| POLYMERS Vol.63 No.7 |
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COVER STORY
Origin of Polymer Structure Characterization: Special issue on the occasion of the 2014 International Year of Crystallography（IYCr2014） |
| COVER STORY: Highlight Reviews |
| Pioneer of Crystallography-Drs. Torahiko Terada and Ukichiro Nakaya | Kenzo KANDA |
| <Abstract> A century has passed since a crystal structure was revealed by X-rays. UNESCO decided the year 2014 to memorize this historical discovery as International Year of Crystallography（IYCr2014）. The initial development of X-ray crystallogrphy has been achieved by Dr. Max von Laue, Dr. William Lawrence Bragg, Dr. William Henry Bragg and Dr. Torahiko Terada almost at the same period. Dr. Ukichiro Nakaya who was a student of Dr. Terada develped the science of snow which contributes to the various area of modern science and technology. Both Drs. Terada and Nakaya wrote many essays which attracts many peoples. Keywords: IYCr2014 / X-Ray Crystallography / Torahiko Terada / Ukichiro Nakaya / Snow Crystal |
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| Characteristics of Polymer Crystals | Keisuke KAJI |
| <Abstract> From the viewpoint of higher performance of polymer materials, characteristics of polymer crystals are discussed. After referring not only to important properties of crystals of linear polymers such as melting temperature and crystalline modulus but also to the crystallite size effect on X-ray diffraction, a new concept on the mechanism of melt-crystallization is elucidated. In the induction period of crystallization from a polymer melt the micro-phase separation of either binodal or spinodal type due to the orientation fluctuations of extended segments occurs depending on the crystallization temperature. The binodal crystallization forms the usual spherulites, but the spinodal one results in the formation of many small spherulites. For high-performance polymer materials the spinodal crystallization is important. Keywords: Polymer Crystals / Crystallization Mechanism / Induction Period / Phase Separation / Binodal Crystallization / Spinpdal Crystallization / High Performance Materials |
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| Polymer Crystals and Electron Microscopy | Seiji ISODA |
| <Abstract> Electron microscopy has been an excellent tool to analyse polymer crystal structures in the polymer science history, particularly since the discovery of microscopic polymer single crystals. Their historical contribution is reviewed, and typical recent sophisticated achievements by electron microscopy are described in cases of electron crystallography, high resolution imaging and electron tomography. Finally some future prospects are discussed for the sake of young polymer scientists. Keywords: Polymer Crystals / Electron Microscopy |
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| COVER STORY: Topics and Products |
| Direct Observation of Crystalline Lattices in an Ultrahigh Strength Polymer | Hiroki MURASE |
| <Abstract> PBO fiber is the strongest organic fiber in the world. Direct observation of crystalline lattices was investigated in the PBO fiber using transmission electron microscopy（TEM）. The density fluctuations giving a four-point type scattering on small-angle X-ray scattering（SAXS） have attracted the attention of many researchers. The combination of lattice images and defocused images elucidated the origin of the density fluctuations. The high density regions show a positional coincidence with the lattice fringes in the TEM micrographs and this highly suggests that the intriguing SAXS pattern originates from the density difference between the crystalline regions and the non-crystalline disordered regions. Keywords: Crystalline Lattice / TEM / Lattice Image / Deforcused Image |
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| Most Advanced Structure Analysis of Polymer Crystals Based on Wide-Angle Neutron Diffraction Data | Kohji TASHIRO |
| <Abstract> The most advanced state of crystal structure analysis of polymer substances has been reviewed on the basis of wide-angle neutron diffraction （WAND） data. Several case studies have been used to extract the hydrogen atomic positions in the unit cell, which are indispensable in the most reliable theoretical estimation of ultimate mechanical properties of polymer crystals as a guiding principle to develop the polymer materials with more excellent mechanical properties. These 2D WAND data were collected using a BIX-3 system of JRR-3 and also an i-BIX system of J-PARC, Tokai-mura, Japan. The organized combination of WAND data with high-energy synchrotron wide-angle X-ray diffraction data has been found to give the most accurate crystal structure information as exemplified for the cases of polyoxymethylene and poly（L-lactic acid）. Another utilization of neutron scattering is also pointed out for the studies of molecular motions in the phase transitions, chain aggregation state in the melt, and so on. Keywords: Wide-Angle Neutron Diffraction / Crystal Structure Analysis / Hydrogen Atomic Positions / Ultimate Mechanical Property / High-Energy Synchrotron Wide-Angle X-Ray Diffraction / Polyethylene / Polyoxymethylene / Poly（L-lactic acid） |
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| Capturing Low-Affinity Protein-Protein Interactions in the Regulation of Cellular Signal Transduction by X-Ray Crystallography | Terukazu NOGI |
| <Abstract> Most protein molecules are localized at particular compartments within the cell and their mobilities are more or less restricted due to the molecular crowding effects. For instance, membrane proteins can diffuse only two-dimensionally because they are confined in the lipid bilayer. It is therefore presumed that even low-affinity protein-protein interactions should be effective for regulating physiological functions of membrane proteins whereas they cannot be detected by biochemical binding assays using solubilized protein molecules or fragments. In contrast, X-ray crystallography can be applied to the detection of such weak interactions in some cases since functional oligomeric assemblies or physiologically-relevant superstructures are sometimes reproduced in the crystal packing. The significances of crystal packing interactions can be examined by combining a wide range of structural biology methods including nuclear magnetic resonance, small-angle X-ray scattering, electron and light microscopy. In general, such multidisciplinary approaches are accepted as “integrated structural biology” and are expected to elucidate structures and dynamics of protein molecules in action. Keywords: X-Ray Crystallography / Signal Transduction / Membrane Protein / Protein-Protein Interactions / Integrated Structural Biology |
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| Polymer Science and I: A Personal Account |
| What I like | Miyuki OSHIMURA |
| <Abstract> From when I was assigned to the laboratory until now, my motivation for my study is a “what I like” approach. Spreading my interest, I’ve been broadening my study areas, luckily. |
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| Front-Line Polymer Science |
| Gigantic Enhanced Chiral Photonics | Michiya FUJIKI |
| <Abstract> Circularly polarized electromagnetic wave is currently utilized in several mobile telecommunication systems in 1-12 GHz region, including ETC, GPS, and satellite broadcasting. Recently, several optically active materials and devices have been realized directed toward high-performance circularly polarized absorption, reflectance, and emission modes in UV-visible region. The present review highlights recent developments in gigantic enhanced chiroptical materials and devices operating at UV-visible region. Moreover, this review showed uniqueness of circularly polarized light in the animate nature. Understanding modern chiral photonics and the animated nature are promising in a wide range of circularly-polarized oriented applications, including white-light backlight, laser, nonlinear optics, biosensors, FET, controlled plant growing, elucidation of photosynthesis mechanism, practical absolute chiral photosynthesis, and a possible answer to homochirality question on Earth. Keywords: Circular Dichroism / Circularly Polarized Luminescence / Animated Nature / Telecommunication / Chiral Photonics / Absolute Asymmetric Synthesis / Homochirality / Structural Coloring / Chirality / Helicity |
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