Selenium (Se) in the environment and food chains was greatlyrelated to animal deve- lopment and human health. Soils are the mainsources of Se in ecosystem. Numerous studies have been carried toinvestigate relationship...Selenium (Se) in the environment and food chains was greatlyrelated to animal deve- lopment and human health. Soils are the mainsources of Se in ecosystem. Numerous studies have been carried toinvestigate relationships between Se and S in soils. Xu (1992)reported that Se and S had similar chemical and physical propertiesso some factors influencing the uptake and toxicity of Se areattributed to the interaction of Se with S. Therefore, in order tocontrol and improve soil Se conditions, i.e., to reduce the Secontents of crops in Se-toxic soils or to increase the crop Secontents in Se-deficient soils by agricultural methods, S should beconsidered as an important factor.展开更多
Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics a...Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics and olefins were employed in this work. The desulfurization rates were above 90% on these two types of model gasoline using formic acid and HaPW12O40 （0.8 mol·L-1）, indicating that the presence of aromatics and olefins has no effect on the desulfurization rate. High temperature （above 90 ℃） was more favorable to the process for desulfurization. Four hours was considered to be the proper treating time for the sulfur removal. In addition, aqueous phase of acids could be recycled at least 4 times without decreasing desulfurization rate. Finally, the possible process for the integration of condensation desulfurization into the existing refinery process for the production of gasoline with low sulfur content was proposed.展开更多
This paper reports a sustainable,water-assisted,solid-state method for synthesizing ammonium nickel molybdate（（NH4）HNi2（OH）2（MoO4）2,ANM）,a precursor for an unsupported hydrodesulfurization（HDS） catalyst.The ...This paper reports a sustainable,water-assisted,solid-state method for synthesizing ammonium nickel molybdate（（NH4）HNi2（OH）2（MoO4）2,ANM）,a precursor for an unsupported hydrodesulfurization（HDS） catalyst.The associated ANM formation mechanism is also discussed.The synthesis route consists of physical mixing of the raw materials,water-assisted grinding and heating.The formation mechanism involves replacement of a Mo atom by a Ni atom,generating the metastable intermediate（NH4）4（NiH6Mo6O（24））·5H2O.Heating of this intermediate at 120 ℃ removes the added water and produces ANM.Catalysts prepared by this method exhibit almost the same physicochemical properties and catalytic performance during the HDS of dibenzothiophene as materials made from ANM synthesized by a chemical precipitation procedure.Compared with traditional hydrothermal or chemical precipitation methods,this water-assisted,solid-state synthesis provides several significant advantages,including simplifying the synthetic procedure,reducing waste and energy costs and increasing product yields.These features will be highly important with regard to allowing the application of ANM in industrial-scale processes involving HDS reactions.This water-assisted,solid-state strategy can also be extended to the synthesis of isomorphous compounds such as ammonium cobalt（zinc and copper） molybdate.展开更多
In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison ...In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.展开更多
Using blind dock method,we find that thioflavin-T(ThT) can bind to both monomers and fibrils of the full-length β-amyloid peptide(Aβ1-42) and has a higher binding affinity to the fibrils.It is shown that the hydroph...Using blind dock method,we find that thioflavin-T(ThT) can bind to both monomers and fibrils of the full-length β-amyloid peptide(Aβ1-42) and has a higher binding affinity to the fibrils.It is shown that the hydrophobic interaction between the ligand(ThT) and substrate(Aβ1-42) are stronger than hydrogen bonds.Furthermore,ThT tends to be located near the C-terminus of Aβ monomer through hydrophobic and electrostatic interactions,while it tends to contact the residues Met35 and Gly27 of the fibril surface mainly through hydrophobic interaction.Finally,according to the docking results and ThT fluorescence assay,a kinetic equation is proposed to deduce the aggregation rate coefficient of Aβ1-42.展开更多
Performance of simultaneous desulfurization and denitration using the solution of NaClO2 and NaClO as new-style complex absorbent was investigated experimentally in self-designed bench scale bubbling reactor. The effe...Performance of simultaneous desulfurization and denitration using the solution of NaClO2 and NaClO as new-style complex absorbent was investigated experimentally in self-designed bench scale bubbling reactor. The effects of main parameters, such as the concentrations of NaClO2 and of NaClO, solution pH and reaction temperature and so on, on removal efficiencies of SO2 and NOx, were examined, then the optimal conditions were established, in which the molar ratio of NaClO to NaClO2 was 1：1, the reaction temperature was 50℃ and the solution pH was 5.5. The removal efficiencies of SO2 and NO under the optimal conditions were 100% and 89.2%, respectively. The mechanism of simultaneous removal based on complex absorbent was proposed by analyzing the removal products and the electrode potentials of related species, namely SO2 and NO are oxi- dized by chlorite anion, hypochlorite, chlorine dioxide and chlorine contained in complex absorbent. In thermodynamic aspect, simultaneous desulfurization and denitration reactions in liquid phase can happen spontaneously and completely, and are all exothermic reactions. It was confirmed by kinetics that for simultaneous desulfurization and denitration, the reaction order and average activation energy of SO2 were 1 and 21.6 kJ·mol^-1, respectively, and those of NO were 1 and 8.2 kJ·mol^-1, respectively.展开更多
基金Project(No.00041405)supported by the Natural Science Foundation of Anhui Province,China
文摘Selenium (Se) in the environment and food chains was greatlyrelated to animal deve- lopment and human health. Soils are the mainsources of Se in ecosystem. Numerous studies have been carried toinvestigate relationships between Se and S in soils. Xu (1992)reported that Se and S had similar chemical and physical propertiesso some factors influencing the uptake and toxicity of Se areattributed to the interaction of Se with S. Therefore, in order tocontrol and improve soil Se conditions, i.e., to reduce the Secontents of crops in Se-toxic soils or to increase the crop Secontents in Se-deficient soils by agricultural methods, S should beconsidered as an important factor.
基金Supported by the National Natural Science Foundation of China(No.20126008)
文摘Aqueous phase of acids as catalysts for the desulfurization of gasoline by condensation of thiophenes with form- aldehyde in a biphasic system was investigated. Two types of model gasoline with and without aromatics and olefins were employed in this work. The desulfurization rates were above 90% on these two types of model gasoline using formic acid and HaPW12O40 （0.8 mol·L-1）, indicating that the presence of aromatics and olefins has no effect on the desulfurization rate. High temperature （above 90 ℃） was more favorable to the process for desulfurization. Four hours was considered to be the proper treating time for the sulfur removal. In addition, aqueous phase of acids could be recycled at least 4 times without decreasing desulfurization rate. Finally, the possible process for the integration of condensation desulfurization into the existing refinery process for the production of gasoline with low sulfur content was proposed.
基金supported by the National Natural Science Fundation of China(U1162203,21106185)the Fundamental Research Funds for the Central Universities(15CX02023A,15CX06051A)Financial support from Petro China Corporation Limited~~
文摘This paper reports a sustainable,water-assisted,solid-state method for synthesizing ammonium nickel molybdate（（NH4）HNi2（OH）2（MoO4）2,ANM）,a precursor for an unsupported hydrodesulfurization（HDS） catalyst.The associated ANM formation mechanism is also discussed.The synthesis route consists of physical mixing of the raw materials,water-assisted grinding and heating.The formation mechanism involves replacement of a Mo atom by a Ni atom,generating the metastable intermediate（NH4）4（NiH6Mo6O（24））·5H2O.Heating of this intermediate at 120 ℃ removes the added water and produces ANM.Catalysts prepared by this method exhibit almost the same physicochemical properties and catalytic performance during the HDS of dibenzothiophene as materials made from ANM synthesized by a chemical precipitation procedure.Compared with traditional hydrothermal or chemical precipitation methods,this water-assisted,solid-state synthesis provides several significant advantages,including simplifying the synthetic procedure,reducing waste and energy costs and increasing product yields.These features will be highly important with regard to allowing the application of ANM in industrial-scale processes involving HDS reactions.This water-assisted,solid-state strategy can also be extended to the synthesis of isomorphous compounds such as ammonium cobalt（zinc and copper） molybdate.
基金Supported by the National Natural Science Foundation of China （20676071, 20836004）.
文摘In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.
基金supported by the National Natural Science Foundation of China(20825206,20091350914 & 90913003)the Specialized Research Fund for the Doctoral Program of Higher Education (20100002110069)
文摘Using blind dock method,we find that thioflavin-T(ThT) can bind to both monomers and fibrils of the full-length β-amyloid peptide(Aβ1-42) and has a higher binding affinity to the fibrils.It is shown that the hydrophobic interaction between the ligand(ThT) and substrate(Aβ1-42) are stronger than hydrogen bonds.Furthermore,ThT tends to be located near the C-terminus of Aβ monomer through hydrophobic and electrostatic interactions,while it tends to contact the residues Met35 and Gly27 of the fibril surface mainly through hydrophobic interaction.Finally,according to the docking results and ThT fluorescence assay,a kinetic equation is proposed to deduce the aggregation rate coefficient of Aβ1-42.
文摘Performance of simultaneous desulfurization and denitration using the solution of NaClO2 and NaClO as new-style complex absorbent was investigated experimentally in self-designed bench scale bubbling reactor. The effects of main parameters, such as the concentrations of NaClO2 and of NaClO, solution pH and reaction temperature and so on, on removal efficiencies of SO2 and NOx, were examined, then the optimal conditions were established, in which the molar ratio of NaClO to NaClO2 was 1：1, the reaction temperature was 50℃ and the solution pH was 5.5. The removal efficiencies of SO2 and NO under the optimal conditions were 100% and 89.2%, respectively. The mechanism of simultaneous removal based on complex absorbent was proposed by analyzing the removal products and the electrode potentials of related species, namely SO2 and NO are oxi- dized by chlorite anion, hypochlorite, chlorine dioxide and chlorine contained in complex absorbent. In thermodynamic aspect, simultaneous desulfurization and denitration reactions in liquid phase can happen spontaneously and completely, and are all exothermic reactions. It was confirmed by kinetics that for simultaneous desulfurization and denitration, the reaction order and average activation energy of SO2 were 1 and 21.6 kJ·mol^-1, respectively, and those of NO were 1 and 8.2 kJ·mol^-1, respectively.
