摘要:
A method comprises forming a reaction mixture comprising a terephthalate polyester, a glycol comprising 2 to 5 carbons, and an amidine organocatalyst; and heating the reaction mixture at a temperature of about 120° C. or more to depolymerize the terephthalate polyester, thereby forming a terephthalate reaction product comprising a monomeric dihydroxy terephthalate diester; wherein the terephthalate reaction product contains terephthalate oligomers in an amount less than the amount of terephthalate oligomers that would result from i) substituting the amidine organocatalyst with an equimolar amount of a guanidine catalyst and ii) depolymerizing the terephthalate polyester under otherwise identical reaction conditions.
摘要:
A method comprises forming a reaction mixture comprising a terephthalate polyester, a glycol comprising 2 to 5 carbons, and an amidine organocatalyst; and heating the reaction mixture at a temperature of about 120° C. or more to depolymerize the terephthalate polyester, thereby forming a terephthalate reaction product comprising a monomeric dihydroxy terephthalate diester; wherein the terephthalate reaction product contains terephthalate oligomers in an amount less than the amount of terephthalate oligomers that would result from i) substituting the amidine organocatalyst with an equimolar amount of a guanidine catalyst and ii) depolymerizing the terephthalate polyester under otherwise identical reaction conditions.
摘要:
A salt catalyst comprises an ionic complex of i) a nitrogen base comprising one or more guanidine and/or amidine functional groups, and ii) an oxoacid comprising one or more active acid groups, the active acid groups independently comprising a carbonyl group (C═O), sulfoxide group (S═O), and/or a phosphonyl group (P═O) bonded to one or more active hydroxy groups; wherein a ratio of moles of the active hydroxy groups to moles of the guanidine and/or amidine functional groups is greater than 0 and less than 2.0. The salt catalysts are capable of catalyzing ring opening polymerization of cyclic carbonyl compounds.
摘要:
A salt catalyst comprises an ionic complex of i) a nitrogen base comprising one or more guanidine and/or amidine functional groups, and ii) an oxoacid comprising one or more active acid groups, the active acid groups independently comprising a carbonyl group (C═O), sulfoxide group (S═O), and/or a phosphonyl group (P═O) bonded to one or more active hydroxy groups; wherein a ratio of moles of the active hydroxy groups to moles of the guanidine and/or amidine functional groups is greater than 0 and less than 2.0. The salt catalysts are capable of catalyzing ring opening polymerization of cyclic carbonyl compounds.
摘要:
A method and apparatus for capturing annotations about database material in a way that allows queries with conditions or predicates on both the database material and the annotations. Database material may be text, computer programs, graphics, audio, spreadsheets, or any other material which may be stored and indexed. Database material may be in one or multiple sources, and annotations may be stored together with the original material or in a separate store. Annotations can be used to capture information such as additional facts about the database material, the opinions and judgments of experts about the database material, and/or links to other related material. Annotations may be captured in a structured form to enhance queryability and semantic interpretation.
摘要:
A method and apparatus for capturing annotations about database material in a way that allows queries with conditions or predicates on both the database material and the annotations. Database material may be text, computer programs, graphics, audio, spreadsheets, or any other material which may be stored and indexed. Database material may be in one or multiple sources, and annotations may be stored together with the original material or in a separate store. Annotations can be used to capture information such as additional facts about the database material, the opinions and judgments of experts about the database material, and/or links to other related material. Annotations may be captured in a structured form to enhance queryability and semantic interpretation.
摘要:
The virtual screening of a database of molecules is based on explicit three-dimensional molecular superpositions. The torsional flexibility of the database molecules is taken fully into account, and an arbitrary number of conformation-dependent molecular features may be considered. A fragmentation-reassembly approach is utilized, which allows for an efficient sampling of the conformational space. A fast clique-based pattern-matching algorithm generates alignments of pairs of adjacent molecular fragments on the (rigid) query molecule that are subsequently reassembled to complete database molecules. Using conventional molecular features (hydrogen bond donors and acceptors, charges, and hydrophobic groups), it is possible to rapidly produce accurate alignments of medium-sized drug-like molecules. Examples with a test database containing a diverse set of 1780 drug-like molecules (including all conformers) show that average query processing times of the order of 0.1 seconds per molecule can be achieved on a PC, depending on the size of the query molecule.
摘要:
A method and apparatus for capturing annotations about database material in a way that allows queries with conditions or predicates on both the database material and the annotations. Database material may be text, computer programs, graphics, audio, spreadsheets, or any other material which may be stored and indexed. Database material may be in one or multiple sources, and annotations may be stored together with the original material or in a separate store. Annotations can be used to capture information such as additional facts about the database material, the opinions and judgments of experts about the database material, and/or links to other related material. Annotations may be captured in a structured form to enhance queryability and semantic interpretation.