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Hideki Shirakawa

Other affiliations: Ritsumeikan University
Bio: Hideki Shirakawa is an academic researcher from University of Tsukuba. The author has contributed to research in topics: Polyacetylene & Liquid crystal. The author has an hindex of 39, co-authored 235 publications receiving 7355 citations. Previous affiliations of Hideki Shirakawa include Ritsumeikan University.


Papers
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Journal ArticleDOI
TL;DR: This lecture is not directly related to the discovery and development of conducting polymers to which the Nobel Prize in Chemistry 2000 was awarded, but the previous work that was carried out just before the discovery of chemical doping is presented.
Abstract: This lecture is not directly related to our discovery and development of conducting polymers to which the Nobel Prize in Chemistry 2000 was awarded. However, I would like to present my previous work that I had carried out just before we reached the discovery of chemical doping. I hope that this will be of use and deepen your understandings by learning what had happened before and how we reached the idea of chemical doping.

612 citations

Journal ArticleDOI
TL;DR: It is now apparent that signal transduction at fertilization is dependent on sperm-stimulated activation of phospholipase C which causes hydrolysis of phosphatidylinositol bisphosphate and production of InsP3, leading to IICR.

525 citations

Journal ArticleDOI
10 Jul 1992-Science
TL;DR: The results indicate that Ca2+ release in fertilized hamster eggs is mediated solely by the IP3 receptor, and Ca(2+)-sensitized IICR, but not CICR generates Ca 2+ waves and Ca2- oscillations.
Abstract: The concentration of cytoplasmic free calcium (Ca2+) increases in various stimulated cells in a wave (Ca2+ wave) and in periodic transients (Ca2+ oscillations). These phenomena are explained by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release (IICR) and Ca(2+)-induced Ca2+ release (CICR) from separate intracellular stores, but decisive evidence is lacking. A monoclonal antibody to the IP3 receptor inhibited both IICR and CICR upon injection of IP3 and Ca2+ into hamster eggs, respectively. The antibody completely blocked sperm-induced Ca2+ waves and Ca2+ oscillations. The results indicate that Ca2+ release in fertilized hamster eggs is mediated solely by the IP3 receptor, and Ca(2+)-sensitized IICR, but not CICR, generates Ca2+ waves and Ca2+ oscillations.

489 citations

Journal ArticleDOI
27 Nov 1998-Science
TL;DR: The high electrical conductivities of approximately 1500 to 1800 siemens per centimeter after iodine doping and the chiral helicity of these films may be exploited in electromagnetic and optical applications.
Abstract: Helical polyacetylene was synthesized under an asymmetric reaction field consisting of chiral nematic (N*) liquid crystals (LCs). The chiral nematic LC was prepared by adding a chiroptical binaphthol derivative as a chiral dopant to a mixture of two nematic LCs. Acetylene polymerizations were carried out using the catalyst titanium tetra-n-butoxide-triethylaluminum dissolved in the chiral nematic LC solvent. The polyacetylene film was shown by scanning electron microscopy to consist of clockwise or counterclockwise helical structure of fibrils. A Cotton effect was observed in the region of the pi --> pi* transition of the polyacetylene chain in circular dichroism spectra. The high electrical conductivities of approximately 1500 to 1800 siemens per centimeter after iodine doping and the chiral helicity of these films may be exploited in electromagnetic and optical applications.

350 citations

Journal ArticleDOI
TL;DR: In this article, the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, was studied in terms of a model of the doping process based on charge transfer.
Abstract: A study of the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, is reported. When films of trans‐ (CH)x are exposed to chlorine, bromine, or iodine vapor, uptake of halogen occurs; and the conductivity increases markedly, over eleven orders of magnitude in the case of iodine. The behavior of the halogenated polyacetylene is like that of a series of semiconductors with activation energies which vary with halogen content. The results are discussed in terms of a model of the doping process based on charge transfer.

335 citations


Cited by
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Journal ArticleDOI
28 Jan 1993-Nature
TL;DR: Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle.
Abstract: Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

6,389 citations

Journal ArticleDOI
TL;DR: The universality of calcium as an intracellular messenger depends on its enormous versatility, which is exploited to control processes as diverse as fertilization, proliferation, development, learning and memory, contraction and secretion.
Abstract: The universality of calcium as an intracellular messenger depends on its enormous versatility. Cells have a calcium signalling toolkit with many components that can be mixed and matched to create a wide range of spatial and temporal signals. This versatility is exploited to control processes as diverse as fertilization, proliferation, development, learning and memory, contraction and secretion, and must be accomplished within the context of calcium being highly toxic. Exceeding its normal spatial and temporal boundaries can result in cell death through both necrosis and apoptosis.

5,369 citations

Journal ArticleDOI
TL;DR: In this paper, the development in the field of coordination polymers or metal-organic coordination networks, MOCNs (metal-organic frameworks, MOFs) is assessed in terms of property investigations in the areas of catalysis, chirality, conductivity, luminescence, magnetism, spin-transition (spin-crossover), nonlinear optics (NLO) and porosity or zeolitic behavior upon which potential applications could be based.
Abstract: The development in the field of coordination polymers or metal-organic coordination networks, MOCNs (metal-organic frameworks, MOFs) is assessed in terms of property investigations in the areas of catalysis, chirality, conductivity, luminescence, magnetism, spin-transition (spin-crossover), non-linear optics (NLO) and porosity or zeolitic behavior upon which potential applications could be based.

3,117 citations

Journal ArticleDOI
TL;DR: School of Chemistry, Bio21 Institute, University of Melbourne, 30 Flemington Road, Victoria 3010, Australia; School of Materials Science and Engineering, Nanyang Technological University, Nastyang Avenue, Republic of Singapore 639798; Institute of Materials Research and Engineering (IMRE) and the Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore 117602.
Abstract: A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

2,378 citations