A method for measuring the distribution of electroosmotic flow velocity and electric field intensity in a microchannel by micro-particle image velocimetry (μPIV) is described. Two types of particles with differing electric surface properties were used as tracer particles in order to subtract the velocity component due to the effects of the electrophoretic force from the velocity of the particles. A calibration experiment was first carried out using a one-dimensional microchannel to obtain the correlation functions between the apparent electric field intensity and the velocity of the two particles. μPIV measurements were then carried out in the target microchannel to measure the electroosmotic flow and electric fields by using the same two tracer particles and the correlation function. To validate the present method, experiments were conducted for two types of microchannels. One was a straight channel that consisted of a material different from that used in the calibration, and the other was a corrugated channel. The results were compared with those of an experiment using fluorescent dye, as well as with numerical simulations. Good agreement was observed in both comparisons, affirming the validity of the proposed method.

We have studied EuPtP, which undergoes two successive valence transitions at T A ∼ 240 K and T B ∼ 200 K by 31 P-nuclear magnetic resonance (NMR) measurements. From the analysis of NMR spectra, we obtained plausible ordered structures and Eu valence states in three phases divided by T A and T B . These ordered structures well explain observed inequivalent P sites and the intensity ratio of the NMR spectra arising from these P sites. The results are also in good accordance with mean Eu valence measured by the x-ray absorption spectroscopy. We also discuss Eu 4f states and the origin of the transitions from the measurements of nuclear spin lattice relaxation rate and hyperfine coupling constant.

Numerical simulations were carried out for the red blood cell (RBC) suspended in a stationary fluid. Elastic spring model were used to calculate the RBC membrane, and finite volume method was used to solve the flow field. The magnetic effect on the RBC was model by considering the anisotropic diamagnetic susceptibility of the phospholipids and transmembrane protein. The torque produced by these components at each element edge of the mesh generated on the cell surface was first calculated, and then the force applied to each node was evaluated. Experimental measurement of the RBC behavior in microchannels was also carried out under uniform magnetic field with the intensity of 8T using microscope and high-speed video camera to validate the present computation. The numerical simulation showed that the RBC rotates and orients so that the concave surface aligned parallel to the magnetic field. This behavior and the time that was required for the RBC to fully orient agreed well with the present experimental results. These results affirm not only the validity of the present method, but also the possibility of using microchannels to evaluate the magnetic characteristics of the RBCs.

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Anumerical model that considers the infiuence of the uniform magnetic field on the membrane of the red blood cell ( RBC ) is described in this study ． The spring − network model which discritizes the RBC membranes into springs and mass elements was employed ， The magnetic effect of the phos − pholipid and the transmembrane proteill which composes the RBC membrane is then modeled by applying rotary torque on the edges of these elements ． Further ， the RBC computation was coupled with Huid computation using the Immersed Boundary methQd ， The behavior of the RBC was com − pared with experimental results which showed a reasonab 且 e correspondence con 丘rming the validity of the present modeL Furthermore， the magnetic force distributions on the membrane showed that the curvature at the edge of the RBC influences the RBC rotation domina皿 tly，The results also showed that the overall anisotropic diarnagnetic susceptibnity of the RBC call be predicted from the present modeL Key Wo 5： Red Blood Cell ， Uniform Magnetic Field ， Numerical Simulation