Effect of static magnetic fields on the budding of yeast cells.

The effect of static magnetic fields on the budding of single yeast cells was investigated using a magnetic circuit that was capable of generating a strong magnetic field (2.93 T) and gradient (6100 T² m⁻¹). Saccharomyces cerevisiae yeast cells were grown in an aqueous YPD agar in a silica capillary under either a homogeneous or inhomogeneous static magnetic field. Although the size of budding yeast cells was only slightly affected by the magnetic fields after 4 h, the budding angle was clearly affected by the direction of the homogeneous and inhomogeneous magnetic fields. In the homogeneous magnetic field, the budding direction of daughter yeast cells was mainly oriented in the direction of magnetic field B. However, when subjected to the inhomogeneous magnetic field, the daughter yeast cells tended to bud along the axis of capillary flow in regions where the magnetic gradient, estimated by B(dB/dx), were high. Based on the present experimental results, the possible mechanism for the magnetic effect on the budding direction of daughter yeast cells is theoretically discussed.

Microscopic Faraday rotation measurement system using pulsed magnetic fields.

Microscopic Faraday rotation measurement system using a pulsed magnetic field has been constructed, which can be applied to micron sized diamagnetic and paramagnetic materials. A pulsed magnetic coil could generate a maximum magnetic flux density of about 12 T. The performance of the microscopic Faraday rotation apparatus was demonstrated by the measurement of the Verdet constant V of a polystyrene particle, after the calibration of the pulsed magnetic flux density using a glass plate as a standard material. Also, the magneto-optical rotation dispersion of some diamagnetic substances have been measured and analyzed with V=alambda(-2)+b. The values of a and b were compared to their magnetic susceptibilities.

Magnetic susceptibility measurement of a microdroplet interface using a magnetic circuit.

A conventional method to measure the magnetic susceptibility of a microdroplet in a glass capillary has been constructed by using a magnetic circuit (2.82 T) with a high magnetic field gradient (B(dB/dz) = 3900 T(2)/m). The magnetophoretic velocity of a toluene droplet with ferrocene dispersed in 1 M HCl aqueous solution including K(3)[Fe((III))(CN)(6)], Fe((III))Cl(3) and cetyltrimethylammonium bromide (CTAB) was measured and the volume magnetic susceptibility of droplets was determined. From the dependence of the magnetic susceptibility on the radius of the droplets, the interfacial magnetic susceptibility of the droplets adsorbed by Prussian blue aggregates was determined. The interfacial concentration of Prussian blue of individual droplet calculated from the observed magnetic susceptibility indicated that the interfacial concentration of Prussian blue are different even in similar sized droplets, suggesting inhomogeneous formation of interfacial aggregates.

Magnetic susceptibility measurements of solutions by surface nanodisplacement detection.

A new principle to measure the magnetic susceptibility of a solution was proposed; it utilized the displacement of solution surface caused by the magnetic force applied to the solution. The interfacial displacement was measured with the sensitivity of 5 nm from a change of the interference fringes, so called Newton Ring, generated from the solution surface and an upper surface of a small plano-convex lens on the bottom wall of a cell. The surface displacement measurement was carried out in a homemade cell attached by one or two small Nd-Fe-B magnets. The performance of this method was investigated by the measurements of magnetic susceptibility of manganese(II) chloride solution and some lanthanide(III) solutions. An excellent linear relationship between the magnetic susceptibility and the interfacial displacement was observed for each solution system. Then, it was demonstrated that this relationship could be used for the determination of the magnetic susceptibility of solutions or the concentration of a solute by using the manganese(II) solution as a standard solution.