M. Iwasaka

Properties of diamagnetic fluid in high gradient magnetic fields

This study focuses on the properties of diamagnetic fluid in static magnetic fields up to 8 T with the gradient of 50 T/m. We used a horizontal type of superconducting magnet with a bore 100 mm in diameter and 700 mm long. We observed the phenomenon that the surface of the water was pushed back by magnetic fields of higher gradients. Two ‘‘frozen’’ cascades were formed at z=±50–80 mm; the surface of the water near the center of the magnet was parted, and the bottom of the water chamber appeared. The water level at both ends of the chamber was lifted up. In order to investigate the hydrodynamics of diamagnetic fluid in magnetic fields, we made a fluidic circuit with plastic tubing which passed through the superconducting magnet’s bore. When magnetic fields in the center of the bore were changed from 0 to 8 T, the flow velocity of distilled water decreased, and the flow was stopped at 8 T. A stress analysis of diamagnetic fluid in magnetic fields was carried out to explain the mechanism of these phenomena. ...

Effects of magnetic fields on fibrinolysis

In this study, we investigated the possible effects of magnetic fields on the fibrinolytic process. Fibrin dissolution was observed and the fibrinolytic activities were evaluated. First, fibrinolytic processes in magnetic fields were investigated by the fibrin plate method. We gathered solutions from the dissolved fibrin, and measured mean levels of fibrin degradation products (FDPs) in solutions. Mean levels of FDPs exposed to 8 T magnetic fields were higher than those not exposed to fields. Second, we carried out an experiment to understand how fibrin oriented in a magnetic field dissolves. FDPs in solutions of dissolved fibrins in fibrin plates were assayed. The result was that fibrin gels formed in a magnetic field at 8 T were more soluble than those not formed in a magnetic field. A model based on the diamagnetic properties of macromolecules was explained, and changes of protein concentrations in a solution in gradient magnetic fields were predicted.

Early embryonic development of frogs under intense magnetic fields up to 8 T

A possible influence of intense magnetic fields on the embryonic development of frogs was studied in reference to a potential hazard in magnetic resonance imaging technology. Some of the most serious hazardous effects that could be induced by intense magnetic fields are teratogenic effects on developing embryos. In the present experiment, the possible influence of intense magnetic fields up to 8 T on the early embryonic development of Xenopus laevis was studied. Embryos were exposed to magnetic fields up to 8 T for the period from the precleavage stage to neurula in a small glass vial. Embryos were then cultured in Brown–Caston’s medium until the feeding‐tadpole stage. No apparent teratogenic effects were observed when embryos were cultured for 20 h from the stage of uncleaved fertilized egg to the neurula stage under magnetic fields of 8 T. We conclude that static magnetic fields up to 8 T do not appreciably affect the rapid cleavage and the following cell multiplication and differentiation in Xenopus la...

Dynamic behavior of gas flow in gradient magnetic fields

The mechanism of the formation of the magnetic curtain which appears in an air atmosphere under gradient magnetic fields is studied. It is assumed that the magnetic curtain is a wall of air produced by the interaction of gradient magnetic fields with paramagnetic oxygen. Gas flow experiments in magnetic fields are carried out. The gas flow is clearly blocked by magnetic fields at 120 T/sup 2//m. A model based on molecular dynamics is proposed to explain the experimental results. Trajectories of gas flows are calculated, and the threshold value of magnetic field strength needed to block nitrogen gas flow is obtained. >

Vegard's Law in KFe(S1-xSex)2

The lattice constant and chemical composition of a specimen of a mixed crystal can be determined simultaneously on the basis of well-established single-crystal X-ray diffractometry. From the data for various compositions of the system, the relation between the two quantities, which usually follows Vegards law, can be established. An example of the application of this procedure is shown for the case of mixed crystals KFe(S1-xSex)2 (0≤x≤1). In contrast to a nonlinear relation to the nominal composition, the lattice constants are found to be linear to the composition when it is properly determined.

Enzymatic oxidation‐reduction processes under magnetic fields up to 8 T (abstract)

The question of whether magnetic fields affect enzymatic activities or not is of considerable interest in biochemistry and in biomagnetics. Xanthine oxidase, contained in liver, lungs, intestine, and other organs, catalyzes the degradation of hypoxanthine to xanthine, and xanthine to uric acid, which is the terminal waste of purine nucleotides in mammals. During the oxidation of xanthine, the enzyme releases superoxide anion radicals as intermediates which reduce ferricytochrome c (Fe3+). Superoxide anion, as well as any type of free radical, is also paramagnetic. The study is focused on whether these magnetically related enzymatic activities can be affected by magnetic fields. There is a possibility that free radicals, as intermediates, can be modified by magnetic fields of specific intensities. In our previously reported study, we examined a possible effect of magnetic fields up to 1.0 T on biochemical reaction catalyzed by xanthine oxidase, and obtained negative results. In the present abstract, we exa...

Effect of magnetic fields on the enzymatic activity of plasmin

The authors investigated the effect of magnetic fields on the enzymatic activity of plasmin concerning the dissolution of thrombus. Plasmin activity in magnetic fields up to 8 T was assessed using a synthetic substrate for plasmin, D-Val-Leu-Lys-pNA. After 40 min or more incubation, absorbance of the mixture exposed to an 8 T magnetic field at 37/spl deg/C was 7-11% lower than control sample. The results show that the enzymatic activity of plasmin was affected by a magnetic field at 8 T. This suggests that magnetic fields have an effect on the active center of the enzymatic reaction of plasmin with a substrate, especially on the hydrogen bonds of the charge-relay system.<<ETX>>

Fibrinolysis in strong magnetic fields

The authors have observed that the fibrinolytic process in strong magnetic fields up to 8 T was enhanced. In this study, they focused on the mechanism of this phenomenon. First, they observed that gradient magnetic fields eroded a fibrin gel in a specific direction. Second, they carried out an experiment to measure concentrations of fibrin in magnetic fields and concluded that redistribution of fibrin polymers concentration occurred in gradient magnetic fields up to 8 T.<<ETX>>

Dissolution of fibrin formed in magnetic fields up to 8 T

A b s t r a c f This study focuses on the possible effects o f magnetic f ields on the fibrinolytic process. Dissolution of fibrin formed with magnetic fields was observed and the fibrinolytic activities were evaluated by fibrin plate methods. A distinguishable difference was observed in the dissolution of fibrin between fibrin gel formed with a magnetic field a t 8 T and that formed without a f ie ld .