Magnetic resonance absorption in isolated metal/insulator/metal nanodot arrays with transmission geometry

Vo, T.S.,Surabhi, S.,Luong, C.H.,Yoon, S.G.,Lee, K.D.,Park, B.G.,Jeong, J.R. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.7

In this study, we have systematically investigated a magnetic resonance absorption and tunability of absorption wavelength in isolated metal-insulator-metal (MIM) nanodot arrays with transmission geometry. The elemental electromagnetic resonances and their hybridizations are studied using 3-dimensional finite-difference time-domain (FDTD) calculation and resonance properties including the resonance peak tunability, magnetic permeability and quality (Q) factor are characterized with respect to the coupling strength. We have found the existence of electric and magnetic resonance mode in the MIM (Au/MgF<SUB>2</SUB>/Au) structure and the magnetic resonance has larger wavelength tunability than the electric resonance. The absorption cross section calculation revealed that absorption is the dominant extinction process at the magnetic resonance only. Magnetic permeability (μ) calculations for the various MIM parameters showed the maximum value of the imaginary part of μ is 16.1 with Q factor of 9.2 when the size of nanodot is 200 nm and the inter-dot distance is 300 nm. The presented calculations can be used to tune the response of the magnetic resonance absorption with a variable resonance wavelength and Q factor by using the simple MIM structures with transmission geometry.

Magnetic resonance absorption in isolated metal/insulator/metal nanodot arrays with transmission geometry

Thanh Son Vo,Srivathsava Surabhi,Chi Hieu Luong,윤순길,이경동,박병국,정종율 한국물리학회 2015 Current Applied Physics Vol.15 No.7

In this study, we have systematically investigated a magnetic resonance absorption and tunability of absorption wavelength in isolated metal-insulator-metal (MIM) nanodot arrays with transmission geometry. The elemental electromagnetic resonances and their hybridizations are studied using 3- dimensional finite-difference time-domain (FDTD) calculation and resonance properties including the resonance peak tunability, magnetic permeability and quality (Q) factor are characterized with respect to the coupling strength. We have found the existence of electric and magnetic resonance mode in the MIM (Au/MgF2/Au) structure and the magnetic resonance has larger wavelength tunability than the electric resonance. The absorption cross section calculation revealed that absorption is the dominant extinction process at the magnetic resonance only. Magnetic permeability (m) calculations for the various MIM parameters showed the maximum value of the imaginary part of μ is 16.1 with Q factor of 9.2 when the size of nanodot is 200 nm and the inter-dot distance is 300 nm. The presented calculations can be used to tune the response of the magnetic resonance absorption with a variable resonance wavelength and Q factor by using the simple MIM structures with transmission geometry.

Design and Implementation of Portable NMR Probe Magnet

Gao Junxia,Zhang Yiming,Tian Jiashen 한국자기학회 2017 Journal of Magnetics Vol.22 No.1

The NMR’s probe consists of the static magnetic field generator (magnetic source) and the RF coil. It is very strict for the homogeneity of the static magnetic field intensity of the magnetic source, so the cost of the magnetic source is more expensive in the entire nuclear magnetic resonance instrument. The magnetic source generally consists of electromagnet, permanent magnet and superconducting magnet. The permanent magnet basically needs not to spend on operation and maintenance and its cost of manufacture is much cheaper than the superconducting magnet. Therefore, the permanent magnet may be the only choice for the static magnetic field device if we want to use the magnetic resonance instrument as an analyzer for production by reducing price. A new probe magnet was developed on the basis of the permanent magnet ring in this paper to provide a technological way for reducing the manufacturing cost, weight and volume of the existing nuclear magnetic resonance instrument (including MRI) probe.

자기공명분석기에 의한 반사성 교감신경성 위축증의 치험

김진수,곽수달,김정순,옥시영,차영덕,박욱,Kim, Jin-Soo,Kwak, Su-Dal,Kim, Jun-Soon,Ok, Sy-Young,Cha, Young-Deog,Park, Wook 대한통증학회 1993 The Korean Journal of Pain Vol.6 No.2

Reflex sympathetic dystrophy is a syndrome characterized by persistent, burning pain, hyperpathia, allodynia & hyperaesthesia in an extremity, with concurrent evidence of autonomic nervous system dysfunction. It generally develops after nerve injury, trauma, surgery, et al. The most successful therapies are directed towards blocking the sympathetic intervention to the affected extremity by regional sympathetic ganglion block or Bier block with sympathetic blocker; other traditional treatments include transcutaneous electrical stimulation, immobilization with cast & splint, physical therapy, psychotherapy, administration of sympathetic blocker, calcitonin, corticosteroid and analgesic agents. The purpose of this report is to evaluate and describe the effects of magnetic resonance following unsatisfactory results with traditional treatments of RSD. A 17 year old female patient, 1 year earlier, had received excision and drainage of pus at the right femoral triangle due to an injury caused by a stone. Afterwards, she experienced burning pain, knee joint stiffness, and muscle dystrophy of the right thigh, especially when standing and walking. Despite a year of number of traditional treatments such as: lumbar sympathetic block, continuous epidural analgesia, transcutaneous electrical stimulation, & administration of predisolone, her pain did not improve. Surprisingly, the patients was able to walk free from pain and difficulty after just one application of magnetic resonance. The patient has been successfully treated with further treatment of two to three times a week for approximately ten weeks. More recently, magnetic resonance has been demonstrated to produce effective results for the relief of pain in a variety of diseases. From our experiences we recognize magnetic resonance as a therapeutic modality which can provide excellent results for the treatment of RSD. It has been suggested that polysynaptic reflex which are disturbed in RSD may be modulated normally on the spinal cord level through the application of magnetic resonance.

Magnetic Properties of Cobalt-Ion-Implanted SiO₂ Thin Films

F. Yildiz,H. J. Lee,Y. H. Jeong,S. Kazan,B. Aktas,J. H. Song 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

The physical properties of magnetic-ion-implanted nanoparticle systems depend on the preparation and processing conditions, and this fact may be utilized to design a material system with desired properties. For this purpose, the magnetic properties of various Co implanted SiO₂ thin films were systematically studied. SiO₂ thin films were grown on Pt/Ti/SiO2/Si (100) substrates by using thermal evaporation, and Co ions of different energies (40 and 100 keV) and doses (1, 3, 7, 10, 13 × 1016 ion/㎠) were implanted into the films. Magnetization, ferromagnetic resonance (FMR), and scanning electron microscope (SEM) measurements for the films were carried out either as-prepared or after annealing at 600 ℃. While 40 keV Co ions were spread under the surface of the films and the internal field did not change significantly with dose, 100 keV ions went deeper into the films, and their internal field changed with dose. Post-annealing further induced Conanoparticles with different shapes and sizes in the films. In general, magnetization measurements showed that the freezing temperature of the films shifted to higher temperatures with increasing dose. FMR absorption spectra were recorded as a function of magnetic field at room temperature and the effective magnetization was calculated from the FMR data. We found that the effective magnetization increased with dose while the magnetic anisotropy decreased with dose. The physical properties of magnetic-ion-implanted nanoparticle systems depend on the preparation and processing conditions, and this fact may be utilized to design a material system with desired properties. For this purpose, the magnetic properties of various Co implanted SiO₂ thin films were systematically studied. SiO₂ thin films were grown on Pt/Ti/SiO2/Si (100) substrates by using thermal evaporation, and Co ions of different energies (40 and 100 keV) and doses (1, 3, 7, 10, 13 × 1016 ion/㎠) were implanted into the films. Magnetization, ferromagnetic resonance (FMR), and scanning electron microscope (SEM) measurements for the films were carried out either as-prepared or after annealing at 600 ℃. While 40 keV Co ions were spread under the surface of the films and the internal field did not change significantly with dose, 100 keV ions went deeper into the films, and their internal field changed with dose. Post-annealing further induced Conanoparticles with different shapes and sizes in the films. In general, magnetization measurements showed that the freezing temperature of the films shifted to higher temperatures with increasing dose. FMR absorption spectra were recorded as a function of magnetic field at room temperature and the effective magnetization was calculated from the FMR data. We found that the effective magnetization increased with dose while the magnetic anisotropy decreased with dose.

Distance-Dependent Magnetic Resonance Tuning as a New Design Principle for Responsive MRI Contrast Agents

김수민,유동원,김종찬 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Magnetic resonance imaging (MRI) is a high-resolution and clinically important imaging modality, which offers anatomical information, enabling diagnosis and prognosis of disease. A considerable effort has been investigated for the development of responsive MRI contrast agents capable of specifically indicating their local microenvironment such as pH, enzymatic activities, or redox status. In the presence of biological target, a switch in MRI contrast is triggered by the change of the relaxation efficiency which is derived from the variation of rotational dynamics or exchange rate of coordinated water, etc. Here, we introduce a new design principle of magnetism-based distancedependent modulation of the relaxation efficiency. This magnetic resonance tuning (MRET) phenomenon occurs between a paramagnetic element and a superparamagnetic element, where the T1 MRI signal is tuned ON or OFF depending on the separation distance between the two elements.

Multifunctional Magnetic Gold Nanocomposites: Human Epithelial Cancer Detection via Magnetic Resonance Imaging and Localized Synchronous Therapy

Lee, J.,Yang, J.,Ko, H.,Oh, S.,Kang, J.,Son, J.,Lee, K.,Lee, S.-W.,Yoon, H.-G.,Suh, J.-S.,Huh, Y.-M.,Haam, S. WILEY-VCH Verlag 2008 Advanced Functional Materials Vol.18 No.2

<P>Novel multifunctional magnetic gold nanocomposites (MGNCs) were synthesized for synchronous cancer therapy and diagnosis via magnetic resonance imaging (MRI). The MGNCs consist of magnetic kernels (aggregates of ultra-sensitive MnFe<SUB>2</SUB>O<SUB>4</SUB> magnetic nanocrystals wrapped in polymer) as effective MR contrast agents and silica–gold nanocomposites as hyperthermal therapeutic agents. A therapeutic antibody, Erbitux (ERB), was conjugated for specific tumor cell targeting both to localize the near-IR laser beam and to image their events through MRI. ERB-conjugated MGNCs selectively recognize the target cancer cell lines. Fluorescence images and MRI analysis show that the MGNCs are effectively taken up by the cells. ERB-conjugated MGNCs have an excellent synchronous therapeutic efficacy as a result of the therapeutic antibody and near-IR laser-induced surface plasmon resonance. Consequently, MGNCs clearly demonstrate selective imaging and treatment of human epithelial cancer simultaneously.</P> <B>Graphic Abstract</B> <P>Multifunctional magnetic gold nanocomposites (MGNCs) were synthesized from aggregates of magnetic nanoparticles wrapped in a polymer as the magnetic resonance contrast agent and a silica–gold nanocomposite shell (see figure) as an effective hyperthermal therapeutic agent. Therapeutic antibody-conjugated MGNCs have an excellent synchronous therapeutic efficacy stemming from the antibodies and NIR-laser-induced hyperthermia, which implies the potential of the MGNCs for simultaneous diagnosis and treatment of cancer. <img src='wiley_img/1616301X-2008-18-2-ADFM200700482-content.gif' alt='wiley_img/1616301X-2008-18-2-ADFM200700482-content'> </P>

Prior to Breast MRI Guidelines in Korea, Where Were We?

Hwang, Cheong Hoon,Rho, Miribi,Lee, Minah,Kim, Ga Ram,Park, Vivian Youngjean,Yoon, Jung Hyun,Kim, Min Jung Korean Society of Magnetic Resonance in Medicine 2021 Investigative Magnetic Resonance Imaging Vol.25 No.1

Purpose: To evaluate and analyze the adequacy of breast magnetic resonance imaging (MRI)s taken before publication of the 2018 recommendation in South Korea. Materials and Methods: We enrolled 87 cases of breast MRIs, from January 2010 to November 2013, taken at external hospitals in the study. Breast MRI protocol elements are divided into three categories based on the recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance: (1) Essential elements for breast MRI protocol; (2) Element to consider when evaluating imaging quality; and (3) Optional element for breast MRI protocol. Also, we divided enrolled cases into three groups based on their conducting locations -- (1) Primary hospitals, (2) Secondary hospitals, and (3) Tertiary hospitals-and analyzed them for the adequacy of imaging protocols based on the 2018 recommendation. We used a Chi-square test and Fisher's exact test to identify differences between categorical variables. Results: Over 98% of the criteria for 'essential elements for breast MRI protocol' were satisfied when compared with the 2018 Recommendation. Over 96% of the criteria for 'elements to consider when evaluating imaging quality' were also satisfied, except for the slice thickness (83.9%). Optional elements for breast MRI protocol were satisfied with various percentages. There were no statistically significant differences between groups of tertiary, secondary, and primary hospitals; however, 3 tesla of MRI (P = 0.04), subtraction image protocol (P = 0.032), and DWI protocol (P = 0.03) were used more frequently in the tertiary hospitals than in the others. Conclusion: We found that the categories of 'essential elements' and 'elements to consider when evaluating imaging quality' were satisfied at 98% and 96%, respectively, when compared with the 2018 Recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance.

Magnetic Permeability Spectra of Metamaterials Composed of Split Cut Wires Retrieved Using Circuit Theory

( Joon-hee Lim ),( Sung-soo Kim ) 충북대학교 산업과학기술연구소 2019 산업과학기술연구 논문집 Vol.33 No.1

Frequency dispersion of magnetic permeability has been theoretically predicted in a metamaterial composed of split cut wires (SCW) and cut wires (CW) separated by dielectric substrate on the basis of circuit theory. Magnetic resonance resulting from antiparallel currents between the SCW and CW is observed at the frequency of minimum reflection loss (corresponding to absorption peak) and effective resonator size can be determined. Calculating the circuit parameters (inductance L, capacitance C) and resonance frequency from SCW dimension, the frequency dispersion of permeability of Lorentz like magnetic response can be predicted as a function of resistance R. The simulated resonance frequency and permeability spectra can be explained on the basis of the circuit theory of an RLC resonator.

Magnetic Resonance-Based Wireless Power Transmission through Concrete Structures

Ji-Min Kim,Minseok Han,Hoon Sohn 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2

As civil infrastructures continue to deteriorate, the demand for structural health monitoring (SHM) has increased. Despite its outstanding capability for damage identification, many conventional SHM techniques are restricted to huge structures because of their wired system for data and power transmission. Although wireless data transmission using radio-frequency techniques has emerged vis-a-vis wireless sensors in SHM, the power supply issue is still unsolved. Normal batteries cannot support civil infrastructure for no longer than a few decades. In this study, we develop a magnetic resonance-based wireless power transmission system, and its performance is validated in three different mediums: air, unreinforced concrete, and reinforced concrete. The effect of concrete and steel rebars is analyzed.