A genetically engineered Escherichia coli JM109 harboring pLF3 was used to produce a hybrid ex-tracellular β-glucanase. Starting with enzyme production medium, glycerol and yeast extract combined with NaNO3 were scre...A genetically engineered Escherichia coli JM109 harboring pLF3 was used to produce a hybrid ex-tracellular β-glucanase. Starting with enzyme production medium, glycerol and yeast extract combined with NaNO3 were screened to be the most suitable carbon and nitrogen source, respectively. Analysis of six components of the enzyme production medium by employing statistical optimization methods such as Plackett-Burman design and steepest ascent showed that yeast extract was the only significant variable and its best concentration for enzyme production was 12g·L-1. After optimization of the medium, 297.71U·ml-1 of β-glucanase activity in the medium and 352350U·g-1 of β-glucanase selectivity could be obtained, which were 14 and 72 folds higher than those ob-tained from original medium, respectively. Even higher enzyme activities were achieved by batch cultivations in a conventional stirred bioreactor on the optimized medium.展开更多
Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures,particularly in seismically active regions.Shear wave velocity(V_(S))is a key parameter in such analysis,although the eco...Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures,particularly in seismically active regions.Shear wave velocity(V_(S))is a key parameter in such analysis,although the economy and other factors restrict its direct field measurement in many cases.Various V_(S)-SPT-N correlations are routinely incorporated in seismic hazard analysis to estimate the value of V_(S).However,many uncertainties question the reliability of these estimated V_(S)values.This paper comes up with a statistical approach to take care of such uncertainties involved in V_(S)calculations.The measured SPT-N values from all the critical boreholes were converted into statistical parameters and passed through various correlations to estimate V_(S)at different depths.The effect of different soil layers in the boreholes on the V_(S)estimation was also taken into account.Further,the average shear wave velocity of the top 30 m soil coverV_(S30))is estimated after accounting for various epistemic and aleatoric uncertainties.The scattering nature of the V_(S)values estimated using different V_(S)-N correlations was reduced significantly with the application of the methodology.Study results further clearly demonstrated the potential of the approach to eliminate various uncertainties involved in the estimation of V_(S)30 using general and soil-specific correlations.展开更多
基金Supported by the National Natural Science Foundation of China (No.20306025)the Xiamen Science and Technology Pro-ject (No.3502Z20055017).
文摘A genetically engineered Escherichia coli JM109 harboring pLF3 was used to produce a hybrid ex-tracellular β-glucanase. Starting with enzyme production medium, glycerol and yeast extract combined with NaNO3 were screened to be the most suitable carbon and nitrogen source, respectively. Analysis of six components of the enzyme production medium by employing statistical optimization methods such as Plackett-Burman design and steepest ascent showed that yeast extract was the only significant variable and its best concentration for enzyme production was 12g·L-1. After optimization of the medium, 297.71U·ml-1 of β-glucanase activity in the medium and 352350U·g-1 of β-glucanase selectivity could be obtained, which were 14 and 72 folds higher than those ob-tained from original medium, respectively. Even higher enzyme activities were achieved by batch cultivations in a conventional stirred bioreactor on the optimized medium.
文摘Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures,particularly in seismically active regions.Shear wave velocity(V_(S))is a key parameter in such analysis,although the economy and other factors restrict its direct field measurement in many cases.Various V_(S)-SPT-N correlations are routinely incorporated in seismic hazard analysis to estimate the value of V_(S).However,many uncertainties question the reliability of these estimated V_(S)values.This paper comes up with a statistical approach to take care of such uncertainties involved in V_(S)calculations.The measured SPT-N values from all the critical boreholes were converted into statistical parameters and passed through various correlations to estimate V_(S)at different depths.The effect of different soil layers in the boreholes on the V_(S)estimation was also taken into account.Further,the average shear wave velocity of the top 30 m soil coverV_(S30))is estimated after accounting for various epistemic and aleatoric uncertainties.The scattering nature of the V_(S)values estimated using different V_(S)-N correlations was reduced significantly with the application of the methodology.Study results further clearly demonstrated the potential of the approach to eliminate various uncertainties involved in the estimation of V_(S)30 using general and soil-specific correlations.
