2003 Fiscal Year Annual Research Report

高周波電磁場・強磁場に対するDNAの電気伝導特性の研究

Research Project

Project/Area Number	15654045
Research Institution	The University of Tokyo
Principal Investigator	前田京剛東京大学, 大学院・総合文化研究科, 助教授 (70183605)
Co-Investigator(Kenkyū-buntansha)	北野晴久東京大学, 大学院・総合文化研究科, 助手 (00313164)
Keywords	電磁波と生体 / DNA / 電気伝導度 / 非接触 / マイクロ波 / ホッピング伝導 / 誘電率 / 粉末試料
Research Abstract	生体の電磁場に対する影響に関する科学的なデータを蓄積する第一歩として,サケの精子から抽出したDNAの10GHzにおける電気伝導度を測定することに成功した。この実験にあたり,以下の点に配慮した。すなわち,DNAの電気伝導度に対するこれまでの測定で結果が収束しないことの理由として,(1)DNAと電極とのオーミックコンタクト(2)DNA分子に対するディスオーダーの影響(3)DNA分子に対する湿度の影響などが挙げられ,問題になっていた。そこで,本研究では,(a)電極に関する一切の問題をなくするために,非接触の方法を選択し,(b)湿度や水の影響を極力排除するために,試料を真空中に封入し電気伝導度測定を行った。このため,われわれのグループが開発した,マイクロ波を用いて粉末の電気伝導度を求める手法を適用した。その結果,10GHzにおいて,明らかに水分子の緩和よりも一桁以上大きな電気伝導度を示すことがわかった。この結果を過去の異なる周波数での測定結果と比べてみることにより,電気伝導度の周波数依存性が,乱れた系が示すホッピング伝導でしばしば見られるべき乗則に従うことがわかった。このことは,虚数部(誘電率)についても成り立つことが推定された。すなわち,マイクロ波領域での誘電率はオーディオ周波数領域の誘電率(やはり実測した)とほとんど変わらず,このことは,電気伝導度の虚数部が周波数にほぼ比例することを示唆している。これらのことから,我々が観測した電気伝導度は,ヌクレオチド分子の重なり方向のパイ結合間のキャリヤのホッピングを見ている可能性があることを示唆している。今後,この伝導度が磁場によってどのように変化するかなどを調べる予定である。

Research Products
(19 results)

All Other

All Publications (19 results)

[Publications] R.Inoue: "Double sphere model in the enclosed cavity perturbation"J.Appl.Phys.. 93. 2736-2745 (2003)
[Publications] A.Maeda: "Sliding conduction by the quasi one-dimentional charge-ordered state in SR_<14-x>Ca_xCu_<24>O_<41+δ>"Physical Review B. 67. 115115-115119 (2003)
[Publications] K.Kinoshita: "Millimeter wave and microwave electrodynamic spectroscopy of YBa_2(Cu_<1-x>Zn_x)_3O_y in the Meissner and mixed state"Physica C. 388-389. 417-418 (2003)
[Publications] H.Kitano: "Nonlinear conductivity in the slightly hole-doped Sr_<14-x>Ca_xCu_<24>O_<41> ladder compounds"Physica C. 388-389. 231-232 (2003)
[Publications] K.Iwaya: "Electronic state of NbSe_2 investigated by STM/STS"Physica B. 329-333. 1598-1599 (2003)
[Publications] A.Maeda: "Dynamic phase diagram of vortices in high-Tc superconductors determined by experimental studies"Physica B. 329-333. 1346-1347 (2003)
[Publications] R.Inoue: "The inverse analysis of the enclosed cavity perturbation technique"Physica B. 329-333. 1546-1547 (2003)
[Publications] Y.Togawa: "Dynamic phase diagram of driven vortices in Bi_2Sr_2CaCu_2O_y"J.Low Temp.Phys.. 131. 907-911 (2003)
[Publications] H.Kitano: "Microwave conductivity of superconducting and insulating fullerides"J.Low Temp.Phys. 131. 1251-1258 (2003)
[Publications] A.Maeda: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"J.Low Temp.Phys. 131. 969-973 (2003)
[Publications] Y.Iwasa: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"Physica B. 388-389. 615-616 (2003)
[Publications] T.Hanaguri: "An instrument for low-and variable-temperature-wave surface impedance"Rev.Sci.Instrum. 74. 4436-4441 (2003)
[Publications] A.Maeda: "Study of kinetic friction of solid using driven lattice of quantized vortex in high-temperature superconductors -a new route to study microscopic tribology"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
[Publications] K.Kinoshita: "Impurity effect on the electronic state of the vortex core in the mixed state of Yba_2Cu_3O_y"Physica C. (in press).
[Publications] H.Kitano: "Frequency dependent microwave conductivity of La_<2-x>Sr_xCuO_4 thin films"Physica C. (in press).
[Publications] H.Kitano: "Microwave conductivity of fullerene intercalation compounds : Mott transition driven by the orthorhombic distortion"Proc.Fullerenes, Nanotubes, and Carbon Nanoclusters Symposia, France.2003. 469-473 (2003)
[Publications] R.Inoue: "A nondestructive method of measureing dielectric properties of substrate at microwave and millimeter-wave frequencies using an open-ended coaxial resonator probe"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
[Publications] R.Inoue: "Investigation of a new technique to measure large dielectric constant at microwave frequencies using the enclosed cavity perturbation method"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).
[Publications] R.Inoue: "Geometrical factors in the measurement of high temperature superconductors by the enclosed cavity perturbation technique"Proc.of 2003 Asia-Pacific Microwave Conference(APMC'03),Seoul, extended abstract. 3. 2040-2043 (2003)

2003 Fiscal Year Annual Research Report

高周波電磁場・強磁場に対するDNAの電気伝導特性の研究

Principal Investigator

前田 京剛 東京大学, 大学院・総合文化研究科, 助教授 (70183605)

Research Products

[Publications] R.Inoue: "Double sphere model in the enclosed cavity perturbation"J.Appl.Phys.. 93. 2736-2745 (2003)

[Publications] A.Maeda: "Sliding conduction by the quasi one-dimentional charge-ordered state in SR_<14-x>Ca_xCu_<24>O_<41+δ>"Physical Review B. 67. 115115-115119 (2003)

[Publications] K.Kinoshita: "Millimeter wave and microwave electrodynamic spectroscopy of YBa_2(Cu_<1-x>Zn_x)_3O_y in the Meissner and mixed state"Physica C. 388-389. 417-418 (2003)

[Publications] H.Kitano: "Nonlinear conductivity in the slightly hole-doped Sr_<14-x>Ca_xCu_<24>O_<41> ladder compounds"Physica C. 388-389. 231-232 (2003)

[Publications] K.Iwaya: "Electronic state of NbSe_2 investigated by STM/STS"Physica B. 329-333. 1598-1599 (2003)

[Publications] A.Maeda: "Dynamic phase diagram of vortices in high-Tc superconductors determined by experimental studies"Physica B. 329-333. 1346-1347 (2003)

[Publications] R.Inoue: "The inverse analysis of the enclosed cavity perturbation technique"Physica B. 329-333. 1546-1547 (2003)

[Publications] Y.Togawa: "Dynamic phase diagram of driven vortices in Bi_2Sr_2CaCu_2O_y"J.Low Temp.Phys.. 131. 907-911 (2003)

[Publications] H.Kitano: "Microwave conductivity of superconducting and insulating fullerides"J.Low Temp.Phys. 131. 1251-1258 (2003)

[Publications] A.Maeda: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"J.Low Temp.Phys. 131. 969-973 (2003)

[Publications] Y.Iwasa: "Effect of impurities on the electronic structure of vortex core investigated by microwave surface impedance measurement"Physica B. 388-389. 615-616 (2003)

[Publications] T.Hanaguri: "An instrument for low-and variable-temperature-wave surface impedance"Rev.Sci.Instrum. 74. 4436-4441 (2003)

[Publications] A.Maeda: "Study of kinetic friction of solid using driven lattice of quantized vortex in high-temperature superconductors -a new route to study microscopic tribology"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).

[Publications] K.Kinoshita: "Impurity effect on the electronic state of the vortex core in the mixed state of Yba_2Cu_3O_y"Physica C. (in press).

[Publications] H.Kitano: "Frequency dependent microwave conductivity of La_<2-x>Sr_xCuO_4 thin films"Physica C. (in press).

[Publications] H.Kitano: "Microwave conductivity of fullerene intercalation compounds : Mott transition driven by the orthorhombic distortion"Proc.Fullerenes, Nanotubes, and Carbon Nanoclusters Symposia, France.2003. 469-473 (2003)

[Publications] R.Inoue: "A nondestructive method of measureing dielectric properties of substrate at microwave and millimeter-wave frequencies using an open-ended coaxial resonator probe"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).

[Publications] R.Inoue: "Investigation of a new technique to measure large dielectric constant at microwave frequencies using the enclosed cavity perturbation method"Proc.1^<st> Meeting on Applied Physics, Badajoz, Spain. (in press).

[Publications] R.Inoue: "Geometrical factors in the measurement of high temperature superconductors by the enclosed cavity perturbation technique"Proc.of 2003 Asia-Pacific Microwave Conference(APMC'03),Seoul, extended abstract. 3. 2040-2043 (2003)

前田京剛東京大学, 大学院・総合文化研究科, 助教授 (70183605)