目的探讨葡聚糖包裹的超顺磁性Fe_3O_4纳米颗粒(dextran-coated superparamagnetic iron oxides nanoparticles,dextrarr/SPlONP)作为间质注射的MRI造影剂的可行性。方法应用界面共沉淀法,制备dextran/SPIONP,用透射电镜、能谱分析、X...目的探讨葡聚糖包裹的超顺磁性Fe_3O_4纳米颗粒(dextran-coated superparamagnetic iron oxides nanoparticles,dextrarr/SPlONP)作为间质注射的MRI造影剂的可行性。方法应用界面共沉淀法,制备dextran/SPIONP,用透射电镜、能谱分析、X射线衍射、红外光谱测试、热重分析等方法对dextran/SPlONP的大小、磁性能等进行表征,并研究葡聚糖对SPlONP的影响。然后,将dextran/SPIONP稀释成不同剂量,兔舌粘膜下问质注射后的不同时间段,切取前哨淋巴结,行核磁共振波谱分析,确定dextran/SPIONP的最适剂量和最佳检测时间。结果dextran/SPION的平均直径为6～9nm,其表征与经典的共沉淀法制备的颗粒一致,具有超顺磁性,葡聚糖是影响SPIONP饱和磁化强度的主要因素。dextran/SPIONP用于间质注射的最适剂量为含铁量20μmol,最佳检测时间为注射后24h。结论用界面共沉淀法制备的dextran/SPIONP是一种适用于间质注射的MRI造影剂。展开更多
Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-ind...Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-index faceted iron oxide(Fe_(2)O_(3))nanocrystals anchored on reduced graphene oxide are developed as highly efficient bifunctional electrocatalysts,effectively improving the electrochemical performance of Li-S batteries.The theoretical and experimental results all indicate that high-index Fe_(2)O_(3)crystal facets with abundant unsaturated coordinated Fe sites not only have strong adsorption capacity to anchor polysulfides but also have high catalytic activity to facilitate the redox transformation of polysulfides and reduce the decomposition energy barrier of Li_(2)S.The Li-S batteries with these bifunctional electrocatalysts exhibit high initial capacity of 1521 mAh g^(-1)at 0.1 C and excellent cycling performance with a low capacity fading of 0.025%per cycle during 1600 cycles at 2 C.Even with a high sulfur loading of 9.41 mg cm^(-2),a remarkable areal capacity of 7.61 mAh cm^(-2)was maintained after 85 cycles.This work provides a new strategy to improve the catalytic activity of nanocrystals through the crystal facet engineering,deepening the comprehending of facet-dependent activity of catalysts in Li-S chemistry,affording a novel perspective for the design of advanced sulfur electrodes.展开更多
The kinetics of Fe3O4 formation by air oxidation of slightly acidic suspension of Fe（OH）2 was studied. The effects of initial concentration of Fe（Ⅱ）, temperature, partial pressure of oxygen, air flow rate and sti...The kinetics of Fe3O4 formation by air oxidation of slightly acidic suspension of Fe（OH）2 was studied. The effects of initial concentration of Fe（Ⅱ）, temperature, partial pressure of oxygen, air flow rate and stirring rate on the oxidation rate were investigated. The results show that Fe3O4 formation is composed of two-step reaction, the first step is the formation of Fe（OH）+2 by oxidation of Fe（OH）+ complex ions, the second step is the formation of magnetite by dehydration and deprotonation of Fe（OH）+ and Fe（OH）+2. The oxidation reaction is zero-order with respect to the concentration of Fe（Ⅱ） and around 0.5-order with respect to partial pressure of oxygen, and oxygen transfer process is rate-limiting step of oxidation reaction with apparent activation energy of 2.74 kJ·mol-1.展开更多
Electrochemical water treatment is an attractive technology for water desalination and softening due to its low energy consumption. Especially, capacitive Deionization(CDI) is promising as a future technology for wate...Electrochemical water treatment is an attractive technology for water desalination and softening due to its low energy consumption. Especially, capacitive Deionization(CDI) is promising as a future technology for water treatment. Graphene(rGO) has been intensively studied for CDI electrode because of its advantages such as excellent electrical conductivity and high specific surface area. However, its 2D dimensional structure with small specific capacitance, high resistance between layers and hydrophobicity degrades ion adsorption efficiency. In this work, we successfully prepared uniformly dispersed Fe3O4/rGO nanocomposite by simple thermal reactions and applied it as effective electrodes for CDI. Iron oxides play a role in uniting graphene sheets, and specific capacitance and wettability of electrodes are improved significantly;hence CDI performances are enhanced. The hardness removal of Fe3O4/rGO nanocomposite electrodes can reach 4.3 mg/g at applied voltage of 1.5V, which is 3 times higher than that of separate r GO electrodes.Thus this material is a promising candidate for water softening technology.展开更多
Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle forma...Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei isdetermined by the extent of aggregation of Fe_3O_4 /oligomer. Magnetic particles with diameter ranging from 5to 200 μm were prepared under different reaction conditions. Some polymerization parameters such as theconcentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution arediscussed and their effect on particle formation are explained by the proposed mechanism.展开更多
Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and ...Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties. Finally, the prepared magnetic composite particles latex is stable for several months.展开更多
文摘目的探讨葡聚糖包裹的超顺磁性Fe_3O_4纳米颗粒(dextran-coated superparamagnetic iron oxides nanoparticles,dextrarr/SPlONP)作为间质注射的MRI造影剂的可行性。方法应用界面共沉淀法,制备dextran/SPIONP,用透射电镜、能谱分析、X射线衍射、红外光谱测试、热重分析等方法对dextran/SPlONP的大小、磁性能等进行表征,并研究葡聚糖对SPlONP的影响。然后,将dextran/SPIONP稀释成不同剂量,兔舌粘膜下问质注射后的不同时间段,切取前哨淋巴结,行核磁共振波谱分析,确定dextran/SPIONP的最适剂量和最佳检测时间。结果dextran/SPION的平均直径为6～9nm,其表征与经典的共沉淀法制备的颗粒一致,具有超顺磁性,葡聚糖是影响SPIONP饱和磁化强度的主要因素。dextran/SPIONP用于间质注射的最适剂量为含铁量20μmol,最佳检测时间为注射后24h。结论用界面共沉淀法制备的dextran/SPIONP是一种适用于间质注射的MRI造影剂。
基金This work was supported by the National Natural Science Foundation of China(No.22078078)the Natural Science Foundation of Heilongjiang Province(No.LH2020B008)the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.2019DX13).
文摘Precisely regulating of the surface structure of crystalline materials to improve their catalytic activity for lithium polysulfides is urgently needed for high-performance lithium-sulfur(Li-S)batteries.Herein,high-index faceted iron oxide(Fe_(2)O_(3))nanocrystals anchored on reduced graphene oxide are developed as highly efficient bifunctional electrocatalysts,effectively improving the electrochemical performance of Li-S batteries.The theoretical and experimental results all indicate that high-index Fe_(2)O_(3)crystal facets with abundant unsaturated coordinated Fe sites not only have strong adsorption capacity to anchor polysulfides but also have high catalytic activity to facilitate the redox transformation of polysulfides and reduce the decomposition energy barrier of Li_(2)S.The Li-S batteries with these bifunctional electrocatalysts exhibit high initial capacity of 1521 mAh g^(-1)at 0.1 C and excellent cycling performance with a low capacity fading of 0.025%per cycle during 1600 cycles at 2 C.Even with a high sulfur loading of 9.41 mg cm^(-2),a remarkable areal capacity of 7.61 mAh cm^(-2)was maintained after 85 cycles.This work provides a new strategy to improve the catalytic activity of nanocrystals through the crystal facet engineering,deepening the comprehending of facet-dependent activity of catalysts in Li-S chemistry,affording a novel perspective for the design of advanced sulfur electrodes.
文摘The kinetics of Fe3O4 formation by air oxidation of slightly acidic suspension of Fe（OH）2 was studied. The effects of initial concentration of Fe（Ⅱ）, temperature, partial pressure of oxygen, air flow rate and stirring rate on the oxidation rate were investigated. The results show that Fe3O4 formation is composed of two-step reaction, the first step is the formation of Fe（OH）+2 by oxidation of Fe（OH）+ complex ions, the second step is the formation of magnetite by dehydration and deprotonation of Fe（OH）+ and Fe（OH）+2. The oxidation reaction is zero-order with respect to the concentration of Fe（Ⅱ） and around 0.5-order with respect to partial pressure of oxygen, and oxygen transfer process is rate-limiting step of oxidation reaction with apparent activation energy of 2.74 kJ·mol-1.
基金supported by international cooperation program for science and technology funded by the Ministry of Science,ICT&Future Planning(NRF-2014K1A3A1A09063208)
文摘Electrochemical water treatment is an attractive technology for water desalination and softening due to its low energy consumption. Especially, capacitive Deionization(CDI) is promising as a future technology for water treatment. Graphene(rGO) has been intensively studied for CDI electrode because of its advantages such as excellent electrical conductivity and high specific surface area. However, its 2D dimensional structure with small specific capacitance, high resistance between layers and hydrophobicity degrades ion adsorption efficiency. In this work, we successfully prepared uniformly dispersed Fe3O4/rGO nanocomposite by simple thermal reactions and applied it as effective electrodes for CDI. Iron oxides play a role in uniting graphene sheets, and specific capacitance and wettability of electrodes are improved significantly;hence CDI performances are enhanced. The hardness removal of Fe3O4/rGO nanocomposite electrodes can reach 4.3 mg/g at applied voltage of 1.5V, which is 3 times higher than that of separate r GO electrodes.Thus this material is a promising candidate for water softening technology.
基金Project 59573011 was supported by National Natural Science Foundation of China
文摘Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei isdetermined by the extent of aggregation of Fe_3O_4 /oligomer. Magnetic particles with diameter ranging from 5to 200 μm were prepared under different reaction conditions. Some polymerization parameters such as theconcentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution arediscussed and their effect on particle formation are explained by the proposed mechanism.
文摘Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties. Finally, the prepared magnetic composite particles latex is stable for several months.
