Second-order Nonlinear Optical Microscopy of Spider Silk

Asymmetric $\rm \beta$-sheet protein structures in spider silk should induce nonlinear optical interaction such as second harmonic generation (SHG) which is experimentally observed for a radial line and dragline spider silk by using an imaging femtosecond laser SHG microscope. By comparing different spider silks, we found that the SHG signal correlates with the existence of the protein $\rm \beta$-sheets. Measurements of the polarization dependence of SHG from the dragline indicated that the $\rm \beta$-sheet has a nonlinear response depending on the direction of the incident electric field. We propose a model of what orientation the $\rm \beta$-sheet takes in spider silk.Comment: 8 pages, 8 figures, 1 tabl

Sum frequency generation spectroscopy of the attachment disc of a spider

The pyriform silk of the attachment disc of a spider was studied using infrared-visible vibrational sum frequency generation (SFG) spectroscopy. The spider can attach dragline and radial lines to many kinds of substrates in nature (concrete, alloy, metal, glass, plant branches, leaves, etc.) with the attachment disc. The adhesion can bear the spider's own weight, and resist the wind on its orb web. From our SFG spectroscopy study, the NH group of arginine side chain and/or NH$_{2}$ group of arginine and glutamine side chain in the amino acid sequence of the attachment silk proteins are suggested to be oriented in the disc. It was inferred from the observed doublet SFG peaks at around 3300 cm$^{-1}$ that the oriented peptide contains two kinds of structures.Comment: 21 pages, 8 figure

Ecological traits and their diversities of five Zostera marina populations in and around Hiroshima Bay, the Seto Inland Sea, Japan

広島湾および周辺海域の5カ所の生育地のアマモZostera marinaの生態的特性を2004年の繁茂期に調査した。調査場所は広島湾奥部の阿品（St.1），同湾央部の大黒神島（St.2），同湾口部の屋代島（St.3），柳井湾奥部の伊保庄（St.4），および同湾外部に位置する平郡島（St.5）である。アマモの分布水深は生育地により異なり，St.1，St.2では海底でのアオサ類等の堆積により，分布下限水深は1-2m（C.D.L. 基準）までである一方，他の生育地では4-6mまで分布した。アマモの平均現存量は120-180g DWm-2の範囲にあったが，アマモの株のサイズと密度は生育地により異なっていた。平均株密度は生育地により88-278 shoots m-2の範囲であり，St.3およびSt.5では特に浅所で小型の株が密生した。これらの群落では，総現存量に占める地下部現存量の割合が相対的に大きかった。一方，湾奥部に位置するSt.1とSt.4では，アマモの株は大型である一方生育密度は低かった。群落内の底質の粒度組成の相違から，波浪流動等の物理的環境が生育地間で異なることが示唆され，それぞれの場所のアマモの生態的特性はその影響を受けていると考えられた。Ecological traits of five Zostera marina populations in and around Hiroshima Bay were investigated in a luxuriant season of 2004. Study sites were located at the most inner (Ajina; St.1), center (O-kurokami-jima; St. 2) and near the mouth area (northern coast of Yahiro-jima; St. 3) of Hiroshima Bay, and at the inner area (Ihono-sho; St. 4) and the outside (Heigun-jima; St.5) of Yanai Bay which is the strait adjacent to Hiroshima Bay. The distribution depth (C.D.L.) was different among the populations. The lower depth of Zostera distribution was limited to 1-2 m at St.1 and 2 by algal-mat of Ulva spp. and other macroalgae, though it was 4-6 m at St. 3-5. Mean biomass was ranged in 120-180g DWm-2, but shoot size and density was different among the populations. Mean density ranged between 88-278 shoots m-2, and the populations at St.3 and 5 exhibited higher densities with smaller shoots especially in shallow stands of the two population. These stands also exhibited higher proportion of below-ground biomass to total biomass. On the contrary, populations in inner areas (St. 1 and 4) exhibited lower density with larger shoots. Physical conditions such as water motion induced by waves were different among the habitats which were shown in grain size compositions of the sediments, and this could affect the ecological traits of each Z. marina population.本調査は，水産庁委託「生物多様性に配慮したアマモ場造成技術開発調査事業」（平成16～18年度）の一環として実施されたものである

Success of Life Based on Motivation Behavior : Case Study between Japanese students and Asian students at JAIST

北陸先端科学技術大学院大学　21世紀COE プログラム「知識科学に基づく科学技術の創造と実践

Absolute second order nonlinear susceptibility of Pt nanowire arrays on MgO faceted substrates with various cross-sectional shapes

We have measured optical second harmonic generation (SHG) intensity from three types of Pt nanowires with 7 nm widths of elliptical and boomerang cross-sectional shapes, and with 2 nm width elliptical cross-sectional shapes on the MgO faceted templates. From the SHG intensities, we calculated the absolute value of the nonlinear susceptibility χ^(2) integrated in the direction of the wire-layer thickness. The tentatively obtained bulk χ^(2)B of the wire layer was very large, approaching the value of the well-known nonlinear optical material BaTiO_3

Ab initio calculations of the optical properties of crystalline and liquid InSb

Ab initio calculations of the electronic and optical properties of InSb were performed for both the crystalline and liquid states. Two sets of atomic structure models for liquid InSb at 900 K were obtained by ab initio molecular dynamics simulations. To reduce the effect of structural peculiarities in the liquid models, an averaging of the two sets of the calculated electronic and optical properties corresponding to the two liquid models was performed. The calculated results indicate that, owing to the phase transition from crystal to liquid, the density of states around the Fermi level increases. As a result, the energy band gap opening near the Fermi level disappears. Consequently, the optical properties change from semiconductor to metallic behavior. Namely, owing to the melting of InSb, the interband transition peaks disappear and a Drude-like dispersion is observed in the optical dielectric functions. The optical absorption at a photon energy of 3.06 eV, which is used in Blu-ray Disc systems, increases owing to the melting of InSb. This increase in optical absorption is proposed to result from the increased optical transitions below 2 eV

Metal-Interface Second Harmonic Generation from Pt/Cu Bimetallic Nanowire Arrays on NaCl(110) Faceted Templates

We have obtained the azimuthal angle dependence of the second harmonic (SH) intensity from bimetallic Pt/Cuand Pt/SiO/Cu nanowire arrays. The arrays were fabricated by shadow deposition on NaCl(110) faceted templates.The SH intensity from the Pt/Cu nanowire array measured in S_/S_ polarization combination were 4.7 times larger than that from the Pt/SiO/Cu nanowire array at the fundamental photon energy of 2.33 eV. Phenomenologicalanalysis of the intensity patterns and numerical calculation of the local fields have shown that theinversion symmetry broken at the metal-metal interface is responsible for the enhanced SH generation from thePt/Cu bimetallic nanowire arrays