Enabling Reaction Selectivity of Platinum Catalysts by Photoinduced Electronic Effects

Reaction selectivity is crucial to producing target molecules of importance with minimum waste.This work reports an efficient and green strategy to improve reaction selectivity in visible-light-mediated chemical transformations by employing Pt/SiOx photocatalysts,which is ascribed to light-induced surface electronic modification in the small Pt nanocrystals.This strategy has been successfully applied to synthesize commercially valuable but thermodynamically unfavorable arylhydroxylamines with high selectivity via partial hydrogenation of the respective nitroarenes.Surface modification of the small Pt nanocrystals with triethanolamine(TEA)molecules further optimizes the Pt electronic structure to favor the reaction selectivity.The light-induced surface electronic structure alterations and the TEA chemical modification act synergistically to prevent the readsorption of desorbed electron-rich arylhydroxylamines.This prevents the complete hydrogenation of arylhydroxylamines to respective anilines,leading to high arylhydroxylamine selectivity of 81−91%.In addition,photoillumination of Pt nanocrystals always accelerates the reaction kinetics significantly regardless of their surface modification.

Global Classical Solutions to Partially Dissipative Quasilinear Hyperbolic Systems with One Weakly Linearly Degenerate Characteristic

For a kind of partially dissipative quasilinear hyperbolic systems without Shizuta-Kawashima condition,in which all the characteristics,except a weakly linearly degenerate one,are involved in the dissipation,the global existence of H 2 classical solution to the Cauchy problem with small initial data is obtained.

Asymptotic Stability of Equilibrium State to the Mixed Initial-Boundary Value Problem for Quasilinear Hyperbolic Systems

Under the internal dissipative condition, the Cauchy problem for inhomogeneous quasilinear hyperbolic systems with small initial data admits a unique global C1 solution, which exponentially decays to zero as t → +∞, while if the coefficient matrixΘ of boundary conditions satisfies the boundary dissipative condition, the mixed initialboundary value problem with small initial data for quasilinear hyperbolic systems with nonlinear terms of at least second order admits a unique global C1 solution, which also exponentially decays to zero as t → +∞. In this paper, under more general conditions, the authors investigate the combined effect of the internal dissipative condition and the boundary dissipative condition, and prove the global existence and exponential decay of the C1 solution to the mixed initial-boundary value problem for quasilinear hyperbolic systems with small initial data. This stability result is applied to a kind of models, and an example is given to show the possible exponential instability if the corresponding conditions are not satisfied.

Global Exact Boundary Controllability for General First-Order Quasilinear Hyperbolic Systems

For general first-order quasilinear hyperbolic systems,based on the analysis of simple wave solutions along characteristic trajectories,the global two-sided exact boundary controllability is achieved in a relatively short controlling time.