| Project/Area Number |
10480138
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
環境保全
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| Research Institution | Hokkaido University |
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Principal Investigator |
FURUKAWA Yoshinori Hokkaido Univ., Inst.Low Temp.Sci., Assoc.Prof., 低温科学研究所, 助教授 (20113623)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Tatsuo Hokkaido Univ., Inst.Low Temp.Sci., Assoc.Prof., 低温科学研究所, 助教授 (20001844)
YOKOYAMA Etsuro Yamaguchi Univ., Dept.Engineering, Assoc.Prof., 工学部, 助教授 (40212302)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1999: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1998: ¥7,100,000 (Direct Cost: ¥7,100,000)
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| Keywords | polycrystalline ice particle / ozone hole / acid materials / actual distribution coeficient / grain boundary / uni-directional growth / Mach-Zehnder interferometer / 氷結晶 / 界面不安定 / 平衡分配係数 / 偏析係数 / 一方向成長 / 画像解析 / 光干渉法 / 一方向凝固 / 干渉計 / パターン形成 / 画像処理 |
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| Research Abstract |
Uni-directional growth experiments of ice crystals in the water including a solute of acid or salt were carried out using a newly developed growth apparatus in combination with a Mach-Zehnder interferometer. Both the pattern evolutions of ice/water interfaces and the distributions of solute concentrations in front of interfaces were observed simultaneously.
The interfacial patterns, which were completely flat at the initial stage of the growth, were changed to those composed by the array of regular finger cells. Then the boundaries between the neighboring cells can be regarded as the grain boundaries. Consequently, it means that the regular row of grain boundaries was formed along the interfaces. The distributions of solute concentrations were determined by analyzing the shifts of interference fringes at the vicinity of interfaces, and the actual concentrations of solutes on the interfaces were also determined quantitatively. The uptake abilities of solutes into the ice crystals through the interfaces were first discussed using the results of both observations.
As a result, we clarified that, when the interfacial patterns were still flat, the amount of solute rejected at the interface during the ice growth was completely consistent with the solute amount predicted by the calculation based on the equilibrium distribution coefficient of the solute against the ice crystal. However, as soon as the interfaces were changed to the perturbed ones, the mass balance of the solute completely disappeared. This means that the solutes were incorporated along the grain boundaries.
In conclusion, we determined that the actual distribution coefficients are about 0.35. This value is extremelylarger than the equilibrium distribution coefficients (0.01 or less for almost all solutes). This result strongly suggests that the grain boundaries can incorporate a large quantity of acid solutes and the polycrystalline ice particles can work as a storehouse of acid materials.
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