Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically...Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically bonded BiVO_(4)/Bi_(19)Cl_(3)S_(27)(BVO/BCS)S-scheme heterojunction with a strong internal electric field is designed.Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO_(4) to Bi_(19)Cl_(3)S_(27) via the interfacial chemical bonding interactions(i.e.,Bi-O and Bi-S bonds)between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation,breaking the interfacial barrier and surface charge localization of Bi_(19)Cl_(3)S_(27),and further decreasing the energy of reactive hydrogen generation,CO_(2) absorption and activation.The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system.As a result,BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO_(2) reduction and the 24 h CO yield reaches 678.27μmol⋅g^(-1).This work provides an atomic-level insight into charge transfer kinetics and CO_(2) reduction mechanism in S-scheme heterojunction.展开更多
A convenient,cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides...A convenient,cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice,maize and millet.Twelve samples can be processed simultaneously in the method.During the extraction process,10%acetonitrile-water solutions containing 110μL of n-hexadecane were used to extract organochlorine pesticides.Subsequently,1.0 g sodium chloride was placed in the extract,and then centrifuged and cooled.The n-hexadecane drops containing the analytes were solidifi ed and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process.Limits of detection for organochlorine pesticides were 0.97–1.01μg/kg and the RSDs were in the range of 2.6%–8.5%.The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%.Compared with the published extraction methods,the developed method was used to analyze organochlorine pesticides in grains,being more environmentally friendly,which is suitable for the daily determination of organochlorine pesticides.展开更多
A dynamic microwave-assisted extraction（DMAE） method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors（liqu...A dynamic microwave-assisted extraction（DMAE） method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors（liquid/solid ratio K of solvent to ginseng powders（V/m）, irradiation time, irradiation temperature, extracting solution concentration, flow rate of solvent and microwave power） have been optimized by response surface methodology（RSM）. The optimum conditions of extraction are the liquid/solid ratio of 270 m L/g, the extraction temperature of 75 ℃, the extraction time of 35 min, ethanol concentration of 70%（V/V）, the solvent flow rate of 1.3 m L/min, and the microwave power of 500 W. The yield of ginsenosides obtained by the proposed DAME method is（15.0±0.7） %, which is well agreement with the yield predicted by the model. Compared with static microwave-assisted extraction, DMAE has a higher extraction yield and can avoid the degradation of ginsenoside.展开更多
In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extracti...In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extractive distillation process is established to achieve minimum energy requirement using the multi-objective genetic algorithm, and the results show that energy saving for this heat integration process is 15.7%. Finally, the control design is performed to investigate the system's dynamic performance, and three control structures are studied. The pressure-compensated temperature control scheme is proposed based on the first two control structures, and the dynamic responses reveal that the feed disturbances in both flow rate and benzene composition can be mitigated well.展开更多
Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the ...Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimen- sion. In this paper, local-geometric-projection method is applied to obtain fow dimensional element from various target radiating noise and the derived phase portraits show obviously low dimensional attractors. Furthermore, attractor dimension and cross prediction error are used for classification. It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.展开更多
基金financially supported by Outstanding Talent Research Fund of Zhengzhou University,China Postdoc toral Science Foundation(2020TQ0277,2020M682328)Central Plains Science and Technology Innovation Leader Project(214200510006)+1 种基金China Scholarship Council(No.202108410356)Postdoctoral Science Foundation of Henan province(202002010).
文摘Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically bonded BiVO_(4)/Bi_(19)Cl_(3)S_(27)(BVO/BCS)S-scheme heterojunction with a strong internal electric field is designed.Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO_(4) to Bi_(19)Cl_(3)S_(27) via the interfacial chemical bonding interactions(i.e.,Bi-O and Bi-S bonds)between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation,breaking the interfacial barrier and surface charge localization of Bi_(19)Cl_(3)S_(27),and further decreasing the energy of reactive hydrogen generation,CO_(2) absorption and activation.The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system.As a result,BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO_(2) reduction and the 24 h CO yield reaches 678.27μmol⋅g^(-1).This work provides an atomic-level insight into charge transfer kinetics and CO_(2) reduction mechanism in S-scheme heterojunction.
基金The study was financially supported by the National Science and Technology Support Program of China(Grant No.2013BAD16B08).
文摘A convenient,cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice,maize and millet.Twelve samples can be processed simultaneously in the method.During the extraction process,10%acetonitrile-water solutions containing 110μL of n-hexadecane were used to extract organochlorine pesticides.Subsequently,1.0 g sodium chloride was placed in the extract,and then centrifuged and cooled.The n-hexadecane drops containing the analytes were solidifi ed and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process.Limits of detection for organochlorine pesticides were 0.97–1.01μg/kg and the RSDs were in the range of 2.6%–8.5%.The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%.Compared with the published extraction methods,the developed method was used to analyze organochlorine pesticides in grains,being more environmentally friendly,which is suitable for the daily determination of organochlorine pesticides.
基金Supported by the National Natural Science Foundation of China(21006075)the Natural Science Foundation of Hubei Province(2014CFA115)+1 种基金the New Century Excellent Talents in University(NCET-11-0966)the Key Project of Chinese Ministry of Education(213024A)
文摘A dynamic microwave-assisted extraction（DMAE） method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors（liquid/solid ratio K of solvent to ginseng powders（V/m）, irradiation time, irradiation temperature, extracting solution concentration, flow rate of solvent and microwave power） have been optimized by response surface methodology（RSM）. The optimum conditions of extraction are the liquid/solid ratio of 270 m L/g, the extraction temperature of 75 ℃, the extraction time of 35 min, ethanol concentration of 70%（V/V）, the solvent flow rate of 1.3 m L/min, and the microwave power of 500 W. The yield of ginsenosides obtained by the proposed DAME method is（15.0±0.7） %, which is well agreement with the yield predicted by the model. Compared with static microwave-assisted extraction, DMAE has a higher extraction yield and can avoid the degradation of ginsenoside.
基金supported by the National Natural Science Foundation of China(grant number 21476261)the Key Research and Development Plan Project of Shandong Province(grant number 2015GGX107004)
文摘In this work, the extractive distillation with heat integration process is extended to separate the pressure-insensitive benzene-cyclohexane azeotrope by using furfural as the entrainer. The optimal design of extractive distillation process is established to achieve minimum energy requirement using the multi-objective genetic algorithm, and the results show that energy saving for this heat integration process is 15.7%. Finally, the control design is performed to investigate the system's dynamic performance, and three control structures are studied. The pressure-compensated temperature control scheme is proposed based on the first two control structures, and the dynamic responses reveal that the feed disturbances in both flow rate and benzene composition can be mitigated well.
文摘Signal processing in phase space based on nonlinear dynamics theory is a new method for underwater acoustic signal processing. One key problem when analyzing actual acoustic signal in phase space is how to reduce the noise and lower the embedding dimen- sion. In this paper, local-geometric-projection method is applied to obtain fow dimensional element from various target radiating noise and the derived phase portraits show obviously low dimensional attractors. Furthermore, attractor dimension and cross prediction error are used for classification. It concludes that combining these features representing the geometric and dynamical properties respectively shows effects in target classification.
