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Biomedical subjects

A H Lipkus

Publications and source records attributed to A H Lipkus.

5 recordsLinked to original sources
PubMed1990

Evaluation of infrared spectroscopy as a bacterial identification method.

A study motivated by the recent revival of interest in the use of IR spectroscopy to identify bacteria is reported. A library of FT-IR spectra of dried bacterial films was complied using 16 different strains. A test set was compiled from spectra of the same strains grown several months later. The test set was quantitatively compared with the library on the basis of spectral similarity in the region 980-1190 cm-1. Six of the strains in the test set were not matched with the correct strain in the library despite efforts to reproduce the conditions under which cells were grown and prepared. The results suggest that reproducibility of the bacterial spectra is a potential difficulty that must be addressed by any attempts to develop FT-IR spectroscopy as a bacterial identification method.

Bacteria↗
PubMed1988

Automated classification of candidate structures for computer-assisted structure elucidation.

In computer-assisted structure elucidation, a large number of candidate structures for the unknown compound can be generated. A computer program designed to aid in the recognition of significant differences between these structures is described. The goal of the program is to group the candidates into meaningful classes with a minimum of input from the user; each class is distinguished by a substructure its members have in common. A computational approach is developed based on the combinatorial problem of set covering. The program evaluates its results using an information-theoretical criterion. An application of the program to a real-word structure problem is presented.

Chemical Phenomena↗
PubMed1985

Combinatorial problems in computer-assisted structural interpretation of carbon-13 NMR spectra.

Combinatorial problems posed by a method for computer-assisted structural interpretation of 13C NMR spectra based upon fragments consisting of a carbon atom and its alpha neighbors are discussed. The basic problem of generating all structures consistent with a set of inferred fragments that contains mutually exclusive alternatives is divided into two parts: generation of combinations of fragments and exhaustive assembly of each combination into molecules. Algorithmic solutions to both of these problems are presented in detail.

Carbon Isotopes↗
PubMedDate not supplied

Exploring chemical rings in a simple topological-descriptor space.

A new method for organizing chemical rings based on their topology is presented. It uses three simple descriptors that characterize separate aspects of ring topology. These descriptors are integers and can thus be interpreted as the coordinates of discrete cells in a three-dimensional space. The descriptor values of any ring topology correspond to the coordinates of some cell. A database of rings can be distributed in this descriptor space by assigning each of them to the corresponding cell. This approach is applied to a database of 40 182 different ring topologies, derived from a comprehensive collection of chemical rings extracted from the CAS Registry File. This database is distributed among 7387 cells, and the population statistics and spatial distribution of these cells are discussed. An examination of selected cells shows that ring topologies which are similar tend to be close together in descriptor space. Some results of using this space to study ring diversity are presented. It is found that the distribution of the ring-topology database is not highly compact but has many significant voids. It is also found that the distribution of medicinally relevant rings in this space shows the influence of certain structural constraints on drug molecules.

Journal Article↗