A highly efficient di-C-glycosyltransferase GgCGT was discovered from the medicinal plant Glycyrrhiza glabra. GgCGT catalyzes a two-step di-C-glycosylation of flopropione-containing substrates with conversion rates of >98%. To elucidate the catalytic mechanisms of GgCGT, we solved its crystal structures in complex with UDP-Glc, UDP-Gal, UDP/phloretin, and UDP/nothofagin, respectively. Structural analysis revealed that the sugar donor selectivity was controlled by the hydrogen-bond interactions of sugar hydroxyl groups with D390 and other key residues. The di-C-glycosylation capability of GgCGT was attributed to a spacious substrate-binding tunnel, and the G389K mutation could switch di- to mono-C-glycosylation. GgCGT is the first di-C-glycosyltransferase with a crystal structure, and the first C-glycosyltransferase with a complex structure containing a sugar acceptor. This work could benefit the development of efficient biocatalysts to synthesize C-glycosides with medicinal potential.

This paper reports an ytterbium-doped linear-cavity fiber laser with the optical length of 1.6 km passively modelocked by a high modulation depth semiconductor saturable absorber mirror (SESAM). An ultra-low repetition rate of 191 kHz was achieved. The laser delivered the highly-chirped output pulses with the energy up to 75.2 nJ.Intensity, a.u. Pulse spectrum of 400-m mode-locked ytterbium-doped fiber laser where the central wavelength was 1033 nm and FWHM is 3.5 nm

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Ripe green banana (Musa sp., AAA group, cv. Zhonggang) fruits treated with 1-methylcyclopropene (1-MCP) significantly delayed the peaks of respiration rate and ethylene production but did not reduce the peak height. Mature banana fruits were also treated with 1-MCP for 24 h at 20 C and then exposed to 50 mL/L ethylene or stored at different temperatures to analyse the effects of external added ethylene. Reductions in firmness, titratable acidity (TA) and starch content (SC) of banana fruits were remarkably delayed by 1-MCP treatment. 1-MCP treatment also delayed the increase of total soluble sugar (TSS) and soluble pectin (SP) contents. Soluble solids (SS) content in the 1-MCP-treated fruit remained almost unchanged during the first 10 days of storage at 20 C. No significant differences in TA, TSS, SP and SS levels were observed between the fruit treated with 1-MCP alone and the fruit treated with 1-MCP plus ethylene. The 1-MCP effects on all the parameters related to banana ripening were enhanced by low temperature storage and reduced by high temperature storage.

We investigated the quantitative effect of internal shear on grain breakage during rock avalanche runout, by means of 38 ring‐shear experiments on identical sand samples at different normal stresses, shear strains and shear strain rates. We compared sample grain‐size characteristics before and after shearing. We found that grain size decreased with increase in normal stress and shear strain. Reduction in grain size was inferred to occur through grain breakage associated with grain interactions in strong force chains during strain. The results were consistent with observations of both inverse‐grading structure in deep rock avalanche exposures, and fining and grading of particles with increasing rock avalanche travel distance. Our study suggested that with appropriate calibration, variations in grain‐size distributions within a rock avalanche deposit would provide quantitative information on the distribution of internal shear during its runout.

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We have investigated the distributions of stellar azimuthal and radial velocity components V Φ and V R in the vertical position-velocity plane Z-V Z across the Galactic disc of 6.34 R 12.34 kpc and |Φ| 7.5 • using a Gaia and Gaia-LAMOST sample of stars. As found in previous works, the distributions exhibit significant spiral patterns. The V R distributions also show clear quadrupole patterns, which are the consequence of the well-known tilt of the velocity ellipsoid. The observed spiral and quadrupole patterns in the phase space plane vary strongly with radial and azimuthal positions. The phase spirals of V Φ become more and more relaxed as R increases. The spiral patterns of V Φ and V R and the quadrupole patterns of V R are strongest at −2 • < Φ < 2 • but negligible at 4 • < Φ < 6 • and −6 • < Φ < −4 • . Our results suggest an external origin of the phase spirals. In this scenario, the intruder, most likely the previously well-known Sagittarius dwarf galaxy, passed through the Galactic plane in the direction towards either Galactic center or anti-center. The azimuthal variations of the phase spirals also help us constrain the passage duration of the intruder. A detailed model is required to reproduce the observed radial and azimuthal variations of the phase spirals of V Φ and V R .