Effects of Ethanol Condensation Reflux Extraction and Ultrasound-assisted Extraction on the Content of Total Flavonoids of Pueraria edulis

With Pueraria edulis from different habitats in Yunnan Province,Guangdong Province and Guangxi Zhuang autonomous region as materials,the medicinal materials of P.edulis were extracted by ethanol condensation reflux extraction and ultrasound-assisted extraction,and the effects of different extraction methods the contents of total flavonoids in P.edulis from different areas were compared.The results showed that the best extraction time for P.edulis in Yunnan Province was 20 min,and that for Guangdong and Guangxi Zhuang Autonomous Region was 30 min.The yield of total flavonoids from P.edulis extracted by the condensation reflux extraction method was relatively better.The content of total flavonoids in P.edulis in Yunnan was the highest with an average content of 0.2557%,while the average content of total flavonoids in P.edulis in Guangdong was the lowest with an average content of 0.2108%.

Numerical Simulations on Countercurrent Gas-Liquid Flow in a PWR Hot Leg with Air-Water Flow in a 1/15th Scale-Model

To clarify the countercurrent flow in a PWR hot leg under reflux condensation, numerical simulations of countercurrent air-water flow for a 1/15th scale model of the PWR hot leg were conducted using the two-fluid model implemented in CFD software. In this paper, the effect of expansion of the inclined pipe, which is the actual plant geometry, was evaluated. When increasing the air velocity, CCFL characteristics and the mechanism of flow pattern transition had significant differences between the case with and without expansion of the inclined pipe. CCFL characteristics were mitigated in the case with expansion. The effect of computational grid size was also discussed. When the supplied water velocity was small, the predicted flow pattern transition point agreed well with the measured data by increasing the number of cells. On the other hand, when the air velocity was decreasing, there were no significant differences in each case.

Numerical Simulation of Countercurrent Flow in a PWR Hot Leg by Using Two-Fluid Model

In order to evaluate CCFL （countercurrent flow limitation） characteristics in a PWR （pressurized water reactor） hot leg under reflux condensation, numerical simulations have been conducted using a 2F （two-fluid） model and a VOF （volume of fluid） method implemented in the CFD （computational fluid dynamics） software, FLUENT6.3.26. The 2F model gave good agreement with CCFL data in low pressure conditions but did not give good results for high pressure steam-water conditions. In the previous study, the computational grid and schemes were improved in the VOF method to improve calculations in circular tubes, and the calculated CCFL characteristics agreed well with the UPTF （Upper Plenum Test Facility） data at 1.5 MPa. In this study, therefore, using the 2F model and the computational grid previously improved for the VOF calculations, numerical simulations were conducted for steam-water flows at 1.5 MPa under PWR full-scale conditions. In the range of medium gas volumetric fluxes, the calculated CCFL characteristics agreed well with the values calculated by the VOF method and the UPTF data at 1.5 MPa. This indicated that the reference set of the interfacial drag correlations employed in this study could be applied not only to low pressures but also to high pressures.

A two-step approach to synthesis of Co（OH）2/γ-NiOOH/ reduced graphene oxide nanocomposite for high performance supercapacitors

A two-step approach was reported to fabricate cobaltous hydroxide/y- nickel oxide hydroxide/reduced graphene oxide （Co（OH）217-NiOOHIRGO） nanocompo- sites on nickel foam by combining the reduction of graphene oxide with the help of refux condensation and the subsequent hydrothermal of Co（OH）2 on RGO. The microstructural, surface morphology and electrochemical properties of the Co（OH）2/γ-NiOOH/RGO nanocomposite were investigated. The results showed that the surface of the first-step fabricated γ-NiOOH/RGO nanocomposites was uniformly coated by Co（OH）2 nanoflakes with lateral size of tens of nm and thickness of several nm. Co（OH）2/γ-NiOOHIRGO nanocomposite demonstrated a high specific capacitance （745 mF/cm= at 0.5 mAJcm2） and a cycling stability of 69.8% after 1000 cycles at 30 mV/cm2· γ-NiOOH/RGO//Co（OH）2/γ- NiOOH/RGO asymmetric supercapacitor was assembled, and maximum gravimetric energy density of 57.3 W.h/kg and power density of 66.1 kW/kg were achieved. The synergistic effect between the highly conductive graphene and the nanoflake Co（OH）2 structure was responsible for the high electrochemical performance of the hybrid electrode. It is expected that this research could offer a simple method to prepare graphene-based electrode materials.