List of structures

First, we must realize that many variables exist in any structural design. We can make a list of structural variables such as sizes, lengths of objects, materials, laminae orientations, and so on. those variables all have influence just as column length, moment of inertia, and Young s modulus influence column-buckling loads. The complete list of design variables will be called the vector Xj, and that vector will have N components. That list constitutes the definition of the structural configuration. 

This by no means exhausts the list of structures proposed for benzene. The remainder, however, such as the structure of Thiele based upon his theory of partial valence and that of Collie based upon a dynamic model, are usually complicated and cannot be represented in any simple valence scheme. 

A list of structurally characterized copper(I) complexes of tripodal aliphatic amines is provided in Table 4 (cf. Section 6.6.3.1.1 for corresponding mononuclear or dinuclear copper(II) complexes). Copper(II) complexes [(L)CuCl]Cl (664) and [(L)Cu(MeCN)][C104]2 (665) with the ligand that is present in complex (662) were also structurally characterized.522... 

There are great similarities between the atomic layer structures formed by Te, Se and S on the low index planes of Au [238]. Table 2 shows a listing of structures... 

Angular information is notably absent from the list of structural parameters normally obtained from XAS. One approach to obtaining angular detail is to make use of multiple scattering effects (17). Unfortunately, this technique is only useful for outer shells (non-nearest neighbor atoms) where there are atoms intervening between the absorber and the scatterer. This technique suffers from complications if the shells of interest overlap in distance with other shells of atoms. 

Some chemicals are susceptible to peroxide formation in the presence of air [10, 56]. Table 2.15 shows a list of structures that can form peroxides. The peroxide formation is normally a slow process. However, highly unstable peroxide products can be formed which can cause an explosion. Some of the chemicals whose structures are shown form explosive peroxides even without a significant concentration (e.g., isopropyl ether, divinyl acetylene, vinylidene chloride, potassium metal, sodium amide). Other substances form a hazardous peroxide on concentration, such as diethyl ether, tetrahydrofuran, and vinyl ethers, or on initiation of a polymerization (e.g., methyl acrylate and styrene) [66]. 

Table 6 List of structurally characterized tin cage compounds and clusters...

Table 7 List of structurally characterized phosphorus cage compounds...

Table 9 List of structurally characterized cage compounds of antimony and bismuth...

The isoprenoids contribute most to the list of structural similarities in the sea and on land. They range from common classes in both ecosystems, such as drimane sesquiterpenes, to rare classes in the sea, such as the trichothecenes (Chart 8.3.11). The similarity in marine and terrestrial polyether triterpenes (Chart 8.3.12) may be seen as convergence toward chemically favored structures, starting from squalene as a biosynthetic precursor. Similar conclusions may apply to polycyclic triterpenes. 

Tellurium forms the most extensive series of homoatomic chalcogen cations. The list of structurally characterised tellurium polycations includes Te4, 6, Te6, Teg and Teg and also the polymeric species (Te4 ) ,... 

Minor variations of the backbone and glycosyl rotations from the fixed values used in the sample computations above produce a variety of theoretically acceptable double helices. As evident from the partial list of structures in Table I, these structures include several 10-fold duplexes similar to the B-DNA models from fiber diffraction studies as well as the larger 13-fgld complex. Despite the large fluctuations in h from 1.7 to 4.3 A, the bases associate at standard separation distances (3 ft < < 4 A and 2.8 X < < 3.0 A) and orientations (A < 30° and < 30°) in all cases. In order to avoid severe steric contacts at small values of h, the bases may tilt up to values of n = 45° with respect to the standard orientation (n = 90°) perpendicular to the helix axis. 

Analysis (PSA) server of BMERC predicts secondary structures and folding classes from a query sequence. On the PSA home page at http //bmerc-www.bu.edu/psa/ index.html, select Submit a sequence analysis request to submit the query sequence and your e-mail address. The returned results include (a) probability distribution plots (conventional X/Y and contour plots) for strand, turn, and helix and (b) a list of structure probabilities for loop, helix, turn, and strand for every amino acid residues. 

Expert systems have been defined as any formal systems , which make predictions about the toxicity of chemicals. All expert systems for the prediction of toxicity are built on experimental data and/or rules derived from such data (Dearden 2003). The expert systems can be further divided into two subclasses based on the method of generating rules. The one method is a knowledge- or rule-based expert system, for which experts/toxicologists create rules based on a list of structural features that have been related to a specified toxicity (Durham and Pearl 2001). An example of a typical knowledge- or rule-based system is DEREK, which will be described later. 

Listing of Structurally Characterized Bis(dithiolene) Complexes (Continued) ... 

Figure 9.3. MACCS— the Molecular ACCess System—an early structure indexing system. This program originally used fixed menus for searching, registration, and reporting. Later versions allowed users to customize the menus. The figure shows the result of a 3D pharmacophore search for ACE inhibitors. Out of a database of 115,000 structures, 21 fit the 2D and 3D requirements of the search query. The user could typically browse the "hits" from the search, save the list of structures to a list file, and output the structures to a structure-data file (SDFile). The MACCS database was a proprietary flat database system in which data of a given type, say, formula, was stored in a given file, indexed by the compound ID number.

Search Queries. For all types of chemical representation, there are query representations that can be applied to a database to return a list of structures which match or "fit"the query, or that the query "hits" in the database. The same chemical drawing programs that are used to input structures can commonly be used to input chemical structure queries. These drawing programs currently include several programs in the commercial and public domains (44). A comparison of pop-... 

Supplementary Material Available A listing of structure factors (6 pages). Ordering information is given on any current masthead page. 

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