背景:普通外科手术中,磁吻合技术以操作简便、吻合迅速、对位准确、吻合质量确定、应用范围广泛等优点备受关注,但磁材料留置体内可能会对机体产生一些不良的影响,生物可降解纳米磁性复合材料有望解决此问题。目的:研制适用于外科吻合...背景:普通外科手术中,磁吻合技术以操作简便、吻合迅速、对位准确、吻合质量确定、应用范围广泛等优点备受关注,但磁材料留置体内可能会对机体产生一些不良的影响,生物可降解纳米磁性复合材料有望解决此问题。目的:研制适用于外科吻合用的生物可降解纳米钕铁硼磁性复合材料,并评价其主要磁性能、体外降解性能。方法:采用高能球磨法制备纳米钕铁硼微粒,以溶剂挥发法将纳米钕铁硼微粒与生物可降解材料聚乳酸/羟基乙酸共聚物复合(聚乳酸/羟基乙酸共聚物含量分别为2.5%、5%、7.5%、10%、20%、30%、40%、50%),在特定温度(60,80,100,120,140℃)、压力(6,8,10,12,14 MPa)条件下,以温压成型工艺压制生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料,检测其最大磁能积。采用磷酸盐缓冲液恒温振荡浸泡法进行生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料(聚乳酸与羟基乙酸摩尔比分别为90/10、70/20、50/50)体外降解实验,扫描电镜观察磁体降解前后显微形态结构变化及降解时间与聚乳酸/羟基乙酸共聚物摩尔比的关系。结果与结论:生物可降解纳米钕铁硼磁性复合材料的磁性能在一定范围内与纳米钕铁硼微粒含量、成型温度及成型压力呈正比,与聚乳酸/羟基乙酸共聚物含量呈反比。在工艺参数为温度120℃、压力12 MPa、聚乳酸/羟基乙酸共聚物含量为5%时其磁性能最佳,最大磁能积为45 k J/m3。生物可降解纳米钕铁硼磁性复合材料在体外的降解过程与聚乳酸/羟基乙酸共聚物内部组分的摩尔比密切相关,降解时间与聚乳酸含量呈正比,与羟基乙酸含量呈反比,聚乳酸与羟基乙酸摩尔比90/10、70/20、50/50组的降解高峰期分别为8,6,4周。展开更多
Melt-spun Nd9.5Fe81Zr3B6.5 ribbons were prepared by the melt-spinning technique. The phase evolution and magnetic properties were studied by X-ray diffraction, differential scanning calorimetry, transmission electron ...Melt-spun Nd9.5Fe81Zr3B6.5 ribbons were prepared by the melt-spinning technique. The phase evolution and magnetic properties were studied by X-ray diffraction, differential scanning calorimetry, transmission electron microscopy observations, and magnetization measurements. It is indicated that melt spinning at different wheel velocities caused the as-quenched ribbons to have distinctive structure. The phase transformation of the ribbons during annealing takes place in two steps： α-Fe transforms from the amorphous phase firstly, followed by formation of Nd2Fe14B phase. With increasing the initial quenching rate, the microstructure of optimally heat treated ribbons becomes coarser, which results in the weakening of the exchange coupling effect between the hard and soft phase. This leads to drastic deterioration of magnetic properties of annealed ribbons with increasing the initial quenching rate.展开更多
研究了N-氨乙基-γ-氨丙基三甲氧基硅烷在水溶液中以单层形式负载于磁铁矿纳米颗粒表面的方法,并研究了单分子层硅烷负载磁铁矿纳米颗粒吸附剂(monolayer of silane on magnetite nanoparticles,MSMNPs)的除磷性能.结果表明,在低浓度下...研究了N-氨乙基-γ-氨丙基三甲氧基硅烷在水溶液中以单层形式负载于磁铁矿纳米颗粒表面的方法,并研究了单分子层硅烷负载磁铁矿纳米颗粒吸附剂(monolayer of silane on magnetite nanoparticles,MSMNPs)的除磷性能.结果表明,在低浓度下(平衡浓度小于300 mg·L^(-1))硅烷在磁铁矿纳米颗粒表面产生单层吸附,而反应温度90℃以上或离子强度0.1 mol·L^(-1)NaCl以上可以使单层硅烷在磁铁矿纳米颗粒表面的覆盖度达到~100%.FTIR和XPS图谱显示负载的硅烷以化学键的形式与磁铁矿纳米颗粒表面相结合.单层硅烷负载不引起磁性强度的明显变化.MSMNPs对磷的吸附等温线更符合Langmuir模型,拟合得到的最大吸附量为7.59 mg·g^(-1).由于磷吸附位位于MSMNPs的最外面,磷的吸附及脱附均很快,30 min内达到90%以上,1 h内达到平衡.因此,MSMNPs是一种易分离因而可反复使用,并且可快速吸附与脱附污染物的新型吸附剂.展开更多
A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL...A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.展开更多
Ferromagnetic MnSb films were synthesized on Si wafers by physical vapor deposition. X-ray diffraction revealed that the films primarily consisted of MnSb alloy. Nanorods and nanoleaves were observed in the MnSb films...Ferromagnetic MnSb films were synthesized on Si wafers by physical vapor deposition. X-ray diffraction revealed that the films primarily consisted of MnSb alloy. Nanorods and nanoleaves were observed in the MnSb films by field-emission scanning electron microscopy. These nanorods had an average diameter of 20nm and a length of up to hundreds of nanometers. The nanoleaves had a width and thickness of about 100 and 20nm, respectively. Magnetic hysteresis loops were measured by an alternative gradient magnetometer, and the loops showed strong geometrical anisotropy.展开更多
The fluidization behavior of SiO2, ZnO and TiO2 non-magnetic nanoparticles was investigated in a magnetically fluidized bed （MFB） by adding coarse magnets. The effects of both the amount of coarse magnets and the ma...The fluidization behavior of SiO2, ZnO and TiO2 non-magnetic nanoparticles was investigated in a magnetically fluidized bed （MFB） by adding coarse magnets. The effects of both the amount of coarse magnets and the magnetic field intensity on the fluidization quality of these nanoparticles were investigated. The results show that the coarse magnets added to the bed lead to a reduction in the size of the aggregates formed naturally by the primary nanopartieles. As the macroscopic performances of improved fluidization quality, the bed expansion ratio increases whilst the minimum fluidization velocity decreases with increasing the magnetic field intensity, but for TiO2 nanoparticles there exists a suitable magnetic field intensity of 0.059 6 T. The optimal amounts of coarse magnets for SiO2, ZnO and TiO2 non-magnetic nanoparticles are 40%, 50% and 60% （mass fraction）, respectively. The bed expansion results analyzed by the Richardson-Zaki scaling law show that the exponents depend on both the amount of coarse magnets and the magnetic field intensity.展开更多
Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and super...Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and superparamagnetic properties.When the substrate temperature increases from room temperature to 400℃,Co particles gradually grow,and the degree of Co oxidation significantly decreases.Consequently,the saturation magnetization increases from 0.13 to 0.43 T at the same Co content by increasing the substrate temperature from room temperature to 400℃.At a high substrate temperature,conductive pathways form among some of the clustered Co particles.Thus,resistivity rapidly declines from 1600 to 76μΩ·m.The magnetoresistive characteristic of Co−TiO2 films is achieved even at resistivity of as low as 76μΩ·m.These results reveal that the obtained nanocomposite films have low Co oxidation,high magnetization and magnetoresistance at room temperature.展开更多
文摘背景:普通外科手术中,磁吻合技术以操作简便、吻合迅速、对位准确、吻合质量确定、应用范围广泛等优点备受关注,但磁材料留置体内可能会对机体产生一些不良的影响,生物可降解纳米磁性复合材料有望解决此问题。目的:研制适用于外科吻合用的生物可降解纳米钕铁硼磁性复合材料,并评价其主要磁性能、体外降解性能。方法:采用高能球磨法制备纳米钕铁硼微粒,以溶剂挥发法将纳米钕铁硼微粒与生物可降解材料聚乳酸/羟基乙酸共聚物复合(聚乳酸/羟基乙酸共聚物含量分别为2.5%、5%、7.5%、10%、20%、30%、40%、50%),在特定温度(60,80,100,120,140℃)、压力(6,8,10,12,14 MPa)条件下,以温压成型工艺压制生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料,检测其最大磁能积。采用磷酸盐缓冲液恒温振荡浸泡法进行生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料(聚乳酸与羟基乙酸摩尔比分别为90/10、70/20、50/50)体外降解实验,扫描电镜观察磁体降解前后显微形态结构变化及降解时间与聚乳酸/羟基乙酸共聚物摩尔比的关系。结果与结论:生物可降解纳米钕铁硼磁性复合材料的磁性能在一定范围内与纳米钕铁硼微粒含量、成型温度及成型压力呈正比,与聚乳酸/羟基乙酸共聚物含量呈反比。在工艺参数为温度120℃、压力12 MPa、聚乳酸/羟基乙酸共聚物含量为5%时其磁性能最佳,最大磁能积为45 k J/m3。生物可降解纳米钕铁硼磁性复合材料在体外的降解过程与聚乳酸/羟基乙酸共聚物内部组分的摩尔比密切相关,降解时间与聚乳酸含量呈正比,与羟基乙酸含量呈反比,聚乳酸与羟基乙酸摩尔比90/10、70/20、50/50组的降解高峰期分别为8,6,4周。
基金Projects(51201109,51001076)supported by the National Natural Science Foundation of ChinaProject(T201108)supported by Shenzhen Key Laboratory of Special Functional Materials,China
文摘Melt-spun Nd9.5Fe81Zr3B6.5 ribbons were prepared by the melt-spinning technique. The phase evolution and magnetic properties were studied by X-ray diffraction, differential scanning calorimetry, transmission electron microscopy observations, and magnetization measurements. It is indicated that melt spinning at different wheel velocities caused the as-quenched ribbons to have distinctive structure. The phase transformation of the ribbons during annealing takes place in two steps： α-Fe transforms from the amorphous phase firstly, followed by formation of Nd2Fe14B phase. With increasing the initial quenching rate, the microstructure of optimally heat treated ribbons becomes coarser, which results in the weakening of the exchange coupling effect between the hard and soft phase. This leads to drastic deterioration of magnetic properties of annealed ribbons with increasing the initial quenching rate.
基金supported by the National Natural Science Foundation of China(21336002,21222606,21376096)the Key Program of Guangdong Natural Science Foundation(S2013020013049)+1 种基金the Fundamental Research Funds for the Chinese Universities(2015PT002,2015ZP009)the Program of State Key Laboratory of Pulp and Paper Engineering(2015C04)~~
文摘A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.
文摘Ferromagnetic MnSb films were synthesized on Si wafers by physical vapor deposition. X-ray diffraction revealed that the films primarily consisted of MnSb alloy. Nanorods and nanoleaves were observed in the MnSb films by field-emission scanning electron microscopy. These nanorods had an average diameter of 20nm and a length of up to hundreds of nanometers. The nanoleaves had a width and thickness of about 100 and 20nm, respectively. Magnetic hysteresis loops were measured by an alternative gradient magnetometer, and the loops showed strong geometrical anisotropy.
基金Project(20776163) supported by the National Natural Science Foundation of ChinaProject(20070533121) supported by the PhD Programs Foundation of Ministry of Education of ChinaProject supported by the NSFC-JSPS Cooperation Program
文摘The fluidization behavior of SiO2, ZnO and TiO2 non-magnetic nanoparticles was investigated in a magnetically fluidized bed （MFB） by adding coarse magnets. The effects of both the amount of coarse magnets and the magnetic field intensity on the fluidization quality of these nanoparticles were investigated. The results show that the coarse magnets added to the bed lead to a reduction in the size of the aggregates formed naturally by the primary nanopartieles. As the macroscopic performances of improved fluidization quality, the bed expansion ratio increases whilst the minimum fluidization velocity decreases with increasing the magnetic field intensity, but for TiO2 nanoparticles there exists a suitable magnetic field intensity of 0.059 6 T. The optimal amounts of coarse magnets for SiO2, ZnO and TiO2 non-magnetic nanoparticles are 40%, 50% and 60% （mass fraction）, respectively. The bed expansion results analyzed by the Richardson-Zaki scaling law show that the exponents depend on both the amount of coarse magnets and the magnetic field intensity.
基金Project(2016YFE0205700)supported by the National Key Research and Development Program of ChinaProject(18JCYBJC18000)supported by the Natural Science Foundation of Tianjin City,China。
文摘Co−TiO2 nanocomposite films were prepared via magnetron sputtering at various substrate temperatures.The films comprise Co particles dispersed in an amorphous TiO2 matrix and exhibit coexisting ferromagnetic and superparamagnetic properties.When the substrate temperature increases from room temperature to 400℃,Co particles gradually grow,and the degree of Co oxidation significantly decreases.Consequently,the saturation magnetization increases from 0.13 to 0.43 T at the same Co content by increasing the substrate temperature from room temperature to 400℃.At a high substrate temperature,conductive pathways form among some of the clustered Co particles.Thus,resistivity rapidly declines from 1600 to 76μΩ·m.The magnetoresistive characteristic of Co−TiO2 films is achieved even at resistivity of as low as 76μΩ·m.These results reveal that the obtained nanocomposite films have low Co oxidation,high magnetization and magnetoresistance at room temperature.
