introduction: retreatment is performed in teeth with unsuccessful root canal therapy or persistent apical lesion. the most important factor for achieving successful retreatment is thorough cleaning and reshaping. niti files and rotary instruments are widely used for the removal of obturatants. this study compared the ability of mtwo and d-race retreatment systems to remove residual gutta-percha...

Neutron diffraction analysis was employed to measure residual stresses near welds in used anhydrous ammonia nurse tanks. Tensile residual stresses contribute to stress corrosion cracking of nurse tanks, which can cause tanks to release toxic ammonia vapor. The analysis showed that tensile residual stresses were present in the tanks measured, and the magnitudes of these stresses approached the y...

Due to low stiffness of braces after yielding, the structures with buckling-restrained braces (BRBs) experience high residual drifts during an earthquake, which can be intensified by aftershocks and causes considerable damages to structures. Also, due to poor distribution of stiffness, this problem is exacerbated for irregular structures. Recently, the yielding brace system (YBS) has been intro...