I Was born in April, when spring is in the air, the sun shines, the sky is blue, and the fragrance of lilacs is everywhere. This year's birthday was unforgettable.As the SARS epidemic had broken out in Beijing, it...I Was born in April, when spring is in the air, the sun shines, the sky is blue, and the fragrance of lilacs is everywhere. This year's birthday was unforgettable.As the SARS epidemic had broken out in Beijing, it was spent under the threat of this killer disease.展开更多
The article establishes the patterns of urban snow disaster system and disaster chain based on the theory of regional disaster system. The patterns indicate that urban snow disaster is exacerbated mainly through the t...The article establishes the patterns of urban snow disaster system and disaster chain based on the theory of regional disaster system. The patterns indicate that urban snow disaster is exacerbated mainly through the traffic system. In addition, the paper sets up the vulnerability assessment index system and synthetically vulnerability assessment model of urban snow disaster which are mainly based on traffic system, and applies them in Chenzhou City. The results of assessment indicate that obvious geographical differences exist in the vulnerability of snow disaster bearing bodies: vulnerability of Chenzhou section of the Beijing-Zhuhai expressway is the highest in Chenzhou City, and the southeastern counties are more vulnerable than the northwest region. Furthermore, according to the snow disaster vulnerability dynamic process analysis, the vulnerability of Chenzhou City obviously increased in 2008 winter compared with that in 2007. Finally, the paper presents some suggestions for the locations of the emergency commands and the reserves of relief materials based on the evaluation results, and points out that disaster monitoring and relevant technical level should be strengthened for the minimization of traffic system's vulnerability.展开更多
Synthesis biodiesel using biocatalyst is an emerging and attracting alternative process to replace the conventional process. However, biocatalyst is easy to be deactivated by alcohol, which is a reactant in biodiesel ...Synthesis biodiesel using biocatalyst is an emerging and attracting alternative process to replace the conventional process. However, biocatalyst is easy to be deactivated by alcohol, which is a reactant in biodiesel synthesis reaction. Therefore, it is needed to develop new method to maintain the activity and stability of the biocatalyst during reaction. New method to be developed is by changing the reaction route which is using alcohol to the reaction route which is not using alcohol. Route reaction of non alcohol can be done by changing the alkyl alcohol with alkyl acetate. Both have the same function as alkyl supplier during the reaction. In this research, methyl acetate was reacted with triglyceride from fried palm oil using Candida rugosa lipase in batch reactor. The reactants and products were analyzed using HPLC. The effect of operating factors such as enzyme concentration, substrates ratio, operating temperature and addition of inhibitor using free and immobilized enzyme were investigated. The experimental results showed that 89.6% of triglyceride from fried palm oil was converted to its corresponding methyl esters under the condition of 4% wt lipase based on substrate weight, 1/12 mol rasio of oil/methyl acetate after 50 hours reaction using immobilized lipase. Stability test indicated that the activity of the immobilized biocatalyst was still remained after three reaction cycles.展开更多
文摘I Was born in April, when spring is in the air, the sun shines, the sky is blue, and the fragrance of lilacs is everywhere. This year's birthday was unforgettable.As the SARS epidemic had broken out in Beijing, it was spent under the threat of this killer disease.
基金Supported by National Natural Foundation of China (NSFC) (Grant No.40671003)
文摘The article establishes the patterns of urban snow disaster system and disaster chain based on the theory of regional disaster system. The patterns indicate that urban snow disaster is exacerbated mainly through the traffic system. In addition, the paper sets up the vulnerability assessment index system and synthetically vulnerability assessment model of urban snow disaster which are mainly based on traffic system, and applies them in Chenzhou City. The results of assessment indicate that obvious geographical differences exist in the vulnerability of snow disaster bearing bodies: vulnerability of Chenzhou section of the Beijing-Zhuhai expressway is the highest in Chenzhou City, and the southeastern counties are more vulnerable than the northwest region. Furthermore, according to the snow disaster vulnerability dynamic process analysis, the vulnerability of Chenzhou City obviously increased in 2008 winter compared with that in 2007. Finally, the paper presents some suggestions for the locations of the emergency commands and the reserves of relief materials based on the evaluation results, and points out that disaster monitoring and relevant technical level should be strengthened for the minimization of traffic system's vulnerability.
文摘Synthesis biodiesel using biocatalyst is an emerging and attracting alternative process to replace the conventional process. However, biocatalyst is easy to be deactivated by alcohol, which is a reactant in biodiesel synthesis reaction. Therefore, it is needed to develop new method to maintain the activity and stability of the biocatalyst during reaction. New method to be developed is by changing the reaction route which is using alcohol to the reaction route which is not using alcohol. Route reaction of non alcohol can be done by changing the alkyl alcohol with alkyl acetate. Both have the same function as alkyl supplier during the reaction. In this research, methyl acetate was reacted with triglyceride from fried palm oil using Candida rugosa lipase in batch reactor. The reactants and products were analyzed using HPLC. The effect of operating factors such as enzyme concentration, substrates ratio, operating temperature and addition of inhibitor using free and immobilized enzyme were investigated. The experimental results showed that 89.6% of triglyceride from fried palm oil was converted to its corresponding methyl esters under the condition of 4% wt lipase based on substrate weight, 1/12 mol rasio of oil/methyl acetate after 50 hours reaction using immobilized lipase. Stability test indicated that the activity of the immobilized biocatalyst was still remained after three reaction cycles.
