Registries

It is noted in Sections XVII-10 and 11 that phase transformations may occur, especially in the case of simple gases on uniform surfaces. Such transformations show up in q plots, as illustrated in Fig. XVU-22 for Kr adsorbed on a graphitized carbon black. The two plots are obtained from data just below and just above the limit of stability of a solid phase that is in registry with the graphite lattice [131]. 

Fig. XVII-22. Isosteric heats of adsorption for Kr on graphitized carbon black. Solid line calculated from isotherms at 110.14, 114.14, and 117.14 K dashed line calculated from isotherms at 122.02, 125.05, and 129.00 K. Point A reflects the transition from a fluid to an in-registry solid phase points B and C relate to the transition from the in-registry to and out-of-registry solid phase. The normal monolayer point is about 124 mol/g. [Reprinted with permission from T. P. Vo and T. Fort, Jr., J. Phys. Chem., 91, 6638 (1987) (Ref. 131). Copyright 1987, American Chemical Society.]...

The atomic structure of a surface is usually not a simple tennination of the bulk structure. A classification exists based on the relation of surface to bulk stnicture. A bulk truncated surface has a structure identical to that of the bulk. A relaxed surface has the synnnetry of the bulk stnicture but different interatomic spacings. With respect to the first and second layers, lateral relaxation refers to shifts in layer registry and vertical relaxation refers to shifts in layer spacings. A reconstructed surface has a synnnetry different from that of the bulk synnnetry. The methods of stnictural analysis will be delineated below. 

The WLN was applied to indexing the Chemical Structure Index (CSI) at the Institute for Scientific Information (ISI) [13] and the Ituiex Chemicus Registry System (ICRS) as well as the Crossbow System of Imperial Chemical Industries (ICl). With the introduction of connection tables in the Chemical Abstracts Service (CAS) in 1965 and the advent of molecular editors in the 1970s, which directly produced connection tables, the WLN lost its importance. 

One of the more prominent integrated databases is provided by CAS - the Registry CAPLUS, CA, CAOLD. All of these diverse databases are based on the... 

In addition to the numeric data (color, solubility, refraction index, spectra, etc.), these factual databases also include a bibliographic section with references or sources and a section with information for the identification of a compound (e.g., name, CAS Registry Number, molecular weight). 

Examples of structure databases are Beilstein, Gmehn, and CAS Registry. 

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

The CA Registry of CAS also comprises 1.6 million protein and peptide sequences and over 21.6 milhon nudeic acid sequences from literature sources and from GenBank. 

The CAS Registry contains information on all the chemical compounds published in the literature since 1957. The sources of these 21 million compounds are 9000 international journals containing chemical information. The database includes CAS Registry Numbers, the CAS name (not conforming to the lUPAC convention) with synonyms, and molecular and structural formulas. The CAS provides a weekly update (see Section 5.4). 

REGISTRY Chemical Abstracts Service (CAS), USA chemical substances struc- ture 22 mio struct., 25 mio sequences 9000 journals, 37 patent offices, proceedings, books STN commerdal CD-ROM, online daily www.cas.OTg... 

Compounds are stored as connection tables (CT) in structure and reaction databases, e.g., Beilstein, Cmelin, CAS Registry, and CASREACT. 

The problem of perception complete structures is related to the problem of their representation, for which the basic requirements are to represent as much as possible the functionality of the structure, to be unique, and to allow the restoration of the structure. Various approaches have been devised to this end. They comprise the use of molecular formulas, molecular weights, trade and/or trivial names, various line notations, registry numbers, constitutional diagrams 2D representations), atom coordinates (2D or 3D representations), topological indices, hash codes, and others (see Chapter 2). 

Add the new type and its mass to the file pointed to by the AtotTi fypcMass cri try of the Registry or the cheni.itii file for the appropriate force field. 

The sexlic bending term is a scale factor ST times the t iiadratic bending term. This constant SPcan be set to an arbitrary value by an entry m the Registry or the chem.ini file. The default value for MM+ is SP= 7.0 X 10 . The constant 0.043828 converts the MM-r... 

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