No abstract

Curcuminoids are functional secondary metabolites abundant in turmeric. In the present study, a simple and efficient method for enrichment of curcuminoids from turmeric was developed using macroporous resin. Eight different types of macroporous resins were examined by static adsorption/desorption properties and the type of XDA-7 was selected as the optimum one. Under the optimized conditions, the final contents of refined extract excluded 84.2% of impurities, by comparison with crude extract in a scale-up experiment. Meanwhile, 8 representative curcuminoids including 4 dihydro- and tetrahydro-curcuminoids were enriched, isolated, and identified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) data. In addition, the individual curcuminoids were prepared to evaluate their cytotoxic activity toward HeLa tumor cell lines. All compounds, especially the trace amount of curcuminoids, demonstrated notable cytotoxic activity. The results supported that those trace amount of curcuminoids can be good candidates for drug development as anticancer agents. The purification process was simple and efficient, which could afford a potential method to enrich and concentrate not only the major curcuminoids, but also the trace amount of ones from turmeric raw materials for industrial applications.

No abstract

The friction contact boundary between the tool flank of the milling cutter and the machining transition surface is important indicator to reveal the third deformation zone tool contact relationship and assessing the frictional wear performance of milling cutter. The existing models for friction boundary identification pay attention to the maximum width of accumulated friction and wear on the tool flank, ignoring the variability of the overall and local morphology of the friction boundary on the flank. Aimed at the influence of milling vibration on the instantaneous position of the cutter teeth and the machining transition surface, the solution and discrimination for the instantaneous position vector on the flank was proposed. Based on the mutagenicity of the instantaneous temperature and stress distribution, the influence of the instantaneous contact, extrusion and deformation between the tool flank and the machined transition surface on the friction area was recognized. The calculation model of friction boundary of the flank was established. The irregularities of the distributions of the friction boundaries of the tool flank were revealed. The fractal recognition methods for instantaneous and cumulative friction boundary of the flank were proposed. And response was studied and verified with experiments. The results showed that it could effectively identify the irregular distribution of the friction boundary on the flank with the use of the above models. The formation and evolution of the friction boundary on the tool flank of the high-energy-efficiency milling cutters were revealed.

No abstract