium metabisulfite (NaaSaOs) as an acceptable alternative to the other. The Merck Index even says about sodium bisulfite that the [sodium] bisulfite of commerce consists chiefly of sodium metabisulfite, Nd2S20s, and for all practical purposes possesses the same properties as the true bisulfite". What this meant to Strike was that metabisulfite would work just as well. So some was purchased and tried. And it really does work just the samel... 

Table 7.76 is condensed, with permission, from the Catalog of Mass Spectral Data of the American Petroleum Institute Research Project 44. These, and other tables, should be consulted for further and more detailed information. 

Analysis sheet for Simulated Rainwater (SRM 2694a). Adapted from NIST Special Publication 250 Standard Reference Materials Catalog 1995-96, p. 54 U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology. 

---