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Numata M.,Kyoto Prefectural University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies | Shinkai S.,Sojo University
Chemical Communications | Year: 2011

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3- glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry. © 2011 The Royal Society of Chemistry. Source

Yasunaga K.,Japan Institute of Systems, Information Technologies and Nanotechnologies
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In a public-key encryption scheme, if a sender is not concerned about the security of a message and is unwilling to generate costly randomness, the security of the encrypted message can be compromised. This is caused by the laziness of the sender. In this work, we characterize lazy parties in cryptography. Lazy parties are regarded as honest parties in a protocol, but they are not concerned about the security of the protocol in a certain situation. In such a situation, they behave in an honest-looking way, and are unwilling to do a costly task. We study, in particular, public-key encryption with lazy parties. Specifically, as the first step toward understanding the behavior of lazy parties in public-key encryption, we consider a rather simple setting in which the costly task is to generate randomness used in algorithms, and parties can choose either costly good randomness or cheap bad randomness. We model lazy parties as rational players who behaves rationally to maximize their utilities, and define a security game between lazy parties and an adversary. A secure encryption scheme requires that the game is conducted by lazy parties in a secure way if they follow a prescribed strategy, and the prescribed strategy is a good equilibrium solution for the game. Since a standard secure encryption scheme does not work for lazy parties, we present some public-key encryption schemes that are secure for lazy parties. © 2012 Springer-Verlag. Source

Hirata S.,Kyushu University | Kubota K.,Kyushu University | Jung H.H.,Kyushu University | Hirata O.,Nissan Chemical Industries Ltd. | And 3 more authors.
Advanced Materials | Year: 2011

Organic light-emitting diodes containing a liquid emitting layer that exhibit improved external electroluminescence quantum efficiency (Î∥EL) and maximum luminance are presented. Doping the liquid emitting layer with an electrolyte significantly decreases the turn-on voltage for electroluminescence. Insertion of a TiO2 hole-blocking layer between the liquid emitting layer and indium tin oxide cathode improves Î∥EL. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Tamesue S.,Osaka University | Takashima Y.,Osaka University | Yamaguchi H.,Osaka University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2010

Shine a light: A supramolecular hydrogel is formed by the glucan curdlan equipped with α-cyclodextrins (CD-CUR) and azobenzene-modified poly(acrylic acid)(pAC12Azo). The sol-gel transition and the morphology of the supramolecular hydrogel can be switched by photoirradiation at the appropriate wavelength, which controls the formation of an inclusion complex between the α-cyclodextrins and the azobenzene moieties (see picture). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Sobczuk A.A.,Sojo University | Tamaru S.-I.,Sojo University | Shinkai S.,Sojo University | Shinkai S.,Japan Institute of Systems, Information Technologies and Nanotechnologies
Chemical Communications | Year: 2011

A new functional low molecular-weight gelator (LMWG) based on crown-appended quaterthiophene was synthesized and investigated as a new alkali metal cation responsive material with enhanced fluorescence emission upon gel-to-sol phase transition. © 2011 The Royal Society of Chemistry. Source

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