Abstract. This paper describes an evolution of the 3store RDF storage system, extended to provide a SPARQL query interface and informed by lessons learned in the area of scalable RDF storage.
Present chemical data storage methodologies place many restrictions on the use of the stored data. The absence of sufficient high-quality metadata prevents intelligent computer access to the data without human intervention. This creates barriers to the automation of data mining in activities such as quantitative structure-activity relationship modelling. The application of Semantic Web technologies to chemical data is shown to reduce these limitations. The use of unique identifiers and relationships (represented as uniform resource identifiers, URIs, and resource description framework, RDF) held in a triplestore provides for greater detail and flexibility in the sharing and storage of molecular structures and properties.
The cation complexing abilities of a series of p-tert-butylcalix[4]arenes bearing ligating ester groups in the cone conformation have been assessed by stability constant measurements in methanol and extraction studies from water into dichloromethane. The cations studied were Na+ and K+ and variations in the ester function (C0,R) included R = methyl, ethyl, n-butyl, tert-butyl, benzyl, p henyl, p henacyl, met hoxyet hyl , trif luoroet hyl, met hylt h ioet hyl and prop-2ynyl. The effect of replacing one or two ester functions in the tetraethyl ester by methyl ester, carboxylic acid, ketone and amide functions was also studied. Selectivities for Na' relative to K+ in stability constants range from 2 to 2500, the phenacyl derivative having the highest selectivity. X-Ray diffraction analysis was used to probe the conformation of the trifluoroethyl ester 11. Crystals of I 1 are monoclinic, space group P2,/n, in a cell of dimensions a = 13.987( 2), b = 16.194(3), c = 27.630(5) A; p = 98.70(1)"; R = 0.077 for 3172 observed data. The compound possesses a distorted cone conformation.
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