[Analysis of chemical constituents in ethyl acetate extract of Taxilli Herba by UPLC-Q-Exactive-MS and screening of potential xanthine oxidase inhibitors].

The present study analyzed and identified the chemical constituents from ethyl acetate(EA) extract of Taxilli Herba with UPLC-Q-Exactive-MS and screened active xanthine oxidase(XO) inhibitors with HPLC. The analysis was performed on an Hypersil GOLD C_(18) reversed-phase column(2.1 mm×50 mm, 1.9 µm), with the mobile phase of water containing 1% formic acid(A) and methanol(B) under gradient elution, the flow rate of 0.3 mL·min~(-1), and the injection volume of 5 µL. ESI source was used for MS and the compounds were collected in positive and negative ion modes. Xcalibur 4.1 was used to analyze the retention time, accurate relative molecular weight, and fragmentation of the compounds. The inhibitory activity of some known compounds on XO was screened by HPLC. Thirty chemical constituents were identified, including phenolic acids and flavonoids by experimental data combined with information of standards, data reported previously, and databases, such as MzCloud and ChemSpider. The activities of 10 chemical components were screened. Gallic acid and naringenin chalcone had strong inhibitory activities on XO with IC_(50) of 57 µg·mL~(-1) and 108 µg·mL~(-1). UPLC-Q-Exactive-MS allows the accurate, rapid, and comprehensive identification of main chemical constituents from Taxilli Herba. Gallic acid and naringenin chalcone may be the active components of XO inhibitors.

Numerical Study on the Evaporation of a Non-Spherical Sessile Droplet.

To better understand the evaporation of a non-spherical droplet, a two-dimensional simulation was conducted to investigate the evaporation on the asymmetric cross-section of non-spherical sessile droplets, which are characterized by two curvatures with two different contact angles on both sides. The temperature distribution, internal flow, and evaporation flux distribution at a quasi-steady state were revealed to be different from the spherical droplets. When heated from the substrate, the lowest surface temperature moves to the side of higher curvature or larger contact angle, forming a single vortex in the droplet. This single-vortex formation continues to be enhanced by enlarging the contact angle discrepancy. Unlike spherical droplets, the smaller curvature side of a non-spherical sessile droplet will release more evaporation flux. In addition, it is found that the non-spherical sessile droplets could surpass the spherical sessile droplets in evaporation flux.