2,4-Dichloro-7-fluoro­quinazoline

The mol­ecule of the title compound, C8H3Cl2FN2, is essentially planar, with a maximum deviation of 0.018 (2) Å. In the crystal, π–π stacking is observed between parallel quinazoline moieties of adjacent mol­ecules, the centroid–centroid distance being 3.8476 (14) Å

A “Double-Multi” Model for Electromigration of Lithiums and Chlorides in ASR Affected Concrete

Existing reinforced concrete structures experience severe durability degradation when subjected to alkali– silica reaction (ASR) and chloride attack. A special electrochemical rehabilitation treatment, containing lithium compound anolyte, has been developed to drive lithium ions into concrete as well as remove chlorides simultaneously, for mitigating both the ASR-induced cracks and the chloride-induced corrosion. Good performance of introduced lithiums in controlling ASR-induced expansion has already been proved. Unfortunately, the migration mechanism of lithium in concrete under an external electric field is seldom investigated in existing literature. In this study, with help of the “double-multi” model, the efficiency of impregnation of lithium ions and simultaneously the removal of chloride ions through a specific electrochemical treatment are numerically evaluated, which results into the distribution profiles of all typical ionic species. The heterogeneous concrete model examines the aggregate effect, especially on the interaction with lithiums which are supposed to mitigate ASR. The ionic interaction between different species and the electrochemical reaction at electrodes are also considered. Through a relative thorough modelling of multi-phase and multi-species, a systemic parametric analysis based on a series of significant factors during electrochemical treatment (e.g., current density, treatment time, temperature, cathode position and concentration of lithium solution) reveals some important tendencies of ionic electromigration in concrete, which are supposed to guide the field application

Effect of prescribed temperature on mixed convection boundary layer in the unsteady stagnation point flow toward a stretching vertical sheet

The solution to the unsteady mixed convection boundary layer flow and heat transfer problem due to a stretching vertical surface is presented in this paper. The unsteadiness in the flow and temperature fields is caused by the time-dependent of the stretching velocity and the surface temperature. The effects of the unsteadiness parameter, buoyancy parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. It is observed that the solutions exist for all values of buoyancy parameter. Comparison with known results for steady-state flow is excellent

(11-Methyl­pyrido[2,3-b][1,4]benzo­diazepin-6-yl)(phen­yl)methanone

In the title compound, C20H15N3O, the diazepine ring adopts a boat conformation. The dihedral angle between pyridine and benzene rings is 55.2 (1)°. The benzoyl phenyl ring forms dihedral angles of 49.4 (1) and 75.9 (1)°, respectively, with the pyridine and benzene rings. In the crystal, mol­ecules are linked into centrosymmetric dimers by pairs of C—H⋯N hydrogen bonds