Showing papers by "National Institute of Advanced Industrial Science and Technology published in 1999"

Functional identification and reconstitution of an odorant receptor in single olfactory neurons

Abstract: The olfactory system is remarkable in its capacity to discriminate a wide range of odorants through a series of transduction events initiated in olfactory receptor neurons. Each olfactory neuron is expected to express only a single odorant receptor gene that belongs to the G protein coupled receptor family. The ligand–receptor interaction, however, has not been clearly characterized. This study demonstrates the functional identification of olfactory receptor(s) for specific odorant(s) from single olfactory neurons by a combination of Ca2+-imaging and reverse transcription–coupled PCR analysis. First, a candidate odorant receptor was cloned from a single tissue-printed olfactory neuron that displayed odorant-induced Ca2+ increase. Next, recombinant adenovirus-mediated expression of the isolated receptor gene was established in the olfactory epithelium by using green fluorescent protein as a marker. The infected neurons elicited external Ca2+ entry when exposed to the odorant that originally was used to identify the receptor gene. Experiments performed to determine ligand specificity revealed that the odorant receptor recognized specific structural motifs within odorant molecules. The odorant receptor-mediated signal transduction appears to be reconstituted by this two-step approach: the receptor screening for given odorant(s) from single neurons and the functional expression of the receptor via recombinant adenovirus. The present approach should enable us to examine not only ligand specificity of an odorant receptor but also receptor specificity and diversity for a particular odorant of interest.

Ski is a component of the histone deacetylase complex required for transcriptional repression by Mad and thyroid hormone receptor

Abstract: The N-CoR/SMRT complex containing mSin3 and histone deacetylase (HDAC) mediates transcriptional repression by nuclear hormone receptors and Mad. The proteins encoded by the ski proto-oncogene family directly bind to N-CoR/SMRT and mSin3A, and forms a complex with HDAC. c-Ski and its related gene product Sno are required for transcriptional repression by Mad and thyroid hormone receptor (TRb). The oncogenic form, v-Ski, which lacks the mSin3A-binding domain, acts in a dominant-negative fashion, and abrogates transcriptional repression by Mad and TRb .I nski-deficient mouse embryos, the ornithine decarboxylase gene, whose expression is normally repressed by Mad‐Max, is expressed ectopically. These results show that Ski is a component of the HDAC complex and that Ski is required for the transcriptional repression mediated by this complex. The involvement of c-Ski in the HDAC complex indicates that the function of the HDAC complex is important for oncogenesis.

JNAS: Japanese speech corpus for large vocabulary continuous speech recognition research

Abstract: In this paper we present the first public Japanese speech corpus for large vocabulary continuous speech recognition (LVCSR) technology, which we have titled JNAS (Japanese Newspaper Article Sentences). We designed it to be comparable to the corpora used in the American and European LVCSR projects. The corpus contains speech recordings (60 h) and their orthographic transcriptions for 306 speakers (153 males and 153 females) reading excerpts from the newspaper's articles and phonetically balanced (PB) sentences. This corpus contains utterances of about 45, 000 sentences as a whole with each speaker reading about 150 sentences. JNAS is being distributed on 16 CD-ROMs.

Dependence of fringe spacing on the grating separation in a long-period fiber grating pair.

Abstract: The spectral spacing of the interference fringes formed by a pair of long-period fiber gratings was investigated. The variation of the fringe spacing was measured while the separation between the gratings was changed from 22 to 500 mm. When the grating separation was much longer than the length of the individual grating, the inverse of the fringe spacing became linearly proportional to the grating separation and to the differential effective group index of the fiber. In the third stop band of the grating pair, made along a dispersion-shifted fiber centered at 1.55 µm, the differential effective group index was calculated to be ∼6.4 × 10-3, which is approximately twice the differential effective index of the fiber. The discrepancy between the two indices was observed to decrease with the band order, a phenomenon that is explained by the first-order dispersion of the fiber. The measured interference fringes were not regularly spaced in the frequency domain, but regular spacing is required in wavelength-division multiplexing communication systems. Analysis of the second-order dispersion of the fiber and the grating-induced nonlinear phase shift within grating regions as the factors that induce chirping on the fringe spacing is presented.

Molecular processes of adsorption and desorption of alkanethiol monolayers on Au(111)

Abstract: The adsorption and desorption of n-alkanethiol monolayers on Au(111) have been studied under ultrahigh-vacuum condition by the use of scanning tunneling microscopy (STM), thermal desorption spectroscopy (TDS), and Auger electron spectroscopy (AES). Molecularly resolved STM observations for the alkanethiol monolayers have revealed that at least four different phases evolve during growth, which results in a multistep growth of the monolayer. The desorption species drastically changes at a critical coverage, which is accompanied by a structure change from a low-density flat-lying phase to a denser standing-up phase: While the latter phase bimolecularly desorbs as disulfides, the former phase unimolecularly desorbs as thiolate radicals. The coverage-dependent change of the desorption mode is explained in terms of the difference in the molecule-substrate bonding.

Directed Evolution of Thermostable Kanamycin-Resistance Gene: A Convenient Selection Marker for Thermus thermophilus.

Abstract: The whole-genome sequencing of an extreme thermophile, Thermus thermophilus, is now in progress. Like other genome projects, major concern is shifting from the sequence itself to post-sequencing research such as functional or structural genomics. Under such circumstances, the demand for convenient genetic-engineering tools is increasing. In this study we have increased the thermostability of a kanamycin-resistance gene product using strategies based on directed evolution in T. thermophilus to the upper limit of its growth temperature. The most thermostable mutant has 19 amino-acid substitutions, whereby the thermostability is increased by 20 degrees C, but the enzymatic activity is not significantly changed. Most of the mutated residues are located on the surface of the protein molecule, and, interestingly, five of the 19 substitutions are those to proline residues. The evolved kanamycin-resistance gene products could be used as selection markers at the optimum growth temperature of T. thermophilus. The development of such a convenient genetic-engineering tool would facilitate post-sequencing research on T. thermophilus.

Self-assembly and self-repair method for a distributed mechanical system

Abstract: We propose a self-assembly and self-repair method for a homogeneous distributed mechanical system. We focus on a category of distributed systems composed of numbers of identical units which can dynamically change connections among themselves. Each unit has an onboard microprocessor, and local communication between neighboring units is possible. We discuss a distributed method for a group of such units to metamorphose from an arbitrary configuration into a desired configuration through cooperation by the units. This process, called self-assembly, is realized by identical software on each unit with local inter-unit communication. An extension of self-assembly, self-repair, is also examined. In this process, an occasional cut-off of an arbitrary part of the system is assumed. When some part of the system detects damage, the whole system degenerates and reconstructs itself. Computer simulations show the feasibility of self-assembly and self-repair.

Nitric Oxide Reduction with Hydrogen, Carbon Monoxide, and Hydrocarbons over Gold Catalysts

Abstract: The reactivity of nitric oxide with reducing gases, using supported gold catalysts is reviewed and assessed in comparison with the use of other precious metal catalysts. Applications for this technology in the purification of exhaust gases are envisaged.

CO2 reforming of CH4 over Ni/perovskite catalysts prepared by solid phase crystallization method

Abstract: Ni-supported catalysts on perovskite-type oxides have been prepared by “solid phase crystallization” (spc) method and tested for CO2 reforming of CH4 into synthesis gas at 850°C. The Ni catalysts were obtained in situ during the reaction from the oxides as the precursors in which nickel species were homogeneously incorporated in the perovskite structure. Ni/Ca0.8Sr0.2TiO3 and Ni/BaTiO3 catalysts showed high activity as well as high sustainability among the catalysts tested. The high activity may be due to highly dispersed and stable Ni metal particles (diameter

Photocatalytic decomposition of benzene over TiO2 in a humidified airstream

Abstract: Photocatalytic decomposition of benzene over TiO2 in the gas phase at room temperature was studied with a fixed-bed flow reactor. In a humidified airstream ([H2O]=2.2%), benzene was efficiently decomposed to CO2 and CO with the selectivities of 93 and 7%, respectively. The selectivities were almost independent of the benzene conversion, indicating that CO is not the intermediate of CO2 in the reaction. The selectivity of CO was in the range of 7–10% with varying concentration of O2, H2O, and benzene. The formation of phenol and brownish carbonaceous matter attributable to polymeric products was observed on the catalyst surface. In the absence of O2, benzene oxidation did not proceed at all, showing that O2 is essential for the reaction. The presence of H2O not only suppressed the formation of the carbon deposits on the catalyst surface, but also accelerated the decomposition of them to CO2 and CO. Diffuse reflectance IR study showed that the presence of H2O regenerated the surface hydroxyl groups of TiO2 which were consumed in the photoreaction. With increase in the benzene concentration, the benzene conversion was decreased and the amount of carbon deposits on the catalyst surface was increased.

Effects of basis set and electron correlation on the calculated interaction energies of hydrogen bonding complexes: MP2/cc-pV5Z calculations of H2O–MeOH,H2O–Me2O,H2O–H2CO, MeOH–MeOH, and HCOOH–HCOOH complexes

Abstract: The MP2 intermolecular interaction energies of the title complexes were calculated with the Dunning’s correlation consistent basis sets (cc-pVXZ, X=D, T, Q, and 5) and the interaction energies at the basis set limit were estimated. The second-order Mo/ller–Plesset (MP2) interaction energies greatly depend on the basis sets used, while the Hartree–Fock (HF) energies do not. Small basis sets considerably underestimate the attractive interaction. The coupled cluster single double triple [CCSD(T)] interaction energies are close to the MP2 ones. The expected CCSD(T) interaction energies of the H2O–MeOH, H2O–Me2O, H2O–H2CO, MeOH–MeOH, and HCOOH–HCOOH complexes at the basis set limit are −4.90, −5.51, −5.17, −5.45, and −13.93 kcal/mol, respectively, while the HF/cc-pV5Z energies are −3.15, −2.58, −3.60, −2.69, and −11.29 kcal/mol, respectively. The HF calculations greatly underestimate the attractive energies and fail to predict the order of the bonding energies in these complexes. These results show that a large basis set and the consideration of an appropriate electron correlation correction are essential to study interactions of hydrogen bonding complexes by ab initio molecular orbital calculation.

Improved segmental isotope labeling of proteins and application to a larger protein

Abstract: A new isotope labeling technique for peptide segments in a protein sample was recently established using the protein splicing element intein [Yamazaki et al. (1998) J. Am. Chem. Soc., 120, 5591–5592]. This method makes it possible to observe signals of a selected amino (N-) or carboxyl (C-) terminal region along a peptide chain. However, there is a problem with the yield of the segmentally labeled protein. In this paper, we report an increase in the yield of the protein that enables the production of sufficient amounts of segmentally 13C/15N-labeled protein samples. This was achieved by improvement of the expression level of the N-terminal fragment in cells and the efficiency of refolding into the active splicing conformation. The N-terminal fragment was expressed as a fused protein with the cellulose binding domain at its N-terminus, which was expressed as an insoluble peptide in cells and the expression level was increased. Incubation with 2.5 M urea and 50% glycerol increased the efficiency of the refolding greatly, thereby raising the final yields of the ligated proteins. The feasibility of application of the method to a high-molecular-weight protein was demonstrated by the results for a maltose binding protein consisting of 370 amino acids. All four examined joints in the maltose binding protein were successfully ligated to produce segmentally labeled protein samples.

Seasonal and inter-annual variation of CO2 flux between a temperate forest and the atmosphere in Japan

Abstract: The objective of this research is to elucidate the seasonal and inter-annual variations of CO 2 exchanges between the atmosphere and a temperate deciduous forest in Japan and to elucidate their relation to meteorological conditions. The uptake rates of CO 2 from October 1993 to December 1996 were estimated from field measurements of CO 2 concentrations and meteorological conditions using a tower. Net of uptake rate of CO 2 was positive (uptake by forest ecosystems) from June to September and negative (release to the air) from October to April. Averages of integrated uptake rates of CO 2 were 840, − 450 and 390 gCO 2 /m 2 /year (2.3, − 1.2 and 1.1 tC/ha/year) for daytime, night and whole day (net), but they had notable inter-annual variation due to the differences of averaged insolation and temperature each summer of 1994 to 1996. The errors of CO 2 flux due to topographical conditions were investigated through comparison with heat budgets. CO 2 uptake rate estimated by tower measurement might be underestimation of 40%, therefore, above net-uptake value, 1.1 tC/ha/year became 1.8. This value of uptake rate was smaller than the results obtained in other temperate deciduous forests. The causes of this are partially in the difference of the height of the site and the short active period of the present forest. According to the CO 2 flux measurements in several forests including the present one, the forest ecosystems could be a large sink of CO 2 , however, more data of the CO 2 flux is needed at the various forests and latitudes to reduce the uncertainty of estimation of CO 2 uptake on a global scale. DOI: 10.1034/j.1600-0889.1999.00020.x

Torsional potential of biphenyl : ab initio calculations with the dunning correlation consisted basis sets

Abstract: The internal rotational barrier heights of biphenyl were calculated with the Dunning correlation consisted basis sets (up to cc-pVQZ, 960 basis functions) and the electron correlation correction by the second order Mo/ller-Plesset method (MP2). Although previous Hartree–Fock (HF) and MP2 calculations showed that the internal rotational barrier height at 0° (ΔE0) was substantially larger than that at 90° (ΔE90), our MP2/cc-pVQZ//MP2/6-31G* calculations showed that ΔE0 (2.28 kcal/mol) was close to ΔE90 (2.13 kcal/mol), which agreed with the estimation from experimental measurements. The calculations of benzene dimers suggested that the dispersion interaction increased the relative stability of the coplanar conformer. The basis sets employed in the previous calculations were not large enough to evaluate the attractive dispersion interaction. The underestimation of the stabilization of the coplanar conformer by the dispersion interaction would be one of the reasons for the overestimation of ΔE0 in the previous calculations.

Negative activation energies in CO oxidation over an icosahedral Au/Mg(OH)2 catalyst

Abstract: In the course of our studies on CO oxidation over Au/Mg(OH)2 we have discovered a catalyst which exhibits an apparent negative activation energy when studied under ultra‐dry conditions (80 ppb moisture content). A review of current literature suggests that the oxidation of CO may occur by a reaction between CO and OH radicals and not by oxygen as previously thought. Substantial differences in catalytic behaviour between low and high temperature suggest that the reaction is complex and that more than one reaction pathway is present.

Generation and complete electric-field characterization of intense ultrashort tunable far-infrared laser pulses

Abstract: Intense rapidly tunable picosecond laser pulses have been generated in the far infrared from 30 to 250 \ensuremath{\mu}m, a range not well covered by other sources. The transform-limited, diffraction-limited pulses have energies of up to 17 \ensuremath{\mu}J, peak powers of more than 1 MW, a length of only 18 optical periods, and focused intensities of 0.1 $\mathrm{GW}/{\mathrm{cm}}^{2}$. Measurements of both the optical field amplitude and the phase have been performed at 150 \ensuremath{\mu}m with a rapid-scanning cross-correlation technique probing the field-induced birefringence in ZnTe with a 10-fs Ti:sapphire laser. The far-infrared laser opens up the exciting possibility of performing nonlinear experiments in a relatively unexplored spectral range.

Dielectric properties of spark-plasma-sintered BaTiO3

Abstract: Spark-plasma-sintering (SPS) has been applied to BaTiO3 to prepare dense ceramics consisting of submicrometre-sized powder. Relatively dense (typically 97% of the theoretical X-ray density) pellets with an average grain size remaining similar to that of the starting powder, approximately 0.6 μm, were obtained by the SPS process. Fixed frequency (1 kHz) measurements show the room temperature permittivity of SPS ceramics to be relatively high, approximately 3500, and at least double the value of conventionally sintered ceramics, approximately 1500. Alternating current (a.c.) impedance spectroscopy measurements show that SPS is an effective process to reduce the influence of intergranular (grain boundary) effects on the permittivity and direct current (d.c.) resistance characteristics of BaTiO3 ceramics substantially.

Preparation of LiCoO2 and LiCo1–xFexO2 using hydrothermal reactions

Abstract: Iron doped/undoped LiCoO 2 powders could be obtained from hydrothermal reactions of either Fe 3+ or Co 3+ containing co-precipitates or a CoCl 2 -NaOH-NaClO 3 (oxidant) mixture with an excess amount of LiOH·H 2 O at 220 °C for 8-48 h. The LiFe x Co 1–x O 2 solid solution maintained a layered rock-salt structure until x=0.25. 57 Fe Mossbauer and Co K-edge XANES spectra and magnetic susceptibility data reveal that iron and cobalt in the solid solution are in high-spin Fe 3+ (S=5/2) and low-spin Co 3+ (S=0) configurations.

Effects of the surface Cu2−xSe phase on the growth and properties of CuInSe2 films

Abstract: Drastic changes in average molecularities (m=Cu/In) from m≫1 to m=0.92–0.93 and in hole concentrations from p≫1019 cm−3 to as low as p=7.5×1016 cm−3 have been observed in molecular beam epitaxy grown CuInSe2 after selective etching of the Cu–Se phase by a KCN aqueous solution; high hole concentrations and Cu-excess compositions of the as-grown films were attributed to the Cu–Se phase. On the other hand, well-defined photoluminescence emissions were found characteristic of intrinsic CuInSe2. The presence of the Cu–Se phase made possible the growth of high-quality CuInSe2 epitaxial films at a temperature well below the melting point of any Cu–Se compound. Surface topology measurements showed that the surface of the as-grown films was not fully covered by Cu–Se grains, leaving holes with depths of 200–300 nm after KCN etching. The enhanced two-dimensional growth and the reduced defect concentration imply that a very thin Cu-excess surface layer controls the growth of CuInSe2 when grown under Cu-excess condit...

Development of small-sized 3 DOF finger module in micro hand for micro manipulation

Abstract: A dexterous micro manipulation system was developed for applications such as assembling micro machines, manipulating cells, and micro surgery. We have proposed a concept of a two-fingered microhand, and designed and built a prototype. We succeeded in performing basic micro manipulations, including the grasp, release, and rotation of a microscopic object. The two-fingered micro hand prototype should be more miniaturized for higher accuracy and combination in small chamber of SEM. In this paper, we will propose a small-sized 3-DOF finger module with a parallel mechanism. An optimized link mechanism for miniaturization is used to the finger module. A photo fabrication system is used to fabrication of the finger module. Basic experiment shows excellent micro capability.