Fusibility diagram of the BaAl2O4-Ba2SiO4-BaZrO3 system

Conclusions New types of cement were developed from the BaAl₂O₄-Ba₂SiO₄-BaZrO₃ system. The cements are characterized by high refractoriness (over 1800°C) and cold-crushing strength (up to 885 kgf/cm²) and a high content of BaO (up to 66%).A statistical method of extremum experiments was used to plot the fusibility diagram of this system. The analytically predicted data agree well with the measured quantities.Translated from Ogneupory, No. 3, pp. 48–50, March, 1978.     

The effect of different orientations in rigid rod polyimide films on the graphitized products

The effect of uniaxial and in-plane orientation of different rigid-rod homo- and co-polyimide films on the development of graphite structure after heat treatment up to 3070 K was investigated. The magnetoresistance and X-ray diffraction measurements were carried out to estimate the degree of graphitization and in-plane orientation of graphite crystallites. Both pristine and in-plane pre-oriented polyimide films show high degrees of graphitization. In-plane cold-drawing leads to the increase of in-plane orientation of polyimide films, but it produces the different actions on the graphitization parameters of homo- and co-polyimide films. While the cold pre-drawing of homo-polyimide films increases their graphitizability, this pre-treatment of the co-polyimide films does not lead to the improvement of graphitized material’s characteristics. The uniaxial orientation results in the hindrance of graphitization. The role of the supramolecular structure of ordered regions of polyimide films in the development of graphite structure under graphitization process has been discussed.     

Generalized diagrams and creep limits of dinas refractories for coke furnaces

Conclusions Creep in dinas refractories may be described in the framework of an elastoplastic model, facilitating the construction of generalized creep diagrams. With their aid we can obtain predictions of the values of long-term strength (creep limits) for dinas for periods of upto 12 years. It is shown that the creep limit of dinas after 15–25 years' service in coke ovens is 1.5–2.5 times higher than in the original refractories of contemporary production.Translated from Ogneupory, No. 5, pp. 16–21, May, 1989.     

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).