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The extraordinary performances of phase-coexisting ferroelectrics are significantly affected by not only the phase constitution but also the motion of domain walls. The study on the role of phase coexistence in the formation of ferroelectric and ferroelastic domain microstructures is of great importance to explain the enhanced piezoelectric properties. In situ high-energy diffraction and the Rayleigh law are utilized to reveal the interplay of phase constitution and domain configuration to the macroscopic electromechanical coupling effect in the morphotropic phase boundary composition of 0.365BiScO 3 –0.635PbTiO 3 during the application of a weak electrical loading in the present study. It was found that anisotropic phase transition and domain switching occur in polycrystalline ferroelectric ceramics and a phase transition occurs dramatically beyond the coercive field. Taking into account the important role of coupled ferroelectric and ferroelastic domain microstructures, we conceived a configuration of monoclinic domains coexisting with and bridging the tetragonal domains. The existence of bridging domains would provide an insight into the interplay of the phase and domain and explains the piezoelectric performance in the vicinity of morphotropic phase boundaries. 

The RSSH + H 2 S → RSH + HSSH reaction has been suggested by numerous labs to be important in H 2 S-mediated biological processes. Seven different mechanisms for this reaction (R = CH 3 , as a model) have been studied using the DFT methods (M06-2X and ωB97X-D) with the Dunning aug-cc-pV(T+d)Z basis sets. The reaction of CH 3 SSH with gas phase H 2 S has a very high energy barrier (>45 kcal mol −1 ), consistent with the available experimental observations. A series of substitution reactions R 1 –S–S–H + − S–R 2 (R 1 = Me, t Bu, Ad, R 2 = H, S–Me, S– t Bu, S–Ad) have been studied. The regioselectivity is largely affected by the steric bulkiness of R 1 , but is much less sensitive to R 2 . Thus, when R 1 is Me, all − S–R 2 favorably attack the internal S atom, leading to R 1 –S–S–R 2 . While for R 1 = t Bu, Ad, all − S–R 2 significantly prefer to attack the external S atom to form − S–S–R 2 . These results are in good agreement with the experimental observations.