PubMed Health⌕ Search

Biomedical subjects

Masayori Suwa

Publications and source records attributed to Masayori Suwa.

9 recordsLinked to original sources
PubMed2006

Magnetophoretic velocity modulation mass analysis of a single microparticle in an atmosphere.

A new principle of the magnetophoretic velocity modulation mass analysis of microparticles, which can determine simultaneously the mass and magnetic susceptibility of a single microparticle, has been proposed, and the measurement system was constructed by applying a magnetophoretic force on a falling microparticle through a magnetic field gradient in an atmosphere. A polystyrene microparticle as a test particle adsorbed on a glass plate was selectively knocked off by a pulsed Nd:YAG laser impact into a narrow gap of pole pieces of permanent magnets having a magnetic field gradient with a maximum intensity of 850 T2 m(-1). The falling particle was irradiated by a He-Ne laser, and the scattered light was detected through a slit array mask as a function of time. A bundle of spiked signals of scattered light intensity was analyzed to obtain velocities, which gave acceleration and deceleration of the falling particle. On the basis of the equation of motion under the magnetic field gradient, the mass and magnetic susceptibility of the test particle were reasonably determined.

Atmosphere↗
PubMed2006

Raman microprobe spectrometer installed in a super-conducting magnet.

A Raman microprobe spectrometer that could be installed in the bore of a cryogen free super-conducting magnet (10 T) was designed and constructed for the investigation of the external magnetic field effect on the Raman spectra of molecular aggregates in solutions and at interfaces. The performance of the present instrument was demonstrated by measuring the magnetic field effect (0 - 10 T) on the resonance Raman spectra of diprotonated meso-tetra-(sulfonatophenyl)porphine aggregates in an acidic solution. The Raman shifts of the aggregates were not significantly influenced even in 10 T. However, the relative intensity of 1123 cm(-1) peak (nu(C(a)-N)) was interestingly enhanced about 20% under the magnetic fields higher than 2.5 T.

Journal Article↗
PubMed2004

High-magnetic-field electromagnetophoresis of micro-particles in a capillary flow system.

The electromagnetophoretic migration of micro-particles in a capillary flow system was demonstrated using a homogeneous magnetic field applied at right angles to an electric current. We utilized a high-magnetic-field of 10 T for observing this phenomenon. When the direction of the electric current was alternatively changed, polystyrene latex particles in a flowing aqueous medium migrated zigzag affected by a Lorentz force exerted on the medium. Carbon particles also migrated in the same manner with polystyrene particles. Further, we tried the electromagnetophoretic migration of biological particles, such as yeasts and human red blood cells. The migration velocity component perpendicular to the flow was proportional to both the electric current and the magnetic flux density. These results proved that the dominant force of the zigzag migration was an electromagnetophoretic buoyancy generated in the flowing medium. Moreover, it was found that the force exerted on the particles in the magnetic field of 10 T was sufficient for the desorption of particles adsorbed on the capillary wall.

Carbon↗
PubMed2004

New principle of magnetophoretic velocity mass analysis.

We propose a novel principle of velocity mass analysis of a micro-particle using magnetophoretic force. The new method can determine the mass of a particle from its magnetophoretic velocity change in a high magnetic field gradient in a low viscous medium such as air. In the present study, the new principle was demonstrated by the magnetophoretic acceleration of an aqueous manganese(II) chloride micro-droplet and the deceleration of a water micro-droplet in the atmosphere. The observed velocity change was analyzed taking into account the mass of the droplet through the acceleration term of the equation of motion. The experimental results proved that the inertia force in the magnetophoretic velocity of a micro-particle could be detected in air. The present method provided an innovative mass analysis method without any ionization of the sample.

Journal Article↗
PubMed2004

Migration analysis of micro-particles in liquids using microscopically designed external fields.

The recent development of new migration methods of micro-particles in liquids using various external fields is reviewed. The combination of a laser scattering force and a photothermal effect produced photothermal-conversion laser-photophoresis. A dielectric field generated in a planer or a capillary quadrupole electrode realized dielectrophoresis. Using a micrometer-scaled magnetic field gradient, the "Magnetophoretic velocimetry" of micro-particles was invented. Furthermore, the Lorentz force generated by combining an electric field and a magnetic field was utilized for electromagnetophoresis. These new methods were overlooked and the advantages in analytical use were discussed.

Journal Article↗
PubMed2003

Magnetophoresis and electromagnetophoresis of microparticles in liquids.

The magnetic field-induced migration of particles in liquids is a highly-promising technique for the micro-separation analysis of bioparticles, such as cells and large DNA. Here, new methods that make use of magnetophoresis and electromagnetophoresis to induce the migration of microparticles in liquids are briefly reviewed. Magnetic force and Lorentz force are utilized in the new methods. Some typical examples of the use of these methods are described, and the advantages of using a superconducting magnet for them are demonstrated.

Cell Separation↗
PubMed2003

Magnetophoretic velocity of microorganic droplets adsorbed by dysprosium(III) laurate in water.

By using an improved apparatus for the observation of magnetophoresis, the magnetophoretic velocity of 2-fluorotoluene droplets including lauric acid was measured in aqueous dysprosium(III) solution. The magnetophoretic velocity of pure 2-fluorotoluene droplets was proportional to the square of the radius. On the other hand, the velocity of the organic droplets including lauric acid in the dysprosium(III) solution showed a deviation from the square radius relationship, more remarkably in smaller droplets than 2 microm in radius. These results indicated that the dysprosium(III)-laurate complex was formed at the liquid-liquid interface. This study is the first report on the detection of the interfacial complex by the magnetophoresis of the microdroplet.

Adsorption↗
PubMed2002

Magnetophoretic velocimetry of manganese(II) in a single microdroplet in a flow system under a high gradient magnetic field generated with a superconducting magnet.

An experimental system for magnetophoretic velocimetry, which could determine the volume magnetic susceptibility of a single particle dispersed in a liquid phase from a magnetophoretic velocity, has been developed. A micrometer-sized high-gradient magnetic field could be generated in a capillary by a pair of iron pole pieces in a superconducting magnet (10 T). The magnetophoretic behavior of a single particle in a capillary flow system was investigated under the inhomogeneous magnetic field. From the magnetophoretic velocity of a polystyrene latex particle dispersed in a MnCl2 aqueous solution, the product of the magnetic flux density and the gradient, B(dB/dx), was determined as a function of the position along the capillary. The maximum value of B(dB/dx) was 4.7 x 10(4) T2 m(-1), which was approximately 100 times higher than that obtained by two Nd-Fe-B permanent magnets (0.4 T). Organic droplets extracting manganese(II) with 2-thenoyltrifluoroacetone and tri-n-octylphosphine oxide from MnCl2 solution were used as test samples. The difference of the volume magnetic susceptibility between the droplet and the medium could be determined from the magnetophoretic velocity. This method allowed us to continuously measure a volume magnetic susceptibility of 10-6 level for a picoliter droplet and to determine manganese(II) in the single droplet at the attomole level.

Journal Article↗