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The communication describes a general Paternò‐Büchi reaction under mild conditions, which is featured with visible light‐mediation, catalyst‐free and a broad range of substrates comparing with other strategies. Having overcome the synthetic limitations the PB reaction faces, this practical protocol can be employed to prepare a variety of multisubstituted oxetanes that often appear serving as important scaffolds in natural products and drugs. The common white light, the sole driving force in this case, can directly excite the carbonyl compounds to reach its triplet state, which then attacks an alkenes to generate a diradical intermediate, resulting in the oxetanes in high diastereoselectivity.

Green organic synthesis mediated by visible-light chemistry is highly desired in the academia and industry. Aqueous phase is undoubtedly the most environmentally friendly medium. We report herein a mild and...

Flow-induced vibration and noise widely exist in turbomachines and the connecting piping systems. The combined numerical method of computational fluid dynamics, computational structural dynamics, and computational vibroacoustics is employed to investigate the vibration and noise induced by the unsteady flow in the centrifugal compressor and pipes.Computational results indicate that the strongest pressure fluctuation is located on the clearance between the impeller and the stationary units due to the periodic rotor-stator interaction. However, the intense vibration occurs on the inlet and outlet pipes of the centrifugal compressor. Moreover, the computational result of the normal active acoustic intensity shows that the primary vibro-noise source is located on the outlet pipe. The computational result also clarifies that the thickness of the outlet pipe is one of the key parameters affecting the acoustic power output of the centrifugal compressor.