We developed a molecular graphics system, named “Modrast-P”, which reads coordinates in the Protein Data Bank of Brookhaven National Laboratory format (PDB). This graphics system displays three-dimensional structures of proteins and nucleic acids with various representations and shows molecular models clipped by single plane, double plane, and a cylinder defined arbitrarily. This system runs on the OpenWindows of Sun Microsystems workstation and most functions of it can be operated easily by a mouse or buttons. We also developed an information retrieval system which can seek the target file in CD-ROM by author name, keyword, or amino acid sequence.

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SSCAI, a BASIC program for CAI utilizing spreadsheet data files, was developed. The program enables the users to browse or search spreadsheet data files easily, and to draw two-dimensional graphs (see Fig. 5-7) or three-dimensional graphs (Fig. 4) from numerical data. Regression analysis (see Fig. 6), spline interpolation (Fig. 7) and multiple regression analysis (Fig. 8) can be conducted, too. Furthermore, for the purpose of chemical education, if appropriate types of data files are available, molecular graphics, visible spectra, or organic conceptual diagrams can be shown on a display (see Fig. 3 and 9).
The users can practice CAI in a classroom with their own data and/or the collection of data files attached to the program, which includes data on properties of chemical elements, molecules of odours, agricultural chemicals, drugs and others.
The program and the data files can be obtained free of charge from the software library of the Chemical Software Society of Japan, the NIFTY-Serve Bulletin Board System, or the Web at http : //www2d.meshnet.or.jp/chem_env/lib/lib.html.

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A Self-organized network model for high-speed learning was included in the perceptron type Neural network simulator for structure-activity correlation of molecules : Neco. The performance of the Self-organized network model was compared with that of perceptron using twodimensional exclusive OR problem and the relationship between ¹³C-NMR shift and the conformation of norbornane. For practical use, the speed for convergence of the Self-organized network is almost four times faster than that of perceptron though perceptron gives higher order convergence. In the case of ¹³C-NMR shift and conformation of norbornane, a Self-organized network seems to show strong nonlinear classification in comparsion with perceptron.

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We investigated the application of an X-ray diffraction method to determine ammonium nitrate in dynamite more simply and accurately without a separation procedure. In this method, organonitro compounds were removed from the sample using diethyl ether for safety, and the residue was dried. Next, the sample was directly measured by the X-ray diffraction method. The determination of ammonium nitrate content was calculated by multivariate analysis such as cluster analysis and principal component analysis. The calculated values were in fair agreement with theoretical values.

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