Showing papers by "National Institute of Advanced Industrial Science and Technology published in 2004"
TL;DR: A giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs is reported, indicating that coherency of wave functions is conserved across the tunnel barrier.
Abstract: The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs)1,2 is the key to developing magnetoresistive random-access-memory (MRAM), magnetic sensors and novel programmable logic devices3,4,5. Conventional MTJs with an amorphous aluminium oxide tunnel barrier, which have been extensively studied for device applications, exhibit a magnetoresistance ratio up to 70% at room temperature6. This low magnetoresistance seriously limits the feasibility of spintronics devices. Here, we report a giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs. The origin of this enormous TMR effect is coherent spin-polarized tunnelling, where the symmetry of electron wave functions plays an important role. Moreover, we observed that their tunnel magnetoresistance oscillates as a function of tunnel barrier thickness, indicating that coherency of wave functions is conserved across the tunnel barrier. The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing gigabit-scale MRAM.
2,956 citations
TL;DR: Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. S. Nagar, Punjab-160 062, India, Institute of Biochemistry, Faculty of Medicine, Polytechnic University, Via Ranieri 67, IT-60100 Ancona, Italy, and Department of Medicinal Chemistry & Natural Products,The Hebrew University of Jerusalem, School of Pharmacy-Faculty of medicine, Jerusalem 91120, Israel.
Abstract: Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar,Mohali, Punjab-160 062, India, Institute of Biochemistry, Faculty of Medicine, Polytechnic University, Via Ranieri 67, IT-60100 Ancona, Italy,Green Biotechnology Research Group, The Special Division for Human Life Technology, National Institute of Advanced Industrial Science andTechnology, 1-8-31 Midorigaoka, Ikeda, Osaka-563-8577, Japan, and Department of Medicinal Chemistry & Natural Products,The Hebrew University of Jerusalem, School of Pharmacy-Faculty of Medicine, Jerusalem 91120, IsraelReceived March 2, 2004
2,570 citations
TL;DR: In this article, the authors demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water.
Abstract: We demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water. Water-stimulated enhanced catalytic activity results in massive growth of superdense and vertically aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotube material with carbon purity above 99.98%. Moreover, patterned, highly organized intrinsic nanotube structures were successfully fabricated. The water-assisted synthesis method addresses many critical problems that currently plague carbon nanotube synthesis.
2,405 citations
TL;DR: Observations in situ of defect formation in single graphene layers by high-resolution TEM are reported and are expected to be of use when engineering the properties of carbon nanostructures for specific device applications.
Abstract: Atomic-scale defects in graphene layers alter the physical and chemical properties of carbon nanostructures. Theoretical predictions have recently shown that energetic particles such as electrons and ions can induce polymorphic atomic defects in graphene layers as a result of knock-on atom displacements. However, the number of experimental reports on these defects is limited. The graphite network in single-walled carbon nanotubes has been visualized by transmission electron microscopy (TEM) and their chiral indices have been determined. But the methods used require a long image acquisition time and intensive numerical treatments after observations to find an 'average' image, which prevents the accurate detection and investigation of defect structures. Here we report observations in situ of defect formation in single graphene layers by high-resolution TEM. The observed structures are expected to be of use when engineering the properties of carbon nanostructures for specific device applications.
1,517 citations
TL;DR: In this article, room-temperature ionic liquids (RTILs) based on 1-butyl-3-methylimidazolium ([bmim]) with a variety of fluorinated anions were prepared, and the thermal behavior, density, viscosity, self-diffusion coefficients of the cations and anions, and ionic conductivity were measured over a wide temperature range.
Abstract: Room-temperature ionic liquids (RTILs) based on 1-butyl-3-methylimidazolium ([bmim]) with a variety of fluorinated anions were prepared, and the thermal behavior, density, viscosity, self-diffusion coefficients of the cations and anions, and ionic conductivity were measured over a wide temperature range. The temperature dependencies of the self-diffusion coefficient, viscosity, ionic conductivity, and molar conductivity have been fitted to the Vogel−Fulcher−Tamman equation, and the best-fit parameters for the self-diffusion coefficient, viscosity, ionic conductivity, and molar conductivity have been estimated, together with the linear fitting parameters for the density. The self-diffusion coefficients determined for the individual ions by pulsed-field-gradient spin−echo NMR method exhibit higher values for the cation compared with the anion over a wide temperature range, even if its radius is larger than that of the anionic radii. The summation of the cationic and anionic diffusion coefficients for the RT...
1,345 citations
TL;DR: It is demonstrated that, different from the current consensus, Ge2Sb2Te5, the material of choice in DVD-RAM, does not possess the rocksalt structure but more likely consists of well-defined rigid building blocks that are randomly oriented in space consistent with cubic symmetry.
Abstract: Present-day multimedia strongly rely on rewritable phase-change optical memories. We demonstrate that, different from the current consensus, Ge(2)Sb(2)Te(5), the material of choice in DVD-RAM, does not possess the rocksalt structure but more likely consists of well-defined rigid building blocks that are randomly oriented in space consistent with cubic symmetry. Laser-induced amorphization results in drastic shortening of covalent bonds and a decrease in the mean-square relative displacement, demonstrating a substantial increase in the degree of short-range ordering, in sharp contrast to the amorphization of typical covalently bonded solids. This novel order-disorder transition is due to an umbrella-flip of Ge atoms from an octahedral position into a tetrahedral position without rupture of strong covalent bonds. It is this unique two-state nature of the transformation that ensures fast DVD performance and repeatable switching over ten million cycles.
1,140 citations
George Washington University1, Colgate University2, St. John's University3, University of Wisconsin-Madison4, Swedish Museum of Natural History5, University of Göttingen6, National Institute of Advanced Industrial Science and Technology7, University of Mainz8, University of Lausanne9, Open University10, University of Edinburgh11, Utrecht University12, University of Tasmania13, University of Maryland, College Park14, Hiroshima University15, University of Tübingen16, University of Saskatchewan17, University of Science and Technology of China18
TL;DR: In this article, the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometer (LA-ICP-MS), secondary ion mass spectrometry (SIMS), and laser fluorination analyses, were reported.
Abstract: This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.
1,131 citations
TL;DR: In this article, a dye-sensitized solar cell with six different structures, with layers of nanoparticles, light-scattering particles, and mixture of nanoparticle and light scattering particles on the conducting glass at a desirable sequence and thickness, were designed and investigated.
1,044 citations
TL;DR: A new high-resolution structure is reported for bovine rhodopsin, the visual pigment in rod photoreceptor cells, and a theoretical study of the chromophore geometry has been carried out using combined quantum mechanics/force field molecular dynamics.
1,035 citations
TL;DR: Martensitic and magnetic transformations of the Heusler Ni50Mn50−yXy (X=In, Sn and Sb) alloys were investigated by differential scanning calorimetry measurement and the vibrating sample magnetometry technique.
Abstract: Martensitic and magnetic transformations of the Heusler Ni50Mn50−yXy (X=In, Sn and Sb) alloys were investigated by differential scanning calorimetry measurement and the vibrating sample magnetometry technique. In all these alloy systems, the austenite phase with the ferromagnetic state was transformed into the martensite phase, which means that these Heusler alloys have potential as Ga-free ferromagnetic shape memory alloys (FSMAs). Furthermore, multiple martensitic transformations, such as two- or three-step martensitic transformations, occur in all these alloy systems. It was confirmed by transmission electron microscopy observation that the crystal structure of the martensite phase is an orthorhombic four-layered structure which has not been reported in other FSMAs. Therefore, the present Ga-free FSMAs have the great possibility of the appearance of a large magnetic-field-induced strain.
968 citations
TL;DR: In this article, an efficient simulation approach under constant external stress and temperature, modifying Parrinello-Rahman (PR) method using useful sampling techniques developed recently, such as massive Nos\'e-Hoover chain method and hybrid Monte Carlo method, was proposed.
Abstract: Molecular simulations, when they are used to understand properties characterizing the mechanical strength of solid materials, such as stress-strain relation or Born stability criterion, by using elastic constants, are sometimes seriously time consuming. In order to resolve this problem, we propose an efficient simulation approach under constant external stress and temperature, modifying Parrinello-Rahman (PR) method using useful sampling techniques developed recently---massive Nos\'e-Hoover chain method and hybrid Monte Carlo method. Test calculations on the Ni crystal employing the embedded atom method have shown that our method greatly improved the efficiency in sampling the elastic properties compared with the conventional PR method.
TL;DR: There seems to be a slight bias against GC-rich transcripts in current gene prediction procedures in the “full-length long Japan” collection of sequenced human cDNAs.
Abstract: As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.
TL;DR: This family of molecularly engineered graphite with a one-dimensional tubular shape and a chemically accessible surface constitutes an important step toward molecular electronics.
Abstract: An amphiphilic hexa-peri-hexabenzocoronene self-assembles to form a π-electronic, discrete nanotubular object. The object is characterized by an aspect ratio greater than 1000 and has a uniform, 14-nanometer-wide, open-ended hollow space, which is an order of magnitude larger than those of carbon nanotubes. The wall is 3 nanometers thick and consists of helical arrays of the π-stacked graphene molecule, whose exterior and interior surfaces are covered by hydrophilic triethylene glycol chains. The graphitic nanotube is redox active, and a single piece of the nanotube across 180-nanometer-gap electrodes shows, upon oxidation, an electrical conductivity of 2.5 megohms at 285 kelvin. This family of molecularly engineered graphite with a one-dimensional tubular shape and a chemically accessible surface constitutes an important step toward molecular electronics.
TL;DR: This article presented a new keyword extraction algorithm that applies to a single document without using a corpus and showed comparable performance to tfidf without using TFIDF without using any corpus, but the degree of biases of distribution is measured by the χ 2 -measure.
Abstract: We present a new keyword extraction algorithm that applies to a single document without using a corpus. Frequent terms are extracted first, then a set of cooccurrence between each term and the frequent terms, i.e., occurrences in the same sentences, is generated. Co-occurrence distribution shows importance of a term in the documentas follows. If probability distribution of co-occurrence between term a and the frequent terms is biased to a particular subset of frequent terms, then term a is likely to be a keyword. The degree of biases of distribution is measured by the χ 2 -measure. Our algorithm shows comparable performance to tfidf without using a corpus.
TL;DR: The semiclassical equation of motion for the wave packet of light is derived taking into account the Berry curvature in momentum-space, which leads to the shift of wave-packet motion perpendicular to the gradient of the dielectric constant, i.e., the polarization-dependent Hall effect of light.
Abstract: We derive the semiclassical equation of motion for the wave packet of light taking into account the Berry curvature in momentum-space. This equation naturally describes the interplay between orbital and spin angular momenta, i.e., the conservation of the total angular momentum of light. This leads to the shift of wave-packet motion perpendicular to the gradient of the dielectric constant, i.e., the polarization-dependent Hall effect of light. An enhancement of this effect in photonic crystals is also proposed.
TL;DR: Results indicate that RD26 functions as a transcriptional activator in ABA-inducible gene expression under abiotic stress in plants.
Abstract: *Summary Arabidopsis thaliana RD26 cDNA, isolated from dehydrated plants, encodes a NAC protein. Expression of the RD26 gene was induced not only by drought but also by abscisic acid (ABA) and high salinity. The RD26 protein is localized in the nucleus and its C terminal has transcriptional activity. Transgenic plants overexpressing RD26 were highly sensitive to ABA, while RD26-repressed plants were insensitive. The results of microarray analysis showed that ABA- and stress-inducible genes are upregulated in the RD26-overexpressed plants and repressed in the RD26-repressed plants. Furthermore, RD26 activated a promoter of its target gene in Arabidopsis protoplasts. These results indicate that RD26 functions as a transcriptional activator in ABAinducible gene expression under abiotic stress in plants.
TL;DR: Au catalysts have been used for deodorizers in rest rooms in Japan and will find growing applications in indoor air quality control, pollutant emission control, production of hydrogen energy carrier, and innovations in chemical processes as discussed by the authors.
Abstract: Gold can be deposited as nanoparticles on a variety of support materials by coprecipitation or deposition-precipitation of Au(OH)3, grafting of organo-gold complexes such as dimethyl-Au(III)-acetylacetonate, mixing of colloidal Au particles, and vacuum deposition. Owing to the moderate adsorption of at least one of reactants (for example, CO) on the edges and corners of Au nanoparticles and to the activation of the counter reactant (for example, O2) at the perimeter interface with the supports, supported Au nanoparticle catalysts exhibit unique and practically useful catalytic properties at relatively low temperature below 473K. They have already been commercially used for deodorizers in rest rooms in Japan and will find growing applications in indoor air quality control, pollutant emission control, production of hydrogen energy carrier, and innovations in chemical processes. Cluster science of Au may also open an exciting area of research showing some magic numbers for dramatic changes in reactivity.
TL;DR: In this article, a systematic study for numerical atomic basis orbitals ranging from H to Kr is presented, which can be used in large scale electronic structure calculations based on density functional theories (DFT).
Abstract: We present a systematic study for numerical atomic basis orbitals ranging from H to Kr, which could be used in large scale $\mathrm{O}(N)$ electronic structure calculations based on density-functional theories (DFT). The comprehensive investigation of convergence properties with respect to our primitive basis orbitals provides a practical guideline in an optimum choice of basis sets for each element, which well balances the computational efficiency and accuracy. Moreover, starting from the primitive basis orbitals, a simple and practical method for variationally optimizing basis orbitals is presented based on the force theorem, which enables us to maximize both the computational efficiency and accuracy. The optimized orbitals well reproduce convergent results calculated by a larger number of primitive orbitals. As illustrations of the orbital optimization, we demonstrate two examples: the geometry optimization coupled with the orbital optimization of a ${\mathrm{C}}_{60}$ molecule and the preorbital optimization for a specific group such as proteins. They clearly show that the optimized orbitals significantly reduce the computational efforts, while keeping a high degree of accuracy, thus indicating that the optimized orbitals are quite suitable for large scale DFT calculations.
TL;DR: The modifications discussed here include chitosan attached to sugars, dendrimers, cyclodextrins, crown ethers, and glass beads, which are excellent candidates for drug delivery systems or cell culture owing to their specificity.
TL;DR: In this article, a review describes the historical development, current status, and future prospects for nonthermal plasma (NTP) technology and its application as an air-pollution control.
Abstract: Summary: This review describes the historical development, current status, and future prospects for nonthermal plasma (NTP) technology and its application as an air-pollution control. In particular, this review focuses on the cutting-edge technology of hybrid NTP, where it is combined with other methods such as wet processing, the use of adsorbents, and catalysis. Historical landmarks in the development of NTP technology and the current status of large-scale applications are discussed. The general characteristics of the combined system of NTP with catalysts are described in the context of the decomposition of NOx and benzene.
Comparison of different NTP reactors for 200 ppm benzene decomposition (water vapor 0.5 vol.-%).
TL;DR: An initial model for RRAM is introduced with the assumption that the semiconducting part has a nonpercolating domain structure and it captures three key features observed in experiments: multilevel switchability of the resistance, its memory retention, and hysteretic behavior in the current-voltage curve.
Abstract: There is a current upsurge in research on nonvolatile two-terminal resistance random access memory (RRAM) for next generation electronic applications. The RRAM is composed of a simple sandwich of a semiconductor with two metal electrodes. We introduce here an initial model for RRAM with the assumption that the semiconducting part has a nonpercolating domain structure. We solve the model using numerical simulations and the basic carrier transfer mechanism is unveiled in detail. Our model captures three key features observed in experiments: multilevel switchability of the resistance, its memory retention, and hysteretic behavior in the current-voltage curve.
TL;DR: In this article, the Coulomb interaction was calculated from first principles, using the random-phase approximation, and an expression for the frequency-dependent Coulomb interactions was derived for the case of nickel.
Abstract: We propose a systematic procedure for constructing effective models of strongly correlated materials. The parameters, in particular the on-site screened Coulomb interaction $U$, are calculated from first principles, using the random-phase approximation. We derive an expression for the frequency-dependent $U(\ensuremath{\omega})$ and show, for the case of nickel, that its high-frequency part has significant influence on the spectral functions. We propose a scheme for taking into account the energy dependence of $U(\ensuremath{\omega})$, so that a model with an energy-independent local interaction can still be used for low-energy properties.
TL;DR: In this paper, the efficiency of electron injection from excited N3 dye (cis-bis-(4,4‘)-dicarboxy-2,2‘-bipyridine) dithiocyanato ruthenium(II), Ru(dcbpy)2 (NCS)2), into various nanocrystalline semiconductor (ZrO2, TiO2 and ZnO, ZnNO, Nb2O5, SnO2 or In2O3) films was studied by
Abstract: The efficiency of electron injection from excited N3 dye (cis-bis-(4,4‘-dicarboxy-2,2‘-bipyridine) dithiocyanato ruthenium(II), Ru(dcbpy)2 (NCS)2), into various nanocrystalline semiconductor (ZrO2, TiO2, ZnO, Nb2O5, SnO2, In2O3) films was studied by transient absorption spectroscopy. For TiO2, ZnO, Nb2O5, SnO2, or In2O3 films, injection efficiencies were found to be very high; for ZrO2 film, the efficiency was very low. These findings indicate that electron injection occurs efficiently if the LUMO level of N3 dye is located sufficiently far above the bottom of the conduction band of the semiconductor film. On the basis of the results, we discuss the reason TiO2 exhibits higher solar cell performance than other materials.
TL;DR: In North America and Europe, the pea aphid encompasses ecologically and genetically distinct host races, offering a model system for studies on sympatric speciation.
Abstract: In North America and Europe, the pea aphid ( Acyrthosiphon pisum ) encompasses ecologically and genetically distinct host races, offering a model system for studies on sympatric speciation ([ 1 ][1], [ 2 ][2]). One host race lives on red clover ( Trifolium pratense ) and cannot produce offspring on
University of Otago1, National Institute of Water and Atmospheric Research2, Fisheries and Oceans Canada3, National Institute for Environmental Studies4, University of Tokyo5, Memorial University of Newfoundland6, University of British Columbia7, Hong Kong University of Science and Technology8, Bowling Green State University9, National Institute of Advanced Industrial Science and Technology10, Hokkaido University11, Dalhousie University12, Central Research Institute of Electric Power Industry13, University of Victoria14
TL;DR: The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
Abstract: Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
TL;DR: It is quantitatively determined that the biological functions of horizontally transferred genes, except mobile element genes, are biased to three categories: cell surface, DNA binding and pathogenicity-related functions, so the transferability of genes seems to depend heavily on their functions.
Abstract: Horizontal gene transfer is one of the main mechanisms contributing to microbial genome diversification. To clarify the overall picture of interspecific gene flow among prokaryotes, we developed a new method for detecting horizontally transferred genes and their possible donors by Bayesian inference with training models for nucleotide composition. Our method gives the average posterior probability (horizontal transfer index) for each gene sequence, with a low horizontal transfer index indicating recent horizontal transfer. We found that 14% of open reading frames in 116 prokaryotic complete genomes were subjected to recent horizontal transfer. Based on this data set, we quantitatively determined that the biological functions of horizontally transferred genes, except mobile element genes, are biased to three categories: cell surface, DNA binding and pathogenicity-related functions. Thus, the transferability of genes seems to depend heavily on their functions.
TL;DR: In marked contrast to the beneficial effect of regular aerobic exercise, several months of resistance training “reduces” central arterial compliance in healthy men.
Abstract: Background— Reductions in the compliance of central arteries exert a number of adverse effects on cardiovascular function and disease risk. Endurance training is efficacious in increasing arterial compliance in healthy adults. We determined the effects of resistance training on carotid arterial compliance using the intervention study design. Methods and Results— Twenty-eight healthy men 20 to 38 years old were randomly assigned to the intervention group (n=14) and the control group (n=14). Control subjects were instructed not to alter their normal activity levels throughout the study period. Intervention subjects underwent 3 supervised resistance training sessions per week for 4 months and detraining for a subsequent 4 months. The resistance training increased maximal strength in all muscle groups tested (P<0.001). There were no significant differences in baseline arterial compliance and β-stiffness index between the intervention and control groups. In the intervention group, carotid arterial compliance d...