論文 - 山本 雅博
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Migration Effects Cause Linear Waveform in Cyclic Voltammetry of Metal Anode Electrodeposition/Dissolution without Supporting Electrolyte: Calculations and Experiments on a Model Case 査読あり
Yuko YOKOYAMA, Masahiro YAMAMOTO, Kenji KANO
Electrochemistry 2024年10月
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Yuko YOKOYAMA, Takaaki NAGAI, Akimitsu ISHIHARA, Masahiro YAMAMOTO, Kohei MIYAZAKI, Takeshi ABE, Kenji KANO
Electrochemistry 90 ( 10 ) 103003 - 103003 2022年9月
出版者・発行元：The Electrochemical Society of Japan
Rotating disk voltammograms of electrocatalytic reactions were
often analyzed on a model of the totally irreversible reaction. The
problem with the conventional method is pointed out, and the
validity of an analysis method on a model of the electrocatalytic
reaction is demonstrated for oxygen-reduction reaction (ORR) as an
example. Rotating disk voltammograms of ORRs sometimes show
gradual change in the limiting current region called residual slope.
The phenomenon has been explained on a random distribution
model in which the catalytic sites communicate in long-range
electron transfer with the electronic conductors that locate at
distances (z), and are uniformly distributed with respect to z.
Observed data of an ORR were well reproduced by non-linear least
squares analysis on the random distribution model. The result of the
analysis is briefly discussed. -
Reciprocal Sum Expression for Steady-state Kinetics —Enzyme Reactions and Voltammetry— 査読あり
Yuko YOKOYAMA, Masahiro YAMAMOTO, Kohei MIYAZAKI, Takeshi ABE, Kenji KANO
Electrochemistry 90 ( 10 ) 103002 - 103002 2022年7月
出版者・発行元：The Electrochemical Society of Japan
Steady-state experiments are often conducted to understand
complicated cases in chemistry, since the kinetics does not have a
time valuable and allows simple modeling of the reactions. The
reciprocal of the overall rate of sequential steady-state reactions
is often given in the reciprocal sum formula: sum of the
reciprocals of the rates of the hypothetical rate-limiting processes
at the individual stages. In this paper, the reciprocal sum
relationship is generalized for sequential multi-step steady-state
reactions, and the importance and usefulness of the concept is
shown by applying it to describe several typical steady-state
systems in enzyme reactions and voltammetry using rotating
disk- and ultramicro-electrodes. -
The use of the reference electrode equipped with an ionic liquid salt bridge in electrochemistry of ionic liquids: A convenient way to align the formal potentials of redox reactions in ionic liquids based on the standard hydrogen electrode scale 査読あり
Takashi Kakiuchi, Shota Domae, Taishi Miyadi, Kaito Kibi, Masahiro Yamamoto
ELECTROCHEMISTRY COMMUNICATIONS 126 2021年5月
共著
出版者・発行元：ELSEVIER SCIENCE INC
A hydrophobic ionic liquid composed of a cationic and anionic species having similar magnitudes of hydrophobicity and mobilities can work as a salt bridge separating two electrolyte solutions, that is, the sample solution and the inner solution of the reference electrode. A few examples of superiority of this ionic liquid salt bridge (ILSB) over the traditional salt bridges made of a concentrated aqueous KCl solution have been demonstrated. The present study is a further extension of the use of ILSB to voltammtery of the redox reactions of ferrocene/ferrocenium and cobaltocene/cobaltocenium couples in an ionic liquid, tributyl(2-methoxyethyl) phosphonium bis(pentafluoroethanesulfonyl) amide ([TBMOEP][C2C2N]), which is also used as the ILSB. The obtained mid-point potentials (Ems) are converted straightforwardly to those referred to the standard hydrogen electrode (SHE). A comparison of Em (SHE) values of the two redox couples in [TBMOEP][C2C2N] with the corresponding values in molecular solvents suggests that the environment given by [TBMOEP][C2C2N] to the two redox reactions is macroscopically similar to that of methanol.
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Single ion activity coefficients of chloride ions in aqueous sodium chloride and magnesium chloride estimated potentiometrically based on ionic liquid salt bridge at 298 K 招待あり 査読あり
Takashi Kakiuchi, Masaki Hisazumi, Yasufumi Moriyama, Masahiro Yamamoto
Electrochemistry Communications 124 106953 2021年3月
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Tailored Photoluminescence Properties of Ag(In,Ga)Se2 Quantum Dots for Near-Infrared In Vivo Imaging 査読あり
Tatsuya Kameyama, Hiroki Yamauchi, Takahisa Yamamoto, Toshiki Mizumaki, Hiroshi Yukawa, Masahiro Yamamoto, Shigeru Ikeda, Taro Uematsu, Yoshinobu Baba, Susumu Kuwabata, Tsukasa Torimoto
ACS Applied Nano Materials 3 ( 4 ) 3275 - 3287 2020年2月
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Ryo Murakami, Syuji Kobayashi, Manami Okazaki, Alexander Bismarck, Masahiro Yamamoto
Frontiers in Chemistry 6 2018年9月
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Treatment of oral cancer using magnetized paclitaxel 査読あり 国際共著
Rina Nakakaji, Masanari Umemura, Kenji Mitsudo, Jeong-Hwan Kim, Yujiro Hoshino, Itaru Sato, Takatsugu Masuda, Masahiro Yamamoto, Mitomu Kioi, Toshiyuki Koizumi, Takayuki Fujita, Utako Yokoyama, Masaki Iida, Motohiko Sato, Hiroshi Sato, Shoko Murofushi, Sayaka Shibata, Ichio Aoki, Haruki Eguchi, Iwai Tohnai, Yoshihiro Ishikawa
Oncotarget 9 ( 21 ) 15591 - 15605 2018年3月
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A model of the potential-dependent adsorption of charged redox-active species at the electrode surface 査読あり
Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
Electrochimica Acta 259 542 - 551 2018年1月
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Treatment of oral cancer using magnetized paclitaxel 査読あり 国際共著
R. Nakakaji et al.
Oncotarget 2018年
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Electrochemical Sensing of Neurotoxic Agents Based on Their Electron Transfer Promotion Effect on an Au Electrode 査読あり
Hiroshi Shimada, Shiori Noguchi, Masahiro Yamamoto, Katsuhiko Nishiyama, Yusuke Kitamura, Toshihiro Ihara
ANALYTICAL CHEMISTRY 89 ( 11 ) 5743 - 5748 2017年6月
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出版者・発行元：AMER CHEMICAL SOC
An electrochemical molecular sensor based on a new principle is reported. Nereistoxin (NRT, 4-N,N-dimethylamino-1,2-dithiolane), a naturally occurring neurotoxin (nicotinic acetylcholine receptor agonist), was adsorbed on an Au electrode via Au-S covalent bonding and accelerated the electron transfer between the electrode and the marker, ferricyanide anion. The contrast between the electrochemical responses obtained with the bare and NRT-modified Au electrodes was more pronounced at a low ionic strength of the supporting electrolyte, KCl. In the presence of 1 mM KCl, almost a 0/1 contrast between the signals was obtained through electrostatic interaction between the protonated tertiary amino group of NRT and the anionic ferricyanide ion. No current was observed with an electrode modified with mercaptopropionic acid. An unusually low ionic strength thickened the electric double layer to the degree where current was not observed with the bare electrode. The effect of the electrostatic concentration of the marker ion becomes obvious under such conditions. Commercially available NRT-related pesticides such as Cartap and Bensultap were also detected using the same format after pretreatments by hydrolysis/reduction. The present sensing method was successfully applied to human serum with satisfactory sensitivity.
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Electrostatic roles in electron transfer from [NiFe] hydrogenase to cytochrome c(3) from Desulfovibrio vulgaris Miyazaki F 査読あり
Yu Sugimoto, Yuki Kitazumi, Osamu Shirai, Koji Nishikawa, Yoshiki Higuchi, Masahiro Yamamoto, Kenji Kano
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 1865 ( 5 ) 481 - 487 2017年5月
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出版者・発行元：ELSEVIER SCIENCE BV
Electrostatic interactions between proteins are key factors that govern the association and reaction rate. We spectroscopically determine the second-order reaction rate constant (k) of electron transfer from [NiFe] hydrogenase (H(2)ase) to cytochrome (cyt) c(3) at various ionic strengths (I). The k value decreases with I. To analyze the results, we develop a semi-analytical formula for I dependence of k based on the assumptions that molecules are spherical and the reaction proceeds via a transition state. Fitting of the formula to the experimental data reveals that the interaction occurs in limited regions with opposite charges and with radii much smaller than those estimated from crystal structures. This suggests that local charges in H(2)ase and cyt c(3) play important roles in the reaction. Although the crystallographic data indicate a positive electrostatic potential over almost the entire surface of the proteins, there exists a small region with negative potential on H(2)ase at which the electron transfer from H(2)ase to cyt c(3) may occur. This local negative potential region is identical to the hypothetical interaction sphere predicted by the analysis. Furthermore, I dependence of k is predicted by the Adaptive Poisson-Boltzmann Solver considering all charges of the amino acids in the proteins and the configuration of H(2)ase/cyt c(3) complex. The calculation reproduces the experimental results except at extremely low I. These results indicate that the stabilization derived from the local electrostatic interaction in the H(2)ase/cyt c(3) complex overcomes the destabilization derived from the electrostatic repulsion of the overall positive charge of both proteins. (C) 2017 Elsevier B.V. All rights reserved.
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Electrochemical Sensing of Neurotoxic Agents Based on Their Electron Transfer Promotion Effect on an Au Electrode 査読あり
Hiroshi Shimada, Shiori Noguchi, Masahiro Yamamoto, Katsuhiko Nishiyama, Yusuke Kitamura, Toshihiro Ihara
Anal. Chem. 2017年
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Magnetic metal complex-conducting copolymer core-shell nanoassemblies for single-drug anticancer platform 査読あり
Jeong-Hwan Kim, Haruki Eguchi, Masanari Umemura, Itaru Sato, Shigeki Yamada, Yujiro Hoshino, Takatsugu Masuda, Ichio Aoki, Kazuo Sakurai, Masahiro Yamamoto and Yoshihiro Ishikawa
NPG(Nature Publishing Group) Asia Materials 2017年
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“Electrostatic roles in electron transfer from [NiFe] hydrogenase to cytochrome c3 from Desulfovibrio vulgaris Miyazaki F 査読あり
Yu Sugimoto, Yuki Kitazumi, Osamu Shirai, Koji Nishikawa, Yoshiki Higuchi, Masahiro Yamamoto, Kenji Kano
BBA - Proteins and Proteomics 2017年
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Magnetic metal-complex-conducting copolymer core-shell nanoassemblies for a single-drug anticancer platform 査読あり
Jeong Hwan Kim, Haruki Eguchi, Masanari Umemura, Itaru Sato, Shigeki Yamada, Yujiro Hoshino, Takatsugu Masuda, Ichio Aoki, Kazuo Sakurai, Masahiro Yamamoto, Yoshihiro Ishikawa
NPG Asia Materials 9 ( 3 ) 2017年
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Nanoparticulate agents for magnetic drug delivery systems (DDSs) have extensive applications in targeted drug delivery, contrast imaging and therapeutics. However, no simple synthetic method for magnetic DDS agents has been developed without the need to add magnetic nanoparticles. Here, we describe the one-step fabrication of 'all-in-one' magneto-assemblies using an 'inorganic-metal-salt-free' method, involving spontaneous self-assembly of the water-insoluble prodrug μ-oxo-bis(N,N0-ethylenebis (salicylideniminato)iron) [Fe(salen)] (magnetic core) with polypyrrole (PPy)-b-polycaprolactone (PCL) smart diblock copolymers. In the system, PCL serves as a heat-responsive core scaffold, and PPy serves as an electronic core-size controller and pH-responsive shell. This core-shell nanocomposite has a high-loading capacity (∼90%), and the core size is tunable by incorporating albumin or gum Arabic as bio-coating agents, which also provide colloidal stability, biocompatibility and thermo-stability. Fe(salen), which has intrinsic antitumor activity, also has ubiquitous magnetic properties, which are dramatically enhanced in these molecular assemblies with magnetic coupling. Moreover, these multifunctional nanoassemblies can be delivered magnetically, can serve as magnetic resonance imaging contrast agents, can generate magneto-hyperthermal effects and can enable magnetic field-triggered release of Fe(salen) molecules under acidic conditions.
DOI： 10.1038/am.2017.29
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Potentiometric coulometry using a liquid-film-modified electrode as a reversible surface-confined system 査読あり
Ryutaro Katsube, Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
Journal of Electroanalytical Chemistry 780 114 - 118 2016年11月
共著
© 2016 Elsevier B.V. A reversible surface-confined system for potentiometric coulometry studies was fabricated by the deposition of a liquid film on an electrode surface, and the system was used to detect charge accumulation due to the peroxidase (POD)-catalyzed reduction of H2O2. The components of the liquid film were 1-ethyl-3-methylimidazolium bis(nonafluorobutanesulfonyl)imide as the electrolyte, dibutyl phthalate as the medium, and ferrocene as the redox-active mediator. When the thickness of the liquid film was less than that of the diffusion layer in the minimum potential step of the apparatus, a symmetric voltammogram, according to the Nernst equation, was recorded. The reduction of H2O2 by POD was carried out on the liquid-film-modified electrode and studied by potentiometric coulometry. The addition of H2O2 shifts the electrode potential positively, due to the oxidation of ferrocene. The change in the potential is in agreement with the Nernst equation. Thus, potentiometric coulometry, carried out on the liquid-film-modified electrode, enables the determination of the substrate without the requirement of a calibration curve.
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Current stage and perspectives of pH measurements by use of ionic liquid salt bridge
Takashi Kakiuchi, Masahiro Yamamoto
Bunseki Kagaku 65 ( 4 ) 181 - 191 2016年5月
共著
© 2016 The Japan Society for Analytical Chemistry. The use of a moderately hydrophobic ionic liquid for a salt bridge allows us to accurately measure pH of low ionic strength aqueous solutions, which was not possible by use of a salt bridge based on a concentrated aqueous potassium chloride solution (KClSB). When a sample solution does not contain hydrophobic ions, the ionic liquid salt bridge is promising also in pH measurements of high ionic-strength samples. That ionic liquid salt bridge enables us to measure the single-ion activities of not only hydrogen ions, but also other ionic species gives new perspectives in studying electrolyte solutions, not limited by the traditional framework set by the KClSB.
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Understanding of the Effects of Ionic Strength on the Bimolecular Rate Constant between Structurally Identified Redox Enzymes and Charged Substrates Using Numerical Simulations on the Basis of the Poisson-Boltzmann Equation 査読あり
Yu Sugimoto, Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
JOURNAL OF PHYSICAL CHEMISTRY B 120 ( 12 ) 3122 - 3128 2016年3月
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出版者・発行元：AMER CHEMICAL SOC
To understand electrostatic interactions in biomolecules, the bimolecular rate constants (k) between redox enzymes and charged substrates (in this study, redox mediators in the electrode reaction) were evaluated at various ionic strengths (I) for the mediated bioelectrocatalytic reaction. The k value between bilirubin oxidase (BOD) and positively charged mediators increased with I, while that between BOD and negatively charged mediators decreased with I. The opposite trend was observed for the reaction of glucose oxidase (GOD). In the case of noncharged mediators, the k value was independent of I for both BOD and GOD. These results reflect the electrostatic interactions between the enzymes and the mediators. Furthermore, we estimated k/k degrees (k degrees being the thermodynamic rate constant) by numerical simulation (finite element method) based on the Poisson-Boltzmann (PB) equation. By considering the charges of individual atoms involved in the amino acids around the substrate binding sites in the enzymes, the simulated k/k degrees values well reproduced the experimental data. In conclusion, k/k degrees can be predicted by PB-based simulation as long as the crystal structure of the enzyme and the substrate binding site are known.
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Potentiometric coulometry using a liquid-film-modified electrode as a reversible surfaceconfined system”, J. Electroanal. Chem. 2016, 780, 査読あり
Ryutaro Katsube, Yuki Kitazumi, Osamu Shirai, Masahiro Yamamotob, Kenji Kano
J. Electronal. chem. 2016年
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Strength on the Bimolecular Rate Constant between Structurally Identified Redox Enzymes and Charged Substrates Using Numerical Simulations on the Basis of the Poisson-Boltzmann Equation 査読あり
Masahiro Yamamoto, and Kenji Kano
J. Phys. Chem. 2016年
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Prediction of the Standard Gibbs Energy of Transfer of Organic Ions Across the Interface between Two Immiscible Liquids 査読あり
Toshiyuki Osakai, Yasuhiro Naito, Kazuo Eda, Masahiro Yamamoto
Journal of Physical Chemistry B 119 ( 41 ) 13167 - 13176 2015年10月
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© 2015 American Chemical Society. The non-Bornian solvation model was applied for evaluation of the standard Gibbs energy (δGtr°,W→O) of transfer of organic ions from water (W) to organic solvent (O = nitrobenzene). The solvation energy of an ion in either W or O is basically formulated as the energy required for the formation of a nanosized ion-solvent interface around the ion; however, many organic ions with strongly charged groups (e.g., -SO3-, -CO2-, -NH3+) are preferentially hydrated in O. Here we divided the surface of an ion into hydrated and non-hydrated surfaces and then carried out regression analyses with experimental values of δGtr°,W→O. In the analyses, the local electric field on the surface of an organic ion was evaluated through density functional theory calculation. Good regression results were then obtained with the mean absolute error of 1.9 and 2.4 kJ mol-1 for 34 anions and 63 cations, respectively. These errors correspond to the error of 20 mV in the standard ion-transfer potential (δOWφ°), being only two times larger than the typical experimental error (10 mV) in the voltammetric measurement. This non-Bornian model is promising for theoretical prediction of δGtr°,W→O (or δOWφ°) for organic ions and possibly of the biomembrane permeability for ionic drugs.
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Role of 2-mercaptoethanol in direct electron transfer-type bioelectrocatalysis of fructose dehydrogenase at Au electrodes 査読あり
Yu Sugimoto, Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
ELECTROCHIMICA ACTA 170 242 - 247 2015年7月
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出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD
Effects of the electrode potential on a direct electron transfer (DET)-type bioelectrocatalysis of fructose dehydrogenase (FDH) at Au electrodes were investigated. Adsorbed FDH showed the highest DET activity at an adsorption potential (E-ad) around the point of zero charge (E-pzc). Since FDH stock solution contains 2-mercaptoethanol (ME) for stabilization, ME is partially bound to the Au electrode. However, the DET activity drastically decreased at E-ad >> E-pzc. Au oxide layer is formed at the positive potentials to hinder the interfacial electron transfer. In contrast, only slight decrease in the DET activity was observed at sufficiently negative Ead (<< E-pzc), where ME is reductively desorbed from the Au electrode, but co-exists in the solution. In contrast, when FDH and ME were adsorbed on Au electrodes at an open circuit potential and the FDH- and ME-adsorbed Au electrode was held at such a negative hold potential (Eho) in the buffer without ME, the DET activity drastically decreased. An addition of ME in the test solution prevented the decrease in the DET activity at the negative E-ho. These results indicate that ME close to adsorbed FDH plays a significant role in the stabilization of FDH adsorbed on Au electrodes. (C) 2015 Elsevier Ltd. All rights reserved.
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Yuta Otsuka, Masahiro Yamamoto, Hideji Tanaka, Makoto Otsuka
Bio-Medical Materials and Engineering 25 ( 3 ) 223 - 236 2015年6月
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© 2015 - IOS Press and the authors. All rights reserved. BACKGROUND: Theophylline anhydrate (TA) in tablet formulation is transformed into monohydrate (TH) at high humidity and the phase transformation affected dissolution behavior. OBJECTIVE: Near-infrared spectroscopic (NIR) method is applied to predict the change of pharmaceutical properties of TA tablets during storage at high humidity. METHODS: The tablet formulation containing TA, lactose, crystalline cellulose and magnesium stearate was compressed at 4.8 kN. Pharmaceutical properties of TA tables were measured by NIR, X-ray diffraction analysis, dissolution test and tablet hardness. RESULTS: TA tablet was almost 100% transformed into TH after 24 hours at RH 96%. The pharmaceutical properties of TA tablets, such as tablet hardness, 20 min dissolution amount (D20) and increase of tablet weight (TW), changed with the degree of hydration. Calibration models for TW, tablet hardness and D20 to predict the pharmaceutical properties at high-humidity conditions were developed on the basis of the NIR spectra by partial least squares regression analysis. The relationships between predicted and actual measured values for TW, tablet hardness and D20 had straight lines, respectively. CONCLUSIONS: From the results of NIR-chemometrics, it was confirmed that these predicted models had high accuracy to monitor the tablet properties during storage at high humidity.
DOI： 10.3233/BME-151278
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Coextraction of water into nitrobenzene with organic ions 査読あり
Yasuhiro Naito, Wataru Murakami, Kazuo Eda, Masahiro Yamamoto, Toshiyuki Osakai
Journal of Physical Chemistry B 119 ( 19 ) 6010 - 6017 2015年5月
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© 2015 American Chemical Society. Various organic anions (sulfonates (RSO<inf>3</inf>-), carboxylates (RCO<inf>2</inf>-), and phenolates (RO-)) and ammonium cations (RNH<inf>3</inf>+, R<inf>2</inf>NH<inf>2</inf>+, and R<inf>3</inf>NH+) were distributed in the nitrobenzene (NB)-water system by using Crystal Violet and dipicrylaminate, respectively. The number of water molecules (n) being coextracted into NB with an ion was then determined by the Karl Fischer method. The n values determined and those reported previously showed the variation from 0.51 to 3.4, depending on not only the charged groups but also the noncharged R-groups. In this study, we focused our attention to the strong electric field on the charged group and its facilitation effect for binding water molecules in NB. The local electric field (E<inf>i</inf>) on the surface of an organic ion was evaluated by using Gaussian09 program with a subprogram developed in our recent study. It was found that the n values showed a clear dependence on the average value of E<inf>i</inf> on oxygen or hydrogen atoms, respectively, of an anionic or cationic group.
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A magnetic anti-cancer compound for magnet-guided delivery and magnetic resonance imaging 査読あり
Haruki Eguchi, Masanari Umemura, Reiko Kurotani, Hidenobu Fukumura, Itaru Sato, Jeong Hwan Kim, Yujiro Hoshino, Jin Lee, Naoyuki Amemiya, Motohiko Sato, Kunio Hirata, David J. Singh, Takatsugu Masuda, Masahiro Yamamoto, Tsutomu Urano, Keiichiro Yoshida, Katsumi Tanigaki, Masaki Yamamoto, Mamoru Sato, Seiichi Inoue, Ichio Aoki, Yoshihiro Ishikawa
Scientific Reports 5 2015年3月
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Research on controlled drug delivery for cancer chemotherapy has focused mainly on ways to deliver existing anti-cancer drug compounds to specified targets, e.g., by conjugating them with magnetic particles or encapsulating them in micelles. Here, we show that an iron-salen, i.e., μ-oxo N,N'- bis(salicylidene)ethylenediamine iron (Fe(Salen)), but not other metal salen derivatives, intrinsically exhibits both magnetic character and anti-cancer activity. X-Ray crystallographic analysis and first principles calculations based on the measured structure support this. It promoted apoptosis of various cancer cell lines, likely, via production of reactive oxygen species. In mouse leg tumor and tail melanoma models, Fe(Salen) delivery with magnet caused a robust decrease in tumor size, and the accumulation of Fe(Salen) was visualized by magnetic resonance imaging. Fe(Salen) is an anti-cancer compound with magnetic property, which is suitable for drug delivery and imaging. We believe such magnetic anti-cancer drugs have the potential to greatly advance cancer chemotherapy for new theranostics and drug-delivery strategies.
DOI： 10.1038/srep09194
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Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis 査読あり
Yu Sugimoto, Yuki Kitazumi, Seiya Tsujimura, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
BIOSENSORS & BIOELECTRONICS 63 138 - 144 2015年1月
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出版者・発行元：ELSEVIER ADVANCED TECHNOLOGY
Effects of the electrode poential on the activity of an adsorbed enzyme has been examined by using copper efflux oxidase (CueO) as a model enzyme and by monitoring direct electron transfer (DET)-type bioelectrocatalysis of oxygen reduction. CueO adsorbed on bare Au electrodes at around the point of zero charge (E-pzc) shows the highest DET activity, and the activity decreases as the adsorption potential (E-ad; at which the enzyme adsorbs) is far from E-pzc. We propose a model to explain the phenomena in which the electrostatic interaction between the enzyme and electrodes in the electric double layer affects the orientation and the stability of the adsorbed enzyme. The self-assembled monolayer of butanethiol on Au electrodes decreases the electric field in the outside of the inner Helmholtz plane and drastically diminishes the E-ad dependence of the DET activity of CueO. When CueO is adsorbed on bare Au electrodes under open circuit potential and then is held at hold potentials (E-ho) more positive than E-pzc, the DET activity of the CueO rapidly decreases with the hold time. The strong electric field with positive surface charge density on the metallic electrode (sigma(M)) leads to fatal denaturation of the adsorbed CueO. Such denaturation effect is not so serious at E-ho << E-pzc, but the electric field with negative sigma(M) induces an orientation inconvenient for the DET reaction during the adsorption process. A positively charged neomycin shows a promoter ability to Cue adsorbed at E-ad << E-pzc. The phenomenon is also explained on the proposed model. (C) 2014 Elsevier B.V. All rights reserved.
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Coextraction of Water into Nitrobenzene with Organic Ions 査読あり
Y. Naito et al.
J. Phys. Chem. B 2015年
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Prediction of the Standard Gibbs Energy of Transfer of Organic Ions Across the Interface Between Two Immiscible Liquids 査読あり
Osakai, Toshiyuki et al.
J. Phys. Chem. B 2015年
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Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis 査読あり
Yu Sugimoto et al.
Biosensors and Bioelectronics 2015年
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A magnetic anti-cancer compound for magnet-guided delivery and magnetic resonance imaging 査読あり
Yoshihiro Ishikawa et al.
Scientific Reports 2015年
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Role of 2-mercaptoethanol in direct electron transfer-type bioelectrocatalysis of fructose dehydrogenase at Au electrodes 査読あり
Y. Sugimoto et al.
Electrochimica Acta 2015年
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Predictive evaluation of pharmaceutical properties of direct compression tablets containing theophylline anhydrate during storage at high humidity by near-infrared spectroscopy 査読あり
Y. Otsuka et al.
Bio-Medical Materials and Engineering 2015年
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Characteristics of fast mediated bioelectrocatalytic reaction near microelectrodes 査読あり
Yuki Kitazumi, Tatsuo Noda, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
Physical Chemistry Chemical Physics 16 ( 19 ) 8905 - 8910 2014年5月
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The pseudo-steady-state current due to a mediated enzymatic reaction on a microelectrode is characterized on the basis of theoretical analysis and numerical simulation. The steady-state current is proportional to substrate concentration when the enzymatic reaction is considerably faster than substrate mass transport via nonlinear diffusion. Under such conditions, the reaction plane, where the mass flow of the substrate is converted to that of the mediator, exists near the electrode surface. The steady-state current increases as the diffusion coefficient of the substrate increases. In contrast, the diffusion coefficient and the concentration of the mediator have minor effects on the current. This difference can be explained on the basis of a change in the reaction plane location. When a sufficient amount of enzyme exists in a system, the system can be used as an amperometric biosensor, the response of which is independent of any change in enzyme activity. This journal is © the Partner Organisations 2014.
DOI： 10.1039/c4cp00141a
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Effects of the density difference between water and oil on stabilization of powdered oil-in-water emulsions 査読あり
Ryo Murakami, Hiroshi Moriyama, Tatsuyuki Noguchi, Masahiro Yamamoto, Bernard P. Binks
Langmuir 30 ( 2 ) 496 - 500 2014年1月
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A powdered oil-in-water (o/w) emulsion is a dispersed system in which the continuous phase of a particle-stabilized o/w emulsion is dispersed in air by encapsulating the water globules with hydrophobic particles. During their preparation, oil droplets in water globules are forced to move because of high-shear mixing, leading to creaming of the oil droplets and possible wetting of the hydrophobic particles with the oil droplets, which induces destabilization. To prepare powdered o/w emulsions efficiently, the extent of creaming of the oil droplets has to be suppressed. We describe how to achieve this by mixing two oils of different densities and preparing powdered o/w emulsions from oil mixtures exhibiting a decreasing density difference with water. As the extent of creaming is reduced, enhanced stabilization of the powdered emulsions occurs. © 2013 American Chemical Society.
DOI： 10.1021/la4042056
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Characteristics of fast mediated bioelectrocatalytic reaction near microelectrodes 査読あり
Y. Kitazumi et al.
Phys. Chem. Chem. Phys. 2014年
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A Non-Bornian Analysis of the Gibbs Energy of Ion Hydration 査読あり
W. Murakami et al.
Bull. Chem. Soc. Jpn. 2014年
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Effects of the Density Difference between Water and Oil on Stabilization of Powdered Oil-in-Water Emulsions
R .Murakami et al.
Langmuir 2014年
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A non-Bornian analysis of the Gibbs energy of hydration for organic ions 査読あり
R. Murakami et al.
RSC. Adv. 2014年
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A non-Bornian analysis of the Gibbs energy of hydration for organic ions
Wataru Murakami, Masahiro Yamamoto, Kazuo Eda, Toshiyuki Osakai
RSC Advances 4 ( 53 ) 27634 - 27641 2014年
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Recently, a non-Bornian model was successfully applied to evaluate the Gibbs energy of hydration (ΔG°hyd) for spherical ions (mainly inorganic ions). In this model, the long-range, Born-type electrostatic ion-solvent interaction is not explicitly included in the calculation of ΔG°hyd, since its contribution is small, whereas the short-range interaction, including Coulomb, polarization, and charge-transfer interactions, is considered as the dominant factor that determines the ΔG°hyd of ions. The ΔG°hyd scaled by the surface area of an ion can be given by a quadratic function of the surface field strength (E) of the ion. In this study, the non-Bornian model was further applied to organic ions with charged groups. Using the Gaussian 09 program package, the geometries of ions in vacuum were optimized at the B3LYP/6-311++G(2d,p) level, and the partial atomic charges were computed in the Mulliken, Merz-Kollman (MK), natural population analysis (NPA), Hirshfeld, and ChelpG methods. Introducing a new subprogram, we could estimate local electric fields on the ion surface (van der Waals surface or solvent-accessible surface (SAS)). This enabled us to perform regression analyses based on the non-Bornian model, by using the experimental values of ΔG°hyd for 109 ions. When the NPA-SAS combination was chosen, the best regression result was obtained, giving the mean absolute error of 4.3 kcal mol-1. The non-Bornian model would provide a simple and relatively accurate way of determining ΔG°hyd of ions. This journal is © the Partner Organisations 2014.
DOI： 10.1039/c4ra02422b
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A non-bornian analysis of the gibbs energy of ion hydration
Wataru Murakami, Kazuo Eda, Masahiro Yamamoto, Toshiyuki Osakai
Bulletin of the Chemical Society of Japan 87 ( 3 ) 403 - 411 2014年
共著
A non-Bornian model for understanding the Gibbs energy of ion hydration (δG°hyd) has been proposed, in which only short-range interactions between an ion and solvent molecules adjacent to the ion are considered, while the longrange electrostatic interaction between the ion and the outer bulk solvent is not explicitly included in the model. As the short-range interactions, Coulomb, polarization, and charge-transfer interactions are taken into account. It has thus been shown that the δG°hyd scaled by the solvent-accessible surface (SAS) area of an ion can be given by a quadratic function of the electric field strength E at the SAS. Regression analyses with the derived analytical equation have been performed for the literature values of δG°hyd for spherical ions, including 85 cations (with the charge number, z = 1 to 4) and 53 anions (with z = 1 and 2); good fitting results have been obtained for either the cations or the anions. An additional regression analysis has been performed for 10 representative cations, using the data set employed by Koehl et al. (J. Phys. Chem. B 2009, 113, 5694). Our non-Bornian model has been found to be one of the highest performance models for the prediction of δG°hyd. © 2013 The Chemical Society of Japan.
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A revisit to the non-Bornian theory of the Gibbs energy of ion transfer between two immiscible liquids 査読あり
Wataru Murakami, Kazuo Eda, Masahiro Yamamoto, Toshiyuki Osakai
Journal of Electroanalytical Chemistry 704 38 - 43 2013年9月
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Potentiometric coulometry based on charge accumulation with a peroxidase/osmium polymer-immobilized electrode for sensitive determination of hydrogen peroxide 査読あり
Chi-Hua Nieh, Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
Electrochemistry Communications 33 135 - 137 2013年8月
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Effects of polymorphic transformation on pharmaceutical properties of direct compressed tablets containing theophylline anhydrate bulk powder under high humidity 査読あり
Yuta Otsuka, Masahiro Yamamoto, Hiroyuki Abe, Makoto Otsuka
Colloids and Surfaces B: Biointerfaces 102 931 - 936 2013年2月
共著
The effect of high humidity on the pharmaceutical properties of direct compression tablets containing theophylline anhydrate (TA) was investigated to prepare high quality pharmaceuticals. A mixed powder (230. mg) containing the TA, β-lactose anhydrate, microcrystalline cellulose (MCC) and magnesium stearate was compressed in a die by 8-mm diameter punches with flat surfaces at 4.8. kN. The TA tablets were stored in desiccators at 96% relative humidity and 20°C. Physicochemical properties of the tablets were measured using, powder X-ray diffraction (XRD), X-ray computed tomography (XCT), the tablet hardness test and the dissolution test. The water absorption process could be divided into two stages: 1.0% absorption at for 0-6. h due to absorption of MCC, and 4% absorption at 6-24. h due to hydration of TA. The XRD and XCT results were supported be tablet weight changes in the initial and later stages, respectively. The relationship between tablet hardness and water absorption indicated that the first stage of absorption was more significant. In contrast, the relationship between the dissolved amount at 20. min (D20) and water absorption indicated that the first stage was less effective. The first stage of absorption was due to MCC, but the second was due to hydration of the TA bulk powder. © 2012 Elsevier B.V.
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Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson-Boltzmann equation 査読あり
Y. Kitazumi et al.
Electrochimica Acta 2013年
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Effects of polymorphic transformation on pharmaceutical properties of direct compressed tablets containing theophylline anhydrate bulk powder under high humidity 査読あり
Y. Otsuka et al.
Colloids and Surfaces B: Biointerfaces 2013年
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Diffusion-controlled Detection of Glucose with Microelectrodes in Mediated Bioelectrocatalytic Oxidation 査読あり
T. Noda et al.
Anal. Sci. 2013年
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Potentiometric coulometry based on charge accumulation with a peroxidase/osmium polymer-immobilized electrode for sensitive determination of hydrogen peroxide 査読あり
Chi-Hua Nieh et al.
Electrochem. Comm. 2013年
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A revisit to the non-Bornian theory of the Gibbs energy of ion transfer between two immiscible liquids 査読あり
T. Osakai et al.
J. Electroanal. Chem. 2013年
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Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson-Boltzmann equation
Yuki Kitazumi, Osamu Shirai, Masahiro Yamamoto, Kenji Kano
Electrochimica Acta 112 171 - 175 2013年
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The structure of the diffuse double layer around a nm-sized micropore on porous electrodes has been studied by numerical simulation using the Poisson-Boltzmann equation. The double layer capacitance of the microporous electrode strongly depends on the electrode potential, the electrolyte concentration, and the size of the micropore. The potential and the electrolyte concentration dependence of the capacitance is different from that of the planner electrode based on the Gouy's theory. The overlapping of the diffuse double layer becomes conspicuous in the micropore. The overlapped diffuse double layer provides the mild electric field. The intensified electric field exists at the rim of the orifice of the micropore because of the expansion of the diffuse double layers. The characteristic features of microporous electrodes are caused by the heterogeneity of the electric field around the micropores. © 2013 Elsevier Ltd. All rights reserved.
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Tatsuo NODA, Mizue WANIBUCHI, Yuki KITAZUMI, Seiya TSUJIMURA, Osamu SHIRAI, Masahiro YAMAMOTO, Kenji KANO
Analytical Sciences 29 ( 3 ) 279 - 281 2013年
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Particle Stabilization of Oil-in-Water-in-Air Materials: Powdered Emulsions 査読あり
Ryo Murakami, Hiroshi Moriyama, Masahiro Yamamoto, Bernard P. Binks, Anaïs Rocher
Advanced Materials 24 ( 6 ) 767 - 771 2012年2月
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“Particle stabi- lization of oil-in-water-in-air materials: powdered emulsions” 査読あり
Murakami, R.; Moriyama, H.; Yamamoto, M.; Binks, B. P.; Rocher, A.
Advanced Materials 24 767 - 771 2012年
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電気化学分析（分析化学実技シリーズ，機器分析編・１２） 木原壯林・加納健司著 共立出版 2012年8月15日発行
山本 雅博
Review of Polarography 58 ( 2 ) 103 - 104 2012年
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“Phase-Separation of Ordered D03 Precipitates in A2 + D03 Two-Phase Microstructure of Fe-Si-V Ternary Alloy System ” 査読あり
K. Ota, T. Shinoda, T. Hayashi, T. Kozakai, M. Doi, M. Yamamoto, M. Takagi, A. Matsumuro,
Processing and Fabrication of Advanced Materials XVIII 18 12 - 14 2009年
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Lattice widening in niobium-doped TiO<inf>2</inf> nanotubes: Efficient ion intercalation and swift electrochromic contrast 査読あり
Andrei Ghicov, Masahiro Yamamoto, Patrik Schmuki
Angewandte Chemie - International Edition 47 ( 41 ) 7934 - 7937 2008年9月
共著
Widely accommodating: Novel TiO2/Nb nanotube layers (see picture, right) are grown on a titanium-niobium alloy. Niobium doping of TiO2 enlarges the cell parameters of the anatase lattice (left; Nb green, Ti gray, O red), facilitating the intercalation of H+ and Li+ ions, and even larger Na+ ions (blue) into the lattice. (Figure Presented) © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
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Artificially phase-separated binary self-assembled monolayers composed of 11-amino-1-undecanethiolate and 10-carboxy-1-decanethiolate on Au(1 1 1): A comparative study of two preparing methods 査読あり
Pham Hong Phong, Hyroyuki Tomono, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Electrochimica Acta 53 ( 14 ) 4900 - 4906 2008年5月
共著
出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD
Two methods have been compared for preparing artificially phase-separated two-component SAMs on Au(1 1 1) composed of 11-amino-1-undecanethiolates (AUTe) and 10-carboxyl-1-decanethiolates (CDTe), which would form, thermodynamically, a homogeneously mixed binary SAMs. The first method starts with the formation of a phase-separated binary SAM of AUTe and 2-hydroxy-1-ethanethiolate (HETe) as a template of the artificially phase-separated SAM, followed by the selective desorption of HETe domains and succeeding filling of the vacancy with CDTe. The second method utilizes fluoren-9-ylmethyl N-(11-mercaptoundecyl) carbamate (FMUCe) instead of 11-amino-1-undecanethiol in preparing the template. After the filling with CDTe, the 9-fluorenylmethyloxycarbonyl (Fmoc) group is removed to obtain AUTe domains. Both methods yield artificially phase-separated binary SAMs having AUTe domains of tens nanometer across. The molecularly flat SAM surface with nanometer-scale domains of different acid-base and electrostatic properties are thus created. For preparing binary SAMs with a higher degree of phase separation, the second method is a better choice; a more clear-cut phase separation is achieved. © 2008 Elsevier Ltd. All rights reserved.
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Counterion binding induces attractive interactions between negatively-charged self-assembled monolayer of 3-mercaptopropionic acid on Au(111) in reductive desorption 査読あり
Yukio Kitagawa, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Journal of Solid State Electrochemistry 12 ( 4 ) 461 - 469 2008年4月
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出版者・発行元：SPRINGER
The electrochemical reductive desorption of the self-assembled monolayers of 3-mercaptopropionic acid in an aqueous alkaline solution gives a sharp peak with the full width at half maximum of about 20 mV irrespective of the type of cations in a linear scan voltammogram. This suggests that a strong attractive interaction exists between negatively charged carboxylate groups in the self-assembled monolayer surface due to the counterion binding, which not only simply stabilizes the adsorbed carboxylates but also makes the interaction between the adsorbed thiolates even attractive possibly by forming a two-dimensional ionic crystal. The effect of tetraalkylammonium ions on the shape of the voltammograms was also examined. © 2007 Springer-Verlag.
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``Lattice Widening in Niobium-Doped TiO2 Nanotubes: Efficient Ion Intercalation and Swift Electrochromic Contrast," 査読あり
Ghicov, A.; Yamamoto, M.; Schumki, P.
Angew. Chem. Int. Ed., 47 1 - 5 2008年
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``Artificially phase-separated binary self-assembled monolayers composed of 11-amino-1-undecanethiolate and 10-carboxy-1-decanethiolate on Au(111): A comparative study of two preparing methods," 査読あり
Phong, P. H.; , Tomono ,H.; Nishi, N.; Yamamoto, M. and Kakiuchi, T.
Electrochimica Acta 53 4900 - 4906 2008年
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``Counterion Binding Induces Attractive Interaction between Negatively-charged Self-assembled Monolayer of 3-Mercaptopropionic Acid on Au(111) in Reductive Desorption," 査読あり
Kitagawa, Y.; Hobara, D.; Yamamoto, M.; Kakiuchi, T.
J. Solid State Electrochem. 12 461 - 469 2008年
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Orientation of 1-dodecyl-4-phenylpyridinium ions constituting an ionic liquid at the ionic liquid | water interface studied by second harmonic generation 査読あり
Naoya Nishi, Ryoichi Ishimatsu, Masahiro Yamamoto, Takashi Kakiuchi
Journal of Physical Chemistry C 111 ( 33 ) 12461 - 12466 2007年8月
共著
A hydrophobic room-temperature ionic liquid (RTIL) of 1-dodecyl-4- phenylpyridinium (C12ppy+) ions, the cations with high first hyperpolarizability, was prepared in combination with bis(pentafluoroethylsulfonyl)imide, and the orientation of C 12ppy+ at the RTIL|water and RTIL|air interfaces was analyzed using optical second harmonic generation (SHG). From polarization-dependence measurements and absolute phase measurements, it was found that C12ppy+ ions at the RTIL|air interface are orientated with the main axis of 4-phenylpyridinium moiety (from phenyl to pyridinium direction) tilted at 53° from the surface normal (from RTIL to air direction) and that the dodecyl chain is protruding to the air. At the RTIL|water interface, it was suggested that C12ppy+ is orientated at the tilt angle of 131° from the surface normal (from RTIL to water direction) with the dodecyl chain protruding away from the aqueous phase. © 2007 American Chemical Society.
DOI： 10.1021/jp071538v
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Concentration-dependent switching of the mode of phase separation in ternary self-assembled monolayers of 2-mercaptoethane sulfonic acid, 2-aminoethanethiol and 1-dodecanethiol on Au(1 1 1) 査読あり
Pham Hong Phong, Vladimir V. Sokolov, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Journal of Electroanalytical Chemistry 600 ( 1 ) 35 - 44 2007年2月
共著
Unusually strong apparent surface activity of the pair of 2-mercaptoethane sulfonic acid (MES) and 2-aminoethanethiol (AET) in forming a phase-separated ternary self-assembled monolayer (SAM) composed of MES, AET, and 1-dodecanethiol (DDeT) has been investigated with changing the conditions for preparing the SAM by coadsorption of the thiols from an ethanolic solution. When the total concentration of the thiols, ctotal, is 1 × 10-3 mol dm-3 or higher, the MES-AET pair forms electrostatically stabilized domains from an early stage of the adsorption after the immersion of a gold substrate in the bathing ethanol solution. The total area of the MES-AET domains does not change with time for longer immersion. The adsorption of DDeT is significantly weaker than the MES-AET pair under such conditions, despite the fact that the intrinsic surface activity of DDeT is greater than those of MES and AET. DDeT-rich islands of typically a few nanometer across spread in the SAM and the size and the distribution of the islands are invariant over a week. In contrast, when ctotal is lower than 0.1 × 10-3 mol dm-3, the adsorptivity of DDeT is stronger than that of the MES-AET pair, and MES and AET initially adsorbed are gradually replaced with DDeT at longer immersion time. This switching of the mode of phase separation with the change in ctotal suggests the crucial roles of the electrostatic interaction of MES and AET in the course of the formation of the SAM and of the hydrophilic barrier formed on the domains to prevent the replacement by hydrophobic DDeT molecules. © 2006 Elsevier B.V. All rights reserved.
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“Concentration- dependent Switching of the Mode of Phase Separation in Ternary Self-assembled Monolayers of 2-Mercaptoethane Sulfonic acid, 2-Aminoethanethiol and 1-Dodecanethiol on Au(111),” 査読あり
Phong, P. H.; Sokolov, V. V.; Nishi, N.; Yamamoto, M.; Kakiuchi, T.
J. Electroanal. Chem. 600 35 - 44 2007年
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“Orientation of 1-dodecyl-4-phenylpyridinium ions constituting an ionic liquid at the ionic liquid—water interface studied by second harmonic generation,” 査読あり
Nishi, N.; Yamamoto, M.; Kakiuchi, T.
J. Phys. Chem. C 111 12461 - 12466 2007年
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“光第二高調波発生法による N-アルキルイソキノリ ニウム系イオン液体 | 水界面の構造解析,” 査読あり
西直哉, 山本雅博,垣内隆
分析化学 56 491 - 497 2007年
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Optical second harmonic generation study of the structure of the interface between water and an ionic liquid based on N-alkylisoquinolinium ions 査読あり
Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Bunseki Kagaku 56 ( 6 ) 491 - 497 2007年
共著
出版者・発行元：Japan Society for Analytical Chemistry
The orientation of cations at the interface between water and a room-temperature ionic liquid (RTIL) has been analyzed using optical second harmonic generation. To detect second harmonic light from the RTIL|water interface with high sensitivity, a RTIL, N-dodecylisoquinolinium bis(pentafluoroethylsulfonyl)imide, which is based on N-dodecylisoquinolinium (C12Iq+) having strong hydrophobicity and high hyperpolarizability, has been used. A polarization-dependence measurement of the light intensity of the second harmonic light has suggested that C 12Iq+ is orientated at the RTIL|water interface with the isoquinolinium moiety tilting at 50° with respect to the surface normal, and with the dodecyl moiety protruding to the RTIL phase. © 2007 The Japan Society for Analytical Chemistry.
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Dependence of the redox reaction of cytochrome c on the mixing state of binary self-assembled monolayers composed of 11-aminoundecanethiol and 10-mercaptoundecanoic acid on Au(1 1 1) 査読あり
Pham Hong Phong, Masahiro Yamamoto, Takashi Kakiuchi
Science and Technology of Advanced Materials 7 ( 6 ) 552 - 557 2006年9月
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Electron transfer (ET) of horse heart cytochrome c (cyt c) immobilized on the artificially phase-separated binary self-assembled monolayers (SAMs) composed of 11-amino-1-undecanthiolate (AUTe) and 10-carboxy-1-decanethiolate (MUAe), (p-SAMs) has been investigated. It has been found that cyt c selectively adsorbs on domains of MUAe of the p-SAMs by the electrostatic attraction and the ET of cyt c on p-SAMs is enhanced compared to that of cyt c adsorbed on the homogeneously mixed SAM of AUTe and MUAe and also on the single-component MUA SAM. This suggests a favorable orientation of cyt c on p-SAMs for ET with the electrode. © 2006 NIMS and Elsevier Ltd.
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Fluorine-free and hydrophobic room-temperature ionic liquids, tetraalkylammonium bis(2-ethylhexyl)sulfosuccinates, and their ionic liquid–water two-phase properties 査読あり
Naoya Nishi, Takahiro Kawakami, Fumiko Shigematsu, Masahiro Yamamoto, Takashi Kakiuchi
Green Chemistry 8 ( 4 ) 349 - 355 2006年3月
共著
Fluorine-free and hydrophobic room-temperature ionic liquids (RTILs) composed of the bis(2-ethylhexyl)sulfosuccinate (BEHSS) ion, which is known as the surface-active anion constituting Aerosol OT®, and symmetric tetraalkylammonium ions ((CnH2n+1)4N+; n = 4–8), have been prepared. Physicochemical properties of the water-saturated RTILs such as density, conductivity, viscosity and mutual solubility with water (W) have been measured. The RTIL|W interface is polarizable for the RTILs with n = 5–8 in spite of the high water content, 3.6–8.9 wt% in the water-saturated RTILs. The width of the polarized potential window of the RTIL|W interfaces is quantitatively correlated with the solubility of the RTIL in W. The RTIL–W two-phase systems are not spontaneously emulsified and no reverse micelles are formed in the water-saturated RTILs, although BEHSS- is known to form stable water-in-oil emulsions and reverse micelles in oil–water two-phase systems. © 2006 The Royal Society of Chemistry.
DOI： 10.1039/b511529a
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“Dependence of the redox reaction of cy- tochrome c on the mixing state of binary self-assembled monolayers composed of 11-aminoundecanethiol and 10-mercaptoundecanoic acid on Au(111)” 査読あり
Phong, P.H.; Yamamoto, M.; Kakiuchi, T.
Science and Technology of Advanced Materials 7 552 - 557 2006年
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Novel hydrophobic molten salts based on tetrakis[3,5-bis(trifluoromethyl) phenyl]borate anion for electrochemistry of the molten salt|water interface
Seiichi Imakura, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Proceedings - Electrochemical Society PV 2004-24 523 - 527 2006年
共著
The polarized potential window at the room-temperature molten salt (RTMS)|water (W) interface can be widened using RTMSs composed of a hydrophobic anion, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB). The cations which we used for TFPB-based salts are 1-alkyl-3-methylimidazolium (C nmim+: n = 2,4-8,10,12), N-dodecylpyridinium (C nPy+), trioctylmethylammonium (TOMA+), and N-alkylisoquinolinium (CnIq+, n = 12, 18). Among the RTMSs investigated, [C18Iq][TFPB] is in the liquid state at room temperature. The width of the potential window of [C18Iq][TFPB]|W interface is 800 mV, which allows us to study the transfer of moderately hydrophilic cations and moderately hydrophobic anions across the interface.
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Physicochemical properties of room-temperature molten salts of symmetrical tetraalkyl ammonium diisooctylsulfosuccinates
Takahiro Kawakami, Fumiko Shigematsu, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Proceedings - Electrochemical Society PV 2004-24 519 - 522 2006年
共著
Novel fluorine-free and water-immiscible room-temperature molten salts (RTMSs) composed of symmetrical tetraalkylammonium (Nnnnn· n: length of alkyl chain, n = 4-8) and diisooctylsulfosuccinate (DOSS) have been synthesized. Density, conductivity, and water content of the water-saturated RTMSs at 25°C have been measured. Cyclic voltammograms at the N nnnnDOSS|water interfaces show that the interfaces are polarizable and the width of the potential window at the N6666DOSS |water interface is ca. 300 mV.
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Ideal nonideality in adsorption of 2-aminoethanethiol and 2-mercaptoethane sulfonic acid to form electrostatically stabilized binary self-assembled monolayers on Au(111) 査読あり
Yosuke Ooi, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Langmuir 21 ( 24 ) 11185 - 11189 2005年11月
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In formation of binary self-assembled monolayers (SAMs) composed of 2-aminoethanethiol (AET) and 2-mercaptoethane sulfonic acid (MES) by adsorption from an ethanol solution on Au(111), the adsorption shows nearly ideal nonideality in that the surface ratio of MES to AET in the SAM is unity and does not depend on the mixing ratio of MES to AET in the bathing ethanol solution used for preparing SAMs, χMESsoln, over the wide range of χMESsoln between 0.01 and 0.95. X-ray photoelectron spectroscopy confirms that at least 80% of AET molecules adsorbed are protonated in this range of χMESsoln, indicating that the electrostatic interaction between positively charged AET and negatively charged MES is responsible to the observed nonideality. Correspondingly, there appears only one cathodic peak in a linear-sweep voltammogram of the reductive desorption of the SAM, having a narrow full width at half-maximum of about 20 mV. This suggests the presence of strong lateral attractive interaction between the adsorbed thiolates. © 2005 American Chemical Society.
DOI： 10.1021/la051160x
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Phase separation of ternary self-assembled monolayers into hydrophobic 1-dodecanethiol domains and electrostatically stabilized hydrophilic domains composed of 2-aminoethanethiol and 2-mercaptoethanesulfonic acid on Au(111) 査読あり
Pham Hong Phong, Yosuke Ooi, Daisuke Hobara, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Langmuir 21 ( 23 ) 10581 - 10586 2005年11月
共著
Ternary self-assembled monolayers (SAM) composed of 2-aminoethanethiol (AET), 2-mercaptoethane-sulfonic acid (MES), and 1-dodecanethiol (DDeT) form two types of domains as if it were a two-component SAM: DDeT-rich hydrophobic domains and electrostatically stabilized hydrophilic domains composed of MES and AET on Au(111). MES and AET behave virtually as a single surface-active species. Two distinct reductive desorption peaks in cyclic voltammograms (CV) and binarized images of scanning tunneling microscopy clearly show nanometer scale, yet macroscopically distinguishable, phase separation over a wide range of the mixing ratio of DDeT and MES-AET in the bathing solution. X-ray photoelectron spectroscopy measurements indicate that the ratio of MES to AET in the hydrophilic domains is unity and that both terminal groups are in the charged states, that is, the sulfonate group and the ammonium group. With decreasing the total concentration of the thiols, the mole fraction of DDeT in the bathing solution at which the surface coverage of MES-AET domains is equal to that of DDeT domains dramatically decreases. This suggests that the adsorption kinetics plays a crucial role in the formation of the domains structure. © 2005 American Chemical Society.
DOI： 10.1021/la050444e
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Effect of the charged state of gold substrates on the surface composition of two-component alkanethiol self-assembled monolayers 査読あり
Takeo Arakawa, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Electrochemistry Communications 7 ( 8 ) 848 - 852 2005年8月
共著
The surface composition of the binary self-assembled monolayer (SAM) of 1-tetradecanethiol and 3-mercapto-1-propanol on gold varies with the charged state of the gold substrate because of the difference in the reductive desorption potentials of the two thiol species. This is a direct corollary of the finding by Paik et al. [S. Eu, W.K. Paik, Chem. Lett. 16 (1998) 405-406.] that the adsorption of thiols to a metal surface from the solution phase leads to the accumulation of negative charges on the surface. By controlling the potential of the gold substrate during the formation of a binary SAM, it is possible to change the surface composition. The saturation of the bathing ethanol solution with oxygen and the grounding of the substrate during the formation of the SAM have basically the same effect on the surface composition, as both mitigate the charge-up problem. © 2005 Elsevier B.V. All rights reserved.
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Fluorescence lifetime measurements of coumarin 343 for sub-ps solvation dynamics in W|aerosol-OT|1,2-dichloroethane reverse micelle systems 査読あり
Yasunobu Iwami, Masahiro Yamamoto, Naoya Nishi, Takashi Kakiuchi
Bunseki Kagaku 54 ( 6 ) 485 - 494 2005年6月
共著
The sub-ps solvation dynamics in a water|Aerosol OT (AOT)|1,2- dichloroethane (DCE) reverse micelle system has been investigated by fluorescence lifetime measurements of coumarin 343. From absorption spectroscopic measurements, the fluorescence dye molecules were found to be located at the outer side of the reverse micelle interface. The diffusive part of the sub-ps solvation became slower for smaller micelles with the radius of 2-4 nm. This may be due to the interaction between water and AOT molecules in the smaller micelles. © 2005 The Japan Society for Analytical Chemistry.
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Changes in electronic structure upon lithium insertion into the a-site deficient perovskite type oxides (Li,La)TiO<inf>3</inf> 査読あり
Masanobu Nakayama, Tatsuya Usui, Yoshiharu Uchimoto, Masataka Wakihara, Masahiro Yamamoto
Journal of Physical Chemistry B 109 ( 9 ) 4135 - 4143 2005年3月
共著
Investigation on variation of the electronic structure accompanying the electrochemical lithium insertion into the perovskite type oxide, (Li,La)TiO3, has been carried out by X-ray absorption spectroscopy (XAS). During the electrochemical lithium insertion, titanium ion reduced its oxidation state from Ti4+ to Ti3+, while La3+ does not contribute to the reduction reaction resulting from Ti K-edge and La L3-edge XAS, respectively. Furthermore, O K-edge XAS showed marked spectral changes with electrochemical lithium insertion, indicating the electronic structure around oxide ion affected by lithium insertion reaction. From the XAS measurement, we have concluded the variation observed in O K-edge XAS was related to the strong interaction with inserted Li ion. To confirm this, first-principles band calculations were performed for the perovskite structure before and after electrochemical lithium insertion. The calculated results showed that the electron originated from inserted Li transferred to neighboring oxide ion locally as well as to Ti ion. This may be due to local neutralization effect of Li to reduce the electrostatic interaction in the crystal. © 2005 American Chemical Society.
DOI： 10.1021/jp046062j
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Polarized potential window available at the interface between an aqueous electrolyte solution and tetraalkylammonium imide salts 査読あり
Takashi Kakiuchi, Norihiro Tsujioka, Kenji Sueishi, Naoya Nishi, Masahiro Yamamoto
Electrochemistry 72 ( 12 ) 833 - 835 2004年12月
共著
The polarized potential window (ppw) of 450 mV is available at the interface between water (W) and the room-temperature molten salt (RTMS) that consists of tetraoctylammonium cations and trifluoromethylsulfonylnonafluorobulylsulfonylimide anions. The ppw at the interface between W and RTMS made of several combinations of hydrophobic cations and anions is correlated with the standard ion-transfer potentials of the ions at the 1,2-dichloroethane |W interface. This correlation is useful not only to predict the width of the ppw but also to approximately estimate the point of zero charge at the RTMS|W interface.
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Electrocapillarity at the nonpolarized interface between the aqueous solution and the room-temperature molten salt composed of 1-octyl-3- methylimidazolium bis(pentafluoroethylsulfonyl)imide 査読あり
Takashi Kakiuchi, Fumiko Shigematsu, Takuya Kasahara, Naoya Nishi, Masahiro Yamamoto
Physical Chemistry Chemical Physics 6 ( 18 ) 4445 - 4449 2004年9月
共著
The interfacial tension between the room-temperature molten salt (RTMS, also called ionic liquid) composed of 1-octyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide (C8mimC2C2N) and the aqueous solution containing 1-octyl-3-methylimidazolium chloride or lithium bis(perfluoroethylsulfonyl)imide has been measured as a function of the composition of the aqueous phase. The phase-boundary potential calculated for this non-polarized interface from the solution composition enables us to construct the corresponding electrocapillary curve, which shows a parabolic shape with respect to the variation of the phase-boundary potential over 300 mV. C8 mim+ ions specifically adsorb at the interface. Switching of the potential-determining ion from C8mim+ to C2C2N- causes a jump of more than 160 mV in the potential at the outer Helmholtz plane on the aqueous side of the interface.
DOI： 10.1039/b408333b
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Determination of the potential of zero charge of Au(1 1 1) electrodes modified with thiol self-assembled monolayers using a potential-controlled sessile drop method 査読あり
Yasunobu Iwami, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Journal of Electroanalytical Chemistry 564 ( 1-2 ) 77 - 83 2004年3月
共著
The potential of zero charge (pzc) of the thiol-modified Au(111) electrode has been determined for self-assembled monolayers (SAMs) of octadecanethiolate (ODT), undecanethiolate (UDT), propanethiolate (PT), and 1H,1H,2H,2H-perfluorodecanethiolate (PFDT) by measuring the contact angle of a drop of an aqueous 0.1 moldm-3 NaClO4 solution on the SAM-covered electrode as a function of the electrode potential. The values of the pzc for ODT, UDT, PT, and PFDT SAMs were -0.52, -0.49. -0.3, and 1.04 V (vs. Ag|AgCl|satd. KCl), respectively. The variation of the values is ascribed to the change in the surface potential on the solution side of the electrode|solution interface due to the difference in the dipole moments of alkanethiolates on Au(111), which is supported by the ab initio calculation of these thiolates adsorbed on a four-atom cluster of Au atoms. © 2003 Elsevier B.V. All rights reserved.
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Electrochemical instability in the transfer of cationic surfactant across the 1,2-dichloroethane/water interface 査読あり
Takuya Kasahara, Naoya Nishi, Masahiro Yamamoto, Takashi Kakiuchi
Langmuir 20 ( 3 ) 875 - 881 2004年2月
共著
The electrochemical instability has been shown to appear in the transfer of cationic surfactant ions across the 1,2-dichloroethane/water interface. Cyclic voltammograms possess all fundamental characteristics that are predicted by the theory of electrochemical instability: the presence of the instability window, that is, the potential range where the interface becomes unstable, the location of the instability window around the standard ion transfer potential of surface-active ions, and the dependence of the width of the instability window on the concentration of the surfactant ions. Electrocapillary measurements clearly demonstrate that the interface becomes unstable, while the interfacial tension is positive, being higher than 20 mN m-1. The electrocapillary curve exhibits the discontinuities at both ends of the instability window, indicating the similarity between the electrochemical instability and the phase transitions induced by the temperature, pressure, and chemical potential. The results from voltammetry and interfacial tension measurements for cationic surfactants support the idea that the electrochemical instability, so far reported in the transfer of anionic surfactants across the liquid/liquid interface, is one of intrinsic properties of the two-phase systems where the partition of surface-active ions takes place.
DOI： 10.1021/la035452e
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Morihiro Saito, Hiromasa Ikuta, Yoshiharu Uchimoto, Masataka Wakihara, Shoichi Yokoyama, Takeshi Yabe, Masahiro Yamamoto
The Journal of Physical Chemistry B 107 ( 42 ) 11608 - 11614 2003年10月
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Naoya Nishi, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Langmuir 19 ( 15 ) 6187 - 6192 2003年7月
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Influence of Lewis acidic borate ester groups on lithium ionic conduction in polymer electrolytes 査読あり
Yuki Kato, Kentaro Suwa, Hiromasa Ikuta, Yoshiharu Uchimoto, Masataka Wakihara, Shoichi Yokoyama, Takeshi Yabe, Masahiro Yamamoto
Journal of Materials Chemistry 13 ( 2 ) 280 - 285 2003年2月
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Naoya Nishi, Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
The Journal of Chemical Physics 118 ( 4 ) 1904 - 1911 2003年1月
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Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF2 査読あり
Naoya NISHI, Daisuke HOBARA, Masahiro YAMAMOTO, Takashi KAKIUCHI
Analytical Sciences 19 ( 6 ) 887 - 890 2003年
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Morihiro Saito, Hiromasa Ikuta, Yoshiharu Uchimoto, Masataka Wakihara, Shoichi Yokoyama, Takeshi Yabe, Masahiro Yamamoto
Journal of The Electrochemical Society 150 ( 4 ) A477 - A477 2003年
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Takashi Kakiuchi, Hideyuki Usui, Daisuke Hobara, Masahiro Yamamoto
Langmuir 18 ( 13 ) 5231 - 5238 2002年6月
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Naoya Nishi, Kazuo Izawa, Masahiro Yamamoto, Takashi Kakiuchi
The Journal of Physical Chemistry B 105 ( 34 ) 8162 - 8169 2001年8月
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Reconstruction of Au(111) Following the Reductive Desorption of Self-Assembled Monolayers of 2-Mercaptoethanesulfonic Acid Studied by in Situ Scanning Tunneling Microscopy 査読あり
Daisuke Hobara, Masahiro Yamamoto, Takashi Kakiuchi
Chemistry Letters 30 ( 4 ) 374 - 375 2001年4月
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Molecular Dynamics Simulation of the Transfer of a small and a Large Ion Across the NitrobenzenejWater Interface 査読あり
Yamamoto, M, Kakiuchi
Anal. Sci. 17 i239 - i240 2001年
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Structure of the Pt(111)/liquid interface: a first-principles/RHNC calculation 査読あり
Masahiro Yamamoto, Masahiro Kinoshita, Takashi Kakiuchi
Electrochimica Acta 46 ( 2-3 ) 165 - 174 2000年11月
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Daisuke HOBARA, Kazuhiro UEDA, Shin-ichiro IMABAYASHI, Masahiro YAMAMOTO, Takashi KAKIUCHI
Electrochemistry 67 ( 12 ) 1218 - 1220 1999年12月
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Position-dependent stopping power of low velocity rare gas atoms at a SnTe(0 0 1) surface 査読あり
Kaoru Nakajima, Yukihiro Fukusumi, Kenji Kimura, Michi-Hiko Mannami, M. Yamamoto, S. Naito
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 149 ( 1-2 ) 31 - 37 1999年1月
出版者・発行元：Elsevier
Energy losses of 15-30 keV Ne+, Ar+ and Kr+ ions specularly reflected from a SnTe(001) surface are measured. Because more than 98% of the reflected ions are neutral, the observed energy loss can be considered as the result of atom-surface interactions. From the observed energy losses, position-dependent stopping powers of the SnTe(001) surface for neutral atoms are derived. The obtained stopping powers are compared with the theory of the stopping power for low velocity ions with help of the local density approximation. While the agreement between the experimental and theoretical results is excellent for Ar and Kr atoms, the experimental stopping is about twice larger than the theoretical one for Ne atoms. This discrepancy can be explained in terms of the effect of excited atoms on the stopping power. © 1999 Elsevier Science B.V.
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Position-dependent stopping power of low velocity rare gas atoms at a SnTe(001) surface 査読あり
Nakajima, K.; Fukusumi, Y.; Kimura, K.; Mannami, M.; Yamamoto, M.; Naito, S.
Nucl. Instr. and Meth. B 149 31 - 37 1999年
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Electrical Resistivity of Zirconium Hydrides and Denterides at High Temperatures 査読あり
YAMAMOTO Masahiro
J. Phys. : Condens. Matter 10 ( 21 ) 4645 - 4657 1998年
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Surface Electron Distribution by Fast Ion-Surface Scattering 査読あり
YAMAMOTO Masahiro
Scanning Microscopy 30 217 1998年
単著
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High-temperature Diffusion of Hydrogen and Deuterium in Titanium and Ti3Al 招待あり 査読あり
YAMAMOTO Masahiro
J. Electrochem. Soc. 145 ( 7 ) 2471 - 2475 1998年
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Auger Electron Spectroscopy and Electron Energy Loss Spectroscopy Study of the Adsorption of Nitrogen on a Polycrystalline Zirconium Surface 査読あり
YAMAMOTO Masahiro
J. Vac. Sci. Tech. A. 15 ( 5 ) 2548 - 2552 1997年
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Dependence of the Third-order Coefficients in Landan Free Energies for bcc -) fcc Structural Transition on Hydrogen Concentration in Zirconium Hydrides 査読あり
YAMAMOTO Masahiro
J. Appl. Phys. 82 ( 3 ) 1072 - 1079 1997年
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Structure of the metal-liquid interface : self-consistent combinstion of the first-principles metal calculation and an integral equation method 査読あり
YAMAMOTO Masahiro
Chem. Phys. Lett. 274 ( 5/6 ) 513 - 517 1997年
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Vibrational Properties of a Polycrystalline Titanium Surface Studied by Electron Energy-Loss Fine Structure(EELFS) Analysis 査読あり
YAMAMOTO Masahiro
J. Surf. Anal. 3 ( 2 ) 451 - 457 1997年
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Theoretical Study of Nitrogen Adsorption on Zr(0001) Surface 査読あり
YAMAMOTO Masahiro
Surt. Sci. 387 ( 1-3 ) 300 - 311 1997年
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Surface channeliny of fast ions 査読あり
YAMAMOTO Masahiro
Nucl. Instlu, Methods B 125 ( 1/4 ) 97 - 101 1997年
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Yuh Ashida, Masahiro Yamamoto, Shizuo Naito, Mahito Mabuchi, Tomoyasu Hashino
Journal of Applied Physics 80 ( 6 ) 3254 - 3258 1996年9月
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Yuh Ashida, Masahiro Yamamoto, Shizuo Naito, Mahito Mabuchi, Tomoyasu Hashino
Journal of Applied Physics 80 ( 6 ) 3259 - 3266 1996年9月
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First-principles calculation of the longitudinal phonon in the surface-normal direction of Zirconium(0001) slab : Localization mode at the subsurface 査読あり
YAMAMOTO Masahiro
Phys. Review B 53 ( 20 ) 13772 - 13776 1996年
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First-principles calculations of oxygen adsorption on Zr(0001) 査読あり
YAMAMOTO Masahiro
Phys. Rev. B 54 ( 19 ) 14111 - 14120 1996年
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Naito S, Yamamoto M, Miyoshi T, Mabuchi M, Doi M, Kimura M
Journal of the Chemical Society - Faraday Transactions 92 ( 18 ) 3407 - 3410 1996年
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Diffusion of hydrogen in titanium, Ti<inf>88</inf>Al<inf>12</inf>and Ti<inf>3</inf>Al 査読あり
Miyoshi T, Naito S, Yamamoto M, Doi M, Kimura M
Journal of the Chemical Society - Faraday Transactions 92 ( 3 ) 483 - 486 1996年
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Dissolution of Hydrogen and Deuterium in Titanium Ti2Al6 and Ti3Al 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 91 ( 13 ) 1967 - 1973 1995年
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First-principles calculation of oxygen adsorption on Zr(0001) surface : Possible site occupation between the second and the third layer 査読あり
YAMAMOTO Masahiro
Bull. Amer. Phys. Soc. 40 ( 1 ) 164 1995年
単著
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Electron energy-loss spectra and secondary-electron emission spectra of Zr, ZrN and ZrO2 査読あり
YAMAMOTO Masahiro
J. Phys. : Condensed Matter 7 ( 24 ) 37 - 4772 1995年
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Electron Energy-loss spectha of Sc, Ti, and their oxides 査読あり
YAMAMOTO Masahiro
J. Phys. : Condensed Matter 7 ( 35 ) L463 - L468 1995年
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Electron energy-loss fine structure of a polycrystalline titanium surface 査読あり
YAMAMOTO Masahiro
J. Phys. : Condens. Matter 7 ( 1 ) 37 - 46 1995年
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Naito S, Yamamoto M, Doi M, Kimura M
Journal of the Chemical Society, Faraday Transactions 91 ( 22 ) 4143 - 4147 1995年
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FIRST-PRINCIPLES CALCULATIONS OF THE SURFACE RELAXATION AND ELECTRONIC-STRUCTURE OF ZR(0001)
M YAMAMOTO, CT CHAN, KM HO
PHYSICAL REVIEW B 50 ( 11 ) 7932 - 7939 1994年9月
共著
出版者・発行元：AMERICAN PHYSICAL SOC
The multilayer relaxations of the Zr(0001) surface and the surface electronic structure are studied using first-principles total-energy and force calculations. The distance between the outermost two layers is 4.4-4.7% smaller than the ideal interlayer spacing, while inner layers show oscillatory relaxations. We examined two possible termination sequences for the surface and found that the hcp surface termination is more stable by about 0.06 eV per surface atom as compared to the fee terminated structure. We observed an increase in the local density of states (LDOS) for the surface atoms around the Fermi level relative to the bulk atoms. The increase in the LDOS is found to be closely related to the existence of surface states and resonances around the Fermi level.
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A Theoretical Model for the several Common Stacked Crystals in Arrangement of the stacking sequence of Parallel Atomic Layers in a Simple Crystal Solid 査読あり
Masao Kimura, Masahiro Yamamoto, Mahito Mabuchi, Tomoyasu Hashino
J. Phys. Soc. Japan 63 ( 10 ) 3661 - 3670 1994年
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Diffusion of Hydrogen in Ti3Al 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 90 ( 16 ) 2423 - 2424 1994年
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Structural Transition between HCP and FCC Structures with Considering Configurations of the Position Vectors Defined by Several Common Stacked Model Hamiltonian 査読あり
Masao Kimura, Masahiro Yamamoto, Mahito Mabuchi, Tomoyasu Hashino
J. Phys. Soc. Japan 63 ( 10 ) 3714 - 3728 1994年
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Solubility of Hydrogen and Deuterium in Ti3Al 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 90 ( 9 ) 1355 - 1356 1994年
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High-temperature Diffusion of Hydrogen and Deuterium in Palladium 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 90 ( 6 ) 899 - 903 1994年
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First-principles calculations of the surface relaxation and electronic structure of Zr(0001) 査読あり
YAMAMOTO Masahiro
Phys. Rev. B 50 ( 11 ) 7932 - 7939 1994年
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Effects of Hydrogen and Deuterium Concentration on Measurements of the Solubility and Diffusivity of Hydrogen Isotopes in Yttrium 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 90 ( 13 ) 1979 - 1982 1994年
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Auger Electron, Electron Energy Loss, Secondary Electron Emission and Secondary Ion Mass Spectroscopic Studies on the Oxidation of Hafnium at Room Temperature 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faradsy Trans. 89 ( 19 ) 3611 - 3618 1993年
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Diffusivity and Solubility of Hydrogen and Deuterium in Yttrium 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faradsy Trans. 89 ( 24 ) 4375 - 4379 1993年
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Adsorption Potential of Hydrogen Atom on Zirconium 査読あり
YAMAMOTO Masahiro
J. Phys. Chem. 96 ( 8 ) 3409 - 3412 1992年
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Relativistic Self-Consistent Calculation for Hafnium Atoms and Ions Based on a Relativistic Local Density Functional Theory 査読あり
YAMAMOTO Masahiro
J. Phys. Chem. 96,10784 ( 26 ) 10784 - 10788 1992年
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Mechanism of oxygen absorption by zirconium
Masahiro Yamamoto
1991年3月
単著
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Auger Electron, Electron Energy Loss and Secondary Electron Emission Spectroscopic Studies on the Oxidation of Zirconium at High Temperatures and Room Temperature 査読あり
YAMAMOTO Masahiro
J. Chem. Soc, Faraday Trans 87 ( 10 ) 1591 - 1599 1991年
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Change in the Work Function of Zirconium by Oxidation at High Temperatures and Low Oxygen Pressures 査読あり
YAMAMOTO Masahiro
J. Chem. Soc, Faraday Trans 87 ( 9 ) 1399 - 1403 1991年
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Anomaly in the Rate of Oxygen Absorption by Zirconium dye to the Formation of Oxide at the Surface : Autocatalytic Reaction Model of Oxide Nucleation 査読あり
YAMAMOTO Masahiro
J. Chem. Soc, Faraday Trans 86 ( 22 ) 3797 - 3802 1990年
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Increase in Yields of Secondary Ions by Oxidation of Zirconium at High Temperatures and Low Oxygen Pressures 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans. 86 ( 1 ) 157 - 164 1990年
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Solubility and diffusivity of hydrogen and deuterium in α-hafnium at high temperatures 査読あり
YAMAMOTO Masahiro
J. Phys : condens. Matter 2 ( 8 ) 1963 - 1970 1990年
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Kinetics of Oxygen Absorption by α-Zirconium 査読あり
YAMAMOTO Masahiro
J. Phys. Chem. 93 ( 13 ) 5203 - 5209 1989年
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Pressure Dependence of Oxygen Absorption by Metallic Zirconium with a Clean Surface 査読あり
YAMAMOTO Masahiro
J. Chem. Soc. Faraday Trans 1. 84 ( 12 ) 4235 - 4247 1988年