COSMO‐RS Calculations of Partition Coefficients: Different Tools for Conformation Search

This work is encouraged by the growing interest and recent success of quantum mechanics‐based methods in modeling of thermodynamic properties in the field of chemical engineering and life sciences. Among those, the COSMO‐RS model has become one of the most popular methods to predict phase equilibria in complex bio‐related systems. Recently, we have shown that the quality of predictions of n‐octanol/water and micelle/water partition coefficients is improved when the weighted mixtures of conformers are used to represent molecules, thereby demanding that the conformation analysis is performed for each component of the system. In this paper, different methods for performing the conformational search are evaluated. Micelle/water partition coefficients of solutes from different homologous series in aqueous solutions of Triton X100 as well as the n‐octanol/water partitioning of three common drugs (aminopinicillanic acid, ampicillin, and penicillin G) are calculated and compared with experimental data. Conformational analysis is made by the HyperChem program for the molecules placed in vacuum as well as by using the molecular dynamics simulation in a solvent medium (n‐octanol and water). It is demonstrated that molecular dynamics simulation is a promising tool to conduct conformational analysis. Along with the possibility of providing the conformers for large surfactant and pharmaceutical molecules, the method accounts for the solvent in a realistic manner. The results for micelle/water partition coefficients illustrate that n‐octanol is a reasonable approximation for the “micelle‐like” medium in molecular dynamics (MD) simulations. Predicted n‐octanol/water partition coefficients of three penicillins are in a good agreement with literature data and values calculated by a common quantitative structure‐activity relationship (QSAR).     

Mastering the production of 08GDNFL steel fitting castings

Chemical and Petroleum Engineering -     

Water purification with a high-gradient magnetic filter

Textile Scientific-Research Institute. I. V. Kurchatov Institute of Atomic Energy. Translated from Atomnaya Énergiya, Vol. 70, No. 6, pp. 412–413, June, 1991.     

Hormonal regulation of anabolic processes and the rate of protein utilization in the early postnatal period

The levels of thyroid, pituitary and corticosteroid hormones--thyroxine, triiodthyronine, 11-oxicorticosteroids in blood serum, somatotropin in pituitary and processes of protein assimilation are studied in rats during early postnatal period. The highest endogen production of thyroxine, triiodthyronine and somatotropin is determined in 15 days old infant rats. The highest levels of protein utilization are determinated in 7-15 days old rats, then the process decreases with going over to definitive nutrition. Endogen production of anabolic hormones--thyroxine, triiodthyronine and somatotropin correlates to high levels of protein utilization in infant rats during the first days after birth.     

Experimental investigation of compact silicon carbide heat exchangers for high temperatures

The results of experimental investigations of novel ceramic high-temperature heat exchangers (HTHE) and its main characteristics such as effectiveness and power load as a function of mass flow and the geometry of the channels are presented. Firstly, some information on the background and the manufacturing of the HTHE, which is based on honey comb structures made out of extruded silicon carbide, is given. The experimental tests have been carried out with air as a heat transfer medium at temperatures of up to 1000 °C. The experimental set-up is described in detail. The acquired characteristic temperature and effectiveness data for different inlet temperatures and mass flows are discussed. They have been compared with data from theoretical calculations as well as with characteristic data of typical counter flow heat exchangers. Additionally, thermal shock tests have been carried out for a qualitative testing of the mechanical strength. Finally, a conclusion and an outlook on further activities are given.     

Synthesis,Structure, and Properties of Halloysite/Magnetite Composite

Protection of Metals and Physical Chemistry of Surfaces - Halloysite/magnetite composite was synthesized by chemical coprecipitation. To evaluate the crystal structure, texture, surface morphology,...     

The Development of a Method for the Production of Structural Polymeric Materials on the Basis of Norbornene Derivatives

Theoretical Foundations of Chemical Engineering - Process parameters of the polymerization of a mixture of exo,exo- and endo,endo-dimethyl esters of norbornene-2,3-dicarboxylic acid in the bulk of...