SMARTS isotope

Using this isotope labeling approach, metabolites in human plasma have been quantified (38) and altered metabolites have been detected in urine that are due to metabolic disorders such as tyrosinemia type II, argininosuccinic aciduria, homocystinuria, and phenylketonuria (20). Most recently, a smart isotope tag, 15N-cholamine, has been developed for effective detection of the same metabolites using both NMR and MS methods. This approach maximizes the combined strengths of two powerful analytical techniques for a variety of metabolomics applications. 15N-cholamine possesses dual characteristics an NMR-sensitive heteronuclear isotope with good chemical shift dispersion and a permanent charge that improves MS sensitivity (48). 

Roberts MS, Smart PL, Hawkesworth CJ, Perkins WT, Pearee NJP (1999). Trace element variations in coeval Holocene speleothems from GB Cave, southwest England. The Holocene 9 138-139 Robinson LF, Henderson GM, Slowey NC (2002) U-Th dating of marine isotope stage 7 in Bahamas slope sediments. Earth Planet Sci Lett 196 175-187... 

Crystal structure modification, in smart materials, 22 707 CS (riot control agent), 5 823-824 CS2, formation in the Claus furnace, 23 605. See also Carbon disulfide C-scan images, 17 424, 429 Cs isotopes, decay of, 21 303-304. 

Molecular hydrogen, 23 759 Molecular imprinting, 6 397 Molecular interactions, 25 103 Molecular interaction theories, 24 38 Molecular Laser Isotope Separation (MLIS) process, 25 416 417 Molecular level machine, 2 7 58 Molecularly imprinted plastics (MIPs) smart, 22 717)... 

One radioactive isotope of yttrium, yttrium-90, has some important practical applications. The isotope is combined with other substances to produce smart drugs. Smart drugs are drugs that detect, attack, and destroy only certain, very specific kinds of cells, such as those found in cancerous tissue. One advantage of using yttrium-90 is that it is easy to obtain. It is produced when another radioactive isotope (strontium-90) breaks down. Strontium-90 is a by-product of nuclear reactions that occur in nuclear power plants. 

It is possible to specify the isotope of any atom in a SMILES string. This is generally not necessary because the most common isotope is simply assumed. But if, for example, a database contains information about 13C, this can be readily encoded into the SMILES using [13C] instead of simply C. The [13C] atom is considered different from the normal C atom in a SMILES. A direct lookup using canonical SMILES will not locate isotopes of the same structure. A substructure search using the matches function will locate isotopes. This is because the match function uses SMARTS to specify the desired substructure. 

Isotopes can be used in SMARTS. If no isotope number is specified in SMARTS, any isotope of the atom will match. For example, select matches ( N[13C], C ) will return true. However, select matches( SNC[13C] ) will return false. When a specific isotope is mentioned in SMARTS, then only that isotope number will match. 

Turro NJ. From boiling stones to smart crystals supramolecular and magnetic isotope control of radical-radical reactions in zeolites. Acc Chem Res 2000 33 637. 

NRG (1987) Radiogenic age and isotopic studies report 1. National Research Council of Canada NRC Research, Ottawa O Conner DJJ, Smart RS, Sexton BA (2003) Surfece analysis methods in materials science. Springer, New York Odian G (2004) Principles of polymerization. Wiley, New York Oss CJ (1994) Interfadal forces in aqueous media. c lDekker, New York Parfitt CD, Sing KSW (1976) Characterization of powder surfoces. Academic, London... 

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