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Ohkubo T, Nakayasu H, Takeuchi Y, Takeyasu N, Kuroda Y. Acidic layer-enhanced nanoconfinement of anions in cylindrical pore of single-walled carbon nanotube. J Colloid Interface Sci 2023; 629:238-244. [PMID: 36155918 DOI: 10.1016/j.jcis.2022.09.070] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/07/2022] [Accepted: 09/12/2022] [Indexed: 11/19/2022]
Abstract
The adsorption of the nitrate ion by the cylindrical pore of single-walled carbon nanotubes (SWCNT) was found to be aided by an acidic adsorbed layer. Adsorbed water in the vicinity of the pore wall can supply protons through ionization, forming the acidic layer, according to Raman spectra and results of solution pH fluctuations caused by ion species adsorption. Such an acidic adsorbed layer leads to surplus adsorption of anionic species where the adsorbed amount of nitrate ions is much larger than that of cations. Also, we could observe the Raman bands being assignable to the symmetrical stretching mode at an extremely high-frequency region for nano-restricted nitrate ions compared to any other bulk phases. The abnormal band shift of adsorbed nitrate ions indicates that the nitrate ions are confined in the pore under the effects of nanoconfinement by the pore and the strong interaction with the acidic layer in the pore. Our results warn that we have to construct the adsorption model of aqueous electrolytes confined in carbon pores by deliberating the acid layer formed by the adsorbed water.
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Affiliation(s)
- Takahiro Ohkubo
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan.
| | - Hiroki Nakayasu
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yuki Takeuchi
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Nobuyuki Takeyasu
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yasushige Kuroda
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
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Ohkubo T, Hirano Y, Nakayasu H, Kuroda Y. Polyiodide Production Triggered by Acidic Phase of Aqueous Solution Confined in Carbon Nanospace. CHEM LETT 2022. [DOI: 10.1246/cl.220303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Takahiro Ohkubo
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yuri Hirano
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Nakayasu
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yasushige Kuroda
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
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Qian J, Gao X, Pan B. Nanoconfinement-Mediated Water Treatment: From Fundamental to Application. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8509-8526. [PMID: 32511915 DOI: 10.1021/acs.est.0c01065] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Safe and clean water is of pivotal importance to all living species and the ecosystem on earth. However, the accelerating economy and industrialization of mankind generate water pollutants with much larger quantity and higher complexity than ever before, challenging the efficacy of traditional water treatment technologies. The flourishing researches on nanomaterials and nanotechnologies in the past decade have generated new understandings on many fundamental processes and brought revolutionary upgrades to various traditional technologies in almost all areas, including water treatment. An indispensable step toward the real application of nanomaterials in water treatment is to confine them in large processable substrate to address various inherent issues, such as spontaneous aggregation, difficult operation and potential environmental risks. Strikingly, when the size of the spatial restriction provided by the substrate is on the order of only one or several nanometers, referred to as nanoconfinement, the phase behavior of matter and the energy diagram of a chemical reaction could be utterly changed. Nevertheless, the relationship between such changes under nanoconfinement and their implications for water treatment is rarely elucidated systematically. In this Critical Review, we will briefly summarize the current state-of-the-art of the nanomaterials, as well as the nanoconfined analogues (i.e., nanocomposites) developed for water treatment. Afterward, we will put emphasis on the effects of nanoconfinement from three aspects, that is, on the structure and behavior of water molecules, on the formation (e.g., crystallization) of confined nanomaterials, and on the nanoenabled chemical reactions. For each aspect, we will build the correlation between the nanoconfinement effects and the current studies for water treatment. More importantly, we will make proposals for future studies based on the missing links between some of the nanoconfinement effects and the water treatment technologies. Through this Critical Review, we aim to raise the research attention on using nanoconfinement as a fundamental guide or even tool to advance water treatment technologies.
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Affiliation(s)
- Jieshu Qian
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 China
| | - Xiang Gao
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
| | - Bingcai Pan
- Research Center for Environmental Nanotechnology (ReCENT), School of Environment, Nanjing University, Nanjing 210023 China
- State Key Laboratory of Pollution Control and Resources Reuse, Nanjing University, Nanjing 210023 China
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The first evaluation of the dynamic hydration number of hydrated ions confined in mesoporous silica MCM-41. ADSORPTION 2019. [DOI: 10.1007/s10450-019-00061-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Tanigaki N, Murata K, Hayashi T, Kaneko K. Mild oxidation-production of subnanometer-sized nanowindows of single wall carbon nanohorn. J Colloid Interface Sci 2018; 529:332-336. [PMID: 29933155 DOI: 10.1016/j.jcis.2018.06.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/05/2018] [Accepted: 06/08/2018] [Indexed: 11/28/2022]
Abstract
The size control of nanowindows on the graphene walls is indispensable to develop innovative adsorption and separation technologies. As single wall carbon nanohorn (SWCNH) consists of graphene wall, the permeation of ions through the nanowindows can be evaluated with adsorption measurement. We regulated the nanowindow size by use of mild oxidation at 473-523 K for 20-70 h. The explicit low pressure adsorption hysteresis was observed in the N2 adsorption isotherms of thus-oxidized SWCNHs, suggesting the window size of 0.3-0.4 nm. Moreover, the aqueous phase adsorption measurement for Li+, Na+, K+, Rb+, and Cs+ indicates that the nanowindow size is smaller than about 0.37 nm, being close to the estimated size from N2 adsorption.
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Affiliation(s)
- Naoto Tanigaki
- Department of Mathematics and System Development, Interdisciplinary Graduate School of Science and Technology, Shinshu University, Nagano 380-8553, Japan
| | - Katsuyuki Murata
- Center for Energy and Environmental Science, Shinshu University, Nagano 380-8553, Japan
| | - Takuya Hayashi
- Department of Water Environment and Civil Engineering, Faculty of Engineering, Shinshu University, Nagano 380-8553, Japan
| | - Katsumi Kaneko
- Center for Energy and Environmental Science, Shinshu University, Nagano 380-8553, Japan.
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Ohkubo T, Kusudo T, Kuroda Y. Asymmetric hydration structure around calcium ion restricted in micropores fabricated in activated carbons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:464003. [PMID: 27624154 DOI: 10.1088/0953-8984/28/46/464003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The adsorbed phase and hydration structure of an aqueous solution of Ca(NO3)2 restricted in micropores fabricated in activated carbons (ACs) having different average pore widths (0.63 and 1.1 nm) were investigated with the analysis of adsorption isotherms and x-ray absorption fine structure (XAFS) spectra on Ca K-edge. The adsorbed density of Ca(2+) per unit micropore volume in the narrower pore was higher than in the wider pore, while the adsorbed amount per unit mass of carbon with the narrower pore was half of the amount of ACs with the larger pore. On the other hand, variations in the bands assigned to double-electron (KM I) and 1s → 3d excitations in XAFS spectra demonstrate the formation of a distorted hydration cluster around Ca(2+) in the micropore, although the structural parameters of hydrated Ca(2+) in the micropores were almost consistent with the bulk aqueous solution, as revealed by the analysis of extended XAFS (EXAFS) spectra. In contrast to the hydration structure of monovalent ions such as Rb(+), which generally presents a dehydrated structure in smaller than 1 nm micropores in ACs, the present study clearly explains that the non-spherically-symmetric structure of hydrated Ca(2+) restricted in carbon micropores whose sizes are around 1 nm is experimentally revealed where any dehydration phenomena from the first hydration shell around Ca(2+) could not be observed.
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Affiliation(s)
- Takahiro Ohkubo
- Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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Nanospace-enhanced photoreduction for the synthesis of copper(I) oxide nanoparticles under visible-light irradiation. J Colloid Interface Sci 2014; 421:165-9. [DOI: 10.1016/j.jcis.2014.01.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/10/2014] [Accepted: 01/25/2014] [Indexed: 11/23/2022]
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Nishi M, Ohkubo T, Tsurusaki K, Itadani A, Ahmmad B, Urita K, Moriguchi I, Kittaka S, Kuroda Y. Highly compressed nanosolution restricted in cylindrical carbon nanospaces. NANOSCALE 2013; 5:2080-2088. [PMID: 23376949 DOI: 10.1039/c2nr33681b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We shed light on the specific hydration structure around a zinc ion of nanosolution restricted in a cylindrical micropore of single-wall carbon nanotube (SWNT) by comparison with the structure restricted in a cylindrical mesopore of multi-wall carbon nanotube (MWNT) and that of bulk aqueous solution. The average micropore width of open-pore SWNT was 0.87 nm which is equivalent to the size of a hydrated zinc ion having 6-hydrated water molecules. We could impregnate the zinc ions into the micropore of SWNT with negligible amounts of ion-exchanged species on surface functional groups by the appropriate oxidation followed by heat treatment under an inert condition. The results of X-ray absorption fine structure (XAFS) spectra confirmed that the proportion of dissolved species in nanospaces against the total adsorbed amounts of zinc ions on the open-pore SWNT and MWNT were 44 and 61%, respectively, indicating the formation of a dehydrated structure in narrower nanospaces. The structure parameters obtained by the analysis of XAFS spectra also indicate that the dehydrated and highly compressed hydration structure can be stably formed inside the cylindrical micropore of SWNT where the structure is different from that inside the slit-shaped micropore whose pore width is less than 1 nm. Such a unique structure needs not only a narrow micropore geometry which is equivalent to the size of a hydrated ion but also the cylindrical nature of the pore.
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Affiliation(s)
- Masayasu Nishi
- Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan
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Phillips KA, Palmer JC, Gubbins KE. Analysis of the solvation structure of rubidium bromide under nanoconfinement. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2012.713484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Huang XF, Hu JL, Pan LQ, Li CX, Sun G, Lu KQ, Cao ZX, Wang Q. A weakened structure-breaking effect of Na+ and Cl− on water inside partially filled mesoporous silica. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.03.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tanaka A, Iiyama T, Ohba T, Ozeki S, Urita K, Fujimori T, Kanoh H, Kaneko K. Effect of a Quaternary Ammonium Salt on Propylene Carbonate Structure in Slit-Shape Carbon Nanopores. J Am Chem Soc 2010; 132:2112-3. [DOI: 10.1021/ja9087874] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Akimi Tanaka
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Taku Iiyama
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Tomonori Ohba
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Sumio Ozeki
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Koki Urita
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Toshihiko Fujimori
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Hirofumi Kanoh
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Katsumi Kaneko
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan, and Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan
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Okada T, Harada M, Ohki T. Hydration of ions in confined spaces and ion recognition selectivity. ANAL SCI 2009; 25:167-75. [PMID: 19212049 DOI: 10.2116/analsci.25.167] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The hydration of ions in confined spaces, such as the interior of ion-exchange resins, micelles, and surface monolayers, is discussed on the basis of results obtained with X-ray absorption fine structure studies, electrophoresis, and ion-transfer voltammetry. The general trends are that anions are partly dehydrated therein, whereas cations are likely to keep their first hydration shells. For bromide ions, the hydration numbers under various circumstances have been determined. The extents of dehydration depend not only on the structure of the cationic sites electrostatically attracting bromide ions but also on whether the cationic sites are exposed to a solution or are effectively shielded from it. These findings will be useful for designing the systems for ionic recognition and separation.
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Affiliation(s)
- Tetsuo Okada
- Department of Chemistry, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
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Iiyama T. ELECTROCHEMISTRY 2008; 76:772-777. [DOI: 10.5796/electrochemistry.76.772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Tanimura A, Kovalenko A, Hirata F. Structure of electrolyte solutions sorbed in carbon nanospaces, studied by the replica RISM theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:1507-17. [PMID: 17241081 DOI: 10.1021/la061617i] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The replica RISM theory is used to investigate the structure of electrolyte solutions confined in carbonized polyvinylidene chloride (PVDC) nanoporous material, compared to bulk electrolyte solution. Comparisons are made between the models of electrolyte solution sorbed in the carbonized PVDC material and a single carbon nanosphere in bulk electrolyte solution. Particular attention is paid to the chemical potential balance between the species of the sorbed electrolyte solution and the bulk solution in contact with the nanoporous material. As a result of the strong hydrophobicity of the carbonized PVDC material in the absence of activating chemical groups, the densities of water and ions sorbed in the material are remarkably low compared to those in the ambient bulk solution. The interaction between water molecules and cations becomes strong in nanospaces. It turns out that, in carbon nanopores, a cation adsorbed at the carbon surface is fully surrounded by the hydration shell of water molecules which separates the cation and the surface. Distinctively, an anion is adsorbed in direct contact with the carbon surface, which squeezes a part of its hydration shell out. The tendency increases toward smaller cations, which are characterized as "positive hydration" ions. In the bulk, cations are not hydrated so strongly and behave similarly to anions. The results suggest that the specific capacitance of an electric double-layer supercapacitor with nanoporous electrodes is intimately related to the solvation structure of electrolyte solution sorbed in nanopores, which is affected by the microscopic structure of the nanoporous electrode.
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Affiliation(s)
- A Tanimura
- Institute for Molecular Science, Okazaki 444-8585, Japan
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Ohki T, Harada M, Okada T. Solvation of Ions in Hydrophilic Layer of Polyoxyethylated Nonionic Micelle. Cooperative Approach by Electrophoresis and Ion-Transfer Voltammetry. J Phys Chem B 2006; 110:15486-92. [PMID: 16884271 DOI: 10.1021/jp062493l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrophoretic measurements of micellar mobility have revealed that polyoxyethylated nonionic surfactant micelles have negative zeta potential in various electrolytes, indicating that the partition of anions into the micelle dominates the entire electrolyte partition and the induced surface potential of the micelle. Although an excess of a negative charge is thus revealed in the micelle, it is uncertain whether anions are preferably solvated in the micelles or cations are expelled from the micelles. To determine the solvation energies of single ions in the hydrophilic layer of the micelle, we have performed ion transfer voltammetric measurements at microinterfaces between nitrobenzene and aqueous tetraethyleneglycol solution, which acts as a model for the palisade layer of the micelles. The cooperative utilization of these different methods has allowed us to determine the Gibbs free energy of transfer of a single ion without an extrathermodynamic assumption. On the basis of the resulting values, the partition of ions and the zeta potential induced by the imbalance of anionic and cationic partition have been quantitatively explained.
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Affiliation(s)
- Takumi Ohki
- Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
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Kaneko K, Ohba T, Ohkubo T, Utsumi S, Kanoh H, Yudasaka M, Iijima S. Nanospace Molecular Science and Adsorption. ADSORPTION 2005. [DOI: 10.1007/s10450-005-5893-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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