Melt flow,solidification structures,and defects in 316 L steel strips produced by vertical centrifugal casting

Vertical centrifugal casting can significantly enhance the filling capability of molten metals,enabling the production of complex thin-walled castings at near-rapid cooling rates.In this study,the melt flow,solidification structures,and defects in 316 L steel cast strips with a geometry of 80 mm×60 mm×2.5 mm produced by vertical centrifugal casting were numerically and experimentally analyzed under different rotation speeds.With gradually increasing the rotation speed from 150 r/min to 900 r/min,the simulated results showed the shortest filling time and minimum porosity volume in the cast strip at a rotation speed of 600 r/min.Since a strong turbulent flow was generated by the rotation of the mold cavity during the filling process,experimental results showed that a“non-dendritic”structure was obtained in 316 L cast strip when centrifugal force was involved,whereas the typical dendritic structure was observed in the reference sample without rotation.Most areas of the cast strip exhibited one-dimensional cooling,but three-sided cooling appeared near the side of the cast strip.Moreover,the pores and cracks in the 316 L strips were detected by computed tomography scanning and analyzed with the corresponding numerical simulations.Results indicated the existence of an optimal rotational speed for producing cast strips with minimal casting defects.This study provides a better understanding of the filling and solidification processes of strips produced by vertical centrifugal casting.

Regulation of oxidative stress inside living cells through polythiophene derivatives

Oxidative stress stimulated by angiotensin II（Ang II） plays an important role in the progression of inflammation and cardiovascular disease. In this work, polythiophene modified with dihydropyridine groups（PTDHP） realized the control of oxidative stress induced by Angiotensin II stimulation in living cells, by inhibiting the activity of NADPH oxidase via DHP groups. Upon light irradiation, the PTDHP could sensitize surrounding oxygen molecules to generate reactive oxygen species（ROS）. The generated ROS oxidized the pendant DHP of polythiophene into pyridine group, which inactivated the control ability of DHP to oxidative stress in living cells. Thus, PTDHP can not only control the intracellular oxidative stress effectively and suppress ROS to some degree in dark, but also regulate its anti-oxidative effect under light irradiation.

A new kind of neutrino transformation was found by Daya Bay neutrino experiment

At 14：00 Beijing time of March 8, 2012, Professor Yifang Wang, the spokesperson of InternationM Collaboration of Daya Bay neutrino experiment, declared in Beijing that a new kind of neutrino transformation was found dur- ing Daya Bay neutrino experiment （see Fig. 1）. Also, the transformation probability hereof was measured. The re- sult showed that sin2（2013） was 9.2%, and the error was 1.7%. Also, as over 5 times per the standard deviation, it was determined that sin2（2013） was not zero.