記述言語：英語   掲載種別：研究論文（学術雑誌）

We show that single-walled carbon nanotube (SWNT) bundles emit visible fluorescence in the presence of noble metal nanoparticles and nanorods in the solid state. Conductivity measurements with metallic nanotubes, isolated from pristine SWNTs, show that they become semiconducting in the presence of the metal nanoparticles. Nanoparticle binding increases the defects in the nanotube structures which is evident in the Raman spectra. The metal-semiconductor transition removes the nonradiative decay channels of the excited states enabling visible fluorescence. Nanotube structures are imaged using this emission with resolution below the classical limits. © 2007 The American Physical Society.

DOI： 10.1103/PhysRevLett.99.167404

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The fabrication of porphyrin molecular nanodevices wired using single-walled carbon nanotubes (SWNT) was investigated. 5,15- bispentylporphyrinato zinc (BPP-Zn) with two pentyl group with two phenyl groups was synthesized to increase the solubility of its SWNT complex in organic solvents. The solution was cast on mica substrate and the surface was observed by tapping-mode atomic force microscopy (AFM). The BPP-Zn complex was observed on the SWNTs as white dots with thicknesses of 2.5-4.5 nm. molecular aggregates of excess BPP-Zn were also seen to be spread across the substrate. The SWNT-wiring method and PCI-AFM can be very effectively combined to measure transport across single or several molecules. This combination allows the simultaneous observation of the topography of the molecules on the electrode during measurement.

DOI： 10.1002/adma.200501249

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The molecular-ruler nanolithography process was used to create photolithographic structures with precise controllable nanometer-scale spacings. This process utilized the selective placement and controlled thickness of self-assembled multilayers to form precise molecular-ruler resists. Some of the advantages of the process include the features of high-resolution and precision, selective deposition, compatibility with different forms of lithographic processing, low production cost, and mild processing conditions. The precise molecular-ruler resists were used to define nanometer-scale spacings between initial and subsequently registered photolithographically patterned structures. Parallel hybrid methodologies used two techniques in combination to fabricate structures that interface nanometer- and micrometer-scale components.

DOI： 10.1002/adma.200600108

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

A random network of Ag/Ag2S nanoparticles (NPs) was used as a physical system in reservoir computing (RC) because the network has nonlinear and dynamical characteristics. Ag/Ag2S NPs were synthesized by the modified Brust-Schiffrin method. Atomic switching among the NPs caused nonlinear dynamical behavior of the random network. The Fourier transform of output signals indicated that the generated harmonics were far higher with a larger amplitude of the input sine wave because the atomic switching occurred only at high bias voltages. Higher accuracy was achieved in the Boolean logic RC task because of the nonlinearity originating from switching. These findings suggest that nonlinearity plays a fundamental role in the design and implementation of RC devices.

DOI： 10.1063/5.0169067

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

An in-material reservoir computing (RC) device with an Ag-Ag2S core-shell nanoparticle (NP) network is proposed. Network-wide nonlinear sine-wave outputs of higher frequencies and varying phases were produced from the different Ag+ ion diffusion rates and filament formation caused by the heterogeneous NP size in the thiol layer. Such emergent dynamics of multiple information regimes enabled the reconstruction of Fourier waves, with a maximum accuracy of 99% achieved only for trained outputs with mixed spatiotemporal complexities. Additionally, the device showed stable retrieval of past information with a two-times-step delay and successfully computed a two-step time-series prediction task with 87% accuracy.

DOI： 10.1021/acsaelm.3c01046

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Conjugated polymers (CPs) have emerged as excellent organic semiconducting materials for flexible electronic applications. CPs exhibit a notably fast carrier transport along their main π-conjugated backbone followed by inter-chain hopping compelling the need to form large and ordered domains in thin films. Therefore, the formation of larger domains, along with their orientation, is critical in controlling the electrical properties of CP-based organic electronic devices. However, controlling the molecular ordering along with the formation of large aggregates is a challenge. In this work, the unidirectional floating film transfer method (UFTM) has been utilized to prepare oriented thin films of CPs, which is a highly facile, cost-effective and material utilization efficient technique. We have demonstrated that extent and direction of molecular orientation in the fabricated thin films can be tuned along with the higher degree of aggregation. The rheological aspects, especially viscosity, play a significant role in determining molecular ordering along with the formation of these large aggregates. Active control of viscosity to achieve a stable interfacial viscous system is paramount to achieving this, resulting in a very high mobility of 12.4 cm2V−1s−1.

DOI： 10.1016/j.cej.2023.143932

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Graphene nanoribbons (GNRs), a quasi-one-dimensional form of graphene, have gained tremendous attention due to their potential for next-generation nanoelectronic devices. The chemical unzipping of carbon nanotubes is one of the attractive fabrication methods to obtain single-layered GNRs (sGNRs) with simple and large-scale production. The authors recently found that unzipping from double-walled carbon nanotubes (DWNTs), rather than single- or multi-walled, results in high-yield production of crystalline sGNRs. However, details of the resultant GNR structure, as well as the reaction mechanism, are not fully understood due to the necessity of nanoscale spectroscopy. In this regard, silver nanowire-based tip-enhanced Raman spectroscopy (TERS) is applied for single GNR analysis and investigated ribbon-to-ribbon heterogeneity in terms of defect density and edge structure generated through the unzipping process. The authors found that sGNRs originated from the inner walls of DWNTs showed lower defect densities than those from the outer walls. Furthermore, TERS spectra of sGNRs exhibit a large variety in graphitic Raman parameters, indicating a large variation in edge structures. This work at the single GNR level reveals, for the first time, ribbon-to-ribbon heterogeneity that can never be observed by diffraction-limited techniques and provides deeper insights into unzipped GNR structure as well as the DWNT unzipping reaction mechanism.

DOI： 10.1002/smll.202301841

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）

Sensing technology is an important aspect of information processing. Current development in artificial intelligence systems (especially those aimed at medical and environmental applications) requires a lot of data on the chemical composition of biological fluids or environmental samples. These complex matrices require advanced sensing devices, and photoelectrochemical ones seem to have potential to overcome at least some of the obstacles. Furthermore, the development of artificial intelligence (AI) technology for autonomous robotics requires technology mimicking human senses, also those operating at the molecular level, such as gustation and olfaction. Again, photoelectrochemical sensing can provide some suitable solutions. In this review, we introduce the idea of integration of photoelectrochemical sensors with some unconventional computing paradigm – reservoir computing. This approach should not only boost the performance of the sensors itself, but also open new pathways through science. Integration of sensing devices with computing systems will also contribute to a better understanding (or at least mimicking) of the human senses and neuromorphic sensory information processing. Although reservoir systems can be considered magic “black boxes” and their operation is at the same time simple and hard to comprehend, this combination is expected to open a new era of effective information harvesting and processing systems.

DOI： 10.1016/j.ccr.2023.215155

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Dielectric biosensor based on nematic liquid crystal platform has been fabricated using sandwich immunoassay technique for the detection of a biomolecule, human cardiac troponin I (cTnI). The optical response of Liquid crystal (LC) biosensor and its corresponding frequency-dependent dielectric properties have been investigated as a function of cTnI concentration. Gold nanoparticles conjugate with detection antibody (AB-GNP) is used for the enhancement of both the optical and dielectric signal of the biosensor. AB-GNP binding with cTnI alter the surface energy of the substrate causing disturbances in LC alignment resulting in a change in transmission. The transmission of the LC cell has been found to be varying from dark to bright texture under polarized microscope as a function of cTnI concentration. A change in low-frequency permittivity with increasing cTnI concentration that forms an increasing order of sandwich immunocomplex with AB-GNP revealed an interfacial surface phenomenon. A positive shift in the onset frequency of permittivity is observed due accumulation of immunocomplex with increasing concentration of cTnI at electrode/LC interface. The dielectric response ε′ of the biosensor is fitted with Hill-Langmuir equation over a concentration range of 0.01 to 10 ng mL−1 cTnI. The dissociation constant ‘Kd’ of 1.02 ± 0.24 ng/mL−1 indicates strong cTnI binding affinity for substrate antibody. A nearby value of 1, calculated for Hill coefficient ‘n’ revealed no co-operativity characteristic of cTnI binding to the primary capture antibody, wherein each binding site of the antibody functions independently at the electrode surface, causing accumulation of charged species revealing LC interfacial surface electrical property.

DOI： 10.1016/j.molliq.2023.121754

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Computation performance of in-materio reservoir device was evaluated by varying intensity of noise injection. Materials for the reservoir device was synthesized using a α-Fe2O3/titanium bismuth oxide composite by using the sol-gel method. The prepared samples were characterized by conducting X-ray diffractmetry, transmission electron microscopy, and energy dispersive X-ray spectroscopy to confirm presence of α-Fe2O3, TiO2, and Bi4Ti3O12 nanoparticles. The I-V and V-t curves show nonlinearity, and phase differences between input and output signals, and the fast Fourier transform of the V-t curve showed high harmonics at the input sine wave with 11 Hz of frequency. In the waveform prediction task, the prediction accuracy was improved only when a small intensity of white noise voltage was superimposed to the input information signal.

DOI： 10.35848/1347-4065/acbd5b

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記述言語：英語   掲載種別：研究論文（学術雑誌）

A physical reservoir that accepts direct light irradiation as input was developed using a Ag2S island network. Short-term memory and nonlinearity required for reservoirs are achieved by the diffusion of Ag+ cations in each Ag2S island and the growth of Ag filaments between Ag2S islands. We found that direct light irradiation to Ag2S islands changes local conductivity in a reservoir, which enhances the performance in short-term memory and nonlinearity of the reservoir. Using the effect, we performed a pattern classification of light that was irradiated to a Ag2S island network reservoir through a rectangular slit, which resulted in the accuracy of over 95%.

DOI： 10.35848/1347-4065/acab0a

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Reservoir computing is expected as low-power AI software or hardware systems because learning is performed only in one layer of the artificial neural network with a middle layer made of a random network with non-linear nodes. Inmaterio reservoir device is a kind of physical reservoir in which the middle layer is made of a random network of materials. Here, we would like to introduce how in-materio reservoir works and can be applied to smart sensors and autonomous robotics.

DOI： 10.23919/SNW57900.2023.10183926

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

For scientists in numerous fields, creating a physical device that can function like the human brain is an aspiration. It is believed that we may achieve brain-like spatiotemporal information processing by fabricating an in materio reservoir computing (RC) device because of a complex random network topology with nonlinear dynamics. One of the significant drawbacks of a two-dimensional physical reservoir system is the difficulty in controlling the network density. This work reports the use of a 3D porous template as a scaffold to fabricate a three-dimensional network of a single-walled carbon nanotube polyoxometalate nanocomposite. Although the three-dimensional system exhibits better nonlinear dynamics and spatiotemporal dynamics, and higher harmonics generation than a two-dimensional system, the results suggest a correlation between a higher number of resistive junctions and reservoir performance. We show that by increasing the spatial dimension of the device, the memory capacity improves, while the scale-free network exponent (γ) remains nearly unchanged. The three-dimensional device also displays improved performance in the well-known RC benchmark task of waveform generation. This study demonstrates the impact of an additional spatial dimension, network distribution and network density on in materio RC device performance and tries to shed some light on the reason behind such behavior.

DOI： 10.1039/d2nr04619a

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.35848/1882-0786/acae6a

記述言語：英語   掲載種別：研究論文（学術雑誌）

Integrating sensory devices with wireless power transfer technology for remote sensing requires the implementation of complex electronic circuitry and communication protocols. To overcome this challenge and remotely monitor mechanical force, we directly integrated piezo-responsive porous multi-walled carbon nanotubes/polydimethylsiloxane nanocomposites with a near-field wireless power transfer system. The wireless system transfers power bidirectionally between the transmitter and the sensing receiver at the resonant frequency of 13.56 MHz. The detection principle is based on the mechanical force-induced impedance changes in the receiver circuit. The modulated impedance signal is detected wirelessly at the transmitter circuit via a full-bridge rectifier and smoothing capacitor. Furthermore, we demonstrate the wireless monitoring of finger bending and applied force using our flexible and disposable sensor without using any energy storage devices. The results suggest a response and recovery time of 400 ± 50 ms, strain sensitivity of 24.73, and pressure sensitivity of 0.98. Our approach adds a new path for disposable haptic-based sensory applications that do not require complex communication protocols in medical, robotics, and other fields.

DOI： 10.1109/JSEN.2023.3248021

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（研究会，シンポジウム資料等）

<p><b>Introduction: </b>In this paper, we present the current status of reservoir computation (RC) device development. In particular, not only are reservoir elements used as AI for image recognition and other applications, but also new "intelligent" sensing methods using them as RC devices are introduced here, such as a soft sponge-like sensor (1) that can detect tomato ripeness (2).</p><p>RC is a computational framework derived from RNN (Figure 1a) that maps input signals to a higher dimensional computational space through the dynamics of a fixed nonlinear system called a reservoir. After an input signal is input to the reservoir, which is treated as a black box, a simple readout mechanism reads the state of the reservoir and learns to map it to the desired output. since RC is developed to mimic brain functions, such as signal feedback to the reservoir, and neuromorphic operations (3-5) (Figure 1b). To be practical as in-material computing devices using nanomaterials and nanoparticles and to realize efficient information processing systems, robust nonlinearity and memory properties are required. To learn this requirement, we aimed to utilize not only highly conductive molecular networks (6) but also various materials such as Ag/Ag2S nanoparticle assemblies and CNT/polyoxometalate (POM) nanoparticles (7), which have nonlinear conduction regions at the nanoscale.</p><p></p><p><b>Method: </b>Random networks of CNTs and other materials were fabricated on a substrate with 16 electrodes extending to the center and forming a gap of several hundred nm. The output of the change in voltage over time was added for each electrode, and the recognition success rate was calculated from the results of one-hot vector representation by linear regression using Python. For the in-sensor calculation, a sensor with a CNT content of 0.3 g and a thickness of 0.5 cm was prepared, and measurements were made 50 times each for 9 object recognitions. The obtained data were used as training and validation data for 25 pieces each, and the success rate of each classification was compared when object grasping was performed.</p><p></p><p><b>Results and discussion: </b>The physical RC device using RNW of SWNT/porphyrin-POM (Por-POM) nanoparticle composite fabricated based on the theoretical model previously reported is presented (Figure 1c). The physical RC platform consisting of the SWNT-Por-POM composite network successfully executes the basic characteristics of reservoirs: nonlinearity, high-order harmonic generation, and phase delay. A supervised object classification task using one-hot vectors with the object grasping tactile signal of a Toyota assisted living robot (HSR) (9) was performed according to the task of the RoboCup World Championship. This is the first reported example of introducing a material physics RC device directly into a robot for object recognition (8,10) and has been introduced in many fields (11). Currently, we are aiming to build an RC system inside a sponge sensor (in-sensor computation) by using the above-mentioned sponge sensor (2), and have recently succeeded in implementing the system in a robot hand (12).</p><p></p><p><b>Conclusion: </b>We have introduced random network material reservoir devices toward in-sensor tactile computing devices, based on the results obtained.</p><p></p><p><b>References: </b>1) A. TermehYousefi, H. Tanaka et al., <b>Mater. Sci. Eng. C</b> 77, 1098 (2017). 2) S. Azhari, H. Tanaka et al., <b>IEEE sensors J.</b> 21, 27810, (2021). 3) S. K. Bose et al., <b>Nat. Nanotechnol.</b> (2015). 4) T. Chen et al., <b>Nature</b> 577, 341 (2020). 5) H. Tanaka et al., <b>Nat. Commun.</b> 9, 2693 (2018). Most read 50 published in <b>Nat. Commun.</b> in 2018. 6) Y. Usami, H. Tanaka et al., <b>Adv. Mater. </b>33, 2102688 (2021). 7) T. Ogawa et al., <b>J. Mater. Chem. C</b> (2020).</p><p>View PDF for the rest of the abstract.</p>

DOI： 10.14886/jvss.2023.0_3ca01

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The need for highly energy-efficient information processing has sparked a new age of material-based computational devices. Among these, random networks (RNWs) of carbon nanotubes (CNTs) complexed with other materials have been extensively investigated owing to their extraordinary characteristics. However, the heterogeneity of CNT research has made it quite challenging to comprehend the necessary features of in-materio computing in a RNW of CNTs. Herein, we systematically tackle the topic by reviewing the progress of CNT applications, from the discovery of individual CNT conduction to their recent uses in neuromorphic and unconventional (reservoir) computing. This review catalogues the extraordinary abilities of random CNT networks and their complexes used to conduct nonlinear in-materio computing tasks as well as classification tasks that may replace current energy-inefficient systems.

DOI： 10.1088/2634-4386/ac676a

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CiNii Research

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記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In recent years, the superior computational power of deep learning based on software has been widely recognized, and the practical applications of artificial intelligence are rapidly expanding. On the other hand, the hardware for replacing to such artificial intelligence (AI) algorithms is facing the physical limits of scaling in silicon CMOS technology, and performance improvement is expected to hit the ceiling. For this reason, there is a growing interest in hardware technologies that physically implement artificial neural networks (ANNs), neuromorphic information processing systems, and the applications, as well as new materials and devices. Here, we report results on materials that can complement CMOS for AI systems such as organic polymers and nanocarbon materials. We will also report further trial to apply the materials to autonomous AI robots.

DOI： 10.23919/AM-FPD54920.2022.9851380

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Carbon nanotubes (CNT)/polydimethylsiloxane (PDMS) have been investigated as potential materials for tomato-harvesting applications. The current-voltage (I-V) and current time (I-t) properties, as well as tomato hardness measurement and support-vector machine learning, were used to determine the performance of the sensor with respect to sensitivity, response time, accuracy, and detection limit of the nanocomposite. The data suggested an accurate (± 5.2%) measurement in a low-weight region of tomato. Narrowing of the I-V hysteresis curve towards a higher weight region was observed as a result of the increase in electron pathways. The fabricated sensor displayed a higher sensitivity (15 mV / mu text{m} ) than the commercial sensor (1 mV / mu text{m} ). In addition, machine learning of the resistance-displacement curve data yielded an average accuracy level of 0.67 when tested using acquired data.

DOI： 10.1109/JSEN.2021.3124914

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The nano-size effects of high-Tc cuprate superconductor La2−xSrxCuO4 with x = 0.20 are investigated using X-ray diffractometry, Transmission electron microscopy, and muon-spin relaxation (µSR). It is investigated whether an increase in the bond distance of Cu and O atoms in the conducting layer compared to those of the bulk state might affect its physical and magnetic properties. The µSR measurements revealed the slowing down of Cu spin fluctuations in La2−xSrxCuO4 nanoparticles, indicating the development of a magnetic correlation at low temperatures. The magnetic correlation strengthens as the particle size reduces. This significantly differs from those observed in the bulk form, which show a superconducting state below Tc. It is indicated that reducing the particle size of La2−xSrxCuO4 down to nanometer size causes the appearance of magnetism. The magnetism enhances with decreasing particle size.

DOI： 10.3390/nano11123450

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

A method for room temperature demonstration of in-materio reservoir computing (RC) with a single-walled carbon nanotube/porphyrin-polyoxometalate network (SWNT/Por-POM) is proposed. Boolean functions of OR, AND, NOR, NAND, XOR, and XNOR, all were reconstructed with an accuracy >90% via supervised training of linear voltage readouts. The RC pre-requisite of echo-state property and recurrent connection allowed for consistent performances over multiple test datasets and time-shifted target sequences. Moreover, a non-zero machine intelligence index confirmed the presence of negative differential resistance dynamics, incorporating in SWNT/Por-POM the mathematical equivalence of additive and subtractive functions, thereby aiding the construction of such complex Boolean functions.

DOI： 10.35848/1882-0786/ac24db

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Pickering emulsion plays an important role in various industrial fields including food, catalysis, and bioscience. Soy protein isolate (SPI) has been proved feasible for stabilizing Pickering emulsion after modification, though such methods were either difficult to proceed or application restrictive. Herein, we report a simple fabrication of oil-in-water Pickering emulsion using a complex of SPI and carbon nanotubes (CNTs)/carboxymethyl cellulose sodium (CMC-Na). The stability of our emulsion could be kept at a wide range of CNTs diameter, oil fraction, and pH, while the emulsion droplet size might be controlled through the tuning of pH and dispersed phase solvent as well. A strong interaction between SPI and CNTs/CMC-Na is a key factor for the homogeneous distribution of CNTs at the aqueous–organic interface, which benefits the Pickering emulsion formation. Our work will offer some useful thoughts for improving the stability of protein-integrated emulsion.

DOI： 10.1080/1539445X.2021.1996393

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Reservoir computing (RC), a low-power computational framework derived from recurrent neural networks, is suitable for temporal/sequential data processing. Here, we report the development of RC devices utilizing Ag-Ag2S core-shell nanoparticles (NPs), synthesized by a simple wet chemical protocol, as the reservoir layer. We examined the NP-based reservoir layer for the required properties of RC hardware, such as echo state property, and then performed the benchmark tasks. Our study on NP-based reservoirs highlighted the importance of the dynamics between the NPs as indicated by the rich high dimensionality due to the echo state property. These dynamics affected the accuracy (up to 99%) of the target waveforms that were generated with a low number of readout channels. Our study demonstrates the great potential of Ag-Ag2S NPs for the development of next-generation RC hardware.

DOI： 10.35848/1347-4065/abe206

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The electrical transport properties of a turbostratic multilayer graphene nanoribbon (GNR) with various number of layers (1–8 layers) were investigated using a field effect transistor with a single GNR channel. In the turbostratic multilayer GNR with 5 layers or less, the carrier mobility and I /I ratio in the FETs were improved by slightly increasing the conductance with increasing the number of layers, meaning that the excellent semiconducting characteristic. The improvement of the carrier transport properties promotes by the turbostratic stacking structure. In the turbostratic multilayer GNR with 6 layers or more, although the I /I ratio degraded, the conductance extremely improved with increasing the number of layers. This indicates that the turbostratic multilayer GNR with thicker number of layers becomes the significantly lower resistivity wire as a metallic characteristic. We revealed that the crossover point of the physical properties between the semiconducting and metallic characteristics is determined by the strength to screen the surrounding environment effects such as charged impurity on the substrate. Our comprehensive investigation provides a design guidance for the various electrical device applications of GNR materials. on off on off

DOI： 10.1038/s41598-021-89709-z

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11470/jsapmeeting.2021.1.0_263

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

Selective sorting of semiconducting single-walled carbon nanotubes (SWNTs) of single chirality is critical for constructing electronic nanodevices with high performance. Nevertheless, trade-off between yield and chirality purity often exists in conventional SWNTs sorting processes. To solve this problem, we present an extremely facile method for enriching SWNTs with both high yield and high chiral selectivity. Simply by using a solvent mixed with toluene and chlorobenzene at certain volume ratio, the sorting yield of (6,5)SWNTs was largely enhanced via polymer extraction, while the chirality purity of sorted SWNTs could be kept high as well. We further proved that the sorting efficiency would not be lowered even after multiple extractions, while the chirality selectivity of the obtained SWNTs was dependent on exact ratio between the two solvents. Solvent polarity-controlled polymer (or solvent molecule)-SWNTs interaction was believed responsible for our results, which was later successfully testified by molecular dynamics simulations. Our proposed strategy will simplify the selecting process of single chiral SWNTs and benefit the optimization of SWNTs-integrated devices in near future.

DOI： 10.1246/bcsj.20200370

Scopus

CiNii Research

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 Wiley-VCH GmbH Wirelessly powered dielectrophoresis (DEP) of metal oxide particles was performed using a spark-gap Tesla coil (TC). The main contribution of this work is the simplification of the conventional DEP setup that requires attaching wires directly to the electrodes. Wireless power from the TC generates a high output frequency and voltage, which corresponds to that used for the DEP. Therefore, a spark-gap TC was built and utilized to conduct the DEP process. Metal oxides (ZnO and Fe2O3) were used as targets for the assembly. The results showed that the wirelessly powered DEP technique via a TC was successful in assembling the metal oxide particles. Positive and negative DEP phenomena were observed. Positive DEP occurred during ZnO assembly, making particles chain grow 0.92 mm toward the sparks within 60 s. Negative DEP was observed during Fe2O3 assembly, where the repulsion of particles formed a void around the sparks with a 1.45 mm radius. The mechanism of this wireless DEP system is discussed.

DOI： 10.1002/elps.202000102

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 The Japan Society of Applied Physics We succeeded in bridging unzipped graphene nanoribbons (GNRs) and separating them from unwanted single-walled carbon nanotubes (SWNTs) using a frequency-dependent dielectrophoresis (DEP) method by varying the frequency and applied voltage used for future assembly. Atomic force micrographs and Raman spectra proved that unzipped GNRs were successfully bridged by the DEP method at frequencies higher than 13 MHz. The theoretical calculation also supported the finding that only GNRs were collected from a mixture of SWNTs/GNRs suspensions.

DOI： 10.35848/1882-0786/abb68d

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.apsusc.2019.144193

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

ベトナム   ホーチミン市  

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society of Applied Physics. The neuromorphic learning switching behavior was investigated in electric devices that were constructed based on the aggregation of thiol-stabilized Ag/Ag2S core-shell nanoparticles (NPs). The NPs were synthesized using the two-phase modified Brust-Schiffrin procedure and exhibited Ag-S and Ag-S-R bonding states at the surfaces of Ag NPs. The memristive behavior of such a device at room temperature under ambient pressure, which can be used to emulate the functions of biological synapses with long and short memories, is achieved. The importance of the Ag2S and the thiol layer at the surface of Ag NPs for the demonstration of learning behavior, such as the potentiation and depression of synapses in the human brain is explained.

DOI： 10.7567/1347-4065/ab5c77

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）

<p>リザバーコンピューティング(RC)は、リザバー層で行われる演算を物理現象に置換することができる情報処理システムである。我々は、自己ドープ型ポリアニリン分子(SPAN)と Au ナノ粒子(AuNP)からなるネットワーク内に非線形 <i>I-V </i>特性が発生することを明らかにしている。本研究では、RCへの適用可能性を探るため、ナノギャップ電極によって多入力多出力電極間での非線形電気特性および記憶特性を検討した。</p>

DOI： 10.14886/jvss.2020.0_268

CiNii Article

CiNii Research

その他リンク： https://ci.nii.ac.jp/naid/130007959456

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 Trans Tech Publications Ltd, Switzerland. We report the results of the resistivity measurement on La2-xSrxCuO4 nanoparticles with x = 0, 0.05, and 0.20 evaluated by the four-point probe method. The high resistivity value shows the predominance of the inter-grain part. The temperature dependence of the conductivity can be analyzed by variable range hopping model showing the charge carriers are formed by thermal activation. There is no superconducting behavior that could be observed in La2-xSrxCuO4 nanoparticles with x = 0.05 and 0.20.

DOI： 10.4028/www.scientific.net/KEM.860.142

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記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

The original single-molecule rectifier proposed by Aviram and Ratner is based on a donor-σ-acceptor structure, in which σ functions as the insulator to disconnect the π electronic systems of the two parts. However, there have been no reports on experimentally demonstrated highly efficient single-molecule rectifiers based on this mechanism. In this paper, we demonstrate single-molecule rectifiers with perpendicularly connected metal porphyrin-imide dyads. Our proposed molecule rectifiers use hydroxyl groups at both ends as weak anchoring groups. Measurements of the single-molecule current-voltage characteristics of these molecules clearly show that the rectification ratio reached a high value of 14 on average. Moreover, the ratio could be tuned by changing the central metal in the porphyrin core. All of these features can be explained by the energy-level shift of the molecular orbital using a model with three electronic parts.

DOI： 10.1039/c9nr07105a

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2019 IEEE. For several decades, 'von Neumann' computers have been downsized while their performances have been improved. However, the downsizing has reached its limit, imposed by the tunneling effect in the transistor, which also prevents energy consumption. To overcome such limitations, neuromorphic devices have been proposed, which exhibit high performances with significantly low power consumption. In this study, we realize a neuromorphic device based on Ag/Ag2S nanoparticles, which have a switching behavior and allow the easy fabrication of a random network for reservoir computing. We start by fabricating particles with a desired particle size distribution. The amount of allylmercaptan (AM), which is a source of sulfur, was varied in the synthesis stage, and the obtained particles sizes were compared. By changing the concentration of AM, the sizes of Ag/Ag2S core-shell nanoparticles were successfully controlled, which allow us to achieve reservoir computing by aggregation of the particles.

DOI： 10.1109/RSM46715.2019.8943543

Scopus

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

DOI： 10.11470/jsapmeeting.2019.1.0_164

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 The Royal Society of Chemistry. In this study, organic solvent-dispersible nanoparticles of an FeII-1,2,4-triazole spin-crossover complex were synthesized. On mixing the suspension of the spin-crossover nanoparticles with a solution of single-walled carbon nanotubes (SWCNTs), the nanoparticles were strongly adsorbed on the hydrophobic SWCNT bundles, resulting in hybrid network structures. Variable temperature DC electrical conductivity measurements of the hybrid network thin films demonstrated that the conductivities of the composite films were switched by the spin transition of the nanoparticles.

DOI： 10.1039/c8dt02923g

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

<p>CNT / PDMS複合材料をトマト収穫用触覚センサとして構成し、I-VおよびI-t特性を調査した。導電パスの増加により、Ｉ-Ｖ曲線は高重量領域に向かって減少した。硬度測定の結果、トマトの低重量領域において正確で安定した測定が可能となり、 市販のセンサよりも高い感度を示した。トマトの成熟度を判別するためにサポートベクターマシンによる機械学習を行った。その結果、0.67の判別精度であった。</p>

DOI： 10.14886/jvss.2019.0_1Ca12

CiNii Article

CiNii Research

その他リンク： https://ci.nii.ac.jp/naid/130007737480

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2019 Trans Tech Publications Ltd, Switzerland. Nano-size effect on structure of crystal of free-standing La2-xSrxCuO4 (LSCO) nanoparticles was observed to reveal size effects of La-based high-Tc superconducting oxides. Lattice parameters were estimated by changing temperature and time of sintering. It is concluded that heat treatment plays a key role in controlling particle size of sample. Lattice distortions will occur when the particle size of sample becomes smaller.

DOI： 10.4028/www.scientific.net/MSF.966.357

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1088/1361-6528/aac36b/meta

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Japan Society of Applied Physics. Free-standing strontium titanate (SrTiO3/STO) nanoparticles (NPs) were synthesized by the sol-gel method. X-ray diffractometry revealed that the required minimum annealing temperature to synthesize pure and highly crystalline STO NPs was 500 °C. Moreover, morphological observation by field emission scanning electron microscopy showed that the STO NPs have a spherical structure and their size depended on annealing condition. Electrical properties were measured using a low-temperature probing system. Here, an electrode was fabricated by electron beam lithography and the synthesized STO NPs were aligned at the electrodes by dielectrophoresis. The conductance of a sample was proportional to temperature. Two conduction mechanisms originating from hopping and tunneling appeared in the Arrhenius plot.

DOI： 10.7567/JJAP.57.06HE07

Scopus

CiNii Article

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11470/jsapmeeting.2018.1.0_2035

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Japan Society of Applied Physics. The advanced progress of electronic-based devices for artificial neural networks and recent trends in neuromorphic engineering are discussed in this review. Recent studies indicate that the memristor and transistor are two types of devices that can be implemented as neuromorphic devices. The electrical switching characteristics and physical mechanism of neuromorphic devices based on metal oxide, metal sulfide, silicon, and carbon materials are broadly covered in this review. Moreover, the switching performance comparison of several materials mentioned above are well highlighted, which would be useful for the further development of memristive devices. Recent progress in synaptic devices and the application of a switching device in the learning process is also discussed in this paper.

DOI： 10.7567/JJAP.57.03EA06

Scopus

CiNii Article

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Japan Society of Applied Physics. The mechanism of graphene nanoribbon synthesis by the sonication-assisted unzipping of carbon nanotubes (CNTs) was investigated utilizing 4-methoxyphenol and 1,4-dimethoxybenzene as moieties of poly[(m-phenylenevinylene)-co-(2,5-dioctoxy-p-phenylenevinylene)]. The obtained results revealed that unzipping was promoted by 4-methoxyphenol owing to the facile abstraction of its phenolic hydrogen by sonication-generated radicals on CNTs, whereas 1,4-dimethoxybenzene did not facilitate unzipping, since its methoxy hydrogens were hardly abstracted. Moreover, unzipping was also facilitated by trans-stilbene, the double bond of which reacts with CNT radicals. Furthermore, we succeeded in using a general radical initiator, namely, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride to promote unzipping, confirming that it is promoted by radical donors/trapping agents.

DOI： 10.7567/JJAP.57.03ED01

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Royal Society of Chemistry. Cyclic conjugated monomers comprising cyclopentadithiophene-vinylene trimers and their polymers on HOPG are observed using STM and AFM. ROMP of the monomers is performed using a Grubbs catalyst. Their STM images exhibit single chains of planar polymers, whereas their AFM images show elongation of the polymer chains on HOPG.

DOI： 10.1039/c8cc02224k

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 The Author(s). A method to fabricate a bioinspired nanobiosensor using electronic-based artificial taste receptors for glucose diagnosis is presented. Fabricated bioinspired glucose nanobiosensor designated based on an artificial taste bud including an amperometric glucose biosensor and taste bud-inspired circuits. In fact, the design of the taste bud-inspired circuits was inspired by the signal-processing mechanism of taste nerves which involves two layers. The first, known as a type II cell, detects the glucose by glucose oxidase and transduces the current signal obtained for the pulse pattern is conducted to the second layer, called type III cell, to induce synchronisation of the neural spiking activity. The oscillation results of fabricated bioinspired glucose nanobiosensor confirmed an increase in the frequency of the output pulse as a function of the glucose concentration. At high glucose concentrations, the bioinspired glucose nanobiosensor showed a pulse train of alternating short and long interpulse intervals. A computational analysis performed to validate the hypothesis, which was successfully reproduced the alternating behaviour of bioinspired glucose our nanobiosensor by increasing the output frequency and alternation of pulse intervals according to the reduction in the resistivity of the biosensor.

DOI： 10.1038/s41598-017-01855-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 IEEE. Single-layer graphene nanoribbon (sGNR) is a naturally good conductor and is a promising material for use as nanowiring in next generation computers. We have investigated a new fabrication method of sGNR by using a sonochemical technique to facilitate longitudinal unzipping of single-walled carbon nanotubes. The optimization of the fabrication process is discussed using a statistical analysis method of "Design of Experiment" to obtain the longest sGNR by unzipping of SWNT. The obtained results will contribute to downscaling of integrated circuits in the near future.

DOI： 10.1109/RSM.2017.8069173

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 Elsevier B.V. In this work, we reported a chemically modified technique via screen printing method to fabricate carbon nanotubes (CNTs)/Polydimethylsiloxane (PDMS) nanocomposite to monitor the piezoresistive behavior of nanocomposite while applying pressure. Raman, UV/vis and HRTEM results were utilized to verify the quality of CNTs, purified through chemical and physical treatments; carboxylic and hydroxylic functional groups were determined via FTIR. The optimum dispersion ratio of the nanocomposite was observed by FESEM images which clearly show the consistent dispersion of CNTs coated by PDMS. Furthermore, I–V characterization of the developed nanocomposite indicates change in resistivity for a few orders of magnitude before and after treatment in addition to resistance variation as a result of different appl ied pressures. These results indicate the importance of CNTs treatment prior to nanocomposite fabrication in order to obtain lower percolation threshold. Obtained results are useful in development of haptic sensor, artificial finger, and brain like devices for robotics applications.

DOI： 10.1016/j.sna.2017.09.026

Scopus

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

DOI： 10.11470/jsapmeeting.2017.2.0_1943

CiNii Research

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11470/jsapmeeting.2017.2.0_2817

CiNii Research

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2017 The Japan Society of Applied Physics. Graphene nanoribbons (GNRs) were successfully synthesized by the longitudinal unzipping of a single-walled carbon nanotube (SWNT). In this process, a short-duration sonication was performed to unzip the SWNT. The obtained results clearly show that the synthesized GNR is semiconducting. Furthermore, it is also confirmed by Raman spectroscopy that the time variation of the samples during the unzipping process has two types of reaction, namely, fast and slow. Furthermore, the obtained results confirm that the narrower SWNT should be unzipped quickly, whereas the wider SWNT should be unzipped slowly.

DOI： 10.7567/JJAP.56.06GG12

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1088/1361-6528/aa6567/meta

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1063/1.4983349

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.msec.2017.04.040

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1088/1361-6528/aa6567

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 Walter de Gruyter GmbH, Berlin/Boston.Nanostructures are a viable candidate for the construction of simple blood sugar monitoring devices. Electrochemical oxidation based on the immobilization of glucose oxidase (GOx) on carbon nanostructures has paved the way for a modern approach to the determination of glucose levels in blood. Carbon nanotubes (CNTs) exhibit excellent electrical properties, resulting in increased interest in glucose biosensors based on CNTs. Its large surface area and optimum aspect ratio increase the total amount of immobilized biomaterials onto its surface. In this contribution, recent advances in the development of reliable methods to improve the electron-transfer mechanism of GOx in CNT-based glucose biosensors are highlighted. Moreover, mass production and growth mechanism of purified CNTs by chemical vapor deposition were discussed by emphasizing its growth-control aspects.

DOI： 10.1515/revce-2015-0051

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.11470/jsapmeeting.2017.1.0_1878

CiNii Research

担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

<br><br>我々は自作超高真空STM装置を用いカーボンナノチューブをアンジップし得たグラフェンナノリボン(GNR)の研究を行っている。GNR溶液をAu基板上に大気中で滴下し真空槽内にて加熱した。この手法では溶媒の不純物吸着による汚染は避けられない。そこで新たに上記装置に真空分子スプレーを自作し取り付けた。溶媒を真空中に拡散する事で、GNRのみを基板上に吸着できる。詳細を報告する。

DOI： 10.14886/sssj2008.37.0_118

CiNii Article

CiNii Research

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

CiNii Article

CiNii Research

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2016 IEEE.This paper introduces a time-domain weighted-sum calculation operation based on a spiking neuron model, and discusses a resistance-capacitance circuit that performs a calculation operation assumed to be realized in CMOS VLSI technology. A nanodevice that executes this calculation is also presented. The calculation circuit is useful for extremely low power operation. This operation uses the rising slopes of post-synaptic potentials triggered by input spike pulses. In the time-domain calculation circuit, the energy dissipation is independent of the resistance, and only depends on the capacitance and voltages. However, the time constant, which is the product of the resistance and capacitance, should be relatively large to guarantee the calculation resolution, and therefore the resistance should be at the giga-ohms levels. The nanodevice consists of a nanodisk array connected with a fin field-effect transistor. Nanodisk arrays can be fabricated using a self-assembly bio-nano-template technique, and they act as resistors with resistance levels of several giga-ohms. A weighted sum can be achieved with an energy dissipation on the order of 1 fJ, with a number of inputs that can be more than 100. This amount of energy is several orders of magnitude lower than that of conventional digital processors.

DOI： 10.1109/NANO.2016.7751490

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1515/revic-2016-0004

記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11470/jsapmeeting.2016.1.0_2286

CiNii Research

担当区分：最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

DOI： 10.11470/jsapmeeting.2016.1.0_3817

CiNii Research

担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1246/cl.151040

Scopus

CiNii Article

記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1166/jnn.2016.11648

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1246/cl.150034

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CiNii Article

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2015 IEEE.In these decades organic functional materials have been utilized in daily electronic products like organic light emitting diodes or liquid crystals in cellar phones or televisions. At the present stage organic materials are used as mass materials and the most characteristic properties of them arise from cooperative effects of each molecule. However, if each single molecule has their own specific properties and cooperate in a rational way with each other, they should emerge more sophisticated properties. In this regard, we have been studying electronic or magnetic properties of single or small number of molecules, synthetic route for molecular integrated circuits by a successive coupling of the molecular parts, by self-assembling on surface, and combination with carbon nano-materials. In order to emerge new properties, each molecule units should show non-linear and non-symmetric responses. We have been studying design, synthesis, and measurements of organic molecules which can exhibit such responses in single molecules.

DOI： 10.1109/ICSJ.2015.7357378

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Carbon nanotube (CNT)-based electrochemical biosensors are used to determine the concentration of analytes by measuring mass, heat, or oxygen. CNTs, as an immobilizing platform of biomaterials, play an important role in enhancing the electron transfer mechanism of a biosensor. The large surface area and optimum aspect ratio (length to thickness) of CNTs maximize the amount of immobilized biomaterials on the surface. In this study, various aspect ratios of CNTs are reported, based on the alteration of growth mechanisms using CVD. The growth-dependent and -independent parameters of the CNT arrays are studied as functions of the synthesis method. Full Paper: Different aspect ratios of CNTs are reported based on the alteration of growth temperature which may be a useful method of increasing the electron-relaying capacity of enzymatic biosensors due to the presence of the insulating, bulky enzyme molecules. Nanotubes are grown perpendicular to the surface of the silicon substrate in different aspect ratios according to the applied growth temperatures.

DOI： 10.1002/cvde.201507184

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1038/srep14399

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015 American Chemical Society.In this present work, crystalline growth conditions of oriented carbon nanotubes based on chemical vapor deposition (CVD) were optimized. The crystallinity and degree of alignment of the grown carbon nanotubes (CNTs) were characterized by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The effects of four variables, namely, deposition time, deposition temperature, annealing process, and concentration of the precursor on the crystallinity of the CNTs, were explored. Furthermore, the correlation of parameters with the growth mechanism was examined using response surface methodology in an attempt to determine the complex interactions between the variables. A total of 30 runs, including predicting and consolidation runs to confirm the results, were required for screening the effect of the parameters on the growth of the CNTs. On the basis of the investigated model, it was found that the crystallinity of the CNTs grown by the CVD method can be controlled via restriction of the effective parameters. (Graph Presented).

DOI： 10.1021/acs.cgd.5b00534

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記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

Double-decker complexes based on single-molecule magnets (SMMs) are a class of highly promising molecules for applications in molecular spintronics, wherein control of both the ligand oxidative states and the 2D supramolecular structure on carbon materials is of great importance. This study focuses on the synthesis and study of 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP)-Tb III double-decker complexes with different electronic structures comprising protonated, anionic, and radical forms. Magnetic susceptibility measurements revealed that only the anionic and radical forms of the OEP-Tb III double-decker complexes exhibited SMM properties. The barrier heights for magnetic moment reversal were estimated to be 207 and 215 cm -1 for the anionic and radical forms, respectively. Scanning tunneling microscopy (STM) investigations revealed that these OEP-Tb III complexes form well-ordered monolayers upon simple dropcasting from dilute dichloromethane solutions. All three complexes form an isomorphic pseudo-hexagonal 2D pattern, regardless of the differences in the electronic structures of their porphyrin-Tb cores. This finding is of interest for SMM technology as ultrathin films of these materials undergoing chemical transformations will not require any detrimental reorganization. Finally, we demonstrate self-assembly of the protonated 5,15-bisdodecylporphyrin (BDP)-TbIII double-decker complex as an example of successful supramolecular design to achieve controlled alignment of SMM-active sites. Switch it up! By synthesizing octaethylporphyrin (OEP)-TbIII double-decker complexes with different electronic structures (protonated, anionic, and radical forms), the on/off switching of the single-molecule magnets (SMMs) could be achieved. Stable 2D structures of each molecule were also observed by scanning tunneling microscopy (STM). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/chem.201402669

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1143/APEX.5.129201

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We have developed fabrication processes of nanogap electrodes with various metals, by combining the molecular lithography technique, in which self-assembled molecular (SAM) layers with an accurately defined thickness are used for resist, and the electron beam lithography. Until now, the molecular lithography technique has been applied to Au and Pt to fabricate the nanogap electrodes, because a thiol-group of the termini molecule that the SAM resist contains is easily stuck to these metals. In this work, we have extended the technique to various metals on which the SAM layers is hard to be formed, with the help of the X-ray photoelectron spectroscopy (XPS) to obtain information on adhesion conditions of the SAM layers on the metals. Finally, we demonstrate fabrication of the Nb nanogap electrodes with the developed technique. An Au nanoparticle was embedded in between the nanogap, which showed the Coulomb blockade effect and the superconducting gap in the current-voltage curves. © 2011 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.50.035204

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Twisted supramolecular assemblies "nanoscrews", were prepared by using simple porphyrin derivatives and acetonitrile solvent. The electrical properties of the assemblies were measured by using microgap electrodes. The nanoscrew had conductivity and showed photo-current. By changing the solvent, the pitch of the screws and their aggregation shapes could be controlled. © 2009 The Royal Society of Chemistry.

DOI： 10.1039/b915832d

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Dendron-protected porphyrin polymers (Mn ∼ 43000 g mol -1; Mw ∼ 111000 g mol-1) were deposited using the Langmuir-Blodgett method on glass surfaces modified with N-phenyl-3-aminopropyltriethoxysilane. These deposited films were soaked in a solution of a fullerene derivative bearing a pyridinyl moiety. Topographical images of the surface obtained by atomic force microscopy showed that the height of the porphyrin polymers was 3.1 ± 0.5 nm as deposited, and clearly increased to 3.9 ± 0.3 nm upon soaking. The increase in height (about 0.8 nm) corresponded to the diameter of the fullerene, indicating that the pyridinyl moieties of the fullerene molecules bound to the zinc atoms of the porphyrin units. Porphyrin polymers having thiol groups at both ends bridging nano-gapped gold electrodes were fabricated on silicon chips. The chips were soaked in the fullerene derivative solution to make devices containing porphyrin polymers whose central zinc atoms were coordinated by the fullerene derivative. The current-voltage (I-V) characteristics of these devices were measured, and higher conductivity was observed during photoirradiation only when the devices contained both the porphyrin polymer and the fullerene derivative; no photo-response was observed when either component was absent. © 2009 The Royal Society of Chemistry.

DOI： 10.1039/b910638c

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Nanocomposites of long conjugated porphyrin polymers with both ends substituted by gold nanoparticles were prepared by mixing a polymer bearing thiol groups at both ends with gold nanoparticles protected by 2-methylundecane-2-thiol. The nanocomposites were observed by atomic force microscopy (AFM), which showed that the gold nanopartieles were attached at the terminal positions of the porphyrin polymers as expected from height analyses. The height at the terminal position was ca. 3-4 nm and that at the center position was ca. 2nm. The nanocomposites could be dispersed homogeneously on solid surfaces such as HOPG or glass substrates using a pulse injection method under high vacuum. Copyright © 2009 The Chemical Society of Japan.

DOI： 10.1246/cl.2009.542

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The synthesis and spectral and structural characterization of a new family of ruthenium(II) complexes containing 3-bromo-, 3,8-dibromo-, 3-(thiophen-2′, 2″ -yl) -, and 3,8-(thio-phen-2′,2″-yl)- l,10-phenanthroline (phen) ligands is described. UV/Vis spectroscopy is used to compare the differences between the conjugated π systems in these ligands and their respective [Ru(bpy)2]2+ (bpy = 2,2′- bipyridine) analogs. Density functional theory (DFT) computations have been carried out to compare the energy differences between the sin gle-crystal and the energy-minimized structures for different conformations (trans/trans, trans/cis and cis/cis) of the thiophene rings and their bonded phen ring. The formation of an oligothiophene semiconductor polymer bridging gold electrodes with a gap of around 25 nm gap from RuII complex 7 by in situ electropolymerization, and its removal, is monitored by scanning electron microscopy (SEM). © Wiley-VCH Verlag GmbH & Co. KGaA.

DOI： 10.1002/ejic.200801131

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Films of chemically shortened and functionalized single-walled carbon nanotubes (SWNTs) have been formed on a gold electrode by electrophoretic deposition. Applying ultrasonic energy resulted in dramatic changes of the film morphology; the deposited SWNT bundles reassembled and oriented normal to the electrode. Oriented SWNT bundles with high density (more than 250 bundles/μm2) not only presented narrow size distributions, but uniformly spread on the electrode. We discuss the mechanism of SWNT orientation by analyzing the variation in the film morphology with ultrasonication time. In addition, we suggest that the 3D displays of AFM images can lead to misjudgment of nanotube alignment. The method for aligning SWNTs normal to the electrode may be competitive with chemical vapor deposition or screen printing, the predominant methods by which vertically aligned SWNT films have been fabricated to date. © 2008 American Chemical Society.

DOI： 10.1021/la802266y

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記述言語：英語   掲載種別：研究論文（学術雑誌）

3,8-Bis(3′4′-dibutyl-5″-mercapto-2,2′: 5′2″-termiophen-5-yl)-1,10-phenanthroline (2) with a molecular length of 3.36 nm and its Ru(II), Fe(II), and Cu(II) complexes were treated with tert-dodecanethiol-protected active gold nanoparticles (Au-NPs) in an average size of 3.3 nm in the presence of two facing Au electrodes with a 1 × 1 μm2 gap. Stable self-assembled molecular junctions were produced, wherein dithiols-bridged AuNPs were chemisorbed to the electrodes by means of Au-S-bonded contacts. SEM and AFM micrographs showed that different morphologies of the films were formed depending on the number of ligand 2 in the molecules and the coordination configurations of transition metal ions. Among them a relatively homogeneous granular thin film was obtained successfully in the case of the [Ru(bpy)2]2+ complex. Temperature-dependent current-voltage measurements for these junctions were performed in the temperature range of 8-300 K. The electronic conduction is dominated by the sum of tunneling and thermal excitation. Classical Arrhenius plots and their linear fits, wherein the temperature-independent tunneling current was deducted, were obtained to determine the average activation energies of these nanodevices. Photoresponsive properties of these self-assembled films were studied at different temperature (80, 160, and 300 K, respectively), where reversible and reproducible photoresponse can be recorded at room temperature in the presence of [Ru(bpy)2]2+ species. The comparison of results before and after metal-ion complexation reveals that the introduction of Ru(II) ion into the metal-molecule system can improve effectively the morphology of the self-assembled films and the overall conductivity, decrease the barrier for activation energy, and enhance the photoresponse of these nanodevices. © 2008 American Chemical Society.

DOI： 10.1021/jp711635p

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Oligothiophenes and porphyrin oligomers were exploited as new molecules for the "molecular ruler" (MR) method in the form of simple molecular monolayers. When handled in air, oligothiophenes yielded extremely homogeneous nanogaps about 30 nm wide, while handling under N2 produced nanoscale gaps of around 10 nm between parent and daughter structures. The difference between these two results indicated that it was possible to control the width of this gap by varying the extent of oxidation of the oligothiophenes. Porphyrin oligomers also yielded nanogaps about 10 nm wide. Therefore, these two types of molecules are promising candidates for use in the MR methods. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2007.05.045

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Two-dimensional crystals of [2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine] vanadium(IV) oxide and cobalt(II) (VOOEP and CoOEP, respectively) at the interface of 1-tetradecene and highly oriented pyretic graphite (HOPG) were studied by scanning tunneling microscopy (STM). The lattice parameters were determined for VOOEP (a = 1.61 ± 0.1 nm, b = 1.46 ± 0.05 nm, Γ = 61 ± 3°) and CoOEP (a = 1.48 ± 0.08 nm, b = 1.42 ± 0.07 nm, Γ = 62.0 ± 4°), which were calibrated using the HOPG lattice as a reference. The center metal dependence observed by high-resolution STM analysis of octaethylporphyrin and the differences between VOOEP and CoOEP are proved. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2007.05.073

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記述言語：英語   掲載種別：研究論文（学術雑誌）

A multistep synthesis was achieved to obtain 3,8-bis(4-mercaptophenyl)-1, 10-phenanthroline, which has two free thiol end groups with a molecular length of 1.89 nm, and its ruthenium(II) complex. Five single-crystal structures and UV-vis spectra of related intermediates in methanol and the solid state were studied in order to obtain additional information on the molecules as well as on the supramolecular interactions in the structures. Thermal and electrochemical properties of related Ru(II) complexes were also involved. 3,8-Bis(4- mercaptophenyl)-1,10-phenanthroline and one of its ruthenium(II) complexes were then treated with gold nanoparticles (Au-NPs) via in situ thiol-to-thiol ligand exchange in the presence of two facing Au electrodes with a 1 x 1 μm 2 gap. Stable molecular junctions composed of self-assembled films were produced as revealed by an obvious increase of the conductivity between the Au electrodes, wherein dithiols-bridged Au-NPs were attached to the electrodes by means of Au-S-bonded contacts. Temperature-dependent current-voltage (I-V) measurements for the junctions were performed in the temperature range of 7-300 K, and classical Arrhenius plots and their linear fits were obtained to determine the average activation energies (ΔE) of these devices. It is found that when the Ru(II) ion is introduced, the conductivity of the nanodevice is increased and the energy barrier is lowered under the same experimental conditions. © 2008 American Chemical Society.

DOI： 10.1021/ic701295q

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

We would like to share our recent results from a research on the single electron tunneling effect in a double-barrier tunneling junction (DBTJ) structure. Single Au nanoparticles were trapped in a nanogap electrodes, whose gap size was precisely controlled using a combination of electron beam lithography and molecular ruler technique. Here, we introduce how the novel combination technique was utilized to obtain the nanogap electrode. We also introduce the size effect of Au particles on the single electron tunneling behavior as a Coulomb island. Finally, we introduce the relation between the geometrical and electrical properties of the DBTJ.

DOI： 10.3131/jvsj2.51.428

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We investigated single electron tunneling (SET) behavior of dodecanethiol-coated Au nanoparticles of two different sizes (average sizes are 5 nm and 2 nm) using nanogap electrodes, which have a well-defined gap size, at various temperatures. The Coulomb staircases and the Coulomb gap near-zero bias voltage caused by the suppression of the tunneling electrons due to the Coulomb blockade effect were observed in the current-voltage (I-V) curves of both sizes of nanoparticles at a low temperature (10 K). At room temperature, the Coulomb gap was observed only in the I-V curve of the smaller nanoparticles. This result indicates that the charging energy of the smaller nanoparticles is enough to overcome the thermal energy at room temperature. This suggests that it is possible to operate the SET devices at room temperature using the smaller nanoparticles as a Coulomb island. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.susc.2007.04.039

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Electrodes with a gap size of 15 ∼ 80 nm could be bridged by porphyrin molecular wires with 50 ∼ 300 nm length. The porphyrin units could be coordinated with Au nano-particles having pyridinyl moiety. The device with both the porphyrin and Au nano-particles showed photo-response characteristics while those without the Au nano-particles showed no response. © Springer Science+Business Media, LLC 2007.

DOI： 10.1007/s10854-007-9262-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）

I-V characteristics of single electron tunneling from a symmetric and an asymmetric double-barrier tunneling junction (DBTJ) were examined. A single Au nanoparticle was trapped in nanogap whose size was precisely controlled using a combination of electron beam lithography and molecular ruler technique. Though the symmetric junction showed a monotonic rise with a bias beyond the Coulomb gap voltage, the asymmetric junction showed Coulomb staircases. The capacitance of the junction estimated from the fitting curves using the Coulomb conventional theory was consistent with the capacitance calculated from the observed structure. The authors quantitatively found the correlation between the electrical and structural properties of DBTJ. © 2007 American Institute of Physics.

DOI： 10.1063/1.2745252

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記述言語：英語   掲載種別：研究論文（学術雑誌）

A one-dimensional assembly of gold nanoparticles chemically bonded to jπ-conjugated porphyrin polymers was prepared on a chemically modified glass surface and on an undoped naturally oxidized silicon surface by the following methods: π-conjugated porphyrin polymers were prepared by oxidative coupling of 5,15-diethynyl-10,20-bis-((4-dendron)phenyl) porphyrin (6), and its homologues (larger than 40-mer) were collected by analytical gel permeation chromatography (GPC). The porphyrin polymers (>40-mer) were deposited using the Langmuir-Blodgett (LB) method on substrate surfaces, which were then soaked in a solution of gold nanoparticles (2.7 ±0.8 nm) protected with t-dodecanethiol and 4-pyridineethanethiol. The topographical images of the surface observed by tapping mode atomic force microscopy (AFM) showed that the polymers could be dispersed on both substrates, with a height of 2.8 ± 0.5 nm on the modified glass and 3.1 ± 0.5 nm on silicon. The height clearly increased after soaking in the gold nanoparticle solution, to 5.3 ± 0.5 nm on glass and 5.4 ± 0.7 nm on silicon. The differences in height (2.5 nm on glass and 2.3 nm on silicon) corresponded to the diameter of the gold nanoparticles bonded to the porphyrin polymers. The distance between gold nanoparticles observed in scanning electron microscopic images was ca. 5 nm, indicating that they were bonded at every four or five porphyrin units. © 2007 American Chemical Society.

DOI： 10.1021/la0634544

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

We have refined the measurement conditions of point-contact current imaging microscopy (PCI-AFM) to measure the electric properties along the long axes of one-dimensional structures. Using this refinement, the current image of the PCI-AFM can be used to distinguish individual single-walled carbon nanotubes in a bundled structure. The PCI-AFM will thus help further developments in nanoscience for conduction measurements in one-dimensional structures. © IOP Publishing Ltd.

DOI： 10.1088/0957-4484/18/9/095501

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

We report the first example of the isolated single chains of supramolecular porphyrin polymer, consisting of novel porphyrin dimer and bidentate ligand. In order to fabricate the isolated single chains on surface, the formation of supramolecular polymers was conducted at the air/water interface using a surfactant, and the transcription of these was performed by Langmuir-Blodgett method. A surfactant assisted the elongation of individual single chains, resulting in micrometer-long supramolecular polymers with molecularly uniform height on surface.

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

A simple method for fabricating periodic arrays of high aspect ratio (1:20) standing nanorods on silicon substrates is described. It is based on shadow deposition onto periodically arranged arrays of mini-rods on a rotating sample stage. Consequently, such nanostructures can be prepared on relatively large areas and at low cost, making the method suitable for industrial applications. © World Scientific Publishing Company.

DOI： 10.1142/S0219581X06005200

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

A simple method for the fabrication of sculptured thin films (STFs) of periodic arrays of high-aspect-ratio (20:1) standing nanorods on silicon substrates is described. It is based on oblique evaporation onto periodically arranged arrays of "mini-rod" topography using a rotating sample stage. 1 Recently, it has been shown that these nanostructures can be prepared on relatively large areas and at low cost, making the method suitable for technological applications. 2 Copyright © 2006 American Scientific Publishers All rights reserved.

DOI： 10.1166/jnn.2006.616

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

A nano-composite conductive film is formed between gold electrodes by immersion of the electrode pair in a chloroform solution of nonathiophenedithiol and gold nanoparticles. The homogeneous thin film is formed over an area of 3 mm × 3 mm surrounding the 1 m-gapped electrodes. The thickness of the film (20 nm) corresponds to 2-3 layers of the dithiol-bridged Au nanoparticles. Temperature-dependent I-V curves reveal that a thermionic mechanism dominates in the high-temperature region (80 K), while molecular tunneling is the main transport process at lower temperatures.

DOI： 10.1080/15421400600698774

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The electronic properties of a single-walled carbon nanotube/150mer of porphyrin polymer wire system were investigated. Current-voltage (I-V) curves were measured simultaneously along with topographic observations using point-contact current imaging atomic force microscopy. Symmetric I-V curves were obtained at bare single-walled carbon nanotubes but characteristic asymmetrical rectifying behavior was found at the single-walled carbon nanotube/150mer- porphyrin junctions. This finding is of key importance for the development of new nanoscale molecular electronic devices. Copyright © 2006 American Scientific Publishers All rights reserved.

DOI： 10.1166/jnn.2006.246

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We have developed and tested a new method of fabricating nanogaps using a combination of self-assembled molecular and electron beam lithographic techniques. The method enables us to control the gap size with an accuracy of approximately 2 nm and designate the positions where the nanogaps should be formed with high-resolution patterning by using electron beam lithography. We have demonstrated the utility of the fabricated nanogaps by measuring a single electron tunneling phenomenon through dodecanethiol-coated Au nanoparticles placed in the fabricated nanogap. © 2006 American Institute of Physics.

DOI： 10.1063/1.2209208

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記述言語：英語   掲載種別：研究論文（学術雑誌）

4-(S-Acetylthiomethyl)phenyl- and pyrenyl-functionalized π-conjugated porphyrin oligomers were synthesized. The distribution of the length of the oligomers could be controlled by changing the ratio of the starting porphyrin to the capping molecules. Oligomers from dimers to heptamers were isolated using size exclusion chromatography. The spectroscopic properties of these oligomers were measured to determine the influences of the number of porphyrin units and capping molecules on the absorption and emission spectra. © 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2006.03.031

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The fabrication of supramolecular porphyrin arrays on the surface of a mica substrate is demonstrated. The supramolecular structures are prepared at the air-water interface from a dilute solution of porphyrin dimer and bidentate ligand and then transferred to mica by using the conventional Langmuir-Blodgett method. Isolated wire-like structures and networks of structures are observed by atomic force microscopy. From the analysis of the height histogram and width, these structures are considered to be side-by-side arrangements of supramolecular chains of porphyrin dimer and bidentate ligand. By changing the ligand molecule, we demonstrate that the configuration of the supramolecular structure can be controlled. © 2006 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.45.2324

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Sub-micrometer long butadiyne-linked porphyrin wires were synthesized by oxidative coupling of diethynylporphyrin. The porphyrin wires were analyzed by analytical gel permeation chromatography, absorption spectroscopy and matrix-assisted laser desorption/ionization time of flight mass spectroscopy. Observations of the wire were performed by atomic force microscopy. Self-assembled structures of the wires were observed on highly oriented pyrolytic graphite. Self-assembling features of the porphyrin wires depended on the length of the porphyrin wires and the concentration of the depositing solution. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2005.07.143

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The preparation and properties of tert-dodecanethiol protected gold nanoparticles amenable to very rapid surface functionalization by associative mechanism is described. The new material can be easily prepared by controlling the reaction time, because only a limited but enough number of tertdodecanethiol to stabilize the gold clusters is bond to the surface until about an hour. Accordingly, it can be isolated as a solid and handled much like the highly stabilized Brust-Schiffrin analogues, but reacted very rapidly with any molecular species containing one or multiple functional groups such as thiol, disulfide, pyridine, etc., These characteristics are ideal for the preparation of a variety of new organic-inorganic hybrid nanomaterials by coordinative self-assembly. This possibility was illustrated using meso-tetra(4-pyridyl) porphyrin, which promptly bonded to the reactive protected gold nanoparticles generating a solid that can be grown as thin films with layer-by-layer control on a suitably modified surface. Copyright © 2006 American Scientific Publishers All rights reserved.

DOI： 10.1166/jnn.2006.079

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Three oligothiophene dithiols with different numbers of thiophene rings (3, 6 or 9) have been synthesized and characterized. The X-ray single crystal structures of terthiophene 2 and sexithiophene 5 are reported herein to show the exact molecular lengths, and ' to explain the difference between their UV-visible spectra arising from the different packing modes. These dithiols with different chain lengths were then treated with 2-dodecanethiol-protected active gold nanoparticles (Au-NPs) by means of in situ thiol-to-thiol ligand exchange in the presence of 1 μm gap Au electrodes. Thus the molecular junctions composed of self-assembled films were prepared, in which oligothio phene dithiol-bridged Au-NPs were attached to two electrodes by means of Au-S bonded contacts. The morphologies and current-voltage (I-V) characteristics of these films were studied by SEM and AFM approaches, which suggested that the thickness of the films (3-4 layers) varied within the size of one isolated Au-NP and typical distance-dependent semiconductor properties could be observed. Temperature dependent I-V measurements for these molecular junctions were performed in which the films served as active elements in the temperature range 6300 K ; classical Arrhenius plots and subsequent linear fits were carried out to give the activation energies (ΔE) of devices. Furthermore, preliminary studies on the photoresponsive properties of these devices were explored at 80, 160, and 300 K, respectively. Physical and photochemical mechanisms were used to explain the possible photocurrent generation processes. To the best of our knowledge, this is the first report in which oligothiophene dithiols act as bridging units to link Au-NPs. and also the first report about functionalized Au-NPs exhibiting photoresponse properties in the solid state. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/chem.200500822

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The molecular ruler method allows the precise control of the gap between a parent gold structure and a deposited daughter structure using a conveniently grown self-assembled molecular multilayer as a lithographic mask. However, we cannot choose a position where the gap should be placed, since the ruler attaches to all exposed gold surfaces. In this work, a convenient method of selecting the position of nanogaps by further patternine the molecular multilayer usine low-energy electron beam irradiation and piranha etchant is described.

DOI： 10.1143/JJAP.43.L950

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Stable junctions were obtained by preparing polymeric hexathienylphenanthroline wires coordinated to [RuII(bpy) 2](PF6)2 groups directly in Au electrode nanogaps by electropolymerization. Reproducible nonlinear and strongly temperature-dependent curves, similar to those found for self-assembled π-conjugated dithiols and diisocyanides inside nanoholes, were obtained rather than a tunneling behavior commonly found in alkanethiol self-assembled monolayers. This is the first time that a consistent series of data are collected for a polymer and interpreted based on a multicurve fitting method, based on the linear combination of tunneling, Frankel-Pool and hopping mechanims, indicating that various independent conduction pathways are present in the junctions.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

The developments in nanolithography were studied using molecular rulers process. This process utilizes the controlled placement and thickness of self-assembled multilayers. The combination of conventional lithographic technqiues with chemical self-assembly allows for the creation of nanostructures, whose spacing and edge resolution reach nanometer-scale precision. Fabrication techniques combining conventional nanolithography with chemical self-assembly allow for the feasible and parallel construction of nanostructures in the sub-100 nm regime.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

An overview is given on several means by which self-assembly processes can be utilized to pattern surfaces for technological applications. Hybridization of current nanofabrication techniques with selective chemical functionalization and methods are shown to be vital for the connection and application of molecular devices and also as an economical and parallel means to reach smaller scales in conventional electronic (and other) devices.

DOI： 10.1116/1.1515301

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Electronic band structure calculations based on the full-potential linear augmented plane-wave method have been performed for Fe16N2. The calculations are performed with the crystal parameters recently refined [H. Tanaka et al., Acta Mater. 45, 1401 (1997)] in addition to the previous reported structure [K. H. Jack, Proc. R. Soc. London, Ser. A 208, 200 (1951)]. Jack's model (J model) led to the model of Tanaka et al. (T model), where Fe atoms at the 8h site shift to N atoms along the [110] direction. The calculated average moment per Fe atom for the T model is slightly smaller than that for the J model. We cannot theoretically expect a large magnetic moment based on any Fe16N2 structure. The presence of another material that has a large magnetic moment must be considered to explain the large magnetic moment of the Fe-N system.

DOI： 10.1103/PhysRevB.62.15042

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開催期間： 2018年05月10日 - 2018年05月12日   記述言語：日本語  

開催期間： 2018年05月10日 - 2018年05月12日   記述言語：英語  

出願番号：特願平11-360274  出願日：1999年12月20日

公開番号：特開2001-174491  公開日：2001年06月29日

発表言語：英語   講演種別：招待講演  

発表言語：日本語   講演種別：招待講演   開催地：宇部市  

開催期間： 2023年09月26日 - 2023年09月27日   発表言語：日本語   講演種別：招待講演   開催地：北九州国際会議場  

開催期間： 2023年06月27日 - 2023年07月03日   発表言語：英語   講演種別：招待講演   開催地：VIT-AP University, online   国名：インド  

開催期間： 2023年06月11日 - 2023年06月12日   発表言語：英語   講演種別：招待講演   開催地：Kyuto  

開催期間： 2023年05月17日 - 2023年05月18日   発表言語：英語   講演種別：招待講演   開催地：AGH university   国名：ポーランド共和国  

開催期間： 2023年05月15日   発表言語：日本語   講演種別：その他  

発表言語：英語   講演種別：招待講演   開催地：Shinjuku, Tokyo   国名：日本国  

発表言語：日本語   講演種別：招待講演   開催地：名古屋大学   国名：日本国  

開催期間： 2023年02月28日 - 2023年03月03日   発表言語：英語   講演種別：特別講演   開催地：Ubon Ratchathani, Thailand   国名：タイ王国  

開催期間： 2022年12月10日 - 2022年12月12日   発表言語：英語   講演種別：招待講演   開催地：Kuala Lumpur   国名：マレーシア  

開催期間： 2022年12月08日 - 2022年12月09日   発表言語：英語   講演種別：招待講演   開催地：Tsukuba   国名：日本国  

開催期間： 2022年11月21日 - 2022年11月23日   発表言語：英語   講演種別：招待講演   開催地：Phu Quoc   国名：ベトナム社会主義共和国  

開催期間： 2022年10月20日 - 2022年10月21日   発表言語：英語   講演種別：特別講演   開催地：北九州学研都市会議場   国名：日本国  

開催期間： 2022年09月26日 - 2022年09月29日   発表言語：英語   講演種別：招待講演   開催地：Makuhari Messe, Chiba, Japan   国名：日本国  

開催期間： 2022年09月20日 - 2022年09月23日   発表言語：日本語   講演種別：招待講演   開催地：東北大学   国名：日本国  

開催期間： 2022年09月12日 - 2022年09月16日   発表言語：英語   講演種別：招待講演   開催地：Bento Gonssalves, RS   国名：ブラジル連邦共和国  

開催期間： 2022年08月30日 - 2022年08月31日   発表言語：日本語   講演種別：招待講演   開催地：遠隔   国名：日本国  

開催期間： 2022年07月07日 - 2022年07月08日   発表言語：英語   講演種別：招待講演   開催地：Ryukoku Univ./ Hybrid  

開催期間： 2022年03月06日 - 2022年03月10日   発表言語：英語   講演種別：招待講演   開催地：Nagoya University   国名：日本国  

発表言語：英語   講演種別：特別講演   開催地：Online  

発表言語：日本語   講演種別：招待講演   開催地：東京理科大と遠隔接続  

発表言語：日本語   講演種別：招待講演   開催地：遠隔  

発表言語：英語   講演種別：招待講演  

発表言語：英語   講演種別：招待講演  

発表言語：日本語   講演種別：招待講演   開催地：遠隔  

発表言語：日本語   講演種別：招待講演   開催地：遠隔  

https://meeting.jsap.or.jp/invited-speakers

発表言語：日本語   講演種別：招待講演   開催地：遠隔  

発表言語：英語   講演種別：招待講演  

発表言語：英語   講演種別：招待講演  

講演種別：招待講演   開催地：UCLA  

発表言語：英語   講演種別：招待講演   開催地：Ataturk University (online)  

開催期間： 2021年04月07日 - 2021年04月09日   発表言語：英語   講演種別：招待講演   開催地：Ataturk University, Turkey  

発表言語：英語   講演種別：招待講演   開催地：Chengmai, Thailand (online)  

発表言語：英語   講演種別：招待講演   開催地：北九州学術研究都市  

発表言語：日本語   講演種別：特別講演   開催地：北九州学研都市会議場  

発表言語：日本語   講演種別：招待講演   開催地：遠隔  

近年深層学習の優れた計算能力が広く認知され、人工知能の実応用が急速に広がっている。一方で、人工知能アルゴリズムを実行するハードウェアは、シリコンCMOS技術のスケーリングの物理的限界に直面し、性能向上は頭打ちが予想される。このため神経情報処理系である人工ニューラルネットワーク（ANN）やその応用形である深層学習システム（以下本稿ではこれらを人工知能システムと呼ぶ）を物理的に実装するハードウェア技術とそれを支える新しい材料・デバイスへの関心が高まっている。求められるデバイス機能として、従来の計算システムと決定的に異なるのは、ダイナミクスの利用である。ナノマテリアルの非線形性やネットワーク構造を巧みに用いることで、自発的にパルスやノイズを発生するデバイスの実現が期待される。これらのデバイスは人工知能システムの飛躍的な低消費電力化や高集積化を可能とする。また、ANNの学習プロセスでは重み付き加算（積和演算）部分の重みを絶えず変更し記憶する必要性があり、これに代わる電力消費量の小さいデバイスも求められる。我々は分子やナノカーボンマテリアルを用い、ANNに置き換わる機能を実現する材料研究を進めている。本稿ではこれらナノマテリアルとネットワークの形成、機能化のポイント、および我々の最近の研究成果について紹介する。

発表言語：日本語   講演種別：その他   開催地：遠隔  

開催期間： 2020年09月08日 - 2020年09月11日   発表言語：日本語   講演種別：招待講演   開催地：遠隔  

リカレントニューラルネットワーク（RNN）の一種であるリザバー演算は、多電極からの出力重みの学習のみを必要とするため、エネルギー効率が高くより速い予測や分類タスクを行えると期待されている。非線形性、メモリ効果、高次元性といったリザバーの特性を反映した物理的なハードウェアプラットフォームは、現状 AI システムで標準的に使われているソフトウェアベースのインターフェースに代替できるとして注目されている。本研究では、我々がすでにリザバーとしての有効性を確認している単層カ ーボンナノチューブ(SWNT)/ポリオキソメタレート集合体[1]、Ag/Ag2S 微粒子集合体、Ag/Ag2Se ナノワイヤー集合体など多様な材料を利用したランダムネットワーク（RNW）を構築し物理的リザバーとした際の電気測定結果を紹介する。また、波形生成と非線形自己回帰移動平均(NARMA)時系列予測の 2つのベンチマークタスクの結果を比較し、どの材料がリザバー演算にとって有効なのか検討する。

発表言語：英語   講演種別：招待講演   開催地：FAIS  

発表言語：英語   講演種別：招待講演  

発表言語：英語   講演種別：基調講演   開催地：Ho Chi Minh City University of Technology  

発表言語：英語   講演種別：特別講演  

発表言語：英語   講演種別：招待講演   開催地：Pattaya  

発表言語：英語   講演種別：招待講演   開催地：Osaka University  

開催期間： 2014年11月04日 - 2014年11月07日   発表言語：英語   講演種別：特別講演   開催地：Hilton Fukuoka Sea Hawk  

開催期間： 2014年10月09日   発表言語：英語   講演種別：特別講演  

開催期間： 2014年10月02日   発表言語：英語   講演種別：特別講演  

開催期間： 2014年09月26日 - 2014年09月28日   発表言語：英語   講演種別：特別講演  

受賞国：日本国