The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry （CD-IMS）...The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry （CD-IMS）. The corresponding electron attachment rate constants varied from 1.26×10-8 cm3/（molecules s） to 8.24×10-9 cm3/（molecules s） as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ionmolecule reaction rate constants for the further reaction between Cl^- and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl- and CHCl3 are the first time detected using CD-IMS.展开更多
分别以麻疯树毛油、餐饮废油和食用玉米油为原料通过液体碱催化法制备生物柴油,对产品精制过程中涉及的分离甘油、去除过量甲醇和除皂等传统技术进行了评价、改善和优化。实验结果显示:采用离心法分离粗甲脂和甘油,所需时间比传统的重...分别以麻疯树毛油、餐饮废油和食用玉米油为原料通过液体碱催化法制备生物柴油,对产品精制过程中涉及的分离甘油、去除过量甲醇和除皂等传统技术进行了评价、改善和优化。实验结果显示:采用离心法分离粗甲脂和甘油,所需时间比传统的重力沉降法大大缩短,从6 h缩短至40 m in,且分离效果与之相同,达到88.0%,可以替代之;去除过量甲醇过程放在产品精制的第一步更有利于提高甲醇的回收率和减少工业应用时的设备投资;采用先加入质量分数0.2%的冰醋酸再用60℃温水的水洗法,较好地解决了水洗过程中的油水乳化难题,使水洗次数、时间、耗水量大为减少,效率提高。对于餐饮废油,要获得高纯度生物柴油产品(甲脂含量大于或等于96.5%),除了经过上述除杂步骤,还需通过精馏才能达到。展开更多
An extracellular chitinase produced by Paenibacillus pasadenensis CS0611was purified by ammoniumsulfate precipitation,HiTrap DEAE FF and HiLoad26/600Superdex200pg column chromatography.The apparent molecular mass dete...An extracellular chitinase produced by Paenibacillus pasadenensis CS0611was purified by ammoniumsulfate precipitation,HiTrap DEAE FF and HiLoad26/600Superdex200pg column chromatography.The apparent molecular mass determined by sodium dodecyl sulfate polyacrylamide gelelectrophoresis was69kDa.The optimum pH and optimum temperature of the chitinase were5.0and50°C,respectively.The enzyme showed high stability at alkaline pH values and temperaturesbelow40°C.Additionally,the metal ions Mn2+,Mg2+,and Co2+inhibited activity of the chitinase.Thechitinase was active on colloidal chitin with an apparent Km of4.41mg/mL and Vmax of1.08mg/min.Substrate spectrum analysis indicated that the chitinase reacted preferentially with the glucosidicbond between GlcNAc‐GlcNAc.The enzymatic hydrolysate was analyzed by high‐performance liquidchromatography and thin layer chromatography,and clearly showed that a subunit of(GlcNAc)2was the main hydrolysis product.展开更多
The separation of the by-product (The volume fraction of 3-picoline is 68.472 2% and 4-picoline 26. 517 6% .) in the synthesis of pyridine by dissociation extraction wasstudied. Six separation conditions of the dissoc...The separation of the by-product (The volume fraction of 3-picoline is 68.472 2% and 4-picoline 26. 517 6% .) in the synthesis of pyridine by dissociation extraction wasstudied. Six separation conditions of the dissociation extraction-the kind and the dosage ofextractant and organic solvent, the concentration of the extractant and separation temperature-wereinvestigated. Different levels of each factor were chosen to form an orthogonal test of six factorsand five levels. The results show that the volume ratio of 3-picoline and 4-picoline in organicphase is the highest when 24 mL picolines are separated at 0 t by 2. 0 mol/L p-toluenesulfonic andn-heptane whose dosages are 40 mL and 48 mL, respectively. The effect of the separation isconsiderably improved with repetition test. This process of dissociation extraction has commendablepotential for industrial exploitation.展开更多
To overcome the problem that soft sensor models cannot be updated with the process changes, a soft sensor modeling algorithm based on hybrid fuzzy c-means （FCM） algorithm and incremental support vector machines （I...To overcome the problem that soft sensor models cannot be updated with the process changes, a soft sensor modeling algorithm based on hybrid fuzzy c-means （FCM） algorithm and incremental support vector machines （ISVM） is proposed. This hybrid algorithm FCMISVM includes three parts： samples clustering based on FCM algorithm, learning algorithm based on ISVM, and heuristic sample displacement method. In the training process, the training samples are first clustered by the FCM algorithm, and then by training each clustering with the SVM algorithm, a sub-model is built to each clustering. In the predicting process, when an incremental sample that represents new operation information is introduced in the model, the fuzzy membership function of the sample to each clustering is first computed by the FCM algorithm. Then, a corresponding SVM sub-model of the clustering with the largest fuzzy membership function is used to predict and perform incremental learning so the model can be updated on-line. An old sample chosen by heuristic sample displacement method is then discarded from the sub-model to control the size of the working set. The proposed method is applied to predict the p-xylene （PX） purity in the adsorption separation process. Simulation results indicate that the proposed method actually increases the model＇s adaptive abilities to various operation conditions and improves its generalization capability.展开更多
Design and control of pressure-swing distillation(PSD) with different heat integration modes for the separation of methyl acetate/methanol azeotrope are explored using Aspen Plus and Aspen Dynamics. First, an optimum ...Design and control of pressure-swing distillation(PSD) with different heat integration modes for the separation of methyl acetate/methanol azeotrope are explored using Aspen Plus and Aspen Dynamics. First, an optimum steady-state separation configuration conditions are obtained via taking the total annual cost(TAC) or total reboiler heat duty as the objective functions. The results show that about 27.68% and 25.40% saving in TAC can be achieved by the PSD with full and partial heat integration compared to PSD without heat integration. Second,temperature control tray locations are obtained according to the sensitivity criterion and singular value decomposition(SVD) analysis and the single-end control structure is effective based on the feed composition sensitivity analysis. Finally, the comparison of dynamic controllability is made among various control structures for PSD with partial and full heat integration. It is shown that both control structures of composition/temperature cascade and pressure-compensated temperature have a good dynamic response performance for PSD with heat integration facing feed flowrate and composition disturbances. However, PSD with full heat integration performs the poor controllability despite of a little bit of economy.展开更多
Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by ...Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.展开更多
Provskite-type catalysts, Ln0.6 Sr0.4 FexCo1-x O3 (Ln = Nd,Pr, Gd, Sm, La, 0＜x＜1) and Ln0.8Na0.2CoO3(Ln= La,Gd, Sm) were synthesized, their catalytic properties in the oxidative coupling of methane (OCM) were examin...Provskite-type catalysts, Ln0.6 Sr0.4 FexCo1-x O3 (Ln = Nd,Pr, Gd, Sm, La, 0＜x＜1) and Ln0.8Na0.2CoO3(Ln= La,Gd, Sm) were synthesized, their catalytic properties in the oxidative coupling of methane (OCM) were examined in a fixed-bed reactor. The former group presented higher activity in the OCM, but the main product was carbon dioxide. While the later group showed lower activity but much higher selectivity to C2 hydrocarbons compared with the former. Electrochemical measurements were conducted in a solid oxide membrane reactor with La0.8 Na0.2CoO3 as catalyst. The results showed that methane was oxidized to carbon dioxide and ethane by two parallel reactions. Ethane was oxidized to ethene and carbon dioxide. A fraction of ethene was oxidized deeply to carbon dioxide. The total selectivity to C2 hydrocarbons exceeded 70%. Based on the experimental results, a kinetic model was suggested to describe the reaction results.展开更多
Triptolide is an important active component of Tripterygium wilfordii Hook F (TWHF) and possesses anti-inflammatory, immunosuppressive, male anti-fertility, and anticancer properties. A new method combining different ...Triptolide is an important active component of Tripterygium wilfordii Hook F (TWHF) and possesses anti-inflammatory, immunosuppressive, male anti-fertility, and anticancer properties. A new method combining different techniques, including solid-liquid extraction, liquid-liquid partition, column chromatography and high-speed counter-current chromatography (HSCCC) but avoiding the use of chloroform, was developed for the isolation and purification of triptolide from the leaves of TWHF. 48 mg of triptolide at 96.5% purity was obtained from 1 kg of air-dried leaves of TWHF.展开更多
基金ACKNOWLEDGMENTS The work was support by the National Natural Science Foundation of China （No.20707025 and No.20907054） and the Excellent Youth Foundation of Anhui Province Scientific Committee （No.06045098）.
文摘The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry （CD-IMS）. The corresponding electron attachment rate constants varied from 1.26×10-8 cm3/（molecules s） to 8.24×10-9 cm3/（molecules s） as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ionmolecule reaction rate constants for the further reaction between Cl^- and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl- and CHCl3 are the first time detected using CD-IMS.
文摘分别以麻疯树毛油、餐饮废油和食用玉米油为原料通过液体碱催化法制备生物柴油,对产品精制过程中涉及的分离甘油、去除过量甲醇和除皂等传统技术进行了评价、改善和优化。实验结果显示:采用离心法分离粗甲脂和甘油,所需时间比传统的重力沉降法大大缩短,从6 h缩短至40 m in,且分离效果与之相同,达到88.0%,可以替代之;去除过量甲醇过程放在产品精制的第一步更有利于提高甲醇的回收率和减少工业应用时的设备投资;采用先加入质量分数0.2%的冰醋酸再用60℃温水的水洗法,较好地解决了水洗过程中的油水乳化难题,使水洗次数、时间、耗水量大为减少,效率提高。对于餐饮废油,要获得高纯度生物柴油产品(甲脂含量大于或等于96.5%),除了经过上述除杂步骤,还需通过精馏才能达到。
基金supported by the National Natural Science Foundation of China (21336002,21376096,21676104)~~
文摘An extracellular chitinase produced by Paenibacillus pasadenensis CS0611was purified by ammoniumsulfate precipitation,HiTrap DEAE FF and HiLoad26/600Superdex200pg column chromatography.The apparent molecular mass determined by sodium dodecyl sulfate polyacrylamide gelelectrophoresis was69kDa.The optimum pH and optimum temperature of the chitinase were5.0and50°C,respectively.The enzyme showed high stability at alkaline pH values and temperaturesbelow40°C.Additionally,the metal ions Mn2+,Mg2+,and Co2+inhibited activity of the chitinase.Thechitinase was active on colloidal chitin with an apparent Km of4.41mg/mL and Vmax of1.08mg/min.Substrate spectrum analysis indicated that the chitinase reacted preferentially with the glucosidicbond between GlcNAc‐GlcNAc.The enzymatic hydrolysate was analyzed by high‐performance liquidchromatography and thin layer chromatography,and clearly showed that a subunit of(GlcNAc)2was the main hydrolysis product.
文摘The separation of the by-product (The volume fraction of 3-picoline is 68.472 2% and 4-picoline 26. 517 6% .) in the synthesis of pyridine by dissociation extraction wasstudied. Six separation conditions of the dissociation extraction-the kind and the dosage ofextractant and organic solvent, the concentration of the extractant and separation temperature-wereinvestigated. Different levels of each factor were chosen to form an orthogonal test of six factorsand five levels. The results show that the volume ratio of 3-picoline and 4-picoline in organicphase is the highest when 24 mL picolines are separated at 0 t by 2. 0 mol/L p-toluenesulfonic andn-heptane whose dosages are 40 mL and 48 mL, respectively. The effect of the separation isconsiderably improved with repetition test. This process of dissociation extraction has commendablepotential for industrial exploitation.
基金Supported by the National Natural Science Foundation of China （60421002） and priority supported financially by ＂the New Century 151 Talent Project＂ of Zhejiang Province.
文摘To overcome the problem that soft sensor models cannot be updated with the process changes, a soft sensor modeling algorithm based on hybrid fuzzy c-means （FCM） algorithm and incremental support vector machines （ISVM） is proposed. This hybrid algorithm FCMISVM includes three parts： samples clustering based on FCM algorithm, learning algorithm based on ISVM, and heuristic sample displacement method. In the training process, the training samples are first clustered by the FCM algorithm, and then by training each clustering with the SVM algorithm, a sub-model is built to each clustering. In the predicting process, when an incremental sample that represents new operation information is introduced in the model, the fuzzy membership function of the sample to each clustering is first computed by the FCM algorithm. Then, a corresponding SVM sub-model of the clustering with the largest fuzzy membership function is used to predict and perform incremental learning so the model can be updated on-line. An old sample chosen by heuristic sample displacement method is then discarded from the sub-model to control the size of the working set. The proposed method is applied to predict the p-xylene （PX） purity in the adsorption separation process. Simulation results indicate that the proposed method actually increases the model＇s adaptive abilities to various operation conditions and improves its generalization capability.
文摘Design and control of pressure-swing distillation(PSD) with different heat integration modes for the separation of methyl acetate/methanol azeotrope are explored using Aspen Plus and Aspen Dynamics. First, an optimum steady-state separation configuration conditions are obtained via taking the total annual cost(TAC) or total reboiler heat duty as the objective functions. The results show that about 27.68% and 25.40% saving in TAC can be achieved by the PSD with full and partial heat integration compared to PSD without heat integration. Second,temperature control tray locations are obtained according to the sensitivity criterion and singular value decomposition(SVD) analysis and the single-end control structure is effective based on the feed composition sensitivity analysis. Finally, the comparison of dynamic controllability is made among various control structures for PSD with partial and full heat integration. It is shown that both control structures of composition/temperature cascade and pressure-compensated temperature have a good dynamic response performance for PSD with heat integration facing feed flowrate and composition disturbances. However, PSD with full heat integration performs the poor controllability despite of a little bit of economy.
基金the financial support from the National Natural Science Foundation of China(No.51774041)。
文摘Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.
基金This work was supported supported by the Center Petrochemical Company of China (X599027).
文摘Provskite-type catalysts, Ln0.6 Sr0.4 FexCo1-x O3 (Ln = Nd,Pr, Gd, Sm, La, 0＜x＜1) and Ln0.8Na0.2CoO3(Ln= La,Gd, Sm) were synthesized, their catalytic properties in the oxidative coupling of methane (OCM) were examined in a fixed-bed reactor. The former group presented higher activity in the OCM, but the main product was carbon dioxide. While the later group showed lower activity but much higher selectivity to C2 hydrocarbons compared with the former. Electrochemical measurements were conducted in a solid oxide membrane reactor with La0.8 Na0.2CoO3 as catalyst. The results showed that methane was oxidized to carbon dioxide and ethane by two parallel reactions. Ethane was oxidized to ethene and carbon dioxide. A fraction of ethene was oxidized deeply to carbon dioxide. The total selectivity to C2 hydrocarbons exceeded 70%. Based on the experimental results, a kinetic model was suggested to describe the reaction results.
基金Supported by the National Natural Science Foundation of China （20576113） Zhejiang Provincial Natural Science Foundation of China （R4090358）
文摘Triptolide is an important active component of Tripterygium wilfordii Hook F (TWHF) and possesses anti-inflammatory, immunosuppressive, male anti-fertility, and anticancer properties. A new method combining different techniques, including solid-liquid extraction, liquid-liquid partition, column chromatography and high-speed counter-current chromatography (HSCCC) but avoiding the use of chloroform, was developed for the isolation and purification of triptolide from the leaves of TWHF. 48 mg of triptolide at 96.5% purity was obtained from 1 kg of air-dried leaves of TWHF.
