The phase-field models for solidification, and their governing equations and parameters are briefly introduced. The difference in the sharp interface limit and thin interface limit models are qualitatively explained. The numerical examples of the phase-field simulations on coarsening process, solidification of multi-component alloy and multi-phase alloy, microstructure evolution during rapid solidification and dendrite growth of a faceted crystal are demonstrated with their theoretical backgrounds.

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In situ atomic force microscopy (AFM) was utilized to study growth processes of several macromolecular crystals. Correlation between crystal structure, surface morphology, and growth mechanisms of faces of macromolecular crystals that have screw axes perpendicular to them was demonstrated. Thus the {001} faces of orthorhombic catalase, ribosomal 50 s subunit, trigonal trypsin, and tetragonal Bence-Jones protein (BJP) crystals grow by successive deposition of n alternating, symmetry-related layers with a thickness of d00n＝1/n l c l. For crystallization of glucose isomerase crystals from the supersaturation dependencies of tangential step rates and critical step lengths kinetic coefficient of steps and the free energy of the step edge were estimated respectively. Incorporation of the individual virions into the step edge on the surface o Cucumber Mosaic Virus (CMV) crystals was visualized and attachment frequencies and probabilities were estimated.

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It is demonstrated from the experiments using an advanced fast dynamic light scattering technique that the nucleation of CaCO3 in microgravity is 10000 times more difficult than in gravity. Ranging from low to high supersaturations, foreign bodies plays a more comprehensive role in nucleation than we expected, depending on the size and -contact angle- of the foreign bodies. It appears from our results that heterogeneous nucleation in microgravity becomes much more difficult due to the elimination of convection, and genuine homogeneous nucleation becomes possible.

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Several research works had been carried out by one (K.W.) of the authors, in order to understand a formation process of bovine insulin aggregates and crystals consisting of 2Zn-insulin hexamers. Concentration changes of the supersaturated solution of 2Zn-insulin during crystallization revealed that the aggregate of insulin at the early stage is composed of four insulin hexamers by a self-assembly theory. Light scattering from the solution during insulin aggregation, which was monitored by a dynamic light scattering (DLS) method, suggested that aggregates grow up to 600～800 nm in the solution phase by a diffusion limited aggregation (DLA) process of insulin hexamers. Images of insulin precipitates dried from the supersaturated solutions were taken by a canning electron microscopy (SEM). The images indicated that the insulin crystals are formed via spherical aggregates having about 1 mm size. Experiments of insulin crystallization under a strong magnetic field revealed that crystals grow up to about 2 mm in diameter in the bulk solution. Including our previous results, a formation process of insulin aggregates and crystals are discussed with comparison to a classical homogeneous nucleation mechanism. The effects of aggregates on quality of crystals are also discussed with reference to microgravity experiments.

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This article reviews the results of a numerical simulation study carried out for the melting experiment of GaSb/InSb/GaSb sandwich structured samples that was conducted previously by the authors under normal and micro gravity conditions. Relative contributions of the natural and Marangoni convective flows to the melting process were discussed. Numerical simulation results show that under the normal gravity condition the melting in the lower part of the sample was enhanced by the solutal natural convection. This result suggests that the solutal natural convection was dominant in the melting experiment under the normal gravity condition. Under the same conditions, the heavier component sinks to the lower part of the melt, and the concentration gradient along the free surface becomes very gentle. It was also observed that the thermal Marangoni convection enhaced the melting in the parts near the free surfaces. Results also show that the flow patterns of the thermal Marangoni and solutal natural convections show a periodic oscillatory behavior.

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It is crucial to evaluate the induction time of nucleation for obtaining high quality protein crystals in space. A new method is proposed based on the classical nucleation theory to define the time dependent character of the protein crystallization region in the phase diagram. Various concentrations of Hen Egg White lysozyme was crystallized with NaCl, and the time when the crystals appeared was studied. The experimental data fitted fairly well with the estimation supporting the validity of the proposed method.

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Experiments to determine the effect of surface tension on condensate flow of a binary mixture were carried out using an apparatus in which water-ethanol vapor mixture was condensed on a flat plate. The results of experiments carried out under a ground condition showed that the condensation patterns could be divided into three modes, i.e., filmwise, streaky and dropwise, corresponding to the vapor concentration and degree of surface subcooling. The results of microgravity experiments carried out in the MGLAB dropshaft showed that the condensed liquid in a microgravity condition formed into droplets with an increase in diameter by imbibing of the small droplets when streaky or dropwise condensation appeared under a ground condition. In this case, condensate flow in the opposite direction to that of the vapor flow by Marangoni convection was not observed under a microgravity condition. There was no significant difference in vapor temperature or pressure before and after the dropping.

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Recent space experiments on semiconductor materials are overviewed. Compositionally homogeneous crystal growth, detouched solidification, crystal growth from the vapor phase, basic researches on crystal growth, researches on Marangoni convection, development of simulation in the field of fluid flow analysis and crystal growth, data base on microgravity experiments are briefly reviewed.

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It has passed 10 years since the drop shaft facility at Japan Microgravity Center ( JAMIC) has started its operation. In this opportunity, I summarized the results of the microgravity experiments utilizing JAMIC drop shaft facility in this paper. Most of those experiments were related to the research and development (R &D) projects provided by New Energy and Industrial Technology Development Organization (NEDO). The characteristic of those projects was most of that were conducted by the international cooperation researches, and many experimental researches utilizing microgravity environment were carried out with foreign researchers. The results of the past R & D projects and the outlines of the ongoing projects were shown, then the results of the microgravity experiments conducted through the R & D projects were described by each research fields. Some examples that the experimental results has moved to practical use were introduced and the expected experimental researches in the future were shown. Furthermore, the issues of the microgravity experiments utilizing JAMIC drop shaft facility and its solutions were referred.

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Two times of TR-1A sounding rocket combustion experiments have been carried out to explore the flame propagation mechanism in the droplet-vapor-air mixtures. From these experiences, how to carry out the good combustion science in the space are discussed considering the microgravity combustion history and the organization system of space experiments. The most important point for the researchers is the good explanation of their science to the space agencies and the hardware makers. On the other hand, that for the space agencies and the hardware makers is the flexible operation for the scientific demand.

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The Combustion Experiment Module (CEM) was developed and launched for micro-gravity experiment used the sounding rocket TR-IA#5 and #7. We describe lessons learned through development of the CEM from a viewpoint of equipment development.

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Recently, the research scenario for fundamental physics under microgravity was prepared through comprehensive discussions in a large team of Japanese scientists on physics. In the scenario, the primary concept of necessity for microgravity is focused on the correlations between gravity effects and fluctuation in multiparticle system, and as a result, three sets of research domain are identified, namely, macroscopic quantum phenomena, fluid dynamics near critical point, and nonlinear phenomena and non-equilibrium thermodynamics. The scenario will serve as a guide for researchers who may have interest in space utilization program in the discipline of fundamental physics and also as an input to NASDA strategic plans.

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