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Second harmonic magnetoacoustic responses of magnetic nanoparticles in magnetoacoustic tomography with magnetic induction 认领
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作者 郭各朴 高雅 +3 位作者 李禹志 马青玉 屠娟 章东 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第3期259-264,共6页
Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The l... Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications. 展开更多
关键词 magnetoacoustic TOMOGRAPHY with MAGNETIC INDUCTION second HARMONIC magnetoacoustic RESPONSES MAGNETIC nanoparticles MAGNETIC force mechanical OSCILLATIONS
文章速递Magnetic metal organic framework for pre-concentration of ampicillin from cow milk samples 认领
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作者 Ahmad Reza Bagheri Mehrorang Ghaedi 《药物分析学报:英文版》 SCIE CAS CSCD 2020年第4期365-375,共11页
The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework(MMOF)and subsequently its application as sorbent for ultrasound assisted magne... The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework(MMOF)and subsequently its application as sorbent for ultrasound assisted magnetic solid phase extraction(UAMSPE)of ampicillin(AMP)from cow milk samples prior to high performance liquid chromatography-Ultraviolet(HPLC-UV)determination.Characteristics of prepared MMOF were fully investigated by different techniques which showed the exclusive properties of proposed sorbent in terms of proper functionality,desirable magnetic property and also high specific surface area.Different influential factors on extraction recovery including sorbent dosage,ultrasonic time,washing solvent volume and eluent solvent volume were assessed using central composite design(CCD)based response surface methodology(RSM)as an operative and powerful optimization tool.This is the first report for determination of AMP using MMOF.The proposed method addressed some drawbacks of other methods and sorbents for determination of AMP.The presented method decreases the extraction time(4 min)and also enhances adsorption capacity(250 mg/g).Moreover,the magnetic property of presented sorbent(15 emu/g)accelerates the extraction process which does not need filtration,centrifuge and precipitation procedures.Under the optimized conditions,the proposed method is applicable for linear range of 1.0-5000.0 μg/L with detection limit of 0.29 μg/L,satisfactory recoveries(≥95.0%)and acceptable repeatability(RSD less than 4.0%).The present study indicates highly promising perspectives of MMOF for highly effective analysis of AMP in complicated matrices. 展开更多
关键词 Magnetic metal organic framework Ultrasound assisted magnetic solid phase extraction Ampicillin Cow milk samples
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Direct laser interference patterning of nonvolatile magnetic nanostructures in Fe60Al40 alloy via disorder‐induced ferromagnetism 认领
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作者 Philipp Graus Thomas BM?ller +2 位作者 Paul Leiderer Johannes Boneberg Nikolay I.Polushkin 《光电进展(英文)》 2020年第1期1-7,共7页
Current magnetic memories are based on writing and reading out the domains with opposite orientation of the magnetization vector.Alternatively,information can be encoded in regions with a different value of the satura... Current magnetic memories are based on writing and reading out the domains with opposite orientation of the magnetization vector.Alternatively,information can be encoded in regions with a different value of the saturation magnetization.The latter approach can be realized in principle with chemical order-disorder transitions in intermetallic alloys.Here,we study such transformations in a thin-film(35 nm)Fe60Al40 alloy and demonstrate the formation of periodic magnetic nanostructures(PMNS)on its surface by direct laser interference patterning(DLIP).These PMNS are nonvolatile and detectable by magnetic force microscopy(MFM)at room temperature after DLIP with a single nanosecond pulse.We provide different arguments that the PMNS we observe originate from increasing magnetization in maxima of the interference pattern because of chemical disordering in the atomic lattice of the alloy at temperatures T higher than the critical temperature Tc for the order(B2)-disorder(A2)transition.Theoretically,our simulations of the temporal evolution of a partially ordered state at T>Tc reveal that the disordering rate is significant even below the melting threshold.Experimentally,we find that the PMNS are erasable with standard thermal annealing at T<Tc. 展开更多
关键词 thin films laser PATTERNING MAGNETIC DOTS MAGNETIC memory
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Mechanism of ferromagnetism in(Fe,Co)-codoped 4H-SiC from density functional theory 认领
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作者 Bing Zhang Jing-Tao Huang +2 位作者 Long Lin Yong-Hao Xu Hua-Long Tao 《理论物理通讯:英文版》 SCIE CAS CSCD 2020年第5期78-84,共7页
First-principles calculations are performed to investigate the electronic structures and magnetic properties of(Fe,Co)-codoped 4H-SiC using the generalized gradient approximation plus Hubbard U method.We find that 4H-... First-principles calculations are performed to investigate the electronic structures and magnetic properties of(Fe,Co)-codoped 4H-SiC using the generalized gradient approximation plus Hubbard U method.We find that 4H-SiC doped with an isolated Fe atom and an isolated Co atom produces a total magnetic moment of 5.98μB and 6.00μB respectively.We estimate TC of about 263.1 K for the(Fe,Co)-codoped 4H-SiC system.We study ferromagnetic and antiferromagnetic coupling in(Fe,Co)-codoped 4H-SiC.Ferromagnetic behavior is observed.The strong ferromagnetic couplings between local magnetic moments can be attributed to p–d hybridization between Fe,Co and neighboring C.However,the(Fe,Co,V(Si))-codoped 4H-SiC system shows antiferromagnetic coupling when an Si vacancy is introduced in the same 4H-SiC supercell.The results may be helpful for further study on transition metal-codoped systems. 展开更多
关键词 rst principles dilute magnetic semiconductors electronic structures magnetic properties 4H-SIC
Structure,magnetism and magnetic thermal properties of heavy rare earth Tb1-xTmxFeO3(x=0.00,0.15,0.25) polycrystalline samples 认领
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作者 Xiang Jin Jianjun Zhao +6 位作者 Hongwei Chen Fengze Cao Li Cheng Taichao Su Wenxing Wang Jia Liu Yi Lu 《稀土学报:英文版》 SCIE EI CAS CSCD 2020年第6期600-605,共6页
Tb1-xTmxFeO3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is p... Tb1-xTmxFeO3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is pbnm.When the Tm3+doping amount increases,the characteristics of the spin-flip of the sample decreases following an initial increase at the beginning;the antiferromagnetic property almost reaches zero;the magnetization decreases at the beginning but increases later on.The maximum magnetic entropy change and magnetic refrigeration effect RCP are reduced at varying degrees.Under a 7 T magnetic field,the maximum magnetic entropy change,△Smax,for the three samples of Tb1-xTmxFeO3 with x=0.00,0.15,0.25 is 13.78,-9.28,and 10.69 J/(K·kg),respectively;the magnetic refrigeration capacity(RCP) is 316.85,175.2,and 297.60 J/kg,respectively.In summary,doping with the element Tm reduces △Smax and RCP of the sample.Since the maximum magnetic entropy change and the cooling capacity for the three samples are relatively large,they can be used as an alternative for magnetic refrigerants. 展开更多
关键词 SPIN-FLIP Magnetic entropy change Magnetic refrigeration capacity MAGNETISM Rare earths
High voltage-controlled magnetic anisotropy and interface magnetoelectric effect in sputtered multilayers annealed at high temperatures 认领
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作者 LeZhi Wang Xiang Li +8 位作者 Taisuke Sasaki Kin Wong GuoQiang Yu ShouZhong Peng Chao Zhao Tadakatsu Ohkubo Kazuhiro Hono WeiSheng Zhao KangLong Wang 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS CSCD 2020年第7期114-119,共6页
Voltage control of magnetism promises great energy efficiency in writing magnetic memory. Here, using Cr/Mo/CoFeB/MgO multilayers stable under high annealing temperatures up to 590°C, we significantly enhance the... Voltage control of magnetism promises great energy efficiency in writing magnetic memory. Here, using Cr/Mo/CoFeB/MgO multilayers stable under high annealing temperatures up to 590°C, we significantly enhance the interfacial crystallinity, thereby the interface-originated perpendicular magnetic anisotropy(PMA), voltage-controlled magnetic anisotropy(VCMA), and interface magnetoelectric(ME) effect. High interfacial PMA of 1.35 mJ/m~2, VCMA coefficient of-138 fJ/(V m), and interface ME coefficient, which is 2-3 orders of magnitude larger than ab initio calculation results are simultaneously achieved after annealing at 500°C. These promising results enabled by the industry-applicable sputtering process will pave the way for highdensity voltage-controlled spintronic devices. 展开更多
关键词 voltage-controlled magnetic anisotropy(VCMA) magnetoelectric(ME)effect perpendicular magnetic anisotropy
Optimization of iron and aluminum recovery in bauxite 认领
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作者 Qian Long Jun-qi Li +2 位作者 Chao-yi Chen Yuan-pei Lan Guo-ling Wei 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2020年第3期310-318,共9页
Recovering iron and aluminum efficiently is the key route to utilize low-grade high-iron bauxite.Aiming to optimize the iron separating process and elevate both Fe and Al recovery ratio,three different Fe-Al recovery ... Recovering iron and aluminum efficiently is the key route to utilize low-grade high-iron bauxite.Aiming to optimize the iron separating process and elevate both Fe and Al recovery ratio,three different Fe-Al recovery processes with different magnetic roasting(R),Bayer leaching process(L)and magnetic separation(S)orders were investigated.The studied processes include bauxite leaching→red mud roasting→magnetic separation(L-R-S),bauxite roasting→magnetic separation→leaching(R-S-L)and bauxite roasting→leaching→magnetic separation(R-L-S).The iron recovery ratio,Fe2O3 content in iron concentration and the bauxite dissolution ratio of each process were investigated.Moreover,the optimizations of the leaching,roasting and magnetic separation conditions were studied.Results indicate that the R-S-L process should be an advisable order to recover both alumina and iron.In the three processes,the R-S-L route had the highest alumina dissolution ratio and iron recovery ratio,which was 86.20%and 69.58%,respectively,while the Fe2O3 content of the iron concentrate was 40.66%. 展开更多
关键词 High-iron BAUXITE MAGNETIC ROASTING MAGNETIC separation RECOVERY RATIO Dissolution RATIO
Hybrid Reduced Graphene Oxide with Special Magnetoresistance for Wireless Magnetic Field Sensor 认领
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作者 Songlin Yang Mingyan Tan +3 位作者 Tianqi Yu Xu Li Xianbin Wang Jin Zhang 《纳微快报:英文版》 SCIE EI CAS CSCD 2020年第5期177-190,共14页
Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation... Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society. 展开更多
关键词 Large MAGNETORESISTANCE MAGNETIC NANOCRYSTALS REDUCED graphene OXIDE WIRELESS MAGNETIC field sensor
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Development of high-performance dry-pressed anisotropic permanent ferrite for La-Ca-Sr-Co system 认领
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作者 Dai-Man Zhu Zhao-Wen Geng +5 位作者 Rong-Ming Liu Xiao-Wen Zhou Li-Ying Jia Guo-Hui Hu Qian Wang Bing-Shan Li 《稀有金属:英文版》 SCIE EI CAS CSCD 2020年第1期89-94,共6页
In this work,the BMS-12 pre-sintered material was used as the basic material,and the optimal secondary additive addition amount was found by the wet pressing process.Then,the anisotropic ferrite material was prepared ... In this work,the BMS-12 pre-sintered material was used as the basic material,and the optimal secondary additive addition amount was found by the wet pressing process.Then,the anisotropic ferrite material was prepared by dry-pres sing method,and the effects of camphor adhesives,calcium stearate lubricant and powder particle size on the magnetic properties were studied.The experimental results show that the appropriate addition amount of camphor adhesive and calcium stearate lubricant is 0.6 wt%and 0.8 wt%,respectively.High remanence and coercivity can be obtained for particle size of 0.85-1.00μm.Superior dry-pressed magnet ferrite was prepared with typical properties of magnetic induction intensity of Br=421 mT,induction coercivity of Hcb=296 kA·m-1,intrinsic coercivity of Hcj=369 kA·m-1 and maximum energy product of(BH)max=33.3 kJ·m-3,which have reached the level of TDK corporation product of FB5 D.This shows that the dry-pressed magnet of La-Ca-Sr-Co system has higher remanence and intrinsic coercivity than the traditional wetpressed Sr-ferrite. 展开更多
关键词 Dry-press MOLDING Permanent MAGNETIC FERRITE La-Ca-Sr-Co SYSTEM MAGNETIC properties
Could non-invasive brain-stimulation prevent neuronal degeneration upon ion channel re-distribution and ion accumulation after demyelination? 认领
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作者 Friederike Pfeiffer Alia Benali 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第11期1977-1980,共4页
Fast and efficient transmission of electrical signals in the nervous system is mediated through myelinated nerve fibers.In neuronal diseases such as multiple sclerosis,the conduction properties of axons are disturbed ... Fast and efficient transmission of electrical signals in the nervous system is mediated through myelinated nerve fibers.In neuronal diseases such as multiple sclerosis,the conduction properties of axons are disturbed by the removal of the myelin sheath,leaving nerve cells at a higher risk of degenerating.In some cases,the protective myelin sheath of axons can be rebuilt by remyelination through oligodendroglial cells.In any case,however,changes in the ion channel organization occur and may help to restore impulse conduction after demyelination.On the other hand,changes in ion channel distribution may increase the energy demand of axons,thereby increasing the probability of axonal degeneration.Many attempts have been made or discussed in recent years to increase remyelination of affected axons in demyelinating diseases such as multiple sclerosis.These approaches range from pharmacological treatments that reduce inflammatory processes or block ion channels to the modulation of neuronal activity through electrical cortical stimulation.However,these treatments either affect the entire organism(pharmacological)or exert a very local effect(electrodes).Current results show that neuronal activity is a strong regulator of oligodendroglial development.To bridge the gap between global and very local treatments,non-invasive transcranial magnetic stimulation could be considered.Transcranial magnetic stimulation is externally applied to brain areas and experiments with repetitive transcranial magnetic stimulation show that the neuronal activity can be modulated depending on the stimulation parameters in both humans and animals.In this review,we discuss the possibilities of influencing ion channel distribution and increasing neuronal activity by transcranial magnetic stimulation as well as the effect of this modulation on oligodendroglial cells and their capacity to remyelinate previously demyelinated axons.Although the physiological mechanisms underlying the effects of transcranial magnetic stimulation clearly need further inv 展开更多
关键词 ion channel multiple sclerosis neuronal activity OLIGODENDROCYTE (re-)myelination repetitive TRANSCRANIAL MAGNETIC STIMULATION TRANSCRANIAL MAGNETIC STIMULATION
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Ferrimagnetic m PEG-b-PHEP copolymer micelles loaded with iron oxide nanocubes and emodin for enhanced magnetic hyperthermia–chemotherapy 认领
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作者 Yonghong Song Dongdong Li +8 位作者 Yang Lu Kun Jiang Yi Yang Yunjun Xu Liang Dong Xu Yan Daishun Ling Xianzhu Yang Shu-Hong Yu 《国家科学评论:英文版》 SCIE EI CSCD 2020年第4期723-736,共14页
As a non-invasive therapeutic method without penetration-depth limitation,magnetic hyperthermia therapy(MHT)under alternating magnetic field(AMF)is a clinically promising thermal therapy.However,the poor heating conve... As a non-invasive therapeutic method without penetration-depth limitation,magnetic hyperthermia therapy(MHT)under alternating magnetic field(AMF)is a clinically promising thermal therapy.However,the poor heating conversion efficiency and lack of stimulus–response obstruct the clinical application of magnetofluid-mediated MHT.Here,we develop a ferrimagnetic polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane)(m PEG-b-PHEP)copolymer micelle loaded with hydrophobic iron oxide nanocubes and emodin(denoted as EMM).Besides an enhanced magnetic resonance(MR)contrast ability(r2=271 m M^-1 s^-1)due to the high magnetization,the specific absorption rate(2518 W/g at 35 k A/m)and intrinsic loss power(6.5 n Hm2/kg)of EMM are dozens of times higher than the clinically available iron oxide nanoagents(Feridex and Resovist),indicating the high heating conversion efficiency.Furthermore,this composite micelle with a flowable core exhibits a rapid response to magnetic hyperthermia,leading to an AMF-activated supersensitive drug release.With the high magnetic response,thermal sensitivity and magnetic targeting,this supersensitive ferrimagnetic nanocomposite realizes an above 70%tumor cell killing effect at an extremely low dosage(10μg Fe/m L),and the tumors on mice are completely eliminated after the combined MHT–chemotherapy. 展开更多
关键词 MAGNETIC hypertherm ia therapy sensitive thermal response CHEM otherapy MAGNETIC targeting THERANOSTICS
Progress of intravoxel incoherent motion diffusion-weighted imaging in liver diseases 认领
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作者 Yun-Yun Tao Yi Zhou +5 位作者 Ran Wang Xue-Qin Gong Jing Zheng Cui Yang Lin Yang Xiao-Ming Zhang 《世界临床病例杂志》 SCIE 2020年第15期3164-3176,共13页
Traditional magnetic resonance(MR)diffusion-weighted imaging(DWI)uses a single exponential model to obtain the apparent diffusion coefficient to quantitatively reflect the diffusion motion of water molecules in living... Traditional magnetic resonance(MR)diffusion-weighted imaging(DWI)uses a single exponential model to obtain the apparent diffusion coefficient to quantitatively reflect the diffusion motion of water molecules in living tissues,but it is affected by blood perfusion.Intravoxel incoherent motion(IVIM)-DWI utilizes a double-exponential model to obtain information on pure water molecule diffusion and microcirculatory perfusion-related diffusion,which compensates for the insufficiency of traditional DWI.In recent years,research on the application of IVIM-DWI in the diagnosis and treatment of hepatic diseases has gradually increased and has achieved considerable progress.This study mainly reviews the basic principles of IVIM-DWI and related research progress in the diagnosis and treatment of hepatic diseases. 展开更多
关键词 Magnetic resonance imaging Diffusion magnetic resonance imaging Liver diseases Liver cirrhosis CARCINOMA CHOLANGIOCARCINOMA
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Method of Relaxation Rates Measurement in Proton-Containing Materials 认领
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作者 Sergey Ermak Vladimir Semenov Roman Lozov 《电子科技学刊:英文版》 CAS CSCD 2020年第1期10-18,共9页
A method of the relaxation time measurement in a flowing sample, based on the comparison of the amplitudes of nuclear magnetic resonance(NMR) signals observed from the reference and tested flowing samples was represen... A method of the relaxation time measurement in a flowing sample, based on the comparison of the amplitudes of nuclear magnetic resonance(NMR) signals observed from the reference and tested flowing samples was represented. The inductive and optical methods of NMR signal detection in the flowing sample were compared.The levels of NMR signal(10000 Hz-1/2) and the Hanle magnetometers signal-to-noise ratio(3500 Hz-1/2) were calculated and the possibility of the NMR signal detection with the small-size Hanle magnetometer was demonstrated. Additionally, the absence of a magnet-analyzer and the ability to measure both longitudinal and transverse relaxation time with high accuracy was demonstrated. 展开更多
关键词 Hanle effect MAGNETIC field nuclear MAGNETIC resonance(NMR) quantum MAGNETOMETER RELAXATION time
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磁性氧化石墨烯/聚苯胺纳米复合材料的制备及再生循环吸附性研究 认领
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作者 王彦娜 夏爱清 +1 位作者 梁慧锋 李铭远 《化学研究与应用》 CAS CSCD 北大核心 2020年第7期1296-1301,共6页
由氧化法和原位合成法成功制备了磁性氧化石墨烯/聚苯胺(Fe3O4/GO/PANI,MPGO)纳米复合材料,使用X射线衍射、热重分析、红外光谱、VSM、BET等对所得材料进行了结构表征和性能测试,研究了复合材料对甲基橙染料的吸附性能。结果表明:pH为4... 由氧化法和原位合成法成功制备了磁性氧化石墨烯/聚苯胺(Fe3O4/GO/PANI,MPGO)纳米复合材料,使用X射线衍射、热重分析、红外光谱、VSM、BET等对所得材料进行了结构表征和性能测试,研究了复合材料对甲基橙染料的吸附性能。结果表明:pH为4时,MPGO吸附量最大,为198 mg·g-1;450 min达到吸附平衡,吸附量为211.08 mg·g-1。MPGO对甲基橙的吸附行为符合Langmuir等温模型和准二级动力学模型;经过7次再生循环后,MPGO对甲基橙的吸附量保持为初始吸附量的72.2%,具有较好的重复利用性。 展开更多
关键词 磁性 氧化石墨烯 聚苯胺 吸附 磁分离
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In-situ observation of magnetization reversal process of Sm(Co,Cu,Fe,Zr)_z magnets with different Fe contents 认领
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作者 Shuo Wu Dong-Tao Zhang +4 位作者 Ming Yue Yun-Qiao Wang Zhi-Feng Shang Dan Wu Jing-Ming Liang 《稀有金属:英文版》 SCIE EI CAS CSCD 2020年第3期250-255,共6页
Sm(Co,Cu,Fe,Zr)z magnets have drawn much attention for high-temperature applications due to their high Curie temperature,strong corrosion resistance and thermal stability.The effect of increasing Fe content on the dis... Sm(Co,Cu,Fe,Zr)z magnets have drawn much attention for high-temperature applications due to their high Curie temperature,strong corrosion resistance and thermal stability.The effect of increasing Fe content on the distribution of elements and squareness(Sr)of demagnetization curves were investigated for two kinds of magnets with different nominal compositions of Sm(CobalFe0.15-Cu0.07Zr0.03)7.8 and Sm(CobalFe0.28Cu0.07Zr0.03)6.6 in this work.The magnetic properties of the magnets with higher Fe content fluctuate greatly after different solution treatments,indicating that they are more sensitive to the process temperature.The increase in Fe content can obviously enhance the cellular phase size.Meanwhile,inhomogeneous Cu distribution is observed in the Sm(CobalFe0.28-Cu0.07Zr0.03)6.6 magnet,resulting in the different cellular structures and corresponding magnetic domain patterns in different regions in the inner grains.Furthermore,the lower Cu content regions are responsible for the wider magnetic domain,which have weaker resistance to applied magnetic field.As a result,Sr of demagnetization curve decreases with the increase in Fe content due to the inhomogeneous Cu distribution,which was confirmed by in-situ observation of electron probe micro-analyzer(EPMA)and magneto-optical Kerr optical microscope(MOKE). 展开更多
关键词 Sm(Co Cu Fe Zr)_z MAGNETS CU distribution Microstructure MAGNETIC properties MAGNETIC domain Squareness
Magnetoacoustic position imaging for liquid metal in animal interstitial structure 认领
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作者 赵筱赫 刘国强 +1 位作者 夏慧 李艳红 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第5期346-353,共8页
Magnetoacoustic tomography with magnetic induction(MAT-MI),as a new kind of in-vivo imaging method,has potential application value in interstitial fluid research.In this paper,we propose the application of MAT-MI with... Magnetoacoustic tomography with magnetic induction(MAT-MI),as a new kind of in-vivo imaging method,has potential application value in interstitial fluid research.In this paper,we propose the application of MAT-MI with liquid metal serving as a tracer of the interstitial structure to study its fluid behavior,and use it to implement the positional imaging of the spatial distribution of liquid metal.Owing to the particularity of liquid metal magnetoacoustic pressure(MAP)signals,we propose an envelope analysis method to extract the rising edge of the amplitude envelope of the detected waveform as effective position data.And for the first time,we propose the method of superpositing pixel matrix to achieve the position imaging of liquid metal.Finally,the positional imaging of the liquid metal sample embedded in the gel is achieved to have relatively accurate results.This study provides a method of effectively extracting data and implementing the position imaging for liquid metal in the interstitial structure in the frame of MAT-MI. 展开更多
关键词 magnetic acoustic tomography with magnetic induction(MAT-MI) liquid metal interstitial structure position imaging
Giant low-field magnetocaloric effect in EuTi(1-x)NbxO3(x = 0.05, 0.1, 0.15, and 0.2) compounds 认领
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作者 姜文昊 莫兆军 +5 位作者 罗佳薇 郑哲轩 卢秋杰 刘国栋 沈俊 李岚 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第3期396-401,共6页
The magnetic properties and magnetocaloric effect(MCE)of EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds are investigated.Owing to electronic doping,parts of Ti ions are replaced by Nb ions,the lattice constant incre... The magnetic properties and magnetocaloric effect(MCE)of EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds are investigated.Owing to electronic doping,parts of Ti ions are replaced by Nb ions,the lattice constant increases and a small number of Ti~(4+)(3d~0)ions change into Ti~(3+)(3d~1).It is the ferromagnetism state that is dominant in the derivative balance.The values of the maximum magnetic entropy change(-?SM~(max))are 10.3 J/kg·K,9.6 J/kg·K,13.1 J/kg·K,and 11.9 J/kg·K for EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds and the values of refrigeration capacity are 36,33,86,and 80 J/kg as magnetic field changes in a range of 0 T–1 T.The EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds with giant reversible MCE are considered as a good candidate for magnetic refrigerant working at lowtemperature and low-field. 展开更多
关键词 MAGNETOCALORIC effect MAGNETIC ENTROPY change MAGNETIC phase transformation
Perspective and Prospects for Rare Earth Permanent Magnets 认领
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作者 J.M.D.Coey 《工程(英文)》 SCIE EI 2020年第2期119-131,共13页
Rare earth permanent magnets constitute a mature technology,but the shock of the 2011 rare earth crisis led to the re-evaluation of many ideas from the 1980s and 1990s about possible new hard magnets containing little... Rare earth permanent magnets constitute a mature technology,but the shock of the 2011 rare earth crisis led to the re-evaluation of many ideas from the 1980s and 1990s about possible new hard magnets containing little or no rare earth(or heavy rare earth).Nd-Fe-B magnets have been painstakingly and skillfully optimized for a wide range of applications in which high performance is required at reasonable cost.Sm-Co is the material of choice when high-temperature stability is required,and Sm-Fe-N magnets are making their way into some niche applications.The scope for improvement in these basic materials by substitution has been rather thoroughly explored,and the effects of processing techniques on the microstructure and hysteresis are largely understood.A big idea from a generation ago-which held real potential to raise the record energy product significantly-was the oriented exchange-spring hard/soft nanocomposite magnet;however,it has proved very difficult to realize.Nevertheless,the field has evolved,and innovation has flourished in other areas.For example,electrical personal transport has progressed from millions of electric bicycles to the point where cars and trucks with electrical drives are becoming mainstream,and looks ready to bring the dominance of the internal combustion engine to an end.As the limitations of particular permanent magnets become clearer,ingenuity and imagination are being used to design around them,and to exploit the available mix of rare earth resources most efficiently.Huge new markets in robotics beckon,and the opportunities offered by additive manufacturing are just beginning to be explored.New methods of increasing magnet stability at elevated temperature are being developed,and integrated multifunctionality of hard magnets with other useful properties is now envisaged.These themes are elaborated here,with various examples. 展开更多
关键词 Rare earth MAGNETS MAGNETIC ANISOTROPY COERCIVITY Energy product MAGNETIC composites ADDITIVE manufacturing
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Self-magnetic-attracted NixFe(1-x)@NixFe(1-x)O nanoparticles on nickel foam as highly active and stable electrocatalysts towards alkaline oxygen evolution reaction 认领
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作者 Zuobo Yang Xin Liang 《纳米研究:英文版》 SCIE EI CAS CSCD 2020年第2期461-466,共6页
A facile self-magnetic-attracted approach was developed for highly active and stable NixFe(1-x)@NixFe(1-x)O/NF electrocatalysts towards alkaline oxygen evolution reaction.Firstly,a low-cost and scalable synthesis meth... A facile self-magnetic-attracted approach was developed for highly active and stable NixFe(1-x)@NixFe(1-x)O/NF electrocatalysts towards alkaline oxygen evolution reaction.Firstly,a low-cost and scalable synthesis method was developed to synthesis 4-5 nm hydrophilic NixFe(1-x)@NixFe(1-x)O core-shell nanocrystals with superparamagnetism.Then,these NixFe(1-x)@NixFe(1-x)O nanoparticles(NPs)could be easily supported on nickel foam without any binders or additives.Optimized by the composition effect,the Ni0.7Fe0.3@Ni0.7Fe0.3O/NF exhibits excellent activity for oxygen evolution reaction(OER),requires only 215 mV at 10 mA·cm^-2 and 260 mV at 100 mA-cm-2,with a Tafel slope of 47.4 mV·dec^-1 in 1.0 M KOH.Moreover,the underlying mechanism was carefully studied by X-ray diffraction(XRD),Raman,X-ray photoelectron spectroscopy(XPS)and X-ray absorption near-edge spectra(XANES)analysis and density functional theory(DFT)calculations.Due to the self-magnetic attraction,the catalyst shows outstanding stability throughout the electrocatalysis,surpassing than most self-supported catalysts.This work provides a new strategy for the construction of highly active and stable OER electrocatalysts,the nearly monodisperse magnetic NixFe(1-x)@NixFe(1-x)O NPs also serve an ideal building block for fundamental research of nickel-iron based catalyst. 展开更多
关键词 nearly monodisperse magnetic nanoparticles self-magnetic-attracted approach oxygen evolution reaction
Small interplanetary magnetic flux rope 认领
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作者 FENG HengQiang ZHAO GuoQing WANG JieMin 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2020年第2期183-194,共12页
Small interplanetary magnetic flux ropes(SIMFRs) are often detected by space satellites in the interplanetary space near 1 AU.These ropes can be fitted by a cylindrically symmetric magnetic model. The durations of SIM... Small interplanetary magnetic flux ropes(SIMFRs) are often detected by space satellites in the interplanetary space near 1 AU.These ropes can be fitted by a cylindrically symmetric magnetic model. The durations of SIMFRs are usually <12 h, and the diameters of SIMFRs are <0.20 AU and show power law distribution. Most SIMFRs are observed in the typically slow solar wind(<500 km/s), and only several events are observed with high speed(>700 km/s). Some SIMFRs demonstrate abnormal heavy ion compositions, such as abnormally high He abundance, abnormally high average iron ionization, and enhanced O7+abundance. These SIMFRs originate from remarkably hot coronal origins. Approximately 74.5% SIMFRs exhibit counterstreaming suprathermal electron signatures. Given their flux rope configuration, SIMFRs are potentially more effective for substorms. SIMFRs and magnetic clouds have many similar observational properties but also show some different observations.These similar properties may indicate that SIMFRs are the interplanetary counterparts of small coronal mass ejections. Some direct bodies of evidence have confirmed that several SIMFRs are interplanetary counterparts of CMEs. However, their different properties may imply that some SIMFRs have interplanetary origins. Therefore, one of the main aims of future research on SIMFRs is to determine whether SIMFRs originate from two different sources, that is, some events are formed in the solar coronal atmosphere, whereas others originate from the interplanetary space. Finally, in this paper, we offer some prospects that should be addressed in the future. 展开更多
关键词 MAGNETIC FLUX ropes MAGNETIC CLOUD CORONAL mass EJECTION heliospheric current sheet
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