In Silico Prediction of Physicochemical Properties

This report provides a critical review of computational models, and in particular(quantitative) structure-property relationship (QSPR) models, that are available for the prediction of physicochemical properties. The emphasis of the review is on the usefulness of the models for the regulatory assessment of chemicals, particularly for the purposes of the new European legislation for the Registration, Evaluation, Authorisation and Restriction of CHemicals (REACH), which entered into force in the European Union (EU) on 1 June 2007. It is estimated that some 30,000 chemicals will need to be further assessed under REACH. Clearly, the cost of determining the toxicological and ecotoxicological effects, the distribution and fate of 30,000 chemicals would be enormous. However, the legislation makes it clear that testing need not be carried out if adequate data can be obtained through information exchange between manufacturers, from in vitro testing, and from in silico predictions. The effects of a chemical on a living organism or on its distribution in the environment is controlled by the physicochemical properties of the chemical. Important physicochemical properties in this respect are, for example, partition coefficient, aqueous solubility, vapour pressure and dissociation constant. Whilst all of these properties can be measured, it is much quicker and cheaper, and in many cases just as accurate, to calculate them by using dedicated software packages or by using (QSPRs). These in silico approaches are critically reviewed in this report.JRC.I.3-Toxicology and chemical substance

Predicción del punto de fusión de indoles con base en la estructura molecular usando redes neuronales artificiales

Mediante la aplicación del método de relación cuantitativa de estructura propiedad se determinó un modelo para predecir la temperatura del punto de fusión de indoles a partir de su estructura molecular (n = 86). Usando los programas de computadora Gaussian 98 y PCDM 2.0, se calcularon una serie de descriptores moleculares; descriptores electrónicos, topológicos y geométricos. Para la elaboración del modelo de predicción se empleó la regresiónlinear múltiple entre los descriptores moleculares y la temperatura de los puntos de fusión de los indoles presentes en la base de datos. Dando como resultados un coeficiente de determinación (R2) y un error estándar de estimación (EEE) de 0.73 y 27.42°C respectivamente. Por medio de una red neuronal retropropagación (5: 4: 1) se optimizó el modelo de regresión lineal múltiple, pudiéndose incluir relaciones no lineales entre la estructura molecular y la temperatura del punto de fusión de los indoles, obteniendo mejores resultados en la predicción del puntode fusión para el grupo de entrenamiento (R2 =0.9978) y el grupo de validación (R2 =0.9987). El error cuadrático promedio (MSE) asociado al grupo de entrenamiento y de validación para el modelo de con la red fue 0.006 y 0.006 respectivamente

Energy Materials Coordinating Committee (EMaCC): Fiscal year 1996. Annual technical report

The DOE Energy Materials Coordinating Committee (EMaCC) serves primarily to enhance coordination among the Department`s materials programs and to further effective use of materials expertise within the Department. These functions are accomplished through the exchange of budgetary and planning information among program managers and through technical meetings/workshops on selected topics involving both DOE and major contractors. In addition, EMaCC assists in obtaining materials-related inputs for both intra- and interagency compilations. The EMaCC reports to the Director of the Office of Energy Research in his or her capacity as overseer of the technical programs of the Department. This annual technical report is mandated by the EMaCC terms of reference. This report summarizes EMaCC activities for FY 1996 and describes the materials research programs of various offices and divisions within the Department

Modellierung PBPK-relevanter Verteilungskoeffizienten organischer Stoffe

Drei Verteilungskoeffizienten, die für physiologie-basierte Pharmakokinetik (PBPK)-Modelle relevant sind, wurden mit verschiedenen Ansätzen modelliert. Für den Blut/Luft-Verteilungskoeffizienten wurde ein auf linearen Solvatations-Energie-Beziehungen (LSER) beruhendes Literaturmodell angewendet und diskutiert. Mit einer schematischen Aufteilung des Blutkompartiments in Wasser und einen organischen Teil wurde der Blut/Luft-Verteilungskoeffizient mit einer linearen Regression von anderen Verteilungskoeffizienten vorhergesagt. Zusätzlich wurde ein Fragmentmodell entwickelt. Der Fett/Luft-Verteilungskoeffizient wurde mit dem LSER-Ansatz und mit anderen Verteilungskoeffizienten modelliert. Der Koeffizient Fett/Blut wurde aus den ersten beiden errechnet. Da der inverse dimensionslose Henry-Koeffizient Wasser/Luft-Verteilungskoeffizient bei der Blut/Luft-Modellierung zum Einsatz kommt und dieser aus dem Dampfdruck und der Wasserlöslichkeit gewonnen werden kann, wurde der Dampfdruck ebenfalls modelliert

Biomass Processing for Biofuels, Bioenergy and Chemicals

Biomass can be used to produce renewable electricity, thermal energy, transportation fuels (biofuels), and high-value functional chemicals. As an energy source, biomass can be used either directly via combustion to produce heat or indirectly after it is converted to one of many forms of bioenergy and biofuel via thermochemical or biochemical pathways. The conversion of biomass can be achieved using various advanced methods, which are broadly classified into thermochemical conversion, biochemical conversion, electrochemical conversion, and so on. Advanced development technologies and processes are able to convert biomass into alternative energy sources in solid (e.g., charcoal, biochar, and RDF), liquid (biodiesel, algae biofuel, bioethanol, and pyrolysis and liquefaction bio-oils), and gaseous (e.g., biogas, syngas, and biohydrogen) forms. Because of the merits of biomass energy for environmental sustainability, biofuel and bioenergy technologies play a crucial role in renewable energy development and the replacement of chemicals by highly functional biomass. This book provides a comprehensive overview and in-depth technical research addressing recent progress in biomass conversion processes. It also covers studies on advanced techniques and methods for bioenergy and biofuel production