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Magnetic Field Curves and Magnetic Equipotential Surfaces around Crossing Electrical Wires Replacing Classical Magnetic Field Lines
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作者 Geoffroy Auvert 《Open Journal of Applied Sciences》 2024年第8期1996-2008,共13页
This article is based on a recent model specifically defining magnetic field values around electrical wires. With this model, calculations of field around parallel wires were obtained. Now, this model is extended with... This article is based on a recent model specifically defining magnetic field values around electrical wires. With this model, calculations of field around parallel wires were obtained. Now, this model is extended with the new concept of magnetic equipotential surface to magnetic field curves around crossing wires. Cases of single, double, and triple wires are described. Subsequent article will be conducted for more general scenarios where wires are neither infinite nor parallel. 展开更多
关键词 magnetic Field Value magnetic Field Vector magnetic Field Line magnetic Field Curve Equipotential Surface Crossing Electrical Wires magnetic Cross Product
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Preliminary geological interpretation of long-wavelength magnetic anomalies over China and surrounding regions
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作者 Jie Wang YanYan Yang +4 位作者 ZhiMa Zeren Jian Wang Xin Wang YuXin Luo XuHui Shen 《Earth and Planetary Physics》 EI CAS CSCD 2024年第3期445-458,共14页
Long-wavelength(>500 km)magnetic anomalies originating in the lithosphere were first found in satellite magnetic surveys.Compared to the striking magnetic anomalies around the world,the long-wavelength magnetic ano... Long-wavelength(>500 km)magnetic anomalies originating in the lithosphere were first found in satellite magnetic surveys.Compared to the striking magnetic anomalies around the world,the long-wavelength magnetic anomalies in China and surrounding regions are relatively weak.Specialized research on each of these anomalies has been quite inadequate;their geological origins remain unclear,in particular their connection to tectonic activity in the Chinese and surrounding regions.We focus on six magnetic high anomalies over the(1)Tarim Basin,(2)Sichuan Basin(3)Great Xing’an Range,(4)Barmer Basin,(5)Central Myanmar Basin,and(6)Sunda and Banda Arcs,and a striking magnetic low anomaly along the southern part of the Himalayan-Tibetan Plateau.We have analyzed their geological origins by reviewing related research and by detailed comparison with geological results.The tectonic backgrounds for these anomalies belong to two cases:either ancient basin basement,or subduction-collision zone.However,the geological origins of large-scale regional magnetic anomalies are always subject to dispute,mainly because of limited surface exposure of sources,later tectonic destruction,and superposition of multi-phase events. 展开更多
关键词 long-wavelength magnetic anomaly lithospheric magnetic anomaly lithospheric magnetic field model satellite magnetic survey CSES
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The Magnetic Longitudinal (P-) Wave’s Propagation and Energy Models Underlying the Mechanisms of Its Capacity to Absorb Free Energy
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作者 Jianzhong Jiang Yufeng Wang 《Journal of Power and Energy Engineering》 2024年第7期39-62,共24页
The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagn... The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagnetic (LEM) waves. The revised Maxwell’s equations include the crucial parameters being the attenuation time constants of magnetic vortex potential and electric vortex potential generated by external electromagnetic field within the propagation medium. Specific expressions for them are obtained through theoretical analysis. Subsequently, a model for propagating magnetic P-wave generated by the superposition of a left-handed photo and a right-handed photon in a vacuum is formulated based on reevaluated total current law and revised Faraday’s law, covering wave equations, energy equation, as well as propagation mode involving mutual induction and conversion between scalar magnetic field and vortex electric field. Furthermore, through theoretical derivations centered around magnetic P-wave, evidence was presented regarding its ability to absorb huge free energy through the entangled interaction between zero-point vacuum energy field and the torsion field produced by the vortex electric field. 展开更多
关键词 QED (Quantum Electrodynamics) Energy Wave and TEM (Transverse Electromagnetic) Wave magnetic P-Wave Modified Faraday’s Law of Electromagnetic Induction Electric/magnetic Vortex Potential Zero-Point Vacuum Energy
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Contribution of glial cells to the neuroprotective effects triggered by repetitive magnetic stimulation:a systematic review 被引量:1
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作者 Susana A.Ferreira Nuno Pinto +2 位作者 Inês Serrenho Maria Vaz Pato Graça Baltazar 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第1期116-123,共8页
Repetitive transcranial magnetic stimulation has been increasingly studied in different neurological diseases,and although most studies focus on its effects on neuronal cells,the contribution of nonneuronal cells to t... Repetitive transcranial magnetic stimulation has been increasingly studied in different neurological diseases,and although most studies focus on its effects on neuronal cells,the contribution of nonneuronal cells to the improvement trigge red by repetitive transcranial magnetic stimulation in these diseases has been increasingly suggested.To systematically review the effects of repetitive magnetic stimulation on non-neuronal cells two online databases.Web of Science and PubMed were searched fo r the effects of high-frequency-repetitive transcranial magnetic stimulation,low-frequencyrepetitive transcranial magnetic stimulation,intermittent theta-bu rst stimulation,continuous thetaburst stimulation,or repetitive magnetic stimulation on non-neuronal cells in models of disease and in unlesioned animals or cells.A total of 52 studies were included.The protocol more frequently used was high-frequency-repetitive magnetic stimulation,and in models of disease,most studies report that high-frequency-repetitive magnetic stimulation led to a decrease in astrocyte and mic roglial reactivity,a decrease in the release of pro-inflammatory cyto kines,and an increase of oligodendrocyte proliferation.The trend towards decreased microglial and astrocyte reactivity as well as increased oligodendrocyte proliferation occurred with intermittent theta-burst stimulation and continuous theta-burst stimulation.Few papers analyzed the low-frequency-repetitive transcranial magnetic stimulation protocol,and the parameters evaluated were restricted to the study of astrocyte reactivity and release of pro-inflammatory cytokines,repo rting the absence of effects on these paramete rs.In what concerns the use of magnetic stimulation in unlesioned animals or cells,most articles on all four types of stimulation reported a lack of effects.It is also important to point out that the studies were developed mostly in male rodents,not evaluating possible diffe rential effects of repetitive transcranial magnetic stimulation between sexes.This systematic review supports that thro ugh modulation of glial cells repetitive magnetic stimulation contributes to the neuroprotection or repair in various neurological disease models.Howeve r,it should be noted that there are still few articles focusing on the impact of repetitive magnetic stimulation on non-neuronal cells and most studies did not perform in-depth analyses of the effects,emphasizing the need for more studies in this field. 展开更多
关键词 ASTROCYTE GLIA high-frequency repetitive magnetic stimulation inflammation low-frequency repetitive magnetic stimulation MICROGLIA neurologic disorders OLIGODENDROCYTE repetitive magnetic stimulation theta-burst stimulation
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Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere
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作者 JiaWei Gao ZhaoJin Rong +3 位作者 Qi Zhang Anna Mittelholz Chi Zhang Yong Wei 《Earth and Planetary Physics》 EI CAS CSCD 2024年第5期728-741,共14页
Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of ups... Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity(∣BIMF∣),solar wind dynamic pressure(PS W),solar extreme ultraviolet flux(EUV),and Martian seasons(L s).Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and PS W.Correlations observed with EUV flux and Ls were weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars perihelion.We find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣andPSWconditions.Our analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration depth.Those findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed now.Moreover,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field. 展开更多
关键词 Martian magnetic field external magnetic field upstream solar wind drivers IMF penetration altitude magnetic field activity indices
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MOFs‑Derived Strategy and Ternary Alloys Regulation in Flower‑Like Magnetic‑Carbon Microspheres with Broadband Electromagnetic Wave Absorption
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作者 Mengqiu Huang Bangxin Li +7 位作者 Yuetong Qian Lei Wang Huibin Zhang Chendi Yang Longjun Rao Gang Zhou Chongyun Liang Renchao Che 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第11期479-493,共15页
Broadband electromagnetic(EM)wave absorption materials play an important role in military stealth and health protection.Herein,metal–organic frameworks(MOFs)-derived magnetic-carbon CoNiM@C(M=Cu,Zn,Fe,Mn)microspheres... Broadband electromagnetic(EM)wave absorption materials play an important role in military stealth and health protection.Herein,metal–organic frameworks(MOFs)-derived magnetic-carbon CoNiM@C(M=Cu,Zn,Fe,Mn)microspheres are fabricated,which exhibit flower-like nano–microstructure with tunable EM response capacity.Based on the MOFs-derived CoNi@C microsphere,the adjacent third element is introduced into magnetic CoNi alloy to enhance EM wave absorption performance.In term of broadband absorption,the order of efficient absorption bandwidth(EAB)value is Mn>Fe=Zn>Cu in the CoNiM@C microspheres.Therefore,MOFs-derived flower-like CoNiMn@C microspheres hold outstanding broadband absorption and the EAB can reach up to 5.8 GHz(covering 12.2–18 GHz at 2.0 mm thickness).Besides,off-axis electron holography and computational simulations are applied to elucidate the inherent dielectric dissipation and magnetic loss.Rich heterointerfaces in CoNiMn@C promote the aggregation of the negative/positive charges at the contacting region,forming interfacial polarization.The graphitized carbon layer catalyzed by the magnetic CoNiMn core offered the electron mobility path,boosting the conductive loss.Equally importantly,magnetic coupling is observed in the CoNiMn@C to strengthen the magnetic responding behaviors.This study provides a new guide to build broadband EM absorption by regulating the ternary magnetic alloy. 展开更多
关键词 magnetic-carbon microspheres MOFs derivatives Electromagnetic wave absorption magnetic loss Broadband absorption
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Treatment of anastomotic stricture after rectal cancer operation by magnetic compression technique:A case report
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作者 Miao-Miao Zhang Huan-Chen Sha +5 位作者 Hai-Rong Xue Yuan-Fa Qin Fang-Fang Dong Li Zhang Yi Lyu Xiao-Peng Yan 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第5期1443-1448,共6页
BACKGROUNDThe treatment of postoperative anastomotic stenosis(AS)after resection of colorectalcancer is challenging.Endoscopic balloon dilation is used to treat stenosisin such cases,but some patients do not show impr... BACKGROUNDThe treatment of postoperative anastomotic stenosis(AS)after resection of colorectalcancer is challenging.Endoscopic balloon dilation is used to treat stenosisin such cases,but some patients do not show improvement even after multipleballoon dilations.Magnetic compression technique(MCT)has been used for gastrointestinalanastomosis,but its use for the treatment of postoperative AS aftercolorectal cancer surgery has rarely been reported.CASE SUMMARYWe report a 72-year-old man who underwent radical resection of colorectal cancerand ileostomy one year ago.An ileostomy closure was prepared six months ago,but colonoscopy revealed a narrowing of the rectal anastomosis.Endoscopic balloondilation was performed three times,but colonoscopy showed no significantimprovement in stenosis.The AS was successfully treated using MCT.CONCLUSIONMCT is a minimally invasive method that can be used for the treatment of postoperativeAS after colorectal cancer surgery. 展开更多
关键词 Rectostenosis magnetic surgery magnetic Surgery Clinic Rectal cancer magnetic compression technique Case report
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Recent geomagnetic storms observed by Macao Science Satellite-1
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作者 Qing Yan HongBo Yao 《Earth and Planetary Physics》 EI CAS CSCD 2024年第4期565-569,共5页
Geomagnetic storms are rapid disturbances of the Earth’s magnetosphere.They are related to many geophysical phenomena and have large influences on human activities.Observing and studying geomagnetic storms is thus of... Geomagnetic storms are rapid disturbances of the Earth’s magnetosphere.They are related to many geophysical phenomena and have large influences on human activities.Observing and studying geomagnetic storms is thus of great significance to both scientific research and geomagnetic hazards prevention.The Macao Science Satellite-1(MSS-1)project includes two high-precision Chinese geomagnetic satellites successfully launched on May 21,2023.The main purpose of MSS-1 is to accurately measure the Earth’s magnetic field.Here,we analyze early MSS-1 geomagnetic field measurements and report observations of two recent geomagnetic storms that occurred on March 24,2024 and May 11,2024.We also calculate the related geoelectric fields as an initial step towards a quantitative assessment of geomagnetic hazards. 展开更多
关键词 Macao Science Satellite-1 geomagnetic storms satellite magnetics electromagnetic induction geoelectric fields
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Diffusion Equations of the Electric Charges and Magnetic Flux
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作者 Salama Abdelhady Mohamed S. Abdelhady 《Journal of Electromagnetic Analysis and Applications》 2024年第5期69-83,共15页
Innovative definitions of the electric and magnetic diffusivities through conducting mediums and innovative diffusion equations of the electric charges and magnetic flux are verified in this article. Such innovations ... Innovative definitions of the electric and magnetic diffusivities through conducting mediums and innovative diffusion equations of the electric charges and magnetic flux are verified in this article. Such innovations depend on the analogy of the governing laws of diffusion of the thermal, electrical, and magnetic energies and newly defined natures of the electric charges and magnetic flux as energy, or as electromagnetic waves, that have electric and magnetic potentials. The introduced diffusion equations of the electric charges and magnetic flux involve Laplacian operator and the introduced diffusivities. Both equations are applied to determine the electric and magnetic fields in conductors as the heat diffusion equation which is applied to determine the thermal field in steady and unsteady heat diffusion conditions. The use of electric networks for experimental modeling of thermal networks represents sufficient proof of similarity of the diffusion equations of both fields. By analysis of the diffusion phenomena of the three considered modes of energy transfer;the rates of flow of these energies are found to be directly proportional to the gradient of their volumetric concentration, or density, and the proportionality constants in such relations are the diffusivity of each energy. Such analysis leads also to find proportionality relations between the potentials of such energies and their volumetric concentrations. Validity of the introduced diffusion equations is verified by correspondence their solutions to the measurement results of the electric and magnetic fields in microwave ovens. 展开更多
关键词 Diffusion Coefficient Diffusion Equation Electric Charge magnetic Flux Electromagnetic Waves Electric Field magnetic Field
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Laboratory observation of electron energy distribution near three-dimensional magnetic nulls 被引量:1
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作者 何任川 徐田超 +7 位作者 杨肖易 肖池阶 张祖煜 袁瑞鑫 王晓钢 郭志彬 余修铭 盖跃 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第3期46-52,共7页
The acceleration of electrons near three-dimensional(3D)magnetic nulls is crucial to the energy conversion mechanism in the 3D magnetic reconnection process.To explore electron acceleration in a 3D magnetic null topol... The acceleration of electrons near three-dimensional(3D)magnetic nulls is crucial to the energy conversion mechanism in the 3D magnetic reconnection process.To explore electron acceleration in a 3D magnetic null topology,we constructed a pair of 3D magnetic nulls in the PKU Plasma Test(PPT)device and observed acceleration of electrons near magnetic nulls.This study measured the plasma floating potential and ion density profiles around the 3D magnetic null.The potential wells near nulls may be related to the energy variations of electrons,so we measured the electron distribution functions(EDFs)at different spatial positions.The axial variation of EDF shows that the electrons deviate from the Maxwell distribution near magnetic nulls.With scanning probes that can directionally measure and theoretically analyze based on curve fitting,the variations of EDFs are linked to the changes of plasma potential under 3D magnetic null topology.The kinetic energy of electrons accelerated by the electric field is 6 eV(v_(e)~7v_(Alfvén-e))and the scale of the region where accelerating electrons exist is in the order of serval electron skin depths. 展开更多
关键词 electron acceleration EEDF 3D magnetic null magnetic reconnection
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Staging liver fibrosis with various diffusion-weighted magnetic resonance imaging models 被引量:1
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作者 Yan-Li Jiang Juan Li +6 位作者 Peng-Fei Zhang Feng-Xian Fan Jie Zou Pin Yang Peng-Fei Wang Shao-Yu Wang Jing Zhang 《World Journal of Gastroenterology》 SCIE CAS 2024年第9期1164-1176,共13页
BACKGROUND Diffusion-weighted imaging(DWI)has been developed to stage liver fibrosis.However,its diagnostic performance is inconsistent among studies.Therefore,it is worth studying the diagnostic value of various diff... BACKGROUND Diffusion-weighted imaging(DWI)has been developed to stage liver fibrosis.However,its diagnostic performance is inconsistent among studies.Therefore,it is worth studying the diagnostic value of various diffusion models for liver fibrosis in one cohort.AIM To evaluate the clinical potential of six diffusion-weighted models in liver fibrosis staging and compare their diagnostic performances.METHODS This prospective study enrolled 59 patients suspected of liver disease and scheduled for liver biopsy and 17 healthy participants.All participants underwent multi-b value DWI.The main DWI-derived parameters included Mono-apparent diffusion coefficient(ADC)from mono-exponential DWI,intravoxel incoherent motion model-derived true diffusion coefficient(IVIM-D),diffusion kurtosis imaging-derived apparent diffusivity(DKI-MD),stretched exponential model-derived distributed diffusion coefficient(SEM-DDC),fractional order calculus(FROC)model-derived diffusion coefficient(FROC-D)and FROC model-derived microstructural quantity(FROC-μ),and continuous-time random-walk(CTRW)model-derived anomalous diffusion coefficient(CTRW-D)and CTRW model-derived temporal diffusion heterogeneity index(CTRW-α).The correlations between DWI-derived parameters and fibrosis stages and the parameters’diagnostic efficacy in detecting significant fibrosis(SF)were assessed and compared.RESULTS CTRW-D(r=-0.356),CTRW-α(r=-0.297),DKI-MD(r=-0.297),FROC-D(r=-0.350),FROC-μ(r=-0.321),IVIM-D(r=-0.251),Mono-ADC(r=-0.362),and SEM-DDC(r=-0.263)were significantly correlated with fibrosis stages.The areas under the ROC curves(AUCs)of the combined index of the six models for distinguishing SF(0.697-0.747)were higher than each of the parameters alone(0.524-0.719).The DWI models’ability to detect SF was similar.The combined index of CTRW model parameters had the highest AUC(0.747).CONCLUSION The DWI models were similarly valuable in distinguishing SF in patients with liver disease.The combined index of CTRW parameters had the highest AUC. 展开更多
关键词 Liver fibrosis magnetic resonance imaging Diffusion-weighted magnetic resonance Liver biopsy Significant fibrosis
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Simulation of the SMILE Soft X-ray Imager response to a southward interplanetary magnetic field turning 被引量:1
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作者 Andrey Samsonov Graziella Branduardi-Raymont +3 位作者 Steven Sembay Andrew Read David Sibeck Lutz Rastaetter 《Earth and Planetary Physics》 EI CSCD 2024年第1期39-46,共8页
The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magne... The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magnetic field turning and produce SXI count maps with a 5-minute integration time.By making assumptions about the magnetopause shape,we find the magnetopause standoff distance from the count maps and compare it with the one obtained directly from the magnetohydrodynamic(MHD)simulation.The root mean square deviations between the reconstructed and MHD standoff distances do not exceed 0.2 RE(Earth radius)and the maximal difference equals 0.24 RE during the 25-minute interval around the southward turning. 展开更多
关键词 MAGNETOPAUSE magnetic reconnection solar wind charge exchange southward interplanetary magnetic field numerical modeling Solar wind Magnetosphere Ionosphere Link Explorer(SMILE) Soft X-ray Imager
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Magnetic and magnetocaloric effect of Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass
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作者 于世霖 田路 +4 位作者 王俊峰 赵新国 李达 莫兆军 李昺 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期602-606,共5页
Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity(RC)was reported.Er_(20)Ho_(20)Dy_(20)Cu_... Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity(RC)was reported.Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass was observed with typical spin glass behavior around 15.5 K.In addition,we find that the magnetic entropy change(-△S_(M))originates from the sample undergoing a ferromagnetic(FM)to paramagnetic(PM)transition around 20 K.Under a field change from 0 T to 7 T,the value of maximum magnetic entropy change(-△S_(M)^(max))reaches 12.5 J/kg·K,and the corresponding value of RC reaches 487.7 J/kg in the temperature range from 6 K to 60 K.The large RC and wide temperature range make the Er_(20)Ho_(20)Dy_(20)Cu_(20)Ni_(20)high-entropy metallic glass be a promising material for application in magnetic refrigerators. 展开更多
关键词 magnetic materials magnetocaloric effect high-entropy metallic glass magnetic refrigeration large refrigeration capacity
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Modeling and Validation of Diamagnetic Rotor Levitated by Permanent Magnetics
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作者 Yuanping Xu Yue Zhang +1 位作者 Jin Zhou Chaowu Jin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第3期224-235,共12页
As an innovative,low-power consuming,and low-stiffness suspension approach,the diamagnetic levitation technique has attracted considerable interest because of its potential applicability in miniaturized mechanical sys... As an innovative,low-power consuming,and low-stiffness suspension approach,the diamagnetic levitation technique has attracted considerable interest because of its potential applicability in miniaturized mechanical systems.The foundation of a diamagnetic levitation system is mathematical modeling,which is essential for operating performance optimization and stability prediction.However,few studies on systematic mathematical modeling have been reported.In this study,a systematic mathematical model for a disc-shaped diamagnetically levitated rotor on a permanent magnet array is proposed.Based on the proposed model,the magnetic field distribution characteristics,diamagnetic levitation force characteristics(i.e.,levitation height and stiffness),and optimized theoretical conditions for realizing stable levitation are determined.Experiments are conducted to verify the feasibility of the proposed mathematical model.Theoretical predictions and experimental results indicate that increasing the levitation height enlarges the stable region.Moreover,with a further increase in the rotor radius,the stable regions of the rotor gradually diminish and even vanish.Thus,when the levitation height is fixed,a moderate rotor radius permits stable levitation.This study proposes a mathematical modeling method for a diamagnetic levitation system that has potential applications in miniaturized mechanical systems. 展开更多
关键词 Diamagnetic levitation magnetic levitation ROTOR MODELING VALIDATION STABILITY
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Simulation of magnetization process and Faraday effect of magnetic bilayer films
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作者 Sheng Gao An Du +2 位作者 Lei Zhang Tian-Guang Li Da-Cheng Ma 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期590-597,共8页
We described ferromagnetic film and bilayer films composed of two ferromagnetic layers coupled through antiferromagnetic interfacial interaction by classical Heisenberg model and simulated their magnetization state,ma... We described ferromagnetic film and bilayer films composed of two ferromagnetic layers coupled through antiferromagnetic interfacial interaction by classical Heisenberg model and simulated their magnetization state,magnetic permeability,and Faraday effect at zero and finite temperature by using the Landau–Lifshitz–Gilbert(LLG)equation.The results indicate that in a microwave field with positive circular polarization,the ferromagnetic film has one resonance peak while the bilayer film has two resonance peaks.However,the resonance peak disappears in ferromagnetic film,and only one resonance peak emerges in bilayer film in the negative circularly polarized microwave field.When the microwave field’s frequency exceeds the film’s resonance frequency,the Faraday rotation angle of the ferromagnetic film is the greatest,and it decreases when the thickness of the two halves of the bilayer is reduced.When the microwave field’s frequency remains constant,the Faraday rotation angle fluctuates with temperature in the same manner as spontaneous magnetization does.When a DC magnetic field is applied in the direction of the anisotropic axis of the film,the Faraday rotation angle varies with the DC magnetic field and shows a similar shape of the hysteresis loop. 展开更多
关键词 magnetic bilayer films magnetic permeability hysteresis loop Faraday effect Landau-Lifshitz-Gilbert(LLG)equation
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The Effect of External Magnetic Field on Electron Scale Kelvin–Helmholtz Instability
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作者 D.Tsiklauri 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第9期236-247,共12页
We use particle-in-cell,fully electromagnetic,plasma kinetic simulation to study the effect of external magnetic field on electron scale Kelvin–Helmholtz instability(ESKHI).The results are applicable to collisionless... We use particle-in-cell,fully electromagnetic,plasma kinetic simulation to study the effect of external magnetic field on electron scale Kelvin–Helmholtz instability(ESKHI).The results are applicable to collisionless plasmas when,e.g.,solar wind interacts with planetary magnetospheres or a magnetic field is generated in AGN jets.We find that as in the case of magnetohydrodynamic(MHD)KHI,in the kinetic regime,the presence of an external magnetic field reduces the growth rate of the instability.In the MHD case,there is a known threshold magnetic field for KHI stabilization,while for ESKHI this is to be analytically determined.Without a kinetic analytical expression,we use several numerical simulation runs to establish an empirical dependence of ESKHI growth rate,Γ(B_(0))ω_(pe),on the strength of the applied external magnetic field.We find the best fit is hyperbolic,Γ(B_(0))ω_(pe)=Γ_(0)ω_(pe)/(A+BB_(0)),where Γ_(0) is the ESKHI growth rate without an external magnetic field and B_(0)=B_(0)/B_(MHD)is the ratio of external and two-fluid MHD stability threshold magnetic field,derived here.An analytical theory to back up this growth rate dependence on the external magnetic field is needed.The results suggest that in astrophysical settings where a strong magnetic field pre-exists,the generation of an additional magnetic field by the ESKHI is suppressed,which implies that nature provides a“safety valve”—natural protection not to“over-generate”magnetic field by the ESKHI mechanism.Remarkably,we find that our two-fluid MHD threshold magnetic field is the same(up to a factor √γ_(0))as the DC saturation magnetic field,previously predicted by fully kinetic theory. 展开更多
关键词 INSTABILITIES magnetic fields PLASMAS Sun:heliosphere ISM:magnetic fields
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Optimization of tracheoesophageal fistula model established with Tshaped magnet system based on magnetic compression technique
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作者 Miao-Miao Zhang Jian-Qi Mao +5 位作者 Lin-Xin Shen Ai-Hua Shi Xin Lyu Jia Ma Yi Lyu Xiao-Peng Yan 《World Journal of Gastroenterology》 SCIE CAS 2024年第16期2272-2280,共9页
BACKGROUND The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula(TEF),but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model ... BACKGROUND The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula(TEF),but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model control.We designed a Tshaped magnet system to overcome these problems and verified its effectiveness via animal experiments.AIM To investigate the effectiveness of a T-shaped magnet system for establishing a TEF model in beagle dogs.METHODS Twelve beagles were randomly assigned to groups in which magnets of the Tshaped scheme(study group,n=6)or normal magnets(control group,n=6)were implanted into the trachea and esophagus separately under gastroscopy.Operation time,operation success rate,and accidental injury were recorded.After operation,the presence and timing of cough and the time of magnet shedding were observed.Dogs in the control group were euthanized after X-ray and gastroscopy to confirm establishment of TEFs after coughing,and gross specimens of TEFs were obtained.Dogs in the study group were euthanized after X-ray and gastroscopy 2 wk after surgery,and gross specimens were obtained.Fistula size was measured in all animals,and then harvested fistula specimens were examined by hematoxylin and eosin(HE)and Masson trichrome staining.RESULTS The operation success rate was 100%for both groups.Operation time did not differ between the study group(5.25 min±1.29 min)and the control group(4.75 min±1.70 min;P=0.331).No bleeding,perforation,or unplanned magnet attraction occurred in any animal during the operation.In the early postoperative period,all dogs ate freely and were generally in good condition.Dogs in the control group had severe cough after drinking water at 6-9 d after surgery.X-ray indicated that the magnets had entered the stomach,and gastroscopy showed TEF formation.Gross specimens of TEFs from the control group showed the formation of fistulas with a diameter of 4.94 mm±1.29 mm(range,3.52-6.56 mm).HE and Masson trichrome staining showed scar tissue formation and hierarchical structural disorder at the fistulas.Dogs in the study group did not exhibit obvious coughing after surgery.X-ray examination 2 wk after surgery indicated fixed magnet positioning,and gastroscopy showed no change in magnet positioning.The magnets were removed using a snare under endoscopy,and TEF was observed.Gross specimens showed well-formed fistulas with a diameter of 6.11 mm±0.16 mm(range,5.92-6.36 mm),which exceeded that in the control group(P<0.001).Scar formation was observed on the internal surface of fistulas by HE and Masson trichrome staining,and the structure was more regular than that in the control group.CONCLUSION Use of the modified T-shaped magnet scheme is safe and feasible for establishing TEF and can achieve a more stable and uniform fistula size compared with ordinary magnets.Most importantly,this model offers better controllability,which improves the flexibility of follow-up studies. 展开更多
关键词 magnetic surgery magnetic compression technique Tracheoesophageal fistula MAGNET Animal model Beagles
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Enhanced magnetic anisotropy and high hole mobility in magnetic semiconductor Ga_(1-x-y)Fe_(x)Ni_(y)Sb
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作者 Zhi Deng Hailong Wang +5 位作者 Qiqi Wei Lei Liu Hongli Sun Dong Pan Dahai Wei Jianhua Zhao 《Journal of Semiconductors》 EI CAS CSCD 2024年第1期16-21,共6页
(Ga,Fe)Sb is a promising magnetic semiconductor(MS)for spintronic applications because its Curie temperature(T_(C))is above 300 K when the Fe concentration is higher than 20%.However,the anisotropy constant Ku of(Ga,F... (Ga,Fe)Sb is a promising magnetic semiconductor(MS)for spintronic applications because its Curie temperature(T_(C))is above 300 K when the Fe concentration is higher than 20%.However,the anisotropy constant Ku of(Ga,Fe)Sb is below 7.6×10^(3)erg/cm^(3)when Fe concentration is lower than 30%,which is one order of magnitude lower than that of(Ga,Mn)As.To address this issue,we grew Ga_(1-x-y)Fe_(x)Ni_(y)Sb films with almost the same x(≈24%)and different y to characterize their magnetic and electrical transport properties.We found that the magnetic anisotropy of Ga_(0.76-y)Fe_(0.24)Ni_(y)Sb can be enhanced by increasing y,in which Ku is negligible at y=1.7%but increases to 3.8×10^(5)erg/cm^(3)at y=6.1%(T_(C)=354 K).In addition,the hole mobility(μ)of Ga_(1-x-y)Fe_(x)Ni_(y)Sb reaches 31.3 cm^(2)/(V∙s)at x=23.7%,y=1.7%(T_(C)=319 K),which is much higher than the mobility of Ga_(1-x)Fe_(x)Sb at x=25.2%(μ=6.2 cm^(2)/(V∙s)).Our results provide useful information for enhancing the magnetic anisotropy and hole mobility of(Ga,Fe)Sb by using Ni co-doping. 展开更多
关键词 magnetic semiconductor molecular beam epitaxy Fe-Ni co-doping magnetic anisotropy hole mobility
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Structural control of magnetic nanoparticles for positive nuclear magnetic resonance imaging
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作者 Zulaikha Ali Yunfei Zhang +5 位作者 Michael GKaul Billy Truong Deepika Bhanot Gerhard Adam Yuan-Yuan Li He Wei 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第10期17-28,共12页
In addition to the tens of millions of medical doses consumed annually around the world,a vast number of nuclear magnetic resonance imaging(MRI)contrast agents are being deployed in MRI research and development,offeri... In addition to the tens of millions of medical doses consumed annually around the world,a vast number of nuclear magnetic resonance imaging(MRI)contrast agents are being deployed in MRI research and development,offering precise diagnostic information,targeting capabilities,and analyte sensing.Superparamagnetic iron oxide nanoparticles(SPIONs)are notable among these agents,providing effective and versatile MRI applications while also being heavy-metal-free,bioconjugatable,and theranostic.We designed and implemented a novel two-pronged computational and experimental strategy to meet the demand for the efficient and rigorous development of SPION-based MRI agents.Our MATLAB-based modeling simulation and magnetic characterization revealed that extremely small maghemite SPIONs in the 1-3 nm range possess significantly reduced transversal relaxation rates(R_(2))and are therefore preferred for positive(T_(1)-weighted)MRI.Moreover,X-ray diffraction and X-ray absorption fine structure analyses demonstrated that the diffraction pattern and radial distribution function of our SPIONs matched those of the targeted maghemite crystals.In addition,simulations of the X-ray near-edge structure spectra indicated that our synthesized SPIONs,even at 1 nm,maintained a spherical structure.Furthermore,in vitro and in vivo MRI investigations showed that our 1-nm SPIONs effectively highlighted whole-body blood vessels and major organs in mice and could be cleared through the kidney route to minimize potential post-imaging side effects.Overall,our innovative approach enabled a swift discovery of the desired SPION structure,followed by targeted synthesis,synchrotron radiation spectroscopic studies,and MRI evaluations.The efficient and rigorous development of our high-performance SPIONs can set the stage for a computational and experimental platform for the development of future MRI agents. 展开更多
关键词 magnetic nanoparticles Structure control Nuclear magnetic resonance imaging Modeling simulation X-ray absorption fine structure
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Probing the peripheral self-generated magnetic field distribution in laser-plasma magnetic reconnection with Martin-Puplett interferometer polarimeter
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作者 张雅芃 姚嘉文 +2 位作者 刘正东 马作霖 仲佳勇 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期129-134,共6页
Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Pup... Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Puplett interferometer(MPI)polarimeter to probe the peripheral magnetic fields generated in the common magnetic reconnection configuration,two separated coplanar plane targets,in laser-target interaction.We introduce a new method that can obtain polarization information from the interference pattern instead of the sinusoidal function fitting of the intensity.A bidirectional magnetic field is observed from the side view,which is consistent with the magneto-hydro-dynamical(MHD)simulation results of self-generated magnetic field reconnection.We find that the cancellation of reverse magnetic fields after averaging and integration along the observing direction could reduce the magnetic field strength by one to two orders of magnitude.It indicates that imaging resolution can significantly affect the accuracy of measured magnetic field strength. 展开更多
关键词 laser-plasma experiment POLARIMETER self-generated magnetic field magnetic reconnection
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