A5081384150- Characterization and Applications of Magnetic Nanoparticles
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Microfluidic and Bio-sensing Technologies
- Geomagnetism and Paleomagnetism Studies
- Quantum and electron transport phenomena
- Magnetic Field Sensors Techniques
- Atomic and Subatomic Physics Research
- Non-Destructive Testing Techniques
- Advanced Electrical Measurement Techniques
- Superconducting Materials and Applications
- Magnetic Properties and Applications
- Force Microscopy Techniques and Applications
- Magnetic and transport properties of perovskites and related materials
- Minerals Flotation and Separation Techniques
- Particle accelerators and beam dynamics
- Superconductivity in MgB2 and Alloys
- Welding Techniques and Residual Stresses
- Theoretical and Computational Physics
- Advanced Biosensing Techniques and Applications
- Biosensors and Analytical Detection
- HVDC Systems and Fault Protection
- Surface and Thin Film Phenomena
- Ultrasonics and Acoustic Wave Propagation
- Magneto-Optical Properties and Applications
Kyushu University
2015-2024
Technische Universität Braunschweig
2021
Supercon (United States)
2008-2019
Fukuoka Prefecture Education Center
2016
Physikalisch-Technische Bundesanstalt
1992-1993
Kyoei University
1982
An oscillator which utilizes the effect of vortex motion in long Josephson tunnel junctions, i.e., flux flow, has been presented millimeter and submillimeter wave region. electromagnetic generated by is detected with a small junction as detector refined coupling configuration. Quantitative evaluation power showed that attained value 10−6 W frequency range between 100 400 GHz, far superior to previous results. Frequency magnetic field dependences present system were also measured, output was...
The nonlinear Brownian rotational relaxation of magnetic fluids for the case large excitation field was studied in relation to its biomedical applications. Fokker–Planck equation, which describes behavior fluids, solved by numerical simulation when a step or sinusoidal applied. Deviations from Debye theory were quantitatively clarified. First, it shown that response time became shorter than larger field, can be expressed terms field-dependent time. Next, amplitude ac susceptibility lower...
Effects of thermal noise on the characteristics dc superconducting quantum interference device (SQUID) have been studied. Numerical simulation SQUID operating at T=77 K has performed by taking into account noise. It is shown that voltage versus flux relation degraded considerably with The degradation becomes significant when inductance increases. Due to this degradation, there exists limitation for range available K, unlike case T=4.2 K. maximum should be around 200 pH in order avoid...
A theoretical study is made of a travelling-wave-type oscillator, which utilizes flux flow in long Josephson junction for use as local oscillator the integrated superconducting receiver system. An internal electromagnetic field flux-flow state investigated both numerically and analytically. It shown that voltage amplitude oscillation increases gradually direction reaches maximum value at end. equivalent circuit also obtained, gives dependences emitted radiation on frequency, magnetic field,...
Numerical as well experimental studies have been made of the oscillation stability for travelling-wave-type oscillator, which utilizes a vortex motion in long Josephson junction, i.e., flux flow. For steep current step dc I-V characteristic improves stability. Two kinds effects degrade steepness investigated junction overlap geometry. One is self-field effect makes inclined, and other resonant vortices induces staircaselike structure on step. We discussed method reduction these proposed...
Globally, the demand for improved health care delivery while managing escalating costs is a major challenge. Measuring biomagnetic fields that emanate from human brain already impacts treatment of epilepsy, tumours and other disorders. This roadmap explores how superconducting technologies are poised to impact care. Biomagnetism study magnetic biological origin. Biomagnetic typically very weak, often in femtotesla range, making their measurement challenging. The earliest vivo measurements...
A system is developed to magnetically measure biological antigen-antibody reactions with a superconducting quantum interference device (SQUID) magnetometer. In this system, antibodies are labeled magnetic nanoparticles of γ-Fe 2 O 3 , and the measured by detecting field from nanoparticles. setup described, sensitivity studied in terms detectable weight Magnetic particles as small 600 pg can be detected at present. An experiment also conducted reaction present system. It shown that better...
Magnetic biosensing techniques that are based on the use of bio-functionalized magnetic nanoparticles (magnetic markers) and superconducting quantum interference devices (SQUIDs) expected to have various advantages when compared with conventional methods. In this paper, we review recent progress made in techniques. First, describe most important parameters markers intended for biosensing, i.e., signal relaxation time determined by Brownian and/or Neel mechanisms. We note these significantly...
Power emission from a flux-flow-type Josephson oscillator with thin-film coupling method is studied experimentally. The thickness of one electrode the made thin enough to allow electromagnetic fields generated by be emitted through electrode. Radiation power detected superconductor-insulator-superconductor detectors, which are fabricated on top oscillator. Experimental results show that sufficient can obtained using when comparable London penetration depth. in reasonable agreement...
The effect of a damping resistance on the relation between voltage V and magnetic flux Φ dc SQUID is studied theoretically for case with large parameter βL=2LI0/Φ0 , where L loop inductance, I0 critical current, Φ0 quantum. An approximate analytical expression V-Φ obtained by replacing Josephson junctions ac current generators. It shown that becomes almost independent value βL in damping. As result, conversion efficiency dV/dΦ not degraded even as conventional without resistance. This result...
The dynamics of a magnetic fluid in rotating field the presence thermal noise were studied by performing numerical simulations based on Fokker-Planck equation. We first clarified dynamic properties simulation such as frequency dependence magnetization, field-dependent relaxation time, and M-H curve field. Using results, we modified an existing analytical model obtained empirical expression to quantitatively describe particle dynamics. results compared with experimental magnetization was...
Magnetic nanoparticles (MNPs) have been widely studied for use in biomedical applications such as magnetic particle imaging and hyperthermia. We the effect of easy axis alignment on dynamic magnetization both immobilized suspended MNPs. For samples, axes were aligned by applying a dc field during immobilization. applied ac was set so that caused field. Magnetization (M–H) curves MNPs with different degrees measured an found considerably affects their M–H curve harmonic spectra, which...
Hysteresis loss (P) of magnetic nanoparticles (MNPs) under alternating current excitation has been used to induce hyperthermia in cancer cells. We theoretically optimized the field amplitude Hac and frequency f required maximize P, while product C = Hacf did not exceed a threshold value avoid side effects biomedical applications. obtained analytical expressions for optimum values as functions MNP parameters. Almost same P could be MNPs with core diameters dc ranging over 20–40 nm if were...
Comprehensive comparison between theory and experiment has been made on the characteristics of a high-Tc dc superconducting quantum interference device (SQUID). Using theoretical expressions for SQUID characteristics, we can quantitatively predict transfer function Vφ magnetic-flux noise SΦ from parameters without any adjustable parameter. It is shown that predictions agree well with experimental results wide range parameters. This agreement shows usefulness present in design SQUID....
We have fabricated and characterized a low-noise direct-coupled magnetometer based on 100 pH YBa2Cu3O7−x dc superconducting quantum interference device (SQUID) 10 mm×10 mm SrTiO3 bicrystal substrate with 30° misorientation angle. The thin films were deposited by hollow cathode discharge sputtering patterned using conventional photolithography Ar ion beam etching. SQUID was operated flux-locked-loop electronics bias reversal. sensor had usable voltage swing of 39 μV white magnetic field noise...
A high T/sub c/ SQUID system is developed for the application to biological immunoassay. In this application, magnetic nanoparticles are used as markers perform immunoassay, i.e., detect binding reaction between an antigen and its antibody. Design set up of described. Minimum detectable amplitude flux 0.6 m/spl Phi//sub 0/ measurement bandwidth from 0.2 Hz 5 when we use a magnetometer. The noise does not increase field 0.8 mT applied in parallel SQUID. An experiment measure antigen-antibody...
We developed a prototype magnetic immunoassay system using high temperature superconductor (HTS) superconducting quantum interference device (SQUID) to investigate the performance and usability of immunoassay. The is designed measure multiple samples liquid samples, it can work in an unshielded environment at medical facility. To reduce disturbance from environmental noise, SQUID are covered with three-layers permalloy shield. shield set aluminum box which acts as RF A gradiometer 5 /spl...
ac susceptibility measurement of magnetic markers in solution was performed for the liquid phase detection biological targets. First, properties were clarified, such as size distribution, frequency dependence susceptibility, and field magnetization. Next, we demonstrated a method which used large polymer beads to immobilize prolong Brownian relaxation time bound markers. In this method, could detect by decrease that they displayed. Using detected biotin-conjugated with avidin-coated Fe3O4...
Magnetic sensing techniques have been recently developed to detect biomarkers using magnetic nanoparticles (MNPs) in liquid-phase assays. In the case of alternating current (ac) susceptibility when detecting a low number MNPs, diamagnetic signal water becomes major problem at signal-to-noise ratio. Therefore, we high-temperature superconducting-quantum-interference-device-based ac measurement system that can third-harmonic signals from MNPs. On basis nonlinear characteristic MNPs with large...