Yuzuru Fujiwara

NMR conformational analysis of chain molecules using the local interaction model. I. 2,4,‐disubstituted pentanes

The practical usefulness of the local interaction model in the NMR conformational analysis of chain molecules is demonstrated for 2,4‐disubstituted pentanes, CH3CHRCH2CHRCH3, which are model compounds of vinyl polymers. In the present treatment based on this model, the relative energies of all the possible conformers are expressed as sums of the five kinds of intramolecular interaction energy parameters, which are determined to reproduce the observed temperature dependence of the vicinal spin‐spin coupling constants between the methine and methylene protons. The method was applied to the analyses of pentane‐2,4‐diol, 2,4‐dichloropentane and 2,4‐diphenylpentane on the basis of the NMR data in the literature. The energy parameters, the conformer energies, and the populations were determined. The observed solvent effect in pentane‐2,4‐diol can be interpreted directly as the variation in the intramolecular interaction energy between the two hydroxyl groups, −1.0 to 0.8 kcal mol−1. In the analysis of this solv...

Superfine Particle Magnetite

Superfine particle magnetites were prepared in crosslinked polyvinylalcohol (PVA) media. PVA gel prepared by Co⁶⁰ gamma irradiation was immersed in a mixed aqueous solution of ferric and ferrous chlorides and then in sodium hydroxide. Measurements of Fe₃O₄ concentration, residual magnetization, and coercive force were made. Data are presented in tabular form. (L.N.N.)

Decomposition—an approach for optimizing queries including ADT functions

In order to extend the database application to CAD/CAM and other engineering areas, several systems have employed ADTs [&lo]. This extension introduces a new dimension to query optimization. Conventional query processing focuses on the cost of input and output between main and secondary memory. In contrast, to process queries involving ADT functions, the computing cost of the ADT functions must be taken into consideration, since it is often the case that they dominate the I/O cost. For example, in a chemical DBMS, to represent the structure of chemical compounds, the support of ADT “GRAPH” is necessary. Accordingly, ADT functions such as displaying a graph, calculating the number of nodes of a graph, and comparing two graphs, etc., are required. Suppose that an ADT function isomorphic is defined to determine isomorphism between two graphs. The function isomorphic is

A method for the machine detection of near equivalence of major substructures in a molecule

The use of the concept of near equivalence of substructures in a computer program concerned with organic synthesis requires a concrete definition of «nearness» and an efficient method for implementing the concept. Such a method has been devised and its use is described and examples are given.

A graph theory data base for storage of chemical structures organized by the block-cutpoint tree technique

Abstract The method presented for organizing a data base according to graph theory, is based on representation of chemical structures in terms of BCT (block-cutpoint tree). It is useful for quick substructure searches and is convenient for structure generation. The data base consists of four files: a master file, a bit sequence file of fixed length records which gives block components of compounds, a BCT file which gives the BCT structures of compounds, and a block file which specifies the blocks. These files are organized recursively and hierarchally, which simplifies the processing of structural information on compounds.

Database support for solid modeling

Geometric solid modeling plays one of the most important roles in CAE (Computer Aided Engineering) activities. In order that geometric solid modeling functions sufficiently in the CAE environment, an EDBMS (Engineering Database Management System) supporting solid modeling is highly desirable. In this paper we present a new approach to the design of a geometric solid database system. In the proposed approach an EDBMS with capability of object-oriented accessing and manipulation is developed, and a solid sharing model that is a scheme for representing and manipulating a collection of interrelated solids is proposed. The solid sharing model is used as a basis for designing and manipulating a solid database managed by the EDBMS. Also explored is a mechanism for supporting a long transaction which generates many intermediate designs.

Learning system for automatic structural analysis of mass spectra

A computer-assisted mass spectral interpretation system with a learning mechanism is described. The set of correspondences between substructure and spectral component (CSSC) is used for interpreting mass spectra, CSSC is generated, renewed, and improved automatically in the system. This self-organization of CSSC is “learning”. Chemical structures are represented in terms of blocks, which facilitates the learning process.

An evolutional and conceptual structure based method of analogical reasoning

A computational method of analogical reasoning is developed based on a conceptual network which evolves as a series of reasoning tasks are processed. More specifically, given a pair of concepts whose logical relationship is unknown, the method first retrieves pairs of concepts which are similar to the given one and whose logical relationships are well-known, then infers the unknown relationship from the similarities among the retrieved and given pairs of concepts, and finally adds the inferred relationship to the original conceptual network. The retrieval of the similar pairs turns out to require the identification of isomorphic substructures of the network, which is a combinatorial and time-consuming task. Two strategies are presented to address this problem. First, the conceptual network is structured to facilitate the combinatorial substructure matching, and secondly an evolutional approach is incorporated into the method that minimizes the computational efforts in the long series of reasoning tasks. Our method is applied to a large chemical database system comprised of instances of organic compounds and reactions.

Analogical Reasoning of Organic Reactions Based on the Structurized Compound-Reaction Diagram

As the number of chemical compounds identified increases as well as the amount of the associated knowledge of their properties and reactions, the necessity for developing intelligent database or expert systems is correspondingly expanding. Such systems are often required to analogically reason new reactions by recognizing the similarities of compounds and reactions.

A method of using semijoins to optimize queries with ADT functions

ADTs (A bstYYzct Data Types) have been known as a promising feature for making the relational database meet the requirements of CAD/CAM applications. This extension has brought a new dimension to query optimization. Based on the belief that the execution costs of selections and projects are inexpensive, conventional query optimization methods focus only on minimizing the execution costs of joins. However when a selection involving ADT functions(briefly, AD 2’ selection) is included in a query, the computation cost of the ADT functions may become an important factor to the totaJ execution cost of the query and therefore must be taken into consideration. The reason is that the evaluation of an ADT function is often computationally expensive. Therefore the conventional query optimization strategy is no longer suitable for such queries. We need a new query optimization strategy focusing on ADT selections.