No abstract

Salvianic acid A (SAA), as the main bioactive component of the traditional Chinese herb Salvia miltiorrhiza, has important application value in the treatment of cardiovascular diseases. In this study, a two-step bioprocess for the preparation of SAA from l-DOPA was developed. In the first step, l-DOPA was transformed to 3,4-dihydroxyphenylalanine (DHPPA) using engineered Escherichia coli cells expressing membrane-bound L-amino acid deaminase from Proteus vulgaris. After that, the unpurified DHPPA was directly converted into SAA by permeabilized recombinant E. coli cells co-expressing d-lactate dehydrogenase from Pediococcus acidilactici and formate dehydrogenase from Mycobacterium vaccae N10. Under optimized conditions, 48.3 mM of SAA could be prepared from 50 mM of l-DOPA, with a yield of 96.6%. Therefore, the bioprocess developed here was not only environmentally friendly, but also exhibited excellent production efficiency and, thus, is promising for industrial SAA production.

No abstract

In this work, a new forging process is proposed for bottom instead of the original casting process. In order to achieve better technological parameters combination, the finite element method (FEM) and orthogonal experiment were utilized to research the process of cylinder bottom forging. Forming maximum load, mould maximum wear and forging maximum damage were chosen as evaluating indicators. Billet preheating temperature, the mold preheating temperature, forging speed and friction factor were taken into consideration to analysis the influence on forming quality for the bottom. The significant factors and the optimal value, i.e. Billet preheating temperature (1150°C),the mold preheating temperature (350°C),the forging speed (50mm/s) and the friction factor (0.2) were determined. After the technological experiment, the qualified quality cylinder bottom can be manufactured by the optimized forging process.