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2-phosphonobutane-1,2,4-tricarboxylic acid is(pbtc) a member of phosphonate family, and used as corrosion and scale inhibitor in cooling water systems. phosphonocarboxylates as a member of organophosphorus compounds have c-p and p-o bonds in their structures. pbtc is mainly used as carbonate scale inhibitor (caco3), sulphate scale inhibitor (caso4), corrosion inhibitor of low alloyed steel, eff...

introduction: obtaining top academic position among countries of the middle east and having advanced knowledge and ability to produce knowledge are among the most important goals set in iran’s twenty-year vision. present study aimed to determine impact factor of specialized and technical journals of iran and to compare with selected countries and provide appropriate recommendation. methods: in ...

in this work, different types of chaotic 1-manifolds which lie on the chaotic spheres or on a torus are introduced. some types of retractions of the chaotic spheres affect on the 1-chaotic systems, and other types of retractions occur to the geometric manifold but make the 1-chaotic manifold invariant. the existed retractions are discussed through new proved theorems. also we construct diffe...

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). the c2 symmetric twist-chair (2-tc)conformation of 2 is calculated to be 7.4 kj...