This study is the first attempt to investigate the characteristics of the drop size distribution (DSD) and drop shape relation (DSR) of seven typhoons after making landfall in China. Four typhoons were sampled by a C-band polarimetric radar (CPOL) and a two-dimensional video disdrometer (2DVD) in Jiangsu Province (East China) while three typhoons were sampled by two 2DVDs in Guangdong Province (south China). Although the DSD and DSR are different in individual typhoons, the computed DSD parameters in these two groups of typhoons possess similar characteristics. The DSR is more spherical, and the shape-slope (μ-Λ) relation has a significantly lower value of μ for a given Λ than that in typhoons in the Taiwan area, indicating different microphysical processes of typhoons between continental China and other regions (western Pacific and Atlantic). The convective precipitation of typhoons contains higher raindrop concentration and lower raindrop diameter than that of the maritime convection. A Z (reflectivity factor)-R (rain rate) relationship, Z = 147.28R 1.38 , is derived for typhoons over land in China. The contoured frequency by altitude diagrams of CPOL polarimeteric parameters and the vertical distributions of hydrometeors and retrieved DSD parameters are further investigated to better reveal the microphysical processes of two typhoons (Matmo and Soudelor). Despite the differences in DSDs and polarimetric parameters, microphysical characteristics in both typhoons are similar. The CPOL-derived microphysical properties, in conjunction with high freezing level, suggest that warm rain accretion processes dominate typhoon rainfall after landfall in China.In addition to the characteristics of the DSDs, the shapes of the raindrops (axis ratio) also vary a lot with different weather systems because of the oscillation and canting effect of raindrops (e.g., Gorgucci et al., 2000). Polarimetric radars make use of this axis ratio to measure the difference in backscatter reflectivity and the propagation phase (Thurai & Bringi, 2005). Drop shapes therefore play a crucial role in retrieving the DSD of the raindrops and the subsequent estimation of rainfall rates from the polarimetric radar measurements (e.g., Gorgucci et al., 2000). A small error in the axis ratio can lead to significant errors in the estimated DSD and rainfall rates (Bringi & Chandrasekar, 2001).

Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl-type radicals (X-CCH-Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas-phase dissociation of cysteine sulfinyl radical (X-Cys SOC -Y) ions through homolysis of a C a À C b bond. This fragmentation produces a glycyl-type radical upon losing CH 2 SO, and the degree of this loss is closely tied to the stability of the as-formed radical. Theoretical calculations indicate that the energy of the C a ÀC b bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates.

Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl-type radicals (X-(.) CH-Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas-phase dissociation of cysteine sulfinyl radical (X-Cys SO .-Y) ions through homolysis of a Cα Cβ bond. This fragmentation produces a glycyl-type radical upon losing CH2 SO, and the degree of this loss is closely tied to the stability of the as-formed radical. Theoretical calculations indicate that the energy of the Cα Cβ bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates.

The sulfide oxygenation activities of both heptamolybdate ([Mo7O24]6-, [1]6-) and its peroxo adduct [Mo7O22(O2)2]6- ([2]6-) were examined in this contribution. [Mo7O22(O2)2]6- was prepared in a yield of 65% from (NH4)6[Mo7O24] (1a) upon treatment of 10 equiv. of H2O2 and structurally identified through single crystal X-ray diffraction study. (nBu4N)6[Mo7O22(O2)2] (2b) is an efficient catalyst for the sequential oxygenation of methyl phenyl sulfide (MPS) by H2O2 to the corresponding sulfoxide and subsequently sulfone with a 100% utility of H2O2. Surprisingly, (nBu4N)6[Mo7O24] (1b) is a significantly faster catalyst than 2b for MPS oxygenation under identical conditions. The pseudo-first order kcat constants from initial rate kinetics are 54 M-1 s-1 and 19 M-1 s-1 for 1b and 2b, respectively. Electrospray ionization mass spectrometry (ESI-MS) investigation of 1b under the catalytic reaction conditions revealed that [Mo2O11]2- is likely the main active species in sulfide oxygenation by H2O2.