No abstract

If large pressure fluctuation is observed in the draft tube of a Francis turbine at part-load operation, we have generally called it draft-tube-surge. As occurrence of this phenomenon seriously affects the limit of turbine operating range, extensive studies on the surge have been made since proposal of surge-frequency criterion given by Rheingans. According to the literature survey of related topics in recent IAHR symposiums on hydraulic machinery and systems, in which state-of-the-art contributions were mainly presented, a certain review of them may be desirable for an outlook on the future studies in this research field. Thus, in this review paper, the authors' previous attempts for the last three decades to challenge the following topics: a rational method for component test of a draft tube, nature of spiral vortex rope and its behavior in a draft tube and cavitation characteristics of pressure fluctuations, are introduced together with other related contributions, expecting that more useful and significant studies will be accomplished in the future.

The factors affecting enzymatic protein immobilization with microbial transglutaminase (MTG) were explored. As model proteins, enhanced green fluorescent protein (EGFP) and glutathione S-transferase (GST) were chosen and tagged with a neutral Gln-donor substrate peptide for MTG (Leu-Leu-Gln-Gly, LLQG-tag) at their C-terminus. To create a specific surface, displaying reactive Lys residues, to be cross-linked with the Gln residue in the LLQG-tag of target proteins by MTG catalysis, a polystyrene surface was physically coated with b-casein. Both recombinant proteins were immobilized onto the b-casein-coated surface only in the presence of active MTG, indicating that those proteins were enzymatically immobilized to the surface. MTG-mediated protein immobilization markedly depends on the pH and ionic strength of the reaction media. The optimal pH range of MTG-mediated immobilization of both recombinant proteins was around 5, at which point the MTG-catalyzed reaction in aqueous solution is not normally preferred. By utilizing a pH-dependent change in EGFP fluorescence, we found that the apparent pH at the surface is likely to be lower than bulk pH, this difference is not attributed to an optimal pH shift in MTG-mediated immobilization. On the other hand, lower yields of protein immobilization at higher ionic strength suggest that electrostatic interaction is a key factor governing MTG catalysis at a solid surface. The results of this study indicate that, in enzymatic catalysis at a solid surface, the concentration of substrates at the surface can enhance the catalytic efficiency, and this could alter the pH dependence of enzymatic catalysis.

No abstract

This research studied the involvement of mold powderand the influence of argon gas injection by means of a silicon oil-water model experiment and a 3-D numerical model. In this experiment argon gas was injected into the submergedentry nozzle through two kinds of cylinder-like porous refractory