The removal of antibiotics from water by clay minerals has become the focus of research due to their strong adsorptive ability. In this study, adsorption of chlortetracycline (CTC) onto rectories was conducted and the...The removal of antibiotics from water by clay minerals has become the focus of research due to their strong adsorptive ability. In this study, adsorption of chlortetracycline (CTC) onto rectories was conducted and the effects of time, concentration, temperature and pH were investigated. Experimental results showed that adsorption equilibrium was reached in 8 h. Based on the Langmuir model, the maximum adsorption capacity of CTC on rectories was 177.7 mg·g 1 at room temperature. By the study on adsorption dynamics, it is found that the kinetic date fit the pseudo-second-order model well. The adsorption of CTC by rectories is endothermic and the free energy is in the range of 10 to 30 kJ·mol 1 . The pH value of solution has significant effects on adsorption and the optimal pH is at acidity (pH 2-6). At concentration of 2500 mg·L 1 , the intercalated CTC produces an interlayer space with a height of 1.38 nm, which is 1.12 nm in raw rectories, suggesting that the adsorption occurs between layers of rectories.展开更多
In this paper, in order to get the target microbe which has high cellulose bio-degradation ability, we collected soil samples from environment rich in cellulose. Carboxymethyl cellulose sodium gel plate and filter pap...In this paper, in order to get the target microbe which has high cellulose bio-degradation ability, we collected soil samples from environment rich in cellulose. Carboxymethyl cellulose sodium gel plate and filter paper plate were used for microbe screening, and finally we got a strain named MI which has the highest cellulase producing ability, and it has been identified as Penicilium oxalicum by morphological and molecular biological identification. We have studied cellulose degradation ability of this strain under different conditions such as pH value, temperature and inoculating time. The results showed that CMCase which belongs to acid enzyme, could achieve its maximum enzyme activity 489.96 U/ml when the optimal pH value was 4. The FPAase could achieve its maximum enzyme activity 1,595.45 U/ml when the optimal pH value was 4, too. The optimal ferment temperature of CMCase is 50℃ when achieved the maximum of enzyme activity at the second day, whereas the FPAase could reach its tip top on the third day, So the optimal ferment temperature of FPAase is also 50℃.展开更多
The trimmed mean is one of the most common estimators of location for symmetrical distributions, whose effect depends on whether the trim rate matches the proportion of contaminated data. Based on the geometric charac...The trimmed mean is one of the most common estimators of location for symmetrical distributions, whose effect depends on whether the trim rate matches the proportion of contaminated data. Based on the geometric characteristics of the curve of the trimmed variance function, the authors propose two kinds of adaptive trimmed mean algorithms. The accuracy of the estimators is compared with that of other often-used estimates, such as sample mean, trimmed mean, trimean, and median, by means of simulation method. The results show that the accuracy of the adaptive derivative optimization trimmed mean method is close to the optimum performance in case of medium contamination （the contamination rate is less than 50%）. Under high contamination situation （the contamination rate equals 8070）, the performance of the estimates is comparable to that of the median and is superior to other counterparts.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities (2011YXL056)the National Program of Control and Treatment of Water Pollution (2009ZX07424-002)
文摘The removal of antibiotics from water by clay minerals has become the focus of research due to their strong adsorptive ability. In this study, adsorption of chlortetracycline (CTC) onto rectories was conducted and the effects of time, concentration, temperature and pH were investigated. Experimental results showed that adsorption equilibrium was reached in 8 h. Based on the Langmuir model, the maximum adsorption capacity of CTC on rectories was 177.7 mg·g 1 at room temperature. By the study on adsorption dynamics, it is found that the kinetic date fit the pseudo-second-order model well. The adsorption of CTC by rectories is endothermic and the free energy is in the range of 10 to 30 kJ·mol 1 . The pH value of solution has significant effects on adsorption and the optimal pH is at acidity (pH 2-6). At concentration of 2500 mg·L 1 , the intercalated CTC produces an interlayer space with a height of 1.38 nm, which is 1.12 nm in raw rectories, suggesting that the adsorption occurs between layers of rectories.
文摘In this paper, in order to get the target microbe which has high cellulose bio-degradation ability, we collected soil samples from environment rich in cellulose. Carboxymethyl cellulose sodium gel plate and filter paper plate were used for microbe screening, and finally we got a strain named MI which has the highest cellulase producing ability, and it has been identified as Penicilium oxalicum by morphological and molecular biological identification. We have studied cellulose degradation ability of this strain under different conditions such as pH value, temperature and inoculating time. The results showed that CMCase which belongs to acid enzyme, could achieve its maximum enzyme activity 489.96 U/ml when the optimal pH value was 4. The FPAase could achieve its maximum enzyme activity 1,595.45 U/ml when the optimal pH value was 4, too. The optimal ferment temperature of CMCase is 50℃ when achieved the maximum of enzyme activity at the second day, whereas the FPAase could reach its tip top on the third day, So the optimal ferment temperature of FPAase is also 50℃.
基金supported in part by the National Basic Research Program of China under Grant No. 2010CB950703the Natural Science Foundation of China under Grant No.10901020the Fundamental Research Funds for the Central Universities
文摘The trimmed mean is one of the most common estimators of location for symmetrical distributions, whose effect depends on whether the trim rate matches the proportion of contaminated data. Based on the geometric characteristics of the curve of the trimmed variance function, the authors propose two kinds of adaptive trimmed mean algorithms. The accuracy of the estimators is compared with that of other often-used estimates, such as sample mean, trimmed mean, trimean, and median, by means of simulation method. The results show that the accuracy of the adaptive derivative optimization trimmed mean method is close to the optimum performance in case of medium contamination （the contamination rate is less than 50%）. Under high contamination situation （the contamination rate equals 8070）, the performance of the estimates is comparable to that of the median and is superior to other counterparts.
