68 research outputs found

    Table_1_Electroencephalogram-Based Single-Trial Detection of Language Expectation Violations in Listening to Speech.XLSX

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    We propose an approach for the detection of language expectation violations that occur in communication. We examined semantic and syntactic violations from electroencephalogram (EEG) when participants listened to spoken sentences. Previous studies have shown that such event-related potential (ERP) components as N400 and the late positivity (P600) are evoked in the auditory where semantic and syntactic anomalies occur. We used this knowledge to detect language expectation violation from single-trial EEGs by machine learning techniques. We recorded the brain activity of 18 participants while they listened to sentences that contained semantic and syntactic anomalies and identified the significant main effects of these anomalies in the ERP components. We also found that a multilayer perceptron achieved 59.5% (semantic) and 57.7% (syntactic) accuracies.</p

    Imbalance between Anion and Cation Distribution at Ice Interface with Liquid Phase in Frozen Electrolyte As Evaluated by Fluorometric Measurements of pH

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    When an aqueous electrolyte is frozen, anions and cations are distributed between liquid and ice phases in different fashions. This partition imbalance is relaxed by the transfer of H+ and OH– to each phase, resulting in the acidification of the liquid phase when the cation is better distributed in the ice phase than the anion and in the basification in the opposite situation. In this work, a pH change in the liquid phase has been precisely evaluated by fluorescence ratiometry with pyranine as the pH probe. For frozen alkali chlorides (LiCl, NaCl, and KCl), the liquid phase is always basified by freezing due to the preferential partition of Cl– over the alkali metal cations. Changes in pH are quantitatively analyzed by a partition model, in which the distribution of an ion between the liquid and ice phases is determined by the partition coefficient. Since the concentration of a salt (i.e., ions) in the liquid phase in contact with ice becomes higher as freezing proceeds, the concentration of the ions in the ice phase is higher near the interface with the liquid phase and decreases toward the interior of ice. When the temperature of a frozen electrolyte increases, the ionic imbalance is relaxed to some extent by melting of ice near the interface

    Supramolecular Hemoprotein Assembly with a Periodic Structure Showing Heme–Heme Exciton Coupling

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    A supramolecular assembly of units of cytochrome <i>b</i><sub>562</sub> with externally attached heme having intermolecular linkages formed via the heme–heme pocket interaction was investigated in an effort to construct a well-defined structure. The engineered site for surface attachment of heme at Cys80 in an N80C mutant of cytochrome <i>b</i><sub>562</sub> provides the primary basis for the formation of the periodic assembly structure, which is characterized herein by circular dichroism (CD) spectroscopy and high-speed atomic force microscopy (AFM). This assembly represents the first example of the observation of a split-type Cotton effect by heme–heme exciton coupling in an artificial hemoprotein assembly system. Molecular dynamics simulations validated by simulated CD spectra, AFM images, and mutation experiments reveal that the assembly has a periodic helical structure with 3 nm pitches, suggesting the formation of the assembled structure is driven not only by the heme–heme pocket interaction but also by additional secondary hydrogen bonding and/or electrostatic interactions at the protein interfaces of the assembly

    Supramolecular Hemoprotein Assembly with a Periodic Structure Showing Heme–Heme Exciton Coupling

    No full text
    A supramolecular assembly of units of cytochrome <i>b</i><sub>562</sub> with externally attached heme having intermolecular linkages formed via the heme–heme pocket interaction was investigated in an effort to construct a well-defined structure. The engineered site for surface attachment of heme at Cys80 in an N80C mutant of cytochrome <i>b</i><sub>562</sub> provides the primary basis for the formation of the periodic assembly structure, which is characterized herein by circular dichroism (CD) spectroscopy and high-speed atomic force microscopy (AFM). This assembly represents the first example of the observation of a split-type Cotton effect by heme–heme exciton coupling in an artificial hemoprotein assembly system. Molecular dynamics simulations validated by simulated CD spectra, AFM images, and mutation experiments reveal that the assembly has a periodic helical structure with 3 nm pitches, suggesting the formation of the assembled structure is driven not only by the heme–heme pocket interaction but also by additional secondary hydrogen bonding and/or electrostatic interactions at the protein interfaces of the assembly

    Supramolecular Hemoprotein Assembly with a Periodic Structure Showing Heme–Heme Exciton Coupling

    No full text
    A supramolecular assembly of units of cytochrome <i>b</i><sub>562</sub> with externally attached heme having intermolecular linkages formed via the heme–heme pocket interaction was investigated in an effort to construct a well-defined structure. The engineered site for surface attachment of heme at Cys80 in an N80C mutant of cytochrome <i>b</i><sub>562</sub> provides the primary basis for the formation of the periodic assembly structure, which is characterized herein by circular dichroism (CD) spectroscopy and high-speed atomic force microscopy (AFM). This assembly represents the first example of the observation of a split-type Cotton effect by heme–heme exciton coupling in an artificial hemoprotein assembly system. Molecular dynamics simulations validated by simulated CD spectra, AFM images, and mutation experiments reveal that the assembly has a periodic helical structure with 3 nm pitches, suggesting the formation of the assembled structure is driven not only by the heme–heme pocket interaction but also by additional secondary hydrogen bonding and/or electrostatic interactions at the protein interfaces of the assembly

    Real-Time Dynamic Adsorption Processes of Cytochrome <i>c</i> on an Electrode Observed through Electrochemical High-Speed Atomic Force Microscopy

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    <div><p>An understanding of dynamic processes of proteins on the electrode surface could enhance the efficiency of bioelectronics development and therefore it is crucial to gain information regarding both physical adsorption of proteins onto the electrode and its electrochemical property in real-time. We combined high-speed atomic force microscopy (HS-AFM) with electrochemical device for simultaneous observation of the surface topography and electron transfer of redox proteins on an electrode. Direct electron transfer of cytochrome <i>c</i> (cyt <i>c</i>) adsorbed on a self-assembled monolayers (SAMs) formed electrode is very attractive subject in bioelectrochemistry. This paper reports a real-time visualization of cyt <i>c</i> adsorption processes on an 11-mercaptoundecanoic acid-modified Au electrode together with simultaneous electrochemical measurements. Adsorbing cyt <i>c</i> molecules were observed on a subsecond time resolution simultaneously with increasing redox currents from cyt <i>c</i> using EC-HS-AFM. The root mean square roughness (<i>R</i><sub>RMS</sub>) from the AFM images and the number of the electrochemically active cyt <i>c</i> molecules adsorbed onto the electrode (<i>Γ</i>) simultaneously increased in positive cooperativity. Cyt <i>c</i> molecules were fully adsorbed on the electrode in the AFM images when the peak currents were steady. This use of electrochemical HS-AFM significantly facilitates understanding of dynamic behavior of biomolecules on the electrode interface and contributes to the further development of bioelectronics.</p></div

    Time-course analysis of <i>R</i><sub>RMS</sub> and <i>Γ</i> values.

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    <p>(A) Time evolution of <i>R</i><sub>RMS</sub> values from the HS-AFM images (open circle) and the level of electrochemically active cyt <i>c</i> (<i>Γ</i>) from the cyclic voltammograms (open square). (B) Schematic of the adsorbing cyt <i>c</i> molecules on the MUA-modified electrode at each time point.</p

    Real-time cyt <i>c</i> desorption processes from the MUA-modified gold electrode.

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    <p>(A) Continuous AFM images of desorbing cyt <i>c</i> molecules. Frame rate, 2 frames/s; image area, 150 × 150 nm<sup>2</sup>. (B) Time evolution of <i>R</i><sub>RMS</sub> values at the higher ionic strengths. (C) Schematic of desorbing cyt <i>c</i> molecules from the MUA-modified electrode. </p

    AFM images show (A) the MUA-modified gold surface and (B) cyt <i>c</i> adsorbed on the MUA SAM at 450 sec.

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    <p>Continuous AFM images of adsorbing cyt <i>c</i> molecules with real-time labels. Frame rate, 2 frames/s; image area, 150 × 150 nm<sup>2</sup>. The cross sections of the images in (A) and (B), along the short white line, are shown in the lower right. </p

    CVs of cyt <i>c</i> adsorbed on the electrode.

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    <p>(A) CVs of cyt <i>c</i> molecules adsorbed on the MUA electrode in a 10 mM phosphate buffer solution (pH 7.0) from 333 to 522 s (from −0.35 V to 0.1 V, each segment is 4.5 s). (B) Background-subtracted CVs from the voltammogram from 313 to 324 s and 333 to 522 s (from inside to outside, each segment is 4.5 s). The voltammograms were collected at a scan rate of 100 mVs<sup>−1</sup>. Ag wire was used as a reference electrode. </p
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