Phototoxicity is of increasing concern since modern lifestyle is often associated with exposure to sunlight. Therefore characterizing the phototoxic potential of a compound early in its development is of utmost interest, especially for compounds likely to undergo sunlight exposure in skin. Traditioanly the phototoxic effect is modeled by using the E HOMO -E LUMO gap (energy difference between t...

This paper describes the problem of modelling toxicity of environmental pollutants using molecular descriptors from a systems theoretical viewpoint. It is shown that current toxicity modelling problems systematically incorporate very high levels of noise a priori. By means of a set of individual and combined models self-organised by KnowledgeMiner from a high-dimensional molecular descriptor da...

BACKGROUND Molecular descriptors are essential for many applications in computational chemistry, such as ligand-based similarity searching. Spherical harmonics have previously been suggested as comprehensive descriptors of molecular structure and properties. We investigate a spherical harmonics descriptor for shape-based virtual screening. METHODOLOGY/PRINCIPAL FINDINGS We introduce and valid...

Classical quantitative structure-properties relationship (QSPR) statistical techniques unavoidably present an inherent paradoxical computational context. They rely on the definition of a Gram matrix in descriptor spaces, which is used afterwards to reduce the original dimension via several possible kinds of algebraic manipulations. From there, effective models for the computation of unknown pro...

The aim of this paper is to analyze the undamped second order descriptor systems to show the possibility of transform an undamped second order descriptor system to a pure first order descriptor system ,on different ways, while stating some of its benefits. Meanwhile we will introduce pure first order systems and undamped second order systems and indicate that under some assumptions every undamp...

BACKGROUND The inverse-QSAR problem seeks to find a new molecular descriptor from which one can recover the structure of a molecule that possess a desired activity or property. Surprisingly, there are very few papers providing solutions to this problem. It is a difficult problem because the molecular descriptors involved with the inverse-QSAR algorithm must adequately address the forward QSAR p...

the dispersibility of graphene is modeled as a mathematical function of the molecular structure of solvent represented by simplified molecular input-line entry systems (smiles) together with the graph of atomic orbitals (gao). the gao is molecular graph where atomic orbitals e.g. 1s1, 2p4, 3d7 etc., are vertexes of the graph instead of the chemical elements used as the graph vertexes in the tra...

The paper presents and illustrates a method which uses numerical integration of the van der Waals envelope(s) to calculate with desired accuracy the molecular van der Waals volume and the three-dimensional molecular shape descriptor defined as the twin-number [OV(a, /?); NOV(/?, a)], where OV and NOV represent the overlapping and, respectively, the nonoverlapping van der Waals volumes of the mo...