Among the metal-based nanoparticles, silver nanoparticles catalysis has been of great interest in organic synthesis and has expanded rapidly in the past ten years because of nanosilver catalysts' unique reactivity and selectivity, stability, as well as recyclability in catalytic reactions. As can be seen from the research results reported in this critical review, the application of heterogeneous silver-based nanoparticles to general organic reactions has proved to be an effective strategy in the development of highly efficient organic transformations in term of efficiency and selectivity. In particular, this review revealed the powerful potential of nanosilver catalysis in total synthesis of natural products and pharmaceutical molecules.

We report the results of our systematic survey for Galactic 6.7 GHz Class II CH 3 OH maser emission toward a sample of young stellar objects. The survey was conducted with the Shanghai Tianma Radio Telescope (TMRT). The sample consists of 3348 sources selected from the all-sky Wide-Field Infrared Survey Explorer (WISE) point source catalog. We have discussed the selection criteria in detail and the detection results of those at high Galactic latitudes (i.e. |b| > 2 • ) in a previous paper (paper I). Here, we present the results from the survey of those at low Galactic latitudes, i.e. |b| < 2 • . Of 1875 selected WISE point sources, 291 positions that were actually associated with 224 sources were detected with CH 3 OH maser emission. Among them, 32 are newly detected. Majority of the newly detected sources are associated with bright WISE sources. The majority of the detected sources (209/224 = 93.3%) are quite close to the Galactic Plane (|b| < 1 • ) and lie on the inner spiral arms with positive LSR velocities. Detection rate and the color-color distribution of our detection are all matched with our anticipation. Combining with detections from previous surveys, we compile a catalogue of 1085 sources with 6.7 GHz CH 3 OH maser emission in our Galaxy.

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