Showing papers by "National Institute of Advanced Industrial Science and Technology published in 1998"

A novel mode of DNA recognition by a beta-sheet revealed by the solution structure of the GCC-box binding domain in complex with DNA.

Abstract: The 3D solution structure of the GCC-box binding domain of a protein from Arabidopsis thaliana in complex with its target DNA fragment has been determined by heteronuclear multidimensional NMR in combination with simulated annealing and restrained molecular dynamic calculation. The domain consists of a three-stranded anti-parallel beta-sheet and an alpha-helix packed approximately parallel to the beta-sheet. Arginine and tryptophan residues in the beta-sheet are identified to contact eight of the nine consecutive base pairs in the major groove, and at the same time bind to the sugar phosphate backbones. The target DNA bends slightly at the central CG step, thereby allowing the DNA to follow the curvature of the beta-sheet.

Differences in Perception of Everyday Odors: a Japanese-German Cross-cultural Study

Abstract: There is a growing appreciation that experience with odors may strongly influence their perception. To further investigate this, the responses of 40 Japanese and 44 age-matched German women to everyday odorants were compared. Subjects were presented with 18 stimuli in squeeze bottles and asked to rate them according to intensity, familiarity, pleasantness and edibility, to describe associations elicited by them and, if possible, to name them. One-third of the odorants were presumed to be familiar to the Japanese only, one-third to the Germans and one-third to both populations. Significant differences were found between the two populations on all measures. Better performance by the Japanese in providing appropriate descriptors for 'Japanese' odorants and by the Germans for 'European' odorants supported the pre-selection of stimuli as culture-typical. Particularly clear differences between the two populations were found in pleasantness ratings. In general, a positive relationship was found between pleasantness and judgement of stimuli as edible, suggesting that culture-specific experiences-particularly of foods-may significantly influence odor perception. Somewhat unexpectedly, significant differences were also found between the two populations in intensity ratings for some odorants. These differences did not seem simply to be artefacts of the test situation and raise the possibility that experience may even influence such basic aspects of odor perception as stimulus intensity.

A 3-D self-reconfigurable structure

Abstract: A three-dimensional, self-reconfigurable structure is proposed. The structure is a fully distributed system composed of many identical 3-D units. Each unit has functions of changing local connection, information processing, and communication among neighborhood units. Groups of units cooperate to change their connection so that the shape of the whole solid structure transforms into an arbitrary shape. Also, the structure can repair itself by rejecting faulty units, replacing them with spare units. This kind of self-maintainability is essential to structure's longevity in hazardous or remote environments such as space or deep sea where human operators cannot approach. We have designed and built a prototype unit to examine the feasibility of the 3-D self-reconfigurable concept. The design of the unit, method of reconfiguration, hardware implementation, and results of preliminary experiments are shown. In the last part of the paper, distributed software for self-reconfiguration is discussed.

High Resolution X-ray Photoelectron Spectroscopy Measurements of Octadecanethiol Self-Assembled Monolayers on Au(111)

Abstract: We have measured high-resolution X-ray photoelectron spectroscopy (XPS) spectra of 1-octadecanethiol (ODT) self-assembled monolayers (SAMs) on a Au(111) surface in order to investigate the Au−S binding properties at the initial stage of SAM growth and after the desorption of the ODT from the Au surface. For the SAM prepared by the 1 min immersion into the ODT solution, we found new sulfur species around 161 eV and assigned it to isolated sulfur without C−S cleavage. We also confirmed the presence of a similar 161 eV peak in the S(2p) spectra after desorption of the ODT molecules. Furthermore, we observed a peak shift in the carbon 1s (C(1s)) peak, depending on the surface coverage of the ODT. In addition to the C(1s) peak of 285.1 eV which might correspond to alkyl chains of densely packed ODT molecules, another lower binding energy peak at 284.3 eV appeared after annealing. This lower C(1s) binding energy peak formation suggested that some of the alkyl chains for the remaining ODT molecules might be orie...

Effect of calcination temperature on the catalytic activity of Au colloids mechanically mixed with TiO2 powder for CO oxidation

Abstract: In order to elucidate the role of the contact structure between gold and metal oxide support in low-temperature CO oxidation, a mechanical mixture of colloidal gold with TiO2 powder was prepared and calcined at different temperatures. The sample calcined at 473 K, which is composed of spherical gold particles with a mean diameter of 5.1 nm and TiO2 powder, is poorly active for CO oxidation at temperatures up to 473 K. The catalytic activity appreciably increases with an increase in calcination temperature up to 873 K even though gold particles grow to larger ones, reaching a level with almost the same turnover frequency as that of Au/TiO2 prepared by a deposition–precipitation method.

Selective oxidation of propylene over gold deposited on titanium-based oxides

Abstract: Gold supported on titanium-based metal oxides can assist the selective partial oxidation of propylene at temperatures from 313 K to 573 K in a gas containing both H2 and O2 The preparation method was found to be crucial in controlling the selectivities In general, impregnation and chemical vapor deposition methods do not produce selective catalysts Only the deposition-precipitation method makes gold selective to propylene oxide or propanal, suggesting that a strong contact between the gold particles and the titanium ion sites on the support is important The effect of changing the support was also dramatic; the use of the anatase form of TiO2 and Ti-MCM-41 results in propylene oxide production, while the rutile structure of TiO2 caused complete oxidation to CO2 Microporous crystalline titanium silicates such as TS-1, TS-2, and Ti-β zeolite make gold relatively selective to propanal and of the three TS-1 gives the highest selectivity These results indicate that the oxidation of propylene in the copresence of H2 must involve the surface of the supports and that the reaction takes place at the interface perimeter around the gold particles

Cytocompatibility of various metal and development of new titanium alloys for medical implants

Abstract: The cytocompatibility of new Ti alloys not containing Al and V such as Ti-15%Zr-4%Nb-4% Ta-0.2%Pd-0.05%N-0.2%O and Ti-15%Sn-4%Nb-2%Ta-0.2%Pd-0.2%O were investigated by comparing with those of pure Ti grade 2 and Ti-6%>Al-4%V ELI (Extra Low Interstitial) alloys. The relative growth ratio for the medium extraction of Al containing very little V ions (less than 0.02 mass ppm) was too low as compared to that of V free Al extraction. However, mixed powder extraction such as Ti + Zr + Nb + Ta and Ti + Sn + Nb + Ta exhibited evidently no effect on the relative growth ratio of L929 cells. The relative growth ratios of both L929 and MC3T3-El cells for the new Ti alloys were almost equal to 1 and were slightly higher than pure Ti grade 2 and Ti-6%Al-4%V ELI alloys. Also, the influence of extracting with Eagle's minimum essential medium (MEM) solution for L929 cells and ultra pure water for MC3T3-El cells on the relative growth ratio of cells were examined. Further, wear tests were conducted with the new Ti alloys, pure Ti grade 2 and Ti-6%nAl-4%V ELI alloy disks against apatite ceramics and alloy pins in Eagle's MEM solution. The relative growth ratios of L929 and MC3T3-E1 cells were estimated with these wear test solutions. The relative growth ratio of L929 cells were almost equal to 1 for the new Ti alloys and pure Ti grade 2 against apatite ceramics pin up to 10 5 cycles. However, the relative growth ratios of L929 and MC3T3-E1 cells sharply decreased for Ti-6%Al-4%V ELI disk against apatite ceramics pin from 3 x 10 4 wear cycles. It was observed that the pH of the Eagle's MEM solution gradually increased as the number of wear cycles increased in all the cases of alloy disk against apatite ceramics pin. Also, the V ion concentration increased as the number of wear cycles increased. This result was also similar for MC3T3-El cells. Further, the relationship between metallic concentration in the medium extracted with Ti, Al, V, Zr, Sn, Nb, Ta, and Pd powders and the relative growth ratios of L929 and MC3T3-E1 cells were evaluated. A similar dependence of the concentration of vanadium ion and the relative growth ratios of L929 and MC3T3-E1 cells were seen as in the case of the wear tests.

Active Sites Imaging for Oxygen Reduction at the La0.9Sr0.1MnO3 − x /Yttria‐Stabilized Zirconia Interface by Secondary‐Ion Mass Spectrometry

Abstract: Active sites for oxygen reduction were investigated at the interface of O{sub 2}/La{sub 0.9}Sr{sub 0.1}MnO{sub 3{minus}x} (LSM)/yttria-stabilized zirconia (YSZ). Isotopic oxygen ({sup 16}O/{sup 18}O) exchange under cathodic polarization and secondary-ion mass spectrometry (SIMS) analysis were examined to visualize the oxygen reduction active sites. The LSM mesh pattern electrode was prepared to define the contact area of LSM/YSZ. Under cathodic polarization, oxygen can diffuse through the dense LSM via oxygen vacancy, which promotes the electrode reaction. By SIMS imaging technique, the active sites for oxygen reduction were clearly determined as spots around the O{sub 2}/LSM/YSZ three-phase boundary. The line analysis of the SIMS image enabled the authors to draw a contour map of the {sup 18}O concentration in the cross section of YSZ. The diffusion paths were clearly visualized in the contour map. The width of the active sites for oxygen reduction is estimated to be less than 1 {micro}m under the examined condition.

Band gap energies of bulk, thin-film, and epitaxial layers of CuInSe2 and CuGaSe2

Abstract: Band gap and excitonic resonance energies of high-quality bulk single crystals, polycrystalline thin films, and epitaxial layers of CuInSe2 and CuGaSe2 were determined as a function of temperature by means of photoreflectance, optical absorption (OA), and photoluminescence measurements. OA spectra were fit including excitonic absorption from low temperature up to room temperature (RT). The band gap energy of 1.032 eV and free exciton (FE) resonance energy of 1.024 eV were obtained at RT for strain-free CuInSe2 giving an exciton binding energy of 7.5 meV. The band gap energy of both CuInSe2 and CuGaSe2 was found to be essentially independent of the molar ratio of Cu to group-III atom (Cu/III) for near-stoichiometric and Cu-rich samples. The disappearance of the FE absorption in the In-rich (Cu/In<0.88) CuInSe2 thin films was explained by plasma screening of Coulomb interactions. A slight decrease in the band gap energy of the In-rich films was attributed to a degradation of film quality such as high-density defects, grains, and structural disordering. The fundamental band gap energy in strained CuInSe2 and CuGaSe2 epilayers was shown to decrease due to in-plane biaxial tensile strain.

R&D activities in Japan on methanol synthesis from CO 2 and H 2

Abstract: Methanol synthesis from CO2 and H2 can be a useful process for conversion and transportation of hydrogen energy derived from non-fossil energies. More than ten research groups in Japan have extensively investigated the methanol synthesis from both academic and practical points of view. Recent R&D activities in Japan for developing high performance catalysts, for elucidating the reaction mechanism and also for operating a bench scale plant have been reviewed in this paper.

Catalytic methanol decomposition at low temperatures over palladium supported on metal oxides

Abstract: Palladium catalysts supported on metal oxides have been prepared by a coprecipitation method for the selective decomposition of methanol to CO and H 2 . The catalysts whose supports are ZrO 2 , Pr 2 O 3 , and CeO 2 are significantly active at 200–300°C. Turnover frequency determined from the activity of the catalysts containing 15 wt% of Pd at 200°C, increased with an increase in the binding energy of Pd 3d 5/2 for the catalysts, indicating that a positively charged Pd species, most likely Pd + , is preferable for the low-temperature decomposition of methanol. The coprecipitation method is advantageous in the preparation of catalysts containing a large amount of Pd over an impregnation method because smaller Pd particles interacting strongly with the support can be produced by the former technique.

Development of underwater microrobot using ICPF actuator

Abstract: It is our purpose to develop an underwater microrobot that has the characteristics of flexibility, driven by a low voltage, good response and safety in body. In this paper, we propose a new prototype model of an underwater microrobot utilizing ionic conducting polymer film (ICPF) actuator as the servo actuator. The fish-like propulsion using ICPF actuator as a propulsion tail fin for a microrobot swimming structure in water or aqueous medium is developed. The overall size of the underwater microrobot prototype shaped as a boat with a pair of fins is 40 mm in length, 10 mm in width and 2 mm in thickness. The characteristic of the underwater microrobot is measured by changing the frequency of input voltage from 0.1 Hz to 5 Hz. The experimental results indicate that the swimming speed of the proposed underwater microrobot can be controlled by changing the frequency of input voltage.

Structure and Growth of Hexyl Azobenzene Thiol SAMs on Au(111)

Abstract: The structure and growth of functionalized thiol self-assembled monolayers (SAMs) on Au(111) derived from a new compound, 12-(4-((4-hexylphenyl)azo)phenoxy)dodecane-1-thiol (“hexyl azobenzene thiol”), were examined by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), dynamic contact angles, Fourier transform infrared-reflection absorption spectroscopy (FTIR-RAS), and reflection UV−vis absorption spectroscopy. The hexyl azobenzene thiol SAM showed adsorption kinetics comparable to that of alkanethiols. At the initial stage of SAM growth, formation of nanosize domains resulting from the rearrangement of molecules on the surface was confirmed in a similar manner as for alkanethiol SAMs with long alkyl chains. The hexyl azobenzene thiol SAM exhibited a unique molecular ordering due to the intermolecular interaction between tail groups. Molecular resolution AFM images revealed an expanded lattice (nearest neighbor spacings, a = 5.3 ± 0.1 A, b = 5.6 ± 0.1 A; angle between the two axes, φ = ...

Oxygen Reduction Characteristics of Heat‐Treated Catalysts Based on Cobalt‐Porphyrin Ion Complexes

Abstract: Oxygen reduction characteristics of graphite electrodes modified with aggregated cobalt-porphyrins heat-treated at various temperatures and then impregnated in Nafion polymer were investigated systematically. The aggregated cobalt-porphyrin compound was adsorbed on graphite powder and then heat-treated at various temperatures ranging from 200 through 1200 °C. The catalysts were evaluated for electroreduction performances of oxygen on modified electrodes in sulfuric acid solutions. The electrocatalytic performances of catalysts as measured in rotating ring-disk electrodes showed that the most effective catalytic activity for oxygen reduction was attained for the aggregated cobalt-porphyrin compounds on graphite powder heat-treated at temperatures between 600 and 800 °C. The surface concentration of Co and N as measured by X-ray photoelectron spectroscopy increased as the heat-treatment temperature was increased up to 800 °C. The electrochemical performance of pyrolyzed cobalt-porphyrin catalysts changed in parallel with the surface concentration of Co and N. In the temperature range 600-800 °C, it appeared that the increased catalytic activity originated from the well-dispersed Co-N 4 moiety or from fragments of the original molecules still retaining the cobalt bound to nitrogen atoms. In the higher temperature region, Co-N 4 bonds were no longer detected, and the presence of cobalt in the metallic states (β-Co) in the catalysts was confirmed by X-ray diffraction analysis. From the results of the stability tests, the pyrolyzed cobalt porphyrin electrode systems were found to be more stable than the nonheat-treated catalysts.

Reduction of nitrogen monoxide with propene over Au/Al2O3 mixed mechanically with Mn2O3

Abstract: The reduction of NO with propene in the presence of excess oxygen and moisture over gold supported on Al2O3 is appreciably enhanced by the addition of Mn2O3 through mechanical mixing. The conversion of NO to N2 is markedly improved at temperatures below 573 K, above which it reaches 98% without appreciable decrease with an increase in temperature. The conversion of NO increases with an increase in O2 concentration up to 5 vol%, and thereafter it levels off. The role of Mn2O3 is proven to enhance NO2 formation by the reaction of NO with oxygen.

Optical transitions and frequency upconversion emission of Er3+ ions in Ga2S3–GeS2–La2S3 glasses

Abstract: Spectroscopic properties of Er3+ in Ga2S3–GeS2–La2S3 glasses are investigated on the basis of the spontaneous emission probabilities calculated by the use of the Judd–Ofelt theory and lifetime data Frequency upconversion spectra are also measured with excitation at 800 and 980 nm The spontaneous emission probabilities are much larger than those of the other glass systems such as oxides and fluorides This is mainly attributed to the large refractive indices of the sulfide glasses The quantum efficiencies of 4I11/2 and 4F9/2 levels are comparable or larger than the typical values of Er3+ in a fluoride glass This is a consequence of the large spontaneous emission probabilities and low phonon energies of the sulfide glasses However, the quantum efficiency of the 4S3/2 level is less than one-half of the value in the fluoride glass The nonradiative transition probability of the 4S3/2 level is much larger than the value which is evaluated from the multiphonon relaxation theory This suggests the presence

A novel fiber-optic gas-sensing configuration using extremely curved optical fibers and an attempt for optical humidity detection

Abstract: A novel configuration for optochemical sensors is proposed using a single optical fiber which is extremely curved at an angle of 180° and turned back. Although the curvature of optical fiber caused some loss in the transmission of the incident light, this loss was not very large. To examine the utility of a sensor head using the curved fiber, all or part of the curved region was coated with a Rhodamine B/hydroxypropyl cellulose humidity sensing film instead of the normal cladding. When the curved fiber was used instead of a straight fiber, the modulation of the incident light by the sensing film was dramatically enhanced, and the change with humidity in the transmission of the incident light through the sensor became much larger. The light signal of the humidity sensor using the curved fiber exhibited a short response time, a high reproducibility, and a smooth dependence on humidity with little hysteresis effect in a wide humidity range.

Design and accuracy evaluation of high-speed and high precision parallel mechanism

Abstract: We have developed a precise and high-speed arm applied to assembly processes in electrical product and machine industries. The arm is designed based on the requirement from Japanese major industries. The paper addresses the background of the development, the required specification for the robot arm, and the brief introduction of the prototype arm and evaluations of accuracy. We test the repeatability of parallel mechanism. Then we calibrate the kinematic model of parallel mechanism to improve its absolute accuracy using laser tracking coordinate measuring system.

Characterization and Expression of a New Class of Zinc Finger Protein that Binds to Silencer Region of Ascorbate Oxidase Gene

Abstract: A unique A/T-rich sequence (5'-AAAAAGTAAAAA-GTAAAAAAGTAAAAAG-3), referred to as the AGTA repeat, is found in the silencer region of the pumpkin ascorbate oxidase gene. A cDNA for protein (AOBP) that binds to the AGTA repeat was isolated from pumpkin by the southwestern method. The AOBP protein has a new class of zinc/DNA-binding domain named Dof/MOA domain that is highly conserved in many plant proteins and is significantly related to those of steroid hormone receptors and GATA1. Gel retardation analysis indicated that AOBP bound to the AGTA repeat through the Dof/MOA domain. Metal chelators, 1,10-phenanthroline and EDTA, specifically inhibited the DNA binding of AOBP, indicating that metal coordination plays an important role in DNA binding of AOBP. Thus, the Dof/MOA domain acts as a zinc/DNA-binding domain in AOBP. Gel retardation analysis with mutated oligonucleotides suggested that the Dof/MOA domain recognized the AGTA core sequence. AOBP mRNA was expressed in mature tissues of pumpkin, but was expressed only in small amounts or was not expressed in growing tissues. Furthermore, the expression was auxin-independent. The expression pattern of AOBP and that of ascorbate oxidase did not show a positive correlation.

Malignant transformation of NIH3T3 cells by overexpression of mot-2 protein

Abstract: The murine mortalin genes, mot-1 and mot-2, are members of the hsp70 family of proteins and differ from each other by only two amino acid residues. Mot-1 is expressed in normal cells and has pancytosolic cellular distribution whereas mot-2 is found in the perinuclear region of immortal cells. We report here that a high level of expression of mot-2 protein resulted in malignant transformation of cells as analysed by anchorage independent growth and nude mice assays. A high level of protein expression is attributed to the 900 bp 3' untranslated region of the cDNA which does not have any transforming activity per se. Mortalin cDNA clones isolated from human transformed cells were also found to have transforming activity in similar assays and a high level of expression was apparent in some of the human immortalized cells that showed non-pancytosolic mortalin immunofluorescence. Taken together, the data suggest that nonpancytosolic mortalin may have a role in tumorigenesis.

Restoration of superconductivity in high parallel magnetic fields in layered superconductors

Abstract: k c2sT d within the Ginzburg-Landau-Abrikosov-Gor'kov theory and the Lawrence-Doniach model to the case of strong magnetic fields. From this equation, it follows that orbital effects of an electron motion along an open Fermi surface in a magnetic field start to restore superconductivity at magnetic fields higher than the quasiclassical upper critical field and result in the appearance of a reentrant phase with TcsH d. T c s 0 d . A stability of the reentrant phase against fluctuations is discussed. (S0031-9007(98)05633-6)

Self-interference of long-period fibre grating and its application as temperature sensor

Abstract: The authors describe self-interference fringes created in a single long-period fibre grating (LPG) formed in a double-cladding fibre, one end of which is coated with a metal film. The temperature-induced fringe-shift in the reflection spectrum of the proposed LPG device was measured to be 0.055 nm//spl deg/C with 0.9/spl deg/C RMS deviation. Applications of such devices as filters and fine temperature sensors are expected.

Effect on bending behavior of counter cation species in perfluorinated sulfonate membrane–platinum composite

Abstract: The perfluorinated sulfonate membrane (Nafion ®117)–platinum composites having H+, mono- and bivalent metal ions as counter cations in the membranes were prepared and the bending behaviors of the composites actuated by the step voltage were investigated in deionized water. The bending behaviors of all composites have the same tendency as the composites to bend quickly to the anode side just after applying the step voltage and gradually to bend back to the cathode side in spite of keeping on the application. However, they show differences in the bending rate and the maximum displacement to the anode side just after applying the step voltage, which are influenced by counter cation species in the membrane. In particular, the composite having Li+ has the largest maximum displacement (about 1.1 mm) to the anode side. The relationship between the maximum displacements of the composites and water states in the membranes were studied. The maximum displacements of the composites depend on the water content in the membranes. In both series of the composites having mono- and bivalent metal ions, the maximum displacements increase with increasing water content, except the composites having Rb+ and Sr2+ which belong to fifth period in the periodic table. In spite of the result that the water content in the membrane having H+, which is about 20wt%, is nearly equal to that in the membrane having Naa, the maximum displacement of the composite having H+ is only about one-third as large as that of the composite having Na+. The water structures in the membranes were investigated by using differential scanning calorimetry (DSC). The DSC endothermograms obtained indicate that the freezing water in the membrane having H+ has a much stronger interaction with sulfonate groups and counter cations than that in the membrane having Na+. It is concluded that the content and structure of the freezing water in the membrane have a profound effect on the bending behavior of the composite. © 1998 John Wiley & Sons, Ltd.

Two-Parameter Stochastic Resonance in a Model of the Photosensitive Belousov-Zhabotinsky Reaction in a Flow System

Abstract: Stochastic resonance (SR) is shown in a two-parameter system, a model of the photosensitive Belousov−Zhabotinsky reaction in a flow system. Light flux and a flow rate are control parameters in a newly developed Oregonator-type model, and the oscillatory behavior of the system is the dynamical observable. Modulation of an excitable focal steady-state close to a Hopf bifurcation by a periodic signal in one parameter and noise in the other parameter is found to give rise to SR. The scenario and novel aspects of SR in this system are discussed.