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Showing papers by "National Institute of Advanced Industrial Science and Technology published in 2008"


Journal ArticleDOI
TL;DR: The lithium storage properties of graphene nanosheet (GNS) materials as high capacity anode materials for rechargeable lithium secondary batteries (LIB) were investigated and the specific capacity of GNS was found to be 540 mAh/g, which is much larger than that of graphite, and this was increased by the incorporation of macromolecules of CNT and C60 to the GNS.
Abstract: The lithium storage properties of graphene nanosheet (GNS) materials as high capacity anode materials for rechargeable lithium secondary batteries (LIB) were investigated. Graphite is a practical anode material used for LIB, because of its capability for reversible lithium ion intercalation in the layered crystals, and the structural similarities of GNS to graphite may provide another type of intercalation anode compound. While the accommodation of lithium in these layered compounds is influenced by the layer spacing between the graphene nanosheets, control of the intergraphene sheet distance through interacting molecules such as carbon nanotubes (CNT) or fullerenes (C60) might be crucial for enhancement of the storage capacity. The specific capacity of GNS was found to be 540 mAh/g, which is much larger than that of graphite, and this was increased up to 730 mAh/g and 784 mAh/g, respectively, by the incorporation of macromolecules of CNT and C60 to the GNS.

2,692 citations


Journal ArticleDOI
TL;DR: In this paper, the authors review the current status of one of the alternatives, resistance random access memory (ReRAM), which uses a resistive switching phenomenon found in transition metal oxides.

2,641 citations


Journal ArticleDOI
TL;DR: Porous carbon was synthesized by heating the precursor FA within the pores of MOF-5 to display a high specific surface area and important hydrogen uptake and excellent electrochemical properties as an electrode material for electrochemical double-layered capacitor (EDLC).
Abstract: Porous carbon was synthesized by heating the precursor FA within the pores of MOF-5. The resultant carbon displayed a high specific surface area (BET, 2872 m2·g−1) and important hydrogen uptake (2.6 wt % at 760 Torr, −196 °C) as well as excellent electrochemical properties as an electrode material for electrochemical double-layered capacitor (EDLC).

1,538 citations


Journal ArticleDOI
TL;DR: The plasmonic photocatalysis will be of use as a high performance photocatalyst in nearly all current applications but will beof particular importance for applications in locations of minimal light exposure.
Abstract: Titanium dioxide (TiO2) displays photocatalytic behavior under near-ultraviolet (UV) illumination. In another scientific field, it is well understood that the excitation of localized plasmon polaritons on the surface of silver (Ag) nanoparticles (NPs) causes a tremendous increase of the near-field amplitude at well-defined wavelengths in the near UV. The exact resonance wavelength depends on the shape and the dielectric environment of the NPs. We expected that the photocatalytic behavior of TiO2 would be greatly boosted if it gets assisted by the enhanced near-field amplitudes of localized surface plasmon (LSP). Here we show that this is true indeed. We named this new phenomenon "plasmonic photocatalysis". The key to enable plasmonic photocatalysis is to deposit TiO2 on a NP comprising an Ag core covered with a silica (SiO2) shell to prevent oxidation of Ag by direct contact with TiO2. The most appropriate diameter for Ag NPs and thickness for the SiO2 shell giving rise to LSP in the near UV were estimated from Mie scattering theory. Upon implementing a device that took these design considerations into account, the measured photocatalytic activity under near UV illumination of such a plasmonic photocatalyst, monitored by decomposition of methylene blue, was enhanced by a factor of 7. The enhancement of the photocatalytic activity increases with a decreased thickness of the SiO2 shell. The plasmonic photocatalysis will be of use as a high performance photocatalyst in nearly all current applications but will be of particular importance for applications in locations of minimal light exposure.

1,422 citations


Journal ArticleDOI
12 Sep 2008-Science
TL;DR: It is found that the SWNT content can be increased up to 20 weight percent without reducing the mechanical flexibility or softness of the copolymer, and the elastic conductor allows for the construction of electronic integrated circuits, which can be mounted anywhere, including arbitrary curved surfaces and movable parts, such as the joints of a robot's arm.
Abstract: By using an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, we uniformly dispersed single-walled carbon nanotubes (SWNTs) as chemically stable dopants in a vinylidene fluoride-hexafluoropropylene copolymer matrix to form a composite film. We found that the SWNT content can be increased up to 20 weight percent without reducing the mechanical flexibility or softness of the copolymer. The SWNT composite film was coated with dimethyl-siloxane-based rubber, which exhibited a conductivity of 57 siemens per centimeter and a stretchability of 134%. Further, the elastic conductor was integrated with printed organic transistors to fabricate a rubberlike active matrix with an effective area of 20 by 20 square centimeters. The active matrix sheet can be uniaxially and biaxially stretched by 70% without mechanical or electrical damage. The elastic conductor allows for the construction of electronic integrated circuits, which can be mounted anywhere, including arbitrary curved surfaces and movable parts, such as the joints of a robot's arm.

1,330 citations


Journal ArticleDOI
TL;DR: The carbon catalyst can be readily separated from the saccharide solution after reaction for reuse in the reaction without loss of activity, and the catalytic performance of the carbon catalyst is attributed to the ability of the material to adsorb beta-1,4 glucan, which does not adsorb to other solid acids.
Abstract: The hydrolysis of cellulose into saccharides using a range of solid catalysts is investigated for potential application in the environmentally benign saccharification of cellulose. Crystalline pure cellulose is not hydrolyzed by conventional strong solid Bronsted acid catalysts such as niobic acid, H-mordenite, Nafion and Amberlyst-15, whereas amorphous carbon bearing SO 3H, COOH, and OH function as an efficient catalyst for the reaction. The apparent activation energy for the hydrolysis of cellulose into glucose using the carbon catalyst is estimated to be 110 kJ mol (-1), smaller than that for sulfuric acid under optimal conditions (170 kJ mol (-1)). The carbon catalyst can be readily separated from the saccharide solution after reaction for reuse in the reaction without loss of activity. The catalytic performance of the carbon catalyst is attributed to the ability of the material to adsorb beta-1,4 glucan, which does not adsorb to other solid acids.

918 citations


Journal ArticleDOI
TL;DR: The results suggest that FIP200 is a novel mammalian autophagy factor that functions together with ULKs, which regulates diverse cellular functions such as cell size, proliferation, and migration.
Abstract: Autophagy is a membrane-mediated intracellular degradation system. The serine/threonine kinase Atg1 plays an essential role in autophagosome formation. However, the role of the mammalian Atg1 homologues UNC-51–like kinase (ULK) 1 and 2 are not yet well understood. We found that murine ULK1 and 2 localized to autophagic isolation membrane under starvation conditions. Kinase-dead alleles of ULK1 and 2 exerted a dominant-negative effect on autophagosome formation, suggesting that ULK kinase activity is important for autophagy. We next screened for ULK binding proteins and identified the focal adhesion kinase family interacting protein of 200 kD (FIP200), which regulates diverse cellular functions such as cell size, proliferation, and migration. We found that FIP200 was redistributed from the cytoplasm to the isolation membrane under starvation conditions. In FIP200-deficient cells, autophagy induction by various treatments was abolished, and both stability and phosphorylation of ULK1 were impaired. These results suggest that FIP200 is a novel mammalian autophagy factor that functions together with ULKs.

880 citations


Journal ArticleDOI
TL;DR: An in situ polymerization restriction method is reported for the synthesis of a nano-sized LiFePO4/carbon composite with a core–shell structure from Fe salts, considered to be one of the most promising cathode materials for the next generation of lithium batteries.
Abstract: Nano-sized electrode materials for lithium-ion batteries have attracted much attention recently because their reduced dimensions enable much higher power. However, the large electrolyte/electrode interface arising from their size leads to more undesired reactions, which result in poor cycling performance. Moreover, some nano-sized cathode materials synthesized by low-temperature methods are poorly crystalline, which also reduces their electrochemical stability. The synthesis of highly crystalline nanomaterials completely coated with conductive carbon (or a carbon shell) would be an effective means of eliminating these problems. Such a synthesis is a significant challenge, however, as the highly crystalline structure and its subsequent coating with conductive carbon have to be achieved at high temperature, where larger crystallite sizes are almost inevitable. Olivine (LiFePO4) is considered to be one of the most promising cathode materials for the next generation of lithium batteries due to its low toxicity, low cost, and high safety. However, its power performance is greatly limited by slow diffusion of lithium ions across the two-phase boundary and/or low conductivity. Many efforts have been made over the past few years to improve the power performance of LiFePO4 by using low-temperature routes to obtain tailored particles or carbon painting to improve the conductivity of the solid phase. However, these previous studies have always focused on the “nano-size” or the “coating with conductive carbon” separately, rather than considering both of them together. Various low-temperature methods (synthesis temperature below 600 8C), such as lowtemperature ceramic routes or hydrothermal syntheses, have been developed to lower the particle size of LiFePO4, although none of them have been able to ensure the conductivity of the carbon coating. Furthermore, some lowtemperature routes are not able to produce the required highly crystalline olivine structure, thus reducing the electrochemical stability of LiFePO4. The high surface area arising from the nano-size of the products also greatly increases the undesirable electrode/electrolyte reactions, which leads to a poor cycling performance From a review of previous studies of nano-sized LiFePO4 (less than 100 nm), we can see that a “perfect” cycle-life (> 200 cycles) at high charge/ discharge depth (90%) is almost unheard of. Approaches based on the thermal decomposition of carbon-containing precursors have also been widely studied for the preparation of carbon-coated LiFePO4 particles. [16–23] However, these methods generally involve a high-temperature treatment, during which an increase in crystallite size is inevitable, to ensure the conductivity of the resulting carbon materials. Accordingly, those approaches based on the thermal decomposition of carbon-containing precursors can only produce LiFePO4 particles with a partial coating of carbon (Figure 1a). As shown in Figure 1a, during the intercalation process, the electrons cannot reach all the positions where Li ion intercalation takes place, thus resulting in polarization of the electrode. In view of the one-dimensional Li ion mobility in the framework, full coating with carbon, which ensures LiFePO4 particles get electrons from all directions, could further alleviate this polarization phenomenon. According to our analysis of previous studies, the ideal structure for high-performance LiFePO4 should contain nano-size particles completely coated with conductive carbon (Figure 1b). It should be noted that many previous studies involving the synthesis of nano-sized LiFePO4 employ Fe 2+ salts as precursors. 11–13,21] However, these salts are much more expensive and unstable than Fe salts, therefore the synthesis of a nano-sized LiFePO4/carbon composite with a core–shell structure from Fe salts would be of great interest. Herein we report an in situ polymerization restriction method for the synthesis of a LiFePO4/carbon composite formed from a highly crystalline LiFePO4 core with a size of about 20–40 nm and a semi-graphitic carbon shell with a thickness of about 1–2 nm. As shown in Figure 1c, our strategy includes one in situ polymerization reaction and two typical restriction processes. The first of these restriction processes involves the addition of Fe ions to a solution containing PO4 3 ions and aniline, where it acts as both a precipitator for PO4 3 and oxidant for aniline. The reaction during this process can be summarized as Equations (1) and (2).

857 citations


Journal ArticleDOI
TL;DR: In this paper, the photovoltaic performance of dye-sensitized solar cells (DSSCs) was improved by adding n-hexyl chains to the thiophene groups.
Abstract: Novel organic dyes (MK dyes), which have a carbazole derivative as an electron donor and a cyanoacrylic acid moiety (═C(—C≡N)COOH) as an electron acceptor and an anchoring group, connected with n-hexyl-substituted oligothiophenes as a π-conjugated system, were designed and synthesized for application in dye-sensitized solar cells (DSSCs), which are one of the promising molecular photovoltaics. The photovoltaic performance of the DSSCs based on MK dyes markedly depends on the molecular structure of the dyes in terms of the number and position of n-hexyl chains and the number of thiophene moieties. Retardation of charge recombination caused by the existence of n-hexyl chains linked to the thiophene groups resulted in an increase in electron lifetime. As a consequence, an improvement of open-circuit photovoltage (Voc) and hence the solar-to-electric power conversion efficiency (η) of DSSCs was achieved upon addition of n-hexyl chains to the thiophene groups. In addition, the adsorption condition (amount of d...

607 citations


Journal ArticleDOI
TL;DR: The most efficient photocatalytic system was successfully developed using a mixed system with fac-[Re(bpy)(CO)3(CH3CN)]+ and fac-[4,4'-(MeO)2bpy}( CO)3{P(OEt)3}]+, for which the optimized quantum yield for CO formation was 0.59.
Abstract: The reaction mechanism of photocatalytic CO2 reduction using rhenium(I) complexes has been investigated by means of a detailed comparison of the photocatalyses of three rhenium(I) complexes, fac-[Re(bpy)(CO)3L] (L = SCN- (1-NCS), Cl- (1-Cl), and CN- (1-CN)). The corresponding one-electron-reduced species (OER) of the complexes play two important roles in the reaction: (a) capturing CO2 after loss of the monodentate ligand (L) and (b) donation of the second electron to CO2 by another OER without loss of L. In the case of 1-NCS, the corresponding OER has both of the capabilities in the photocatalytic reaction, resulting in more efficient CO formation (with a quantum yield of 0.30) than that of 1-Cl (quantum yield of 0.16), for which OER species have too short a lifetime to accumulate during the photocatalytic reaction. On the other hand, 1-CN showed no photocatalytic ability, because the corresponding OER species does not dissociate the CN- ligand. Based on this mechanistic information, the most efficient ...

541 citations


Journal ArticleDOI
TL;DR: Quantitative measurement of voltage dependence of spin-transfer torque in MgO-based magnetic tunnel junctions was performed in this paper, where the spin transfer torque was measured in terms of voltage.
Abstract: Quantitative measurement of voltage dependence of spin-transfer torque in MgO-based magnetic tunnel junctions

Journal ArticleDOI
TL;DR: In this article, the fundamental issues associated with solid oxide fuel cell (SOFC) durability have been reviewed with an emphasis on general features in SOFCs and respective anode and cathode related phenomena.

Journal ArticleDOI
TL;DR: In this article, the superconducting phase diagram of NdFeAsO 1- y was established as a function of oxygen content, which was determined by Rietveld refinement.
Abstract: The crystal structure of LnFeAsO 1- y (Ln = La, Nd) has been studied by the powder neutron diffraction technique. The superconducting phase diagram of NdFeAsO 1- y is established as a function of oxygen content which is determined by Rietveld refinement. The small As–Fe bond length suggests that As and Fe atoms are connected covalently. FeAs 4 -tetrahedrons transform toward a regular shape with increasing oxygen deficiency. Superconducting transition temperatures seem to attain maximum values for regular FeAs 4 -tetrahedrons.

Journal ArticleDOI
TL;DR: Semiconductor quantum dots and metal nanoparticles have extensive applications, e.g., in vitro and in vivo bioimaging, and toxic effects of NPs and their clearance from the body are discussed.
Abstract: We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide-zinc sulfide (CdSe-ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon of metal NPs, and their bioimaging applications. The PL properties of QDs are discussed with reference to their band gap structure and various electronic transitions, relations of PL and photoactivated PL with surface defects, and blinking of single QDs. Optical properties of Ag and Au NPs are discussed with reference to their size- and shape-dependent surface plasmon bands, electron dynamics and relaxation, and surface-enhanced Raman scattering (SERS). The bioimaging applications are discussed with reference to in vitro and in vivo imaging of live cells, and in vivo imaging of cancers, tumor vasculature, and lymph nodes. Other aspects of the review are in vivo deep tissue imaging, multiphoton excitation, NIR fluorescence and SERS imaging, and toxic effects of NPs and their clearance from the body.

Journal ArticleDOI
TL;DR: It is shown here that an R3-MYB protein, AtMYBL2, acts as a transcriptional repressor and negatively regulates the biosynthesis of anthocyanin in Arabidopsis.
Abstract: In Arabidopsis, MYB transcription factors regulate flavonoid biosynthesis via the formation of protein complexes with a basic helix-loop-helix (bHLH) transcription factor and a WD40 repeat protein. Several R3-type single-MYB proteins (R3-MYB), such as CPC and TRY, act as negative regulators of the development of epidermal cells. However, such regulators of flavonoid biosynthesis have not yet been reported, to our knowledge. We show here that an R3-MYB protein, AtMYBL2, acts as a transcriptional repressor and negatively regulates the biosynthesis of anthocyanin in Arabidopsis. In an AtMYBL2 knockout line (mybl2), the expression of the DFR and TT8 genes was enhanced and resulted in the ectopic accumulation of anthocyanin, while ectopic expression of AtMYBL2 or of a chimeric repressor that is a dominant negative form of AtMYBL2 suppressed the expression of DFR and TT8, and the biosynthesis of anthocyanin. The expression of AtMYBL2 was detected in various tissues but not in those in which anthocyanin accumulated or TT8 was expressed. The minimal repression domain of AtMYBL2 was found to be the six amino acids (TLLLFR) at the carboxyl terminus, and TLLLFR appears to be a novel repression motif that is different from the ERF-associated amphiphilic repression (EAR) motif. The defective phenotype of mybl2 mutants was complemented by 35S:AtMYBL2 but enhanced by a truncated form of AtMYBL2 from which the repression domain had been deleted. AtMYBL2 bound directly to TT8 protein and this complex suppressed the expression of DFR and TT8. The repression activity of AtMYBL2 appears to play a critical role in the regulation of anthocyanin biosynthesis.

Journal ArticleDOI
TL;DR: Antibiotics were removed more efficiently at Hong Kong STPs employing secondary treatment processes compared with those using primary treatment only and for NOR and TET, which are readily adsorbed to particulate matter, while lower removal efficiencies were observed for ERY-H(2)O, which is relatively persistent in the environment.

Journal ArticleDOI
TL;DR: The present results have shown that the cost effectiveness in the numerical basis sets implemented in the DFT code DMol3 is superior to that in Gaussian basis sets in terms of accuracy per computational cost.
Abstract: Binding energies of selected hydrogen bonded complexes have been calculated within the framework of density functional theory (DFT) method to discuss the efficiency of numerical basis sets implemented in the DFT code DMol3 in comparison with Gaussian basis sets. The corrections of basis set superposition error (BSSE) are evaluated by means of counterpoise method. Two kinds of different numerical basis sets in size are examined; the size of the one is comparable to Gaussian double zeta plus polarization function basis set (DNP), and that of the other is comparable to triple zeta plus double polarization functions basis set (TNDP). We have confirmed that the magnitudes of BSSE in these numerical basis sets are comparative to or smaller than those in Gaussian basis sets whose sizes are much larger than the corresponding numerical basis sets; the BSSE corrections in DNP are less than those in the Gaussian 6-311+G(3df,2pd) basis set, and those in TNDP are comparable to those in the substantially large scale Gaussian basis set aug-cc-pVTZ. The differences in counterpoise corrected binding energies between calculated using DNP and calculated using aug-cc-pVTZ are less than 9 kJ/mol for all of the complexes studied in the present work. The present results have shown that the cost effectiveness in the numerical basis sets in DMol3 is superior to that in Gaussian basis sets in terms of accuracy per computational cost.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that microwave signals with device-compatible output power levels can be generated from a single magnetic tunnel junction with a lateral size of 100nm, seven orders of magnitude smaller than conventional radio-frequency oscillators.
Abstract: Spin-momentum transfer between a spin-polarized current and a ferromagnetic layer can induce steady-state magnetization precession, and has recently been proposed as a working principle for ubiquitous radio-frequency devices for radar and telecommunication applications. However, so far, the development of industrially attractive prototypes has been hampered by the inability to identify systems that can provide enough power. Here, we demonstrate that microwave signals with device-compatible output power levels can be generated from a single magnetic tunnel junction with a lateral size of 100 nm, seven orders of magnitude smaller than conventional radio-frequency oscillators. We find that in MgO magnetic tunnel junctions the perpendicular torque induced by the spin-polarized current on the local magnetization can reach 25% of the in-plane spin-torque term, although showing a different bias dependence. Both findings contrast with the results obtained on all-metallic structures, previously investigated, reflecting the fundamentally different transport mechanisms in the two types of structure. Improvements in the microwave output efficiency of MgO-based magnetic tunnel junctions brings them a step closer to practical applications and enables greater insight into the physics of spin transfer in such devices.

Journal ArticleDOI
TL;DR: A very simple but the most effective method for the direct deposition of Au clusters onto several kinds of PCPs including MOF-5 by solid grinding with a volatile organogold complex without using organic solvents is reported.
Abstract: Gold has turned out to be one of the most attractive elements in catalysis research since the discovery of CO oxidation at 70 8C over Au nanoparticles (NPs) supported on base metal oxides. During the last decade, Au NPs supported on metal oxides and activated carbons (AC) have been widely studied for liquid phase reactions. In liquid phase reactions, catalytic performance of Au particles is mainly defined by two major factors: i) the nature of supports and ii) the size of Au particles. In particular, the size of 2 nm appears to be a critical point, where the Au particles dramatically change their catalytic and physicochemical properties. However, the conventional deposition–precipitation method is not applicable to AC due to the acidic nature of AC. Mixing Au colloids with AC could hardly give Au clusters with a diameter smaller than 2 nm. A latest trend in the selection of supports is the use of organic polymers. Recently, some organic polymers were found to be effective to stabilize colloidal Au in a cluster size, which showed high catalytic activity for aerobic oxidation of alcohols at room temperature. However, a constraint is that sophisticated synthetic techniques are usually required to obtain Au clusters. On the other hand, porous coordination polymers (PCPs) consisting of metal ions and organic ligands with highly regular nanometer-sized cavities or channels are an emerging class of porous materials. They are expected to be efficient supports for metal clusters to control size and shape by means of their cavities. In addition, PCPs have a wide variety of porous structures, various kinds of components, and surface properties which would lead to tailor-made catalysts for the desired reactions. Thus, investigations of the preparation methods for PCP supported Au clusters and the support effect of PCPs would offer a new frontier in catalysis by Au. Fischer and co-workers have reported the preparation of Pd, Cu, Ru clusters, and Au NPs stabilized by Zncontaining PCP, MOF-5 ([Zn4O ACHTUNGTRENNUNG(bdc)3]n (bdc=benzene-1,4dicarboxylate) by chemical vapour deposition (CVD). Although Au particles could be hardly deposited in cluster size, they were obtained as NPs in the range of 5 to 20 nm on MOF-5 due to weak interaction. 12] Therefore, the generation of Au clusters that fit in and/or on the cavities of PCPs is still a challenging research target. Herein we report a very simple but the most effective method for the direct deposition of Au clusters onto several kinds of PCPs including MOF-5 by solid grinding with a volatile organogold complex without using organic solvents. We also investigated their catalytic properties for the liquid phase alcohol oxidation with molecular oxygen. To the best of our knowledge, catalysis of PCP supported Au clusters in liquid phase has not yet been studied. The PCP supports used were one-dimensionally channelled PCPs such as CPL-1 ([Cu2ACHTUNGTRENNUNG(pzdc)2 ACHTUNGTRENNUNG(pyz)]n, pzdc=pyrazine-2,3-dicarboxylate, pyz=pyrazine), CPL-2 ([Cu2ACHTUNGTRENNUNG(pzdc)2ACHTUNGTRENNUNG(bpy)]n, bpy=4,4’-bipyridine), [14] Al-MIL53 ([Al(OH) ACHTUNGTRENNUNG(bdc)]n) [15] with pores of 4 @6, 6 @ 8, 8.5 @8.5 A, respectively, and three-dimensional PCPs such as MOF-5 and Cu-BTC ([Cu3ACHTUNGTRENNUNG(btc)2]n (btc=benzene-1,3,5-tricarboxylate) [16] with pores of 15 @ 15 and 11 @11 A, respectively. Volatile organogold complex, Me2AuACHTUNGTRENNUNG(acac) (acac= acetylacetonate) and PCPs were ground in an agate mortar in air for 20 min at room temperature. Then the mixture was treated in a stream of 10 vol% H2 in N2 at 120 8C for 2 h to obtain Au/ [a] Dr. T. Ishida, M. Nagaoka, Prof. Dr. M. Haruta Department of Applied Chemistry Graduate School of Urban Environmental Sciences Tokyo Metropolitan University, 1-1 Minami-osawa Hachioji, Tokyo 192-0397 (Japan) Fax: (+81) 42-677-2851 E-mail : haruta-masatake@center.tmu.ac.jp [b] Dr. T. Ishida, Dr. T. Akita, Prof. Dr. M. Haruta Japan Science and Technology Agency (JST) CREST, 4-1-8 Hon-cho, Kawaguchi Saitama 322-0012 (Japan) [c] Dr. T. Akita Research Institute for Ubiquitous Energy Devices National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka Ikeda, Osaka 563-8577 (Japan) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200800980.

Journal ArticleDOI
TL;DR: In this article, the crystal structure of LnFeAsO$1-y$ (Ln = La, Nd) has been studied by the powder neutron diffraction technique.
Abstract: The crystal structure of LnFeAsO$_{1-y}$ (Ln = La, Nd) has been studied by the powder neutron diffraction technique. The superconducting phase diagram of NdFeAsO$_{1-y}$ is established as a function of oxygen content which is determined by Rietveld refinement. The small As-Fe bond length suggests that As and Fe atoms are connected covalently. FeAs$_4$-tetrahedrons transform toward a regular shape with increasing oxygen deficiency. Superconducting transition temperatures seem to attain maximum values for regular FeAs$_4$-tetrahedrons.

Journal ArticleDOI
TL;DR: The excellent catalytic activity of Fe nanoparticles with no protective shell for the hydrolytic dehydrogenation of aqueous AB under argon and even in air at room temperature is reported.
Abstract: Iron, the most ubiquitous of the transition metals and the fourth most plentiful element in the Earth s crust, has been studied intensively because of its very potent magnetic and catalytic properties. However, its reactivity with respect to water and oxygen, especially on a nanoscale, generally limits its applications to a non-oxidizing environment where water and oxygen are not present. Recent studies involving coating Fe nanoparticles with an outer shell have succeeded in minimizing their oxidation and agglomeration. However, the presence of protective shell around the Fe particles is unfavorable for catalytic applications, where surface Fe active sites are needed. It is therefore understandable that, to date, there has been no report on the catalytic application of Fe nanoparticles without any protective shell other than the solvent components in aqueous solution in air. Fe nanoparticles that exert their powerful catalytic ability in aqueous solution or even in air will therefore significantly benefit both academic research and practical applications of iron-based materials. The search for effective hydrogen-storage materials is one of the most difficult challenges as we move towards a hydrogen-powered society as a long-term solution to current energy problems. Ammonia borane (AB; NH3BH3) has a hydrogen content of 19.6 wt%, which exceeds that of gasoline and therefore makes it an attractive candidate for chemical hydrogen-storage applications. The development of efficient and economical catalysts to further improve the kinetic properties under moderate conditions is therefore important for the practical application of this system. Herein we report the excellent catalytic activity of Fe nanoparticles with no protective shell for the hydrolytic dehydrogenation of aqueous AB under argon and even in air at room temperature. The Fe nanoparticles were pre-synthesized by reduction of FeSO4 with NaBH4 and then AB was immediately added to the solution to be catalytically hydrolyzed (AB/FeSO4/NaBH4 1.0:0.12:0.16). The gas generated was identified by mass spectrometry and its amount was measured volumetrically. Although black Fe nanoparticles were obtained rapidly, the evolution of 134 mL of hydrogen took more than 160 min (Figure 1a). The molar ratio of hydrolytically generated H2 to

Journal ArticleDOI
TL;DR: In this article, the advantages of the aerosol deposition (AD) method are highlighted by realizing a comparison with conventional thin-film methods and thermal spray technology, and examples of integration of AD method in the fabrication of electronic components are also given to show the easiness in usage and in integration of this method in device process flow.
Abstract: Ceramic integration technology requires downsizing and/or improvement of device performance in many applications, such as in the fabrication of microelectromechanical systems, display devises, fuel cells, optical devices, and RF components. For these applications, realization of high-speed deposition rate, low process temperature, and fine patterning in ceramic coating are very important. The aerosol deposition (AD) method has many advantages for above requirements in comparison with conventional thin-film method or thermal spray coating technology. In this article, advantages of the AD method are highlighted by realizing a comparison with conventional thin-film methods and thermal spray technology. Challenges associated with AD method are also highlighted. At the end, examples of integration of AD method in the fabrication of electronic components are also given to show the easiness in usage and in integration of this method in the device process flow.

Journal ArticleDOI
TL;DR: In this paper, the reference model for proactive action (RMfPA) is proposed to develop and implement sustainable manufacturing (CSM) at both the macro-meso-field level and the international level.

Journal ArticleDOI
TL;DR: FANCJ-depleted cells treated with the G4-interactive compound telomestatin displayed impaired proliferation and elevated levels of apoptosis and DNA damage compared to small interfering RNA control cells, suggesting that G4 DNA is a physiological substrate of FANCJ.
Abstract: FANCJ mutations are associated with breast cancer and genetically linked to the bone marrow disease Fanconi anemia (FA). The genomic instability of FA-J mutant cells suggests that FANCJ helicase functions in the replicational stress response. A putative helicase with sequence similarity to FANCJ in Caenorhabditis elegans (DOG-1) and mouse (RTEL) is required for poly(G) tract maintenance, suggesting its involvement in the resolution of alternate DNA structures that impede replication. Under physiological conditions, guanine-rich sequences spontaneously assemble into four-stranded structures (G quadruplexes [G4]) that influence genomic stability. FANCJ unwound G4 DNA substrates in an ATPase-dependent manner. FANCJ G4 unwinding is specific since another superfamily 2 helicase, RECQ1, failed to unwind all G4 substrates tested under conditions in which the helicase unwound duplex DNA. Replication protein A stimulated FANCJ G4 unwinding, whereas the mismatch repair complex MSH2/MSH6 inhibited this activity. FANCJ-depleted cells treated with the G4-interactive compound telomestatin displayed impaired proliferation and elevated levels of apoptosis and DNA damage compared to small interfering RNA control cells, suggesting that G4 DNA is a physiological substrate of FANCJ. Although the FA pathway has been classically described in terms of interstrand cross-link (ICL) repair, the cellular defects associated with FANCJ mutation extend beyond the reduced ability to repair ICLs and involve other types of DNA structural roadblocks to replication.

Journal ArticleDOI
08 Aug 2008-Science
TL;DR: This Perspective focuses on the use of classical molecular dynamics and so-called coarse-grain models to explore phenomena involving self-assembly in complex fluids and biological systems.
Abstract: Relentless increases in the size and performance of multiprocessor computers, coupled with new algorithms and methods, have led to novel applications of simulations across chemistry. This Perspective focuses on the use of classical molecular dynamics and so-called coarse-grain models to explore phenomena involving self-assembly in complex fluids and biological systems.


Journal ArticleDOI
TL;DR: This work presents a multi-terminal device with a Au Hall cross and an FePt perpendicular spin injector to detect giant direct and inverse SHEs at room temperature, enabling the unambiguous identification of SHEs.
Abstract: Conversion of charge current into pure spin current and vice versa in non-magnetic semiconductors or metals, which are called the direct and inverse spin Hall effects (SHEs), provide a new functionality of materials for future spin-electronic architectures. Thus, the realization of a large SHE in a device with a simple and practical geometry is a crucial issue for its applications. Here, we present a multi-terminal device with a Au Hall cross and an FePt perpendicular spin injector to detect giant direct and inverse SHEs at room temperature. Perpendicularly magnetized FePt injects or detects perpendicularly polarized spin current without magnetic field, enabling the unambiguous identification of SHEs. The unprecedentedly large spin Hall resistance of up to 2.9 mOmega is attributed to the large spin Hall angle in Au through the skew scattering mechanism and the highly efficient spin injection due to the well-matched spin resistances of the chosen materials.

Journal ArticleDOI
TL;DR: It is suggested that betaKlotho expression is a crucial determinant of the FGF21 specificity of the target cells upon which it acts in an endocrine fashion.
Abstract: Fibroblast growth factor (FGF) 21, a structural relative of FGF23 that regulates phosphate homeostasis, is a regulator of insulin-independent glucose transport in adipocytes and plays a role in the regulation of body weight. It also regulates ketogenesis and adaptive responses to starvation. We report that in a reconstituted receptor activation assay system using BaF3 cells, which do not endogenously express any type of FGF receptor (FGFR) or heparan sulfate proteoglycan, FGF21 alone does not activate FGFRs and that βKlotho is required for FGF21 to activate two specific FGFR subtypes: FGFR1c and FGFR3c. Coexpression of βKlotho and FGFR1c on BaF3 cells enabled FGF21, but not FGF23, to activate receptor signaling. Conversely, coexpression of FGFR1c and Klotho, a protein related to βKlotho, enabled FGF23 but not FGF21 to activate receptor signaling, indicating that expression of βKlotho/Klotho confers target cell specificity on FGF21/FGF23. In all of these cases, heparin enhanced the activation but was not e...

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TL;DR: In this article, the authors reviewed the recent approaches in realizing carrier-transport-enhanced CMOS, and the critical issues, fabrication techniques, and device performance of MOSFETs using three types of channel materials, Si (SiGe) with uniaxial strain, Ge-on-insulator (GOI), and III-V semiconductors, are presented.
Abstract: An effective way to reduce supply voltage and resulting power consumption without losing the circuit performance of CMOS is to use CMOS structures using high carrier mobility/velocity. In this paper, our recent approaches in realizing these carrier-transport-enhanced CMOS will be reviewed. First, the basic concept on the choice of channels for increasing on current of MOSFETs, the effective-mass engineering, is introduced from the viewpoint of both carrier velocity and surface carrier concentration under a given gate voltage. Based on this understanding, critical issues, fabrication techniques, and the device performance of MOSFETs using three types of channel materials, Si (SiGe) with uniaxial strain, Ge-on-insulator (GOI), and III-V semiconductors, are presented. As for the strained devices, the importance of uniaxial strain, as well as the combination with multigate structures, is addressed. A novel subband engineering for electrons on (110) surfaces is also introduced. As for GOI MOSFETs, the versatility of the Ge condensation technique for fabricating a variety of Ge-based devices is emphasized. In addition, as for III-V semiconductor MOSFETs, advantages and disadvantages on low effective mass are examined through simple theoretical calculations.

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TL;DR: It is argued that the large SHE observed experimentally in platinum is of intrinsic nature and that the vertex correction due to impurity scattering vanishes.
Abstract: Spin Hall effect (SHE) is studied with first-principles relativistic band calculations for platinum, which is one of the most important materials for metallic SHE and spintronics. We find that intrinsic spin Hall conductivity (SHC) is as large as $\ensuremath{\sim}2000(\ensuremath{\hbar}/e)(\ensuremath{\Omega}\text{ }\mathrm{cm}{)}^{\ensuremath{-}1}$ at low temperature and decreases down to $\ensuremath{\sim}200(\ensuremath{\hbar}/e)(\ensuremath{\Omega}\text{ }\mathrm{cm}{)}^{\ensuremath{-}1}$ at room temperature. It is due to the resonant contribution from the spin-orbit splitting of the doubly degenerated $d$ bands at high-symmetry $L$ and $X$ points near the Fermi level. By modeling these near degeneracies by an effective Hamiltonian, we show that SHC has a peak near the Fermi energy and that the vertex correction due to impurity scattering vanishes. We therefore argue that the large SHE observed experimentally in platinum is of intrinsic nature.