为了探索单偶氮染料Acid red 37(AR37)降解的可行性及在活性氧物种作用下可能的反应位点和迁移转化机制,采用光活化过硫酸盐技术并根据单因素试验和响应曲面法优化试验考察了底物浓度,K2 S2O8用量和温度3个因素对AR37降解率的影响,得出A...为了探索单偶氮染料Acid red 37(AR37)降解的可行性及在活性氧物种作用下可能的反应位点和迁移转化机制,采用光活化过硫酸盐技术并根据单因素试验和响应曲面法优化试验考察了底物浓度,K2 S2O8用量和温度3个因素对AR37降解率的影响,得出AR37光催化降解的最优条件为:底物浓度90μmol·L^-1,K2S2O8用量8.47 mmol·L^-1和温度36℃.最后,利用GCMS对AR37在UV/K2S2O8体系下降解中间产物进行初步的分离与分析,并结合AR37前线电子云密度(FEDs)的理论计算结果对其降解途径进行推导.研究发现AR37在·SO4^-等活性氧物种作用下,C2、N8、N16、C17和C18等活性位点容易被自由基直接攻击或者发生电子转移反应,从而引起AR37分子中NN和C—N键断裂后的进一步羟基化反应,是其主要的降解途径.展开更多
A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was...A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was identified as Bacillus sp. based on morphological and physiochemical characterization. According to 16S rRNA gene sequencing data, the closest phylogenetic neighbor of strain YL was Bacillus amyloliquefaciens （99.54%）. After that, an optimization of culture conditions was carried out for the improvement of a-amylase production. Response surface methodology （RSM） was applied to evaluate the effect of medium components including wheat bran, cottonseed extract, yeast extract, starch, NaC1 and CaCl2. Three variables （wheat bran, cottonseed extract, and starch）, which were identified to significantly affect amylase production by Plackett-Burman design were further optimized using response surface methodology of Box-Behnken design （BBD）. The optimal concentrations estimated for each variable related to the maximum of amylase activity （86 kU/mL） were 10.80 g/L wheat bran, 9.90 g/L cottonseed extract, 0.5 g/L starch, 2.0 g/L yeast extract, 5.00 g/L NaCl and 2.00 g/L CaC12. The fermentation using optimized culture medium allowed a significant increase in amylase production （by 3-fold）. The improvement in the a-amylase production after optimization process can be considered adequate for large-scale applications.展开更多
A systematic approach was presented to develop the empirical model for predicting the ultimate tensile strength of AA5083-H111 aluminum alloy which is widely used in ship building industry by incorporating friction st...A systematic approach was presented to develop the empirical model for predicting the ultimate tensile strength of AA5083-H111 aluminum alloy which is widely used in ship building industry by incorporating friction stir welding(FSW) process parameters such as tool rotational speed,welding speed,and axial force.FSW was carried out considering three-factor five-level central composite rotatable design with full replications technique.Response surface methodology(RSM) was applied to developing linear regression model for establishing the relationship between the FSW process parameters and ultimate tensile strength.Analysis of variance(ANOVA) technique was used to check the adequacy of the developed model.The FSW process parameters were also optimized using response surface methodology(RSM) to maximize the ultimate tensile strength.The joint welded at a tool rotational speed of 1 000 r/min,a welding speed of 69 mm/min and an axial force of 1.33 t exhibits higher tensile strength compared with other joints.展开更多
文摘为了探索单偶氮染料Acid red 37(AR37)降解的可行性及在活性氧物种作用下可能的反应位点和迁移转化机制,采用光活化过硫酸盐技术并根据单因素试验和响应曲面法优化试验考察了底物浓度,K2 S2O8用量和温度3个因素对AR37降解率的影响,得出AR37光催化降解的最优条件为:底物浓度90μmol·L^-1,K2S2O8用量8.47 mmol·L^-1和温度36℃.最后,利用GCMS对AR37在UV/K2S2O8体系下降解中间产物进行初步的分离与分析,并结合AR37前线电子云密度(FEDs)的理论计算结果对其降解途径进行推导.研究发现AR37在·SO4^-等活性氧物种作用下,C2、N8、N16、C17和C18等活性位点容易被自由基直接攻击或者发生电子转移反应,从而引起AR37分子中NN和C—N键断裂后的进一步羟基化反应,是其主要的降解途径.
基金Project(31000350) supported by the National Natural Science Foundation of ChinaProject(2010CB630902) supported by the National Basic Research Program of China
文摘A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was identified as Bacillus sp. based on morphological and physiochemical characterization. According to 16S rRNA gene sequencing data, the closest phylogenetic neighbor of strain YL was Bacillus amyloliquefaciens （99.54%）. After that, an optimization of culture conditions was carried out for the improvement of a-amylase production. Response surface methodology （RSM） was applied to evaluate the effect of medium components including wheat bran, cottonseed extract, yeast extract, starch, NaC1 and CaCl2. Three variables （wheat bran, cottonseed extract, and starch）, which were identified to significantly affect amylase production by Plackett-Burman design were further optimized using response surface methodology of Box-Behnken design （BBD）. The optimal concentrations estimated for each variable related to the maximum of amylase activity （86 kU/mL） were 10.80 g/L wheat bran, 9.90 g/L cottonseed extract, 0.5 g/L starch, 2.0 g/L yeast extract, 5.00 g/L NaCl and 2.00 g/L CaC12. The fermentation using optimized culture medium allowed a significant increase in amylase production （by 3-fold）. The improvement in the a-amylase production after optimization process can be considered adequate for large-scale applications.
文摘A systematic approach was presented to develop the empirical model for predicting the ultimate tensile strength of AA5083-H111 aluminum alloy which is widely used in ship building industry by incorporating friction stir welding(FSW) process parameters such as tool rotational speed,welding speed,and axial force.FSW was carried out considering three-factor five-level central composite rotatable design with full replications technique.Response surface methodology(RSM) was applied to developing linear regression model for establishing the relationship between the FSW process parameters and ultimate tensile strength.Analysis of variance(ANOVA) technique was used to check the adequacy of the developed model.The FSW process parameters were also optimized using response surface methodology(RSM) to maximize the ultimate tensile strength.The joint welded at a tool rotational speed of 1 000 r/min,a welding speed of 69 mm/min and an axial force of 1.33 t exhibits higher tensile strength compared with other joints.
