ABSTRACT
Ceria-based compounds with additions of La and F (CLF compounds) were prepared by using industrial-grade fluorinated lanthanum cerium carbonate as a precursor via a facile calcination method. The evolution of phase structures of the compounds during preparation and the relationship between the structure and the polishing performance were investigated. The compounds consist of three phases: CeO2, LaOF, and LaF3. The phase component could be controlled by tuning the calcination process. A higher degree of fluorination and a higher calcination temperature led to the formation of more LaOF and less LaF3 phases. The LaOF phase performs a higher stock removal rate. The best polishing efficiency was achieved with LaOF phase ratio around 18%. Intermetallic LaF3 is a low-hardness phase and is easily crushed during polishing, which lowers the removal rate and shortens the useful life of the polishing powder.
ABSTRACT
It was disclosed in our group for the first time that the flavonoids in Lonicera japonica Thunb. are related to its therapy for gastric ulcer. Based on this finding, 20 flavonoids were selected for Helicobacter pylori urease inhibitory activity evaluation, and quercetin showed excellent potency with IC(50) of 11.2 ± 0.9 µM. Structure-activity relationship analysis revealed that removal of the 5-, 3-, or 3'-OH in quercetin led to a sharp decrease in activity. Thus, 3- and 5-OH as well as 3',4'-dihydroxyl groups are believed to be the key structural characteristics for active compounds, which was supported by the molecular docking study. Meanwhile, the results obtained from molecular docking and enzymatic kinetics research strongly suggested that quercetin is a noncompetitive urease inhibitor, indicating that quercetin may be able to tolerate extensive structural modification irrespective of the shape of the active site cavity and could be used as a lead candidate for the development of novel urease inhibitors.
