Time filter

Source Type

Nishikiori H.,Shinshu University | Tanigaki T.,Shinshu University | Endo M.,Shinshu University | Fujii T.,Nagano Prefectural Institute of Technology

Acidic functional groups produced on the surface of acid-treated multi-walled carbon nanotubes (MWCNTs) were quantified by fluorescence measurements using 1-aminopyrene (1-AP) as an in situ probe molecule. The 1-AP cation-like bands were observed on the HNO3/H2SO 4 mixture-treated MWCNT surfaces because the 1-AP molecule was tightly immobilized by the hydrogen bonding interaction between its amino group and the Brönsted-acidic groups on the MWCNT surface. The fluorescence measurement allowed us to confirm the Langmuir-type adsorption of 1-AP on the functional groups of the MWCNTs, and estimate their amount of the functional groups and adsorption equilibrium constant. A longer acid treatment caused the chemical modification to generate higher amounts of the Brönsted-acidic functional groups and improve the adsorption ability on the MWCNT surface. About 2% of carbon in the MWCNTs was oxidized by the 24 h acid treatment. This value corresponded to 15-22% of carbon in the surface layer. © 2013 Elsevier Ltd. All rights reserved. Source

Nishikiori H.,Shinshu University | Hashiguchi S.,Shinshu University | Ito M.,Shinshu University | Setiawan R.A.,Shinshu University | Fujii T.,Nagano Prefectural Institute of Technology
Applied Catalysis B: Environmental

Allophane-titania nanocomposite electrodes for photofuel cells were prepared from titanium alkoxide sols dispersing the natural clay mineral allophane. The electrochemical measurements indicated that the oxidative degradation of starch in the solutions and suspensions enhanced the generation of electricity during UV irradiation. CO2 was observed as the degradation product. A higher photocurrent was observed using the allophane-titania nanocomposite electrode adsorbing a greater amount of the starch molecules. Allophane increased the capacity of the electrode to adsorb the starch molecules, even from the suspensions. This brought the molecules close to the titania nanoparticles, on which their oxidation induced the generation of electricity. © 2013 Elsevier B.V. Source

Nakamura K.,Nagano Prefectural Institute of Technology
Journal of the Physical Society of Japan

We study the Pancharatnam-Berry geometric phase for polarized light beams of a non-closed cycle on the Poincare sphere. A geometric phase in different states of polarization is of great importance. It is shown that the Pancharatnam in-phase transformation can be regarded as a transformation of basis vectors. Using spherical trigonometry, we provide a new concise method of proving the Pancharatnam theorem. © 2013 The Physical Society of Japan. Source

Ota T.,Nagano Prefectural Institute of Technology | Morita H.,University of Electro - Communications
IEEE International Symposium on Information Theory - Proceedings

Lossless data compression via substring enumeration (CSE) has been proposed by Dubé and Beaudoin in 2010. The CSE outputs its encoder called compacted substring automaton as a codeword, and an efficient representation of the automaton is also proposed. In this paper, we prove an isomorphism between compacted substring automaton and antidictionary automaton, which is an encoder of antidictionary coding. Then we propose a new static antidictionary coding which uses the representation of compacted substring automaton instead of antidictionary. Moreover, we prove an asymptotic optimality of the proposed coding for a stationary ergodic source. © 2013 IEEE. Source

Ota T.,Nagano Prefectural Institute of Technology | Morita H.,University of Electro - Communications
IEICE Transactions on Information and Systems

An antidictionary is particularly useful for data compression, and on-line electrocardiogram (ECG) lossless compression algorithms using antidictionaries have been proposed. They work in real-time with constant memory and give better compression ratios than traditional lossless data compression algorithms, while they only deal with ECG data on a binary alphabet. This paper proposes on-line ECG lossless compression for a given data on a finite alphabet. The proposed algorithm gives not only better compression ratios than those algorithms but also uses less computational space than they do. Moreover, the proposed algorithm work in real-time. Its effectiveness is demonstrated by simulation results. Copyright © 2010. Source

Discover hidden collaborations