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Abstract: Disordered Fe(Al) solid solution powders with nano-grain size were fabricated by mechanical alloying, and subsequently the milled powders were consolidated by plasma activated sintering (PAS) and hot pressing (HP), respectively. The effect of the two fabrication methods on microstructure and mechanical properties of Fe3Al was investigated. Disordered Fe3Al with submicron-grain size was obtained by PAS, while ordered Fe3Al with micron-grain size was obtained by HP. Compared with ordered Fe3Al with micron-grain size by HP, disordered Fe3Al with submicron-grain size by PAS had higher hardness and toughness. Fe3AlC0.5 was precipitated in all specimens with methanol addition during mechanic alloying. The precipitation of Fe3AlC0.5 improved the hardness of Fe3Al, but was harmful to the toughness of Fe3Al. [Copyright &y& Elsevier]

Abstract: This paper studies the effect of titanium concentration on the morphology of primary M7C3 carbides in hypereutectic high chromium white cast iron by means of the optical microscopy (OM), the scanning electron microscopy (SEM), the X-ray diffraction (XRD), the energy dispersive X-ray spectrometry (EDS) and Leica image analyzer. Theoretical calculation shows that solute Ti atoms can react with carbon and form TiC particles under certain conditions in the melt of hypereutectic high chromium cast iron. The experimental results show that the morphology of primary M7C3 carbides can be improved by adding a suitable amount of Ti. This improvement correlated with the emergence of TiC particles. These particles can act as the substrates for heterogeneous nucleation of primary M7C3 carbides, which results in significant refinement of the final grain size. [Copyright &y& Elsevier]

To construct an engineered Saccharomyces cerevisiae producing high titres of amorpha-4,11-diene, we investigated the possible synergistic effect of different vectors containing amorpha-4,11-diene synthase(ADS) gene within one yeast cell. We constructed the ADS recombinant plasmid pGADADS. This plasmid and another ADS recombinant plasmid pYeDP60/G/ADS were alone, or co-transformed into yeast Saccharomyces cerevisiae W303-1B and WK1, respectively, resulting in the following engineered yeasts, W303B[pGADADS], W303B[pYGADS], W303B[pYGADS+pGADADS], WK1[pGADADS], WK1[pYGADS] and WK1[pYGADS+pGADADS]. All of the six strains were cultured for GC-MS analysis of amorpha-4,11-diene. The results showed that all of the engineered yeasts could produce amorpha-4,11-diene. The yield of the product was improved with increasing ADS gene copies while no deleterious effect on the strain growth was found. Moreover, the product yield of the engineered yeast co-transformed with multiple plasmids was much higher than the total yield of the different engineered yeasts with only one plasmid, respectively. In conclusion, there was a distinct synergistic effect between different recombinant ADS plasmids within one cell. Our results facilitate the construction of the engineered yeast with high yield of amorpha-4,11-diene, the precursor of artemisinin.