Behavior of Defective Curved Steel Beams Strengthened by a CFRP Composite

Mechanics of Composite Materials - The main purpose of this study is investigation of the effect of CFRP strengthening on the behavior of defective vertical curved steel beams with a square hollow...     

Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence

The dynamic 1H NMR study of some primary carbamates in the solvents CDCl3 and CD3COCD3 between 183 and 298 K is reported. The free energies of activation, thus obtained (12.4 to 14.3 kcal mol-1), were attributed to the conformational isomerization about the N-C bond. These barriers to rotation show solvent dependence in contrast to the tertiary analogues and are lower in free energy by ca. 2-3 kcal mol-1.     

Dynamic H NMR study of 4-methylphenoxyimidoyl azides: conformational or configurational isomerisation?

Dynamic ¹H NMR (500 MHz) investigation of 4-methylphenoxyimidoyl azides (4-CH₃-C₆H₄-O-CN-Y)-N₃, Y=4-CH₃-C₆H₄-SO₂-, 4-Br-C₆H₄-SO₂-, C₆H₅SO₂-, CH₃-SO₂-, -CN in acetone-d₆ at temperature range of 195-280 K is reported. The observed free energy barrier (almost 12 kcal mol⁻¹) is attributed to conformational isomerisation about the N-S bond for Y=4-CH₃-C₆H₄-SO₂-, 4-Br-C₆H₄-SO₂-, C₆H₅SO₂-, CH₃-SO₂- and (almost 14 kcal mol⁻¹) to configurational isomerisation (E/Z) about CN bond for Y=-CN.