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Space Utilization Research Program
Introduction to Major Research Themes
SURP's ground-based research as initiative and common basic research

1) Crystal Growth of Compound Semiconductor
Research Team Leader:
Kyoichi Kinoshita
(NTT Basic Research Laboratories, Senior Research Scientist, Supervisor)
Pb1-xSnxTe Crystals Grown in the FMPT Mission aboard the Space Shuttle "Endeavour"

The InxGa1-xAs ternary mixed crystal is very promising in the field of optical communications. In this study, we attempt to prove the advantage of microgravity by manufacturing uniform, single crystals of In0.3Ga0.7As which have never been grown on the ground suck crystals expected to be substrates of 1.3 micro m wavelength laser diodes. This space experiment seeks to grow crystals free from perturbations which exist even in microgravity. Crystals will be grown from a feed in which the concentration gradient offsets the effect of convection due to residual accelerations in microgravity.


2) Modeling and Precise Experiments of Diffusion Phenomena in Melts under Microgravity
Research Team Leader:
Toshio Itami
(Hokkaido University,
Assistant Professor)

In molten materials, the existence of chemical order is presumed. The diffusion behavior seems to be influenced deeply by this chemical order. Recently, much attention has been focused on the melts of metals, alloys and semiconductors because these melts are regarded as complex liquids with chemical or particular order rather than simple liquids with a random assembly of atoms. In this research project the diffusion mechanism will be studied, using accurate diffusion with particular interest on its relation to liquid structures.
Gas
Liquid
Solid


3) Marangoni Convection Modeling Research
Research Team Leader:
Shinichi Yoda
(NASDA, Senior Engineer)
Lead Scientist:
Yasuhiro Kamotani
(Case Western Reserve University, Professor)

Marangoni convection is the main factor causing flow in under microgravity. Thus, Marangoni convection experiments have been conducted relatively often in the fluid field, with both steady and oscillating flows clarified. So far, steady state Marangoni has been clarified, but the transition from the steady state to the oscillating state and the mechanism of oscillating flow are not yet fully understood. In this study, we will try to construct a model focusing on transformation of a free surface; verify this model by experimental, numerical, and theoretical methods; and clarify the Marangoni Convection phenomenon.

*Marangoni convection is the flow due to the surface tension (liquid-to-liquid, or liquid-to-gas) difference which is generated by a temperature or concentration gradient. It is difficult to observe this phenomenon on the ground due to thermal convection, but it becomes the main factor affecting flow in microgravity.


4) Effects of Microgravity on the Signal Transduction and Gene Expression in Osteoblasts
Research Team Leader:
Atsushige Sato
(Tokyo Medical & Dental University, Professor Emeritus)
(SURP Advisor)
Mouse osteoblast - derived MC3T3-E1 cell culture.

Restriction of bone formation in microgravity has been observed, but its mechanism at the cellular level or molecular level is not thoroughly understood. In this study, we will investigate secondary signals produced in the cell through simulated microgravity and high gravity on the osteoblast, whose role is the formation of bone, and further survey the gene expression by the molecular biology method. The results will contribute not only to bone biology, but also to the remedy and prevention of osteoporosis, a disease from which astronauts and older people suffer.


Last Updated : December 17, 1999

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