Pub Date : 2023-02-09DOI: 10.1109/LMAG.2023.3243493
Kota Nomura;Masaomi Washino;Tetsuya Matsuda;Shun Tonooka;Seino Satoshi;H. Yoshida;K. Nishigaki;Takashi Nakagawa;Toshihiko Kiwa
Magnetic particle imaging (MPI) is an imaging modality that directly detects the nonlinear responses of magnetic nanoparticles (MNPs). Spatial encoding is achieved by saturating the magnetic moment of MNPs almost everywhere except in a special point called the field-free region in which a magnetic field vanishes. Recently, MPI sensitivity was improved using a field-free line (FFL) in which a field-free region was formed as a line. An MPI with an FFL device was developed using a neodymium magnet and an iron yoke to image objects with a small amount of MNPs, such as in biological systems. We have been developing MPI equipment for detecting amyloid-β, a causative agent of Alzheimer's disease. We attached amyloid-β probes to nanoparticles. In our development, we discriminated between magnetic particles that are bound to biological tissue from those that are suspended in the brain. We focused on the differences in relaxation times due to the change in the hydrodynamic diameter between the bound and unbound particles. Because the bound particles have a larger apparent particle size and do not rotate when an ac magnetic field is applied, the relaxation time is different from the unbound particles. Since the differences in the responses to the ac magnetic field appear as relaxation times, we investigated a particle-discrimination method using these differences and studied the magnetization response of MNPs using our developed MPI device.
{"title":"Magnetic-Particle-Discrimination Method Using Difference of Relaxation Time for Magnetic Particle Imaging","authors":"Kota Nomura;Masaomi Washino;Tetsuya Matsuda;Shun Tonooka;Seino Satoshi;H. Yoshida;K. Nishigaki;Takashi Nakagawa;Toshihiko Kiwa","doi":"10.1109/LMAG.2023.3243493","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3243493","url":null,"abstract":"Magnetic particle imaging (MPI) is an imaging modality that directly detects the nonlinear responses of magnetic nanoparticles (MNPs). Spatial encoding is achieved by saturating the magnetic moment of MNPs almost everywhere except in a special point called the field-free region in which a magnetic field vanishes. Recently, MPI sensitivity was improved using a field-free line (FFL) in which a field-free region was formed as a line. An MPI with an FFL device was developed using a neodymium magnet and an iron yoke to image objects with a small amount of MNPs, such as in biological systems. We have been developing MPI equipment for detecting amyloid-β, a causative agent of Alzheimer's disease. We attached amyloid-β probes to nanoparticles. In our development, we discriminated between magnetic particles that are bound to biological tissue from those that are suspended in the brain. We focused on the differences in relaxation times due to the change in the hydrodynamic diameter between the bound and unbound particles. Because the bound particles have a larger apparent particle size and do not rotate when an ac magnetic field is applied, the relaxation time is different from the unbound particles. Since the differences in the responses to the ac magnetic field appear as relaxation times, we investigated a particle-discrimination method using these differences and studied the magnetization response of MNPs using our developed MPI device.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanocrystalline soft magnets have attracted significant attention for their improvement of energy conversion devices. It has been considered that the partial nanocrystallization of amorphous structures is a key to macroscopic magnetic softness. However, the mechanism has not been clarified because of inadequate knowledge of the magnetic nanostructures connecting microscopic crystalline structures and macroscopic magnetic properties. Here, we performed small-angle neutron scattering (SANS) for Fe 85 Si 2 B 8 P 4 Cu 1 alloy ribbons (NANOMETs). Rapidly quenched ribbons were annealed at 375 °C and 400 °C for 5 min. The X-ray diffraction pattern for the as-quenched ribbons did not exhibit peaks. Therefore, their atomic structure can be considered amorphous. Oppositely, evident α-iron peaks were observed for the ribbons annealed at 375 °C and 400 °C. The nuclear scattering contribution in SANS indicates that the precipitations were formed with sizes in the nanoscale. The magnetic scattering contribution in SANS for the as-quenched ribbon, whose intensity decreased with an increase in the scattering vector q in proportion to q −4 , disappeared when magnetic fields were applied. This behavior is consistent with the conventional magnetic domain picture. Oppositely, the reduction rates of the magnetic scattering contribution for q were nonmonotonous for the nanocrystallized ribbons. Furthermore, strong magnetic scattering was observed in the directions inclined to the magnetic field. This feature is similar to that reported for Fe–(Nb, Zr)–B alloy ribbons (NANOPERMs). The knowledge on the magnetic nanostructures characterized by the unusual angular dependence of magnetic scattering would be helpful to considering the relationship between partially nanocrystallized structure and macroscopic soft magnetic properties.
{"title":"Magnetic Structural Analysis of Nanocrystalline Soft Magnets by Small-Angle Neutron Scattering","authors":"Hiroaki Mamiya;Yojiro Oba;Kosuke Hiroi;Takayuki Miyatake;Ravi Gautam;Hossein Sepehri-Amin;Tadakatsu Ohkubo","doi":"10.1109/LMAG.2023.3242108","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3242108","url":null,"abstract":"Nanocrystalline soft magnets have attracted significant attention for their improvement of energy conversion devices. It has been considered that the partial nanocrystallization of amorphous structures is a key to macroscopic magnetic softness. However, the mechanism has not been clarified because of inadequate knowledge of the magnetic nanostructures connecting microscopic crystalline structures and macroscopic magnetic properties. Here, we performed small-angle neutron scattering (SANS) for Fe\u0000<sub>85</sub>\u0000Si\u0000<sub>2</sub>\u0000B\u0000<sub>8</sub>\u0000P\u0000<sub>4</sub>\u0000Cu\u0000<sub>1</sub>\u0000 alloy ribbons (NANOMETs). Rapidly quenched ribbons were annealed at 375 °C and 400 °C for 5 min. The X-ray diffraction pattern for the as-quenched ribbons did not exhibit peaks. Therefore, their atomic structure can be considered amorphous. Oppositely, evident α-iron peaks were observed for the ribbons annealed at 375 °C and 400 °C. The nuclear scattering contribution in SANS indicates that the precipitations were formed with sizes in the nanoscale. The magnetic scattering contribution in SANS for the as-quenched ribbon, whose intensity decreased with an increase in the scattering vector \u0000<italic>q</i>\u0000 in proportion to \u0000<italic>q</i>\u0000<sup>−4</sup>\u0000, disappeared when magnetic fields were applied. This behavior is consistent with the conventional magnetic domain picture. Oppositely, the reduction rates of the magnetic scattering contribution for \u0000<italic>q</i>\u0000 were nonmonotonous for the nanocrystallized ribbons. Furthermore, strong magnetic scattering was observed in the directions inclined to the magnetic field. This feature is similar to that reported for Fe–(Nb, Zr)–B alloy ribbons (NANOPERMs). The knowledge on the magnetic nanostructures characterized by the unusual angular dependence of magnetic scattering would be helpful to considering the relationship between partially nanocrystallized structure and macroscopic soft magnetic properties.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This letter develops a reliable, integrated binary synapse and neuron model for hardware implementation of binary neural networks. Thanks to the nonvolatile nature of magnetic tunnel junctions and the unique features of carbon nanotube field-effect transistors, the modeled design does not require external memory to store weights and also consumes low static power. Also, due to the circuit structure, which did not use sequential parts, the developed circuit is immune to soft error. Because, in binary neural networks, weights are limited to two values of −1 and 1, the occurrence of soft errors dramatically reduces the accuracy of the network. Simulation results indicate that the design in this work consumes at least 9% lower power, occupies 34% lower area, and offers a 49% lower power delay area product. Also, Monte Carlo simulations have been performed to study the effect of the process variation on the network. The result of the Monte Carlo simulations shows that the proposed neuron has no logical error in 10 000 simulations. Consequently, the accuracy of the network utilization by the neuron is equal to the software-implemented network and does not decrease even in the presence of process variations.
{"title":"Hybrid MTJ/CNTFET-Based Binary Synapse and Neuron for Process-in-Memory Architecture","authors":"Milad Tanavardi Nasab;Arefe Amirany;Mohammad Hossein Moaiyeri;Kian Jafari","doi":"10.1109/LMAG.2023.3238271","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3238271","url":null,"abstract":"This letter develops a reliable, integrated binary synapse and neuron model for hardware implementation of binary neural networks. Thanks to the nonvolatile nature of magnetic tunnel junctions and the unique features of carbon nanotube field-effect transistors, the modeled design does not require external memory to store weights and also consumes low static power. Also, due to the circuit structure, which did not use sequential parts, the developed circuit is immune to soft error. Because, in binary neural networks, weights are limited to two values of −1 and 1, the occurrence of soft errors dramatically reduces the accuracy of the network. Simulation results indicate that the design in this work consumes at least 9% lower power, occupies 34% lower area, and offers a 49% lower power delay area product. Also, Monte Carlo simulations have been performed to study the effect of the process variation on the network. The result of the Monte Carlo simulations shows that the proposed neuron has no logical error in 10 000 simulations. Consequently, the accuracy of the network utilization by the neuron is equal to the software-implemented network and does not decrease even in the presence of process variations.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-16DOI: 10.1109/LMAG.2023.3237384
Angelika S. Thalmayer;Kilian Götz;Samuel Zeising;Georg Fischer
In magnetic drug targeting, special magnetic nanoparticles that carry the anticancer drug are injected into the cardiovascular system in the vicinity of the tumor and are navigated into the tumor using a magnetic field. Many researchers optimize single magnets for this purpose; however, magnetic arrays that are placed parallel to the vessel in order to increase the impact time of the magnetic force on the particles are also discussed. To the best of the authors' knowledge, the improvement by the increased impact time has not been studied in detail so far and, thus, will be addressed in this work. In this context, an artificial exponential magnetic field that approximates the field of a Halbach array and acts as an upper limit consideration is applied to different impact lengths within a predefined magnetic domain. To compare the impact of the field parameters, the total magnetic energetic effort is kept constant as a reference for studying variations of impact length. The results reveal that a longer impact length increases the attraction performance enormously. However, for the same magnetic effort, a longer impact length with a lower magnetic field strength leads to the same attraction of the particles as a shorter one with higher field strengths. Since it is easier to generate lower field strengths, the usage of arrays to realize a longer impact length is preferable.
{"title":"Impact of Array Length on Particle Attraction in Magnetic Drug Targeting: Investigation Using an Exponential Approximation of the Magnetic Field","authors":"Angelika S. Thalmayer;Kilian Götz;Samuel Zeising;Georg Fischer","doi":"10.1109/LMAG.2023.3237384","DOIUrl":"https://doi.org/10.1109/LMAG.2023.3237384","url":null,"abstract":"In magnetic drug targeting, special magnetic nanoparticles that carry the anticancer drug are injected into the cardiovascular system in the vicinity of the tumor and are navigated into the tumor using a magnetic field. Many researchers optimize single magnets for this purpose; however, magnetic arrays that are placed parallel to the vessel in order to increase the impact time of the magnetic force on the particles are also discussed. To the best of the authors' knowledge, the improvement by the increased impact time has not been studied in detail so far and, thus, will be addressed in this work. In this context, an artificial exponential magnetic field that approximates the field of a Halbach array and acts as an upper limit consideration is applied to different impact lengths within a predefined magnetic domain. To compare the impact of the field parameters, the total magnetic energetic effort is kept constant as a reference for studying variations of impact length. The results reveal that a longer impact length increases the attraction performance enormously. However, for the same magnetic effort, a longer impact length with a lower magnetic field strength leads to the same attraction of the particles as a shorter one with higher field strengths. Since it is easier to generate lower field strengths, the usage of arrays to realize a longer impact length is preferable.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67762121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-02DOI: 10.1109/LMAG.2022.3233222
Nan N. Liu;Yulia A. Alekhina;Alexander P. Pyatakov;Nikolai S. Perov;Boris B. Kovalev;Gleb B. Sukhorukov;Alexander M. Tishin;Tomomasa Moriwaki;Kenta Nakazawa;Yuko Ichiyanagi
Magnetic and magnetothermal properties of annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles with diameter value, ranging from 9 to 35 nm, have been investigated and compared with earlier investigated unannealed Zn 0.2 Mn 0.8 Fe 2 O 4 magnetic nanoparticles (MNPs). A single-phase spinel structure was observed in both types of MNPs. It has been demonstrated that for the large annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles (24.7, 31.4, 35.1 nm) the value of specific absorption rate (SAR) is proportional to the amplitude of the magnetic field as ∼ H 4 . However, for earlier investigated unannealed Zn 0.2 Mn 0.8 Fe 2 O 4 MNPs, superquadratic dependence SAR ∼ H 5 have been found starting from 13 nm. Significant change of dependence of the character of SAR (d) may be explained by low values of hysteresis area of small annealed MNPs and, thus, dominant role of Néel relaxation in these annealed Zn 0.2 Mn 0.8 Fe 2 O 4 nanoparticles.
{"title":"Investigation of Impact of the Annealing on Magnetothermal Properties of Zn0.2Mn0.8Fe2O4 Nanoparticles","authors":"Nan N. Liu;Yulia A. Alekhina;Alexander P. Pyatakov;Nikolai S. Perov;Boris B. Kovalev;Gleb B. Sukhorukov;Alexander M. Tishin;Tomomasa Moriwaki;Kenta Nakazawa;Yuko Ichiyanagi","doi":"10.1109/LMAG.2022.3233222","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3233222","url":null,"abstract":"Magnetic and magnetothermal properties of annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles with diameter value, ranging from 9 to 35 nm, have been investigated and compared with earlier investigated unannealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 magnetic nanoparticles (MNPs). A single-phase spinel structure was observed in both types of MNPs. It has been demonstrated that for the large annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles (24.7, 31.4, 35.1 nm) the value of specific absorption rate (SAR) is proportional to the amplitude of the magnetic field as ∼\u0000<italic>H</i>\u0000<sup>4</sup>\u0000. However, for earlier investigated unannealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 MNPs, superquadratic dependence SAR ∼\u0000<italic>H</i>\u0000<sup>5</sup>\u0000 have been found starting from 13 nm. Significant change of dependence of the character of SAR\u0000<italic>(d)</i>\u0000 may be explained by low values of hysteresis area of small annealed MNPs and, thus, dominant role of Néel relaxation in these annealed Zn\u0000<sub>0.2</sub>\u0000Mn\u0000<sub>0.8</sub>\u0000Fe\u0000<sub>2</sub>\u0000O\u0000<sub>4</sub>\u0000 nanoparticles.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67763010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1109/LMAG.2024.3379164
{"title":"TechRxiv: Share Your Preprint Research with the World!","authors":"","doi":"10.1109/LMAG.2024.3379164","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3379164","url":null,"abstract":"","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"14 ","pages":"1-1"},"PeriodicalIF":1.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10477288","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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