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Abstract: An international research team at Tohoku University's Advanced Institute of Materials Research (AIMR) succeeded in chemically interconnecting chiral-edge graphene nanoribbons (GNRs) with zigzag-edge features by molecular assembly, and demonstrated electronic connection between GNRs. The GNRs were interconnected exclusively end to end, forming elbow structures, identified as interconnection points (Fig. 1a). This configuration enabled researchers to demonstrate that the electronic architecture at the interconnection points between two GNRs (Fig. 1b) is the same as that along single GNRs; evidence that GNR electronic properties, such as electron and thermal conductivities, are directly extended through the elbow structures upon chemical GNR interconnection. This work shows that future development of high-performance, low-power-consumption electronics based on GNRs is possible. Graphene has long been expected to revolutionize electronics, provided that it can be cut into atomically precise shapes that are connected to desired electrodes. However, while current bottom-up fabrication methods can control graphene's electronic properties, such as high electron mobility, tailored band gaps and s pin-aligned zigzag edges, the connection aspect of graphene structures has never been directly explored. For example, whether electrons traveling across the interconnection points of two GNRs would encounter higher electric resistance remains an open question. As the answers to this type of questions are crucial towards the realization of future high-speed, low-power-consumption electronics, we use molecular assembly to address this issue here. "Current molecular assemblies either produce straight GNRs (i.e., without identifiable interconnection points), or randomly interconnected GNRs," says Dr. Patrick Han, the project leader. "These growth modes have too many intrinsic unknowns for determining whether electrons travel across graphene interconnection points smoothly. The key is to design a molecular assembly that produces GNRs that are systematically interconnected with clearly distinguishable interconnection points." To reach this goal, the AIMR team used a Cu substrate, whose reactivity confines the GNR growth to six directions, and used scanning tunneling microscopy (STM) to visualize the GNR electronic structures. By controlling the precursor molecular coverage, this molecular assembly connects GNRs from different growth directions systematically end to end, producing elbow structures--identified as interconnection points (Fig. 1a). Using STM, the AIMR team revealed that the delocalization of the interconnected GNR π*-states extends the same way both across a single straight GNR, and across the interconnection point of two GNRs (periodic features in Fig. 1b, bottom panel). This result indicates that GNR electronic properties, such as electron and thermal conductivities, should be the same at the termini of single GNRs and that of two connected GNRs. "The major finding of this work is that interconnected GNRs do not show electronic disruption (e.g., electron localization that increases resistance at the interconnection points)," says Han. "The electronically smooth interconnection demonstrates that GNR properties (including tailored band gaps, or even spin-aligned zigzag edges) can be connected to other graphene structures. These results show that finding a way to connect defect-free GNRs to desired electrodes may be the key strategy toward achieving high-performance, low-power-consumption electronics." About Tohoku University The Advanced Institute for Materials Research (AIMR) at Tohoku University is one of nine World Premier International Research Center Initiative (WPI) Programs established with the support of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The program aims to develop world-class research bases in Japan. After its establishment in 2007, AIMR has been active in conducting research activities and creating new systems in order to become a global center for materials science. Since 2012, AIMR has also been conducting fundamental research by finding connections between materials science and mathematics. Learn more at www.wpi-aimr.tohoku.ac.jp For more information, please click Contacts: Patrick Han 81-222-176-170 For information on AIMR and all other enquiries: Marie Minagawa Public Relations & Outreach office Advanced Institute for Materials Research, Tohoku University aimr-outreachgrp.tohoku.ac.jp Fax: +81-22-217-6146 If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Velghe I.,NuTeC | Velghe I.,Hasselt University | Carleer R.,Hasselt University | Yperman J.,Hasselt University | And 2 more authors.
Water Research | Year: 2012

Copper and zinc removal from water (pH = 5.0) using adsorbents produced from slow and fast pyrolysis of industrial sludge and industrial sludge mixed with a disposal filter cake (FC), post treated with HCl, is investigated in comparison with a commercial adsorbent F400. The results show that a pseudo-second order kinetics model is followed. The Langmuir-Freundlich isotherm model is found to fit the data best. The capacity for heavy metal removal of studied adsorbents is generally better than that of commercial F400. The dominant heavy metal removal mechanism is cation exchange. Higher heavy metal removal capacity is associated with fast pyrolysis adsorbents and sludge/FC derived adsorbents, due to enhanced cation exchange. Improvement of Zn 2+ removal via 1 N HCl post-treatment is only effective when exchangeable cations of the adsorbent are substituted with H + ions, which boost the cation exchange capacity. Increase of temperature also enhances metal removal capacity. Fast pyrolysis sludge-based adsorbents can be reused after several adsorption-desorption cycles. © 2012 Elsevier Ltd.


Wu G.,Shanghai JiaoTong University | Teng N.-G.,Shanghai JiaoTong University | Wang Y.,Institute for Materials Research
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The laboratory tests are performed to study the physical and mechanical properties of Jiaozuo limestone after undergoing different high temperatures. The temperature varies in the range of 100°C, 200°C, 400°C, 600°C and 800°C. The scopes of this study include the description of apparent shape, the measurement of volume, mass and density and the detection of longitudinal wave and shear wave of limestone. The peak stress, peak strain and Young's modulus of limestone are also investigated under the uniaxial compression. The factors of degradation of limestone under high temperatures are discussed. The test results show that the high temperatures lead to variation of the apparent shape for limestone. The temperatures do not obviously affect the physical and mechanical properties of limestone below 400°C. The volume of limestone reduces slightly below 200°C, but increases obviously over 200°C. Meanwhile, the density of limestone decreases gradually with the increase of the temperatures. As the temperatures increase, the S-wave velocity and the P-wave velocity for limestone generally decrease. The variation of ratio of wave velocity for limestone is irregular after high temperature. The dynamic elastic modulus of limestone after high temperature decreases with the increase of the temperatures. When the temperature is above 400°C, the mechanical properties of limestone exhibit deterioration with the increase of the temperature, and the peak stress and Young's modulus of limestone decrease to different extents. The variation of the peak strain of limestone is unconspicuous before 800°C. The thermal stress, variations of mineral formation and microstructure due to the temperatures result in the variation of physical and mechanical properties and degradation of limestone.


News Article | December 13, 2016
Site: www.eurekalert.org

Scientists in Japan have revealed that if a glassy solid possesses a planar (sheet-like) structure, it can exhibit enhanced thermal vibration motion due to the same mechanism known for the planar crystals (two-dimensional crystals), by using large-scale simulations on supercomputers. "Imagine if we could make a sheet of glass, which has a two-dimensional (2D) planate shape," says Dr. Hayato Shiba, of Tohoku University's Institute for Materials Research (IMR). "In such a confined spatial dimension, a variety of novel phenomena takes place in usual "periodic" systems (crystals, spin systems etc.). This is due to the thermal motion of the constituents taking place on a larger scale because of the limited spatial dimensions." Such enhanced thermal motion is known to induce new physical phenomena which Shiba, and his research team of Yasunori Yamada (IMR), Takeshi Kawasaki (Nagoya University) and Kang Kim (Osaka University), hope will lead the development of new functional materials and devices necessary for the realization of energy-saving societies. However, it is still uncertain whether 2D glass, as an "non-periodic" system, exhibits such enhanced thermal motions. "Our result indicates that 2D glass can become soft, gradually and forever, as we go to the macroscopic scales. Consequently, the vibration amplitude becomes infinite because of the large-scale motions," says Shiba. "In other words, such materials might exhibit strong responses to external fields or deformation. The thermal vibration is perfectly different from that in a 3D glass, and it can even alter the fundamental nature of vitrification and glassy phase transition." In the experiments, 2D glass was experimentally realized using colloidal systems, and can also be realized using other soft and hard materials.


News Article | December 15, 2016
Site: www.cemag.us

Scientists in Japan have revealed that if a glassy solid possesses a planar (sheet-like) structure, it can exhibit enhanced thermal vibration motion due to the same mechanism known for the planar crystals (two-dimensional crystals), by using large-scale simulations on supercomputers. "Imagine if we could make a sheet of glass, which has a two-dimensional (2D) planate shape," says Dr. Hayato Shiba, of Tohoku University's Institute for Materials Research (IMR). "In such a confined spatial dimension, a variety of novel phenomena takes place in usual "periodic" systems (crystals, spin systems etc.). This is due to the thermal motion of the constituents taking place on a larger scale because of the limited spatial dimensions." Such enhanced thermal motion is known to induce new physical phenomena which Shiba, and his research team of Yasunori Yamada (IMR), Takeshi Kawasaki (Nagoya University) and Kang Kim (Osaka University), hope will lead the development of new functional materials and devices necessary for the realization of energy-saving societies. However, it is still uncertain whether 2D glass, as an "non-periodic" system, exhibits such enhanced thermal motions. "Our result indicates that 2D glass can become soft, gradually and forever, as we go to the macroscopic scales. Consequently, the vibration amplitude becomes infinite because of the large-scale motions," says Shiba. "In other words, such materials might exhibit strong responses to external fields or deformation. The thermal vibration is perfectly different from that in a 3D glass, and it can even alter the fundamental nature of vitrification and glassy phase transition." In the experiments, 2D glass was experimentally realized using colloidal systems, and can also be realized using other soft and hard materials.


News Article | December 15, 2016
Site: www.cemag.us

Scientists in Japan have revealed that if a glassy solid possesses a planar (sheet-like) structure, it can exhibit enhanced thermal vibration motion due to the same mechanism known for the planar crystals (two-dimensional crystals), by using large-scale simulations on supercomputers. "Imagine if we could make a sheet of glass, which has a two-dimensional (2D) planate shape," says Dr. Hayato Shiba, of Tohoku University's Institute for Materials Research (IMR). "In such a confined spatial dimension, a variety of novel phenomena takes place in usual "periodic" systems (crystals, spin systems etc.). This is due to the thermal motion of the constituents taking place on a larger scale because of the limited spatial dimensions." Such enhanced thermal motion is known to induce new physical phenomena which Shiba, and his research team of Yasunori Yamada (IMR), Takeshi Kawasaki (Nagoya University) and Kang Kim (Osaka University), hope will lead the development of new functional materials and devices necessary for the realization of energy-saving societies. However, it is still uncertain whether 2D glass, as an "non-periodic" system, exhibits such enhanced thermal motions. "Our result indicates that 2D glass can become soft, gradually and forever, as we go to the macroscopic scales. Consequently, the vibration amplitude becomes infinite because of the large-scale motions," says Shiba. "In other words, such materials might exhibit strong responses to external fields or deformation. The thermal vibration is perfectly different from that in a 3D glass, and it can even alter the fundamental nature of vitrification and glassy phase transition." In the experiments, 2D glass was experimentally realized using colloidal systems, and can also be realized using other soft and hard materials.


News Article | December 13, 2016
Site: phys.org

"Imagine if we could make a sheet of glass, which has a two-dimensional (2D) planate shape," says Dr. Hayato Shiba, of Tohoku University's Institute for Materials Research (IMR). "In such a confined spatial dimension, a variety of novel phenomena takes place in usual "periodic" systems (crystals, spin systems etc.). This is due to the thermal motion of the constituents taking place on a larger scale because of the limited spatial dimensions." Such enhanced thermal motion is known to induce new physical phenomena which Shiba, and his research team of Yasunori Yamada (IMR), Takeshi Kawasaki (Nagoya University) and Kang Kim (Osaka University), hope will lead the development of new functional materials and devices necessary for the realization of energy-saving societies. However, it is still uncertain whether 2D glass, as an "non-periodic" system, exhibits such enhanced thermal motions. "Our result indicates that 2D glass can become soft, gradually and forever, as we go to the macroscopic scales. Consequently, the vibration amplitude becomes infinite because of the large-scale motions," says Shiba. "In other words, such materials might exhibit strong responses to external fields or deformation. The thermal vibration is perfectly different from that in a 3D glass, and it can even alter the fundamental nature of vitrification and glassy phase transition." In the experiments, 2D glass was experimentally realized using colloidal systems, and can also be realized using other soft and hard materials. Explore further: Memories and energy landscapes of magnetic glassy states More information: Hayato Shiba et al, Unveiling Dimensionality Dependence of Glassy Dynamics: 2D Infinite Fluctuation Eclipses Inherent Structural Relaxation, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.117.245701


Yamauchi M.,International Institute for Carbon Neutral Energy Research WPI I2CNER | Ozawa N.,Institute for Materials Research | Kubo M.,Institute for Materials Research
Chemical Record | Year: 2016

Renewable electricity must be utilized to usefully suppress the atmospheric CO2 concentration and slow the progression of global warming. We have thus proposed a new concept involving CO2-free electric power circulation systems via highly selective electrochemical reactions of alcohol/carboxylic acid redox couples. Design concepts for nanocatalysts able to catalyze highly selective electrochemical reactions are provided from both experimental and quantum mechanical perspectives. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Venkataramanan N.S.,Institute for Materials Research
International Journal of Quantum Chemistry | Year: 2012

The structure and stability for the association of water with dimethyl sulfoxide (DMSO) are investigated using the density functional M06-2X level theory. Stable complexes are formed by the formation of hydrogen bonding between water and oxygen atom of DMSO molecule, while the electrostatic force between water and DMSO plays a vital role in deciding the structure. The water-DMSO interactions are stronger than the interwater hydrogen bonds, which can be inferred from the shorter DMSO-water bond distance compared with the water-water bond distance. The calculated solvent association energy does not saturate, and it remains favorable to attach additional water molecules to the existing water network. The calculated IR spectra shifts supports the formation stronger hydrogen bonding, while the electrostatic potential (ESP) plot supports the existence of weaker electrostatic interaction in the studied clusters. The polarizabilities for the ground state clusters were found to increase monotonically with the cluster size. The presence of additional electrostatic bonding between water and DMSO, devastates the linear hydrogen-bonding network. Copyright © 2011 Wiley Periodicals, Inc.


De Schepper E.,Hasselt University | Van Passel S.,Hasselt University | Manca J.,Institute for Materials Research | Thewys T.,Hasselt University
Renewable Energy | Year: 2012

In the light of global warming, renewables such as solar photovoltaics (PV) are important to decrease greenhouse gas emissions. An important issue regarding implementation of solar panels on large scale, is the limited available area. Therefore, it can be interesting to combine PV with alternative applications, as a ways of not requiring " additional" space. One example is a photovoltaic noise barrier (PVNB), where a noise barrier located along a highway or railway is used as substructure for PV modules. Even though a PVNB is not a novel concept, the absence of economic assessments in literature can be a barrier to their wider implementation.In this paper, a feasibility study of a PVNB in Belgium is conducted, using a cost benefit analysis including a Monte Carlo sensitivity analysis. Besides purely economic aspects, also ecological benefits are monetized. The sensitivity analysis indicates that the ecological benefit of noise reduction, which is valuated using a noise sensitivity depreciation index applied to real estate prices, is of major importance in determining the net present value of the case study. On the contrary, the impact of reducing CO 2 emissions seems to be negligible when expressed in monetary terms. The results suggest that the PVNB as a whole and also its separate components -i.e. the PV array and the noise barrier- can be profitable projects, when ecological benefits are included. © 2012 Elsevier Ltd.

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