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Institution

Nagoya Institute of Technology

EducationNagoya, Japan
About: Nagoya Institute of Technology is a education organization based out in Nagoya, Japan. It is known for research contribution in the topics: Thin film & Turbulence. The organization has 10766 authors who have published 19140 publications receiving 255696 citations. The organization is also known as: Nagoya Kōgyō Daigaku & Nitech.


Papers
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Journal ArticleDOI
TL;DR: The sources of an absorption band at ∼5 eV observed in SiO 2 :GeO 2 and GeO 2 glasses have not been unambiguously identified but results reported here are consistent with the source of two types of neutral oxygen vacancies.
Abstract: The sources of an absorption band at \ensuremath{\sim}5 eV observed in ${\mathrm{SiO}}_{2}$:${\mathrm{GeO}}_{2}$ and ${\mathrm{GeO}}_{2}$ glasses have not been unambiguously identified. Results reported here are consistent with the source of two types of neutral oxygen vacancies. Samples of ${95\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$:${5\mathrm{G}\mathrm{e}\mathrm{O}}_{2}$ and ${90\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$:${10\mathrm{G}\mathrm{e}\mathrm{O}}_{2}$ were prepared by a chemical vapor deposition soot-remelting method. Optical-absorption and electron paramagnetic resonance spectra were measured. An absorption band centered at 5 eV in as-prepared ${\mathrm{SiO}}_{2}$:${\mathrm{GeO}}_{2}$ glasses is composed of two components. One has a peak at 5.06 eV and a FWHM (full width at half maximum) of 0.38 eV. Illumination with uv light bleached this band, and generated Ge E' centers. A linear relation was found between the decrement in the intensity of the 5.06-eV component and the concentrations of uv-induced Ge E' centers. This relation is a basis for attributing the defect responsible for this component to the precursors of uv-induced Ge E' centers. We propose that the 5.06-eV band is due to neutral oxygen monovacancies (NOV's) coordinated by two Ge ions. The oscillator strength of this band was evaluated to be approximately 0.4\ifmmode\pm\else\textpm\fi{}0.1 assuming that the NOV's are converted into Ge E' centers by absorption of uv quanta. The activation energy for this conversion process was of the order of ${10}^{\mathrm{\ensuremath{-}}2}$ eV.The second component of the absorption spectra has a peak at 5.16 eV and a FWHM of 0.48 eV. This band is not bleached but emits luminescence bands at 3.2 eV (intense) and 4.3 eV (weak) when irradiated with 5-eV light. Based on other research, we assign this band to ${\mathrm{Ge}}^{2+}$ ions coordinated by two oxygens and having two lone pair electrons (neutral oxygen divacancies). The concentrations of ${\mathrm{Ge}}^{2+}$ ions were much larger than those of the NOV's and the ratio of the NOV's to ${\mathrm{Ge}}^{2+}$ ions increases with increasing ${\mathrm{GeO}}_{2}$ content. A similarity was found in the characteristics of these two types of oxygen-deficient defects to those in ${\mathrm{SiO}}_{2}$ glasses.

301 citations

Proceedings ArticleDOI
15 Mar 1999
TL;DR: A hidden Markov model based on multi-space probability distribution (MSD) can model pitch patterns without heuristic assumption and a reestimation algorithm is derived that can find a critical point of the likelihood function.
Abstract: This paper discusses a hidden Markov model (HMM) based on multi-space probability distribution (MSD). The HMMs are widely-used statistical models to characterize the sequence of speech spectra and have successfully been applied to speech recognition systems. From these facts, it is considered that the HMM is useful for modeling pitch patterns of speech. However, we cannot apply the conventional discrete or continuous HMMs to pitch pattern modeling since the observation sequence of the pitch pattern is composed of one-dimensional continuous values and a discrete symbol which represents "unvoiced". MSD-HMM includes discrete HMMs and continuous mixture HMMs as special cases, and further can model the sequence of observation vectors with variable dimension including zero-dimensional observations, i.e., discrete symbols. As a result, MSD-HMMs can model pitch patterns without heuristic assumption. We derive a reestimation algorithm for the extended HMM and show that it can find a critical point of the likelihood function.

296 citations

Journal ArticleDOI
TL;DR: High-speed atomic force microscopy is used to visualize dynamic changes in stimulated proteins and confirms that high-resolution visualization is a powerful approach for studying elaborate biomolecular processes under realistic conditions.
Abstract: Dynamic changes in protein conformation in response to external stimuli are important in biological processes, but it has proved difficult to directly visualize such structural changes under physiological conditions1,2,3,4,5,6,7,8,9,10. Here, we show that high-speed atomic force microscopy7 can be used to visualize dynamic changes in stimulated proteins. High-resolution movies of a light-driven proton pump, bacteriorhodopsin11,12, reveal that, upon illumination, a cytoplasmic portion of each bacteriorhodopsin monomer is brought into contact with adjacent trimers. The bacteriorhodopsin–bacteriorhodopsin interaction in the transiently formed assembly engenders both positive and negative cooperative effects in the decay kinetics as the initial bacteriorhodopsin recovers and, as a consequence, the turnover rate of the photocycle is maintained constant, on average, irrespective of the light intensity. These results confirm that high-resolution visualization is a powerful approach for studying elaborate biomolecular processes under realistic conditions. Dynamic changes in the light-driven proton pump, bacteriorhodopsin, which occur on stimulation with light, can be visualized using high-speed atomic force microscopy.

283 citations

Journal ArticleDOI
TL;DR: In this paper, the authors discuss recent developments in the enantioselective trifluoromethylation reactions, including nucleophilic, electrophilic, and radical approaches.
Abstract: Fluorinated organic compounds have received considerable attention because they possess unique properties such as greater stability, higher electronegativity, and water and oil repellency, which are potentially beneficial in terms of the development of novel pharmaceutical agents and advanced materials. Such extreme behaviors of fluoro-organic compounds however, often make their syntheses all the more complicated, especially when the synthesis of target compounds requires an enantiocontrolled methodology. Many strategies can be employed for introducing chirality into organic molecules, but enantioselective fluorination and trifluoromethylation reactions are especially attractive because non-fluorinated prochiral substrates can be directly transformed to chiral fluoro-organic compounds with a control of absolute configuration. Significant progress has been made in the development of the asymmetric fluorination reaction in recent years; however, the direct enantioselective trifluoromethylation reaction remains a challenge. In this report, we discuss recent developments in the enantioselective trifluoromethylation reactions, including nucleophilic, electrophilic, and radical approaches. Although the emphasis of this report is on the enantioselective trifluoromethylation reaction, the less-studied enantioselective difluoromethylation and monofluoromethylation reactions are also covered.

275 citations


Authors

Showing all 10804 results

NameH-indexPapersCitations
Luis M. Liz-Marzán13261661684
Hideo Hosono1281549100279
Shunichi Fukuzumi111125652764
Andrzej Cichocki9795241471
Kwok-Hung Chan9140644315
Kimoon Kim9041235394
Alex Martin8840636063
Manijeh Razeghi82104025574
Yuichi Ikuhara7597424224
Richard J. Cogdell7348023866
Masaaki Tanaka7186022443
Kiyotomi Kaneda6537813337
Yulin Deng6464116148
Motoo Shiro6472017786
Norio Shibata6357414469
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202316
202272
2021631
2020718
2019701
2018764