Evaluation of the antioxidant property and effects in Caenorhabditis elegans of Xiangxi flavor vinegar,a Hunan local traditional vinegar

Xiangxi flavor vinegar（XV） is one of Hunan Province＇s traditional fermented vinegars.It is produced from herb,rice,and spring water with spontaneous liquid-state fermentation techniques.In this study,we investigated the antioxidant property of XV by analyzing its antioxidant compounds,its free radical scavenging property in vitro and in vivo,and its effects on antioxidant enzyme activity and apoptosis in Caenorhabditis elegans.The results showed that XV is rich in antioxidants.In particular,ligustrazine reached 6.431 μg/ml.The in vitro 2,2-diphenyl-1-picrylhydrazyl free radical（DPPH＊）,hydroxyl radical（＊OH）,and superoxide anion radical（O2^（＊-）） scavenging rates of XV were 95.85%,97.22%,and 63.33%,respectively.The reactive oxygen species（ROS） content in XV-treated C.elegans decreased significantly（P0.01） compared to the control group.Giutathione peroxidase（GSH-Px）,superoxide dismutase（SOD）,and catalase（CAT） activities were remarkably increased（P0.01） in C.elegans after XV treatment.In addition,XV could upreguiate CED-9 protein expression and downreguiate CED-3 protein expression in C.elegans.These results prove that XV is rich in antioxidants and scavenges radicals in vitro efficiently.XV inhibits apoptosis in C.elegans probably by scavenging ROS and increasing the activities of its antioxidant enzymes.

Effect of substitution of Si by Al on the microstructure and mechanical properties of bainitic transformation-induced plasticity steels

The effect of partial or full substitution of Si by Al on the microstructure and mechanical properties has been extensively studied in multi-phase transformation-induced plasticity（TRIP） steels with polygonal ferrite matrix, but rarely studied in bainitic TRIP steels. The aim of the present study is to properly investigate the effect of Al and Si on bainite transformation, microstructure and mechanical properties in bainitic steels in order to provide guidelines for the alloying design as a function of process parameters for the 3 rd generation advanced high strength steels（AHSS）. It is shown from the dilatometry study,microstructural investigations and tensile properties measurements that the Al addition results in an acceleration whereas Si addition leads to a retardation in bainite transformation kinetics. The addition of Al retards the decomposition of austenite into pearlite and carbides at holding temperatures higher than450℃ whereas Si retards the decomposition of austenite into carbides at temperatures lower than 450℃.Consequently, the Al-added bainitic steel has a better strength-elongation combination at bainitic holding temperatures higher than 450℃ while Si-added steel has a better strength-elongation combination at temperatures lower than 450℃. The higher yield strength of Al-added steel is mainly attributed to its finer bainitic lath. The higher tensile strength of Si-added steel is not only related to the stronger contribution of Si on work hardening during deformation, but also due to the higher volume fraction of martensite or martensite/austenite（MA） blocks in all heat treatment conditions, as well as the lower mechanical stability of retained austenite in this steel.

Effect of Solution Annealing on Microstructure and Mechanical Properties of a Ni-Cr-W-Fe Alloy

The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700？C ultra-supercritical power plants was investigated. Test samples in this study were subjected to different solution treatments and the same aging treatment（at 760？C for 1 h）.When solution annealing temperature was elevated from 1020？C to 1150？C, the stress-rupture life at750？C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from12% to 17%, and the elongation of the tensile at 750？C was improved from 11% to 24%. All tensile and stress-rupture samples displayed an intergranular dimple mixed fracture. Intergranular micro-cracks had a great relationship with the morphology of grain boundary carbides. Most carbides retained the morphology of globular shape and continuous thin plate. After tensile and stress-rupture tests, a few carbides were converted into lamellar. The results showed that intergranular micro-cracks were easier to form at continuous thin plate carbides than at globular shape carbides. Lamellar carbides hardly caused the nucleation of micro-cracks. Besides, grain boundaries sliding and elements diffusion during stressrupture tests led to the formation of precipitate free zones, which accelerated the extension of microcracks and influenced the stress-rupture life.

Simultaneous Improvements of Thermal Stability and Mechanical Properties of Poly(propylene carbonate) via Incorporation of Environmental-friendly Polydopamine

Inspired by the photoprotection, radical scavenging of melanin together with versatile adhesive ability of mussel proteins, polydopamine（PDA） nanoparticles were successfully prepared and incorporated into environmentally friendly polymer, poly（propylene carbonate）（PPC） via solvent blending. The prepared composites exhibited excellent thermal stability in air and nitrogen atmosphere and extraordinary mechanical properties. The composites displayed eminent increase of temperature at 5% weight loss（T5%） by 30-100 K with 0.3 wt%-2.0 wt% loadings, meanwhile, the tensile strength and Young＇s modulus were significantly improved from 11.5 MPa and 553.7 MPa to 40.5 MPa and 2411.2 MPa, respectively. The kinetic calculation indicated that improvement of T5% is presumably derived from suppressing chain-end unzipping. The glass transition temperature（Tg） of the PPC/PDA composites increased by 8-10 K. This is probably due to hydrogen bonding interaction since the abundant proton donors along PDA chains would interact with proton acceptors like C = O and C―O―C in PPC which would cause restriction of segmental motion of PPC chains.