The optimization of cultural conditions for β glucanase production by Bacillus subtilis ZJF 1A5 was investigated in flask trials. Temperature had great effect on β glucanase production which maximized...The optimization of cultural conditions for β glucanase production by Bacillus subtilis ZJF 1A5 was investigated in flask trials. Temperature had great effect on β glucanase production which maximized at optimal temperature of 37℃ and decreased significantly when temperature was over 37℃.Charge quantity affected β glucanase production significantly. Adding oxygen vector N dodecane or acetic ether benefited β glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β glucanase production and the cultivation time span to reach the highest β glucanase activity. The optimal cultural conditions for β glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted by a second order polynomial model. The amount of β glucanase, α amylase and neutral protease produced by B subtilis ZJF 1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase.展开更多
This paper has developed a measurement approach that integrates price with the product technical content initiated by Lall et al.(2006),i.e.,dividing HS6-quantile products into high-end,middle-end and low-end levels t...This paper has developed a measurement approach that integrates price with the product technical content initiated by Lall et al.(2006),i.e.,dividing HS6-quantile products into high-end,middle-end and low-end levels through the quantile ranking of prices of the same product from different countries or regions in a target market.Our estimation has discovered that due to the lack of product price differentiation,traditional method for the measurement of product technical content overestimated technical content of the low-end segment in the same category of products while underestimated technical content of the high-end segment in the same category of products.Re-calculation based on Rodric's result indicates that specialness of Chinese exports is mainly reflected by high-end and middle-end products.In addition,the competition result of the sophistication of Chinese exports indicates that since the middle of the 1990 s,the sophistication of Chinese exports has remained relatively low compared with the average level of the world and developing countries;from an economic perspective,improvement in the sophistication of Chinese exports primarily derived from middle-end and low-end products;from a category-specific perspective,improvement in the sophistication of Chinese exports primarily derived from low-technology export products.展开更多
The modeling of volatility and correlation is important in order to calculate hedge ratios, value at risk estimates, CAPM （Capital Asset Pricing Model betas）, derivate pricing and risk management in general. Recent ...The modeling of volatility and correlation is important in order to calculate hedge ratios, value at risk estimates, CAPM （Capital Asset Pricing Model betas）, derivate pricing and risk management in general. Recent access to intra-daily high-frequency data for two of the most liquid contracts at the Nord Pool exchange has made it possible to apply new and promising methods for analyzing volatility and correlation. The concepts of realized volatility and realized correlation are applied, and this study statistically describes the distribution （both distributional properties and temporal dependencies） of electricity forward data from 2005 to 2009. The main findings show that the logarithmic realized volatility is approximately normally distributed, while realized correlation seems not to be. Further, realized volatility and realized correlation have a long-memory feature. There also seems to be a high correlation between realized correlation and volatilities and positive relations between trading volume and realized volatility and between trading volume and realized correlation. These results are to a large extent consistent with earlier studies of stylized facts of other financial and commodity markets.展开更多
This paper analyzed in depth the difference between the pricing of non- performing loan （NPL） securitization and that of ordinary asset securitization. It has explained the pricing thought and method of non-performi...This paper analyzed in depth the difference between the pricing of non- performing loan （NPL） securitization and that of ordinary asset securitization. It has explained the pricing thought and method of non-performing loan backed securities in connection with the particularity and complexity of non-performing loan and finally proposed some key problems which need to be emphasized during the pricing practice of non-performing loan backed securitization.展开更多
文摘The optimization of cultural conditions for β glucanase production by Bacillus subtilis ZJF 1A5 was investigated in flask trials. Temperature had great effect on β glucanase production which maximized at optimal temperature of 37℃ and decreased significantly when temperature was over 37℃.Charge quantity affected β glucanase production significantly. Adding oxygen vector N dodecane or acetic ether benefited β glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β glucanase production and the cultivation time span to reach the highest β glucanase activity. The optimal cultural conditions for β glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted by a second order polynomial model. The amount of β glucanase, α amylase and neutral protease produced by B subtilis ZJF 1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase.
基金an outcome of annual program under the Fundamental Research Funds for the Centrally-Administered Universities(Approval No.JBK130936)Research on the Upgrade Mechanism of Chinese Export Productssponsored by the Fundamental Research Funds for the Centrally-Administered Universitiesa contribution to the Third China Trade Research Group(CTRG) Conference
文摘This paper has developed a measurement approach that integrates price with the product technical content initiated by Lall et al.(2006),i.e.,dividing HS6-quantile products into high-end,middle-end and low-end levels through the quantile ranking of prices of the same product from different countries or regions in a target market.Our estimation has discovered that due to the lack of product price differentiation,traditional method for the measurement of product technical content overestimated technical content of the low-end segment in the same category of products while underestimated technical content of the high-end segment in the same category of products.Re-calculation based on Rodric's result indicates that specialness of Chinese exports is mainly reflected by high-end and middle-end products.In addition,the competition result of the sophistication of Chinese exports indicates that since the middle of the 1990 s,the sophistication of Chinese exports has remained relatively low compared with the average level of the world and developing countries;from an economic perspective,improvement in the sophistication of Chinese exports primarily derived from middle-end and low-end products;from a category-specific perspective,improvement in the sophistication of Chinese exports primarily derived from low-technology export products.
文摘The modeling of volatility and correlation is important in order to calculate hedge ratios, value at risk estimates, CAPM （Capital Asset Pricing Model betas）, derivate pricing and risk management in general. Recent access to intra-daily high-frequency data for two of the most liquid contracts at the Nord Pool exchange has made it possible to apply new and promising methods for analyzing volatility and correlation. The concepts of realized volatility and realized correlation are applied, and this study statistically describes the distribution （both distributional properties and temporal dependencies） of electricity forward data from 2005 to 2009. The main findings show that the logarithmic realized volatility is approximately normally distributed, while realized correlation seems not to be. Further, realized volatility and realized correlation have a long-memory feature. There also seems to be a high correlation between realized correlation and volatilities and positive relations between trading volume and realized volatility and between trading volume and realized correlation. These results are to a large extent consistent with earlier studies of stylized facts of other financial and commodity markets.
文摘This paper analyzed in depth the difference between the pricing of non- performing loan （NPL） securitization and that of ordinary asset securitization. It has explained the pricing thought and method of non-performing loan backed securities in connection with the particularity and complexity of non-performing loan and finally proposed some key problems which need to be emphasized during the pricing practice of non-performing loan backed securitization.
