In order to study the structure-activity relationship between 13C-NMR chemical shifts and the carcinogenicity of eleven polycyclic aromatic hydrocarbons (PAH), a neural network analysis was performed with the reconstruction method which is a pre-learning method and the relationship between input and output data is suggested. The neural network applied is a standard perceptron type with three layers. In this analysis 13C-NMR chemical shifts are treated as structuraldata and the carcinogenicity as output. It has been reported that electron density in three regions, i.e., L, K and bay regions has strong correlation with the carcinogenicity of PAH. Importance of these three regions is suggested by reconstructing the weight matrices.
A file conversion program for data formats of molecular structures in chemistry MOLCONV was renewed. The aim of MOLCONV is applied in dealing with various data formats with flexibility. A macro-language and its interpreter for file conversion procedures are employed for this purpose. The new MOLCONV was provided with only conversion function for an independent program, at first. The old was one of the applications, which consisted of structure input, display, etc., for chemistry. Secondly, in addition to the conventional way of step by step depending on menu selection, the way of a command line procedure was adopted in the new program. At last the interpreter was fortified. This paper presents the concept of MOLCONV and the modified MOLCONV.
In cellular energy transformation, ATP plays a central role in the presence of divalent cations such as Mg2+. A software is presented for displaying the free energy changes for the hydrolysis of ATP as a contour diagram on a personal computer. This software also shows the values of the concentration of ATP-ion complex under various pH.
A Lipid-Membrane Modeling System involving intermolecular energy calculation has been developed, and applied for prediction of crystal structures of lipids. In the case of two kinds of lipid molecules, the obtained structure parameters for the crystals are in good agreement with the values previously reported using single crystal analyses.
It is difficult for us to imagine the three-dimensional appearance of atomic orbitals from the formulae of the solution of Schroedinger wave equation. In this paper, we would like to report the visualization of three-dimensional contour surfaces of a series of hydrogen atomic orbital functions using a software called AVS (Application Visualization System) on an EGWS (Engineering Graphic Workstation), IRIS INDIGO XS24 or TITAN 3000. From these drawings, the relationship between the number of lobes and nodes of atomic orbitals was derived.