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Tokyo, Japan

Tokyo University of Technology is a private university in Hachiōji, Tokyo, Japan. The predecessor of the school was founded in May 1947. After becoming a vocational school in 1953, it was chartered as a university in 1986. Wikipedia.

Yamamoto H.,Tokyo University of Technology
Proceedings of SPIE - The International Society for Optical Engineering

Application of white LEDs is extended toward high-output light sources, e.g. for automotive headlights, and better spectral matching with optical filters for LCD backlighting. To meet such new demands, phosphor materials have been investigated with focus on their luminescence spectra, temperature characteristics and reliability. The conventional yellow phosphor based on Y3Al5O12:Ce3+ has excellent performance as a single phosphor combined with a blue LED. More recently developed nitrido- or oxonitrido-silicates activated with Eu2+ are also promising materials showing green to red luminescence depending on a composition and high thermal and chemical stability. And yet, demands for specific application have been made clear and strong. This paper reviews the present status and challenging goals of phosphors in the next stage further to make progress in white LEDs. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

Lee S.K.,Korea Institute of Energy Research | Mogi G.,Tokyo University of Technology | Hui K.S.,City University of Hong Kong
Renewable and Sustainable Energy Reviews

The Low Carbon, Green Growth was declared as Korean national agenda in 2008. Korea has been enhancing the green growth for the sustainable economic development and fostering energy. To improve Korean national energy security and promote the Low Carbon, Green Growth, we established a long term strategic energy technology roadmap. In this paper, five criteria, such as economical impact, commercial potential, inner capacity, technical spin-off, and development cost, were used to assess the strategic energy technologies against high oil prices. We developed the integrated two-stage multi-criteria decision making (MCDM) approach which was used to evaluate the relative weights of criteria and measures the relative efficiency of energy technologies against high oil prices. On the first stage, the fuzzy analytic hierarchy process, reflecting the vagueness of human thought with interval values instead of crisp numbers, allocated the relative weights of criteria effectively instead of the AHP approach. On the second stage, the data envelopment analysis approach measured the relative efficiency of energy technologies against high oil prices with economic viewpoints. The relative efficiency score of energy technologies against high oil prices can be the fundamental decision making data which help decision markers to effectively allocate the limited R&D resources. © 2013 Elsevier Ltd. Source

Yoshimura T.,Tokyo University of Technology
Journal of Lightwave Technology

Using the finite-difference time-domain method, we simulated the growth of self-organized waveguides between a 3-μm-wide micro-scale waveguide and a 600-nm-wide nano-scale waveguide, which has a luminescent target on its core edge. The two waveguides are placed together, with gap sizes ranging from 16 to 64 μm, in a photo-induced refractive-index increase-type material. When a 400 nm wavelength write beam is introduced from the micro-scale waveguide, luminescence is generated by the luminescent target. A waveguide is then gradually self-organized between the two waveguides, even when a lateral misalignment of 600 nm exists between them, and provides a self-aligned optical coupling with a coupling loss of 1.5-1.8 dB. This indicates that the self-organized waveguide can be used as an optical solder to connect a micro-scale waveguide in a multi-chip module or printed circuit board to a nano-scale waveguide in a large-scale integrated circuit. The optimum writing time required to attain the minimum coupling loss increases with increasing lateral misalignment. The dependence of the optimum writing time on the misalignment is reduced with increasing gap distance, and the dependence almost vanishes when the gap distance is 64 μm, thus enabling unmonitored optical solder formation. © 1983-2012 IEEE. Source

Nakamura H.,Tokyo University of Technology
Analytical Methods

Rapid economic growth in Japan resulted in serious organic pollution in the 1960s. In contrast, recent organic pollution is caused primarily by phosphorus-based anthropogenic eutrophication, which also induces heavy metal pollution. In the present review, causes of the recent organic pollution are briefly introduced, and our approaches, based on studies of environmental water biosensing methods as tools for estimating the degrees of the recent organic pollution, eutrophication, and heavy metal pollution, are introduced. © The Royal Society of Chemistry 2010. Source

Multi-electrode arrays (MEAs) can be used for noninvasive, real-time, and long-term recording of electrophysiological activity and changes in the extracellular chemical microenvironment. Neural network organization, neuronal excitability, synaptic and phenotypic plasticity, and drug responses may be monitored by MEAs, but it is still difficult to measure presynaptic activity, such as neurotransmitter release, from the presynaptic bouton. In this study, we describe the development of planar carbon nanotube (CNT)-MEA chips that can measure both the release of the neurotransmitter dopamine as well as electrophysiological responses such as field postsynaptic potentials (fPSPs) and action potentials (APs). These CNT-MEA chips were fabricated by electroplating the indium-tin oxide (ITO) microelectrode surfaces. The CNT-plated ITO electrode exhibited electrochemical response, having much higher current density compared with the bare ITO electrode. Chronoamperometric measurements using these CNT-MEA chips detected dopamine at nanomolar concentrations. By placing mouse striatal brain slices on the CNT-MEA chip, we successfully measured synaptic dopamine release from spontaneous firings with a high S/N ratio of 62. Furthermore, APs and fPSPs were measured from cultured hippocampal neurons and slices with high temporal resolution and a 100-fold greater S/N ratio. Our CNT-MEA chips made it possible to measure neurotransmitter dopamine (presynaptic activities), postsynaptic potentials, and action potentials, which have a central role in information processing in the neuronal network. CNT-MEA chips could prove useful for in vitro studies of stem cell differentiation, drug screening and toxicity, synaptic plasticity, and pathogenic processes involved in epilepsy, stroke, and neurodegenerative diseases. Copyright © 2013 Elsevier B.V. All rights reserved. Source

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