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Showing papers by "National Institute of Advanced Industrial Science and Technology published in 1994"


Proceedings ArticleDOI
08 May 1994
TL;DR: The design of a machine which is composed of homogeneous mechanical units, and the control software of the unit which realizes "self-assembly," one of the basic functions of this machine is developed.
Abstract: The design of a machine which is composed of homogeneous mechanical units is described. We show the design of both hardware and control software of the unit. Each unit can connect with other units and change the connection by itself. In spite of its simple mechanism, a set of these units realizes various mechanical functions. We developed the control software of the unit which realizes "self-assembly," one of the basic functions of this machine. A set of these units can form a given shape of the whole system by themselves. The units exchange information about local geometric relation by communication, and cooperate to form the whole shape through a diffusion-like process. There is no upper level controller to supervise these units, and the software of each unit is completely the same. Three actual units have been built to test the basic movements, and the function of self-assembly has been verified by computer simulation. >

416 citations


Journal ArticleDOI
TL;DR: In this paper, a sample of atomic force microscope (AFM) is vertically vibrated at ultrasonic frequencies much higher than the cantilever resonance, the tip cannot vibrate but it is cyclically indented into the sample.
Abstract: We present a novel method for nanometer resolution subsurface imaging. When a sample of atomic force microscope (AFM) is vertically vibrated at ultrasonic frequencies much higher than the cantilever resonance, the tip cannot vibrate but it is cyclically indented into the sample. By modulating the amplitude of ultrasonic vibration, subsurface features are imaged from the cantilever deflection vibration at the modulation frequency. By adding low‐frequency lateral vibration to the ultrasonic vibration, subsurface features with different shear rigidity are imaged from the torsional vibration of cantilever. Thus controlling the direction of vibration forces, we can discriminate subsurface features of different elastic properties.

317 citations


Journal ArticleDOI
07 Apr 1994-Nature
TL;DR: The results suggest that the region at the 50K/20K junction, likely to be part of the myosin head that interacts directly with actin10,13,14, is important in determining the enzymatic activity of myOSin.
Abstract: MYOSINS are a functionally divergent group of mechanochemical enzymes involved in various motile activities in cells1. Despite a high degree of conservation in the amino-acid sequence of the 130K motor domain2,3 (head region) of the molecule, there are large differences in the enzymatic and motile activities (Tables 1 and 2) of myosins from diverse species and cell types. However, the degree of conservation is not uniform throughout the head sequence4; therefore, one reasonable hypothesis is that the functional differences between myosins derive from the poorly conserved areas. The most prominent divergent region occurs at the 50K/20K junction, a region of the molecule sensitive to proteolytic digestion5 and a binding site for actin6–12. We have now constructed chimaeras of this region of myosin by substituting the 9-amino-acid Dictyostelium junction region with those from myosins from other species and find that the actin-activated ATPase correlates well with the activity of the myosin from which the junction region was derived. Our results suggest that this region, likely to be part of the myosin head that interacts directly with actin10,13,14, is important in determining the enzymatic activity of myosin.

206 citations


Journal ArticleDOI
TL;DR: In this article, the effect of dry operating conditions on the oxidation of CO over Co3O4 and Au/Co3O 4 has been studied under dry conditions (with pretreatment and reaction gases dried at −76°C using molecular sieve traps) and at temperatures as low as −54°C.
Abstract: The effect of dry operating conditions upon the oxidation of CO over Co3O4 and Au/Co3O4 has been studied. Under dry conditions (with pretreatment and reaction gases dried at −76°C using molecular sieve traps) oxidation of CO over Co3O4 can be observed at temperatures as low as −54°C. However, without sufficient drying Co3O4 rapidly deactivates. On the other hand, the Au/Co3O4 catalyst is resistant to the presence of moisture even at low temperatures. For both the Co3O4 and Au/Co3O4 catalytic systems, strong and periodic oscillations in percentage conversion and catalyst bed temperature have been observed.

156 citations



Journal ArticleDOI
TL;DR: In this paper, the authors used high-resolution transmission electron microscopy (HRTEM) images of a bend of a planar defect and various kinds of atomic steps, whose ledges are parallel to the [1&1bar;0] direction.
Abstract: Detailed structural data of the {′113} interstitial defect or the rod-like defect in Si and Ge have been given based on firm experimental evidence by high-resolution transmission electron microscopy (HRTEM). We have found line interstitial defect structures, in which a few chains of additional (interstitial) atoms in the 〈110〉 direction are inserted in a perfect crystal without dangling bonds in the {′110} cross-section. We have also found various kinds of atomic steps, whose ledges are parallel to the [1&1bar;0] direction, in the extremely extended {′113} planar defect. The HRTEM images of a bend of a {′113} planar defect have been also presented. The interstitial defect structures mentioned above have been determined by HRTEM with image simulation. Based on the experimental evidence, we have shown that the observed structures such as the extremely extended part on {′113}, the bend, the steps and the disturbed structure in which the hexagonal structure with stacking faults exists have been consi...

103 citations


Journal ArticleDOI
TL;DR: In this paper, X-ray diffractometry and dielectric measurements of BaTiO3 particles were used to investigate the coexistence of tetragonal and cubic phases at room temperature.
Abstract: The crystallographic structure of BaTiO3 particles prepared by conventional solid-state reaction has been investigated by X-ray diffractometry and dielectric measurements. The systematic analysis of the diffraction pattern has clearly shown the coexistence of tetragonal and cubic phases at room temperature. The relative amount of cubic phase increases and the dielectric constant decreases with decreasing particle size. These experimental results are consistent with the model that the cubic phase is located at the surface of BaTiO3 grains. The thickness of the surface layer is estimated to be approximately 5 nm, irrespective of the grain size.

92 citations


Journal ArticleDOI
TL;DR: In this article, an FTIR and quadrupole mass study of CO adsorption and oxidation with 16O2 and 18O2 on Au/ZnO catalysts is presented.
Abstract: An FTIR and quadrupole mass study of CO adsorption and oxidation with16O2 and18O2 on Au/ZnO catalysts is presented. The experimental results indicate that: (i) CO is activated by gold in two molecular forms, a linear carbonyl species bonded at terrace Au sites and a carbonyl species bonded to Au peripheral sites; (ii) a band related to CO adsorbed on Au oxidized sites and a scrambling reaction between CO and18O2 indicate that oxygen is also activated on gold sites. The oxygen adsorbed on gold is probably strongly basic, as is the oxygen adsorbed on silver and on copper, and it can easily oxidize CO to CO2.

79 citations


Journal ArticleDOI
TL;DR: It is demonstrated that parallel fibers can mediate Purkinje cell excitation effectively and over considerable distances in a well-organized spatio-temporal manner, thus supporting the classical view of the physiological role assigned to the parallel fibers.
Abstract: We investigated the synaptic transmission in the parallel fiber-Purkinje cell system at high spatio-temporal resolution by using voltage-sensitive dyes and an imaging system. In rat cerebellar slices, cut in the frontal plane or in a plane of the cerebellar surface, local electrical stimulation induced volleys of action potentials in the parallel fibers; subsequent postsynaptic responses from Purkinje cells were observed along the volleys' entire trajectories. Furthermore, the formation of an ordered spatial gradient in parallel fiber conduction velocity across the depth of the molecular layer during postnatal development was observed. In preparations of adult, but not of immature rats, the conduction velocity of parallel fibers in the deep molecular layer was faster than in its more superficial regions. Our observations demonstrate that parallel fibers can mediate Purkinje cell excitation effectively and over considerable distances in a well-organized spatio-temporal manner, thus supporting the classical view of the physiological role assigned to the parallel fibers.

77 citations


Journal ArticleDOI
TL;DR: In this article, a self-supporting micro-top-seeding mechanism for the growth of 2212 whiskers is proposed, where the bottom part of the whisker is formed by a thin layer of the Bi-Sr-Ca-Al-O complex oxide.

63 citations



Journal ArticleDOI
TL;DR: In this paper, a new high-temperature and nontoxic superconductor Ag1-x Cux Ba2Can -1Cun O2n +3-δ with T c>117 K was discovered.
Abstract: A new high-temperature and nontoxic superconductor Ag1-x Cux Ba2Can -1Cun O2n +3-δ family with T c>117 K was discovered. These materials are prepared by the high-pressure technique. A superconductor sample with the highest T c contains mainly a Ag1-x Cux Ba2Ca3Cu4O11-δ (x=0.75) phase. The phase has a body-centered tetragonal structure with lattice constants of a=7.7270 A and c=36.222 A. The disordering of Ag sites leads to the space group of P4/mmm and the lattice constants of a=3.8635 A and c=18.111 A. The T c value of the Ag1-x Cux Ba2Ca3Cu4O11-δ phase is 117.1 K. The relationship between the lattice constant c and the number of CuO2 layers n is c/2=5.3+3.2n ( A). The small CuO2-block spacing (8.5 A) of this family suggests a lower anisotropy and higher J c than Hg- and Tl-based superconductor families.

Journal ArticleDOI
TL;DR: The drug, adsorbed onto the hydroxyapatite nano-crystals, inhibited cancer cell growth and was investigated using cancer cells.
Abstract: The application of hydroxyapatite-sol as a drug carrier is being developed. Hydroxyapatite-sol which is a suspension consisting of hydroxyapatite nano-crystals, was synthesized using an ultrasonic homogenizer. The size of the crystals was 40 x 15 x 10 mm3 on average and their specific surface area was 100 m2/g. An amount of a glycoside antibiotics adsorbed onto hydroxyapatite nano-crystals was measured. The drug adsorbed 0.2 mg per 1 mg of hydroxyapatite. The affect of the drug adsorbed onto the hydroxyapatite was investigated using cancer cells. The drug, adsorbed onto the hydroxyapatite nano-crystals, inhibited cancer cell growth.

Journal ArticleDOI
TL;DR: In this paper, the authors have succeeded in preparing c-axis oriented high-Jc YBa2Cu3Oy films on MgO(100) substrate by the liquid phase epitaxy (LPE) technique.
Abstract: We have succeeded in preparing c‐axis oriented high‐Jc YBa2Cu3Oy films on MgO(100) substrate by the liquid phase epitaxy (LPE) technique. The growth rate was typically about 2 μm/min, which was 10–102 times larger than that by ordinary vapor growth techniques. The film thickness ranged 10–50 μm by choosing the dipping time. The Tc of the best film exceeded 88 K after oxygen annealing, and the transport Jc was 1.1×105 A/cm2 at 77 K and 0 T. In‐field Jc’s at 77 K and 1.5 T were 2.8×104 A/cm2 and 2.0×104 A/cm2 for the B⊥ab plane and B∥ab plane, respectively. In addition, the peak effect of Jc was observed at several tesla for B∥ab plane geometry. Based on the microstructure observed by high resolution transmission electron microscopy, the relevant peak effect is considered to be caused by stacking faults which act as a field induced pinning center.

Journal ArticleDOI
TL;DR: In this article, perchloroethylene (PER) and trichloroethylenes (TCE) were studied by using a photochemical reaction chamber, in order to clarify their degradation products, particularly carbon tetrachloride (CCl4) in connection with stratospheric ozone depletion by chlorine.

Journal ArticleDOI
TL;DR: In this paper, the shape-selective catalysis of biphenyl with propylene was studied over a cerium exchanged sodium mordenite (Ce/NaM25) and a H-mordenitic (HM25) with the same SiO2/Al2O3 ratio of 25.5%.
Abstract: Liquid phase isopropylation of biphenyl with propylene was studied over a cerium exchanged sodium mordenite (Ce/NaM25) and a H-mordenite (HM25) with the same SiO2/Al2O3 ratio of 25. Shape-selective catalysis occurred to give 4,4′-diisopropylbiphenyl (4,4′-DIPS) in high selectivity over Ce/NaM25 under any propylene pressures. HM25 gave 4,4′-DIPS shape-selectively under high propylene pressures. However, the reaction was severely deactivated at a conversion of ca. 60% under such a low pressure as 0.8 kg/cm2 because of coke formation in the pore. The yields of 4-isopropylbiphenyl (4-IPBP) and 4,4′-DIPB decreased with the increase of those of 3-IPBP and 3,4′-DIPB because of non-selective alkylation and isomerization at external acid sites that are alive in spite of severe deactivation. No significant isomerization of 4,4′-DIPB over Ce/NaM25 was observed even at low propylene pressure. In the case of HM25, the isomerization of 4,4′-DIPB to 3,4′-DIPB occurred significantly under low propylene pressures, while it decreased under high pressure. These differences are ascribed to the differences of nature of acid sites between Ce/NaM25 and HM25 zeolites.

Journal ArticleDOI
TL;DR: In this article, the authors used NiCl2-H2O/PPh3 in the presence of inorganic base for the 4-bromo-4-hydroxyphenyl (4-BH)cinnamate and ethyl acrylate.
Abstract: The vinylation of 4-bromo-4′-hydroxybiphenyl and ethyl acrylate was studied using the catalyst NiCl2-H2O/PPh3 in the presence of inorganic base. Ethyl 4-(4′-hydroxyphenyl)cinnamate was formed as vinylation product with a selectivity as high as 98%. The effect of solvent, ligand and base for some halides was examined to show the applicability of the catalyst system.

Journal ArticleDOI
TL;DR: In this article, the shape-selectivity and coke deposition in the alkylation of biphenyl over H-mordenite (HM) were examined for the catalyst after the reaction.
Abstract: To understand the relationships between shape-selectivity and coke deposition in the alkylation of biphenyl over H-mordenite (HM), thermogravimetric analyses were examined for the catalyst after the reaction. The coke deposition during the catalysis was very severe over HM with low SiO/Al2O3 ratio, however, dealumination enhanced the decrease of coke deposition. Over highly dealuminated HM, volatile organic compounds, mainly biphenyl derivatives, were observed in addition to carbonaceous deposits. The deposits are produced from biphenyl derivatives on acid sites in the HM pore, and the ease of their formation is governed by acid site density and acid strength. The decrease of carbonaceous deposits and the increase of encapsulated biphenyl derivatives are related with the increase of both selectivity and yield of 4,4′-diisopropylbiphenyl (4,4′-DIPB). The increase of reaction temperature up to 250°C enhanced the catalysis over highly dealuminated HM, however, further increase of the temperature resulted in extensive decrease of the selectivity of 4,4′-DIPB. Coke deposition also increased with the temperature although its level was low. The composition of 4,4′-DIPB in encapsulated DIPB isomers remained as high as 80% in spite of a change of the distribution of bulk products.


Book ChapterDOI
TL;DR: In this article, a large amount of cerium impregnation was used to improve the performance of H-Mordenite (HM) catalysts for the isopropylation of naphthalene.
Abstract: H-Mordenite (HM) catalysts impregnated with cerium exhibited high activity and selectivity of 2,6-diisopropylnaphthalene (2,6-DIPN) for the isopropylation of naphthalene with propylene. Cerium modification with such a large amount as 30-50 wt% improved the catalyst performance for every HM catalyst with SiO 2 /Al 2 O 3 ratio between 10 and 220. The highest selectivity of 2,6-DIPN was achieved up to 70% over a highly dealuminated HM catalyst with 30 wt% of cerium. The effective pore dimension of HM catalyst is not reduced by the modification. The improvement of the catalyst performance is ascribed to the selective deactivation of acid sites on the external surface by cerium impregnation.

Journal ArticleDOI
TL;DR: In this article, it was shown that ferromagnetic NaV 6 O 11 (T c = 64.2 K) undergoes two-step second-order structural phase transitions upon cooling: hexagonal (P 6 3 / mmc ) → hexagonal(P 63 mc ) → orthorhombic (Cmc 2 1 ).

Journal ArticleDOI
TL;DR: A series of copolyesteramides based on adipic acid/1,6-hexane diamine/ϵ-caprolactone and Nylon 6,6 salt were synthesized in this paper.
Abstract: A series of copolyesteramides based on adipic acid/1,6-hexane diamine/ϵ-caprolactone and Nylon 6,6 salt/ϵ-caprolactone were synthesized Their molecular weights, determined by gel permeation chromatography and NMR spectroscopy, were found to lie within the range from 1000 up to 7000 Their thermal properties (glass transitions, melting points and heats of melting, and decomposition temperatures) were recorded with diferential scanning calorimetry and thermogravimetry, respectively, and correlated to the comonomer feed composition The FT-IR and NMR spectra were also recorded in order to confirm the composition of the copolyesteramides and to compare them with that of the comonomer feed The biodegradability of the synthesized copolymers was tested by enzymatic hydrolysis Eine Reihe von Copolyesteramiden mit Molekulargewichten zwischen 1000 und 7000 (GPC, NMR) wurden aus Adipinsaure/1,6-Hexandiamin/ϵ-Caprolacton bzw Nylon 6,6-Salz/ϵ-Caprolacton hergestellt Die thermischen Eigenschaften der synthetisierten Polymeren (Glasubergangs-, Schmelz-, und Zersetzungstemperaturen, Schmelzenthalpien) wurden durch DSC- und TGA-Messungen bestimmt und in Bezug auf das Comonomerverhaltnis in der Ausgangsmischung diskutiert Die Ubereinstimmung der Copolymerzusammensetzung mit dem Ausgangscomonomerverhaltnis wurde mit FT-IR- und NMR-Spektroskopie untersucht Die Bioabbaubarkeit der Copolyesteramide wurde durch enzymatische Hydrolyse gepruft

Journal ArticleDOI
01 Oct 1994-Polymer
TL;DR: In this article, statistical copolyamides produced by the simultaneous reaction of the salt of adipic acid and bis(p-aminocyclohexyl)methane and several α-amino acids were characterized by elemental analyses, density and viscosity measurements and Fourier transform infra-red spectroscopy.

Journal ArticleDOI
TL;DR: The cyclotron effective mass ratio of the carriers on the three-dimensional Fermi surface is estimated to be small, 0.05(±0.02) and 0.014(± 0.002) for the magnetic fields perpendicular and parallel to the two-dimensional plane, respectively.

Journal ArticleDOI
TL;DR: In this article, the de Haas-van Alphen oscillations in an organic superconductor were analyzed and the cyclotron masses were estimated to be 2.0 m e and 3.6 m e for slow and fast oscillations, respectively.
Abstract: Analysis of the temperature and field dependence of the de Haas-van Alphen oscillations in an organic superconductor θ-(BEDT-TTF) 2 I 3 is presented. The cyclotron masses are estimated to be 2.0 m e and 3.6 m e for slow and fast oscillations, respectively. The indication of magnetic breakdown effect is discussed in terms of the geometry of the Fermi surface. The result is compared with those of the infrared reflectance spectra and the empirical tight-binding band calculations.

Journal ArticleDOI
TL;DR: The reproducibility of peak areas in this micellar electrokinetic chromatography analysis was as good as that of high‐performance liquid chromatography (HPLC) analysis with the same derivatization method.
Abstract: The analysis of lower aliphatic aldehydes in water following derivatization to 2,4-dinitrophenylhydrazones, was investigated by micellar electrokinetic chromatography (MEKC). The effects of the buffer pH and acetonitrile addition on the separation were investigated. Under optimized conditions the 2,4-dinitrophenylhydrazine (DNPH) reagent was completely separated from four DNPH derivatized aldehydes with high separation efficiency. DNPH-formaldehyde and DNPH-acetaldehyde were also completely separated from one another. Their relative standard deviation of migration times and peak areas were within 1.0% and 3.3%, respectively. The reproducibility of peak areas in this MEKC analysis was as good as that of high-performance liquid chromatography (HPLC) analysis with the same derivatization method. The recovery values from tap and river water were in the range of 97-102%. The detection limits of formaldehyde and acetaldehyde were 0.05 mg/L and 0.08 mg/L respectively.

Journal ArticleDOI
TL;DR: Analysis by RT-PCR suggests that the spontaneously immortalized stage II fibroblasts have enhanced synthesis and secretion of VEGF as compared to their mortal parent cells.

Journal ArticleDOI
TL;DR: In this paper, a 2D mesophase in Langmuir monolayers of 4-octyl-4-4'-(3-carboxytrimethyleneoxy) azobenzene was found.
Abstract: Depolarized Brewster-angle microscopy revealed a novel two-dimensional (2D) mesophase in Langmuir monolayers of 4-octyl-4'-(3-carboxytrimethyleneoxy) azobenzene, characterized by ubiquitous schlieren textures resulting from the long-range order of in-plane molecular orientations. The lack of half-integral strength disclinations and the presence of a regular array of π-walls, across which the in-plane orientation changes by 180 degrees, indicate the vectorial nature of the underlying order parameter. The monolayer can, therefore, be viewed as a single layer of a bulk smectic C phase or as a 2D polar nematic phase, except for the obvious absence of mirror symmetry with respect to the layer plane. In contrast to the experience with bulk liquid crystalline phases, higher-order point disclinations were often found stable in the monolayer.


Journal ArticleDOI
TL;DR: In this paper, the effect of doping on the growth and superconducting properties of whiskers in the Bi-Sr-Ca-Cu-X-O system (where X = Na, B, Ga, and Pb, respectively) was reported.
Abstract: The effect of the doping on the growth and superconducting properties of whiskers in the Bi–Sr–Ca–Cu–X–O system (where X = Na, B, Ga, and Pb, respectively), prepared by heating a glassy melt-quenched plate in flowing oxygen, is reported. The thermal behavior of the glassy samples (studied by DTA, XRD, and SEM techniques) was found to be dependent on the dopant as well as on its concentration. The Bi 2 Sr 2 CaCu 2 O x (2212 phase) whiskers were grown only from the Ga-doped system annealed at 855 °C. The dependence of the mechanism of the whiskers' growth on the dopant is also discussed.