磁固相萃取(MSPE)是固相萃取(SPE)的一种,其使用的磁性吸附剂让萃取操作简便、耗时短、溶剂消耗少。在众多磁性吸附剂中,磁金属有机骨架(Magnetic Metal Organic Frameworks,M-MOFs)具有多样的拓扑结构、大比表面积和均匀可调节的孔结构...磁固相萃取(MSPE)是固相萃取(SPE)的一种,其使用的磁性吸附剂让萃取操作简便、耗时短、溶剂消耗少。在众多磁性吸附剂中,磁金属有机骨架(Magnetic Metal Organic Frameworks,M-MOFs)具有多样的拓扑结构、大比表面积和均匀可调节的孔结构,是近年来新型吸附材料的重要研究方向之一。M-MOFs已广泛应用于食品、环境、生物、医药等领域的样品前处理中,如重金属、多环芳烃、染料、添加剂、生物分子与药物的萃取分离。本文主要介绍了M-MOFs的结构组成,总结了其四种合成方法,概括了其在药物萃取分析中的应用,并在三个方面对其发展趋势进行了展望。展开更多
A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the b...A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the basic operational principle of the FSPMLM is introduced;and the magnetic fields at the two typical conditions of no-load are analyzed.Secondly,the FSPMLM is analyzed by the two-dimensional finite element method（FEM） to investigate the static electromagnetic characteristics such as flux-linkage,back EMF（electromotive force） and inductance performances.The cogging forces of two kinds of FSPMLMs with different shaped cores are analyzed and compared,and the results show that the cogging force is significantly reduced by using the E-shaped cores.Additionally,based on the co-energy method,the thrust equation is derived and verified by the simulation results obtained by the FEM.Finally,an experimental prototype is used to test the characteristics under open circuit and load conditions.The simulation and experimental results indicate that the proposed motor has advantages of a sinusoidal back-EMF waveform,a small cogging effect and a high thrust density,and it is suitable for the application of linear direct driving machine tools.展开更多
The organic gel-thermal reduction process was used for the preparation of ferromagnetic metal Ni, Co and Fe fine fibers from the raw materials of citric acid, lactic acid and metal salts. The structure, thermal decomp...The organic gel-thermal reduction process was used for the preparation of ferromagnetic metal Ni, Co and Fe fine fibers from the raw materials of citric acid, lactic acid and metal salts. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of these gel precursors were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermo-gravimetric/differential scanning calorimetry and scanning electron microscopy. The results show that spinnability of gel largely depends on molecular structure of metal-carboxylate complex that is a linear-type structure formed in the gel. As a result, the gels exhibit a good spinnability. Metal Ni, Co and Fe fine fibers are featured with diameters of around 1 μm and a high aspect ratio up to 1×106.展开更多
Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic propertie...Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic properties and how iron reduction would affect the magneticminerals in soils. Reduction associated with organic matter decomposition strongly affected soilmagnetic parameters at low pH. The losses of original soil magnetic signals in terms of magneticsusceptibility (X), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanentmagnetization (ARM) and saturation isothermal remanent magnetization (SIRM) at pH 4～6 during thetwo-month saturation treatment, were 66%～94%, 54%～90%, 64%～95% and 33%～83%, respectively. Thesechanges were interpreted as a consequence of substantial dissolution of maghaemite and haematite inthe soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stablesingle domain soil maghaemite grains were also sensitive to reduction, which suggested that bothpedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite,instead, was the most stable iron form under reducing conditions.展开更多
We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or s...We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions （hydrogen bonds, anion-Tr or lone- pair-~r interactions）, leading to low magnetic susceptibilities. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.展开更多
Conventional permanent magnet synchronous machine (PMSM) has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-...Conventional permanent magnet synchronous machine (PMSM) has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets (PMs) are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current i_d, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.展开更多
The full-potential linearized augmented plane wave (FPLAPW) method with the generalized gradient approximations (GGA) is applied to study the compound [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<...The full-potential linearized augmented plane wave (FPLAPW) method with the generalized gradient approximations (GGA) is applied to study the compound [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB> (NITmPy = 2 - (3' - Pyridy1) -4, 4, 5, 5 - tetramethylimidazolin - 1 - oxy1 - 3 - oxide). The total density of states (DOS) and the partial density of states (pDOS) are calculated to explain the electronic and the magnetic properties of [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB>. It is found that [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB> is stable in the ferromagnetic state and the magnetic moment of the molecule mainly comes from the Cu atoms (0.518 μ<SUB>B</SUB>) with partial contribution from N, O atoms of nitronyl nitroxide radicals. There exist orbital hybridization between 3d orbital of Cu and p orbitals of N(1) (from pyridyl rings of the NITmPy ligands) and N(4) (from azido group) and the weak direct exchange interactions between Cu and O atoms of nitronyl nitroxides. In addition, the bridging carbon atom (C(6)) carries a significant negative spin density (-0.019 μ<SUB>B</SUB>). The sign alternation of the magnetic moment along zthe pyridyl ring is obtained, which agrees with experiments.展开更多
In the design of the motor used for electric vehicles(EVS),vibration and noise problems are often ignored,which reduce the reliability and service life of the motor.In this paper,an interior permanent magnet synchrono...In the design of the motor used for electric vehicles(EVS),vibration and noise problems are often ignored,which reduce the reliability and service life of the motor.In this paper,an interior permanent magnet synchronous motor(IPMSM)with high power density is taken as an example,and its electromagnetic vibration and noise problem is investigated and optimized.Firstly,the factors that generate the electromagnetic force harmonic of IPMSM are analyzed by theoretical derivation.Furthermore,the mode and electromagnetic harmonic distribution of the motor are calculated and analyzed by establishing the electromagnetic-structure-sound coupling simulation model.Then,by combining finite element method(FEM)with modern optimization algorithm,an electromagnetic vibration and noise performance optimization method is proposed in the electromagnetic design stage of the motor.Finally,an IPMSM is optimized by this method for electromagnetic vibration and noise performance.The results of comparison between before and after optimization prove the feasibility of the method.展开更多
The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiat...The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiation from the sun and energy radioactive isotopes.展开更多
The authors discovered a new magnetic properties of the phosphorous and carbon with a four and five bond, and stibine, bismuthine in organometallic chemistry. This allows to modify many of classical reactions by repla...The authors discovered a new magnetic properties of the phosphorous and carbon with a four and five bond, and stibine, bismuthine in organometallic chemistry. This allows to modify many of classical reactions by replacing with the nitrogen atoms to atoms of phosphorus, arsenic, antimony and bismuth. The authors have proposed a new mechanism for the possible reactions.展开更多
文摘磁固相萃取(MSPE)是固相萃取(SPE)的一种,其使用的磁性吸附剂让萃取操作简便、耗时短、溶剂消耗少。在众多磁性吸附剂中,磁金属有机骨架(Magnetic Metal Organic Frameworks,M-MOFs)具有多样的拓扑结构、大比表面积和均匀可调节的孔结构,是近年来新型吸附材料的重要研究方向之一。M-MOFs已广泛应用于食品、环境、生物、医药等领域的样品前处理中,如重金属、多环芳烃、染料、添加剂、生物分子与药物的萃取分离。本文主要介绍了M-MOFs的结构组成,总结了其四种合成方法,概括了其在药物萃取分析中的应用,并在三个方面对其发展趋势进行了展望。
文摘A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the basic operational principle of the FSPMLM is introduced;and the magnetic fields at the two typical conditions of no-load are analyzed.Secondly,the FSPMLM is analyzed by the two-dimensional finite element method（FEM） to investigate the static electromagnetic characteristics such as flux-linkage,back EMF（electromotive force） and inductance performances.The cogging forces of two kinds of FSPMLMs with different shaped cores are analyzed and compared,and the results show that the cogging force is significantly reduced by using the E-shaped cores.Additionally,based on the co-energy method,the thrust equation is derived and verified by the simulation results obtained by the FEM.Finally,an experimental prototype is used to test the characteristics under open circuit and load conditions.The simulation and experimental results indicate that the proposed motor has advantages of a sinusoidal back-EMF waveform,a small cogging effect and a high thrust density,and it is suitable for the application of linear direct driving machine tools.
基金Projects(50474038 50674048) supported by the National Natural Science Foundation of China
文摘The organic gel-thermal reduction process was used for the preparation of ferromagnetic metal Ni, Co and Fe fine fibers from the raw materials of citric acid, lactic acid and metal salts. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of these gel precursors were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermo-gravimetric/differential scanning calorimetry and scanning electron microscopy. The results show that spinnability of gel largely depends on molecular structure of metal-carboxylate complex that is a linear-type structure formed in the gel. As a result, the gels exhibit a good spinnability. Metal Ni, Co and Fe fine fibers are featured with diameters of around 1 μm and a high aspect ratio up to 1×106.
文摘Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic properties and how iron reduction would affect the magneticminerals in soils. Reduction associated with organic matter decomposition strongly affected soilmagnetic parameters at low pH. The losses of original soil magnetic signals in terms of magneticsusceptibility (X), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanentmagnetization (ARM) and saturation isothermal remanent magnetization (SIRM) at pH 4～6 during thetwo-month saturation treatment, were 66%～94%, 54%～90%, 64%～95% and 33%～83%, respectively. Thesechanges were interpreted as a consequence of substantial dissolution of maghaemite and haematite inthe soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stablesingle domain soil maghaemite grains were also sensitive to reduction, which suggested that bothpedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite,instead, was the most stable iron form under reducing conditions.
基金This work was supported by the National Natural Science Foundation of China （No.21172210）.
文摘We herein report two crystals based on 2-（imidazo[1,2-a]pyridin-2-yl）-2-oxoacetic acid rad- ical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions （hydrogen bonds, anion-Tr or lone- pair-~r interactions）, leading to low magnetic susceptibilities. 2-（imidazo[1,2-a]pyridin-2-yl）- 2-oxoaeetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional double- stranded chain structure assembled through double hydrogen bonds and anion-To interactions, and reveals weak ferromagnetism.
基金Supported by Natural Science Foundation of China(No.50677042).
文摘Conventional permanent magnet synchronous machine (PMSM) has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets (PMs) are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current i_d, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.
文摘The full-potential linearized augmented plane wave (FPLAPW) method with the generalized gradient approximations (GGA) is applied to study the compound [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB> (NITmPy = 2 - (3' - Pyridy1) -4, 4, 5, 5 - tetramethylimidazolin - 1 - oxy1 - 3 - oxide). The total density of states (DOS) and the partial density of states (pDOS) are calculated to explain the electronic and the magnetic properties of [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB>. It is found that [Cu(NTTmPy)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>2</SUB>]<SUB>n</SUB> is stable in the ferromagnetic state and the magnetic moment of the molecule mainly comes from the Cu atoms (0.518 μ<SUB>B</SUB>) with partial contribution from N, O atoms of nitronyl nitroxide radicals. There exist orbital hybridization between 3d orbital of Cu and p orbitals of N(1) (from pyridyl rings of the NITmPy ligands) and N(4) (from azido group) and the weak direct exchange interactions between Cu and O atoms of nitronyl nitroxides. In addition, the bridging carbon atom (C(6)) carries a significant negative spin density (-0.019 μ<SUB>B</SUB>). The sign alternation of the magnetic moment along zthe pyridyl ring is obtained, which agrees with experiments.
基金This work was supported by the Fundamental Research Funds for the Central Universities(No.2019YJS181).
文摘In the design of the motor used for electric vehicles(EVS),vibration and noise problems are often ignored,which reduce the reliability and service life of the motor.In this paper,an interior permanent magnet synchronous motor(IPMSM)with high power density is taken as an example,and its electromagnetic vibration and noise problem is investigated and optimized.Firstly,the factors that generate the electromagnetic force harmonic of IPMSM are analyzed by theoretical derivation.Furthermore,the mode and electromagnetic harmonic distribution of the motor are calculated and analyzed by establishing the electromagnetic-structure-sound coupling simulation model.Then,by combining finite element method(FEM)with modern optimization algorithm,an electromagnetic vibration and noise performance optimization method is proposed in the electromagnetic design stage of the motor.Finally,an IPMSM is optimized by this method for electromagnetic vibration and noise performance.The results of comparison between before and after optimization prove the feasibility of the method.
文摘The authors have proposed a new of magnetic isotope theory of life on Earth. According to this theory the initial impetus for the beginning of the synthesis of organic compounds is the impact of electromagnetic radiation from the sun and energy radioactive isotopes.
文摘The authors discovered a new magnetic properties of the phosphorous and carbon with a four and five bond, and stibine, bismuthine in organometallic chemistry. This allows to modify many of classical reactions by replacing with the nitrogen atoms to atoms of phosphorus, arsenic, antimony and bismuth. The authors have proposed a new mechanism for the possible reactions.
