Structure relations

Elastic energy release due to subcritical crack growth is one recognized source of structure-related AE within its acknowledged lunitations, AEBIL provides a viable means of early on-line deteetion and localization of stable crack propagation. 

Beilstein and Gmelin are the world s largest factual databases in chemistiy. Beil-stein contains facts and structures relating to organic chemistry, whereas Gmelin provides information on inorganic, coordination, and organomctallic compounds. 

Another objective is to discuss briefly recent and major trends in the field of methine dyes color. Indeed, because of its relatively simple structure, the thiazole ring has been chosen in the past for studying color-structure relations. Using Brooker s basicity concepts (5), numerous valuable attempts in different countries succeeded in establishing semiempirical rules for explaining the effects of structural changes on color. 

Deviation includes, in fact, the summation of steric and electronic effects, and basicity is somewhat a useful predictor for properties of complex dyes (solvent sensitivity, isomeric forms of trinuclear dyes) and gives also semiquantitative data for color structure relation (atomic)... 

Naturally occurring compounds with carbon-metal bonds are very rare The best example of such an organometallic compound is coenzyme Bi2 which has a carbon-cobalt ct bond (Figure 14 4) Pernicious anemia results from a coenzyme B12 deficiency and can be treated by adding sources of cobalt to the diet One source of cobalt IS vitamin B12 a compound structurally related to but not identical with coen zyme B12... 

Research in physiology carried out in the 1930s established that the lipid fraction of semen contains small amounts of substances that exert powerful effects on smooth mus cle Sheep prostate glands proved to be a convenient source of this material and yielded a mixture of structurally related substances referred to collectively as prostaglandins We now know that prostaglandins are present m almost all animal tissues where they carry out a variety of regulatory functions... 

Homologous series (Section 2 9) Group of structurally related substances in which successive members differ by a CH2 group... 

SKIP produces its effects through two classes of GPCR, SRIF-1 and SRIF-2 that are structurally related to cloned opiate receptors. The agonists,... 

Saponins. Although the hypocholesterolemic activity of saponins has been known since the 1950s, thek low potency and difficult purification sparked Htde interest in natural saponins as hypolipidemic agents. Synthetic steroids (292, 293) that are structurally related to saponins have been shown to lower plasma cholesterol in a variety of different species (252). Steroid (292) is designated CP-88,818 [99759-19-0]. The hypocholesterolemic agent CP-148,623 [150332-35-7] (293) is not absorbed into the systemic ckculation and does not inhibit enzymes involved in cholesterol synthesis, release, or uptake. Rather, (293) specifically inhibits cholesterol absorption into the intestinal mucosa (253). As of late 1996, CP-148,623 is in clinical trials as an agent that lowers blood concentrations of cholesterol (254). 

DESIGN OF INHIBITORS FROM A SERIES OF STRUCTURALLY RELATED COMPOUNDS... 

Both and H NMR data are also available for a range of 2(l//)-pyrazinones which are structurally related to the aspergillic acids (76T655). 

Numerous dyes structurally related to the safranines, such as the eurodines, e.g. (141), the indulines, e.g. (142), the nigrosines (143) and aniline black, a pigment of unknown structure used in the printing industry, are well known and a detailed account of their chemistry and applications has been presented (57HC(ll)l). 

Examination of the pyrazino[2,3-rf]pyrimidine structure of pteridines reveals two principal pathways for the synthesis of this ring system, namely fusion of a pyrazine ring to a pyrimidine derivative, and annelation of a pyrimidine ring to a suitably substituted pyrazine derivative (equation 76). Since pyrimidines are more easily accessible the former pathway is of major importance. Less important methods include degradations of more complex substances and ring transformations of structurally related bicyclic nitrogen heterocycles. 

The most rational way to classify structures related to pyrazole is to take into account the number of double bonds present, either endo- or exo-cyclic. An endocyclic double bond can formally be considered part of a benzene ring in this context. 

A. Identifying Known Protein Structures Related to the Target Sequence... 

G Vriend, C Sander, PFW Stouten. A novel search method for protein sequence-structure relations using property profiles. Protein Eng 7 23-29, 1994. 

The World Wide Web has transformed the way in which we obtain and analyze published information on proteins. What only a few years ago would take days or weeks and require the use of expensive computer workstations can now be achieved in a few minutes or hours using personal computers, both PCs and Macintosh, connected to the internet. The Web contains hundreds of sites of Interest to molecular biologists, many of which are listed in Pedro s BioMolecular Research Tools (http // www.fmi.ch/biology/research tools.html). Many sites provide free access to databases that make it very easy to obtain information on structurally related proteins, the amino acid sequences of homologous proteins, relevant literature references, medical information and metabolic pathways. This development has opened up new opportunities for even non-specialists to view and manipulate a structure of interest or to carry out amino-acid sequence comparisons, and one can now rapidly obtain an overview of a particular area of molecular biology. We shall here describe some Web sites that are of interest from a structural point of view. Updated links to these sites can be found in the Introduction to Protein Structure Web site (http // WWW.ProteinStructure.com/). 

Obtaining information on a material s electronic band structure (related to the fundamental band gap) and analysis of luminescence centers Measurements of the dopant concentration and of the minority carrier diffusion length and lifetime... 

RAIRS spectra contain absorption band structures related to electronic transitions and vibrations of the bulk, the surface, or adsorbed molecules. In reflectance spectroscopy the ahsorhance is usually determined hy calculating -log(Rs/Ro), where Rs represents the reflectance from the adsorhate-covered substrate and Rq is the reflectance from the bare substrate. For thin films with strong dipole oscillators, the Berre-man effect, which can lead to an additional feature in the reflectance spectrum, must also be considered (Sect. 4.9 Ellipsometry). The frequencies, intensities, full widths at half maximum, and band line-shapes in the absorption spectrum yield information about adsorption states, chemical environment, ordering effects, and vibrational coupling. 

Simmons, J.H.W., Radiation Damage in Graphite, Pergamon Press, Oxford, 1965. Kelly, B.T. and Burchell, T.D., Structure-related property changes in polycrystallinc graphite under neutron irradiation, Carbon, 1994, 32, 499 505. 

The molecular aspects of. interdiffusion of linear entangled polymers M > Mc cmi fng elcffft g (S pofymer interfaces are summarized in Table 1 [1]. The regJt tion( i qraiq piS 1the interface structure relations in Table 1 hav gbp p... 

The layers in the plate-like structure of talc are Joined by very weak van der Waals forces, and therefore delamination at low shear stress is produced. The plate-like structure provides high resistivity, and low gas permeability to talc-filled polymers. Furthermore, talc has several other structure-related unique properties low abrasiveness, lubricating effect, and hydrophobic character. Hydrophobicity can be increased by surface coating with zinc stearate. 

A second example of this strategy is the retrosynthetic simplification of 184 via the equivalent 185 by subsequent application of the tactical combination of retroaldol and [2 + 2] photocycloaddition transforms.50 Various targets which are structurally related to 184 have also... 

Retrosynthetic analysis of antheridic acid produced a totally different plan of synthesis from that which had been employed for the structurally related target gibberellic acid. The synthesis of antheridic acid, which included a number of novel steps, allowed definitive assignment of structure and revised stereochemistry at C(3). 

Finally, Vogtle and his coworkers have prepared a number of cascade molecules which are structurally related to the aforementioned systems. These are repeating ring units of increasingly large cavity size and are prepared by repetitive synthetic procedures. Typically, an amine is cyanoethylated, the nitrile reduced to an amine which may then be further cyanoethylated and reduced or cyclized with a diacid halide. The rather elaborate scheme is illustrated in ref. 61 and examples of the structural type are shown in Table 8.4. 

The assumption of these conjugated double bonds makes possible a tetracyclic nucleus which accords with the suggestion previously made by the authors that these alkaloids might be structurally related to the diterpenes. It may also be noted that one of the nitric acid oxidation products of pseudaconitine has been recorded as unexpectedly giving a pyrrole reaction on destructive distillation. ... 

The followmg types of studies will not be presented individually but may have contnbuted supportmg data to coverage by compound type conformational analyses [23 24, 25, 26 27], fluoropolymers [28, 29, 30 31, 32], solid-state NMR [ii], and solvent effects [34 35, 36, 37] Many excellent articles with m-depth NMR interpretation of one specific compound or of a small, structurally related group of compounds can be found in the chemical hterature A few of these, not incorporated elsewhere in this secUon are referenced here carbonyl fluondes [JS 39 40], fluoropropanes [41 42, 43], fluorocyclopropanes [44, 45 46], fluorobutanes [47], perfluorocyclobutanone [48], fluorohexanes [49], and vinyl fluondes [50, 51 52, 53, 54]... 

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