| Project/Area Number |
08455447
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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 |
高分子構造・物性(含繊維)
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SASAKI Naoki Graduate School of Sciences, Hokkaido University, Asso.Pro., 大学院・理学研究科, 助教授 (40142202)
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| Co-Investigator(Kenkyū-buntansha) |
HIKICHI Kunio Graduate School of Sciences, Hokkaido University, Pro., 大学院・理学研究科, 教授 (30000805)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1998: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1997: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Elongational flow field / Flow birefringence / Four roller mill / Coil-stretch transition / Coil-globule transition / Fluorescence microscope / Birefringent glob-ule molecule / Polyelectrolyte / コイル-グロビュール転移 / 複屈折の空間分布 / 高分子の屈曲性 / コイル-ストレッチ転移 / 蛍光標識DNA分子 / T4 phage DNA / グロビユ-ル状態 / ストップドフロー / 回転拡散係数 / 継横比 / ファージDNA分子 / 蛍光顕微鏡法 / 単分子観察 |
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| Research Abstract |
It has been well established that flexible polymers manifest a conformational transition in a well-defined elongational flow field : a coil stretch transition (CST). We investigated the CST of polymers under various conditions and tried to manipulate a polymer molecule by stretching in the elongational flow field. The elongational flow field was generated by a four-roller mill system where the response of the polymer molecule to the elongational field was monitored by a flow birefringence.
(1) Coil-globule transition of a T4 phage DNA molecule was investigated by means of the elongational flow field birefringence method in conjunction with a fluorescent micrograph method. A random coil is expected to be elongated by the flow field and generate birefringence signal while a globular molecule is considered not deformed and there should be no birefringence. The expectation was empirically revealed to be the case. A birefringent globular molecule was discovered by a comparison of the birefringence data with that of fluorescent micrograph. Such a birefringent globular molecule was found to be in the shape of an ellipsoid with an optical anisotropy by the stopped flow experiment using the four-roller mill system.
(2) A polyelectrolyte changes its flexibility with the salt concentration in the solution. The flexibility change of the polyelectrolyte was quantified by the CST observation in the elongational flow. By changing NaC1 concentration of the aqueous DNA solution, the CST at each NaC1 concentration was observed. A critical strain rate where CST occurs increased linearly with NaC1 concentration. These facts indicate that the DNA molecule was electrically neutralized by Na^+ ions gradually and simultaneously whole through the molecule.
The regulation of the conformational transition by the elongational flow field was not realized because of the limit of the strain rate generated by the present flow generator. By improving the apparatus, we will retry the experiment.
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