Antioxidant activity of longan (Dimocarpus longan) barks and leaves

In this paper, the barks and leaves of longan (Dimocarpus longan Lour.) were extracted with 80% methanol. The antioxidant activity and the contents of ellagic acid (EA) in the extracts were investigated. For the evaluation of antioxidant activities, the extracts possess almost the same 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. Besides, the antioxidant activity was concomitant with the development of the reducing power with high correlation coefficients. The contents of EA in the extracts were 0.91 and 3.723 mg/g dry samples, respectively. After hydrolysis, the EA contents increased almost three and four times. Therefore, the ellagic acid in longan barks and leaves exist mostly in the form of ellagitannins. The research showed that longan barks and leaves not only were excellent sources of free-radical inhibitors, but also had potential use in the production of ellagic acid.Key words: Antioxidant activity, ellagic acid, longan, barks, leaves

Multiphase flow numerical simulation of ladle bottom powder injection

Numerical simulations were performed on bottom injection of calcium oxide particles through double nozzle porous bricks into a 300 t hot metal ladle. The distribution characteristics of the calcium oxide particles in the ladle were predicted and analyzed. The modeling results show that, when the bottom blown porous bricks are located symmetrically off-centre by 1 / 2 ladle bottom radius and the injection speed of the calcium oxide particles is 7 m / s, an optimum distribution of the calcium oxide particles in the hot metal bath in the ladle can be achieved. This will provide a reference for evaluating the feasibility of applying bottom injection of the calcium oxide powder into hot metal ladles for desulfurization in the actual production process